Active brake control including estimation of yaw rate and slip angle
First Claim
1. 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.
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Accused Products
Abstract
An improved vehicle active brake control based on an estimate of vehicle yaw rate and slip angle, wherein the estimate is based on a weighted average of two yaw rate values developed with two different estimation techniques. In general, the first estimate of yaw rate is based on the relative velocity of the un-driven wheels, and the second estimate is based on a measure of lateral acceleration. Confidence levels in each estimate are determined and used to form a third or preliminary yaw rate estimate based on a weighted average of the first and second estimates, and the third estimate is supplied to a closed-loop nonlinear dynamic observer which develops the final estimate of yaw rate, along with estimates of lateral velocity and side-slip angle.
134 Citations
16 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. 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:
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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; and 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 closed-loop non-linear dynamic observer includes gain terms applied to a difference between said preliminary estimate of yaw rate and said final estimate of yaw rate, and the method includes the steps of; determining an overall confidence level according to the sum of said first and second confidence levels; and adjusting said gain terms in proportion to the determined overall confidence.
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Specification