Design of digital controllers for motion control systems via model reduction

An algorithm for the design of digital controllers is presented, which is based on the application of a novel power-series transformation of z-transfer functions to obtain the approximation of the ideal controller. This approach provides flexibility in choosing the settling time, the profile of the response of the system, and the order of the controller. The algorithm is very simple and fast. Good results have been achieved even when the plant has an unstable zero. The technique is extremely useful in matching the performance of the servos in a multiaxis motion control system to minimize path errors.<>