A switched control strategy for swing-up and state regulation for the rotary inverted pendulum

The rotary inverted pendulum (RIP) is an underactuated mechanical system that can be balanced in the upward position, by applying the linear control theory based on a nonlinear dynamical model linearized around that position. Its structure makes it possible to implement controllers designed for energy minimization in the non-linearizable region. Due to the limited validity of the resulting linear model, a nonlinear control is needed to automatically move the pendulum close to the linearized region, starting from its stable downward position. A RIP platform has been built to experimentally test a switched control strategy design, which combines an energy-based nonlinear controller for swinging up the pendulum and a linear quadratic regulator for the balancing task. Experimental results validate the performance of this approach on the physical prototype.