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Development of a Proximity Based Alternative Input

1. 8 Picture 4 Circuit diagram to measure the distance voltage dependency Permanent shining Picture 5 Measurement setup to measure the dependency of object to sensor distance and voltage drop across the phototransistor permanent shining infrared LED pinboard sensor white paper on slide ce cece cece ER RR ee ee RR ee Re aa ek Re Re ee ed Re AR AAR ee nn 13 Picture 6 Measurement setup to measure the dependency of object to sensor distance and voltage drop across the phototransistor permanent shining infrared LED pinboard sensor white paper on slide guide rail pointer to stop at every MM ee RR AR AAR ee Re RR ee Re ee 13 Picture 7 Voltage drop across phototransistor depending on object to sensor distance under artificial light conditions three different series resistors R 2200 R2 1200 R3 91Q 14 Picture 8 Voltage drop across phototransistor depending on object to sensor distance under artificial light amp daylight conditions cloudy sky no direct sunlight three different series resistors R 2200 R3 1200 R3 910 ee ee Re ee RR ee ee ee ee ee ee ee ee ee ee ee 14 Picture 9 Voltage drop across phototransistor artificial light compared to artificial light amp daylight cloudy sky no direct sunlight series resistor R1 2200 ee ee ee ee ee 15 Picture 10 Circuit diagram to measure the distance voltage dependency pulsed LED including the parallel resonant circuit to transform
2. een 19 3 2 3 Calculating the Difference and the Average cccccccccecccecececeeeeeeeeeeeeeeeeneeereess 20 3 2 4 Communication Protocol and Features cccccceesseecceeeeeeeeeseeeeeeeeeeeeseeseseeeeeeeese 20 3 2 5 Communication of the Teensy USB Development Board Teensy 2 0 22 3 2 6 Overview of the Source Files c files and their Functions 24 3 3 Writing the ASTeRICS Plugin Code arena ae 26 33 1 Bundle Descriptor sis EE EE rar Ran engeren 27 3 3 2 Component Lifecycle ie ee ee ee ee 28 3 4 Design of the Printed Circuit Board PCB and the MountiING ese Re ee 29 4 RESUS ss EE EE GR eek Seg ee ee ee ee se Ae pa ee eae 32 5 DISCUSSION ANG CONCIUSION Se te DE Dee De de he se GE Se Be Re EE mune DE eds De de 37 Bibliography N 39 List of Pictures es ee ee ee ee ee ee ee ee ee nn List of Tabl S es 4 a le Re GEE A Source files c files of proximity sensor CIM 1 Introduction This thesis can be placed in the field of assistive technology for motor disabled persons More precisely the content of the paper belongs to the sub group of alternative input devices which replace a computer mouse or a switch in general Especially people who suffer from partially or complete motor impairments of all extremities tetraparesis paralysis are reliant on these alternative input devices in order to manage their daily routine or to use a computer In order to make lives of motor
3. 4k7 Picture 4 Circuit diagram to measure the distance voltage dependency Permanent shining LED Pointer to Picture 5 Measurement setup to measure the Picture 6 Measurement setup to measure the dependency of object to sensor distance and dependency of object to sensor distance and voltage drop across the phototransistor voltage drop across the phototransistor permanent shining infrared LED pinboard sensor permanent shining infrared LED pinboard sensor white paper on slide white paper on slide guide rail pointer to stop at every mm Drawing the diagrams of dependency of the object to sensor distance to the voltage drop across the phototransistor it has to be noticed that the part of the circuit containing the resistor Ry and the phototransistor works like a voltage divider This means that with little or no reflected infrared light reflecting object far away the phototransistor acts like an almost infinite big resistor as there exists no voltage potential between base and emitter and a current flow from collector to emitter is not possible Therefore all the supply voltage Vcc drops across the resistor Ry By reducing the distance between object and sensor the resistance of the phototransistor decreases as the voltage potential between base and emitter increases so that a current flow from collector to emitter is enabled Now the supply voltage Vcc drops across both parts Rw and the phototransistor of
4. Vop 5V the values for the different series resistors could be calculated using Formula 1 first Vop Ve Voltage applied on series resistor Vp Formula 1 Applied on the above listed values Vp 5V 1 7V 3 3V Secondly the value of the series resistor can be calculated by using a converted type of the Ohm s law UR Formula 2 Converted law U R I Formula 3 Now the above calculated voltage of 3 3V that has to be applied on the resistor in order not to exceed maximum Vr of the diode and the desired Ir can be inserted into Formula 3 Table 2 shows the calculation for the three different series resistors that are needed to generate the three values of lr Ri 20 165 220 15 R2 3 3 30 110 120 27 5 R 40 82 5 91 36 Table 2 Calculation of three different series resistors to gain three different values of Ir 20mA 30mA 40mA For the measurement itself the sensor and the corresponding series resistor were fixed on a pinboard circuit drawing see Picture 4 This pinboard was mounted on one end of a guide rail and a white paper on a slide was moved away from it Picture 5 and Picture 6 Every millimeter the slide was stopped and the current voltage value was measured with an oscilloscope Tektronix Four channel digital storage oscilloscope TDS 2024 The whole circuit was supplied with 5V from a power supply Manson Switching mode power supply NRP 3630 12 Vou
5. actuators o actuators execute the desired action and are driven directly or indirectly by data from sensors All the listed components have ports to connect to other components so that a data exchange between them can occur There exist four types of ports input output event listener and event trigger ports 4 Picture 1 Example of an ACS model consisting of a sensor FacetrackerLK tracks the position of the nose or the chin via a web cam a processor Averager stores a defined number of values that arrive at the input port averages them and sends the value via the output port and an actuator Mouse the mouse pointer movements in horizontal direction are now carried out via the horizontal movements of the user s nose 2 Materials 2 1 Reflective Object Sensor QRD1114 A reflective object sensor consists of an infrared light emitting diode LED and for sensing the reflected light a npn phototransistor that converts light into electric current Both LED and phototransistor are placed side by side on the top of the sensor The light that is measured with the phototransistor has to be reflected by an object in the near of the sensor The more infrared light is reflected by an object more voltage drops between base and emitter and therefore more current flows from collector to emitter Also the voltage drop across the phototransistor voltage drop across collector and emitter changes with the intensity of the reflected infrared li
6. gt met P us D4 DS Ds 0 er co Cl cs Os C5 C6 Cc7 ZIIILIZIIII III 46 VO Pins 8 Analog Inputs 9 PWM Ze Picture 3 Teensy 2 0 Development Board with header pins 7 2 3 Components of the AsTeRICS ACS model that is used with the Proximity Sensor In order to make the new proximity sensor usable as a mouse it was necessary to develop a new model within the ACS This model consists of several components that help to adjust the characteristics and the behavior of the proximity sensor In this section only the components itself and their functions are shortly described For the working principle of the whole model see Chapter 4 As source of information in this chapter the help function of the ACS was used Also look there for more detailed information about the different used components 2 3 1 Utilized Processors Averager This component consists of one input and one output port As its name already suggests it averages values that enter the component via the input port Therefor the user has the possibility to select the buffer size thus the number of values over which the average should be built In case of the proximity sensor four values first get filled in the buffer and then are averaged This helps to flatten the curve even more SampleAndHold The SampleAndHold component provides four input and output ports and one event listener port After capturing an event that was either sent by the AutostartEvent or the ButtonGr
7. void update_autoreplynum void autoreply_num if autoreply_num 0 autoreply_num 0x80 CIM_frame serial_number autoreply_num CIM_frame reply_code CMD_EVENT_REPLY void generate_ADCFrame uint16_t adcval CIM_frame cim_feature TEENSY_CIM_FEATURE_ADCREPORT CIM_frame data 0 uint8_t adcval amp Oxff CIM_frame data 1 uint8_t adcval gt gt 8 CIM_frame data_size 2 update_autoreplynum reply_DataFrame PORTD 1 lt lt 6 void generate_EventFrame int a CIM_frame cim_feature TEENSY_CIM_FEATURE_SEND_EVENT CIM_frame data 0 a CIM_frame data_size 1 update_autoreplynum reply_DataFrame PORTD 1 lt lt 6 define FRAME_DONE 99 Ivoid parse_CIM_protocol unsigned char actbyte 50 void parse_CIM_protocol void uint32_t checksum 0 static uint8_t transmission_mode static uint8_t reply status code static uint8_t last serial uint8_t actbyte while usb serial available IIPORTD 1 lt lt 6 actbyte usb_serial_getchar switch readstate case 0 first sync byte reply status code 0 if actbyte readstate break case 1 second sync byte if actbyte T readstate else readstate 0 break II packet in sync case 2 ARE ID SW version low byte ARE_frame are_id actbyte readstate break case 3 ARE ID SW version high byte ARE_frame are_id uint16_t actbyte lt lt 8 if ARE_frame are_id lt ARE_MINIMAL_VERSION loutda
8. 14 3 2 6 Overview of the Source Files c files and their Functions The firmware of the microcontroller consists of five source files Those five source files are ProximityCIM c Timer c Adc c CimProtocol c and usb_serial c In this chapter the function of each file is going to be shortly described A state machine diagram Picture 14 shall help to understand the program flow Timer c With this source file the pulsing of the infrared diode and the sampling rate of the sinus shaped signal are implemented The file contains a function that configures both of the timers On configuration relates to the compare match values that are written to the output compare registers OCR1A and OCRIB The counter counts from zero to this defined value Reaching the compare match value the corresponding interrupt service routine is carried out In case of reaching the value that was written to OCR1A 109 pulsing the diode see Chapter 3 2 1 the output compare pin OC1A equals pin PB5 on the printed circuit board gets toggled automatically This toggling is defined due to the register TCCR1A To make the start and stop command via the ARE ACS possible the compare match interrupts that correspond to the value written in OCR1B sampling frequency see Chapter 3 2 2 can be turned on off via the functions start timerl stop timer1 Furthermore the Timer c file contains the service routines ISRs that correspond to the output compare matches Each of the bo
9. 25 30 35 40 45 50 L ad Sensor to object distance mm g Picture 8 Voltage drop across phototransistor depending on object to sensor distance under artificial light amp daylight conditions cloudy sky no direct sunlight three different series resistors R z2200 R2 1200 R3 910 14 5 50 5 00 4 50 Voltage drop across phototransistor artificial light amp daylight series resistor R1 4 00 wis lVoltage drop across phototransistor artificial light series resistor R1 3 50 3 00 2 50 2 00 1 50 1 00 Voltage drog across phototransistor V 0 50 0 00 Sensor to object distance mm Picture 9 Voltage drop across phototransistor artificial light compared to artificial light amp daylight cloudy sky no direct sunlight series resistor R 2200 Comparing the graphs of the three different series resistors R R2 and R3 in Picture 7 it is apparent that the most sensitive area of R can be found within 5mm to 25mm Increasing the intensity of the emitted infrared light by using smaller series resistors R and R3 of the infrared diode the most sensitive area is shifted to distances within 7mm to 30mm Looking at Picture 8 opened sun blinds the comparison of the graphs of the three different series resistors R R2 and R3 achieves nearly the same result as in Picture 7 closed sun blinds While the most sensitive areas at short distances do not show a significant variation a noticeable differe
10. are used in case of the proximity sensor are Init Enable disable DOUBLECLICK RIGHTCLICK DRAGCLICK and saveCurve Picture 25 The button Init is pressed after positioning the sensor correctly at the chin The value that is now sent from the proximity sensor thus the current position and the corresponding light reflection is initialized as neutral point Clicking the button Enable disable enables or disables the mouse function of the proximity sensor If the function is disabled the normal mouse can be used Enabling the proximity sensor mouse function means that the normal mouse cannot be used The buttons that are written in capital letters provide the choice between the different clicking possibilities for the next left click saveCurve is used to save the curve that was formed in the component AdjustmentCurve Timer This component has one input one output one event trigger and one event listener port It can measure time in milliseconds This measured time can either be reported on the output port or after defining a time period events can be triggered when the time period has passed Used with the proximity sensor only the event listener port waits for 10 events that are sent from the Deadzone component and the event trigger port sends events to PathSelector and WavefilePlayer component are used Both Timer components start to count after the user enters the defined dead zone T
