Vibration Control of Semi-active MR Seat Suspension for Commercial Vehicles Using Genetic PID Controller

Abstract

Nowadays, proportional integral derivative (PID) controller is the most popular control algorithm applied in engineering systems and has been generally accepted in industrial control. Recent developments in commercial vehicles have heightened the need for improving the ride comfort. The application of magnetorheological (MR) dampers in a seat suspension has been shown to provide significant benefits in this area. In most research on seat MR dampers the control application was not quite suitable for the semi-active and nonlinear hysteretic nature of MR dampers. This paper introduces an investigation into the use of a controlled MR damper for a semi-active seat suspension for commercial vehicle, enabling more suitable control. The proposed control system comprises a system controller that computes the desired damping force using a PID controller tuned using genetic algorithm (GA), and a continuous state damper controller that provides a direct estimation of the command voltage that is required to track the desired damping force. A mathematical model of a six degree-of-freedom semi-active seat suspension with human body model using an MR damper is derived. The proposed semi-active seat suspension is compared to a passive seat suspension for prescribed base displacements. These inputs are representative of the vibration of the body (sprung) mass of a passive quarter–vehicle suspension under bump and random-profile road excitation. Control performance criteria such as seat travel distance and head acceleration are evaluated in both time and frequency domains, in order to quantify the effectiveness of the proposed semi-active control technique. The simulated results indicate that the proposed genetic PID of the semi-active MR seat suspension provides a significant improvement in ride comfort.