Saturday, August 23, 2014

Stewart Platform Ball Bearing Balancer



A couple guys at San Jose State University, as a precursor to a racing motion simulator, have built a Stewart platform. This is a special type of robot that allows motion control in all 6 axes: linear motion laterally, longitudinally and vertically, as well as rotation in roll, pitch, and yaw. In the video you see a flat table with a resistive touch screen (to determine the current location of the ball) brings on memories of the Classic Nintendo game Marble Madness

This small demonstration displays two disciplines of classical mechanics, control theory and kinematics. Control theory is a sub-discipline of dynamics that applies to many aspects of everyday life. Thermostat/HVAC systems, cruise control, and any application where a feedback sensor of some sort is used to determine the next behavior of a control on the overall system are all examples. In the case of this Stewart platform, the resistive touch screen is sharing its information with an Arduino, which then calculates the proper position of the six servo arms to maintain the balls position. Kinematics (a sibling to dynamics) is used to solve for the positioning of the servo arms.

More information on this this particular setup on Hack-A-Day and Full Motion Dynamics!