Controllers design of an active suspension system based on half car model

Abstract

Most automobile suspension systems use passive components which are combination of spring and damper only. These components can only store and dissipate energy, and lack the capability to inject energy into the systems. The parameters of these components are generally fixed and do not vary with operating conditions. In this project, hydraulic actuators are considered in parallel with the passive components to make the systems active suspension so that the system will have the ability to store, dissipate and introduce energy to the system. The mathematical model of the active and passive suspension systems based on half car was derived and represented in state space form for controllers design, analysis and comparison. The control of these active suspensions will improve the load carrying, road handling and ride quality of the car. Three suitable controllers, one state feedback-Linear Quadratic Regulator (LQR), one intelligent-Fuzzy Logic (FL) and Proportional Integral Derivative (PID) controllers were designed and applied to control active suspension in order to improve ride comfort. This was achieved by minimizing the vertical displacement and acceleration of the car body through simulation results. Comparison and analysis of the performance of each controller in relation to ride comfort and road handling was presented. The simulation results were obtained using Matlab/Simulink software with a road profile as input to the system.