A design of servo controller with SDRE for nonlinear systems

In this paper, we propose a new servo controller design method for nonlinear systems, which can be considered as an extended version of the Smith-Davison type servo controller. The control input of the controller is given by computing the Riccati equation dependent on the state, which is called the SDRE (state dependent Riccati equation), repeatedly at each sampling time. A nonlinear optimal control law by solving the SDRE was proposed by Cloutier et al.(1996) to stabilize nonlinear systems. To verify the effectiveness of the approach, we show a numerical example where the swing-up and stabilizing control for a rotational type pendulum is designed.