RO326PN2 RoboBallj FlyEye Sensor RCX/NXT Operating Instructions
Contents
1. plugged into the appropriate RCX input Section 2 0 will check correct orientation of block on RCX for polarity purposes 1 4 The photodiode detectors are mounted on the underside of the PCB for a reason the overhang of the PCB helps shield them from the effects of intense overhead lights that could confuse the RoboBall FlyEye So make sure you have it the right way up Mount the RoboBall FlyEye s PCB horizontally at about the mid height of the RoboBall There is some advantage to mounting the RoboBall FlyEye higher and tilting it down a little as this can reduce the sensitivity to light sources outside the soccer field The vertical field of view extends 20 above the plane of the PCB at 50 sensitivity which means a bright infra red light source low in the background can be detected sunlight coming through distant windows is a particular problem Fluorescent lighting contains little infra red light and will have less effect than incandescent lights or sunlight If you are careful you might choose to bend all the photodiodes away from WILTRONICS RESEARCH PTY LTD PO Box 4043 Alfredton 3350 AUSTRALIA Ph 61 3 5334 2513 Fax 61 3 5334 1845 http www wiltronics com au ESEARCH PTY LTD Se RONI RO326PN2 RoboBall FlyEye Sensor RCX NXT Operating Instructions RO326PN2 DC2V1 RCX NXT operating instructions doc the PCB slightly as an alternative to tilting the PCB The 4 holes in the PCB see Fig 2 can2. straight ahead and a value of 520 is far right The highest nine values 565 925 are used to indicate the intensity of the light seen by the brightest photodiode See the adjustments section for more information on the intensity values A puk Saute S Mw EERTE ETN aA epee ee pee il pI Fig 2 The RoboBall FlyEye switches between indicating direction and intensity about ten times per second when the light source is steady However if the direction to the brightest light changes then the RoboBall FlyEye gives priority to direction WILTRONICS RESEARCH PTY LTD PO Box 4043 Alfredton 3350 AUSTRALIA Ph 61 3 5334 2513 Fax 61 3 5334 1845 http www wiltronics com au RO326PN2 RoboBall FlyEye Sensor RCX NXT Operating Instructions RO326PN2 DC2V1 RCX NXT operating instructions doc information and will output the new direction value immediately and in preference to a new intensity value Having said that an intensity value will always be output at least 5 times a second See the programming section for more information on how to use the values read from the RoboBall FlyEye 3 2 Note that when you use the view button to look at the output of the RoboBall FlyEye the RCX refreshes the display quite slowly so that you will not see the RoboBall FlyEye values change 10 times per second However a properly written program will have no trouble reading these rapid changes 4 Adjustments 4 1
3. slight variation between devices 2 4 After the initial power on test the displayed values will start to change depending on what the RoboBall FlyEye sees Remember that the RoboBall FlyEye goes through its self test every time it is turned on so make sure that you have your robot turned on at least a few seconds before you need to run your soccer program 3 Understanding how it works 3 1 There are seven photodiodes see Fig 3 on the underside of the RoboBall FlyEye and these look in different directions A microcontroller built into the RoboBall FlyEye compares the light intensity seen by each of the seven photodiodes and picks the brightest one The RoboBall FlyEye can send 16 different voltage levels to your robot On an RCX port in raw mode these correspond roughly to values starting at 250 and increasing in steps of 45 i e 250 295 340 385 430 475 520 565 610 655 700 745 790 835 880 amp 925 See the 3 wire interface section for the actual voltage levels Note these values are approximate and will depend on the exact setting of VR1 see the adjustments section there will also be some variation in the values during normal operation and your program must be written to deal with this The lowest 7 values 250 520 are used to indicate which photodiode is seeing the brightest light So a value of 250 indicates the brightest light is seen by the far left photodiode a value of 385 indicates
4. that some multimeters will not read the output correctly as it switches rapidly between the different output voltages Page 4 of 4 7 Other things to think about You ll notice that the photodiodes are spaced closer together towards the forward direction Arranging the photodiodes this way gives your robot the most precise information about changes in ball location where it needs it most just like a human eye which perceives more detail in the centre of vision with only vague detail on the periphery The field of view of the individual photodiodes is wide enough that they overlap their neighbour s field of view So there are no gaps in the RoboBall FlyEye s vision The most obvious way to make use of the RoboBall FlyEye output is to have your robot turn until the ball is straight ahead and then go forward If the ball moves to one side or the other your robot can correct its direction while still giving chase But you can also have your robot turn until the ball is in front of one of the other photodiodes With a slight change of programming you can have your robot hit the ball from the left or right or even circle around it Experiment and have fun RCX port RAW mode Output Voltage 122V _ Table 1 RoboBall FlyEye Sensor Design amp Specifications Copyright Wiltronics Research Pty Ltd amp IME Consulting Solutions Pty Ltd 2005 Australian Innovation Patent No 2005100750 Robo
