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Full report - ECE - Cornell University

1. The largest error I made with trying to use the CAN bus on this project was underestimating the difficulty in enabling basic use of the technology Specifically I was trying to simultaneously develop new software while also trying to develop the hardware that the software was running on Developing both at once made it incredibly difficult to track down errors I did not have any CAN bus communications working which was due primarily to my inability to either guarantee that board design was correct and that I had a software issue or to verify the software was working and that I maybe have had the wrong pin mappings on one of the chips on the board Although the design did not work the schematics of the board can be found in Figure C5 Despite these shortcomings using a CAN bus would have still had its benefits The final software version for the CAMS has a complicated software communication architecture which must include acknowledgement timeouts and retries in software which could have been handled by proper configuration of the CAN controller However I did not have the proper development tools expertise and most importantly time to enable the use of CAN technology for the CAMS so a simple UART bus scheme was implemented The selection rationale and implementation details for the UART bus can be found in the Design section of this report Mechanical Designs Considered The first mechanical design option was a conveyor belt based system
2. CAN version 2A and 2B The main difference between these two versions of the protocol is that version A only allows for 11 bit identifiers whereas version B allows for 29 bit identifiers There are some other changes in packet structure between these two protocols but they exist only to enable the additional identifier length Aside from these differences the protocols operate in the same way The CAN protocol is broken down into the physical layer the transfer layer and the application layer The physical layer implements differential pair bit signaling where a 0 is indicated by a high voltage on the bus called a dominant bit and a 1 is indicated by a low voltage recessive bit The wire harnessing in a CAN bus requires a characteristic impedance of 120 Ohms and requires an additional terminating resistor of 120 Ohms at either end of the bus Data frames are specified at the transfer layer and consist of a start of frame bit an identifier a set of control bits including payload size a variable size payload the CRC and delimiter an ACK bit and delimiter and an end of frame field Bus arbitration error detection and acknowledgement are all handled at this layer Lastly the programmer is able to interface with the CAN based system at the application layer Transmission and reception of messages at the application level are handled through a set of message objects that contain all the necessary information about the content and status of a m
3. a Introduction CREE M Alternative Designs Considered cree erre eere eere e eee ees eso se esssesesossseseseeessseeessseessses O COMMUBICALONS S CIC TUITE td ic teo iiem IAU edili 6 Cnstom Static Network occa e tee Ro an eua eere gatus 6 CAN Bus Commumications S tructure 2 oet eee aaa Loro te ee andl 7 Mechanical Desisas Considereda alate cia 8 Compressed AMzer kreret rai rt nie 9 IBI purse Doro HT Electrical BITS 11 Prototype Circuit Borra ele el 11 CARE BOS REPE 11 Solenoid Valve Driving Circuit ainia init 12 Mechanical Desi A 13 Software Desidia inni ra a a v Mun p E M EE 15 Br ede eie e e e doen 15 Main Board SON Witt dii paria tini ns ata ini 16 VIII AS RR E LEO 16 User AICTE siena aaa 17 COMMIS rail Oma ORDRE EE 17 Mod le Board TOR E e cause 19 Initialization and UART ISR lui 19 Connessi T ia ataca 19 Ultrasonic Sensor and Valve Control e e e ien Ele eee 20 Results iocdecscadescccccudsccceadesccsosoucecsesdesecseswideccsedesseassedceususdescdsocndscusesdevacsnecscesctsdebecsocuevecstedeidssoscsces 2D Sensor Experiments oen viste sued cass ER UR cheated DRE Min rm weed abet aee Bi UR deu Poeta uiro IRE UR ERI es 22 UART Bus Willie 22 Valve Calibration Tests 55 fee ices etae ete tei ase e eee ERE 23 Reducing Electronics COSE 0 ee pre re eR asa Pu e URN 26 Mechanical Design Updates esto epe qr eoa
4. 1015 995 18 1000 1044 1024 18 5 1040 1073 1053 19 1070 1102 1082 19 5 1100 1131 1111 20 1140 1160 1140 20 5 1170 1189 1169 21 1200 1218 1198 21 5 1200 1247 1197 DI 1220 1276 1226 22 5 1250 1305 1255 23 1280 1334 1284 23 5 1310 1363 1313 24 1330 1392 1342 Echo Pulse Width vs Distance 1600 1400 1200 1000 800 600 400 200 0 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 e Measured Pulse Width Datasheet Model Experimental Model Figure El Graph of Ultrasonic Sensor Test Table E2 Error of Ultrasonic Sensor Models Page 49 Measured Sensor Distance cm Datasheet Model Error Experimental Model Error 4 19 59 1 03 4 5 17 57 0 45 5 16 94 0 81 5 5 14 75 0 36 6 13 73 0 65 6 5 14 24 2 12 7 12 78 1 67 7 5 6 6296 1 7296 8 7 41 2 18 8 5 6 25 1 94 9 6 10 2 03 9 5 3 57 0 19 10 1 40 2 10 10 5 0 83 2 48 11 0 31 2 83 11 5 3 57 0 47 12 0 58 2 31 12 5 4 17 1 29 13 3 57 0 82 13 5 3 57 0 93 14 3 57 1 02 14 5 3 57 1 11 15 3 57 1 19 15 5 3 57 1 27 16 4 27 2 02 16 5 4 02 1 85 17 3 79 1 68 17 5 3 57 1 53 18 4 40 2 40 18 5 3 17 1 25 19 2 99 1 12 19 5 2 82 1 00 20 1 75 0 00 20 5 1 62 0 09 21 1 50 0 17 21 5 3 92 0 67 22 4 59 0 08 22 5 4 40 0 00 23 4 22 0 08 23 5 4 05 0 15
5. 19 by the start time and the global time then the function returns false regardless of the components of the handshake that have been completed Regardless of if the cocktail order was a success once the orderDrink function is exited the main board prompts the user to enter another menu item number to order and repeats the process An example of a full drink ordering process starting from system initialization to successful dispensing of multiple ingredients can be found in Figure A1 in Appendix A Module Board Software Initialization and UART ISR Initialization of the module board proceeds in a similar manner to the main board initialization First the pins on port D are configured to allow proper transmission and reception on UARTI Next the address of this module is copied in to a variable Unfortunately there is currently no easy way to assign module numbers without slightly changing the code recompiling and reprogramming for each module On a production design the initialization code would include some way to indicate the module number such as using pull up and pull down resistors on a port or using a keypad After the module number is recorded then the UART is initialized by calling uart init The UART is configured for 9600 baud rate and the receive ISR is enabled The receive ISR will execute every time a byte is successfully received on UARTI The ISR copies the contents of the receive buffer into a variable used by the main so
6. 4 5cm on the third trial is clearly an outlier so it is removed to improve accuracy of the trend line but included in the graph in the same color as the rest of the data series The graph of all three runs with the trend line from the third data set is found in Figure E2 The trend line was useful for characterization of the valve and very useful for determining a first pass estimation for valve duration for 22mL of liquid The equation for the trend line is Volume Dispensed in 100 ms mL 0 3767 Distance to Sensor cm 26 72 cm Dividing this by the total time 100 ms gives an average flow rate which can be used to estimate time to dispense 22mL The flow rate is not constant over the duration because of the switching time of the valve but the average is a good first order approximation without analyzing the mechanical properties of the solenoid Linearity of the data provided an easy first pass estimation for determining how long to hold the valve open The first estimation is given in Table E4 which lists a distance valve duration in ms and measured volume On the estimation experiments the estimated values are rounded to the nearest millisecond so only a millisecond timer was used to coordinate the valve The maximum possible error on this scheme is one half of a millisecond The internal counter that sets the millisecond time base is cleared right before the valve timing starts to ensure that that the number of milliseconds the va
7. 54 Single Row Male Pin 0 00356 pin 42 pins 0 14952 Header Dual Row Male Pin 0 0375 row 3 rows 0 1125 Header Microcontroller 7 75 1 7 75 2 1mm Power Jack 0 93 1 0 93 SPDT Switch 0 91 1 0 91 White Breadboard 5 95 1 5 95 Custom PCB 33 1 33 Total Cost 57 92 Table D3 Module Board Components Page 44 Component Name Unit Cost Quantity Total Price Diode 0 11 2 0 22 10kQ Resistor 0 08 1 0 08 1kQ Resistor 0 08 i 0 16 3300 Resistor 0 08 2 0 16 100Q Resistor 0 08 1 0 08 luF Capacitor 0 20 2 0 40 100nF Capacitor 0 10 9 0 90 22pF Capacitor 0 16 2 0 32 16MHz Crystal 0 66 1 0 66 Green LED 0 06 1 0 06 DIP Socket 0 51 1 0 51 A 4 50 1 4 50 Converter 5V Regulator 0 95 1 0 95 Opto isolator 0 43 1 0 43 USB B Socket 0 54 1 0 54 i Male 0 00356 pin 42 pins 0 01 Dual Row Marois 0 3 rows 0 11 Header Microcontroller 7 75 1 7 75 2 1mm Power Jack 0 93 1 0 93 SPDT Switch 0 91 1 0 91 White Breadboard 5 95 1 5 95 Custom PCB 33 1 33 00 1MQ Resistor 0 08 1 0 08 10KQ Resistor 0 08 1 0 08 3300 Resistor 0 08 2 0 16 NFET 1 34 1 1 34 Ultrasonic Sensor 3 13 1 2 89 Total Electrical Cost 63 42 Table D4 Mechanical Components Page 45 Component Name M
8. 96 22 9 94 20 100 23 5 9 5 95 21 98 22 10 96 20 101 23 10 5 97 20 102 23 5 11 97 20 103 22 5 11 5 98 20 104 24 12 99 20 104 23 12 5 100 22 100 21 5 13 101 20 5 105 22 13 5 102 22 5 100 21 5 14 103 19 5 109 22 14 5 103 21 106 21 5 15 104 21 107 21 15 5 105 21 108 22 16 106 20 112 21 16 5 107 21 110 21 17 108 20 114 22 Page 53 Appendix G Ultrasonic Sensor Datasheet The datasheet for the ultrasonic sensor is not hosted on the manufacturer s site but is hosted instead at micropik com Ultrasonic Ranging Module HC SR04 However the manufacturer s product page has several other resources listed including a User s Manual and Software Library for integration with an Arduino HC SR04 Ultrasonic Sensor 2011 ELEC Erea ks COHEN ech Support services elecfreaks com Ultrasonic Ranging Module HC SR04 Product features Ultrasonic ranging module HC SR04 provides 2cm 400cm non contact measurement function the ranging accuracy can reach to 3mm The modules includes ultrasonic transmitters receiver and control circuit The basic principle of work 1 Using IO trigger for at least 10us high level signal 2 The Module automatically sends eight 40 kHz and detect whether there is a pulse signal back 3 IF the signal back through high level time of high output IO duration is the time from sending ultrasonic to returning Test distance high level timexvelocity of sound 340M S 2 Wire con
9. Appendix D Component Costs This Appendix contains a reference for the part numbers and costs used to estimate a price for each CAMS module Please note that the values listed in these tables are for reference only the actual price and availability of electrical and mechanical components may vary significantly The electrical component costs here are all taken from digikey com Digi Key Electronics 2014 unless otherwise listed The mechanical component details are all taken from usplastics com United States Plastics Corporation 2014 Price comparisons for the existing systems are taken from their respective product websites Party Robotics 2014 BoozeBots 2014 Monsieur 2014 Table DI Electrical Components Component Name Manufacturer Part Number Unit Cost Diode Comchip Technology 1N4001 G 0 11 NFET Infineon Technologies BUZ73 H3046 1 34 IMQ Resistor Stackpole Electronics CF14JT1M00 0 08 100kO Resistor Stackpole Electronics CF14JT100K 0 08 10kQ Resistor Stackpole Electronics CF14JT10K0 0 08 3300 Resistor Stackpole Electronics CF14JT330R 0 08 1000 Resistor Stackpole Electronics CF14JT100R 0 08 luF Capacitor Kemet C1206CIO4K3RACTU 0 20 100nF Capacitor Kemet C1206C104K3RACTU 0 10 10nF Capacitor Kemet C1206C103JARACTU 0 12 4 7nF Capacitor Kemet C1206C472K5RACTU 0 14 22pF Capacitor Kemet C1206C220K5GACTU 0 16 16MHz Cry
10. Unfortunately it is impossible to know exactly how the cost will change until other container designs are investigated and evaluated for cost and applicability to the system The largest mechanical component that needs a proper redesign in the structure used to hold the valve ingredient container and module board The existing design uses wooden and Styrofoam components that were available in the laboratory during design Not only are those designs not reproducible because the wooden structure is a custom structure left over from old lab equipment but it is not desirable to reproduce those designs because they are not well suited for the CAMS A proper design would have a more stable way to hold the ingredient bottle in place and a sturdier method of holding the valve based on the exact weight and dimensions of the valve Because the ultimate goal of the CAMS is to be a consumer product it is important for the structural design to be able to handle getting knocked in to or otherwise battered by an ordinary user Several structural designs must be prototyped and tested to determine cost and user friendliness of each design to read the optimal design User Interface Updates Another aspect of the CAMS design that was not fully completed was the user interface for ordering cocktails As discussed the existing design has the framework for ordering any cocktail off of the menu but it has to be done from a plain serial terminal The purpose of the
11. a scheme is used to directly map liquid height in the module to a duration of time to hold the valve open This duration is calibrated to dispensing one part 22mL of volume of the ingredient The valve durations were determined through a set of experiments Due to limited accuracy of laboratory equipment the mapping from liquid height to valve duration only has a granularity of one half centimeter Details on how the measurement and mapping are calculated can be found in the Ultrasonic Sensor and Valve Duration section of this report The precision of the valve duration is discussed in the Results section of this design report The structure of the module is a large rectangular wooden box which stands upright on its smallest side and the front face is open This box also contains a set of sixteen small wooden guides along the long sides of the box to allow any configuration of shelves to be used The shelves used in the prototype are made 5 Styrofoam which was used due to availability in the laboratory The valve assembly rests on the first shelf which sits on the 1 shelf slot which is located 2 125 above the counter The top shelf is 12 above the bottom shelf and is used to hold the ingredient bottle in place This shelf has a rectangular hole cut out of the middle that is 2 5 across by 4 deep The curve of the ingredient bottle rests in place on top of this shelf while the valve rests slightly above the bottom shelf supported by a tube c
