The PID Semi-Active Vibration Control on Nonlinear Suspension System with Time Delay

To improve the accuracy and precision of suspension system model of vehicle, the nonlinearity and time delay of vibration control of suspension system were considered and discussed, and a quarter car two-degree-of-freedom of vehicle nonlinear suspension system model with time delay was established. A PID semi-active control algorithm, which is easily realized in practical application and performs with strong robustness was designed to control the established suspension system. A comprehensive performance assessment criterion on suspension system was established in considering of the sprung mass acceleration, the dynamic load of tire, the suspension working space and the semi-active control force, and it was used to assess the effectiveness on the improvement of suspension system comprehensive performances with different control algorithms. Genetic algorithm was introduced and studied to optimize the parameters of PID controller. Comparisons were made to analyze the performance of PID semi-active control algorithm under simulation condition and experiment condition. The results show 1) the riding comfort of vehicle is improved dramatically (26.342%) with PID semi-active control, while the handling stability of vehicle is deteriorated by 9.964%, and the comprehensive performance is improved by 27.628%, which indicates that the designed PID semi-active control algorithm is effective and functional in improving the running performance of vehicle; 2) the sprung mass acceleration and dynamic tire deformation of suspension system with the PID parameter obtained based on linear model under experiment condition are worse (−15.191% and −16.099%) than that of passive suspension system, and much worse than that of suspension system with the PID parameter obtained based on the established nonlinear model (20.959% and 2.786%), which means that the established nonlinear suspension system model with time delay are more accuracy than the linear model; 3) the sprung mass acceleration and dynamic tire deformation of suspension system with the PID parameters optimized with genetic algorithm under experiment condition are improved (22.421% and 4.644%) than that of passive suspension system, and a little better than that of suspension system with original PID parameters, which manifests that the genetic algorithm is effective in optimizing the parameters of PID controller.