Active brake control including estimation of yaw rate and slip angle

A method of estimating vehicle yaw rate in a vehicle stability enhancement control configured to produce a corrective vehicle yaw moment based on a deviation of the vehicle yaw rate from a desired value, where the vehicle has a pair of undriven wheels, the method comprising the steps of:

• measuring speeds of the undriven wheels of the vehicle;
• measuring a lateral acceleration of the vehicle;
• measuring a vehicle steering angle;
• determining a preliminary estimate of yaw rate of the vehicle based on the measured speeds and the measured lateral acceleration;
• estimating a final yaw rate and lateral velocity with a closed-loop non-linear dynamic observer, wherein the measured lateral acceleration and the preliminary estimate of yaw rate are provided as closed-loop feedback inputs to the dynamic observer;
• wherein the step of determining a preliminary estimate of yaw rate of the vehicle comprises the steps of:
• estimating a first yaw rate of the vehicle based on the measured wheel speeds;
• determining a first confidence level indicative of an accuracy of said first yaw rate estimate;
• estimating a second yaw rate of the vehicle based on the measured lateral acceleration;
• determining a second confidence level indicative of an accuracy of said second yaw rate estimate;
• computing the preliminary yaw rate estimate based on a weighted average of said first and second yaw rate estimates, the first and second confidence levels determining the weights given to the first and second yaw rate estimates.