A Bumpless Switching Multiple-Controller Design for Nonlinear Systems Based on Integrated Stability and Performance

This paper focuses on designing multiple-controller for nonlinear dynamic systems. An algorithm is proposed that integrates two stages of selecting the nominal local models and designing the local controllers. The proposed algorithm does not need to a priori knowledge about the system and a prior experience to choose the gridding threshold. In order to design the local controllers, the stability and performance criteria are integrated and the local controllers have a simple Proportional-Integral (PI) structure. Although the simple local PI controllers lead to have a simple global multiple-controller, but the bump phenomenon occurs when switching between the active local controller in the closed-loop and another controller in the off-line controllers set waiting to take over the control loop. In order to solve the lift-off and landing issues by switching among different local controllers, a linear quadratic bumpless transfer method is used in the closed-loop. The off-line local controllers were not fed by the error signal to have a bumpless switch. Therefore, the proposed multiple-controller design method provides support to have a gentle switch among different local controllers. To evaluate the proposed method a nonlinear CSTR is simulated. The simulation results demonstrate the success of the proposed method in set-point tracking with a smooth control signal in comparison with the opponents.