11. called Proximity SONS Oleic EE EE weeds Melee ets Dees wavs Se EE Se ebay teres et ceed ED RE eee seeded 21 Table 5 Parts of the printed circuit board 20 2 ccc ees esse ee ee Re ee ee ee ee ee ee ee ee ee 30 Table 6 Performance data of the proximity sensor used with an on screen keyboard 1 and 10 time usage compared to the performance data of a single push button with an on screen keyboard and a Scanning method s44444440nnsnnnnnnnnnnnnnnenn en Re ee ee ee ee ke ee Re 36 Table 7 Time that is needed to search and download a file on the Internet One time the proximity sensor was used the other time a one switch mouse uesesesenensssnsnennnenenenen nenn 36 43 A Source files c files of proximity sensor CIM ProximityCIM c is AsTeRICS Proximity CIM Firmware using Teensy 2 0 Controller board file ProximityCIM c Version 0 1 Authors Chris Veigl FHTW Franziska Horak Date 30 04 2013 I include lt avr io h gt include lt avr pgmspace h gt include lt stdint h gt include lt util delay h gt include lt inttypes h gt include lt avr interrupt h gt include lt stdlib h gt include lt inttypes h gt include lt stdio h gt include lt string h gt include lt util delay h gt include Adc h include Timer h include CimProtocol h include usb_serial h define CPU_PRESCALE n CLKPR 0x80 CLKPR n define AUTOUPDATE_VALUES 0 define THRESHOLD_BELOW_ABO
12. canonical_name eu asterics component sensor proximity ProximityInstance gt lt type subtype Sensor Modules gt sensor lt type gt singleton gt false lt singleton gt lt description gt Distance Sensor lt description gt Type name description and data type of the input and output port lt ports gt lt outputPort id distance gt lt description gt Output port of proximitysensor lt description gt lt dataType gt integer lt dataType gt lt outputPort gt lt inputPort id input gt lt description gt Input port of proximitysensor to set threshold lt description gt lt mustBeConnected gt false lt mustBeConnected gt lt dataType gt integer lt dataType gt lt inputPort gt lt ports gt The output port distance delivers if sending mode 0 see Table 4 Picture 14 has been chosen permanently the average of always eight diff values see Chapter 3 2 3 The input port input is used to set the threshold to produce events For that sending mode 1 2 or 3 see Table 4 Picture 14 has to be chosen 27 Type name and description of the event trigger ports lt events gt lt eventTriggererPort id LowToHigh gt lt description gt etp current value exceeds threshold sending 1 lt description gt lt eventTriggererPort gt lt eventTriggererPort id HighToLow gt lt description gt etp current value falls below threshold sending lt description gt lt eventTriggererPort gt lt events gt
13. disabled persons more comfortable there already exists a variety of systems for alternative human computer interactions The wide range of those systems reaches from eye or face tracking systems which can be used with on screen keyboards to voice input and special mice or keyboards 1 As tetraparesis paralysis as well as motor disabilities in general can differ in appearance and severity it is important that the adjustment of alternative input devices can be done easily and individually to satisfy the users needs as good as possible The project AsTeRICS Assistive Technology Rapid Integration amp Construction Set 2 has exactly the goal to meet those before mentioned demands This paper is another contribution to the AsTeRICS project as it describes the development of an alternative input device that can be used with the AsTeRICS software The new device is going to be built out of a sensor that emits infrared light via an infrared diode and measures the infrared light that is reflected by an object via a phototransistor Depending on the distance between sensor and object the measured voltage drop across collector and emitter changes 3 In the context of the application and the project AsTeRICS the sensor is going to be called proximity sensor The reflecting object is going to be the chin of the user so that by moving the jaw the amount of reflected light and therefore the amount of the measured voltage changes The voltage then serves
14. received square wave signal into a sinus shaped signal and to raise the operating point to 2 5V inserted 33kQ resistors Vin delivers the frequency of 10kHz to pulse the diode Capacitor C 10nF is used to filter the signal before it enters the microcontroller via Vou VoCHOV ccccccseeseccccecesceeseseeceeceeecesseesuseaeeeeeesesenes 16 Picture 11 Square wave signal of the pulsed infrared diode with a frequency of 10kHz and the corresponding sinus shaped signal that is produced by the parallel resonant circuit that follows the phototransistor with the points of measurement ee ee RR Re RR ee Re RR ee Re ee 17 Picture 12 Measurement setup to measure the dependency of object to sensor distance and voltage drop across the phototransistor pulsed infrared LED connections to pinboard sensor fixed on the steady part of the sliding caliper white paper fixed on the movable part of the sliding caliperF iS GEE Ee ee ee ee Ke Rd EG de n Ge ee ee ee se en ee ee e Be De dee ek ee ei 17 Picture 13 Voltage drop across phototransistor depending on object to sensor distance pulsed infrared LED green graph Delta Maximum Minimum ee ee ee ee ee ee ee ee 18 Picture 14 Schematic drawing of the program flow State Init contains the blinking LED and the customization of the ADC trigger source If the new arrived packet does not contain the identifier T the packet is faulty and the waiting for a new packet starts again After recogni
15. statt Um die neue Eingabehilfe mit der ARE und der ACS AsTeRICS Configuration Suite erm glicht einfaches Erstellen eines Modells welches die Werte die der neue Distanzsensor liefert zu Mauszeigerbewegungen umwandelt verwenden zu k nnen musste die entsprechende Software geschrieben werden Mit der daraus resultierenden neuen alternativen Eingabehilfe wurde eine weitere M glichkeit geschaffen Personen mit starken physischen Einschr nkungen den Zugang zu Bildung und Wissen aber auch zur Teilnahme am sozialen Leben zu erleichtern Schlagw rter Assistierende Technologie Alternatives Eingabeger t Reflektierte Infrarotstrahlung messender Sensor Teensytt Development Board EU Projekt AsTeRICS Abstract This work describes the development of a new alternative input device for people with physical limitations The development was part of the project AsTeRICS Assistive Technology Rapid Integration amp Construction Set of the EU Aim of this project is an easier access to PCs or cell phones for people who suffer from a Tetra or Paraplegia of the upper extremities This is achieved due to a construction set that consists of several input devices and a software platform For the development of the new input device a reflective object sensor that emits infrared light by an infrared diode and detects the light that is reflected by an object with a phototransistor was used To determine the possible operating range of the sensor severa
16. the voltage divider Hence the measured voltage across Ry decreases To be able to draw the dependency between the object to sensor distance and the voltage drop across the phototransistor it is needed to subtract the voltage values that were measured across Ry from Vcc 13 5 50 5 00 ET TEE Voltage drop across phototransistor artificiallight series resistor R2 4 50 gt Voltage drop across phototransistor artificial light 5 4 00 series resistor R3 g Nn 3 50 ee Voltage drop across phototransistor artificiallight Z series resistor R1 2 3 00 Qa 2 50 1 Oo 8 S 2 00 2 2 1 50 g s 1 00 0 50 0 00 T 0 5 10 15 20 25 30 35 40 45 50 Sensor to object distance mm Picture 7 Voltage drop across phototransistor depending on object to sensor distance under artificial light conditions three different series resistors R 2200 R2 1200 R3 91Q 5 50 5 00 Voltage drop across phototransistor artificial light amp daylight series resistor R1 4 50 S Ze Voltage drop across phototransistor artificial 4 00 light amp daylight series resistor R2 3 50 BR Voltage drop across phototransistor artificial o light amp daylight series resistor R3 3 3 00 2 a 2 50 gt a fe S 2 00 gt S 5 150 7 amp 1 00 gt 0 50 0 00 T T z T u T T T ERG T 0 5 10 15 20
17. thin ground wire has not to be in the shrinking hose The connection between PCB and sensor s was planned with a 4 way header However as the mounting wire is fixed permanently on the PCB and a shrinking 29 hose holds the mounting wire and the signal wires of the sensor together permanently a plug makes no sense any more Therefore the signal wires of the sensor are soldered directly onto the PCB 9 g LEISTE_GND PIN HEADER Socket 1 Row 20 LEISTE_VCC Contacts 2 54mm 2 10nF C1 C2 Capacitor SMT Package 0805 1 10uF C5 Capacitor SMT Package 0805 1 1KO R7 Resistor SMT Package 0805 2 2200 R3 R4 Resistor SMT Package 0805 2 22nF C3 C4 Capacitor SMT Package 1206 Replaced by normal sized components 4 33KQ R1 R2 R5 R6 Resistor SMT Package 0805 AWAY HEADER 1 TE Connectivity AMP Header 90 4 z g 4WAY_HEADER_2 Contacts 2 DIET MM Lumberg 1503 03 Socket 3 5mm Jack STEREO 3 5MM 2 2 10mH L1 L2 Multicomp Fixed Inductor Tolerance 5 Table 5 Parts of the printed circuit board As up to now only one sensor is used this sensor is connected to the holes of the 4WAY_HEADER_1 Picture 15 Picture 18 Leiterplatte 1 Horak Picture 15 PCB Layout for the proximity sensor 30 oo0oo000 T E ki TIHI Inductors Stereo jack iF Smm Picture 16 Unpopulated PCB Top Layer Picture 17 Populated PCB Top ine One end of the m
18. updates in ISR static volatile int16_t buffer BUFSIZE static int16_t sum 0 static uint8_t buffer_pos 0 measure_top 1 void ADC_Init void ADC_updates 0 ADCSRA 1 lt lt ADIF ADCSRB 0 ADMUX 0 sum 0 buffer_pos 0 measure_top 1 for int i 0 i lt BUFSIZE i bufferfi 0 ADCSRA 1 lt lt 5 1 lt lt 3 ADC Auto Trigger enable ADC Interrupt enable ADCSRA 1 lt lt 2 1 lt lt 1 ADC Prescaler 64 gt 250kHz ADCSRB 1 lt lt 2 1 lt lt 0 1 lt lt 7 Trigger Source Timer Counter1 Compare Match B High Speed Mode ADMUX 1 lt lt 6 1 lt lt 0 1 lt lt 1 VCC with external capacitor on AREF pin Single Ended Input ADC3 DIDRO 1 lt lt 3 Digital Input Disabled ADCSRA 1 lt lt 7 ADC enable gt in Auto Trigger Mode lithe first conversion is started a on a positive edge of the trigger signal periodische ADC Messungen gt ber Compare Match ISR OCR1B getriggert ISR ADC_vect static int16_t berg unsigned char low high low ADCL high ADCH uint16_t diff 0 46 if measure top berg uint16_t high lt lt 8 low 1ste Messung Bergwert messen measure_top 0 else diff berg uint16_t high lt lt 8 low 2 Messung Differenz bilden gt diff berg Talwert sum sum buffer buffer_pos buffer buffer_pos diff sum diff if I buffer_pos buffer post1 BUFSIZE buffer filled with
19. using the scanning methods combined with a push button and when using the proximity sensor the latter has the huge advantage that not only the keyboard can be used but all normal mouse functions can be carried out as well Comparing the mouse functions of the proximity sensor with those provided by a one switch mouse one can see that the time that is needed to open a homepage and to download a file can be reduced by about 50 37 Another improvement can be brought about due to the possibility of connecting a second sensor to the PCB This can be done easily as the circuit that is needed for one sensor was placed a second time on the PCB By adding a second sensor and implementing some changes in the CIM s firmware and the ARE software it is possible to generate horizontal and vertical mouse pointer movements separately For that reason one sensor stays beside the chin the position that is also used now and the other one is fixed beneath the chin Due to this further development it is no longer necessary to move the mouse pointer first to the desired horizontal vertical position changing the direction of the mouse pointer movement to vertical horizontal and then move the mouse pointer to the desired vertical horizontal position With the usage of two sensors the mouse pointer can be moved directly without spending time on the change of direction to the desired position 38 Bibliography 1 AsTeRICS Deliverable D24 Report on the stat
