Modeling and Simulation of an Active Car Suspension with a Robust LQR Controller under Road Disturbance, Parameter Uncertainty and White Noise

TL;DR

This paper designs a robust LQR-controlled active suspension system that outperforms passive and PID-controlled suspensions in comfort and safety under various road disturbances and uncertainties.

Contribution

It introduces a robust LQR control approach for active suspension systems and compares its performance against passive and PID-controlled systems under multiple disturbances.

Findings

LQR-controlled suspension has the fastest response time.

LQR suspension exhibits the least overshoot.

LQR suspension provides the most comfortable and safe ride.

Abstract

Vehicle suspension is important for passengers to travel comfortably and to be less exposed to effects such as vibration and shock. A good suspension system increases the road holding of vehicles, allows them to take turns safely, and reduces the risk of traffic accidents. A passive suspension system is the most widely used suspension system in vehicles due to its simple structure and low cost. Passive suspension systems do not have an actuator and therefore do not have a controller. Active suspension systems have an actuator and a controller. Although their structures are more complex and costly, they are safer. The Proportional-IntegralDerivative (PID) controller is widely used in active suspension systems due to its simple structure, reasonable cost, and easy adjustment of coefficients. In this study, a more robust Linear Quadratic Regulator (LQR)-controlled active suspension was designed than a passive suspension and a PID-controlled active suspension. Robustness analyses were performed for passive suspension, PIDcontrolled active suspension, and LQR-controlled active suspension. Suspension travel, sprung mass acceleration, and sprung mass motion simulations were performed for all three suspensions under road disturbance, under simultaneous road disturbance and parameter uncertainty and under road disturbance with white noise. A comparative analysis was performed by obtaining the rise time, overshoot, and settling time data of the suspensions under different conditions. It was observed that the LQR-controlled active suspension showed the fastest rise time, the least overshoot and had the shortest settling time. In this case, it was proven that the LQRcontrolled active suspension provided a more comfortable and safe ride compared to the other two suspension systems.