Multi-Objective Optimization of Nonlinear Quarter Car Suspension System - PID and LQR Control

This paper presents modeling, control and optimization of a nonlinear quarter car suspension system. A mathematical model of nonlinear quarter car along with seat and driver is developed and simulated in Matlab/Simulink® environment. Input road condition is taken as class C road and vehicle travelling at 80kmph. Active control of suspension system is achieved using PID and LQR control actions. Instead of guessing and or trial and error method to determine the PID and LQR control parameters, a GA based optimization algorithm is implemented. The optimization function is modeled as multi-objective problem comprising of frequency weighted RMS acceleration, VDV, suspension space, tyre deflection and controller force. It is observed that optimized parameters gives better control as compared to the classical parameters and passive suspension system. Further simulations are carried out on suspension system with seat and driver model. The PID controller gives better ride comfort by reducing RMS head acceleration and VDV. Results are presented in time and frequency domain.