Design and implementation of force and position control with anti-windup conditioned transfer compensation

This paper investigates the design and implementation of a force and position servo control system where non-linearities are encountered due to constraint on the torque signal to the motor drive, and switching between position and force controllers. The so-called two-step design paradigm is employed, whereby the velocity, position and force controllers are designed first ignoring control input non-linearities, and then anti-windup and conditioned transfer compensators are added using the Hanus conditioning technique. Both linear position and force controllers are designed using the H∞ loop shaping design procedure, and the H∞ controllers are found such that the Hanus conditioning technique for anti-windup conditioned transfer compensation can be applied. The overall controller is derived and presented in the state space framework, and its performance is evaluated in real time on an experimental set-up using a commercial digital signal processor.