The Study Of Off-road Vehicle Dynamics Simulation Based On Active Suspension

When the vehicle is traveling, it receives complex force and moment from the ground. The suspension system can effectively mitigate the impact load of the body from the road surface roughness. Off-road vehicles often pass through poor and complex roads, with large suspension displacement, remarkable non-linear damping characteristic and time variability at the same time. Conventional passive suspension system is unable to meet the needs of real-time adjustment. Consequently, it's necessary to develop the active suspension of the off-road vehicle.ADAMS is a analysis software, with function to solve large displacement and nonlinear problems. As we apply the CAR specialized module, the vehicle physical system model can be changed into multi-body dynamics mathematical model, so we get more accurate quantitative analysis result. MATLAB/SIMULINK module can effectively achieve a variety of modern control methods.This paper studies on a certain light type of off-road vehicles. First of all, with ADAMS/CAR as a platform, we create the vehicle dynamics model. According to the key hard points, mass parameters and the like, we modify the templates and parts, then establish the antiroll bar, wheel system, body system and braking system models; On the basis of analyzing the power train template of ADAMS/CAR, we build the four-wheel driving dynamic system by adding communicators and kinematic pairs; while editing the parameters of double wish-bone suspension template, for the active suspension, we establish the input variables in ADAMS/Control and add force actuators which will change with the input variables, therefore, the front double wish-bone suspension and the rear double wish-bone suspension (active, passive)are completed. Secondly, on the base of analyzing the kinematics and elastic kinematics evaluation index, we make the front double wish-bone suspension experimental simulations, such as parallel wheel travelling, static external load, roll and vertical force, discuss the influence of wheel camber angle, toe angle, kingpin inclination angle, caster angle and suspension stiffness variation for driving stability. Finally, we establish the ADAMS/CAR vehicle model with active suspension system. While using MATLAB/SIMULINK to realize the co-simulation, We complete the uneven road experimental simulation to contrast the driving stability and ride comfort performance of active double wish-bone suspension full car model with the passive one. By contrasting different control methods, we propose to use decentralize control theory, which can decouple the vehicle vertical control goal, roll control goal and pitch control goal into four interrelated goals firstly. The system retains the advantages of line control by decoupling matrix. Then we use PID control, fuzzy PID control and neural fuzzy control in the co-simulation. The co-simulation results show that:PID control vehicle system performs better than passive suspension vehicle system, for the chassis body vertical acceleration and pitch angular acceleration decrease obviously; Fuzzy PID control responses quickly, and its robustness is more excellent than PID control; Neural fuzzy control can effectively inheritance the advantages of the PID control and fuzzy PID control by training data studying, consequently, it shows the optimal control performance.