12. basic serial communications was to demonstrate the method that the menu information and selection could be efficiently transmitted to and from the user Now that the basic infrastructure is in place there are several ways to update the user interface without having to redesign way information is encoded The most cost effective way to do this is to use a Bluetooth module and a smartphone app to take drink orders from customers A user would download an application for their smartphone that would perform the same tasks as the current menu and ordering scheme but would not require the orders to be placed one by one at a terminal When the application is first started it attempts to establish communication with the main module Once communication is established the main module would then send the menu over the Bluetooth connection However instead of a user simply choosing a number from a list the application would display just the name and ingredients in a more user friendly way than just plain text It would also be easy to have options to sort and search through drinks in a number of ways such as alphabetically popularity by ingredient list or by alcohol content The Android development environment could be used to quickly write and test such an application The system cost would be increased by the cost of the Bluetooth module used for communication although the serial chip would not be necessary which would counteract some of the cost However
13. because at this time there are only seven 2 bit entries but this can be easily expanded to any integer size to accommodate the size of drinkEntryBits A drinkEntryUnion is embedded in a drinkEntry struct which is the struct used to store cocktail entries in a library There is a string field in a drinkEntry struct that holds the name of the cocktail and a drinkBitUnion The syntax for referencing an individual bit field from the highest level structure is cumbersome as a field within drinkEntryBits within drinkEntryUnion within drinkEntry must be referenced However the algorithmic performance on this data structure is fast The algorithmic performance is discussed in the Main Board Software Initialization section of this report Memory space requirements increase logarithmically instead of linearly because every power of 2 number of bit fields requires one larger size unsigned integer in drinkBitUnion to be able to access all fields at once Using an array of unsigned 8 bit integers instead of bit fields would make each library entry take up a significant amount of space 16 allowable ingredients would only require 4 bytes of drinkEntryBits space but using an array would take up 16 bytes This may not seem significant for small numbers of drinks on the menu but when scaling up to hundreds of drinks the library Page 16 can take up a large portion of available memory Also if a smaller microcontroller is used to save cost see the Reducing El
14. needs to be conducted across all solenoid valves and possibly other types of electrically controlled valves to determine what the cheapest solution is A basic search seems to indicate that valves of a smaller diameter are cheaper which is expected but a full study must be conducted to validate these claims Not only should a trade study be conducted for the plastic bottle connectors but other connection schemes should be investigated to see if there is a more efficient way to connect the bottle to the tubing However as previously discussed the mechanical design of the CAMS was not completed before the submission of this design report A 200z soda bottle was used to hold ingredients because it was readily available but it did not lead to the most robust design The cost of this bottle was not taken into account because it is difficult to estimate the cost although it is expected that the cost of the plastic is low However for a more robust design another container type should be selected This container must be safe to hold alcohols for long periods of time and must allow a rectangular hole in the top to house the ultrasonic sensor It is likely that this container will cost more than the cheap plastic soda bottle but it is also possible that a new container would have an NPT or other standard connection which would allow for the use of a cheap polypropylene or polyethylene connector instead of the expensive brass hose connector Page 28
15. plugged into breadboards and connected directly to the UARTI microcontroller pins In the unlikely event that two microcontrollers are both trying to drive the bus at the same time each transmitter pin has a 1kQ resistor between the pin and the bus so there is ample protection for both the transmitters and the receiver It is also possible that at some points in time no module boards are driving the bus so the receive line going to the main board is weakly pulled to 5V through a 10kQ resistor During development before the resistor was used when there were no modules driving this line any transmissions to the modules on the bus caused reflections on the receive line This was likely due to the undriven receive line coupling to the transmit line which caused anything that was transmitted to be reflected on the receiver Adding this resistor eliminated this problem For further noise prevention the ground lines of each board are connected to avoid an issue with inconsistent grounds Long solid core wires are also not ideal for harnessing the CAMS They are brittle and have poor electrical qualities for long lengths of wire However they were sufficient for the CAMS prototype A low baud rate was used on the UART bus in case that the long wires had significant delay The main board s transmit pin is connected to each of the modules individually and each of the module board s transmitters are all connected to the main board s receiver This is not s
16. simple two layer board based on board dimensions Advanced Circuits 2014 Using the dimensions of the existing prototyping boards purchasing 100 boards would cost 4 02 per board which is a savings of 28 98 or 29 6 over the existing module costs Combined with previously discussed methods of reducing electronics cost on the boards I estimate that each module could be made for 55 35 which is 46 6 cheaper than the prototypes This calculation does not include purchasing all components in bulk or conducting full trade studies to determine the cheapest components that can be used while still maintaining proper operation of the CAMS Mechanical Design Updates Analyzing cost changes to the mechanical design is more complicated From the parts list Table DS it is clear that the best way to reduce mechanical cost is to use a different solenoid valve and to use a different connector to go from the plastic bottle to the tubing The cost of the tubing and connectors can be reduced by purchasing components in bulk but the cost of the valve and the hose connector dominates the mechanical cost It may be possible to find a cheaper solenoid valve of the same size but careful attention must be paid so that the new valve is also beverage safe Similarly another connector may be found to connect the ingredient bottle to the tubing but it also must be of a safe material However to properly optimize costs of the mechanical subsystem a proper trade study
17. the number of valid modules present and updates the beverageModules array indexed by ingredient number that indicates which module each ingredient is located in After each ingredient is entered the CAMS increases the module number on the prompt populating the internal module list one by one If ingredient number 99 is entered that indicates that all modules have been listed and to move on to the next step in the process If 100 is entered that indicates the user is requesting a software reset Software reset occurs by turning on the watchdog timer to the fastest setting and waiting in a while 1 loop until the timer expires This forces a software reset and the microcontroller with clear the watchdog timer when it reinitializes After the stock is populated printStock is called to print the results of populateStock in a readable format This serves no functional purpose it is just included for diagnostics After the modules have been configured the CAMS determines given what cocktails it knows how to make which cocktails can be made with the given stock of ingredients This is done through the checkTotalAvailability function which leverages the allBits field in a drinkEntryUnion which is a concatenation of all of the bit fields combined to quickly determines whether or not a cocktail can be made First for each drink in the global library the allBits field is logically ANDed with the allBits field of the module stock that was populat
18. there are two main challenges associated with using a smartphone application The first is coming up with a secure way to run set up and diagnostics on the system The current implementation requires that the bartender populate the modules in stock from the same terminal that a user uses The bartender would either have to still use a serial connection to set up the modules and receive status messages about the system or he would have to be running a different application that had only utilities for populating modules and receiving messages This would require additional software development to write a second application and to allow one application to run set up the system and let other applications to order cocktails regularly To service all beverage requests in parallel the main module would also likely need to implement a queue of cocktails to be ordered and keep track of which devices ordered which beverages When Page 29 a beverage reaches the front of the queue and is prepared a notification would be sent to the appropriate device to let the right user know to come to the bar and pay for their beverage The second challenge associated with using a Bluetooth framework is that a Bluetooth master can only actively communicate with up to 7 slaves There has been some research into constructing ad hoc networks of Bluetooth devices but Bluetooth is not a common means of communication so there are very few resources on how to build an ad hoc netwo
19. was extremely modular The connections coming from the compressed air tank could be resized at will using additional tube splitters and an appropriate structure design would allow each module to be built and installed separately Based on previous designs available through the Cornell ECE 4760 course page the solenoid valve control would use an opto isolator circuit that was controlled by a microcontroller pin and powered from a power supply large enough to quickly switch on and off the valves Land 2013 This seemed like an obvious choice for the mechanical design of the CAMS There were two main issues that arose through development that resulted in only partial adoption of this plan The first is that there was not sufficient development time to fully design and construct the system of valves tubes and splitters that would make up the core of the liquid and compressed air delivery system Additionally the cost of the compressed air tank regulator additional tubing connectors valves and required circuitry would cause the cost of the CAMS to skyrocket Including the cost of the valve for beverage dispensing the mechanical components of Page 10 each additional module would cost 66 98 see Appendix D Component Costs Between this and the total BOM cost for the module boards each module could cost up to 139 50 which is was well above the desired price point of each module Once I resolved not to use compressed air I wanted to determin
20. 1 and the standard deviation was 1 33 The piecewise linear model was easy to program on the microcontroller using a few conditional statements and floating point operations UART Bus Reliability Distance cm The design of the CAMS requires that modules disconnect themselves from transmitting on the bus when not in use According to the ATEMGA1284P datasheet the UART transmitter can be turned on and off at will The datasheet does not specify after how many cycles the Page 23 transmitter is enabled that it is available to send data so the software polls the transmit buffer empty flag UDREI in the UCSRIA register to wait until the transmitter is ready When the bus is weakly pulled to ground through a large resistor the first byte that is sent after a UART transmitter is enabled is always corrupted The root cause of the corrupt byte issue had not been determined but it is expected that when the bus goes from passively being pulled low to being driven high when the UART transmitter turns on then the receiver confuses this transition with a transition associated with a UART byte in a message This issue is resolved by weakly pulling the bus to 5V so that when the transmitter is turned on there are no voltage level transitions Pulling the bus to 5V eliminated all reliability issues all transactions were successful without any retries However the communication stack was able to handle the errors with pulling the bus to ground wit
21. 24 4 66 0 53 Page 50 Table E3 Results of Constant Duration Valve Test Volume Dispensed in 100 ms mL Distance from Sensor to Liquid cm First Run mL Second Run mL Third Run mL 4 23 24 25 4 5 23 18 32 5 23 24 5 5 18 30 6 23 25 6 5 24 q 29 24 7 5 14 23 24 8 23 8 5 30 22 24 9 21 23 9 5 17 23 10 20 23 10 5 21 23 22 11 18 29 23 11 5 25 21 22 12 21 23 12 5 21 15 23 13 14 20 22 13 5 21 28 22 14 20 12 22 14 5 26 23 21 15 19 20 21 15 5 15 28 21 16 19 16 20 16 5 25 22 20 17 19 15 20 Page 51 Volume Dispensed vs Liquid Height 35 32 5 e 30 e 27 5 25 eee 22 5 20 17 5 15 12 5 10 3 3 5 4 4 5 5 5 5 6 6 5 7 7 5 8 85 9 9 5 1010 51111 51212 51313 51414 51515 51616 51717 518 Distance from Sensor to Liquid cm Volume Dispensed mL Figure E2 Volume Dispensed in 100ms vs Distance from Ultrasonic Sensor to Top of Liquid Table E4 Calibration Data for Valve Durations Page 52 Run 1 Run 2 Distance from Valve Duration Volume Valve Duration Volume Sensor to Liquid ms Dispensed mL ms Dispensed mL cm 4 87 20 93 24 5 4 5 88 20 5 92 23 5 89 20 94 24 5 5 89 20 5 93 23 6 90 21 93 23 6 5 9 20 5 95 23 7 9 20 97 23 5 7 5 92 21 95 23 8 93 20 5 97 21 8 5 94 21
22. 39 Serial Communications j ji 1C3 Power Magie de EET 1 lj XTAL a a Bypassing ant owt GND Les CTs a C12 mes mm c8 100nF 100nF 22pF 22pl GND ToonF A E i E adio mx Toonr ToonF Test Points GNb 100nF ee GND 3 gt 1 Ls R4 1k To UART Module Bus MM AMA 1k R8 U3 Solenoid Valve GND ATMEGA1284P PU VALVE_POWER GND ISO 1 Valve Power Ground Separate from MCU Ground Figure C3 Module Board Schematic Figure C4 Constructed Module Board Solenoid Valve and Valve Power Rail Connections Disconnected Page 40 Serial Communications o MCU Bypassing Caps Power Circuit o gt P XTAL2 PGO WR PGI RD PG2 ALE TOSC2 PGS TOSC PGA PAO PF7 ADC7 TD PAL Pre ADOS IDO PAZ PFS ADCS TMS EM C4 PA3 PF4_ ADC4 TCK PAS PF3 _ ADC3 4 7nF 10nF PAG PF2_ ADC2 PAS PFI_ ADC1 PA7 PFO_ ADCO RXDO PDI PEO SCK PB1 TXDO PDO PE1 ART IX MOSI PB2 XCKD AINO _PE2 MISO PES OC3A AINT PES OC2A PB4 OC3B INT4 INTE INT OC1A PB5 OC3C INTS OC1B PB6 T3 OCOA OC1C PE7 ICP3 A8 SCL INTO PCI A9 SDA INT A10 RXD1_ _INT2 A11 TXD1 INT3 A12 ICP1 A13 TXCAN XCK1 A14 RXCAN T1 A15 CLKO T9 XTAL Circuit oo Ma 22pF 22pF AT90CAN128 16AU Gr MCP2551 VSN Figure C5 AT90CAN128 Breakout Board Page 41
