Position tracking control of a robotic joint using error-based ADRC with full and reduced order ESO

The error-based active disturbance rejection control (EADRC) structure is investigated to obtain precise tracking control of a mechanical system with one degree of freedom. We formally take into account the uncertainty of the input gain, which affects the performance of the controller, and consider stability of the closed-loop system for the full-order and reduced-order extended-state observers (ESOs). Apart from theoretical analysis, we present experimental results, which confirm that the application of the reduction-order observer can improve control performance. We also investigate whether the explicit formulation of the feedforward in EADRC makes it possible to improve the tracking precision under real conditions.