20. value that was either saved after the AutostartEvent component sends an event or after the Init button of the button grid is pressed gets subtracted from the current values This makes a calibration of the neutral point of the chin possible To make the sensor as intuitively as possible the result of the subtraction has to be multiplied by 1 in order to produce a mouse pointer movement to the left when the chin is moved to the left After the calibration the AdjustmentCurve component enables the user to adjust the curve that is formed by his her chin movement This can be necessary to compensate the fact that the movement of the chin away from the sensor causes less acceleration as the movement closer to the sensor Furthermore the dead zone resting zone can be made broader or narrower Now the signal that leaves the AdjustmentCurve component is ready to be used as mouse pointer movement or action clicking signal After choosing the action right click left click drag click for the next mouse click that should be performed over the buttons on the ButtonGrid component the StringDispatcher component sends the according command to the input action of the Mouse component After entering the defined dead zone radius an event is sent from the Deadzone component and both Timer components Timer 1 and Timer 1 1 start to count the time in milliseconds that passes by Timer 1 is used to change the direction of the mouse pointer movement from
21. 22 Box containing the PCB fixed on the dedicated head mounting 32 Picture 23 Sensor mounted on the head 24242424440000000000nnnenn nenne nnnnnnnnrnnernn nn 32 Picture 24 AsTeRICS ACS model for mouse control ee ee ee ee 34 Picture 25 Graphical user interface oft he ASC model for mouse control see 34 Picture 26 Sensor mounted on the head chin in neutral position u2uus0ss0ensnnenennnnn 35 Picture 27 Sensor mounted on the head chin moved to the left closer to the sensor 35 Picture 28 Sensor mounted on the head chin moved to the right away from the sensor 35 Picture 29 Screen shot of the use case Searching and downloading a file from a homepage On the right side of the screen the graphical user interface is illustrated At the bottom one can see the OSKA on screen keyboard and at the top the browser window was 42 List of Tables Table 1 Key features and specifications of the Teensy 2 0 Development Board 7 8 Table 2 Calculation of three different series resistors to gain three different values of Ir CZ OTIS OMAR IVY ee hea ae naa EL De ER LE ee ee Tee 12 Table 3 CIM protocol structure packet format Italic descriptions refer to communication from CIM to ARE 5 see also for more detailed descriptions of packet data fields 21 Table 4 List and description of the CIM features that are provided by the new developed CIM
22. 9us As the output pin should be toggled twice within those 109us it is necessary to divide the periodic time by two The half of the periodic time therefore is 54 5us Dividing the half of the periodic time by the time of one timer tick 0 5us leads to 109 timer ticks which equal the reload value The compare value now can be written to the output compare register OCR1A 9 If now the value of Timer Counter1 in register TCNT1 equals the compare value in OCR1A a 18 compare match A interrupt is triggered and the output compare pin OC1A is toggled automatically special function of pin PB5 adjusted in register TCCR1A Bit COM1A 1 9 every 54 5us Because of the toggling the infrared LED of the sensor is either turned on or turned off The interrupt service routine ISR TIMER1 COMPA vect that gets called every time a compare match A interrupt occurs contains only one line where the compare value is increased by 109 Otherwise Counter1 would first count to 2 and again to 109 to trigger an new interrupt so that a signal with another frequency than 9 174kHz would be generated 3 2 2 Measuring Maxima and Minima Triggering the ADC The configuration of the analog to digital converter ADC contains the following parts First the ADC prescaler that is defined with 64 register ADCSRA 12 Bits ADPS0 1 2 Dividing the system clock frequency of 16MHz by 64 leads to an ADC clock frequency of 250kHz and a periodic time of Aus Secondly the so
23. ALID_FEATURE if status code amp CIM_ERROR_INVALID_FEATURE invalid data size or feature Il LEDs_ToggleLEDs LED5 indicate wrong feature Il UART_Print invalid data size or no feature if ack needed reply_Acknowledge return 1 49 void reply Featurelist void if UEINTX amp 1 lt lt RWAL wenn Buffer nicht voll ist CIM_frame reply_code CIM_ERROR_CIM_NOT_READY lt lt 8 if UEINTX amp 1 lt lt RWAL wenn Buffer voll ist CIM_frame data_size sizeof TEENSY_CIM_FEATURELIST feature list length usb_serial_write uint8_t amp CIM_frame CIM_HEADER_LEN usb_serial_write uint8_t amp TEENSY_CIM_FEATURELIST CIM_frame data_size void reply_UniqueNumber void CIM_frame data_size 4 lenght of unique number usb_serial_write uint8_t amp CIM_frame CIM HEADER LEN usb_serial_write uint8_t amp TEENSY_CIM_UNIQUE_NUMBER CIM_frame data_size void reply_Acknowledge void if UEINTX amp 1 lt lt RWAL wenn Buffer nicht voll ist CIM_frame reply_code CIM ERROR CIM NOT READY 8 if UEINTX amp 1 lt lt RWAL wenn Buffer voll ist CIM_frame data_size 0 no data in ack frame usb_serial_write uint8_t amp CIM_frame CIM_HEADER_LEN void reply_DataFrame void usb_serial_write uint8_t amp CIM_frame CIM_HEADER_LEN usb_serial_write uint8_t CIM_frame data CIM_frame data_size
24. D CIM ID 2 version CIM gt ARE CIM ID identification of CIM type Commands answers from CIM can contain optional data e g ADC values Data size Data size 2 0x0000 0x0g00 P says how many data is attached to the command answer A 0x00 0x7f 0x80 Serial packet Helps to identify what reply of the CIM belongs 1 Oxff for event number to which request from the ARE replies from CIM CIM Feat Er 2 Definition of addressed CIM feature address Request LSB represents a command code that is Code 2 globally valid for all CIM types Reply Code MSB 20 ARE 2 CIM specification of tansmission mode CIM gt ARE error status code related to transmission Additional data of a packet Actual length Optional dat 0 2048 ptional data given Data size field Optional CRC 6 apa CRC32 checksum checksum Table 3 CIM protocol structure packet format Italic descriptions refer to communication from CIM to ARE 5 see also for more detailed descriptions of packet data fields Generally speaking the programming of the CIM protocol can be categorized into two different parts 1 The first part to be shortly described here is the analysis of a new arriving packet that was sent from the ARE to the CIM After recognizing the two synchronization bytes and T one after the other the parsing of the packet goes on Now variables are filled up with the right byte accord
25. Development of a Proximity Based Alternative Input Device for Motor Disabled Persons Term paper submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Engineering at the University of Applied Sciences Technikum Wien Degree Program BBE By Franziska Horak Student Number 1010227029 Supervisor 1 Dipl Ing Christoph Veigl Vienna 13 05 2013 FACHHOCHSCHULE TECHNIKUM WIEN Declaration confirm that this paper is entirely my own work All sources and quotations have been fully acknowledged in the appropriate places with adequate footnotes and citations Quotations have been properly acknowledged and marked with appropriate punctuation The works consulted are listed in the bibliography This paper has not been submitted to another examination panel in the same or a similar form and has not been published declare that the present paper is identical to the version uploaded Vienna 13 05 2013 Franziska Horak Kurzfassung In dieser Arbeit soll die Entwicklung eines neuen alternativen Eingabeger tes f r Personen mit physischen Einschr nkungen beschrieben werden Die Entwicklung fand im Rahmen des EU Projektes AsTeRICS Assistive Technology Rapid Integration amp Construction Set statt Ziel dieses Projektes ist es durch ein Konstruktionsset f r assistierende Technologien welches aus verschiedenen Eingabehilfen und einer Softwareplattform besteht den Zugang zu PC od
26. SB Implementers Forum Inc 12 it is easy to see from the usb_serial c file that comes with the 22 Teensy Development Board that the Teensy Board conforms to the Communication Device Class CDC specifications DeviceClass 2 DeviceSubClass 0 DeviceProtocol 0 Configuration Descriptor The configuration descriptor contains information about a specific device configuration and the number of interfaces that are provided by this configuration Reguesting the configuration descriptor all related interface and endpoint descriptors are returned to the host Different to the device descriptor an USB device can have one or more configuration descriptors Each of the configurations that are defined by the configuration descriptor has one or more interfaces and the corresponding descriptors and each interface has optional endpoints and their according descriptors The configuration descriptor contains information about the length of the descriptor itself the type of the descriptor constant that belongs to the configuration descriptor 02h the number of interfaces that are supported by this configuration a description of the configuration string descriptor and the maximum power consumption of the USB device in a specific configuration power comes from the bus USB device is fully operational For more detailed configuration options see 11 p 264 266 Table 9 10 Comparing the above mentioned information with th
27. The event triggerer ports LowToHigh and HighToLow are used when a threshold is set and the current value exceeds or succeeds the threshold Name data type default value and description of the properties lt properties gt lt property name threshold type integer value 8 description Value to produce events gt lt property name sendingflode type integer value 8 combobox Continous data Events below gt above Events above gt below Events both description sending mode of the proximity sensor gt lt properties gt 3 3 2 Component Lifecycle Within the component lifecycle the actual component proximity sensor is implemented The lifecycle can generally divided into two sections 5 the lifecycle support methods and the component support methods The lifecycle support methods are used to handle events that are related to the component lifecycle There exist four different states a component can be in 5 Ready If a component is in the state Ready it is stateless By starting the component becomes Active Active The state Active is stateful From this state the component can either become Paused or Stopped Paused If the component is Paused stateful it can either be activated again or completely stopped Stopped Stopping the component means that it becomes stateless again The component support methods are used to access the input and output po
28. VE 1 define THRESHOLD_ABOVE_BELOW 2 define THRESHOLD_BOTH 3 extern struct CIM_frame_t CIM_frame uint16_t oldVal void setupHardware void Timer_Init ADC_Init DDRD 1 lt lt 5 PORTD amp 1 lt lt 5 DDRD 1 lt lt 6 PORTD amp 1 lt lt 6 DDRB 1 lt lt 5 PORTB amp 1 lt lt 5 PB5 bzw OC1A gt Output init low DDRB amp 1 lt lt 0 PORTB 1 lt lt 0 PBO input with pullup Il start_timer1 int main void uint16_t value CPU_PRESCALE 0 Il initialize the USB and then wait for the host to set configuration If the Teensy is powered Il without a PC connected to the USB port this will wait forever usb_init while usb_configured wait _delay_ms 1000 setupHardware init_CIM_frame seil while 1 parse_CIM_protocol look if new command arrived from ARE and process it if ADC updates lisa new buffer of ADC values available updated via the ADC ISR value mittl_berechnen calculate averaged value ADC_updates 0 switch selection case AUTOUPDATE_VALUES generate_ADCFrame value break case THRESHOLD_BELOW_ABOVE if oldVal lt threshold amp amp value gt threshold generate_EventFrame 1 break case THRESHOLD_ABOVE_BELOW if oldVal gt threshold amp amp value lt threshold generate_EventFrame 0 break case THRESHOLD_BOTH if oldVal lt threshold amp amp value g
29. _REQUEST_START_CIM if data_size 0 cli init_CIM_frame setupHardware start_timer1 seil else status code CIM ERROR INVALID FEATURE break 48 case CMD REOGUEST STOP CIM if data_size 0 first_packet 1 reset first frame indicator etc stop_timer1 else status code CIM_ERROR_INVALID_FEATURE break case CMD_REQUEST_READ_FEATURE read feature from CIM switch ARE_frame cim_feature case TEENSY_CIM_FEATURE_UNIQUENUMBER read unique serial number if data_size 0 reply_UniqueNumber ack_needed 0 else status code CIM_ERROR_INVALID_FEATURE break default not a valid read feature status_code CIM_ERROR_INVALID_FEATURE break case CMD_REQUEST_WRITE_FEATURE write feature to CIM switch ARE_frame cim_feature which feature address case TEENSY_CIM_FEATURE_MODE_SELECTION if data_size 2 cli selection uint16 HARE frame dataf0 selection uint16_t ARE_frame data 1 lt lt 8 sei break case TEENSY_CIM_FEATURE_SET_THRESHOLD if data_size 2 cli threshold uint16_t ARE_frame data 0 threshold uint16_t ARE_frame data 1 lt lt 8 sei break case TEENSY_CIM_FEATURE_SET_ADCPERIOD if data_size 2 cli ADC_updatetime uint16_t ARE_frame data 0 ADC_updatetime uint16_t ARE_frame data 1 lt lt 8 seil break default not a valid write feature status_code CIM_ERROR_INV