23. A the CAMS runs between 1 6A and 2A it can handle a Vas of 60V CAMS runs between 6V and 7V and it can handle up to 38W of power CAMS uses at most 14W This NFET costs 0 78 for individual units a savings of 1 15 and purchasing 100 units costs 0 524 per unit which is a savings of 1 406 per module Combining the savings of the updated solenoid driver with the updated microcontroller can save 7 1526 per board which gives a total module savings of 6 9 Designing the CAMS was done with a prototyping board for the ATMEGA 1284P and used several breadboards and DIP components The prototyping board has some extra hardware on it that is not needed for a production board and combining the DIP components on the breadboard on to the same board as the microcontroller would eliminate the need for the 5 95 breadboard entirely To promote reusability of the prototyping boards the ATMEGA 1284P chips used are DIP components that fit into sockets mounted on the boards This way if a 7 75 chip breaks the chip can be replaced without having to replace the entire 57 92 board However for a production board the 0 51 DIP socket is not needed because the chips are not expected to break Also located on the development board was an FTDI chip and associated components used to communicate with a PC over a serial connection The CAMS prototype uses the Port D UART pins and does not need any PC connection so all of that hardware can be removed All of the se
24. ART bus to all module boards and the appropriate module board responds to the command over the UART bus and utilizes and ultrasonic sensor to determine how long to hold a solenoid valve open for to dispense the correct amount of liquid Most importantly the prototype meets all of its core design premises First the CAMS is less expensive than all existing systems even though the prototype has additional hardware needed for development and debugging A full mechanical design is going to add cost per module but there are many cost optimizations that can be done for the electrical design to drive down the cost per module so that the CAMS is still more cost effective than all other systems Second the CAMS is scalable The current initialization process and the UART bus scheme allow a wide range of modules to be used to prepare many different cocktails Minor software updates will be required to provide an even greater range of ingredients and cocktails but the software infrastructure for these additions already exists The software architecture will not have to be altered to accommodate for additional modules All of the system components function properly together and the prototype design easily allows the expansion from a few modules up to a maximum of 64 The constructed modules cost analysis and system structure clearly demonstrate a strong proof of concept for the Cocktail Automation Management System to be an accurate cheap and scalable bartend
25. Oed eu tap at exl bcn eus 27 User Interface Update Sreser eucons tede en eg aE rR E A OE dua REEE RA 28 CEP ie LEET OI maana LINA E EET AE caia OL Appendix A Software and User Interface eesoosoessessossoesscssossocssossoseocesoesocesossoesosesessosssessesese IZ Appendix B Mechanical Design Appendix C Circuit Board Schematics and Design ssesseesossseescssosesoesoeescesossoesscesossosssessessse 37 Appendix D Component Costs e seessesseesossscesoesosescesoesosesossoesocesossoesoessossoessessoseoeesossosssessossosssesso L Appendix E Experimental Results ouoonoomosnsisssss 7 Appendix G Ultrasonic Sensor Datasheet seesoesoessessossoesscssossocsscssoseoocsoesocesossoesosesessossssssessse DI Page 3 Table of Figures and Tables Table Al List of Ingredient Numbers and Names eese nennen 32 Table A2 List oft Cocktails spirale gy acs tornei e d e a edit uie Ads 32 Figure Al Example Successful Serial Console Output eee 23 Figure A2 Example Successful Ordering Sequence Using a Grounded Bus 34 Figure B1 Front Mechanical View of a CAMS module seen 35 Figure B2 SolidWorks Model of Mechanical Structure esee 36 Figure C1 Main Board Schematic acrilici 38 Figure C2 Constructed Main Board eiie aida is 38 Figure C3 Module Board Schematic oae oret isis Use kr bor
26. Page i COCKTAIL AUTOMATION MANAGEMENT SYSTEM A Design Project Report Presented to the School of Electrical and Computer Engineering of Cornell University In Partial Fulfillment of the Requirements for the Degree of Master of Engineering Electrical and Computer Engineering Submitted by Cameron Glass cig23 MEng Advisor Bruce Robert Land Degree Date August 2014 Page ii Abstract Master of Engineering Program School of Electrical and Computer Engineering Cornell University Design Project Report Project Title Cocktail Automation Management System Author Cameron Glass Abstract The purpose of the Cocktail Automation Management System CAMS is to offer a complete hardware software system that automatically prepares cocktails for patrons at a bar or restaurant This systems consists of a central processing board that handles user requests and coordinates communication among modules which each hold one ingredient The CAMS would complement or replace bartenders for easy to mix beverages which would free up the bartenders for work that could not be automated such as payment collection and more complex cocktails The CAMS delivers beverages by acting in two stages order determination and component delivery First a patron orders a cocktail from a list of available drinks using a serial terminal running on a PC Then for each ingredient in the cocktail the CAMS determines what module the ingredient is located in and wha
27. The modules would be mounted above a conveyor belt and the tubes would go from the modules down to near the Page 9 belt When a cocktail was ordered the bartender would place a glass on the belt and the system would move the glass under the appropriate tube and then dispense the liquid Once the beverage was ready the bartender would grab the cocktail from off the belt Mounting the modules directly above the belt would eliminate the possible need for compressed air and tubing From a patron s perspective it might also be fun to watch the cocktail be made as it travels down the belt However this method is not very suitable for a modular system and it is not expected to have a high throughput of cocktails The conveyor belt system is not very modular because the belt assembly would have to be resized whenever additional modules were added It would be possible to use a larger belt than is necessary to accommodate for a variable number of modules but it would be wasteful to have a conveyor belt that could fit ten modules on it when only four modules are installed Next the conveyor belt would also have to be run very slowly to not spill any liquids One of the goals of the CAMS is to aid bartenders during peak demand and so the system would not be useful if it had to be run slowly to make sure the cocktails would not spill The conveyor belt would require a calibration method to make sure the glass was aligned properly under the tubes Compre
28. ain a destination identifier up to 8 bytes of payload and built in acknowledgements the communications software could be simpler because many basic communications tasks could be handled by the built in CAN controller A considerable amount of development time was put into enabling use of the CAN bus but in the end it proved to not be the best technology for this project Many of the features that initially made CAN attractive made progress slow and halting First enabling the use of a CAN microcontroller required designing a printed circuit board testing it producing a second revision and then further testing before any meaningful communications software development could start The board work provided some exciting work and experience developing a new circuit board but it took development time away from other aspects of the project Next the integrated CAN controller on the board actually made it more difficult to debug issues Because of the way the CAN controller is built in the Atmel architecture attempting to send any message required a complicated set of register commands which made it difficult to identify the faulty step in the process The demonstration code offered by Atmel was very difficult to parse and was also not helpful in trying to develop just a simple board to board communications demonstration Additionally I did not have any access to CAN bus analyzers or logic analyzers which would have made development significantly easier
29. al pair used in USB connections and vice versa A female USB type B connector is connected to the chip and easily connects the UARTO on the microcontroller to a PC Page 12 Given the hardware on the boards PC to microcontroller communication is relatively simple From the microcontroller message transmission the standard fprintf function can be configured to output formatted strings on UARTO When the microcontroller receives a message a flag indicates there is a byte waiting in the receive buffer at which point either an ISR can be entered or the receive buffer can just be read by the main software On the PC side the USB connection is interpreted as a serial communications port COM port and any program that can handle serial I O can bind to this COM port and interact with the microcontroller PuTTY a free Microsoft Windows serial terminal program was used to communicate with the main board A baud rate of 9600 was selected for the PC communications The speed could have been increased but slower baud is more reliable and the channel was not nearly saturated so it was not necessary The UARTI channel on the microcontrollers was used to allow bus based UART communication The most efficient way for the main module to issue commands to anywhere from 1 to 64 modules was to use a bus Because the current CAMS system is a prototype the bus does not have a proper harness structure The bus is implemented by using solid core wires and resistors
30. anufacturer Part Number Unit Cost en 34 Garden Hose to 12 Hose Watts LFA 684 9 995 ar HDPE 7 Male NPT to Hose Barb q iis ea Move Bal United States Plastic Corporation 62017 0 36 Converter Brass Solenoid Valve Geerte 2W 160 15 24 95 Bev A Line Plastic Tubing United States Plastic Corporation 56282 2 62 foot HDPE 2 Male NPT to 2 Hose Barb e Mel SR GA United States Plastic Corporation 62043 0 55 90 elbow HDPE 77 Hose Barb T Connector United States Plastic Corporation 62067 0 55 Pol lene 2 Hose Barb 90 CUPIDO BOs sayy Genova 22520 0 58 elbow Pol lene 1 2 Hose Barb Y ee United States Plastic Corporation 62256 0 91 Splitter Table DS Single Valve Module Mechanical Components Component Name Unit Cost Quantity Total Price Brass 34 Garden Hose to 2 Hose Barb 9 99 1 9 99 HDPE 2 Male NPT to 1 2 Hose Barb Converter 0 36 2 0 72 Brass Solenoid Valve 24 95 1 24 95 Bev A Line Plastic Tubing 2 62 foot 1 5 feet 3 93 Plastic 2 Male NPT to 1 2 Hose Barb 90 elbow 0 58 1 0 58 Total Mechanical Cost 40 17 Table D6 Compressed Air Module Mechanical Components Component Name Unit Cost Quantity Total Price Brass 34 Garden Hose to 2 Hose Barb 9 99 1 9 99 Plastic Y2 Male NPT to 2 Hose Barb Converter 0 36 2 0 72 Brass Solenoid Valve 24 95 2 49 90 Bev A Line Plastic Tubing 2 62 foot 3 feet 7 86 Plastic 2 Male NPT to 1 2 Hose Barb 90 elbow 0 55 2 1 10 Polypropyl
31. as filled to very near each half centimeter marking Normal operation of the CAMS does not result in the liquid levels falling exactly at these intervals In some sections of the ingredient bottle dispensing 22mL drops the liquid height 5cm but in other sections it drops the height by a different amount The ultrasonic sensing software rounds the liquid height to the nearest 5cm so error will be introduced if the actual height is not a multiple of 5cm There was one last issue with the test set up and the success of this prototype of the CAMS The ingredient bottle is too thin for the ultrasonic sensor to measure properly When the top of the liquid is very close to the top of the bottle the ultrasonic measurement is very accurate and allows the valve to be held open for the appropriate number of milliseconds However the sensor effectively saturates at 10cm as it reads all further distances as 10cm To get an accurate distance throughout the entire length of the ingredient bottle a bottle of adequate thickness Page 25 throughout needs to be selected Such a bottle could not be found within the time constraints of this design project but it is a major design concern for the future to ensure accurate operation at all times Page 26 Future Work Reducing Electronics Cost The CAMS prototype is not optimized for cost most components were selected because they were either readily available or because I already have development experien
32. asonic sensor mounted on top of the ingredient bottle The ultrasonic sensor has a four pin interface it has 5V and ground connections a trigger pin and an echo pin To save power the ultrasonic sensor is not constantly sending out ultrasonic pulses and measuring the distance It only performs a measurement when a 10 microsecond pulse is sent to the trigger pin At that point the sensor sends out a series of ultrasonic pulses and performs calculations to get a distance measurement The calculated distance is output from the sensor to the object on the echo pin in the form of a signal pulse ranging from a few hundreds of microseconds to tens of milliseconds The sensor datasheet provides a formula for determining measured distance from the output pulse width but an experiment was run to determine the validity of this model The datasheet for the ultrasonic sensor can be found in Appendix G The experiment the results of which are discussed in the Results section of this design report indicated that the model was not quite correct The data had similar functional form to the model so an experimentally determined model was created to be able to more accurately estimate distance based on the ultrasonic pulse width A lookup table would have been the most accurate way to estimate distance based on pulse width but the experimental setup in the laboratory did not allow for accurately determining a distance for each possible pulse width Across the lengt
33. ates a request it just needs to look up on which of the four ports the desired module is located on and sends a request to one of four ports No board needs to maintain exact location nor does the protocol require a complicated routing method the route is deterministic The second benefit is that the design time of this protocol would be relatively short All the ports are have same physical and electrical specifications regardless of which board or module they are on or if they are an input or an output port Additionally the simple message types and message structure are relatively easy to program on a microcontroller However there are many negative aspects of this design Designing a circuit board takes considerable design time and if there are three different designs needed main interface and module then the time to just have all the necessary boards produced would triple The same board design could be used for all three boards but that would require each board to have five Page 7 ports and make the module and central boards larger than necessary which would make the final design physically bulkier Additionally three different types of board designs would result in three completely different sets of software regardless of the physical board design Lastly and most importantly developing a tree structure of nodes would require significant harnessing and a large number of boards Even producing these boards in bulk would likely n
