A Teaching Suggestion for Active Disturbance Rejection Control

Recently, more and more engineers and students want to learn ADRC, and teaching ADRC in the framework of mainstream control theory becomes an urgent task. This note suggests a route on teaching ADRC. It starts with the extended estimator of [1], [2], then introduces second-order linear ADRC, then generalize to n-th order linear ADRC, finally discusses the relationship between second-order linear ADRC and PID control. This route is consistent with the main stream of control theory, pays attention on both time-domain and frequency-domain, and reflects the historical progress of ADRC.