30. as input signal for the Analog to Digital converter ADC of an ATMEL 8 bit AVR microcontroller AT90USB1286 that is mounted on a Teensy USB Development Board Teensy 2 0 The signal afterwards gets processed within the microcontroller in terms of averaging the measured values to achieve better results Following this the averaged values are sent to the AsTeRICS Embedded Computing Platform Reaching the Embedded Computing Platform it is easily possible for the end user to combine the sensor with a variety of already implemented actuators e g on screen keyboards sensors and processors These combinations are called models that are built in the AsTeRICS configuration suite ACS One model is going to be used for mouse movements There is going to be the design of a printed circuit board PCB that contains the necessary circuits between sensor and ADC and of a fixation so that the sensor can be mounted at the right position near the chin For the fixation an advanced head mounting that was already designed during the project AsTeRICS with an appertaining box that is going to contain the PCB is used At the end of this paper a new fully working and usable sensor shall be presented 1 1 Background As already mentioned in the introduction Chapter 1 the new developed alternative communication device proximity sensor is going to be part of the project AsTeRICS Assistive Technology Rapid Integration amp Construction Set The project s a
31. dar ber steigt 0x04 0x00 Activate periodic ADC Reports data 2 bytes period in milliseconds 0 off 0x05 0x00 ADC value report berechneter Mittelwert data 2 bytes Mittelwert wird standig gesendet struct ARE_frame_t ARE_frame struct CIM_frame_t CIM_frame unsigned char readstate 0 unsigned int datapos 0 uint8_t first_packet 1 volatile uint16_t threshold 200 volatile uint16_t selection 0 uint16_t ADC_updatetime 0 void setupHardware void init_CIM_frame void CIM_frame packet_id CIM_FRAME_START T Packet ID sync bytes CIM_frame cim_id CIM_ID_TEENSY uint8_t process_ARE_frame uint8_t status_code uint tack needed uint t data_size 0 uint8_t command command uint8_t ARE_frame request_code CIM_frame cim_feature ARE_frame cim_feature CIM_frame serial_number ARE_frame serial_number CIM_frame reply_code uint16_t status_code lt lt 8 command data_size uint8_t ARE_frame data_size ack_needed 1 if status_code amp CIM_ERROR_INVALID_ARE_VERSION 0 II UART_Print feature UART_Putchar command Il no serious packet error switch command process requested command case CMD_REQUEST_FEATURELIST if data_size 0 reply_FeatureList reply requested feature list ack_needed 0 else status code CIM_ERROR_INVALID_FEATURE break case CMD_REQUEST_RESET_CIM if data_size 0 status_code CIM_ERROR_INVALID_FEATURE break case CMD
32. e CIM communication as is parses the packets that are sent from the CIM to the ARE public void handlePacketError CIMEvent e If a packet that was sent from the CIM to the ARE is incorrect or an answer is missing at all this method is used to handle the problem 3 4 Design of the Printed Circuit Board PCB and the Mounting Designing the PCB the free version of the CadSoft EAGLE PCB Design Software was used The size of the circuit board was given by a mounting that can be placed on the head that already exists This mounting includes a box where a circuit board is placed and protected against damage On the PCB the circuit that is shown in Picture 10 was placed twice so that there exists the possibility to connect a second proximity sensor to the board to realize a control with directly selectable x and y coordinates Further it was important to be able to fix the Teensy Development Board easily on the PCB Therefore two rows of sockets were placed so that the Teensy Board can be plugged in without any effort Also a 3 5mm stereo jack connector that is used as mono jack connector was added and connected to a digital in pin ofthe Teensy Board in order to connect it with for example a simple switch button To facilitate an easy adjustment of the sensor at the chin a pliable mounting wire was used For the fixation of this wire a plane that is connected to ground is provided Connecting the mounting wire with ground has the advantage that the
33. e answer packet implemented in CimProtocol c according to the selected sending mode after the buffer of the Adc c file that contains the diff values is filled and the average was calculated If one of the sending modes was chosen the comparison of the current value with the threshold is also carried out in the ProximityCIM c file Picture 14 Schematic drawing of the program flow State Init contains the blinking LED and the customization of the ADC trigger source If the new arrived packet does not contain the identifier T the packet is faulty and the waiting for a new packet starts again After recognizing a commando out of a right packet the commando gets processed and an answer packet is replied If the commando that is read out of the packet is Start the trigger source of the ADC is started and therefore the sampling and all further steps are started too Sending the command Stop means that the trigger source of the ADC is turned off so that no sampling takes place anymore 3 3 Writing the AsTeRICS Plugin Code Using the AsTeRICS Plugin Creation Tools creates the base frame of a new plugin here proximity The Plugin Creation Tools provide the necessary folder structure the bundle descriptor and a template for the JAVA source code Main part of the Plugin Creation Tools is the Plugin Creation Wizard which creates the folders and files that are needed for the Eclipse build flow Those files also include alr
34. e can be developed another diagram of the dependency of the object to sensor distance to the voltage drop across the phototransistor Vac R 33k Picture 10 Circuit diagram to measure the distance voltage dependency pulsed LED including the parallel resonant circuit to transform received square wave signal into a sinus shaped signal and to raise the operating point to 2 5V inserted 33kQ resistors Vin delivers the frequency of 10kHz to pulse the diode Capacitor C 10nF is used to filter the signal before it enters the microcontroller via Vout Vcc 5V 16 5V square wave signal 10KHz OV t sinus shaped signal 10kHz 2 5V t points of measurement Picture 11 Square wave signal of the pulsed infrared diode with a frequency of 10kHz and the corresponding sinus shaped signal that is produced by the parallel resonant circuit that follows the phototransistor with the points of measurement Before the measurements which were needed to generate the diagram of the dependency of the object to sensor distance to the voltage drop across the phototransistor could be carried out another adjustment had to be done As the used electronic components of the parallel resonant circuit have tolerances of 410 the signal frequency fr is not exactly 10kHz By empirically adjusting the frequency the resonance frequency of the real parallel resonant circuit TR rea equals 9 174kKHz The measurements wer
35. e carried out with a similar measurement setup as it was used with the permanent shining infrared LED Chapter 3 1 1 Picture 12 shows the measurement setup The sensor which was connected to the whole circuit on the pinboard was fixed on the stationary part of a sliding caliper whereas the paper was fixed on the movable part The paper was moved away from the sensor stopped every millimeter and the current voltage values maximum minimum delta between maximum and minimum were measured with an oscilloscope This measurement setup leads to the diagrams of the dependency of the object to sensor distance to the voltage drop across the phototransistor shown in Picture 13 Picture 12 Measurement setup to measure the dependency of object to sensor distance and voltage drop across the phototransistor pulsed infrared LED connections to pinboard sensor fixed on the steady part of the sliding caliper white paper fixed on the movable part of the sliding caliper 17 Voltage drop across phototransistor Minima Voltage drop across phototransistor Maxima Voltage drop across phototransistor Delta Voltage drop across phototransistor V 0 5 10 15 20 25 30 35 40 45 50 55 60 Sensor to object distance mm Picture 13 Voltage drop across phototransistor depending on object to sensor distance pulsed infrared LED green graph Delta Maximum Minimum As it can be seen from the blue and the red graph in Picture 13 the sinus sha
36. e of the art 2 uo http www asterics eu index php id 2 Downloads gt Deliverables Date of last visit 24 4 2013 p 14 37 54 Contact details Kompetenznetzwerk KI I Projekt AsTeRICS AltenbergerstraRe 69 4040 Linz Austria Tel 43 732 2468 3770 AsTeRICS Homepage http www asterics eu index php id 2 Date of last visit 24 4 2013 Contact details see 1 3 Datasheet of Reflective Object Sensor QRD1114 p 2 4 AsTeRICS User Manual Verison 2 0 http www asterics eu index php id 2 Downloads gt Manuals Date of last visit 24 4 2013 p 5f 14 15 Contact details see 1 5 AsTeRICS Developer Manual Version 2 0 http www asterics eu index php id 2 6 7 I Downloads gt Manuals Date of last visit 24 4 2013 p 8f 50 53 17f 25f 29 Contact details see 1 http www pjrc com store teensypp html Date of last visit 29 4 2013 Contact details PJRC COM LLC 14723 SW Brooke CT Sherwood OR 97140 USA Tel 503 625 9328 email paul pijrc com technical questions robin pjrc com financial administrative questions http www pjrc com teensy Date of last visit 29 4 2013 Contact details see 6 8 U Tietze Ch Schenk Halbleiter Schaltungstechnik 12 Auflage Springer Erlangen und Munchen 2002 p 1544 39 9 Datasheet of ATMEL 8 bit AVR microcontroller AT90USB1286 p 117 142 145 138 140 326 331 318 10 J Axelson USB 2 0 Handbuch
37. e usb serial c file of the Teensy Development Board one can see that it supports two interfaces a maximum power consumption of 100mA but no string descriptor that describes the configuration Interface Descriptor The interface descriptor describes the interface that is used within a specific configuration and is therefore always returned as part of the configuration descriptor This descriptor provides information about the length of the descriptor itself the type of the descriptor anumber to identify the interface the total number of supported endpoints endpoint 0 is not included in the number of endpoints the functionality of the device similar to the device class configured by three bytes InteraceClass InterfaceSubClass and InterfaceProtocol For more detailed configuration options see 11 p 267 269 Table 9 12 In case of the proximity sensor there exist two interface descriptors and three endpoint descriptors One interface descriptor defines the device as communication device communication device class CDC and the other descriptor tells the host that the device can also operate as data interface belonging to the CDC 10 All the other descriptors that are found in the usb serial c file namely CDC Header Functional Descriptor Call Management Functional Descriptor Abstract Control Management Functional Descriptor and Union Functional Descriptor are not explained at this point For information about tho
38. eady a JAVA source code skeleton and the bundle descriptor of the plugin Within the Plugin Creation Wizard the type input output event listener event trigger the number and the appropriate data type of desired ports and 26 the properties of the new plugin can be created easily Properties can include for example a threshold that can be set by the user in the ACS 5 For creating a new plugin several ARE coding guidelines have to be considered These guidelines are listed in 5 Chapter 4 1 and therefore the explanation in this paper is going to be rather short Basically the names of plugins ports and properties should be intuitively and suitable for the purpose they are going to serve Variables in the plugin code should not be named differently to the names they were given in the bundle descriptor For naming conventions of ports and properties and plugin activation in the ACS and the ARE see 5 Chapters 4 1 and 3 2 3 3 1 Bundle Descriptor The bundle descriptor can be seen as an abstraction layer between the developer and the user who creates models out of different plugins in the ACS Further it describes the content of an individual bundle by providing information about the included components in this case the proximity sensor is the only component their ports and properties 5 The proximity sensors bundle descriptor consists of General information about the component lt componentType id asterics Proximity
39. ective object sensor consisting of an infrared diode and a phototransistor to measure the distance between the user s chin and the sensor provides easier computer access also for people who suffer from a Tetraplegia and therefore are only able to move their head Furthermore after the calibration process that includes the correct placement of the sensor on the mounting wire at the chin no strength is needed to operate the sensor It is also important to mention that also small and very exact mouse pointer movements are possible as the chin can be moved very precisely and the corresponding curve of the chin movement can be adjusted individually Due to the pulsing of the infrared diode a minimization of the influence that is caused by the ambient lights amount of infrared light was achieved However the ambient light s influence is not completely blinded out This could be caused by the reason that due to the amount of infrared light that is present in the ambient light the amplitude of the square wave signal and the therefore the amplitude of the sinus shaped signal get higher To counteract this circumstance the ACS models for mouse control and pinball include the AdjustmentCurve component This component makes it possible to define the zero point neutral position of the chin every time the proximity sensor is started or after a change of the lighting conditions With the mouse model the user is able to control the mouse pointer movement in horiz
