Abstract: The study on vehicle ranging is a hot research direction in the field of driving today,and aiming at the problems that the ranging accuracy of traditional ranging methods is affected by the size of the model and the X-axis offsetof the vehicle in front,a vehicle ranging model based on the center point of the lower edge of the detection frame is proposed.The model uses a monocular vision camera and vehicle detection algorithm to obtain the position information of the vehicle in front,and establishes a vehicle ranging model by comprehensively establishing the vehicle ranging model through the coordinates of the center point of the lower edge obtained by the vehicle detection frame and the pitch angle information installed by the camera,which solves the error problem caused by the size of the model,and solves the problem of X-axis component of the preceding vehicle relative to the experimental vehicle by constructing the trigonometric model,and optimizes and improves the determination method of the safety distance of the preceding vehicle.At the same time,the ratio λ of the abscissa of the center point of the rear rectangular frame to the width of the external rectangular frame of the vehicle is set,and the situation is discussed according to the λ value,so that the model is more in line with the needs of scene applications.An inverse perspective transformation model based on the key points of ranging is proposed to reduce the ranging error.Experiments show that the ranging accuracy of the improved ranging model is not affected by the size of the model and can take into account the X-axis component of the front vehicle position,and the ranging error of the improved ranging model is reduced by about 1.5% compared with the traditional ranging model,and the ranging accuracy of the improved ranging method is significantly improved.

Key words: Monocular vision, Ranging, Inverse perspective transformation, Center point of the lower edge of detection box, Object detection