34. calable because attempting to plug in 64 wires the maximum number of modules into a single microcontroller pin would be physically difficult to implement and it is likely that the pin does not have the driving strength for the fan out of 64 microcontroller pins However not enough hardware was present in the development laboratory to allow for the testing of large scale buses Solenoid Valve Driving Circuit Each module dispensed a single liquid ingredient from a bottle for storage to a cocktail glass or other container for consumption The flow of the ingredient from the bottle to the glass was regulated by a solenoid valve located between the bottle and the tubing that carried the ingredient to the glass This solenoid valve is driven by a small set of circuitry uses a different power source than the regular microcontroller power This separate power source is necessary because the solenoid valve used is a heavy brass solenoid valve that takes a minimum of 6V and 1 6A which is more voltage and current than can be provided by the regulator that powers the microcontroller The microcontroller is able to control the opening and closing of the valve even through turning off and on and opto isolator which in turn allows for either no voltage or 6V to be Page 13 dropped across the valve A schematic of the opto isolator circuit can be found in the bottom of the module board schematic found in Figure C3 of Appendix C An opto isolator works by
35. cated in and what volume of that ingredient is needed A command is issued over a UART bus to each of the relevant modules to dispense the specified ingredient Each dispensing command executes a small handshake between the main board and the module which allows the main board to specify which module it is attempting to send a command to followed by the number of parts of liquid to dispense Specifying a number of parts to dispense allows more complex cocktails of varying volumes to be made The bus does not have any collision management as the communication method is designed to only have one node communicating on the bus at a time Delivery of messages is ensured by a system of acknowledges on each command Modules dispense ingredients to the cocktail being made by opening and closing a solenoid valve connected to beverage grade plastic tubing which transports the liquid into a cocktail glass Each time a module gets a dispensing command it must determine how long to hold the valve open as a function of the current volume of liquid in the bottle and the number of parts of liquid specified by the main board Ingredient bottles have a hole cut out at the top of them which houses an ultrasonic sensor When a reading is initiated by the module board the ultrasonic sensor determines the height of the liquid remaining in the bottle The microcontroller then reads that value and uses it to index a lookup table to determine how long to hold the valve open Th
36. ce with those or similar components As a result there are many cost and complexity optimizations to be made to help further reduce the price Without the PCB and breadboard costs the electrical components for the module cost 24 40 The easiest way to cut costs of circuitry is to shrink the MCU Even within the ATMEGA series there are several other microcontrollers that are cheaper with enough functionality to fulfil the needs of the CAMS The currently used ATMEGA1284P has a base price of 7 75 whereas the ATMEGA324P and ATMEGA48P have base prices of 6 10 and 2 75 respectively Using the ATMEGA48 would save 5 on board costs and would require minimal development cost because the microcontrollers are in the same product family For reference purchasing 100 ATMEGAAS microcontrollers in bulk would cost 2 0034 per unit whereas the same number of ATMEGA1284P would cost 5 73 per unit Switching to the ATMEGA 48 and purchasing in bulk would reduce the cost of each module board by 5 7466 Another way to save on board cost is to update the circuit that drives the solenoid valve Currently the valve is driven by an opto isolator circuit which costs 1 93 in resistors transistors and an IC Switching to a circuit that is based on a single power NFET could reduce the cost of circuitry because it requires fewer components One such example transistor is the Fairchild Semiconductor RFD3055LESM9A NMOSFET This transistor can handle a drain current of 11
37. consists of a central processing board that handles user requests and coordinates communication among modules which each hold one ingredient A module consists of a plastic bottle an ultrasonic sensor a valve a group of tubes and connectors a structure to mount these components and a microcontroller board with associated circuitry to run the module components Some tasks needed to run a bar are difficult to automate so the system is intended to complement or replace bartenders for easy to mix beverages Preparing more advanced cocktails collecting payments swapping out bottles and many other tasks will still have to be carried out by trained bartenders When the CAMS is turned on it prints a list of all the cocktails available to be made given the current modules and then prompts the user to select a cocktail to be made The CAMS delivers beverages by acting in two stages order determination and component delivery First a patron orders a cocktail from a list of available drinks using a serial terminal running on a PC Then for each ingredient in the cocktail the CAMS determines what module the ingredient is located in and what volume of that ingredient is needed A command is issued over a UART bus to each of the relevant modules to dispense the specified ingredient The bus does not have any collision management as the communication method is designed to only have one node communicating on the bus at a time Delivery of messages is ensure
38. d by a system of acknowledges on each command When a module receive a dispense command it dispenses its ingredient into plastic tubing that connects directly to the bottle containing the ingredient and ends in an area located above a cocktail glass Ingredients are dispensed from the bottles using a solenoid valve and the process is controlled by a microcontroller on the module board There are several other beverage automation solutions which are either developed by hobbyists or are attempting to attain commercial production through the online crowdfunding platform Kickstarter Such systems include the Party Robotics Bartendro the Inebriator the BoozeBot and Monsieur These systems also offer complete hardware software solutions but none of these systems are cheap modular or scalable They all require the purchase of a specific sized system and if at a later point more modules are desired for the system an entirely new system must be purchased with no way of using the existing system For example the Monsieur and the nebriator both only allow for a set number of ingredients The BoozeBot and Bartendro both have different models but provide no way of scaling between models to increase system size and functionality a new system must be purchased The CAMS is designed to use as few as one ingredient module and as many as 64 ingredient modules The main controller is separate from the ingredient modules and the ingredient modules only ne
39. e ee ta edd cibo cago 39 Figure C4 Constructed Module Board Solenoid Valve and Valve Power Rail Connections Discomnect d lit ra ER ata in asia bid 39 Figure C5 ATIOCAN128 Breakout Board conii er erede oa 40 Table DI Electrical Components pill 41 Table D2 Main Board Components sims a id donan abans 43 Tabl D3 Module Board Components iaa 44 Table D4 Mechanical Components iicet sieved avons qus aep vues ei E vule dA MEN Veg VOUS adu ad VL INR Seg dee 45 Table DS Single Valve Module Mechanical Components esee 45 Table D6 Compressed Air Module Mechanical Components eere 45 Table D7 Compressed Air System Module Costs eese sienne enne eene 46 Table D8 Single Valve Module Costs ii A lend pied onaes 46 Table D9 Price C Ompablsols oec De o ter ton att nep nita de dne D e af ue 46 Table E1 Results of Ultrasonic Sensor Test rl 47 Figure El Graph of Ultrasonic Sensor Testeado lalla aa 48 Table E2 Error of Ultrasonic Sensor Models doce e E pe Rene 49 Table E3 Results of Constant Duration Valve Test eese 50 Figure E2 Volume Dispensed in 100ms vs Distance from Ultrasonic Sensor to Top of Liquid 51 Table E4 Calibration Data for Valve Durations seen 32 Page 4 Introduction The purpose of the Cocktail Automation Management System CAMS is to offer a complete hardware software system that automatical
40. e how much liquid remained in the tube undispensed after the valve had closed I found out that the brand of plastic tubing I used does not maintain an appreciable amount of undispensed liquid There is liquid in the elbow connector but this is negligible compared to the cost of a compressed air based CAMS The volume in the elbow connector was found to vary by amount of liquid dispensed When IOmL was dispensed then about 4mL of liquid remained in the elbow connector When 20mL was dispensed then only 1 mL of liquid remained in the connector This effect is likely due to the higher volume of liquid providing more weight and force to push all liquid out of the connector It is important to note that this is not a constant loss per dispensing The first time a module is used some of the liquid will remain in the connector After that the trapped liquid will be forced out by the new dispensing of liquid and a few mL will be left behind after that but no net liquid will be lost Also it was found that the geometry of the valve and tubing assembly affected the amount of retained volume Given that volume losses would be negligible the CAMS design does not address this remaining liquid Page 11 Design Electrical Design The most important design principals of the CAMS are high modularity low cost and ease of use The design revolves around a central processing board that handles all user requests and communicates with a up to 64 number of self conta
41. e not implemented Instead a prototype was built using components and materials already available in the laboratory The system design is not complex but it still properly houses the three main components of the mechanical system the container to hold the module ingredient the solenoid valve for dispensing the ingredient and the structure to hold all of the components A picture of a module structure can be found in Figure B1 and a model from the mechanical CAD program Solidworks can be found in Figure B2 The ingredient is contained within a 700mL Poland Spring water bottle These plastic bottles were used because they are easy to obtain they are cheap and the bottle itself is not heavy which helps reduce the load requirements of the mechanical structure Fortunately the threaded cap size of the plastic bottle closely resembles the dimensions of a 3 garden hose so a standard connector can be used The fit between the connector and the bottle is not perfect but it is suitable for a prototype The remainder of the valve plastic bottle and beverage grade plastic tubing are connected together through a set of standard connectors The plastic bottle is connected to a Brass 34 female garden hose to 4 plastic tubing connector called hose barb The tube then extends 2 75 to an HDPE 1 2 hose barb to 1 2 male national pipe thread NPT converter which is screwed into the solenoid valve The other side of the solenoid valve is con
42. e scheme used to connect the microcontroller to the module electronics may also require updates to fit the chosen connector A properly designed CAMS would have a better container system The hole at the top of the plastic bottle is suitable for equalizing the pressure as liquid flows out of the container but it does not ensure that the sensor is pointed directly downwards in the container Tilting the sensor can impact the accuracy of results Lastly the method of refilling an empty module requires that the bottle be pulled out of Page 15 the module and then filled up at the top Pulling out the bottle also requires carefully removing the valve assembly A better CAMS design would not require removing the internal assembly to restock the ingredient These design improvements were not implemented due to development time constraints Given additional time these changes would have been pursued to improve the robustness usability and space usage of the CAMS Software Design All of the CAMS software is written in C developed on Atmel s AVR Studio and run on the ATMEGA1284P microcontrollers either on the main board or on a module board The software that runs on the main and module boards is slightly different The main board software runs the code to initialize the system runs the user interface and coordinates communication on the UART bus to the modules using a protocol that leverages UART capabilities on the microcontrollers The module boa
43. e the ingredient This is achieved by calling the sendCommand function with arguments as the module number as determined through the beverageModules array and the number of parts indicated by the numParts variable The sendCommand function returns either true or false if it returns false then sendCommand prints that the request to a specific module failed which module failed and which ingredient was not present This information is not relevant to the user ordering the drink as they only care that their drink was not prepared However the bartender can see which module wasn t functioning properly and inspect it and by knowing which ingredients weren t dispensed he or she can manually add in the remaining ingredients The sendCommand function calls the function to send the specified data over the bus but also implements retries to allow for noise and disturbance on the bus The bus driving function uartSendB yte is first called to send the specified number of parts to the specified module number If the sending fails it tries twice more before returning false Each time sending the data fails the message No response is printed to the terminal and sending is retried If the data is unsuccessfully sent over the bus three times the sendCommand function returns false If any of the three attempts succeeds then the message transaction complete is printed to the terminal These messages help indicate if there were any failures on the bus befo
44. e ultrasonic sensor and the solenoid valve so that they could be used as accurately as possible during CAMS operation to consistently deliver cocktails to a user in a timely manner There are several shortcomings with the prototype which have been identified throughout this report The most notable is that a proper mechanical structure has not been designed and implemented and the ingredient bottle gets too narrow at points for the ultrasonic sensor to function properly These are not particularly challenging design constraints but due to the limited development time allowed by this project they could not be addressed at this time Aside from the noted shortcomings there are also several ways to improve the existing CAMS design Many of these ways were discussed in this report and these improvements range from an improved user interface to optimizing the bill of materials used to reduce costs without sacrificing functionality All of this being said the CAMS prototype was successful The major design subsystems either function correctly or specific issues have been identified to fix the design The existing system allows for a large range of functionality across many modules A user must program the system to indicate which ingredients are in which modules but different ingredients can be programmed each time at start up and the CAMS will determine which cocktails it can prepare When a user orders a beverage the main board sends a command over the U
