An enhanced fuzzy PD controller with two discrete nonlinear tracking differentiators

An enhanced fuzzy PD (EFPD) controller by incorporating two discrete nonlinear tracking differentiators (TDs) into a conventional fuzzy PD controller is proposed. This work is motivated by the fact that the performance of the controlled system is limited by how to select a high-quality differential signal in the presence of noise, based on the noncontinuous measured position signal only. The proposed TD is constructed based on the fact numerical integration can provide more stable and accurate results than numerical differentiation in the presence of noise. The proposed EFPD controller is easy to implement, and exhibits better control performance than conventional fuzzy controllers, with especially high robustness against noise. Comparative simulations and experiments with a linear observer performed on a permanent-magnet synchronous motor system are presented to demonstrate the better performance of the controller.