Modeling, Analysis, and Control of Mechanical Systems under Power Constraints

Abstract: Significant improvements have been achieved in motion control systems with the availability of high speed power switches and microcomputers on the market. Even though motor drivers are able to provide high torque control bandwidth under nominal conditions, they suffer from various physical constraints which degrade both output amplitude and bandwidth of torque control loop. In this context, peak power limit of a power source, as one of those constraints, has not been fully explored from the control perspective so far. A conventional and practical way of considering peak power limit in control systems is to model it as a trivial torque saturation derived from the allowable torque at maximum speed satisfying the constraint. However, this model is overly conservative leading to poor closed loop performance when actuators operate below their maximum speed. In this paper, novel ways of incorporating peak power limits into both classical and optimal controllers are presented upon a theoretical analysis revealing its effects on stability and performance.