45. e ultrasonic sensor reading is necessary because the volume of liquid in a bottle determines the flow rate out of the bottle as described through Bernoulli s Principle of fluid flow There are several other beverage automation solutions either developed by hobbyists or are attempting to attain commercial production through the online crowdfunding platform Kickstarter Such systems include the Party Robotics Bartendro the Inebriator the BoozeBot and Monsieur These systems also offer complete hardware software solutions but none of these systems are cheap modular or scalable They all require the purchase of a specific sized system and if at a later point more modules are desired for the system an entirely new system must be purchased with no way of using the existing system For example the Monsieur and the Page 5 Inebriator both only allow for a certain number of ingredients The BoozeBot and Bartendro both have different models but provide no way of scaling between models to increase system size and functionality a new system has to be purchased The CAMS is designed to use as few as one ingredient module and as many as 64 ingredient modules The main controller is separate from the ingredient modules and the ingredient modules only need connections to power and to the communications bus to add functionality to the system Additionally the expected cost of the CAMS is significantly lower than the existing systems per module Acr
46. ectronics Cost section of this design report then having a smaller memory requirement would make it easier to find a cheaper microcontroller Main Board Software Initialization Initializing the CAMS is done in three steps First low level setup code runs to clear and turn off the watchdog timer configure the on chip UART hardware for eight bit UART at 9600 baud Hardware timer 0 is set up to provide a 1 millisecond time base used in the communication protocol Next the global library of drinks is populated from the file drinkLibrary h by calling populateLibrary Each entry in the library is one cocktail that the CAMS can prepare which is encoded by a drinkEntry struct This library does not represent the cocktails that can be made at that time that cannot be known until the contents of each module is determined in the next step Next the function populateStock is called to allow the user to set up the modules currently in use in the CAMS The user is prompted to indicate what ingredients are located in each module The CAMS sends the prompt What is in slot 0 to the serial terminal and the user enters a number corresponding to an ingredient number and then presses enter This method requires that the user setting up the system knows the mapping from ingredient names to ingredient numbers The table of ingredient numbers and corresponding names can be found in Table A1 Each successful ingredient entry increases a variable indicating
47. ed connections to power and to the communications bus to add functionality to the system Additionally the expected cost of the CAMS is significantly lower than the existing systems per module Across all systems including CAMS the greater number of modules purchased the cheaper the effective module price as cost of the main controller is distributed over many modules The most expensive and least cost effective product is the Monsieur which has a rate of 500 per module and the most cost effective per module is the BoozeBot which costs 62 5 British Pounds or about 108 The CAMS prototype has a per Page liv module cost of 103 35 The cost of the largest BoozeBot system is more than the cost of an equally sized CAMS Lastly the prototype cost of the CAMS was driven up significantly by the debug hardware used and buying each part individually There are several components used for debugging on the module boards that can be removed for production to reduce cost and purchasing components and producing boards in bulk would significantly drive down the cost per module Page 1 Table of Contents Cocktail Automation Management System sccsscccsssscssssscssssccsssssssssscssssscsssssscsssssssssssssssceooel si RRA Executive Summary l Table of COMtemts scc ccccssccecciccsocccceccosdsdessossdccccasdesscsososcoesosdsdocaesedenesoecesdcsoooscoosesdebosascedeoescedetcesessseoeda IL Table so Bione rear
48. ed in the previous step If the result is non zero that means there are some bit fields in the current stock that are non zero that are also non zero in the same place in the library entry This means that there is at least one ingredient in the library entry that the current modules have in stock Next this resulted is XORed with the library entry and checked if the result is zero If only some of the bit fields from the library entry matched the stock that means that there were some ingredients from the library entry that were present in the populated stock If that is true then the XOR will be nonzero because the ingredient fields that were not present in the current stock will be ones while the previous AND with the current stock would have resulted in zeroes in those bit positions However if the XOR result is zero that means that there are no ingredients that were Page 17 present in the library entry that were not present in the populated stock so the CAMS can make the cocktail indicated by that library entry If this algorithm determines that the cocktail can be made it populates the cocktail in the list of available cocktails Instead of performing a deep copy of all the fields of the drinkEntry structure and copying them to a new array the list of available cocktails called the menu is just an integer This integer indexes into the global library and pulls ingredient information from this library This algorithm is complex but it pro
49. ene 12 Hose Barb Y Splitter 0 91 1 0 91 Total Mechanical Cost 70 48 5 Lowes Home Improvement 2014 Adafruit Industries 2014 7 Lowes Home Improvement 2014 Table D7 Compressed Air System Module Costs Page 46 Component Name Price Total Mechanical Cost 70 48 Total Electrical Cost 63 18 Total Module Cost 133 66 Table D8 Single Valve Module Costs Component Name Price Total Mechanical Cost 40 17 Total Electrical Cost 63 18 Total Module Cost 103 35 Table D9 Price Comparisons Product Number of Total Cost Effective Cost Price Relative to Modules Per Module CAMS Cost CAMS 2 265 10 132 55 BoozeBot 2 683 81 341 91 257 95 CAMS 4 471 80 117 95 BoozeBot 4 1112 26 278 07 235 75 CAMS 7 781 86 111 69 Bartendro 7 2499 99 357 14 319 75 CAMS 8 885 21 110 65 BoozeBot 8 1283 64 160 46 145 01 Monsieur 8 3 999 99 499 88 451 76 CAMS 15 1608 68 107 25 Bartendro 15 3699 99 246 67 230 00 CAMS 16 1712 03 107 00 BoozeBot 16 1883 48 117 72 110 01 Page 47 Appendix E Experimental Results This Appendix contains the tables and graphs of raw data gathered from the experiments used to determine the accuracy of components used the CAMS Table El contains the data from the test to determine the mapping from ultrasonic sensor output pulse width to dis
50. ensor was tested over a range of 20cm which was chosen because the length of the bottle from end to end including the hose connector was 24cm Distance increments of one half centimeter were used so 40 data points were collected in total The results of this experiment can be found in Table El The datasheet for the ultrasonic sensor provided a formula for determining measurement distance as a function which is given in equation 1 time us 1 58 However my results found that the datasheet model was not quite accurate The slope of the line of data points was correct but at certain points the experimental data had slightly different constant offsets from the model Instead of relying on the datasheet model I developed a piecewise experimental model At all points in the experimental model the slope of the experimental model was the same as the datasheet model an additional 58 microseconds per centimeter However between 4cm and 7cm the plot was shifted down by 40 microseconds between 8cm and 21cm the plot was shifted down by 20 microseconds and between 21 5cm and 24cm the plot was shifted down by 55 microseconds The data for the experimental model can be found in Table El and a visual representation is found in Figure El As indicated in Table E2 the between percent error between the experimental data and the experimental model was very low The experimentally determined model was within 3 accuracy The mean squared error was 02
51. er devices either through the single row pin header on the side of the board for plugging into a breadboard or through a USB connection enabled by the serial communication chip and female USB B connector A green LED on the board useful for debugging can be connected to pin D 2 on the microcontroller through a two pin male pin header and a small jumper Similarly the pins that ordinarily drive the communication chip can be disconnected by removing jumpers on similar headers Serial communication jumpers were used on the CAMS for development purposes and for PC communication but the jumper for the green LED was removed On both the main and module boards the row of pin headers is plugged directly into a breadboard for easily interfacing with other components Please refer to Appendix B Schematics and Board Layout for references to the prototyping board UART Bus ATMEGA1284P microcontrollers have two separate UART channels On the main microcontroller UARTO is used to communicate with the PC to interact with the user while UARTI is used for the UART bus to communicate with all the module boards On the module boards UARTI is used for the UART bus and UARTO was left for PC communications for debugging purposes but is unused during normal operation The PC connection to the microcontroller is made possible by the serial communication chip an FTDI FT232RL chip which converts TTL level UART communication from the microcontroller to the differenti
52. esign section of this report calibration of the ultrasonic sensor and ingredient dispensing required calibration to yield accurate data For the ultrasonic sensor I ran an experiment to determine the accuracy of the sensor and to check the accuracy of the model on the datasheet I set up a microcontroller to initiate a sensor reading every 500ms and an oscilloscope was connected to the echo pin on the ultrasonic sensor so that the pulse width could be accurately determined A tape measure was taped to the laboratory bench and the breadboard with the microcontroller and ultrasonic sensor was clamped to the table A rectangular piece of aluminum was placed on the tape measure to attain a flat surface facing the ultrasonic sensor while being able to read the tape measure Basic initial experimentation indicated that the sensor was not accurate at distances closer than 4cm despite the data sheet indicating that the sensor was accurate to 2cm Between 4cm and 2cm the sensor would jump between readings holding the aluminum in one place would sometimes make the oscilloscope read one pulse width but would randomly jump between that reading and a few microseconds more Instead of trying to handle this sporadic behavior in software it is more reliable to impose a maximum fill line restriction on the bottle to ensure that the liquid is never closer than 4cm from the ultrasonic sensor After the lower bound on distance to sensor was determined the ultrasonic s
53. essage For example a program can format a message object to be a data message designated for another node on the bus the message can be queued to send as soon as it is ready and an interrupt flag can be raised when the transmission of the message is successful or if there is an acknowledgement error on the message The message object system of CAN controllers is complex but it allows for rich interactions between the software and the lower level protocol Originally it seemed as though the CAN bus was a good design choice for this project The high noise immunity offered by the bus specifications was attractive for this application Page 8 because the high power solenoid valves employed are likely to create noise on the bus The CAN bus is able to detect errors through analog bit errors on the bus packets formatting errors CRC errors and acknowledgement errors This wide set of error signaling could be useful in debugging to help get the technology running initially as well as in production runtime software to increase system robustness Additionally Atmel sells microcontrollers with integrated CAN controllers to reduce the circuit board complexity and allow direct manipulation of message objects and the status of the CAN controller Atmel also released several resources on how to program for the CAN line of microcontrollers and how to translate register names from other Atmel product lines to the CAN line Additionally because CAN packets cont
54. ftware and sets the flag prtintBytel high which is also used by the software The process of reading data out of the receive buffer clears the interrupt flag so multiple ISRs do not trigger from a single byte of data Communication The main loop of the module board simply calls a communication function which executes the module side of the handshake Inside this function the printBytel flag is polled If the flag is high that means there is new data to evaluation in the readDatal variable In that case the flag is cleared and the data is checked against the stored address If the data does not match the stored address then the module board turns off the UART transmitter to prevent it from driving the bus when it was not the module being addressed If the data matches the stored address the software first enables the UARTI transmitter waits for the transmit buffer to be empty and acknowledges the address by sending the address back on the bus If the next byte received matches the address again another acknowledge is sent This allows the handshake to be reset without timeouts retries or signaling to the main board when a reset occurs If the address doesn t match on a byte directly following a correct address it is assumed that this is a command byte so the number of parts of the ingredient to dispense is stripped out from the message by taking the lower order 6 bits and subtracting 0x20 Once the number of parts has been successfully stripped
55. h low level software If a handshake with a module fails then the main board retries twice more Testing the bus reliability while pulling to ground revealed that the UART bus timing is able to correct itself without any software intervention The byte transmission is successful on either the second or the third try A successful full drink ordering process on a system where the bus is pulled to ground can be found in Figure A2 Valve Calibration Tests As discussed in the Mechanical Design section of this report a direct mapping from liquid height in the container to duration to hold the valve open was created instead of a mathematical model of the flow rate Determining this mapping was done in two steps First a characterization experiment was run to obtain a rough estimate on the flow rate at each height The results of this experiment were analyzed to estimate a duration to hold the valve open for at each liquid height Another experiment was run in which the valves were held open for the estimated amount of time and the number of mL of water dispensed was recorded Based on the data from the first two experiments another estimate was determined and the second experiment was repeated This process continued for 1 additional run until the correct valve duration was determined The results of the characterization experiment can be found in Table E3 and the results of the estimation experiments can be found in Tables E4 The final mapping of liquid
