Robust control of self-balancing two-wheeled robot

Abstract

This chapter presents the design and experimentation of a 2-degree-of-freedom robust controller for a self-balancing two-wheeled LEGO® Mindstorms NXT robot. A 12th order discrete-time controller is designed by using the techniques of μ-synthesis. The closed-loop control system achieves robust stability and robust performance in the presence of two uncertain friction coefficients. Since the robust controllers are of higher order the basic problem is to check the possibility to implement such controllers on the available microcontroller working with sampling frequency fs=250 Hz in the stabilization loop. The results obtained show that the microcontroller under consideration implements without difficulties the discrete controller designed that allows to improve the closed-loop system performance. Results from the simulation of the closed-loop system as well as experimental results obtained during the real implementation of the controller designed are given. The experimental results show that the robot preserves stability in the vertical plane for deviations greater than 16°.