Robust computer control of an inverted pendulum

This article illustrates the design of a robust digital controller using a blend of state space and frequency response methods. The specific application is that of balancing an inverted pendulum on a moving cart while controlling the cart position. This work investigates issues regarding robust stability and disturbance attenuation. Furthermore, the effectiveness of a simple nonlinear compensation scheme for counteracting the Coulomb friction is studied. The controller design is based on an approximate discrete-time linear model of the pendulum-cart system. Design calculations and analysis are carried out using Matlab/toolboxes and M-files developed by the author.