40. er second fsampie gt 00HZ Tsampie 2ms would be sufficient as well Dividing Tsampie by the 54 5us the obtained number of 36 69 delivers the information that every 36 69 maximum minimum would have to be sampled to achieve a sample rate of 500Hz To sample alternately one maximum and one minimum it has to be an odd number of maxima minima that are skipped Setting the number to 39 and multiplying it with 54 5us we get a new periodic time of the sample rate T sample new 2 1255MS fsample new 470 47HZ Dividing Tsampie new by the time of one timer tick 0 5us the compare value that has to be written to OCR1B 9 is 4251 The interrupt service routine ISR TIMER1_COMPB_vect that gets called every time a compare match B interrupt occurs contains only one line where the compare value is increased by 4251 Otherwise Counter1 would first count to 2 and again to 4251 to trigger an interrupt so that a signal with another frequency than fsampie new Would be generated 19 3 2 3 Calculating the Difference and the Average Within the interrupt service routine ISR of the ADC alternately the value of a maximum is saved to variable top and the voltage difference between maximum and minimum is directly saved to variable diff by subtracting the latest minimum value from the before saved maximum value top For building the sum out of the constantly new calculated differences variable diff a buffer with the size of eight is used where the la
41. er Mobiltelefon f r Personen die an einer Tetra oder Paraplegie der oberen Extremit t leiden zu vereinfachen F r das neue Eingabeger t wurde ein Sensor welcher ber eine Infrarotdiode Licht emittiert und das von einem Objekt reflektierte Infrarotlicht mittels Fototransistor detektiert verwendet Um den m glichen Einsatzbereich des Sensors zu ermitteln wurden zahlreiche Messungen durchgef hrt welche als Ergebnis den Bereich der h chsten Sensibilit t zwischen 5mm und 30mm lieferten Um den Einfluss des Infrarotanteils des Umgebungslichtes zu reduzieren wird die Infrarotdiode gepulst betrieben und das Signal des Fototransistors ber einen Schwingkreis zu einem sinusf rmigen Signal modifiziert Da auch Personen die an einer Tetraplegie leiden die neu entwickelte Eingabehilfe verwenden k nnen sollen wurde das Kinn gew hlt um das Infrarotlicht zu reflektieren Je nach Entfernung von Kinn zu Fototransistor f llt mehr oder weniger Spannung ber dem Fototransistor ab Diese Spannungs nderung wird in den Analog zu Digital Konverter eines ATMEL 8 bit AVR Mikrocontroller AT90USB1286 auf einem Teensy Development Board Teensy 2 0 gef hrt Nach einer Mittelwertbildung der Messwerte k nnen die Werte an die Softwareplattform AsTeRICS Runtime Environment ARE versendet werden Die Kommunikation zwischen neu entstandenem Communication Interface Module CIM und PC findet ber eine USB Verbindung und ein spezielles Kommunikationsprotokoll
42. f r Entwickler 3 Auflage REDLINE GmbH Heidelberg 2007 p 99 102 120 11 Universal Serial Bus Specification Revision 2 0 April 2000 http www usb org developers docs Date of last visit 24 4 2013 p 260 274 12 http www usb org developers defined class Date of last visit 24 4 2013 Contact details Martha Keizur USB Implementers Forum Inc Kavi Corporation 225 SE Main Street Second Floor Portland OR 97214 privacy usb org 13 Universal Serial Bus Class Definitions for Communications Devices Revision 1 2 November 2010 http Awww usb org developers devclass_docs Communication Device Class Date of last visit 24 4 2013 p 15ff Contact details see 8 14 Comments of the file usb serial c http www pjrc comi teensy usb serial html gt USB Serial Version 1 7 Date of last visit 24 4 2013 40 List of Pictures Picture 1 Example of an ACS model consisting of a sensor FacetrackerLK tracks the position of the nose or the chin via a web cam a processor Averager stores a defined number of values that arrive at the input port averages them and sends the value via the output port and an actuator Mouse the mouse pointer movements in horizontal direction are now carried out via the horizontal movements of the user s nose ese ee ee ee ee 7 Picture 2 Reflective object sensor QRD 1114 dimensions 6 1 x 4 39 x 4 65mm weight 2g 7 Picture 3 Teensy 2 0 Development Board with header pins 7
43. g the PCB fixed on the dedicated head mounting Picture 23 Sensor mounted on the head 32 On Picture 22 one can see the box that is fixed on the dedicated head mount After donning the dedicated head mount the sensor can be placed in the neutral position of the chin by bending the mounting wire Picture 23 shows the sensor mounted on the head and Picture 26 shows the optimal distance between sensor and chin at the neutral resting position By moving the chin to the left closer to the sensor or to the right away from the sensor the amount of reflected infrared light increases decreases and therefore the according values that are sent from the CIM change Picture 24 shows the screen shot of the ACS model that makes the mouse pointer movement possible At this point the working principle of all the components together should be described For more details about the components and their functions see Chapter 2 3 The Slider component is only used if the corresponding sending mode sending events see Table 4 was chosen As for the mouse pointer movement only the sending mode that sends continuous values see Table 4 is used the Slider as well as the EventVisualizer component are not needed for the explanation of the working principle Starting at the Proximity component representing the proximity sensor the continuously sent values representing the distance between object and sensor are sent to the MathEvaluator component There the
44. ght Picture 7 Picture 8 and Picture 9 The reflective object sensor QRD1114 reaches its maximum of current flow with a reflecting object at a distance of 25mils 0 635mm 3 and a maximum of voltage drop within Omm to 5mm using a 2200 series resistor before the infrared LED Picture 9 Picture 2 Reflective object sensor QRD 1114 dimensions 6 1 x 4 39 x 4 65mm weight 2g 2 2 Teensytt 2 0 Development Board The Teensytt 2 0 Development Board is a microcontroller development system that is completely based on USB To connect the Board to a PC only a standard Mini B USB cable is necessary It is either available with only solder pads for all VO signals or with header pins that are already soldered onto it 6 Its key features are an AVR processor with 16MHz clock frequency the possibility of single push button programming combined with the very easy to use Teensy Loader application the free software development tools and the fact that due to the USB connection it can be any type of device 7 Specifications can be found on the table below Table 1 Processor AT90USB1286 8bit AVR 16MHz Flash Memory 130048 RAM Memory 8192 EEPROM 4096 VO Number 46 5 Volt Analog In 8 PWM 9 UART l2C SPI 1 1 1 Price 24 Table 1 Key features and specifications of the Teensy 2 0 Development Board 7 ro FE FAS FA FS FO FI kc PAO PAT PA2 PAS Qeooe e00 o PAs PAS PAG Pa f
45. he average is calculated usb_serial c The usb serial c file can be downloaded from the Teensy homepage 14 It contains the data that is necessary for the enumeration process descriptor data see Chapter 3 2 5 and so called public functions that simplify the usage of the Teensy Development Board For the implementation of the proximity sensor only five of them are used The first one is called usb init and is activated in the main function of the ProximityCIM c file As the name already implies it initializes the USB serial The second function named usb configured returns zero ifthe USB is not configured or the configuration number that was selected by the host In the ProximityCIM c file it is used within a while loop As long as zero is returned the program stays there The third function is called usb_serial_available and returns the number of bytes that are available in the receive buffer It is used in the cimprotocol c file to identify if there are bytes sent from the ARE that can be parsed If there are bytes in the receive buffer the fourth function is used The so called usb_serial_getchar function is used to get the next character out of the available bytes in the receive buffer The last used function is called usb_serial_write and is used to send a packet from the CIM to the ARE CimProtocol c For a more detailed description of the CimProtocol see Chapter 3 2 4 This source file can be divided into two
46. hey stop counting after exiting the dead zone again or after the defined time period has passed and an event has been triggered Slider With the Slider component it is possible to generate a slider of any size with an adjustable range of values on the ARE desktop Connecting its only output port to the input port of a component that is designed for the sliders values it can be used to change parameters of the model during runtime With regard to the proximity sensor the slider is used to adjust the value of the threshold that is necessary to send events if the corresponding sending mode was selected see Table 4 2 3 3 Utilized Actuators Mouse This component facilitates the movement of the mouse cursor and the clicking process on the computer the ARE is running on The three different input ports and the event listener port cursor movement x direction cursor movement y direction press release action provide the mouse functions WavefilePlayer The WavefilePlayer has one input port and one event listener port After receiving an event a before specified wav file is played on the platforms sound output In case of the proximity sensor a sound is played every time the user stays within the dead zone for the defined time period that causes an event Oscilloscope This component can display one or two signal values The trace color and update speed of the signal that enters the component via its input port can be configured via the compone
47. horizontal to vertical and the other way around For changing the direction once it is necessary to stay within the dead zone for 600ms After the direction has been successfully changed signalized due to an acoustic signal generated by the WavFilePlayer component the user has to exit the dead zone again to move the mouse pointer in the desired direction Staying within the dead zone longer than 600ms Timer 1 1 is called into action Timer 1 1 triggers an event after 1500ms This event has two consequences On the one hand the direction of the mouse pointer movement is set to horizontal movement x direction This is necessary as waiting 1500ms within the dead zone means that after 600ms the direction of the mouse pointer movement is changed automatically due to Timer 1 On the other hand the triggered event causes a mouse action This could either be the kind of click that was chosen via the ButtonGrid component or a 33 normal double left click If no special click function was chosen on the ButtonGrid every click that is generated after waiting 1500ms is a normal double left click Clicking successfully also generates an acoustic signal For enabling disabling of the proximity sensor as mouse control another button on the ButtonGrid is provided This can for example be used to allow a technician to modify the ACS model with a standard mouse Picture 24 AsTeRICS ACS model for mouse control The picture below Picture 25 shows the graph
48. ical user interface of the mouse control model Slider to define threshold 400 600 800 oscillascope Oscilloscope AdjustmentCurve Current value ButtonGrid Picture 25 Graphical user interface oft he ASC model for mouse control Besides the model for controlling the mouse there already exist two other ready to use models within the ACS One of them is a simple test model that provides an oscilloscope to display the values that are sent from the sensor an event visualizer to display incoming events a bar display to visualize the current signal value that is sent from the CIM and it also provides a Slider component to define the threshold The other model is a model to play pinball This model equals the mouse control model with the exception that the 34 AdjustmentCurve component is followed by two Comparator components Those Comperators have a defined threshold One of them triggers an event if the threshold 20 is exceeded and the other one triggers an event if the threshold 20 is succeeded Exceeding the threshold leads to local keyboard input of L on the computer the ARE is running on Now the right bouncer can be moved Succeeding the threshold a keyboard input of A is generated to move the left bouncer Picture 26 shows the sensor mounted on the head chin in neutral position The next picture Picture 27 shows the chin movement closer to the sensor and therefore the mouse pointer moveme
