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Automated Ball Striker. Joseph Black David Caloccia Gina Rophael Paul Savickas. Presentation Outline. Motivation Objective Specifications Design Approach Results Assessment Conclusion . Motivation.
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Automated Ball Striker Joseph Black David Caloccia Gina Rophael Paul Savickas
Presentation Outline • Motivation • Objective • Specifications • Design Approach • Results • Assessment • Conclusion
Motivation • Extension of the Ping Pong Shooter from Team 2 of Spring 2005 • Inspiration: to develop training equipment for ping pong players.
Objectives To strike a vertically launched ping pong ball. • Launch a ping pong vertically at various heights • Visually locate the launched ping pong ball • Process data to determine ball’s position and velocity • Develop trajectory for paddle’s motion • Design a controller to track the desired path
Specifications Step response: • Steady State Error 0.195% • Percent Undershoot 12.58% • Rise Time 0.43 s • Settling Time 1.43 s Other Specifications: • Range of Motion (Pan) -80°to +100° • Range of Motion (Tilt) 0°to +90° • Payload 200 grams • Noise Tolerance 95% • Weight of the System is ~1Kg • Commercial Cost $2462.75 • Speed is 8rad/sec for pan and for tilt 10rad/sec • Images processing rate 30 frames/second • Sampling time for the controller 10 micro sec
Design Approach • Modeling • Control Design • Launcher • Vision • Physics Model • Trajectory Generation • Integration
Modeling • General Equation of Motion • Disconnect between model and system • A simpler model was pursued
Modeling • Simplified Equation of Motion • Steady State • Friction Identification • Transient Response • Inertia
Friction Identification Viscous Friction = .0087 NmS/rad Coulomb Friction = .0141 Nm
Model Validation • Open loop response
Model Validation • Closed loop response • Differences between model and system • The final model was useful in understanding the system, but control design was done on the actual system.
Control Design • Control applied using the FPGA PID block in LabVIEW. • The PID for set point control with sampling of 100 microseconds, 512 proportional for pan and tilt , 3/128 integration for pan and 1/128 for tilt. • Swing controller pan 10 microsecond sampling, proportional 1792 , derivative 7/128, derivative control may not have much affect with such a high sampling rate.
Launcher • Final Design • Ball Support • Multiple Balls • Performance • Launch Height • Verticality
Vision • Collect frames at 30 frames per second, threshold the individual images and filter out small objects, to remove dust and the black balls reflecting light back to camera. • Check for ball in frame, first time records the position and time of image after 2nd image of ball subtracts position and time from previous image to determine velocity
Vision • Used LabVIEW Vision Assistant to make calibration information image from a image of a dot matrix in the plane of the launch, with black dots at a known distance from each other fed to LabVIEW.
Physics Model • Ball Motion • 1D Motion • Initial Velocity • Position/Time Calculations • Air Resistance • Time Until Swing
Trajectory Generation • The choice of start and end positions • Development in Trajectory • Ability to choose between trajectories
Integration • Physical Integration • Base, Launcher, Webcam, Pan-Tilt • Software (LabVIEW) • Physics Model • Image Processing
Integration • A laptop is used as a host to connect to the web cam and retrieve images of the ball and calculate position, velocity and time to swing information from physics model. • Laptop communicates to begin the swing to the CRIO using VI Server, breaking the CRIO out of a set point loop into the swing signal loop. • The CRIO was used as a Real Time system to control the FPGA and to send the swing path and set points to FPGA at 1 kHz. The FPGA is used for control of the system and monitoring the position and velocity
Integration • Testing • Subsystem • Overall System • Uncertainty • Launcher • Physics Model • Swing Time • Strike Zone
Results • Probability of successful striking • Demonstration Video
Assessment • Ball Launching • Inconsistent launch • Vision/Physics Model • Reliable for successful launches • Trajectory Generation and Tracking • Accurate tracking of trajectory • Overall Success
Conclusion • Recommendations for improvement • Improvements to launcher would greatly benefit the rest of the system • Ability to aim ball toward target zones • State-space control