Research On Driving Control System Stability Of Four-wheel-independent-drive Electric Vehicle

Electric Vehicle (EV) has become a hot spot which various countries concern andadvance with the vigorous development of the automobile industry and increasing seriously ofenvironmental problems. Four-Wheel-Independent-Drive (4-WID) EV has better performanceof dynamics control and higher improvement space of stability and security to compare withtraditional internal combustion engine vehicles and single-motor drive EV. Technology ofdrive controller is smart control core of EV. Researching on stability control of4-WID EV,automotive attitude measurement system and drive control strategy of EV are designed.First, a radio attitude measurement system based on nRF51822for car is designed. Thesystem consists of MPU6050and a novel nRF51822which acts as a processing unit and awireless transmitter module. PC uses Labview as a development platform to display theoriginal data and attitude angle of the car via communicating with radio module of nRF51822in real-time. To compare with others, quaternion is used to solve attitude due to simplearithmetic and no singularity. Causes of error on attitude solution are analyzed. DesignedKalman filter fuses data to solve it. Experimental results demonstrate system can achieverequirement of optimal estimation car attitude angle.Second,9degrees of freedom4-WID EV dynamics module is built to analyze vehicledynamics. The corresponding simulation module is built in Matlab/Simulink by combiningwith tires and wheel module. The simulation model is validated to lay foundation for studyingdynamics of car.At last, a comprehensive drive control strategy of automotive is present by combiningwith superiority of electronic differential control and torque coordinated control. Differentstrategies are used to improve the car’s handling characteristics depending on the workingconditions. Electronic differential control based on Ackermann module is implemented at lowspeed. Torque coordinated control applied idea of hierarchical control, which divided intothree, a control variables designing layer calculates parameters of selected stability variables,a yaw moment control layer calculates value of yaw moment which automotive desired torqueneed, a driving force distribution layer allocates both sides of wheel torque in reason.Comprehensive drive control system simulation module is built and analyzed inMatlab/Simulink. The effectiveness of comprehensive drive control system in differentconditions is demonstrated.