Design And Control Of All-wheel Steering System For Six-wheel Electric Vehicle

The main working environment of off-road vehicles is harsh working conditions such as unpaved roads.In recent years,off-road vehicles have been widely used due to their good passability.In off-road vehicles,multi axle vehicles have better trafficability.Among multi axle vehicles,three axle six wheel vehicles have both smaller dimensions and good trafficability,making them the best choice for off-road vehicles.However,the flexibility of six wheel vehicles is poor,and the design of the steering system has become a key step in improving the flexibility of six wheel vehicles.This article conducts research on the steering system of six wheeled vehicles,and the specific research content is as follows:(1)The steering mode of the steering system is designed,and the vehicle is designed according to the requirements of the steering mode.Firstly,the working environment of the three-axle six-wheel off-road vehicle is analyzed and the expected function of the system is proposed;Then the steering mode is designed according to the expected function of the system,and kinematics models are established for different steering modes,and kinematics analysis and calculation are carried out;Finally,a test vehicle is designed to meet the requirements of the steering system.The vehicle is driven by an in-wheel motor and a suspension system is designed to achieve large wheel steer angles,enabling the wheels to steer at large angles to meet the requirements of the steering system.(2)The steering system is analyzed,researched and designed according to the expected function and steering mode of the vehicle.Firstly,the steering trapezoid parameters of the vehicle are designed and optimized according to the results of kinematics analysis and calculation of the steering mode of the first two wheels.Then the design of the steering gear is carried out,the three-dimensional model of the steering gear is established and the relevant parameters of the steering gear are calculated.Finally,the finite element analysis and optimization of the key parts of the steering gear are carried out.Through the optimization results,it can be seen that the bending deformation of the key parts of the steering gear under the maximum load is less than0.1mm,which meets the use requirements.The steering system designed in this paper can realize the combination of mechanical steering and drive-by-wire steering,and both have a variety of steering modes.(3)The steering-by-wire system is designed.Firstly,according to the mechanical structure of the steering gear,the hardware architecture of the steering-by-wire system is designed and the hardware is selected.Then the control strategy of the steering-by-wire system is designed and the control program is developed,including the main program and the wheel steering angle control subroutine based on PID.The main program and the wheel steering angle control subroutine based on PID are tested respectively through simulation experiments.The experimental results show that the steering by wire system can realize a variety of steering by wire modes,and the wheel steering angle control subroutine based on PID can control wheel steering angle more accurately.(4)A test prototype is built and the performance of the steering system is verified by the test prototype.Firstly,the engineering drawing is drawn according to the three-dimensional model,and the test prototype is processed and assembled.Then the functional test of the steering system is carried out based on the test prototype,and the real vehicle test of the multi-steering mode is carried out.The experimental results show that the all-wheel steering system of the six-wheel electric vehicle designed in this paper has good performance.