Research On Direct Yaw Moment Control Strategy Of Distributed Drive Pure Electric Tourist Bus

Distributed-drive pure electric buses have the advantages of fast motor torque response and independent controllability,which have significant advantages in improving vehicle maneuverability and driving stability.In this paper,a distributed drive pure electric coach based on hub motor is studied to design a direct yaw moment control strategy for the yaw instability of the coach on low attachment road,which improves the yaw stability of the coach when steering on low attachment road.Based on the analysis and research of pure electric bus power system,the adaptive PI speed control driver model based on BP neural network and bus power system model are built using Simulink,and the effectiveness of Truck Sim/Simulink pure electric bus model is simulated and verified under stable steering conditions to meet the requirements of bus lateral stability research by combining the steering control driver model and dynamics model in Truck Sim.Based on the simulation test of the pure electric bus model under the extreme steering condition,the factors influencing the driving stability of the bus are studied,and the judgment method of lateral instability of low adhesion road for passenger car is established.In order to improve the accuracy of the intervention timing of the direct yaw moment control strategy,the steering simulation test is conducted under the conditions of no load and full load with the vehicle speed of 50-100km/h and the adhesion coefficient of 0.1-0.5,and the thresholds for the difference in angular velocity of the transverse pendulum and the difference in lateral acceleration during lateral instability of the bus are determined;considering the effects of vehicle speed and adhesion coefficient on the destabilization threshold,the lateral instability judgment model of low adhesion pavement under no-load and full-load conditions is established.To address the problem of bus load variation affecting the determination of instability on low-adhesion roads,the quality estimation algorithms based on weighted recursive least squares method is designed.The simulation results show that the algorithm can quickly and accurately identify the mass of the bus when the bus is moving at a certain speed after starting,and the estimation error is within 70 kg.The direct yaw moment control strategy is designed to improve the lateral stability of the bus when steering on low adhesion roads.The start-stop control is designed based on the instability judgment of the low adhesion road to realize the active intervention and withdrawal of the direct yaw moment control strategy;the upper controller is designed based on the adaptive LQR to solve for the additional yaw moment required to maintain the lateral stability of the vehicle;the lower controller is designed based on the tire load rate optimization to calculate the desired output torque of the motor.In order to verify the effectiveness of the direct yaw moment control strategy,a simulation platform based on Simulink and Truck Sim is built,Simulation results show that the control strategy can achieve active intervention and automatic withdrawal,and the root mean square error of the lateral deflection angle of the center of mass is within 0.6° and the root mean square error of the angular velocity of the yaw pendulum is within 2.3°/s In order to verify the realtime performance of the control strategy,a real-time simulation test platform based on d SPACE,Simulink and USB to CAN device is built,and sinusoidal input test and angular step input test are carried out.The simulation results show that the control strategy can guarantee the real-time tracking control of the ideal transverse pendulum angular velocity and the lateral deflection angle of the center of mass and meet the design requirements.