5. Ball is a Trademark of Wiltronics Research Pty Ltd LEGO LEGO MINDSTORM RCX amp NXT are registered Trade Marks amp Trade Marks of the LEGO GROUP OF COMPANIES Robolab is a registered Trade Mark of Tuft s University ROBOCUP JUNIOR is a Registered name of the ROBOCUP FEDERATION DESIGNED AND MANUFACTURED IN AUSTRALIA WILTRONICS RESEARCH PTY LTD PO Box 4043 Alfredton 3350 AUSTRALIA Ph 61 3 5334 2513 Fax 61 3 5334 1845 http www wiltronics com au ESEARCH PTY LTD Se RONI
6. RO326PN2 RoboBall FlyEye Sensor RCX NXT RO326PN2 DC2V1 RCX NXT operating instructions doc The RoboBall FlyEye Sensor has been designed to be used with pre programmed robots competing in the RoboCup Junior competitions The RoboBall FlyEye Sensor was born out of practical experience with the most common and frustrating problem encountered in constructing a soccer robot reliably finding the ball Features of the RoboBall FlyEye Sensor e Designed to work directly with LEGO RCX NXT e 16 output levels relative to the ball direction and distance from ball intensity Mechanical Specifications Fig 1 e Dimensions 0 5mm e Weight 65g e Powered from NXT see section 1 2 RCX see section 1 3 1 Installation Instructions 1 1 The RoboBall FlyEye Sensor may simply be connected to your standard LEGO MINDSTORM RCX NXT interface with no modification to the RoboBall FlyEye Sensor gt Connecting to the NXT 1 2 You will need a LEGO NXT extension lead Cut the lead in half or to a desired length and then separate the White and Black wires in the NXT lead stripping the insulation on these to bare 3 5mm of copper The other four wires are not required they should be cut off carefully so the centre copper conductors can not touch together Operating Instructions Page 1 of 4 LATCH UNDERNEATH ER WHITE ee BLACK LEGO NXT lead Slide on 15mm of 5mm heatshr
7. There are two adjustments available on the RoboBall FlyEye set by VR1 amp VR2 shown in Fig 1 amp Fig 2 These are pre set at manufacture and should not need altering but if you do 4 2 VR1 adjusts the digital output levels To set this locate the RoboBall FlyEye so that the far left photodiode is facing a very bright light and the output switches between the minimum and maximum values 250 and 925 realistically 275 and 900 Rotate VR1 to adjust the range 4 3 VR2 adjusts the optical scale The RoboBall FlyEye senses light on a logarithmic scale That means that light levels corresponding to successive output values differ by the same factor This is similar to how a human eye perceives intensity and means that the RoboBall FlyEye can indicate intensities ranging from bright sunlight to a dimly lit room on one scale The best guide to adjusting the optical intensity covered by the scale is to put the soccer ball as close as it will get to the RoboBall FlyEye and adjust VR2 until the intensity just registers at the top of the scale i e a Max reading of about 920 875 925 5 Programming 5 1 This section is for RCX based robots but you can use it as a general guide for other platforms The first step is to configure the input port to be a powered sensor like a light sensor The RCX reads all sensors on a range O to 1023 but then applies a conversion depending on what type of sensor is being use
8. ab make sure that you read the RoboBall FlyEye value into a container and then use the stored value to do related calculations or branches in your program The value read from the port can change at any time and there is no guarantee that two successive reads from the port will return the same value no matter how close together they are in your program Because the RoboBall FlyEye can switch its output ten or more times a second you need to arrange that your program calls the reading function SubVI at least 20 times a second if it is not to miss an important change in direction the ball can move a surprising distance in a tenth of a second You might WILTRONICS RESEARCH PTY LTD PO Box 4043 Alfredton 3350 AUSTRALIA Ph 61 3 5334 2513 Fax 61 3 5334 1845 http www wiltronics com au RO326PN2 RoboBall FlyEye Sensor RCX NXT Operating Instructions RO326PN2 DC2V1 RCX NXT operating instructions doc consider using a separate task to read the RoboBall FlyEye so that the values are always kept up to date This simplifies the programming but be aware that the RCX multi tasking sometimes creates unexpected problems when your robot needs fast reactions VE Fig 3 6 More testing By now you probably know that the secret to good robotics is test test and test again So once you have the RoboBall FlyEye plugged in and have observed the initial power on test and understood what the output values mean perfor
9. be used to assist with mounting the RoboBall FlyEye Sensor to your robot however due to slight hole size and hole to hole distance variations in the PCB manufacturing process we do not recommend that these hole be used for power connections as they may prove to be unreliable 1 5 The light emitted by a RoboBall can vary depending on whether one of the LEDs is facing you or not So make sure that when you mount the RoboBall FlyEye that the plane of maximum sensitivity is directed towards the centre of the ball when it is close up that gives it the best chance of catching the output from at least one of the RoboBall LEDs as the ball rotates 1 6 The RoboBall FlyEye Sensor should now be ready to use _ gt 2 NXT Software Firmware Compatibility The new NXT allows for compatibility with the old RCX sensors however you will need to download the appropriate software 2 1 If you are using NXT you will need to update the software programs running in your NXT go to the website http mindstorms leqgo com Support Updates There you will find a number of programs you will need to load your NXT with LEGO MINDSTORMS NXT Firmware v1 04 Dynamic Block Update and Legacy Block Library 2 2 f you are using a RCX you will then need to write a small RCX program to configure one of the input ports as a powered sensor and then change the sensor to raw mode See the programming section if you are not sur
