Servomechanisms with Computed Torque Feedback

Abstract

The computed torque feedback method is presented as a compensating technique for servomechanisms. In this method, the servomotor torque, not detected through a torque transducer but computed from both the manipulated variable and the output speed, works for a local feedback signal in a servomechanism. The servomechanism applying this method becomes nonlinear, and is analyzed by the phase plane technique. The servomechanism with torque or computed torque feedback shows similar characteristics to the relay servomechanism with nonlinear velocity feedback, and can be designed to have an optimum response for a fixed load like optimum nonlinear control, but the response becomes oscillatory or overdamped as the load inertia increases or decreases. The computed torque feedback method is applied to a direct current servomechanism, and the feasibility of this method is confirmed through an experimental study.