Modern vehicles often incorporate some form of stability control system to ensure that the actual path of the vehicle corresponds to the path intended by the driver, particularly during hard braking and/or steering operations. Such vehicles might also include collision avoidance systems that sense whether an object is within the vehicle's path and then take corrective action accordingly. This corrective action might take the form of alerting the driver or autonomously applying braking and/or steering to reduce the relative velocity between the vehicle and the obstacle.
Prior art systems typically assume that the vehicle can maintain a specified lateral (sideways) and longitudinal (front/back) acceleration, usually within a friction ellipse of about 0.8 g's maximum lateral and 0.9 g's maximum longitudinal for a dry high coefficient road surface. These acceleration values are then used by the system to determine how much braking and steering can be applied while still maintaining suitable fraction between the vehicle and the road.
Under certain conditions, such as rain, snow, etc., the actual maximum lateral and longitudinal acceleration capabilities of the vehicle may be reduced. Accordingly, it is desirable to provide improved emergency braking and steering systems in which tire and road friction characteristics are measured and taken into account. Other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.