Vehicle Modeling Methods for Real-time Dynamic Simulation Using Suspension Composite Joints*

New vehicle modeling methods for real-time dynamic simulation using suspension composite joints are presented. The suspension composite joints are derived and utilized to reduce the computation time of the simulation without any degradation of kinematic accuracy of the suspension systems. The joints are modeled using massless links on the suspension members that have small masses but have important kinematic functions, and the kinematics of the knuckles or axles of suspension systems are derived. Three vehicle modeling methods are tested using the joints: kinematic steering, compliant tie-rod, and force driving steer vehicle models. The latter two are constructed to represent the steering compliance characteristics of a real vehicle. The accuracy of the simulation results of each vehicle model is verified through comparisons to the results of real vehicle field tests and simulation with an ordinary full multibody vehicle model. It is found that the simulation results using the proposed vehicle models are accurate, and real-time simulation is achieved on a computer with a single PowerPC 604 333 MHz processor with 1 millisecond of integration step size.