49. id component button Init it saves the current value that arrives via the input port The stored value should equal the neutral point of the chin and therefore the neutral position of the mouse no movement MathEvaluator This component consists of four input ports and one output port Values that arrive via the input ports can be used for every mathematical expression the user wants to express and the result of the mathematical expression is delivered to the output port In case of the proximity sensor two input ports are used The value that is saved in the SampleAndHold component is subtracted from the current value that is sent from the Averager This subtraction makes it possible that the movement of the chin can be interpreted as negative equates to mouse movement to the left and positive equates to mouse movement to the right values around the neutral point StringDispatcher The StringDispatcher component provides one input one output and one event listener port After receiving an event from the ButtonGrid component and after an individually defined delay it sends the appropriate information through the output port In the model that was designed for the proximity sensor the StringDispatcher component delivers information about the next click double click right click drag click to the mouse component PathSelector The PathSelector has one input one event listener and four output ports The component provides the op
50. ight are blinded out Furthermore the resonant circuit transforms the by the phototransistor detected square wave signal into a 15 nearly perfect sinus shaped signal Picture 11 green graph For the dimensioning of the parallel resonant circuit the resonance frequency fr correlates to the frequency of the pulsed infrared LED Therefore for further calculations one has to assume fr 10kHz Starting with the dimensioning of the resonant circuit either the value of the inductor Lr or the capacitor Crcan be chosen first In this case Lp was defined first LA 10mH 1 LEE er Formula 4 2 1 7 L fr 27 Formula 5 C By using Formula 4 8 and transforming it to Formula 5 it is possible to calculate the right value for C By applying the values of fg 10kHz and Lr 10mH to Formula 5 the equation delivers the capacity Cr 25nF An available capacitor that fits best to this value has the capacity Cr 22nF Additionally to the parallel resonant circuit the operating point has to be raised to 2 5V so that the signal oscillates around 2 5V This raising of the operating point has to be done with regard to the later use of the signal as input to the analog to digital converter of the microcontroller were the reference voltage Vre reaches from a minimum of OV to a maximum of 5V and therefore negative values can not be converted Further the maxima and minima of the sinus shaped signal are measured Picture 11 red lines and subtracted so that ther
51. im is to offer a flexible framework for Assistive Technologies that can be easily adapted to the needs of 5 users with motor disabilities Besides the hardware components including sensor and actuator modules e g camera switch Communication Interface Modules CIMs interfaces to connect sensors actuator to computing platform and a computing platform to run the AsTeRICS software there exists a software framework This software framework consists of the AsTeRICS Runtime Environment ARE and the AsTeRICS Configuration Suite ACS 4 1 1 1 AsTeRICS Runtime Environment ARE The ARE as the basic software framework is an OSGi based middleware www osgi org The ARE is necessary to run different plugins programmed in JAVA representing sensors or actuators which can be combined to AsTeRICS applications the so called models The plugins are implemented as independent OSGi bundles and the OSGi based middleware makes it possible to run the software plugins in parallel The runtime environment also starts and stops the operation of the plugins The structure of a plugin properties inputs outputs and event ports is defined in XML files which are also the base for the OSGi middelware to construct a runtime representation of an installed plugin Furthermore there exists another XML file that comes from the ACS and represents a runtime model system model Due to the information provided by this system model XML file the ARE
52. ing to Table 3 Reaching the end of the packet the second part of the CIM protocol is carried out 2 In this second part depending on the command that was sent with the packet from the ARE the addressed feature is carried out including the sending of an answer packet that is sent from the CIM to the ARE The answer packet is generated also according to the packet format of Table 3 The following table Table 4 provides an overview and short descriptions of the features that are realized in the new developed CIM called proximity sensor Teensy_CIM_Feature 0 0x00 Read feature reading unique number from _UniqueNumber CIM Teensy_CIM_Feature Write feature writing threshold to CIM needed 2 0x02 _Set_Threshold for event generation Write feature writing mode of operation to CIM Choice by sending following values to CIM 02 CIM will send continuous values average of eight diff values see Calculating the Difference and the Average 2 0x06 1 gt CIM will send an event 1 if the second of two immediately consecutive values exceeds the before set threshold 2 gt CIM will send an event 0 if the second of two immediately consecutive values succeeds the before set threshold 3 gt Combination of point 1 amp 2 Table 4 List and description of the CIM features that are provided by the new developed CIM called proximity sensor Teensy_CIM_Feature Mode Selection 21 Calculati
53. is finished here break case 11 read out data ARE_frame data datapos actbyte datapos if datapos ARE_frame data_size if transmission_mode amp CIM_STATUS_CRC with CRC get checksum readstate else readstatesFRAME DONE no CRC frame is finished here break case 12 checksum byte 1 checksum actbyte readstate break case 13 checksum byte 2 checksum long actbyte lt lt 8 readstate break case 14 checksum byte 3 checksum long actbyte lt lt 16 readstate break case 15 checksum byte 4 checksum long actbyte lt lt 24 Il check CRC now currently not used llif checksum crc32 ARE_frame data ARE_frame data_size reply status code CIM ERROR CRC MISMATCH Il frame finished here readstate FRAME_DONE break default readstate 0 break 52 if readstates sFRAME DONE frame finished store command in ringbuffer process_ARE_frame reply_status_code readstate 0 53
54. knows which plugins it has to activate and how the data flow between them has to be defined The communication between the ARE and the ACS takes place via a TCP IP based communication protocol named ASAPI Other services for plugin developers that are provided by the ARE are for example a communication support for COM ports for the connection of the CIMs reporting errors that occur on the runtime environment and interacting with the graphical user interface ARE GUI This graphical user interface makes it easier for end users to manipulate the ARE 4 5 For more information see AsTeRICS User Manual 4 p 14 and AsTeRICS Developer Manual 5 p 8 9 1 1 2 AsTeRICS Configuration Suite ACS The ACS is used to create new models for the ARE Also these models can be manipulated started stopped and uploaded downloaded to from the ARE in the ACS The ACS can but does not need to run on the same computer as the ARE For the usage of the ACS there are some terms that are important to know 4 Plugins pieces of software are needed to communicate with a device and to perform certain calculations 4 Components can be divided into three types o sensors are the source of data flow in an AsTeRICS model The newly developed component that is described in this work belongs to the group of sensors processors are used to manipulate the data from a sensor or another processor in a way to deliver new output data for other processors or
55. l limitations was developed to access education and to participate in social life more easily Keywords Assistive Technology alternative input device reflective object sensor Teensy Development Board EU project AsTeRICS Table of Contents N ere se ses ee regen 5 Vet IBACKG FOUND ER EN a HR ME OER ER toned 5 1 1 1 AsTeRICS Runtime Environment ARE esse esse ee ee se ee ee ee ee ee ee Re ee ee de de ee Re ee de ee 6 1 1 2 AsTeRICS Configuration Suite ACS see ee see Ee ee ee Ee ee ee ee ee ee ee 6 2 Materials EE IR AE OR ER OE AA NE 7 2 1 Reflective Object Sensor ORDT TA ee ee ee ee 7 2 2 Teensytt 2 0 Development Board is ee ee ER AR RE ee ee ee Re RR ER ee ee ee ee ee 8 2 3 Components of the AsTeRICS ACS model that is used with the Proximity Sensor 8 2 3 EEU Ee N ad vele Ee AE EE ER EE ee ehh leet eee ee 9 2 39 23 Utilized S nso ricer ER OE OE EE EE OO ESER 10 2 3 3 Utilized Actuators EE ER ee re ee 11 3 ul E a aa nenne a aeee easain iat 11 3 1 Testing Sensor Properties ee 11 3 1 1 Permanent Shining Infrared LED of the QRD 1114 ee 11 3 1 2 Pulsed Infrared LED of the QRD 1114 and Dimensioning of the Parallel Resonant Circuit 15 3 2 Programming of the Microcontroller Firmware iss see ee ee Re ee ee ee nennen 18 3 2 1 Generating the Output Signal of 9 174KHZ ee ee ee ee ee 18 3 2 2 Measuring Maxima and Minima Triggering the ADC
56. l measurements were carried out Those measurements brought up the most sensitive area at distances between 5mm and 30mm For a minimization of the ambient light s fraction of infrared light the infrared diode is pulsed The signal that leaves the phototransistor is lead through a parallel resonant circuit in order to achieve a sinus shaped signal As also persons who suffer from a Tetraplegia should be able to use the new alternative input device the chin functions as the object that reflects the infrared light Depending on the distance between sensor and chin either more small distance or less greater distance voltage drops across the phototransistor These changes of voltage drop are sent to the digital to analog converter of an ATMEL 8 bit AVR microcontroller AT90USB1286 mounted on a Teensy Development Board Teensy 2 0 After averaging the measured values they are forwarded to the software platform AsTeRICS Runtime Environment ARE The communication between the new built Communication Interface Module CIM and the PC is carried out via an USB connection and a special communication protocol For the new input device being compatible with the ARE and the ACS AsTeRICS Configuration Suite necessary to build a model that converts the values of the new distance sensor to mouse pointer movements also the corresponding software had to be developed With this new alternative input device a new opportunity for people who have physica
57. main parts The first part is implemented in the function parse_CIM_protocol and is used for the analysis of a new arriving packet that was sent from the ARE to the CIM After recognizing the two synchronization bytes and T one after the other the parsing of the packet goes on Now variables are filled up with the right byte according to Table 3 Reaching the end of the packet the second part of the CIM protocol is carried out The second part implemented in the function process ARE_frame is used to carry out the addressed feature that was defined by the command that was sent with the packet from the ARE This includes the sending of an answer packet that is sent from the CIM to the ARE 25 The answer packet is generated also according to the packet format of Table 3 Table 4 provides an overview and short descriptions of the features that are realized in the new developed CIM called proximity sensor However there are also features to start stop or resume the CIM Starting the CIM means that the timers and the ADC get initialized and the timer that is used for the sampling process is started With the feature stop CIM only the timer that is used for the sampling process is stopped ProximityCIM c This source file is the one that contains the main function It calls up the before mentioned functions that are needed to initialize the ADC and the timers Further it calls up the functions that are needed to generate th
58. nce can be found at distances above 30mm There the influence of the amount of infrared light in daylight gets displayed Even at big distances over 30mm the phototransistor detects infrared light This effect is even better observable in Picture 9 where the measurements of R with and without daylight cloudy sky no direct sunlight are compared directly Due to the amount of infrared light in daylight a higher voltage drop over the phototransistor occurs Picture 9 blue graph at higher voltages than red graph As for the planned application an operating range above 30mm is not needed and a bigger series resistor lengthens the lifespan of the infrared LED all further measurements and circuit designs are done using the 2200 series resistor R4 3 1 2 Pulsed Infrared LED of the QRD 1114 and Dimensioning of the Parallel Resonant Circuit To get rid of the influences caused by the amount of infrared light in the daylight the infrared LED got pulsed with a square wave signal frequency 10kHz Picture 11 orange graph that is produced by the microcontroller This pulsing of the diode works together with the parallel resonant circuit to blind out the fraction of infrared light that is present in ambient light This is possible as the resonant circuit can only be induced by the very special frequency of the pulsed diode Therefore not only the fraction of infrared light that is present in the ambient light but also all other frequencies of surrounding l
