Research On Driving Control System Of Virtual Orbit Vehicle

Virtual rail transit is a new mode of transportation which has only been being developed in recent years.It does not require steel rails and uses rubber tires to support the vehicle body,so the noise is less and the construction cost is lower.Combining the advantages of rail train and bus,virtual rail transit is a very promising mode of transportation.The core technologies of virtual rail transit include track tracking technology,drive control technology,virtual track identification and navigation technology,etc.Based on the virtual orbit vehicle project,this paper designs a drive control system for virtual orbit vehicle based on permanent magnet brushless DC hub motor,focusing on solving the problems of virtual orbit vehicle straight running,steering control and anti-slip regulation.The details are as follows:Firstly,the working principle of brushless DC motor of virtual orbit vehicle was studied in detail,and the commutation torque ripple of the motor under different PWM modulation modes was deduced,and the motor double closed-loop control mode of outer loop of speed and inner loop of current was designed for it.Secondly,based on the Ackermann steering model,the front-wheel differential steering control system of the virtual orbit vehicle was designed,the driving skid problem of the vehicle on the low-adhesion road surface was studied,and the driving anti-skid control algorithm based on the optimal vehicle skid rate was designed.Finally,a simulation model of the virtual orbit vehicle drive control system is established through the establishment of the Car Sim and Simulink co-simulation platform.The simulation related to the vehicle and road surface is established by Car Sim,and the simulation related to the motor drive control algorithm is realized by Simulink.The simulation results show that the motor double closed-loop control system has a fast response speed and low speed overshoot.At the same time,it is verified that the addition of the anti-slip regulation control system can effectively reduce the occurrence of driving skid.On this basis,the hardware design of the virtual orbit vehicle drive control system based on ARM+FPGA is completed,in which the ARM chip is responsible for communicating with the experimental data acquisition system and the master control chip,issuing instructions and saving data,etc.FPGA mainly completes PWM pulse generation,control logic level input and output,realizes the capture of Hall position pulse signal,completes the calculation of motor speed and analog signal sampling,processing fault signals,etc.,followed by the design of peripheral conditioning hardware circuit for the main control chip.Finally set up a virtual orbit vehicles drive control experiment platform,and on the control algorithm is designed on the basis of the experimental verification of the vehicle drive control experiment.the experimental results show that virtual prototype orbit can realize four-wheel independent wheel motor drive control and complete straight line driving operation,and has initially electronic differential steering function.As a whole,the results are in good agreement with theoretical analysis and simulation.