56. h of the plastic bottle the experimental model was within 3 accuracy This model was computationally simple so it did not hinder performance Interfacing with the ultrasonic sensor presented an interesting challenge The hardware timers on the microcontroller have the feature of being able to detect a logic level change on a pin and immediately stop the timer called the Interrupt Capture Unit This feature is useful for Page 21 determining pulse width but only when the start time of the pulse is known To initiate the sensor reading the microcontroller needs to send a pulse of at least 10 microseconds called the trigger pulse to the sensor s trigger pin The sensor sends a series of ultrasonic pulses to determine distance then at some point later the output also known as the echo pulse starts The datasheet does not provide any references for knowing when the echo pulse starts with respect to the trigger pulse Either the Interrupt Capture Unit would have to be configured to trigger on pulse edges of the echoed pulse or the interrupt would only be triggered on the falling edge and the sensor would have to be recalibrated Instead Timer 1 was used in conjunction with an edge transition pin interrupt on pin C2 separate from the timer interrupts Whenever a command is received to dispense an ingredient and sensor reading was initiated by putting an 11 microsecond pulse on pin C3 by using the delay us function from util delay h This is
57. having an LED very near to a phototransistor and isolating both from any other light source This allows a microcontroller to control the voltage of the phototransistor in an analog manner usually through pulse width modulation The module board microcontroller is connected through a current limiting resistor to the anode of the LED inside the opto isolator The CAMS only needs the valve to be either turned on or off so instead of putting an analog voltage on the LED the LED is either provided 5V or 0V When the LED is not turned on the 10kQ is weakly pulling the gate of the NFET to ground which causes it to not conduct No voltage is being dropped across the solenoid so the solenoid is turned off When the LED is turned on the phototransistor is conducting which strongly pulls the gate of the NFET to valve power minus threshold voltage of the phototransistor This turns on the NFET which causes the negative terminal of the solenoid to effectively be at ground which results in a 6V drop across the solenoid turning it on There is a diode connected to the terminals of the solenoid used to prevent inductive spikes when the solenoid first turns on or off There is also a capacitor located on the terminals of the solenoid to prevent high frequency noise spikes Mechanical Design Due to limited development time a complete mechanical design and structure had not been completed Some preliminary mechanical designs had been drafted but wer
58. height to valve duration can be found in Table E4 The first experiment run was the characterization experiment In this set up the ingredient bottle was filled to 4cm below the top of the bottle with water and the valve was periodically held open for a constant amount of time and the volume of liquid measured in mL was measured On each measurement the starting height of the liquid was measured and the liquid was dispensed into a graduated cylinder This experiment was run three times and the results can be found in Table E4 Originally I intended to average over three runs and use that average as a basis for my estimation However the first two data sets were inconsistent while the third data set was self consistent and consistent with the expected results from Bernoulli s Principle that a taller height of volume gives a higher flow rate at constant pressure In each of the data sets a few points had to be thrown out due to fidelity of data Either some of the water had spilled and so an accurate volume could not be determined or the distance was not measured properly prior to dispensing Regardless of these omitted data points plotting the first two data sets with a linear trend gives very poor correlation with the data whereas plotting a linear trend line from the third data gives strong correlation Page 24 Instead of taking an average over all three of these data sets a trend line is formed using the last data set The measurement of
59. ined modules which each control the dispensing of one liquid cocktail ingredient Ice garnishes and any other non liquid cocktail components must be handled by the bartender before delivery to a customer The central board is a single circuit board with a microcontroller but the modules consist of a circuit board a solenoid valve and associated driving circuitry a 700mL water bottle with a hole cut in the top an ultrasonic sensor mounted on top a set of tubes and connectors to connect the bottle to the valve and then the valve to outgoing tubing an a wooden housing to hold all of these components Please refer to Appendix B Schematics and Board Layout for detailed schematics and layout of the boards and circuitry used in the CAMS Prototyping Circuit Board The main and module boards both use the same prototyping circuit board known as a breakout board This board is an existing design for prototyping systems using an ATMEGA 1284P microcontroller and peripheral hardware for a wide range of prototypes The power input on the board takes unregulated 7V to 35V and converts it to a regulated 5V to power the remainder of the board The ATMEGA1284P is seated in a DIP socket on the board that allows the chip to be swapped out if it breaks or is damaged The microcontroller is programmed using an on board ISP header An external 16MHz crystal provides the system clock through the XTAL pins on the microcontroller The microcontroller communicates with oth
60. ing automation system Page 31 References Adafruit Industries 2014 Full Sized Breadboard Retrieved from adafruit com http www adafruit com products 239 Advanced Circuits 2014 2 Layer PCB Designs Retrieved from 4pcb com http www 4pcb com 33 each pcbs index html Advanced Circuits 2014 BareBones Printed Circuit Boards Retrieved from 4pcb com http www 4pcb com bare bones pcbs index html All Electronics Corporation 2014 2 x 40 Pins Snappable Headers Retrieved from allelectronics com http www allelectronics com make a store item dhs 40 2 x 40 pins snappable headers 1 html Digi Key Electronics 2014 Electronic Components Listing Retrieved from digikey com http www digikey com product search en HC SR04 Ultrasonic Sensor 2011 May 10 Retrieved from Elec Freaks http www elecfreaks com store hcsr04 ultrasonic sensor distance measuring module ultra01 p 91 html Hobby King 2014 Ultrasonic Module HC SR04 Arduino Retrieved from hobbyking com http www hobbyking com hobbyking store 31136 ultrasonic module hc sr04 ardui no html Ultrasonic Ranging Module HC SR04 n d Retrieved from micropik com The Art of Components http www micropik com PDF HCSR04 pdf United States Plastics Corporation 2014 Tubing Hose and Fittings Retrieved from usplastic com http www usplastic com catalog default aspx catid 8568parentcatid 1 Lowes Home Improvement 2014 Genova 1 2 in Dia Insert Elbow Retrie
61. king is performed on the item number and if it passes then that number is used to index into the menu array that stores indexes into the global library For example if the cocktail Gin and Tonic is labeled menu item number 46 but is overall drink number 238 then a user attempting to order a Gin and Tonic would enter 46 on the terminal Element 46 in the menu would be accessed and that value would be 238 238 would then be used to index into the global list of all cocktails and that would indicate the ingredients in a Gin and Tonic and the cocktail name and ingredients would be printed to the serial terminal for verification The CAMS would then issue commands to the appropriate modules and respond with a success message when the dispense commands have been acknowledged by all relevant modules Similar to the module population entering cocktail 100 forces a software reset of the CAMS through a watchdog timer overflow Communication Stack The CAMS implements a basic communication stack with UART at the physical level to handle transmission of messages and receipt of acknowledges on the bus This is a three level stack which means there are three levels of function calls before data is actually loaded into transmit buffers This protocol is not knowingly modeled after any existing protocol it was created to avoid having one monolithic communication function with a complicated error signaling scheme Failures at different levels of the protoc
62. l of the bottle combined with a poor model of the pressure drops in the valve tubes and connectors would lead to a very inaccurate dispensing of ingredient from the bottle No analytical solution could be reached so the problem of determining how long to hold the valve open for was empirically determined Ultimately the goal was to find a way to determine the volume in the bottle which could then be used to find the flow rate which in turn gives a duration of time to hold the solenoid valve open for the dispense the correct amount of liquid However since no accurate expressions could be found for any of the intermediate steps an experimental mapping from the height of the liquid in the bottle to duration of time to hold open the valve to dispense a particular volume of liquid was developed This was a very slow process but a discussion of the experiment is found in the Results section of this design report The mapping of liquid height to amount of time to hold the valve open was used instead of mapping height to flow rate because determining how long to hold the valve open as a function of flow rate is difficult As the valve is held open the height of the liquid changes and so either the height is going to have to be dynamically calculated or reread from the sensor Both of these schemes would make the dispensing process slow so a mapping of liquid height to duration to hold the valve open is used Determining liquid height is done by an ultr
63. lve is held open is as accurate as possible Even with this rounding scheme the estimated values are within 5 accuracy Based on the results of the first run a second run was conducted to get a better estimate for a 22mL valve duration To arrive at the second estimates the difference between the dispensed and desired volumes was divided by the slope of the flow rate graph from the characterization experiment and was added to the valve durations from the first run The goal of this was to try to add the exact amount of time needed to compensate for the undershoot of the first run This was a valid method because no volumes dispensed in the first run were greater than 22 mL Estimates for the first data run generally were less than 22mL but were sporadic Only 10 out of 27 dispensed volumes were within 1 mL of 22 mL for the first run whereas 21 out of 26 volumes were between 21 mL and 23 mL An even more accurate mapping could be determined by further by iterating the process of determining an average flow rate determining the difference between desired and measured volume dispensed and adjusting the duration for each distance These estimates were carefully formulated and demonstrated that a linear equation could not be used to determine valve duration However further iterations were not pursued because the limited accuracy of the measurement system would eclipse the inaccuracy of the valve durations During the estimation experiments the bottle w
64. ly prepares cocktails for patrons at a bar or restaurant This systems consists of a central processing board that handles user requests and coordinates communication among modules which each hold one ingredient A module consists of a plastic bottle an ultrasonic sensor a valve a group of tubes and connectors a structure to mount these components and a microcontroller board with associated circuitry to run the module components Some tasks needed to run a bar cannot automated so this system is intended to complement or replace bartenders for easy to mix beverages Preparing more advanced cocktails collecting payments swapping out bottles and many other tasks must still be carried out by trained bartenders Turning on the CAMS begins the setup process Using a serial terminal the CAMS prompts for which ingredients are located in each ingredient module These ingredients are encoded by number so this process requires the user to know the mapping from ingredient names to ingredient numbers Once the modules and contents have been enumerated it prints a list of all the cocktails available to be made and then prompts the user to select a cocktail to be made The CAMS delivers beverages by acting in two stages order determination and component delivery First a user orders a cocktail from the presented list by menu item number which was just displayed Then for each ingredient in the cocktail the CAMS determines what module the ingredient is lo
65. module 0 uccess ransaction complete hat drink would you like to order o o StupodrPprHtanps pH Figure A2 Example Successful Ordering Sequence Using a Grounded Bus Page 35 Appendix B Mechanical Design Figure B1 Front Mechanical View of a CAMS module Page 36 Figure B2 SolidWorks Model of Mechanical Structure Page 37 Appendix C Circuit Board Schematics and Design The design and layout for the ATMEGA 1284P breakout board is taken with permission from Nathan Chun nic4 and Bruce Land brl4 The board schematic and design can be found in the design report for the board Chun 2010 The schematics found below are the full schematics for both the main and module boards The schematics do not indicate which components are on the breakout board and which are external Please refer to the breakout board design schematics for a reference for on board components Tables D2 and D3 in Appendix D contain a listing of all parts used on each board Figures C1 and C3 contain schematics of the main and module boards and Figures C2 and C4 contain pictures of the constructed circuits respectively Figure C5 contains the schematics of the CAN Bus breakout board that was designed but not used in the prototype Page 38 Power Circuit 8 Serial Communications m1 MCU Bypassing Caps LS XTAL Circuit ISP Header ATMEGA1284P PU Figure C2 Constructed Main Board Page
66. nd 0 2 0 0 0 0 1 Coke Potpourri 1 1 1 1 1 1 1 Gin and 0 0 1 0 1 Juice Cherry 0 0 0 1 0 2 0 Schnapps Page 33 Starting What is in slot 0 4 What is in slot 1 6 What is in slot 2 2 What is in slot 3 5 What is in slot 4 0 What is in slot 5 99 Have vodka in slot 4 gin in slot 2 orange juice in slot 0 grenadine in slot 3 coke in slot 1 Current Menu Item 0 Screwdriver 1 parts vodka 2 parts oj Item 1 Gin and Juice 1 parts gin 1 parts oj What drink would you like to order 0 You have selected 0 Screwdriver 1 parts vodka 2 parts oj This drink needs 1 parts of vodka which is located in module 4 ttempting to request 1 parts from module 4 uccess ransaction complete his drink needs 2 parts of oj which is located in module 0 ttempting to request 2 parts from module 0 uccess ransaction complete hat drink would you like to order ztu parton p Figure Al Example Successful Serial Console Output Page 34 What drink would you like to order 0 You have selected 0 Screwdriver 1 parts vodka 2 parts oj his drink needs 1 parts of vodka which is located in module 4 ttempting to request 1 parts from module 4 response ttempting to request 1 parts from module 4 uccess ransaction complete his drink needs 2 parts of oj which is located in module 0 ttempting to request 2 parts from module 0 response ttempting to request 2 parts from
