Teaching Nonlinear Control by Means of a Ball on the Wheel System

A comprehensive education in control engineering naturally includes nonlinear control theory. Understanding the associated methods is a great challenge for many students due to the required theoretical background and the often-missing applicability of the methods to real-world problems. The proposed paper deals with how this problem can be addressed using a specially developed practical experiment, a so-called Ball on Wheel (BOW) system. An EC motor exerts the necessary torque on a vertical wheel to control the trajectory of a ball lying loosely on it’s contour. Different controllers were developed using the nonlinear control theory of full state linearisation. In addition, the BOW system offers various operating modes by applying individual reference trajectories to the linearised state space. Using the BOW laboratory model, both the challenges and the advantages of the mechanical design and the implemented controls are examined. This approach provides students with the practical and understandable meaning and necessity of nonlinear control theory.