Research On Steering Control Strategy Of Double Pump Driving Motor System In Tracked Vehicle

High-speed hydrostatic drive tracked vehicle adopting hydrostatic transmission as main transmission is in line with the needs of future battlefield. Developing hydrostatic drive tracked vehicle is of great significance, and its steering control is the key technical problem that must be solved. The research object of this project is the tracked vehicle with dual pump motor drive systems, and the steering control system was designed by establishing its mathematical model. The theoretical research of its steering control strategy had been done.The system mathematical model consists of some sub-modules. The model of the variable pump driving variable motor system was completed by discussing the operation condition of the system and was based on the principle of the hydraulic control system. A simplified tracked vehicle motion module was built based on tracked vehicle dynamics first. The influence of the track slip and centrifugal force to the steering of the vehicle was taken into account, and then the actual vehicle dynamics model was established.The theoretical control scheme of the tracked vehicle with both sides independently drive was analyzed and designed. The scheme is controlling the speed of both sides of the motor. And then the influence of track slip and steering centrifugal force was analyzed by simulation. The vehicle driving control system for the actual model was designed, which can accurately realizes the driver’s input commands by controlling the speed of both sides of the vehicle. PID controller was designed for the system, and then the response characteristics of the system under PID control was analyzed.Aiming at solving the shortcomings of PID controller, this paper puts forward the strategy of using model predictive controller and the controller was designed by using MATLAB. By analyzing response of the system under different controller parameters, reasonable controller parameters were set. The simulation results showed that model predictive controller can greatly improve the dynamic response characteristics of the system. Response time reduced from 5.7 s of PID control to 1.19 s, and the response was more stable. And then the problem of single MPC controller was pointed out, which was difficult to adapt to whole scope of the work. In order to solve the problem, Multiple MPC Controllers were designed. When the system is running, controllers switch between multiple MPC controllers. The controller switching mechanism was designed, and the simulation showed that the switch was correct and smooth.Three typical steering conditions of hydrostatic drive tracked vehicle are analyzed in the simulation. By comparing with PID control, the superiority of model predictive controller was verified. The steering is steady and rapid and accurate. What is more important is that it makes the steering time reduced to 0.5 s, which improves the mobility of the vehicle. The maximum steering angular velocity the vehicle can reach under different speed was obtained through simulations. And the corresponding curve was fitted out as control curve. The speed control strategy of the system was written with the S-function, when the steering angular velocity driver input is beyond the maximum steering angular velocity the tracked vehicle can reach under current speed, which can guarantee the implementation of steering first by reducing vehicle speed. And simulation showed that this control strategy was effective.