10. d The conversions used for the various Lego sensors do not make much sense for a RoboBall FlyEye so the next step is to tell the RCX that we want the raw readings If you are using NQC and have the RoboBall FlyEye on Port 1 then the two commands to use are SetSensor SENSOR_1 SENSOR_LIGHT SetSensorMode SENSOR_1 SENSOR_MODE RAW Page 3 of 4 If you are using Robolab then use the Powered Sensor Container VI to store the RoboBall FlyEye reading in a container In the example below the RoboBall FlyEye would be plugged into port 1 5 2 To simplify the logic and to round off the effects of small variations in the RoboBall FlyEye output it is a good idea to convert the raw values into something easier to interpret The following NQC function shows one way you might do this int Direction int Intensity void Read FlyEye int Temp Temp SENSOR_1 230 45 if Temp lt 7 Direction Temp else Intensity Temp 7 In this example values up to 274 will be converted to Direction 0 between 275 and 319 converts to Direction 1 and so on The nominal output levels of the RoboBall FlyEye 250 295 etc will fall in the middle of these ranges and give the best immunity to any noise on the output 5 3 In Robolab you can do a similar conversion using a Formula Container VI to do calculations with the number stored by the Powered Sensor Container VI Whether you use NQC or Robol
11. e how to do this Download the program and run it Press the view button on the RCX to view the port you have just configured With nothing plugged into the port the display should read 1023 if it does not then check your program If you plug a standard Lego light sensor into the port then the red LED on the sensor should light up again if this doesn t happen check the port configuration before proceeding 2 3 Now plug the RoboBall FlyEye into the port that you just configured and double check that the display is still viewing that port Unlike Lego light sensors the RoboBall FlyEye will only operate correctly if it is plugged into the RCX port the correct way round Dont worry the RoboBall FlyEye is protected against the reverse polarity that occurs when it is plugged in the wrong way If you see a constant number around 630 displayed then you need to reverse the connector When you plug the RoboBall FlyEye in the right way round it will go through an initial power on test which will result in a sequence of readings starting at around 925 After about 1 second the displayed value should decrease over a period of about Page 2 of 4 1 5 seconds until a number around 250 is displayed for a further 1 second If you see this sequence of numbers then your RoboBall FlyEye is working properly and you have connected it correctly Don t worry if the numbers are not exactly 925 or 250 etc there is always some
12. ink tubing over full cable slide 10mm of 2 5mm heatshrink over both wires then 10mm of 1 5mm heatshrink tubing over the individual White and Black RoboBall FlyEye wires Twist and solder striped Black NXT wire to the Black RoboBall FlyEye wire then twist and solder striped White NXT wire to the White RoboBall FlyEye wire Slide the 1 5mm_ heatshrink over the joints and carefully heat the heatshrink to insulate the terminations avoid heating larger heatshrink The larger sections of heatshrink can be slid over both and carefully heated this gives isolation and strain relief Now the LEGO cable can be plugged into the appropriate NXT input gt Connecting to the RCX 1 3 You will need a LEGO RCX extension lead Cut the lead in half or to a desired length and then strip the insulation from the two black wires baring 3 5mm of conductor Slide 10mm of 2 5mm heatshrink over both wires then 10mm of 1 5mm heatshrink tubing over the individual White and Black RoboBall FlyEye wires Twist and solder a striped Black RCX wire to the Black RoboBall FlyEye wire then twist and solder other striped Black RCX wire to the White RoboBall FlyEye wire slide the 1 5mm heatshrink over the joints and carefully heat the heatshrink to insulate the terminations avoid heating larger heatshrink The larger section of heatshrink can be slid over both and carefully heated this gives isolation and strain relief Now the LEGO cable can be
13. m the following simple test to demonstrate the RoboBall FlyEye s operation You need a single bright light a desk lamp or torch for example in an otherwise dimly lit room Make sure the RCX has run a program to set the input port correctly and cycle the RCX display to the RoboBall FlyEye port with the view button Turn the light on and position the RoboBall FlyEye so that the far left photodiode looking from the top of the board is facing the light Watch the RCX display you should see it change between a number near 250 and a number higher than 600 A very bright light like a quartz halogen desk lamp should read a value near 900 at close range Slowly rotate the RoboBall FlyEye or move the light so that each of the other photodiodes faces the light in turn The display should alternate between the higher intensity value and a different lower value depending on which photodiode faces the light When the bright light is straight ahead the lower value should be about 385 and when it is to the far right about 520 Again some variation in these values is normal and the values may be changed by the setting of VR1 Now change the intensity either by moving away from the light or by shading some of the light near the source you should now see the intensity value the higher number that is displayed decrease If you re not using an RCX then you can view the RoboBall FlyEye output with a digital multimeter but be aware
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