67. nected to another hose barb to NPT connector which is connected to 2 of tubing The tubing is also connected to a polypropylene 90 elbow with a hose barb connector on both ports Tubing then connects this elbow to the dispensing area near the cocktail glass Many of the connectors are sealed with Teflon pipe thread tape to prevent leaking between threads Additionally the inside of the female garden hose to 1 2 hose barb connector is coated in a thin layer of silicon grease to prevent leaking and has an extra gasket to improve the seal between the connector and the ingredient bottle Page 14 Accurately dispensing a certain volume of liquid out of the bottle requires holding the valve open for a specific duration which is based on the flow rate The flow rate out of the bottle is not constant it is governed by Bernoulli s Principle An ultrasonic sensor seated in a hole cut out at the top of the bottle can measure the height of the liquid in the bottle which can in turn be used to determine flow rate However the flow rate can be difficult to calculate because the shape of the bottle makes modeling volume as a function of height difficult Even if an accurate volume model could be determined and evaluate determining flow rate would also be difficult The exact material properties and physical dimensions of the connectors and valve are not known so the pressure drops and thus the flow rate in the system are difficult to model Instead
68. necting direct as following 5V Supply Trigger Pulse Input Echo Pulse Output OV Ground Electric Parameter Working Voltage DCSV Working Current I5ma Working Frequency 40m2 Max Rage fm Min Range MeasuringAngle Trigger Input Signal 10uS TTL pulse Echo Output Signal Input TTL lever signal and the range in proportion 45 20 15mm Page 54 Vee Trig Echo GND Timing diagram The Timing diagram is shown below You only need to supply a short 10uS pulse to the trigger input to start the ranging and then the module will send out an 8 cycle burst of ultrasound at 40 kHz and raise its echo The Echo is a distance object that is pulse width and the range in proportion You can calculate the range through the time interval between sending trigger signal and receiving echo signal Formula uS 58 centimeters or uS 148 inch or the range high level time velocity 340M S 2 we suggest to use over 60ms measurement cycle in order to prevent trigger signal to the echo signal 10uS TTL Timing Diagram Trigger Input to Module 8 Cycle Sonic Burst from Module Input TTL lever Echo Pulse Output signal with a range to User Tumeing Circuit in proportion
69. not as accurate as using a hardware timer because the delay function does not account for time to execute ISRs but it was simpler than setting up a microsecond time base ISR The sensor is triggered by anything larger than a 10 microsecond pulse so attempting to send an 11 microsecond pulse that is elongated by an ISR is acceptable After the microsecond delay is finished an edge triggered interrupt on pin C2 is enabled and the software waits until pin C2 goes high and then low again indicating a full pulse has occurred On the rising edge of the echo pulse the edge triggered ISR is entered and Timer 1 is cleared and started with a prescalar of eight giving a 0 5 microsecond time base At the falling edge of the pin interrupt Timer 1 is stopped to get the time between when the start pulse was sent and when the echo was received The resulting time is then converted to twice the distance in centimeters and rounded to get an effective rounding to the nearest 0 5 centimeters This result is then used to index into a table of valve durations As discussed a mapping from liquid height to number of milliseconds to hold the valve open was experimentally determined Ultrasonic readings are rounded to the nearest 0 5 centimeters so the table of valve durations must has an entry for each 0 5 centimeter The ultrasonic sensor data sheet claims the sensor is accurate to 0 3 centimeters but it is safer to not approach the maximum accuracy bounds The discussion
70. of the valve experiments can be found in the Results section of this report The end result of these experiments is that for each 0 5 centimeters increment the CAMS module microcontroller knows how long to open the solenoid valve for in order to dispense one unit 22mL of liquid Despite the experimentation and data analysis that was part of the design process the final process for dispensing an ingredient is very simple First a reading of the ultrasonic sensor is initiated and read Next the value from the sensor reading is converted to a distance in centimeters which is then rounded to the nearest 5 centimeter This is stored as a number twice as big because indices of an array must be integers This number is combined with the number of parts units of volume to dispense and indexed into a table to determine how long to hold the valve open for Lastly the microcontroller drives pin CO the pin connected to the opto isolator discussed previously in Electrical Design high for the specified number of milliseconds to open the valve and start dispensing liquid Hardware timer 0 is used as a millisecond time base and after the specified amount of time the pin is driven low to shut off the valve If a cocktail requires multiple parts of the same component the module board waits for 500 milliseconds for the valve to settle and repeats this process for each part of liquid to dispense Page 22 Results Sensor Experiments As discussed in the D
71. ol indicate different messages to help diagnose issues When a cocktail is ordered the orderDrink function is called with the global drink number as the argument This function iterates through the allBits field of the drinkEntryUnion to determine if the cocktail needs that ingredient This is done by saving the allBits field into a Page 18 variable called selectedDrinkBits forming another variable called numParts that is an AND of the selectedDrinkBits and the number 3 If the AND is zero that means that ingredient number 0 is not used in this cocktail The ingredient number is incremented by 1 and selectedDrinkBits is right shifted by 2 to move to the next ingredient If the AND is non zero that means that the cocktail needs the current ingredient so a message should be formed to the relevant module Again the ingredient number is incremented and selectedDrinkBits is shifted right by 2 This process is repeated for all of the ingredients in the ingredient list This bit math could be avoided by spelling out the process directly for each ingredient but this would cause the code size to inflate because there would be several lines of code for each module instead of a slightly larger number of lines for all modules Also if each module was listed directly adding any ingredients to the list would cause further code size increase For each ingredient that is needed by the cocktail a command is attempted to be sent to the module to dispens
72. onnector and held upright by the ingredient bottle assembly above A model of this module design can be found in Figure B2 This prototype is not the optimal structure for the CAMS but it does have some key design points that a proper design should have The current structure has an adequate way to hold the weight of the ingredient bottle and the valve which constitute the majority of mass of the module and provide the greatest load on the structure Additionally it would be incredibly difficult to knock over or disturb this prototype which makes it safer for a hectic bar environment However there are three major design flaws which need to be addressed The first is that the box structure is not specifically designed for the CAMS so it is large and unwieldy Constructing a fifteen module CAMS with this structure would require nearly seventeen feet of counter space The boxes are easily stackable but it would be difficult to restock the ingredients inside A good design would be much thinner and lighter so that many modules does not take up significant counter space while also being stackable to further consolidate linear space usage A better designed structure would also have an easier way to attach the necessary wires Either the structure would have a hole in the back or sides to string wires through or would have connectors mounted on the side to easily plug in the module board to valve sensor electronics Depending on the connectors used the wir
73. oss all systems including CAMS the greater number of modules purchased the cheaper the effective module price as cost of the main controller is distributed over many modules The most expensive and least cost effective product is the Monsieur which has a rate of 500 per module and the most cost effective per module is the BoozeBot which costs 62 5 British Pounds or about 108 The CAMS prototype has a per module cost of 103 35 The cost of the largest BoozeBot system is more than the cost of an equally sized CAMS even when taking into account the costs of the main module A four module CAMS prototype is expected to cost 57 5 cheaper than the same size BoozeBot which is the smallest model Furthermore the prototype cost of the CAMS was driven up significantly by the debug hardware used and buying each part individually Some components such as the FTDI serial chip the associated capacitors and USB connector totaling about 5 50 are not needed for production model module boards because the USB connection is used only for debugging For a production board the microcontroller would be mounted directly on to the board Future development work with the CAMS past the first prototype can also likely lead to additional cost efficiencies in the design It is likely that the code size and timer hardware requirements of the CAMS could be satisfied by a smaller cheaper microcontroller which would also remove cost of the system Designing custom ci
74. ot reduce the cost enough to validate use of the design Regardless requiring an extra board for every multiple of 4 modules used past 5 will unnecessarily drive up the total system cost which defies one of the principal design points of the CAMS CAN Bus Communications Structure The main alternative design choice for the board to board communications infrastructure considered was the CAN Controller Area Network protocol for bus communication The CAN standard is a bus based protocol that was developed at Bosch in the 1980 s and has been used primarily for automotive systems CAN is a bus based multi master protocol similar to PC in that any node can send a message to any other node on the bus Each node on the bus is assigned a unique identifier determined at design time which also denotes priority on the bus A lower numbered identifier denotes higher priority A CAN packet consists of many fields including up to 8 bytes of payload and a 15 bit CRC field for error detection Additionally CAN has a wide variety of error detection and information to convey to software The CAN protocol is interesting because it requires two separate controllers to operate the protocol One controller handles the logic of the protocol and communicates with the second controller which handles the analog specifics of the CAN bus including performing processing and error detection tasks at the bit level There are two versions of the CAN protocol currently in use
75. out an acknowledge message of the command is sent The command acknowledge contains just the number 128 and once this is sent then the UART transmitter is turned off to prevent the module board from driving the bus unnecessarily This concludes the handshake on the module board side However once the command has been acknowledged the module board must open the solenoid valve for the appropriate amount of time to dispense the specified liquid This is done by calling valveDuration which will be discussed in the following paragraphs Once valveDuration terminates the module board communication function returns to a state where it waits for an address message from the main board Page 20 Ultrasonic Sensor and Valve Control Once a module receives a command to dispense a certain volume of liquid then the module must then open a solenoid valve to dispense the liquid out of the plastic bottle The flow rate of the ingredient out of the bottle is a function of the amount of liquid in the bottle so an expression relating liquid volume and flow rate must be reached However the exact expression for determining flow rate as a function of volume is difficult for several reasons First it is difficult to determine the volume in the bottle because the shape of the bottle is not easily modeled Next the valve combined with the tubes and connectors makes the pressure drop calculations difficult due to my inexperience in fluid mechanics A poor physical mode
76. rcuit boards for this system would eliminate the need for any breadboards currently used which each cost 6 Lastly purchasing all system components and circuit boards in bulk would drastically reduce cost per module as the prototype cost was determined by individual part costs of every single electrical and mechanical component in the system Page 6 Alternative Designs Considered Over the course of this design project several design alternatives were explored to best suit the needs of the CAMS These design choices demonstrated tradeoffs in cost system complexity and required development time The possible design alternatives were grouped into two categories communications structure and beverage dispensing methods For each of these categories the design possibilities that were not chosen will be discussed while leading up to a description of the final design Communications Structure Custom Static Network The first network structure that was considered required a custom protocol and network topology There were three types of network nodes in this topology the central board interface boards and the beverage modules and these nodes formed a quad tree structure The central board forms the root of the tree and thus has four ports the interface boards each have one port to connect to its parents and have four ports for four branches and the modules just have a single port At initialization time of the system the central board a
77. rd software sends and receives messages on the UART bus as well as reads the ultrasonic sensor to control the solenoid valve actuation For a full software listing please contact cig23 cornell edu Data Structures In order to efficiently store and reference cocktails that the CAMS can make a complex data structure was created to store the cocktail information in a memory efficient manner while also enabling fast lookup functions for the library of cocktails At the lowest level of the structure drinkEntryBits is a collection of two bit fields in a C struct Each two bit field corresponds to a particular ingredient that the CAMS knows how to use and the number in the field represents how many parts of that ingredient go in a cocktail For example if a cocktail had zeros s in all of its drinkEntryBits entries except a one in the Rum field and a two in the Coke field then that cocktail would call for one parts Rum to two parts Coke The drinkEntryBits structure currently only has seven entries defined although this can be easily expanded to incorporate new drinks by adding additional entries in the struct definition and in all places where the struct is called The drinkEntryBits struct is embedded in a C union called drinkEntryUnion with an unsigned 16 bit integer The purpose of this union is to allow setting and clearing of all the fields in the entry at once without having to enumerate each individual entry A 16 bit integer is used
