Constant speed control of a motor driven mechanism system

Abstract

One of the basic assumptions in both the synthesis and analysis of many four-bar mechanisms is that the angular velocity of the input crank is constant. However, this assumption may not be valid when an electric motor is connected to drive the mechanism. In this study, the motor-mechanism combination is treated as a single system, and control strategies are developed to efficiently reduce the crank angular speed fluctuation of a four-bar linkage. A complete mathematical model for the controller-motor-mechanism is developed, using a state space representation. Based on the principles of conventional PID control and the information obtained from steady state constant speed analyses, several modified PID type control strategies are developed. Nonlinear programming techniques are utilized for the determination of optimal controller gains. Numerical simulations show that, by using feedback control, the crank speed fluctuation can be reduced substantially.