59. nd the other time with the proximity sensor For this use case the mouse model was changed a little bit no oscilloscope no slider to set the threshold and no event visualizer Also the graphical user interface was moved to the right side of the screen A screen shot of the graphical user interface the browser window and the on screen keyboard used with the proximity sensor can be seen on Picture 29 The results of this test can be found on the table below Table 7 WEER DE ET Tr ae AnTeRilS Quick Saart Gude p ing ee ie Modet Opus About e Een ee end ee vele meme 33 Plr n Enable disable DOUBLECLICK RIGHTCLICK DRAGCLICK 2012 08 21 co CERES Quick Start Guide AsTeRICS Ea DER o EE WEE le Fr j BEET Picture 29 Screen shot of the use case Searching and downloading a file from a homepage On the right side of the screen the graphical user interface is illustrated At the bottom one can see the OSKA on screen keyboard and at the top the browser window was placed 7min 3min 40sec Table 7 Time that is needed to search and download a file on the Internet One time the proximity sensor was used the other time a one switch mouse 36 5 Discussion and Conclusion With the new built alternative input device called proximity sensor another possibility to use a PC for people with physical limitations was developed Using a refl
60. ng the transmission freguency from the CIM to the ARE during the mode of operation where the average of eight diff values is continuously sent see Table 4 it has to be considered that one time Tsampie new 2 1255ms is needed to get the value of one maximum saved in variable top To sample the corresponding minimum and calculating immediately the difference out of those two values maximum minimum Tsampie new goes by a second time So to get one value that can be saved in variable diff 4 251ms elapse As always the average of eight diff values is sent or in other words the sending process always starts when the buffer size of buffer 8 is full the 4 251ms have to be multiplied by eight If the buffer is full the average is calculated and sent Between two sent average values Tgending Tsample new 8 34ms go by This Tsending equates to a sending frequency fsending 1 Tsending Of 29 4Hz 3 2 5 Communication of the Teensy USB Development Board Teensy 2 0 The Teensy USB Development Board Teensy 2 0 uses the ATMEL 8 bit AVR microcontroller AT90USB1286 with a system clock frequency of 16MHz For the communication with the PC host a USB connection is used This makes the usage of the Teensy Development Board very easy and comfortable The board provides a programmable USB connection enabling the developer to implement several USB device classes on the board These classes can be recognized on the PC
61. nt s parameters EventVisualizer With the EventVisualizer component events can be graphically displayed due to a simple text output that shows the names of the events It is mainly used for testing the configurations during setup time With regard to the proximity sensor it displays events that are produced after the corresponding sending mode Table 4 has been selected 3 Methods 3 1 Testing Sensor Properties 3 1 1 Permanent Shining Infrared LED of the ORD 1114 First of all it was necessary to measure the ratio of distance between object and sensor and the resulting output voltage This ratio helped to detect the most sensitive area in front of the sensor and therefore gives indication of the right adjustment in the near of the head more precisely in the near of the chin In order to see if surrounding sunlight daylight influences the output voltage the measurement was once taken with closed sun blinds and once taken 11 with opened sun blinds Also the forward current I through the infrared diode was changed for the purpose of varying the intensity of the emitted light To change the value of Ir different series resistors were used According to the test conditions of the sensor s datasheet 3 the first tested Ir was 15mA Increasing Ir to IF 2 27 5mA and IF 3 36mA increased the intensity of emitted infrared light Knowing the maximum forward voltage Vr of the diode Vr 1 7V 3 and the operating voltage Vor of the whole system
62. nt to the left Picture 28 shows the movement to the right Picture 26 Sensor mounted on the head chin in neutral position f eo ig dy AA Picture 28 Sensor mounted on the head chin moved to the right away from the sensor The table below Table 6 shows the performance data of the proximity sensor with the mouse control model It was used with an on screen keyboard and the characters that could be typed per minute at the first usage and after a little training 10 time usage are shown Also a comparison to the usage of on screen keyboard scanning methods and a single push button is included 35 EERDER First time usage of the proximity sensor with the 26 mouse control model and an on screen keyboard 10 time usage of the proximity sensor with the 54 mouse control model and an on screen keyboard On screen keyboard with scanning method and 50 single push button Table 6 Performance data of the proximity sensor used with an on screen keyboard 1 and 10 time usage compared to the performance data of a single push button with an on screen keyboard and a scanning method To test the performance of the mouse control even more it was the task to open the AsTeRICS homepage via Google and on screen keyboard and to further open the Quickstart Guide on page six scrolled via the drag amp drop function that can be found in the menu Downloads and Manuals One time it was opened with a one switch mouse a
63. ontal as well as vertical directions Furthermore one can decide what kind of click should be carried out next There are three possibilities double click left right click and drag click After the chosen click was carried out the next click will be a double click as it is set as standard click Before the proximity sensor could be used on the designed PCB the printed circuit board was tested This brought up some problems that were related to the SMT surface mount technology 22nF capacitors Table 5 and Picture 15 C3 and C4 of the parallel resonant circuit Although the chosen SMT capacitors were film capacitors and have the same properties according to their datasheet like the normal sized through hole capacitors they do not show the same behavior at the frequency of 9 174kHz This could either be caused by the capacitors tolerances or by a production fault To solve the problem the SMT capacitors were replaced by the through hole capacitors that were used on the pinboard After this exchange the proximity sensor could be used as it was planned As shown in the results after a little training with the proximity sensor the mouse pointer movements can be carried out rather fast This is also good for applications that include an on screen keyboard e g Oska The on screen keyboard can be used directly instead of using it with scanning methods 1 Although there is not a big difference in the number of characters that can be written when
64. ounting wire is soldered onto the plane that can be seen on the picture above Approximately at the middle of 4WAY HEADER 2 it is bent to 90 and leaves the PCB Picture 18 At the other end of the mounting wire the reflective object sensor QRD1114 is placed Picture 18 For the protection of the contacts that are going into the sensor about three to four centimeters of wires before they enter the sensor are stuck together with hot glue Picture 18 Afterwards all the wires mounting wire signal wires were conted with a end hose Piaure 19 Picture 18 PCB with connected mounting wires and Spc wires with hot glue stabilized sensor contacts no shrinking hose Picture 19 PCB with connected onta wires and signal wires shrinking hose over s mounting and signal wires 31 4 Results Picture 20 and Picture 21 show the PCB in the box that protects it against damage The box was only adapted from an already existing SolidWorks model The adaption includes two holes for plugging in the wires USB plug and Jack Plug 3 5mm and one hole for the mounting wire tale forthe ountingsiiis an Picture 20 Box for fixing the PCB on the dedicated head mounting and protecting it against damage Box open holes for USB plug Jack Plug 3 5mm and for the mounting wire Hale ia PIDLNUNE WITE Picture 21 Box for fixing the PCB on the dedicated head mounting and protecting it against damage Box closed Picture 22 Box containin
65. ped signal oscillates not exactly around 2 5V Indication for this fact is that the values of the maxima never come as close to the 2 5V as the values of the minima do Therefore the sinus shaped signal oscillates around a voltage value that is bigger than 2 5V However looking at the green graph delta it is easy to see that the area of the highest sensitivity can be found again between 5mm and 30mm 3 2 Programming of the Microcontroller Firmware 3 2 1 Generating the Output Signal of 9 174kHz For the generation of the output signal pulsing the infrared LED the Timer Counter1 was used because of its feature of being a 16 bit Timer Counter and providing three independent output compare units one of them is used for signal generation and one is used for ADC triggering see Chapter 3 2 2 Measuring Maxima and Minima Triggering the ADC 9 This assures that for both signals 9 174kHz signal to pulse infrared LED and the signal that is used as trigger source for the ADC Counter1 starts at the same moment to count To make further calculations easier a prescaler of eight is used Register TCCR1B gt Bit CS11 1 9 Dividing the system clock frequency of 16MHz by eight gives a new frequency of 2MHz The periodic time of this frequency is 0 5us which equals now one timer tick of Timer Counter1 With this knowledge it is possible to calculate the compare value starting with the required frequency of 9 174kHz that has a periodic time of 10
66. portunity to link the input port numerical signal with one of the four output ports The output port that should be linked with the input port can either be chosen directly by a dedicated event listener port or by using the event listener port the link connection is switched to the next or the previous output port This enables the user to fulfill two dimensional mouse cursor movements After staying within the dead zone of the curve for a defined time period of 600ms component Timer 1 the next output port is linked with the input port Depending on the linked output port the mouse component knows if the upcoming chin movement should be interpreted as movement into the horizontal or vertical direction Deadzone The Deadzone component can also be called resting zone With this component one is able to define active and passive zones where the mouse pointer should move or not It has three input and two output ports and one event trigger and event listener port each 9 To move the mouse pointer it is necessary to exceed a defined value of a sensor Using the component with two dimensional values as it is the case with the proximity sensor the Deadzone component can be described as a number line After defining the zero point on the scale the radius 0 5 of the in this case passive zone around the zero point can be specified For the usage of the proximity sensor only the event trigger port is used as output port From this por
67. rts of the component and to set or get it s supported properties 5 The plugin code of the proximity sensor contains the following component support methods 28 public IRuntimeOutputPort getOutputPort String portID This method is needed by the ARE to get the connection to the output port Referencing to the port with the corresponding ID carries out the process of connecting to the port public IRuntimelnputPort getinputPort String portID This is a necessary method to connect the ARE with the input port For further description see method IRuntime OutputPort getOutputPort public IRuntimeEventTriggererPort getEventTriggererPort String eventPortID To get the connection between ARE and the event trigger port this method is needed For further description see method IRuntime OutputPort getOutputPort public Object getRuntimePropertyValue String propertyName This function is necessary for the manipulation of internal component properties that have an influence on the process implemented in the component public Object setRuntimePropertyValue String propertyName Object newValue The values of the component properties threshold sending mode that are chosen via the ACS and imported to the ARE are sent to the proximity sensor Before sending the values they have to be included into a CIM packet that was build regarding to the CIM protocol public void handlePacketReceived CIMEvent e This method is needed for th
