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Motion Tracking & Position Acquisition. Final Presentation. Solomon Gates | William K. Grefe | Jay Michael Heidbreder | Jeremy Kolpak. Overview of Project Objective. Primary Goal Achieve accurate and precise motion of laser pointer directed at a locator beacon Secondary Goal
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Motion Tracking &Position Acquisition Final Presentation Solomon Gates | William K. Grefe | Jay Michael Heidbreder | Jeremy Kolpak
Overview of Project Objective Primary Goal Achieve accurate and precise motion of laser pointer directed at a locator beacon Secondary Goal Obtain precise object position from sensor input
Original Design Specifications • Object tracking velocity: • Object velocity of 10 mph • Pan/Tilt velocity of 10 radians per second • Object acquisition within 1 second • Distance to object: ½ft – 20ft • Range of motion: • Pan range of 180° • Tilt range of 90° • Target Acquisition Accuracy • ½” at a range of 20 ft (0.0021 radians) • 1/8” at a range of 6” (.021 radians) • Tracking Moving Object • ± 1” @ 20 ft (0.004 radians) • ± ¼” @ 6” (0.041 radians)
Controller Design Process Simulate Desired Motors Simulate Plant (Linearized System) Designed PID Controllers Tested System (Real World) Designed Friction Compensation
Designing a Suitable Controller • Linearized our simulated plant system • Estimated desired dampening and natural frequency values to achieve a suitable overshoot and settling time. • Created a PID controller • Simulated the PID controller input response with the linearized plant system.
Real World Plant/Controller Testing • Initially our real world system did not react to the controller as the simulated system. • Real World friction compensation was initially non-existant (identify viscous and coulomb friction) • Simulated plant friction model was incorrect • Estimated system models were not completely accurate causing phase difference in system response
Basic Friction Compensation System • Add coulomb compensation based on the change in encoder reading • This type of compensation can fail when the motor approaches the steady state value (stiction zone) • If at this point the encoder reading does not change, the coulomb compensation is not added and the motor does not move and for future readings the encoder will not change. • Basic Friction Point to Point Video
Group 3 Friction Compensation System • Add coulomb compensation based on the difference between the current and desired position. • This will provide constant compensation until the controller acquires the desired position. • This can however cause oscillations for small movement and near the steady state value. • We fixed this by adding a dead zone to remove oscillations near steady state.
Sensor Design Beacon will be built from six ultrasonic transceivers to allow 360° range Three receivers received signal
Sensor Problems • Radio frequency transmitter and receiver pair proved too complicated to implement on ARCS system • Ultrasonic transmitter and receivers were built and tested; devices shown to communicate with each other • No time remained to integrate transmitter with PIC microcontroller and MATLAB code with enough accuracy.
Position Acquisition • Receivers built and tested to acquire a signal from the transmitter • MATLAB code used to calculate x,y,z position based upon simulated distance information from three simulated receivers • Position was then related to the given position of laser to generate angle values Da, Db, Dc x, y, z Θ1, Θ2 MATLAB Triangulation Routine MATLAB Angle Localization Routine Controller
Success & Challenges • It was challenging to relate the real world plant to the simulated model. We were able to achieve this in the end. • Creating the friction compensation was more of a challenge than we had expected, and in the end came up with a new way to handle this. This new system however, had its own drawbacks that we overcame. • Creating a sensor system from scratch. We were able to successfully create the components however time did not permit us to integrate and test them with our controller.
