Suppression of Pitch Angle Vibrations of a 5-DOF Half Vehicle Model by System Identification Method

Abstract

A vehicle's suspension system helps to enhance the driver comfort, road handling, ride quality and steering stability. It is desirable to limit the angular displacements of the vehicles for comfort design. Pitch angle is an angular displacement of the body between the front and rear tyres. In this work, the active control of a 5-degree of freedom (DOF) half vehicle (HV) model with a driver is studied to reduce the pitch angle.  A force based actuator between the body and front tyre together with a driver mass is considered. The mathematical model of the system is obtained by using the system identification (SI) method. Inputs of the system are the road profiles for the front and rear tyres and actuator. The output of the system is the pitch angle. Finite element vibration analyses are performed to obtain the output response to the given inputs. The transfer functions of the system are found by utilizing the inputs and output with the parametric SI models. Then, the closed-loop control is applied to the system to control the pitch angle.  The values of the peak and settling time of the pitch angle response are successfully reduced with various PID gains.