Ball & beam experiment control with current sensing

Abstract

One of the most typical experiments in control is the classical Ball & Beam apparatus. An electrical measurement of the ball position is traditionally used to perform control. The metallic ball makes an electrical contact across the two Cr-Ni rails in which it circulates. The current injected in one of the rails creates a measurable voltage difference between the terminals of the second one, linearly dependent with the ball position. The measurement noise is filtered out using both analog and digital techniques. By also measuring the beam tilt angle with a digital protractor, the system becomes observable. Using two cascaded digital PID controllers the position of the ball is kept around the set point with a standard deviation of 10mm. The experiment performs correctly allowing deep study of the noise influence on the controller and its mitigation techniques. The control board is connectable to a single-board computer enabling remote operation of the experiment. Integration on a remote control laboratory such as e-lab is straight forward.