August 2010: This is my new touch screen Arduino-based Ball and Plate system, the evolution of my old system shown here. The controller used here is Arduino, the position sensor is not a camera anymore, but a resistive touch screen sensing the ball on its surface. The plate is actuated in the pitch and roll axes by two RC servos, adapted to be mounted in the LEGO Technic System. Click here for details about the servo attachment, click here.
The program controls the ball to track some predefined paths, or keeps it balanced in the center. Two decoupled PID loops control the pitch and roll axes. A simple Kalman filter is used to estimate the ball speed.