Uniform output regulation via approximated input-output linearisation for lightly damped internal dynamics

We present a general framework for the design of a damping controller to tame lightly damped internal dynamics and to assess the stability of an approximate inputoutput linearised closed-loop system. In nonlinear systems, conclusions cannot be drawn regarding the stability of internal dynamics even though the zero dynamics is globally stable. Here, we investigated the sufficient conditions with a parameter-dependent Lyapunov (PDL) function for semi-globally exponential stability of damped internal dynamics. Using a composite Lyapunov function based on the PDL function, the uniform boundedness of the output regulation error is established within a region of interest. Controllability and observability analyses offer a theoretical guideline as to how a damping controller can be designed in the view of control effort and transient performance.Power Generation and Electricity Delivery of the Korea Institute of Energy Technology Evaluation and Planning (KETEP)Ministry of Knowledge Economy, Republic of Korea National Research Foundation of Korea (NRF) Korea government (MEST