68. se descriptors see 13 Chapter 5 2 3 23 Enumeration Process This chapter provides just a short overview about the process of how the host detects and connects a new attached USB device After plugging the device into one of the hosts USB ports it is recognized due to a voltage change within the USB port Now the device is powered While the port of the new device is reset the host gets the information in which mode full or high speed mode the device is going to communicate After resetting the device it remains in the state of default until the host sends a request to get further information of the descriptors Now the host allots an explicit new address to the device The entire communication between host and device is processed via this address 10 As all USB devices have to have a serial number a vendor ID and a product ID the host is able to create anew COM port on Windows for every unique combination of those three parameters For the creation of a new COM port on Windows the so called inf file is necessary Normally a device of the communication device class CDC is able to create a COM port on its own but Windows set the inf file as a standard One device always gets the same COM port number as the host remembers each serial number Data that should be sent is filled into an USB endpoint buffer first The data of the endpoint buffer is transmitted to the host when it becomes full or if there is a timeout with no more writes
69. t threshold generate_EventFrame 1 else if oldVal gt threshold amp amp value lt threshold generate_EventFrame 0 break oldVal value Timer c E AsTeRICS Proximity CIM Firmware using Teensy 2 0 Controller board file Timer c Version 0 1 Authors Chris Veigl FHTW Franziska Horak Date 30 04 2013 7 include lt avr io h gt include lt avr interrupt h gt void Timer_Init void TIMSK1 0 TIFR1 1 lt lt 2 1 lt lt 1 TCNT1 0 OCR1A 109 Wert bei dem der Compare Match Interrupt LED ausgel st wird vorher Reload Value 149 gt 256 149 107 OCR1B 109 40 Wert bei dem der Compare Match Interrupt ADC das erste Mal ausgel st wird TCCRIA 1 lt lt 6 OC1A toggeln bei Compare Match keine PWM alle WGMn Bits sind 0 TIMSK1 1 lt lt 1 1 lt lt 2 Output Compare A und B interrupt enabled void start_timer1 TCCRIB 1 lt lt 1 Prescaler 8 gt 1 Timer Tick 0 5us void stop timer1 TCCRIB 0 ISR TIMER1_COMPA_vect OCR1A OCR1A 109 ISR TIMER1_COMPB_vect IIPORTD PORTD 1 lt lt 5 OCR1B OCR1B 4251 Adc c je AsTeRICS Proximity CIM Firmware using Teensy 2 0 Controller board file Adc c Version 0 1 Author Chris Veigl FHTW Franziska HOrak Date 30 04 2013 include lt avr io h gt include lt avr interrupt h gt define BUFSIZE 8 volatile uint16_t ADC_updates 0 counts ADC
70. t events are sent every time the current value enters or leaves the defined radius AdjustmentCurve This component consists of two input ports and one output port It shows the user the curve that is produced by the usage of any alternative input device sensor that provides two dimensional values Due to some sensor properties or anatomical conditions of the user it could be the case that the values in one direction away from the neutral point zero point of resting zone scale are different e g in terms of acceleration to those in the opposite direction With the AdjustmentCurve component it is possible to compensate such differences and to further adjust the values that represent the mouse pointer movement Furthermore the output values of this AdjustmentCurve component are used as input signal of the Deadzone the PathSelector and the Oscilloscope component to display the current values 2 3 2 Utilized Sensors AutostartEvent This component provides only one event trigger port and sends an event after the whole model is started The moment for sending the event can be chosen individually due to defining a delay For the usage of the proximity sensor a delay of 1000 seconds was chosen ButtonGrid The ButtonGrid works like an on screen keyboard with the special feature that the keys can be defined individually It provides only one port an event trigger port Via this port events are sent after buttons are pressed The keys that
71. ted ARE reply status code CIM_ERROR_INVALID_ARE_VERSION readstate break case 4 data length low byte ARE_frame data_size actbyte readstate break case 5 data length high byte ARE_frame data_size uint16_t actbyte lt lt 8 if ARE_frame data_size gt DATABUF_SIZE dismiss packets of excessive length readstate 0 ARE_frame data_size 0 Ireply_status_code CIM_ERROR_INVALID_FEATURE else readstate break case 6 serial_number ARE_frame serial_number actbyte if first packet don t check first serial first_packet 0 else if actbyte last_serial 1 0x80 check current serial number reply status code CIM ERROR LOST PACKETS last serialsactbyte readstate break case 7 CIM feature low byte 51 ARE frame cim features actbyte readstate break case 8 CIM feature high byte ARE_frame cim_feature int actbyte lt lt 8 readstate break case 9 Request code low byte command ARE_frame request_code actbyte readstate break case 10 Request code high byte transmission mode transmission_mode actbyte bit 0 CRC enable lI reply_status_code actbyte amp CIM_STATUS_CRC Il remember CRC state for reply if ARE_frame data_size gt 0 readstate datapos 0 else no data in packet if transmission_mode amp CIM STATUS CRC readstatet 2 proceed with CRC else readstate FRAME_DONE frame
72. test eight values of diff are saved Due to this buffer a currently updated value for sum can be provided Therefore the oldest value of diff is cleared out of variable sum by subtracting it Then the latest value of diff is added to variable sum Every time the buffer is filled again with new diff values variable sum is divided by the size of the buffer buffer size eight in order to calculate an average 3 2 4 Communication Protocol and Features During the development of the project AsTeRICS a communication protocol was implemented This protocol is needed for the communication between the AsTeRICS Runtime Environment ARE and external modules Communication Interface Modules CIMs via the USB standard interface communication via USB CDC virtual serial ports Therefore this communication protocol is also called CIM protocol The CIM protocol is a bi directional communication standard that is needed for the usage of available services for connection and communication that are provided by the ARE as well as it is needed to define the unique ID for the CIM type Furthermore the protocol is necessary to read or write so called features from to the CIM 5 The following table Table 3 shows the format of a CIM protocol packet Data field Packet ID 2 T 0x4054 Identifier of the beginning of a new packet Packet from ARE gt CIM ARE ID identification of ARE ARE I
73. th ISRs contains only one line that increases the compare match values of OCR1A and OCR1B every time by the initialization value in order to generate the needed wanted frequencies Otherwise there would only be a compare match interrupt when the counter reaches the initialization value 24 Adc c This source file contains a function that initializes and configures the ADC and clears the buffer that is used to store the eight most recent diff values The configuration includes enabling the ADC auto trigger mode conversion always starts at positive edge of the chosen trigger signal and the ADC interrupts It further contains the configuration of the ADC clock register ADCSRA the source of the reference voltage ADMUX and the signal that should be used for triggering Timer Counter1 Compare Match B Within the ISR that is carried out after a conversion is completed alternately the measured values for a maximum and for a minimum are saved Further the difference of the latest two values is calculated The calculated differences are saved into the buffer and added For a more detailed description of this computing process see Chapter 3 2 3 Ifthe buffer is full eight values are saved the variable ADC_updates is set to one As a result of the setting to one within the ProximityCIM c file the last function of the Adc c file is carried out This function divides the sum of eight diff values by the size of the buffer eight and therefore t
74. urce of the reference voltage is chosen as AREF pin with the internal Vref turned off register ADMUX 12 Bits REFSO 1 Thirdly pin ADC3 that is used as analog input pin is defined by writing the Bits MUXO and MUX1 in the ADMUX register 9 to 1 Also the ADC auto trigger mode has to be enabled by setting the ADATE Bit of the register ADCSRA In this mode the ADC will always start a conversion on a positive edge of a selected trigger signal The trigger signal itself is defined in the ADCSRB register 9 Writing the bits ADTSO and ADTS2 to one selects Timer Counter1 compare match B as trigger source In the ADC auto trigger mode a whole conversion takes 13 5 cycles 2 cycles of the 13 5 cycles at the beginning of the conversion are needed for sample amp hold 9 Table 25 1 Those 13 5 cycles multiplied by the periodic time of the ADC clock 4us give a conversion time of 54us As the time from one maximum to one minimum of the sinus shaped signal is only 0 5us longer than the conversion time it would be theoretically possible to measure every of the maxima minima However for the future application it is not necessary to have about 18 000 values per second available Hence the compare value of Timer Counter1 compare match B that is written to the output compare register OCR1B has to be calculated Instead of sampling the sinus shaped signal with a frequency of 9 174kHz every 54 5us sampling rate 18 34kHz a sampling rate of about 500 samples p
75. values ADC_updates measure_top 1 uint16_t mittl_berechnen if sum lt 0 measure_top measure_top return 0 this is a workaround for the init comparematch problem return uint16_t sum BUFSIZE cimprotocol c i AsTeRICS Proximity CIM Firmware using Teensy 2 0 Controller board file CimProtocol c Version 0 1 Author Chris Veigl FHTW Franziska Horak Date 30 04 2013 AsTeRICS CIM Protocol Packet Frame Packet ID 2 bytes T 0x4054 ARE ID CIM ID 2 bytes Data Size 2 bytes 0x0000 0x0800 Packet serial number 1 byte 0x00 0x7f 0x80 Oxff for event replies from CIM CIM Feature address 2 bytes Request Reply code2 bytes a ee gt 11 bytes minimum frame length Optional data 0 2048 bytes Optional CRC checksum 0 or 4 bytes CRC32 a ee gt 2063 bytes maximum frame length include CimProtocol h include Timer h include usb_serial h include Adc h include lt avr io h gt include lt avr interrupt h gt include lt stdlib h gt include lt stdio h gt define ARE_MINIMAL_VERSION 1 const uint32 t TEENSY_CIM_UNIQUE_NUMBER 0x050606FD uint8_t autoreply_num 0x80 const char TEENSY_CIM_FEATURELISTI 0x00 0x00 unique number data 4 bytes 0x02 0x00 Schwellwert zur Eventerzeugung setzen 47 0x03 0x00 Sendet Events 0 wenn aktueller Wert zuerst h her als der Schwellwert war und dann darunter f llt 1 wenn aktueller Wert niederiger als Schwellwert war und dann
76. with a respective driver After plugging in a new device to the host several descriptors which are data structures with a defined format define the device class and give information about the specific features to the host The first two fields of all descriptors contain the total number of bytes in the descriptor and the identification of the descriptor type Some fields of a descriptor contain references to string descriptors These are descriptors which contain information that can be displayed and are readable for humans e g in the device descriptor exist references to string descriptors describing the manufacturer the product itself and the serial number of the product 10 Descriptors Device descriptor This descriptor contains general information about the USB device and the device s entire configuration Every USB device has only one device descriptor With the device descriptor it is possible to configure the length of the descriptor itself the type of the descriptor constant that belongs to the configuration descriptor 01h the functionality of the device and the driver that has to be nominally loaded configured by three bytes DeviceClass DeviceSubClass and DeviceProtocol the maximum packet size and information about the manufacturer and the product itself For more detailed configuration options see 11 p 261 263 Table 9 8 With this information and a look at the USB class codes that are defined by the U
77. zing a commando out of a right packet the commando gets processed and an answer packet is replied If the commando that is read out of the packet is Start the trigger source of the ADC is started and therefore the sampling and all further steps are started too 41 Sending the command Stop means that the trigger source of the ADC is turned off so that no sampling takes place anyMore ee ee ee ee AR ER ee ee ee ee Re RR ee ee ee ee ee ee ee ee ee ee ee 26 Picture 15 PCB Layout for the proximity Sensor ee ee ee ee ee ee ee ee ee ee ee 30 Picture 16 Unpopulated PCB Top Layer ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee 31 Picture 17 Populated PCB Top Layer ee ee ee ee ee ee ee ee ee ee ee ee 31 Picture 18 PCB with connected mounting wires and signal wires with hot glue stabilized sensor contacts no shrinking hose ies ee Ee ee Ee Re ee ee EE Ee ee RE ee ee Re ee ee ee ee ee ee 31 Picture 19 PCB with connected mounting wires and signal wires shrinking hose over MOUNTING and signal wireS ee Rn non nn non non nennen nnnnnnennnnnnnnnnnnnnnnnn nn nenn 31 Picture 20 Box for fixing the PCB on the dedicated head mounting and protecting it against damage Box open holes for USB plug Jack Plug 3 5mm and for the mounting wire 32 Picture 21 Box for fixing the PCB on the dedicated head mounting and protecting it against damage Boxcelosed A a ee hats cacy house RE pene DE OE OE NE 32 Picture

Development of a Proximity Based Alternative Input

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