Control of active suspension for full car model

Abstract

The need for passenger comfort, road handling abilities of tires, and vehicle handling characteristics, have been the major challenge in the design of suspension system over the years. However, in the past decades various strategies ranging from semi-active to fully active suspension systems had been developed to minimized the unavoidable compromised adopted in the design of passive suspension system, and improve the performance of suspension system. This leads to many research works on active suspension system, with most of them focusing on quarter car model. The quarter car model was mostly used due to its simplicity and proximity in capturing many of the vehicle characteristics. But in order to capture all or most of the vehicle real characteristics, recent studies are focusing on the full car model so that best performance that is very close to real system can be obtained. This project study full car, seven degree of freedom (DOF), suspension system by simulating both passive and active suspension models under two different road profiles. Actuators and controllers were also studied and a Linear Quadratic Regulator (LQR) is propose due to its robustness, the Q and R parameters were carefully tune using Brayson’s rule and Trial and error method for best performance. The results obtained confirmed that LQR controllers can reliably ensure system stability, improved road handling abilities and improved overall system performance. Finally, a Linear Quadratic Regulator (LQG) was designed and implemented in the system to validate the proposed controller, the result obtained are very similar.