Auto-tuning of multivariable decoupling controllers

Abstract

Controller parameters for multivariable systems with interacting loops are difficult to tune. However, using feedforward compensators or decouplers, the interaction can be appropriately compensated so that effective non-interacting single-input/single-output processes are obtained. It then allows application of tuning techniques for single-loop PID controllers to the individual loop. This method, though simple in concept, is difficult to implement manually as it is tedious and time consuming. In this paper a method to automate the process of determining the transfer functions of the decouplers and the tuning of PID parameters is presented. Typical 2-input/2-output plants are used as simulation examples. The controller is implemented on a microcontroller and tested on a portable simulator. Results show significant reduction in interaction and satisfactory tuning performance.