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Team: Nathan Gendron, Eric Escobar, Jason Hsu, David Gervais Advisors: Richard A. Messner, Barry K. Fussell Special thanks to Richard A. Messner and Barry K. Fussell for advising our team on this project. We would also like to thank Professor May-Win Thein, Adam Perkins, and Scott Finance for their contributions and support. Introduction Ping pong is one of the most popular recreational table games in the world. However, it is best enjoyed with two people. Thus creating the question, “How can someone enjoy the game of ping pong without a partner to play with?” The solution to this problem is the Automated PongBot. The Automated PongBot is a machine developed to emulate life-like gameplay by implementing, variation, randomness and logic. Trough Receives collected ping pong balls from the center PVC pipe and distributes them to the required tower • Receives balls passed through feeder from the trough • Four 12V DC motors with 1.25” diameter hubs used to fire ping pong balls with various spins and speeds • The appropriate hub diameter was determined in MATLAB by inputting the initial height, position from the table, and the angular velocity of the motors [1] Tower • Stepper motor used to control the flow of ping pong balls released to each tower • Hall effect sensors and magnets used to determine feeder stopping position Challenges Encountered • Determining the correct range of velocities that the ping pong balls could be fired at • Creating a netting that would successfully direct ping pong balls to the return system • Precision and consistency required for driving the stepper motors • Accurately sensing the position of the ping pong balls • Supplying appropriate current levels to the DC motors • Running all devices in a timely manner off of one microcontroller [1] Matlab figure used to determine the appropriate hub diameter Sensors Infrared range finders output an analog voltage corresponding to the distance from the sensor. [2] This allowed us to determine which tower will fire next. Four sensors are used to cover a larger area on the ping pong table and give a larger time frame for sensing. 0 1 2 3 4 5 6 7 8 9 10 11 0 100 200 300 400 500 Sensor Output Vs. Time Time (seconds) Sensor Output Amplitude 1 Feet 2 Feet 2.5 Feet 3 Feet 4 Feet 5 Feet [2] Matlab figure displaying Sensor output Amplitude at various distances 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 2 4 6 8 10 12 14 16 18 20 Velocity of Ball as a function of Wheel Radius Radius of Wheel (m) Velocity of Ball (m/s) Motor Speed: 16500 RPM Motor Speed: 16500 + 5500 RPM Motor Speed: 16500 - 5500 RPM Velocity Limits (Must Remain within Limits) Collection and Return System • Netting collects balls and directs them towards return system • Return system drives the collected balls back to the trough using a stepper motor Feeder Conclusion The Automated PongBot experienced a variety of changes from its initial proposal to its final design. The motors initially used were not powerful enough to obtain desirable velocities. Larger motors were substituted which required the use of Darlington transistors to fulfill the motor’s higher demand for current. Hall effect sensors were added to the design to compensate for the natural error associated with the stepper motors. The overall objective of emulating life-like game play was achieved to an extent. The sensing system was unfortunately unable to consistently detect ping pong balls during game-like situations due to the response time of the sensors. A recommendation for the future would be to incorporate image processing to determine the ping pong ball’s trajectory.
