An engineering education tool for real-time nonlinear control: Stabilization of a single link robot

Abstract

Nonlinear control is generally considered as more complex than linear control techniques by graduate students. This is especially because the analysis and design tools for linear systems comprise mature, simple and powerful methods and so almost all undergraduate programs in system engineering provide some linear control classes. But, on the other hand, all physical systems available in nature are inherently nonlinear. Graduate-level education programs in electrical engineering should provide some courses to the learner to make them able to design and implement more realistic high performance controllers to control the engineering systems. This paper deals with the experimental demonstration of the necessity of having a real-time nonlinear control system to be able to design such controllers. Specifically, the paper is designed as a supplementary experimental tool for a nonlinear control class to boost students’ interest and encouragement in this topic. For this aim, a simple tool, a single-link robot driven by a permanent magnet direct current motor, is used to demonstrate the benefits with the real-time nonlinear control systems and to provide replication facility to an instructor. The paper explains in detail the design and implementation of a nonlinear exact-model controller assuming all the system parameters are exactly known, and then, a more realistic case, a nonlinear adaptive controller with full parameter uncertainty. An additional experiment on the effects of a non-real-time system is also presented.