Design And Test Of Torque Distribution Controller For Intelligent 4WD Vehicle

Intelligent all-wheel-drive technology is the development trend of future all-wheel-drive vehicles,the performance of torque distribution controller determines the four-wheel-drive vehicles carrying all-wheel-drive system performance.On the basis of investigating and researching the all-wheel-drive technology status presented at domestic and international in this paper,the core of the control technology applying in several typical all-wheel-drive system has been analyzed and the device torque distribution between transmission shaft has carried on the detailed analysis and research,obtained the device's relationship about the torque distribution between front transmission shaft and rear.By the exploration of working principle of electronically controlled multi-plate electromagnetic clutch,this paper gains the mathematical expression of clutch friction torque,describes in details the working process on some kind of electronic transfer case.On this base,the studies on all-wheel-drive car the torque distribution system structure and control scheme has been identified in this paper.In view of the design scheme,this paper uses the Freescale MC9S12XS256 CAA chip as the core to carry out the all-wheel-drive vehicle torque distribution controller hardware design,detailed introduces the specific design scheme of the controller's core circuit,power circuit,reset and BDM circuit,electromagnetic coil driver circuit,the input signal processing circuit,and CAN bus communication circuit,and describes the PCB design method of hardware anti-jamming in this control system.Based on the analysis of the vehicle torque distribution control technology,this paper combines hardware structure of control system and the technical implementation scheme,writes software code of torque controller: on the CodeWarrior development platform,the control system software framework,CAN bus communication program,data acquisition program,PWM driver program has been given out,part of the program flow diagram is given,and the slip rate calculation method in the operation of vehicle are expounded,and the wheel slip ratio control was designed for the torque distribution control method based on logic threshold controller,identified torque distribution control target under the three typical condition of vehicle.This developed torque distribution controller is under the functional verification,the hardware and software of all controller module has been function debugging andoptimization through the test instrument.To test control performance is good or bad,a torque distribution controller real vehicle tests platform has been set up,and the vehicle performance data acquisition system has been developed based on the Labview software,through the analysis of real vehicle tests under different driving conditions,a conclusion has drawled that when a test vehicle with its torque distribution controller involved in power distribution,the vehicle drive power and acceleration has larger rising,so that verify the effectiveness of the developed torque distribution controller performance to control the four-wheel drive vehicle.