Research On Control Strategy Of Yaw Stability For Multiwheel Independent Electric Articulated Bus

Multi-wheel independent electric articulated bus combine the advantages of both electric bus and articulated bus.With large body capacities,strong road surface adaptability,better steering performance and zero emissions,it is the ideal solution for future urban traffic problems.The vehicle dynamics system is more complex than general vehicle.It has many dynamic characteristics that are superior to the traditional centralized driving vehicle,and there are differences between the general four-wheel wheel-driving electric vehicle and this kind of vehicle.In terms of handling stability,there are obvious differences compared with ordinary vehicles,including folding,rollover,tail flick and lateral swinging.In this paper,focusing on the yaw stability control of multi-axis distributed driving articulated bus,the main contents are stated as follows.1)Establish vehicle dynamics model and build dynamic simulation platformAccording to the dynamic and kinematic analysis,an 11-DOF dynamic model of the vehicle was established including the rotational freedom of the six wheels,the vertical and lateral speeds and the yaw rate of the front carriage,the hinge angle and the steering angle.Established mathematical models including tires,hinged plates,motors,transmission systems and drivers.Built a vehicle dynamics simulation platform based on these models,and the feasibility of the dynamics simulation platform was verified by comparing the running results of the built dynamics simulation platform and the d SPACE-ASM simulation platform under the same conditions.2)Research on the yaw stability control strategy of vehicleFor the problems of folding,tail flick and lateral swing,the yaw stability control strategy of the vehicle was developed.Using stratified control method,the upper layer is the motion tracking layer.Firstly,a 3-DOF reference model is established to provide ideal vehicle response.The yaw rate is the main control target of the front carriage and the hinge angle and yaw rate are the control targets of the rear compartment.Sliding mode control method is used to calculate the additional yaw moments of the front and rear carriage.The lower layer is the torque distribution layer.Designed the quadratic programming problem with the tire utilization rate as the optimization goal.And the effective set method is used to calculate the longitudinal forces.3)Strategy validation based on vehicle dynamics simulation platformApplying the developed yaw stability control strategy on the vehicle dynamics simulation platform,let the simulation run under the low-speed and high-speed conditions of the sinusoidal input of the steering wheel angle.By observing the yaw stability indicators such as the vehicle speed,the yaw rate and the hinge angle,the control effect is evaluated.The simulation results show that the developed control strategy can effectively improve the yaw stability of the target vehicle.4)Multi-condition simulation based on d SPACE-ASM simulation platformAfter preliminary verification of the control strategy on the dynamic simulation platform,use the d SPACE-ASM simulation platform to verify the control strategy under more complex conditions.Through simulations of eight different operating conditions,it is proved that the developed yaw stability control strategy can optimize the yaw stability of the vehicle under various operating conditions.Moreover,this control strategy has a particularly obvious effect on the problem of the instability of the rear carriage and the folding of the vehicle body.In summary,the yaw stability control strategy of the multi-wheel distributed driving articulated bus has its feasibility and effectiveness.