Research On Steering Control Strategy Of High-Speed Tracked Vehicle Driven By Mechanical-electric Transmission

With the increase of the maximum speed and the cross-country speed of tracked vehicle,the stability problem has been widely paid attention to.At the same time,the electromechanical transmission technology is rapidly developed.Electric motor to realize steering is adopted in this paper.Compared with hydraulic pump motor,electric motor has the advantages of faster response and more precise control,providing the foundation for better steering process control.On the other hand,some stability control theories have been well developed and put into use in the wheeled vehicles,being widely recognized by the consumer market.This also provides a great reference for the study of high-speed tracked vehicle steering.Therefore,the steering control of high-speed tracked vehicle driven by MechanicalElectric Transmission is studied in this paper.A more accurate tracked vehicle steering model used for real-time simulation is built in Matlab/Simulink.The force between ground and track is determined by shear effect in this model considering track slip and centrifugal force.The model is integrated into the electromechanical drive system,and the speed control strategy is established to simulate the test vehicle equipped with this transmission.Through simulation experiments,the instability steering process of tracked vehicle under steering control strategy is exhibited and the cause is analyzed.The the tracked vehicle steering response performance is also summarized,laying the foundation for more accurate control of steering process.On the basis of the previous analysis,the Ideal Trajectory Self-Adaptive PID control strategy is established,consisting of reference model,state estimation and the compensation torque generation of the steering motor.Two degrees of freedom linear tracked vehicle steering model is used as reference model and its parameters is adjusted to make sure reference response exported not only meets the driver requirements,but also within the range of vehicle steering capacity.Adopting Calman filtering algorithm to estimate the yaw rate so that we could judge whether the vehicle is stable or not and the yaw rate sensor is function or not;The torque commands received by the steering motor include the steering wheel input torque generated by torque control strategy and compensation torque.The compensation torque is generated by the self-adaptive PID model in comparison with the actual yaw rate and reference yaw rate.The steering stability of tracked vehicles is compared between the speed control strategy and the model following steering control strategy under various road condition.The simulation results show that,with the steering wheel opening increased evenly,when the ground could not produce enough lateral force to support the steering of the vehicle,the yaw rate of the vehicle will increase suddenly,resulting in sudden increase of sideslip speed and instability of the vehicle under speed control strategy.The yaw velocity always follows the change of the steering wheel under Ideal Trajectory Self-Adaptive PID control strategy.The steering stability of tracked vehicles is greatly enhance.According to simulation of tracked vehicle under ground resistance mutation interference,model following steering control strategy keeps the yaw rate at a stable range improving the ability to resist the interference of ground.While with the speed control strategy,the yaw rate response fluctuates obviously.The driver have to adjust the steering wheel frequently to ensure the stable steering process.That is to say,the model following steering control strategy can replace the driver's work partly and significantly reduce the driver's burden.