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Transcript
Whitewater Kayak Slalom Race Timer Engineers: Kevin Lockwood Chris Munshaw Ashley Penna John So Project Funded By: Mike Neckar Founder, Necky Kayaks www.necky.com Background on Whitewater Kayaking • Whitewater kayak slalom racing began shortly before World War II • This Olympic sport involves racers paddling down a natural or man-made rive • Kayakers must maneuver through hanging pairs of gates. • Judges at shoreline determine correct maneuvering through gates. Background on Whitewater Kayaking C1 (Canoe) on a man-made course Background on Whitewater Kayaking K1 (Kayak) on a natural river course Kayak Rules • The racer must proceed through green gates in the down-river direction • Red gates in the up-river direction • 2sec penalty for touch gates but going through • 50sec penalty for touch and not gone through Present Situation • Judge watching at each gate to make sure the kayaker goes though • Judge determining if each gate has been touched • Stop-watches used in training for timing • Obvious problems: Human error, biases, judges not omniscient Our Solution Create a automated system which tracks a kayaker’s progress through a race course and determines if gates are touched. Focus on creating a reliable and low cost product. Offset the cost of using humans to judge gates. Secondary goal is timing accuracy. Marketing • Mr. Neckar - use for training by olympic athletes - introduced in races such as national team trials (Vedder River, Chilliwack) • Scott Shipley, US national team member - promotion in the United States Timeline Overall, we are behind the proposed schedule by about two weeks. Our Proposed Timeline 1-Jan-07 Research Proposal Functional Specification Design Specification Assembly of M odules Integration/Prototype Testing Debugging/Prototype M odification Documentation Progress Report 16-Jan-07 31-Jan-07 15-Feb-07 2-M ar-07 17-M ar-07 1-Apr-07 16-Apr-07 Delays are caused by… • Waiting for sensors, microcontrollers, and RF modules to arrive. • Testing other design options. • Errors and bugs • Underestimated Integration Time • Earlier than expected deadline Timeline The Actual Timeline System Overview How to detect a Kayaker? Ultrasonic beam across the gates RF tag triangulation IR beam across the gates Ultrasonic Beam Advantages not affected by environment low noise low power consumption Disadvantages wide beam difficult to integrate multiple ultrasonic sensors due to coupled interference RF Tag Advantages Very hard to cheat the technology Low power Disadvantages Difficult technology to use Requires a high computational load to calculate location Can be expensive Optical Beam (Our Solution) Advantages Narrow beam Easy to implement Unaffected by environment Lower costs Disadvantages Consumes higher power the ultrasonic Sensitive to alignment IR LED vs. Laser • Laser (Visible Spectrum) 650nm - coupled with a photodetector + amplifier - very high signal strength at large distances (5m +) - very narrow viewing angle - low power consumption (~20mA) - class III and above can cause retinal damage IR LED vs. Laser • IR LED 950nm - coupled with an NPN phototransistor - very low signal strength at distances over 2m (required amplification) - wide viewing angle (35°) minimizing problem of gate flexibility - high power consumption (~100mA) - cannot cause retinal damage IR LED: Improving Signal Quality • Ambient light shielding - used a non-reflective black paint to coat a drinking straw (this also formed a watertight seal over the phototransistor) • Modulation - modulated the IR emitter with a 2kHz square wave - demodulating at the receiving side would filter out noise cause by reflections of sunlight off water, etc IR LED: Improving Signal Quality • Ambient light shielding - used a non-reflective black paint to coat a drinking straw (this also formed a watertight seal over the phototransistor) • Modulation - modulated the IR emitter with a 2kHz square wave - demodulating at the receiving side would filter out noise cause by reflections of sunlight off water, etc IR LED: Overall System • Amplification -> Filtering -> Thresholding - Amplification boosts the output signal strength - Filtering creates a steady signal representing the amount of IR light detected - Thresholding creates a digital signal representing whether or not the line of sight is considered “broken” IR LED: Modulation • Decreased average current consumption from 180mA overall to 110mA overall. • Waveform created using an astable 555 timer Simulation on breadboard IR LED: Demodulation • Filtered using an LRC circuit, tuned to 2kHz IR LED: Final Signal Accelerometer • Used to detect any contact with the gate • 3 axis, ±5g output range • Mounted 1 accelerometer per gate, in the lower region of the gate (added sensitivity) Accelerometer: Signal Conditioning • Low Pass Filter: allows us to “dull” the signal and remove unwanted noise • Comparator: gives a digital signal representing whether or not the acceleration of the gate is beyond an acceptable level -> this allows us to have the system ignore low acceleration conditions such as gates swaying in the wind Accelerometer Performance Tests • Comparator Threshold = 1.665V (red line in graph) Future Improvements on Signal Conditioning • Have circuits printed on PCB • Use only variable resistors reference voltages in comparators • Improve demodulation circuit, possibly using an active filter Final Sensor Signals • Two digital signals representing the clearance of a gate, and contact with a gate (both fully adjustable) • However, current consumption is becoming high (approx. 180mA) • This leads us to attempt ‘Presence Detection’ Presence Detection • Used to detect the presence of an approaching kayaker. • Used to trigger the turn on high power consuming subsystem. • Used Ultrasonic sensors • Accuracy • Immunity • Ease Presence Detection The sensors have an analog output proportional to the distance of an object. Used thresholding to detect object presence Used timing circuit to filter noise. Presense Detection Future Upgrades • Currently we do not have a way to detect which direction the kayaker came from. • Gates are direction dependant according to whitewater kayak Rules. • We will switch to IR presence detection, due to better immunity to environment. • Will use one facing each direction in gate to determine direction of approach. Data Communication Requirements • Reliable • Long Range • Low Power • Fast Transmission Data Communication Solution ZigBee Xbee Module from Maxstream 30m range (upgrade 1mile) Current Consumption during Transmission 45mA UART Communication Format easy to integrate with our Micro Controller Data Communication Future Updates • We can upgrade to Xbee Pro modules for an increased range. • Requires more power. • Allow software to communication back to gates. • Remote reconfiguration • Remote turn on/off MicroController Firmware • Requirements – Very little memory needed – Simple program – USART Register for RF Modules – A/D Conversion capabilities – At least 3 inputs (IR Sensors, Ultrasonic, Accelerometer) MicroController Firmware • Main Jobs – Get a development environment running – Integration with ultrasonic to turn on power board – Integration with IR sensors – Integration with RF modules MicroController Firmware • Multiple Development Environments • 1) PICDEM – 1st to work MicroController Firmware • Good Features – Easy viewing of ports – Attached LEDs to eliminate the need to probe – Multiple ways to power – MPLab compatibility • Problematic Features – Had to replace 40pin socket – Initial running of programs – Quantity MicroController Firmware • Multiple Development Environments • 2) OUMEX – 2nd to work MicroController Firmware • Good Features – One LED to map outputs of interest to – Programming capabilities using MPLab – Less reliance on development board • Problematic Features – Building a cable from MPLab to ICSP – Initial running of programs – Quantity – shipping time MicroController Firmware • Multiple Development Environments • 3) Prototype – Last and finally!!! MicroController Firmware • Good Features – Cheap – Space saving – Easy connection to other circuits • Problematic Features – Must move to another development board to program – Determining which components were necessary MicroController Firmware • IR Flag gets set in an interrupt • Accelerometer Flag gets set in an interrupt MicroController Firmware • Ultrasonic Powering Sensor Circuit – Creates an interrupt which sets a flag – Main program deals with this – Output will be high when