| Vehicle active collision avoidance system can avoid or reduce the occurrence of vehicle collision accidents and improve driving safety.In view of the complex vehicle driving environment,it is often encountered that the road adhesion coefficient changes due to the weather turned to rain.In this kind of driving scene,the safety of vehicle active obstacle avoidance will be greatly affected.In order to improve the safety of vehicle obstacle avoidance,a driving risk field model considering the influence of road adhesion coefficient is established in this paper,and based on this model,the vehicle lateral obstacle avoidance path is planned.At the same time,the vehicle active collision avoidance system considering the influence of road adhesion coefficient is studied.The main contents are as follows:(1)The driving risk field model considering the influence of road adhesion coefficient is established.The driving risk field consists of target gravitational field,road boundary risk field and obstacle repulsive force risk field.Taking the negative gradient direction of the driving risk field as the reference path of the lateral obstacle avoidance system of the vehicle active collision avoidance system,the risk value of the path decreases the fastest and the safety of obstacle avoidance is the highest.The effectiveness of vehicle lateral obstacle avoidance path planning based on traffic risk field is proved by simulation experiments.(2)A three-degree-of-freedom vehicle dynamics model and Dugoff tire model were established,and combined with the extended Kalman filter algorithm principle,a road adhesion coefficient recognition algorithm based on EKF was proposed.The Matlab&Car Sim co-simulation model was built and the simulation scenarios of high adhesion,low adhesion and variable adhesion were used to verify the algorithm,and the effectiveness of the proposed algorithm was proved by experiments.(3)Considering the influence of road adhesion coefficient,the overall obstacle avoidance strategy of vehicle active collision avoidance system is designed.Based on feedforward feedback and PID control principle,the horizontal and longitudinal control algorithms of vehicle active collision avoidance system are designed respectively.Based on the horizontal and vertical control algorithms,corresponding simulation verification models are built respectively,and the effectiveness of the designed horizontal and vertical control algorithms for path tracking is proved by experiments.(4)The co-simulation platform and model of Matlab&Car Sim&Pre Scan were built,and static and dynamic simulation scenes were designed to verify the algorithm.The test results show that considering the influence of road adhesion coefficient on the vehicle active obstacle avoidance system,not only can ensure the safety of the vehicle active obstacle avoidance system,but also can improve the adaptability of the vehicle active collision avoidance system to sudden changes in the driving road environment.Different vehicles on different road surfaces take different obstacle avoidance paths for tracking control.Under the premise of ensuring the safety of obstacle avoidance,too conservative or too radical active obstacle avoidance behaviors brought by taking fixed obstacle avoidance paths can be avoided,which plays a positive role in improving drivers’ recognition of active obstacle avoidance system and promoting vehicle active obstacle avoidance technology. |
