Active Suspension Design for Passenger Cars Using LQR and GA with PID Controller

In this paper, the performance tradeoffs in the design of electronically controlled suspension systems are theoretically studied. Using quarter car model, a new treatment procedure for the control laws is introduced using fully active suspension system with two control strategies. The first strategy is considered for vehicle vibration isolation due to random road excitation only. The second strategy is considered to perform a zero steady-state suspension deflection due to body vehicle attitude variation during maneuvering, braking and aerodynamics as well as vibration isolation due to random road excitation.

The two strategies are achieved by using two different optimization techniques combined with PID (Proportional-Integral-Derivative) compensator. The first technique is based on Linear Quadratic Regulation (LQR) technique and the second technique is based on Genetic Algorithm (GA).

The results for body step input and random road are presented in time and frequency domain as power spectral density. It is shown that the second strategy offers the potential in controlling the vehicle body attitudes and vibration isolation in comparison with the first strategy without any constraint or passive suspension.