Study On Steering Contoral Strategy Of Dual-Sided Independent Electric Drive Tracked Vehicle

With the increasingly serious problems of energy exhaustion and air pollution in the world and rapid development of modern science and technology,new energy tracked vehicles are gradually replacing traditional energy tracked vehicles.At present,the power system of the new energy tracked vehicles mostly adopts the dual-sided independent electric drive structure,that is,the track on each side has an independent drive motor.In the variable steering conditions of tracked vehicles,the ground load on the vehicle has strong nonlinearity and uncertainty,which makes the driving motors on both sides run in bad working conditions and eventually leads to the vehicle's inability to turn as intended by the driver.For the reason that the steering performance has an important impact on the maneuverability of tracked vehicles,the paper studied the steering control strategies of dual-sided independent motor driven tracked vehicles.Under the condition of theoretical steering of tracked vehicles and considering the condition of track skid and slip,this paper performs the mathematical modeling of the steady steering process of the tracked vehicles separately and derives the mathematical expressions of the braking force,traction force and steering resistance moment of tracks on the two sides when steering.Based on a small dual-sided independent motor driven tracked model vehicle,this paper plotted the curves of braking force,traction force and steering resistance moment at different relative steering radius and comparing results and it can be concluded that the skid and slip of the tracks can make the tracked vehicles provide smaller braking force,traction force and steering drive moment compared to theoretical steering in the process of steering.The design of the vehicle control system is completed based on the dual-sided independent electric drive tracked vehicle structure.Besides,the vehicle control system and the tracked vehicle dynamics simulation model of the dual-sided independent electric drive tracked vehicle are built using Simulink.According to the medium-radius steering condition of tracked vehicles and the Simulink simulation model,the controllers of vehicle speed and yaw rate based on PI control algorithm are simulated and certain limitations of its steering control performance are found.Based on sliding mode variable structure control algorithm,the controllers of vehicle speed and yaw rate are redesigned.Given the fact that the sliding mode surface can cause steady-state error of the system and the traditional integral sliding mode surface can cause the integral saturation,using a nonlinear function to improve the traditional integral sliding mode surface.The quasi sliding mode equivalent control law is used to replace the ideal sliding mode control law to weaken the chattering of the system and simulation is conducted for verification.Based on the redesigned vehicle controller,the paper has simulations according to three typical steering conditions of the tracked vehicle.The effectiveness of the redesigned controllers are verified by comparing with the simulation results of the PI algorithm through the simulations.A small dual-sided independent electric drive tracked vehicle is designed and set up as the real vehicle experimental platform.The CompactRIO 9035 of NI Company is used as the controller for vehicle control and data acquisition.Besides,the vehicle control and data acquisition software of the experimental platform is designed based on Simulink and VeriStand.Real vehicle tests are carried out on the cement floor according to two steering conditions of tracked vehicle.By comparing test results,it is proven that the vehicle speed and yaw rate controllers based on the sliding mode variable structure control algorithm in the paper have superior control performance for the dual-sided independent electric drive tracked vehicle in steering conditions.