Research On Driving Technique Of Vehicle On Virtuai Orbit

Tramcar is a kind of urban rail transit system that is between Bubway and Bus system.It is mainly used to solve the insufficient capacity problem of traffic system of medium-sized city.But it still has two obvious drawbacks:(1)the need for a proprietary orbit and the costs is costly;(2)the wheel and rail noise affect the surrounding environment.Vehicle on virtual orbit is a new type of transportation system combined with Bus and Tramcar.It is a 100%low floor electric vehicle running along the "preset" virtual orbit with rubber tire,but it is different from the traditional trolleybus.The core of the vehicle on virtual orbit is the independent wheel-oriented differential guidance technology.Based on the project of Research On Driving Technique of Vehicle On Virtual Orbit of Traction Power Laboratory,the following work was carried out:Modeling and simulation of four-wheel independent drive system.In this paper,the working principle and mathematical model of brushless DC motor are analyzed.And based on MATLAB/Simulink simulation platform,the model of independent drive system of four brushless dc motor with hall sensors with method of PWM_ON pulse and speed current double closed loop is built,which includes:Commutation module,speed current double closed loop module,PWM pulse generating module.The results show that the four-wheel independent drive system is feasible,and it has good dynamic and static performance.Research on four-wheel independent driving differential steering control method.Analyzing and comparing the classic Ackerman differential steering model of independent wheel and the front rear wheel reverse rotation differential steering model,the latter reduces a half of the radius,which can effectively improve the steering flexibility of the vehicle.Therefore,this paper chooses the front and rear wheel reverse rotation differential guidance control as the steering method of virtual railway vehicles.Development of four-wheel independent drive differential steering controller.Based on the above-mentioned motor control method and steering method,a four-wheel brushless DC motor independent drive system based on DSP + FPGA architecture is developed,which includes:hall signal sampling module,analog signal sampling module,power supply module and other auxiliary circuit module.Performance verification of four-wheel independent drive system.In the vehicle on virtual orbit equipped with the four-wheel independent drive system,the no-load and road-load running experiments are carried out.The results show that:(1)the speed of brushless dc motor response rapidly,and the steady-state precision is high;(2)The experimental vehicle can realize the fast tracking of the line speed command;(3)The experimental vehicle has some differential guide capability.