Robust process identification and auto-tuning control

Abstract

This invention provides a novel process identification and control package for high performance. For process identification, a simple yet effective and robust identification method is presented using process step responses to give a continuous transfer function with time-delay without iteration. A new relay, called cascade relay, is devised to get more accurate and reliable points on the process frequency response. For controller tuning, the internal model principle is employed to design single-loop controller PID or high-order types with best achievable control performance. The process identification and control design parts can be easily integrated into control system auto-tuning package. Further, a general control scheme for disturbance rejection is given which can significantly improve disturbance rejection performance over conventional feedback systems with time delays. Practical issues such as noises, real-time implementation and tuning guidelines are also provided. The invention covers both open-loop and closed-loop testing, and single and multivariable cases.