Active disturbance rejection control for spacecraft attitude

To inhibit the variation of spacecraft structure parameters and the influence of interference on attitude control accuracy and attitude stability, an active disturbance rejection controller (ADRC) was designed. ADRC consist of three parts: Tracking Differentiator (TD), Extended State Observer (ESO) and Nonlinear State Error Feedback (NLSEF) Controller. TD smooth out the process of attitude transformation and provide differential signal of attitude. Compared with general forms of ESO, this ESO takes full advantage of the information of the gyros and attitude sensors with high observation precision and fast convergence. The variation of spacecraft structure parameters can be observed and compensated by the controller, so the spacecraft system was less sensitive to disturbance. NLSEF compensate the estimated disturbance. Simulation results demonstrate that the ADRC can meet the requirements on the high accuracy of spacecraft attitude control and achieve better performance in case of structural parameters uncertainty and large disturbance.