Compliance Effect Consideration for Real-Time Multibody Vehicle Dynamics Using Quasi-Static Analysis

Abstract

HILS (Hardware-in-the Loop Simulation) vehicle simulator is one of the most effective tools to develop control subsystems for the intelligent vehicles, since expensive vehicle field tests can be replaced with virtual tests in the HILS simulator. In the HILS simulator, the software vehicle dynamics model must be solved in real-time, and it must also reproduce the real vehicle motions. Compliance effects from suspension bush elements significantly influences the vehicle behavior. In order to include such compliance effects to the vehicle model, normally the spring-damper model of the bush elements is used. However, high stiffness of the bush elements hinders real-time simulations. Thus, it is necessary to have an efficient method to include compliance effects for the real-time multibody vehicle dynamics model. In this paper, compliance model for real-time multibody vehicle dynamics is proposed using quasi-static analysis. The multibody vehicle model without bush elements is used based on the subsystem synthesis method which provides real-time computation on the multibody vehicle model. Reaction forces are computed in the suspension subsystem. According to deformation from the quasi-static analysis using reaction forces and bush stiffness, suspension hardpoint locations and suspension linkage orientation are changed. To validate the proposed method, quarter car simulations and full car bump run simulations are carried out comparing with the ADAMS vehicle model with bush elements. CPU times are also measured to see the real-time capabilities of the proposed method.