Additive-State-Decomposition-Based Tracking Control for TORA Benchmark
  In this paper, a new control scheme, called additive state decomposition based tracking control, is proposed to solve the tracking (rejection) problem for rotational position of the TORA (a nonlinear nonminimum phase system). By the additive state decomposition, the tracking (rejection) task for the considered nonlinear system is decomposed into two independent subtasks: a tracking (rejection) subtask for a linear time invariant (LTI) system, leaving a stabilization subtask for a derived nonlinear system. By the decomposition, the proposed tracking control scheme avoids solving regulation equations and can tackle the tracking (rejection) problem in the presence of any external signal (except for the frequencies at +1 or -1) generated by a marginally stable autonomous LTI system. To demonstrate the effectiveness, numerical simulation is given. 
Quan Quan and Kai-Yuan Cai
cs.SY