Nonlinear feedforward and feedback tracking control with input constraints solving the pendubot swing-up problem

Authors:	Graichen Knut, Universitaet Stuttgart, Germany Zeitz Michael, Universitaet Stuttgart, Germany
Topic:	2.3 Non-Linear Control Systems
Session:	Inverted Pendulum Control
Keywords:	Two-degree-of-freedom control, nonlinear system inversion, internal dynamics, non-minimum phase, boundary value problem

Abstract

The swing-up maneuver of a pendubot is accomplished by a tracking control with separate design of a nonlinear feedforward and a linear feedback part. The inversion-based feedforward control treats the swing-up as a nonlinear two-point boundary value problem with input constraints in the coordinates of the input-output normal form and is numerically computed by a standard Matlab function. The feedback part with time-variant gains is designed as an LQR controller for the pendubot model linearized along the nominal trajectories. The tracking control is validated in experimental swing-up maneuvers of the pendubot.