ultrasonic is high • IR sensors Circuit – Creates an interrupt which sets a flag – In main program, transmission showing the gate number and IR occurs MicroController Firmware • Future Improvements – Automatic Gate Addressing – Sleep pins on the RF module – Polling gates for possible battery voltage The Power IR sensors consume around 150mA. Portable/Inexpensive power source in a 9v battery Provide clean power at 3v and 5v for all subsystems. Supply should last for 8hrs of use Power Solution Isolated control directly from Micro Controller. Micro Controller uses the low power Ultra Sonic sensors to trigger IR sensor circuit. Circuit Board contains controlled outputs at 3v and 5v for high power, and continuous outputs of 3v and 5v. Power Solution We want our portable power supplies to last 8 hours of continuous usage System Power Consumption Before Power Control • Total Power Required = 1.21Ahr System Power Consumption After Power Control • Total Power Required = 0.511Ahr Power Solution Without a controlled power supply for 8hrs of continuous use requires 1.21Ahr With a controlled power supply for 8hrs Of continuous use requires 0.511Ahr Saves nearly 250% of our AmpHours required. Improves portable power supply options. Power Solution We use two Rayovac 9v Alkaline batteries in parallel for each gate Batteries spec at -30C to 55C Each Battery has approx. 0.5Ahr Graphical User Interface Graphical User Interface • Purpose: – Allows user to set up a race quickly. – Communicates with the RF module and collects data from gates. – Displays data in table form. – Automatically times the race and applies penalties. Graphical User Interface • Functions: – Kayaker list management. Add and remove kayakers. – Modify number of gates. – File I/O – Display data: • Names • Race Time • Penalties applied to each gate Graphical User Interface • Program flow 1. User adds the names of kayakers in order. 2. User determines the number of gates. 3. User modifies the serial port settings. • Step 1, 2 and 3 are interchangeable. 4. User presses ‘Begin’ button to begin the race. Name list and gate number cannot be modified from this point onwards. Graphical User Interface • Program flow (continued) 5. Program reads and displays data automatically. - Decodes gate messages sent through RF module - Applies 2 sec time penalty if gate touched. - Applies 50 sec time penalty if gate missed. 6. Calculate race time and add penalties to it. 7. Table may be exported in .txt format and uploaded to MS Excel. Graphical User Interface • Problems encountered: – Exception handling – Symbol error due to baud rate mismatch – Repeated messages from gates – Timing delay Graphical User Interface • Future Improvements: – Time delay calculation – Support multiple kayakers on the course – Name list sorting – Automatic available port detection Summary Created a automated system which tracks a kayaker’s progress through a race course and determines if gates are touched. Focus on creating a reliable and low cost product. Offset the cost of using humans to judge gates. Increased timing accuracy The End • Questions? Appendix: Signal Conditioning Appendix: Modulation • Emitter: (Breadboard) Appendix: Modulation • Receiver, modulated: (Breadboard) Appendix: Demodulation • RLC Bandpass Filter sCR • H(s)= 2 s CL sCR 1 • Using R=1, C=6.33uF, L=1mH Appendix: Demodulation Appendix: Demodulation • Receiver, de-modulated: (Breadboard) Appendix: UltraSonic Circuit • Used a simple LM324 OpAmp with a threshold voltage. Threshold set to approx. 5.5ft. • 555 Monostable Timing circuit holds detection high for 5sec. This filters the natural circuit noise from the ultrasonic sensor. Appendix: Ultrasonic Circuit Appendix: Power Requirments Before Power Control Continuous Power Consumption • 110mA (IR circuit) + 15mA (Ultrasonic) + 25mA (Micro) = 150mA RF Consumption • (150 trans. approx.@ 0.5 sec/trans) = 0.9mA Total Power Required = 1.21Ahr After Power Control Continuous Consumption 15mA (Ultrasonic) + 25mA (Micro) = 40mA IR Consumption 110mA (150 passes. approx.@ 5 sec/pass) =23mA RF Consumption 45mA (150 trans. approx.@ 0.5 sec/trans) =0.9mA Total Power Required = 0.511Ahr Appendix: Power Circuit Appendix: Power Circuit Lag (4ms) Appendix: Transmission Appendix: Transmission Appendix: Transmission Time