Root Locus and b0 Selection of First-Order Linear Active Disturbance Rejection Control Systems

This paper investigates first-order linear active disturbance rejection control (LADRC) with root locus approach. It re-proves that for the first-order plant, if $b_{0}$ has a correct sign, then the stability of the LADRC system can be guaranteed by tuning parameters, no matter the plant is stable or not. With theoretical analysis and numerical examples, it shows $b_{0}$ can be viewed as a tuning parameter and tuning $b_{0}$ along root locus may improve the system's performance.