Fast response control for machine tool feed drives

The presence of uncertainties in a plant's parameters, disturbances acting on a system and output limitations are important obstacles to achieving high performance in an industrial controller. The optimization of such controllers for fast response is a problem of special interest in machine tool feed drives as motion errors can result in dimensional deviations on final parts. Different controllers have been introduced in the past to overcome these problems. The objective of this paper is to present a novel control algorithm to address these problems. The algorithm employs a switching technique that selects the control output from three standard controllers. Simulation results from a rotary DC motor model and experimental results using a linear motor test bed are presented to demonstrate the effectiveness of the algorithm. The approach was found to give better response for second order systems with uncertain and bounded parameters operating in the presence of disturbances while including output limitations. A 5 mm move with a 25% error In the system's mass was applied to the linear motor test bed using both the new algorithm and a PID controller. The move was completed 5 ms faster with the new algorithm.