Kinematic-based method of estimating the absolute roll angle of a vehicle body
First Claim
1. A method of operation for a vehicle having a body that rolls about a longitudinal axis relative to a level ground plane, comprising the steps of:
- determining a first preliminary estimate of a total roll angle of the vehicle body based on a signal produced by a roll rate sensor, said first preliminary estimate having an accuracy that is highest under transient conditions when a roll rate of the vehicle body is relatively high;
determining a second preliminary estimate of the total roll angle based on a measured yaw rate of the vehicle body, an estimated longitudinal velocity of the vehicle body and a measured lateral acceleration of the vehicle body, said second preliminary estimate having an accuracy that is highest under near steady-state conditions when the roll rate of the vehicle body is relatively low;
blending the first and second preliminary estimates of the total roll angle with blending coefficients to form a blended estimate of the total roll angle, where the blending coefficients are continuously variable according to a frequency of said first and second preliminary estimates so that the blended estimate favors the first preliminary estimate under the transient conditions and the second preliminary estimate under the near steady-state conditions; and
controlling a vehicle system based on the blended estimate of the total roll angle.
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Accused Products
Abstract
The absolute roll angle of a vehicle body is estimated by blending two preliminary roll angle estimates based on their frequency so that the blended estimate continuously favors the more accurate of the preliminary roll angle estimates. A first preliminary roll angle estimate based on the measured roll rate is improved by initially compensating the roll rate signal for bias error using roll rate estimates inferred from other measured parameters. And a second preliminary roll angle estimate is determined based on the kinematic relationship among roll angle, lateral acceleration, yaw rate and vehicle speed. The blended estimate of roll angle utilizes a blending coefficient that varies with the frequency of the preliminary roll angle signals, and a blending factor used in the blending coefficient is set to different values depending whether the vehicle is in a steady-state or transient condition.
25 Citations
10 Claims
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1. A method of operation for a vehicle having a body that rolls about a longitudinal axis relative to a level ground plane, comprising the steps of:
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determining a first preliminary estimate of a total roll angle of the vehicle body based on a signal produced by a roll rate sensor, said first preliminary estimate having an accuracy that is highest under transient conditions when a roll rate of the vehicle body is relatively high; determining a second preliminary estimate of the total roll angle based on a measured yaw rate of the vehicle body, an estimated longitudinal velocity of the vehicle body and a measured lateral acceleration of the vehicle body, said second preliminary estimate having an accuracy that is highest under near steady-state conditions when the roll rate of the vehicle body is relatively low; blending the first and second preliminary estimates of the total roll angle with blending coefficients to form a blended estimate of the total roll angle, where the blending coefficients are continuously variable according to a frequency of said first and second preliminary estimates so that the blended estimate favors the first preliminary estimate under the transient conditions and the second preliminary estimate under the near steady-state conditions; and controlling a vehicle system based on the blended estimate of the total roll angle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification