The application of setpoint gain scheduling to improve the performance of high speed independent drives

For independent drives to give comparable performance with mechanically coupled systems advanced control techniques have to be employed, to compensate for the inherent lack of stiffness in servo motor air gaps. This paper discusses the application of setpoint gain scheduling (SPGS) to high speed independent drive systems. Setpoint gain scheduling involves switching between controllers at setpoints within the event cycle in order to improve performance as measured by a particular error law. Its use is demonstrated on an industrial design problem, both in a nonlinear simulation and on a corresponding test rig at Aston University. The results are compared to non-varying controllers based on PID with velocity feedforward and a H_∞-norm optimisation technique, and show that a dramatic reduction in cycle time is possible. The benefits in terms of increased productivity, leading to reduced costs, are briefly analysed