The Simulation And Analysis Of Fourteen-degree-freedom Vehicle Dynamic Model

Virtual prototyping technology of automobile has become the core technology for major car manufacturers to reduce the period and cost of design and development. As the vehicle dynamic model is the basis of automotive virtual prototyping technology, therefore, how to establish a vehicle dynamic model with more practical and higher fidelity becomes a key step in the process vehicle development.Currently, the more sophisticated modeling method is applying the theory of multi-body dynamics to establish the structure-oriented dynamic model. This kind of model simulate the actual movement of the vehicle in combination with the actual structures and constraints of the vehicle.Therefore, it has a high precision and versatile, but there are some disadvantages in terms of computing speed and it cannot meet the requirement of real-time simulation.This article will simplify the vehicle into a multi-body system and establish the inertial coordinate system N, the body coordinate system A, the intermediate coordinate systems Bi and the tire coordinate systems W(then describe the mutual motion relations among the rigid bodies through the four different coordinate systems. Through defining the wheel gesture combined with suspension K&C characteristics and unit vectors, calculate the tire forces according to MF tire model. According to the mechanics and kinematics analysis of the vehicle body and suspension systems, establish the object-oriented dynamic model of14DOF, including three axial linear displacements, three axial angular displacements, four suspension deflections and four tire spin degrees of freedom. Apply the improved Euler method to solve the differential equations and develop the corresponding dynamics simulation software in the Matlab environment to make the model more convenient to use and more intuitive.Finally, this paper simulate the conditions of linear braking, steering wheel angle input and steady rotation using model of derivation and Adams in combination with the sample vehicle and contrast with Adams from the accuracy and computational efficiency of simulation. The results showed that the simulation results of both models match well, moreover, the computing efficiency of derived model is much higher than Adams, which prove its accuracy and practical value, and the important theoretical significance of developing chassis control system.