The fundamental goal of any suspension system is the isolation of a structure from external excitation. In the case of a vehicle, a classical car suspension aims to achieve isolation from the road by means of a spring type element and a viscous damper. The characteristics of the elements of the suspension are chosen according to comfort, road holding and handling specifications. A suspension unit should be able to reduce chassis acceleration as well as dynamic tyre force within the constraints of a set working space and with minimal energy consumption.
The design of an automotive suspension has been a compromise between the three conflicting parameters of road handling, load carrying and passenger comfort. The passenger comfort is given more importance in suspension design. For the past three decades, the introduction of increasingly sophisticated electronically controlled components into automotive suspension, give better comfort.
In this paper, an experimental setup of quarter car model to study the performance improvement of active suspension system has been explained. The road disturbance was created by a cam. The electronic control unit receives the information from the displacement sensor mounted on the sprung mass. Based on the input data, the control law was applied to counteract the road disturbance. The sprung mass displacement is controlled by a hydraulic actuator which is controlled by the spool movement of proportional control valve based on the control law.
A mathematical modeling of a typical vehicle has been developed by considering the sprung mass and unsprung mass. Second order differential equations of motion are derived for quarter car model and forced quarter car model with damping. Then the second order differential equations of motion are transformed into a standard eigen value problem. Then it is solved by using MATLAB. The dynamic study of the behavior of a quarter vehicle and the performance improvement of the proposed concept are carried out using the simulation results obtained from the mathematical modeling.
