Fuzzy PID Control of Nonlinear Vibration Isolator with Parallel Electromagnetic Negative Stiffness

Abstract

A fuzzy PID control strategy for quasi-zero stiffness (QZS) isolator which connects the pneumatic spring (PS) and the electromagnetic negative stiffness mechanism (ENSM) in parallel to suppress low-frequency vibration is proposed in this paper. First, the restoring force of PS and the electromagnetic force of the ENSM are derived. Secondly, the static analysis of the isolation system is carried out, and the analytical expressions of stiffness and restoring force of the vibration isolation system is obtained. The possibility of the vibration isolator reaching the QZS state is explained. Then, to obtain a better isolation effect, the optimal current of the coil is found according to the designed fuzzy PID control strategy. Finally, the simulation result shows that the isolation frequency band of the isolation system under fuzzy PID control and PID control is widened, and the vibration isolation performance under fuzzy PID control reaches more than 85% under different excitation frequencies. Control effect and vibration isolation performance under fuzzy PID control are better.