78. re success or if the sending process never completes At the lowest level of the communication stack is the process of attempting to send an individual message to a module A message is successfully sent if a short messaging handshake is completed First the uartSendByte function records how many seconds since system initialization have elapsed as indicated by the variable from the millisecond time base ISR Next it waits until the UARTI transmit buffer is empty and then it sends a byte with a value of 0x30 or 48 plus the module number over the bus The increment is added to the module number of avoid ambiguity between module addresses and commands After the address is transmitted the function then transitions to a state of waiting for an address acknowledge If a message is received that is not an address acknowledge from the correct module the function returns false If the address acknowledge is correct then the function waits until the transmit buffer is empty again and then the number of parts to dispense is sent over the bus One part of liquid refers to half shots or approximately 22mL The function that transitions to a state of waiting for the command acknowledge If the command acknowledge byte which has value 128 is received then the handshake is complete the sending of the message was a success and the function returns true However if the whole handshake takes more than 50 milliseconds before finishing as indicated Page
79. rial connection hardware costs 5 40 Removing other unused components such as the debug LED unused port pins and other assorted breakout pins and jumpers saves only about 0 25 Removing all debug hardware and the whiteboard in total would save 12 11 on total module costs Both removing debug hardware and updating the circuitry buying in bulk saves 19 26 per module which is an overall savings of 18 60 per module Page 27 Aside from reducing circuitry on the boards purchasing circuit boards in bulk can significantly save on the cost It is impossible to know exactly how much purchasing a circuit board in bulk would cost until the entire board is designed A board redesign cannot begin until a new set of parts is selected After that the debug hardware would be removed from the prototype board the new parts would be added and additional utility would be added to make the product more robust Instead of mounting the board on a whiteboard screw holes could be added to physically mount the board to the structure of the module Additionally the existing UART bus is a set of wires plugged into breadboards so a proper method of constructing an arbitrarily sized bus must be designed then incorporated into the new circuit board design After the board design is updated to be used on a proper product the circuit boards can be ordered in bulk to reduce costs Advanced Circuits a PCB manufacturer offers a calculator for estimating board price for a
80. rk on smartphones The ad hoc network would replace the Smartphone applications can be turned on and off at any time so the Bluetooth network needs to be able to handle many users coming online and going offline frequently Other communication technologies can potentially be used but Bluetooth is very attractive for the CAMS because only a single Bluetooth module needs to be used for the entire system and most smartphones come packaged with a Bluetooth module Also because there aren t many other Bluetooth devices that would be used in a bar it is likely that there wouldn t be any competition for resources with the Bluetooth module A user might be trying to send data over the cellular network or use WiFi on their phones at any time but Bluetooth is only used for a few types of uses and those uses are generally orthogonal to the CAMS so the CAMS would have sole use of the Bluetooth module Page 30 Conclusions At the time of submission of this design report a small scale CAMS prototype can been successfully constructed and tested in the laboratory This prototype contains one fully constructed module with the ingredient bottle valve assembly and ultrasonic sensor mounted and functioning together A second development module is also in use that does not have a structure built but also has a valve and ultrasonic sensor connected properly that function in the same manner as the first module Extensive experiments were conducted to characterize th
81. rty Robotics 2014 Retrieved from partyrobotics com http partyrobotics com The Inebriator 2014 The Inebriator Arduino Powered Cocktail Machine Retrieved from theinebriator com http www theinebriator com Appendix A Software and User Interface This Appendix contains a reference for the user interface of the CAMS Table A1 shows the mapping from ingredient number to ingredient name which is used during initialization to specify what ingredients are in each module Only a limited number of cocktails were used for prototyping the CAMS but a listing of the cocktails used and their respective recipes is contained in Table A2 Figure A1 shows an example sequence for a successful initialization of the CAMS and the ordering of a single cocktail Figure A2 shows a successful ordering process where the system uses a bus that is pulled to ground instead of to 5V For a complete listing of the software of the CAMS please contact cig23 cornell edu Table AI List of Ingredient Numbers and Names Ingredient Number Ingredient Name 0 Vodka 1 Rum 2 Gin 3 Peach Schnapps 4 Orange Juice 3 Grenadine 6 Coke Table A2 List of Cocktails Cocktail Number Number Number Number Number Number Number Name of Parts of Parts of Parts of Parts of Parts of Parts of Parts Vodka Rum Gin Peach Orange Grenadine Coke Schnapps Juice Screwdriver 1 0 0 0 2 0 Rum a
82. ssed Air It was apparent that the conveyor belt system was not the optimal design choice so additional design choices were explored Another such choice was to use a system of compressed air and tubes to be able to dispense ingredients from modules that were physically distant This design requires many mechanical components First the system would require a compressed air tank and a method of delivering the compressed air to the beverage modules This method also has to allow air flow control from the beverage modules as well as a way to control the dispensing of liquids out of the modules None of these pose particularly difficult mechanical challenges The regulator output of a compressed air tank is a National Pipe Thread NPT standard so the tank can be easily interfaced with a variety of beverage safe plastic standard connectors tree of tube splitter components such as Y and T splitters could be used to deliver compressed air to tubes for each of the modules and the fluid flow could be controller by a microcontroller by using a solenoid valve and appropriate driving circuit Another solenoid valve could be used to dispense the liquid from the module itself A minor amount of coordination software would be required by the module boards but having one dedicated valve for liquid dispensing and one for compressed air would make the coordination relatively simple The valve and tubes solution had many advantages for the CAMS First this design
83. stal CTS Frequency Controls MP160 0 66 Green LED Lumex Inc SSL LX5093PGD 055 Opto isolator Lite On Inc 4N35 0 43 DIP Socket Assmann WSW A40 LC TT 0 51 Components UART USB Future Technology FT232RL REEL 4 50 Converter Devices Limited 5V Regulator Texas Instruments LM340LAZ 5 0 NOPB 0 95 USB B Socket On Shore Technology USB B1HSB6 0 54 Inc Single Row Male Pin Molex Inc 0022284360 0 00356 pin Header Dual Row Male Pin All Electronics DHS 40 0 0375 row Header Microcontroller Atmel ATMEGA 1284P 7 75 2 1mm Power Jack CUI Inc PJ 002A 0 93 Ultrasonic Sensor Hobby King HC SR04 2 89 SPDT Switch C amp K Components AYZO10AGRLC 0 91 White Breadboard Adafruit 239 5 95 Custom PCB Advanced Circuits N A 33 All Electronics Corporation 2014 Hobby King 2014 a ci 3 Adafruit Industries 2014 4 Advanced Circuits 2014 Page 42 Table D2 Main Board Components Page 43 Component Name Unit Cost Quantity Total Price Diode 0 11 1 0 11 10kQ Resistor 0 08 1 0 08 3300 Resistor 0 08 2 0 16 1000 Resistor 0 08 1 0 08 luF Capacitor 0 20 2 0 40 100nF Capacitor 0 10 5 0 50 10nF Capacitor 0 12 1 0 12 4 7nF Capacitor 0 14 1 0 14 22pF Capacitor 0 16 2 0 32 16MHz Crystal 0 66 1 0 66 Green LED 055 1 055 DIP Socket 0 51 1 0 51 UART USB 4 50 1 4 50 Converter 5V Regulator 0 95 1 0 95 USB B Socket 0 54 1 0
84. t volume of that ingredient is needed A command is issued to each of the relevant modules to dispense the specified ingredient The modules all dispense ingredients into plastic tubing that runs from the modules to a cocktail glass There are several other existing solutions currently on the market These systems also offer complete hardware software solutions but none of these systems are cheap modular or scalable They all require the purchase of a specific sized system and if at a later point more modules are desired for the system an entirely new system must be purchased with no way of using the existing system The CAMS is designed to use as few as 1 ingredient module and as many as 64 ingredient modules The main controller is separate from the ingredient modules and the ingredient modules only need connections to power and to the communications bus to add functionality to the system Additionally the expected cost of the CAMS is significantly lower than the existing systems per module The CAMS cost efficiency varies slightly with number of modules as the cost of the main module must be paid regardless of system size However the CAMS is more cost effective than all other existing systems for all system sizes Page iii Executive Summary The purpose of the Cocktail Automation Management System CAMS is to offer a complete hardware software system that automatically prepares cocktails for patrons at a bar or restaurant This systems
85. tance in centimeters along with the model from the datasheet and experimentally determined model Figure El graphs these results for a visual representation of the models Table E2 gives the calculated percent error between the two models and the data gathered from the experiment Table E3 contains the data from the first valve experiment where the valve was held open for a constant duration and the dispensed volume was measured as function of liquid height in the ingredient bottle Figure E2 graphs these results and plots the trend line of the most accurate data set Table E4 contains the data from the two runs of the experiment to determine the duration of time to hold the valve open to dispense 22mL Table EI Results of Ultrasonic Sensor Test Measured Sensor Experimental Model Distance cm Measured Pulse Width Datasheet Model 4 194 232 192 4 5 222 261 221 5 248 290 250 3 2 278 319 279 6 306 348 308 6 5 330 377 337 7 360 406 366 7 5 408 435 415 8 432 464 444 8 5 464 493 473 9 492 522 502 9 5 532 551 531 10 572 580 560 10 5 604 609 589 11 636 638 618 11 5 644 667 647 12 692 696 676 12 5 696 725 705 13 728 754 734 13 5 756 783 763 14 784 812 792 14 5 812 841 821 15 840 870 850 15 5 868 890 879 16 890 928 908 Page 48 16 5 920 957 937 17 950 986 966 17 5 980
86. ttempts to enumerate all of the modules that are present by querying each of the ports one by one to list the connected modules The result of this process is that the main board and the interface boards all know which beverage modules are located at each of their ports but do not know the exact locations of the modules For example the main board might know that there are seven modules that branch off of port zero but does not know their exact locations If the main board wants to send a command to one of those seven modules it sends a request to that port and allows the connected interface boards to handle the request When an interface board gets a request for module dispensing it repeats the process If the desired module is located at one of the ports with just a leaf on it then the interface board knows the exact location of the module If the module is located at the port with the next interface board it just sends a command to dispense an ingredient and allows the next level board to handle the request The key aspect of this design is that all of the ports are physically the same pin out and the protocol for requesting commands and responding to commands is the same regardless of whether or not the receiving node is an interface board or a module This provides two main benefits First using the same message standards for sending and receiving from both boards and modules makes the communication software very easy When a board gets or gener
87. ved from lowes com http www lowes com pd 22520 322 350705 0 productld 3455100 amp Ntt Lowes Home Improvement 2014 Watts 3 4 in x 1 2 in Threaded Adapter Fitting Retrieved from lowes com http www lowes com pd 416836 104 LFA 684 0 Ntt Ifa 684 amp UserSearchzlfa 684 amp productld23824549 amp rpp 32 Adafruit Industries 2014 Brass Liquid Solenoid Valve Retrieved from adafruit com http www adafruit com products 996 Atmel Corporation 2009 November ATmega1284P Datasheet Retrieved from atmel com http www atmel com images doc8059 paf Land B 2013 ECE 4760 Lab 4 Retrieved from Cornell University ECE 4760 Designing with Microcontrollers http people ece cornell edu land courses ece4760 labs f2013 lab4 html Chun N I 2010 May Electrical and Computer Engineering Projects Masters of Engineering and Undergraduate Independent Study Retrieved from Next Generation Atmel ATMEGA644 Prototype Board http people ece cornell edu land courses eceprojectsland STUDENTPROJ 2009to2010 nic4 Writeupv5 pdf BoozeBots 2014 BoozeBot The Automated Cocktail Dispenser Retrieved from kickstarter com https www kickstarter com projects boozebots boozebot the automated cocktail dispenser Bosch 1991 September CAN Specification Retrieved from bosch semiconductors de http www bosch semiconductors de media pdf 1 canliteratur can2spec pdf Monsieur 2014 Retrieved from monsieur com http monsieur co Page 32 Pa
88. vides many benefits First using the allBits field in the drinkEntryUnion within the drinkEntry structure requires that only three operations are needed to determine if a cocktail can be made regardless of the number of possible ingredients there may be If each ingredient is checked individually via a method such as iterating through each ingredient and checking if the library entry needs the ingredient and the ingredient is in stock then the lookup time for each module would scale linearly with the number of possible ingredients Similarly performing a deep copy from one array of drinkEntry structures to another would also scale linearly with the number of ingredients The time saved may not matter for small scale systems but when a CAMS is trying to serve hundreds of patrons in a bar then saving time only having to perform 3 operations total instead of 3 per ingredient plus the time to perform a memcpy may be relevant Unfortunately it is not possible to determine the time savings without programming the alternate method and creating a library of hundreds of drinks that supports many ingredients User Interface Once the availability of cocktails is efficiently checked the menu of available cocktails is printed to the serial terminal The available drinks are displayed with the name and ingredients in each drink and by menu item number That number is bounds checked to ensure that it is less than the number of cocktails on the menu Bounds chec

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