A method for quickly judging the linear/nonlinear working state of tire lateral force

Abstract

The invention discloses a quick judgment method for a linear / nonlinear working state of tire lateral force. Based on an existing sensor of an ESP system, whether the tire lateral force is in the nonlinear working state or not is judged quickly by detecting signals of the steering wheel rotating angle, the vehicle traveling speed, the vehicle lateral acceleration, yaw velocity and the like, and intervention criteria are provided for a control system which conducts vehicle stability emergency control through active steering. The quick judgment method comprises the steps that the yaw velocity, the lateral acceleration, the vehicle traveling speed and the steering wheel rotating angle are measured; the pavement adhesion coefficient is estimated; the wheel rotating angle corresponding to the linear / nonlinear critical point of the tire lateral force is calculated; whether the tire lateral force enters a nonlinear region or not is quickly judged; and whether active front wheel steering is intervened or not is quickly judged.

Description

technical field [0001] The invention relates to the field of automobile stability control, especially the active front wheel steering control in the form of superimposed corners under emergency working conditions. Background technique [0002] As an emergency control technology, active front wheel steering adjusts the tire lateral force by superimposing the steering angle on the basis of the driver's steering input, thereby improving the handling stability of the vehicle. At present, this technology has been successfully applied in BMW 5 series and other vehicles, becoming another effective stability control technology after ESP. [0003] However, it is worth noting that active front wheel steering is a stability control technology in emergency situations, and the timing of its intervention will affect the performance of the control technology. Specifically, if the active steering intervenes too early, the vehicle stability margin is large at this time, and the active super...

AI Technical Summary

Problems solved by technology

Specifically, if the active steering intervenes too early, the vehicle stability margin is large at this time, and the active superposition of corners may cause conflicts with the driver's driving intentions, causing driver discomfort; if the active steering intervenes too late, the vehicle stability will be sacrificed. Sexual control effect, it is difficult to ensure the stability and safety of the vehicle

At the same time, existing studies have shown that the yaw moment adjustment range of ESP and other longitudinal force stability control methods is wider than that of active steering. Therefore, the mature ESP stability intervention criteria are not suitable for active front wheel steering and cannot be directly transplanted. Active Front Steering Control

[0004] image 3 The "lateral force-slip angle" curve of the tire shown shows that the lateral force of the OA section of the tire has a linear relationship with the slip angle. The AB section is a non-linear interval. Although increasing the tire slip angle can increase the tire lateral force, it is obvious that the increase speed of the lateral force slows down and reaches saturation at point B, and the increase of the lateral force will increase by a large margin. Tire slip angle is at the cost; point B is backward, and the side force of the tire cannot be improved by adjusting the side slip angle

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