Anti-windup for Euler-Lagrange Plants

This chapter considers a specific case study where the model recovery anti-windup (MRAW) framework is applied to a class of nonlinear plants consisting of all fully actuated Euler-Lagrange systems. For such plants, an anti-windup construction is proposed that is capable of recovering global asymptotic stability of the closed loop with saturation as long as the unconstrained controller guarantees global asymptotic stability and local exponential stability of the unconstrained closed loop. The chapter first explains how MRAW for the saturated closed loop can be performed by generalizing the compensation scheme for linear plants, highlighting the selection of the stabilizer as a key aspect of successful anti-windup augmentation. It then presents some simulation examples to demonstrate the proposed anti-windup construction, including its application to a simple nonlinear robot arm and to models of two industrial robots, the PUMA robot and the SCARA robot.