According to the different braking strategies required by different braking conditions,the layered brake-by-wire control strategy was proposed.At the top layer,the residual collision time between the vehicle and the vehicle in front was calculated by the second-order TTC safety collision time model,which was used as basis for the selection of braking strategy.The vehicle two-degree freedom dynamic model,the car body normal force model and the Burckhardt tire model were established at the top layer.At the low level,the braking force was distributed among the wheels.By the sequential quadratic programming(SQP),the vehicle braking force was optimized by establishing an optimization function based on the tire slip rate under general braking,emergency braking and unstable braking conditions,respectively.MATLAB/Simulink and Carsim were used to carry out the joint simulation,and the braking distribution strategy under the three working conditions was verified respectively.The results show that the braking distance and braking time are reduced by respective 18.08％and 25.12％under normal braking conditions,while the braking distance and braking time are reduced by respective 19.17％and 12.79％under emergency braking conditions.Under unstable braking conditions,the proposed strategy can improve the lateral stability of the vehicle through tire differential twist.The proposed braking strategy can significantly improve the braking efficiency of the vehicle.
关键词
线控制动/制动力优化分配/分层控制/序列二次规划方法/ECE法规/制动仿真/滑模控制/碰撞时间
Key words
brake-by-wire/optimal distribution of braking force/layered control/sequential quadratic programming method/ECE regulations/braking simulation/sliding-mode control/collision time
维普
万方数据