Output Feedback ILC for a Class of Nonminimum Phase Nonlinear Systems with Input Saturation: An Additive-State-Decomposition-Based Method

In this technical note, an additive-state-decomposition-based iterative learning control (ILC) method is proposed. Based on this method, the output feedback ILC problem is solved for a class of nonminimum phase (NMP) nonlinear systems with input saturation. This method is to 'additively' decompose the output feedback ILC problem into two more tractable subproblems, namely an output feedback ILC problem for a linear time invariant (LTI) system and a state-feedback stabilization problem for a nonlinear system with input saturation. Then, a controller can be designed for each subproblem separately using existing methods, and the two designed controllers are combined together to achieve the original control goal. An illustrative example demonstrates the effectiveness of the proposed method.