Estimating vehicle velocities using linear-parameter-varying and gain varying scheduling theories
AssigneeVisteon Global Technologies, Inc.
InventorHualin Tan
Life of this patent
Estimating the term…
Abstract
A system and a method for dynamically estimating the vehicle longitudinal and lateral velocities based on information gathered from four sensors measuring the longitudinal acceleration, lateral acceleration, wheel speed and yaw rate. The present invention provides a linear-parameter-varying state observer in conjunction with a gain scheduled state observer to provide good estimation of the vehicle motion in linear and non-linear ranges. The present invention is not dependent on variations in vehicle parameters, requires low computing power, and achieves improved estimation by adjusting the observer gains according to the changing yaw rate.
Claims7
A method for estimating longitudinal and lateral velocities in a motor vehicle comprising the steps of:
- sensing lateral acceleration, Ax, on the motor vehicle;
- sensing longitudinal acceleration Ay, on the motor vehicle;
- sensing yaw rate, Ψ, on the motor vehicle;
- determining time-varying gains, L1 and L2, according to the sensed yaw rate and the following formulas;
- L 1 = 2 λ L 2 = λ 2 Ψ L - Ψ , Ψ L = { Ψ , for [LeftBracketingBar] Ψ [RightBracketingBar] ≥ Ψ 0 Ψ 0 sign ( Ψ ) for [LeftBracketingBar] Ψ [RightBracketingBar] < Ψ 0 2 and 3
- where λ is a positive constant, Ψo is a positive constant, and “sign” represents the sign of the way rate;
- determining estimates of the lateral velocity, V′x and the longitudinal velocity V′y, in accordance with the following equation;
- [ ⅆ V ^ x ⅆ t ⅆ V ^ y ⅆ t ] = [ 0 Ψ - Ψ 0 ] [ V ^ x V ^ y ] + [ L 1 L 2 ] ( Y m - [ 1 0 ] [ V ^ x V ^ y ] ) + [ 1 0 0 1 ] [ A x A y ] 1
- where Ym is a signal representing a measurement of the longitudinal wheel velocity.
A system for estimating vehicle lateral velocity and longitudinal velocity comprising:
- a plurality of sensors attached to a vehicle for sensing predetermined vehicle parameters including lateral acceleration, Ax, longitudinal acceleration, Ay and yaw rate, Ψ;
- a microcontroller in electrical communication with said plurality of sensors, said microcontroller being operative to:
- determine time-varying gains, L1 and L2, according to the sensed yaw rate and the following formulas;
- L 1 = 2 λ L 2 = λ 2 Ψ L - Ψ , Ψ L = { Ψ , for [LeftBracketingBar] Ψ [RightBracketingBar] ≥ Ψ 0 Ψ 0 sign ( Ψ ) for [LeftBracketingBar] Ψ [RightBracketingBar] < Ψ 0 2 and 3
- where λ is a positive constant, Ψo is a positive constant, and “sign” represents the sign of the way rate;
- and
- determine estimates of the lateral velocity, V′x and the longitudinal velocity V′y, in accordance with the following equation;
- [ ⅆ V ^ x ⅆ t ⅆ V ^ y ⅆ t ] = [ 0 Ψ - Ψ 0 ] [ V ^ x V ^ y ] + [ L 1 L 2 ] ( Y m - [ 1 0 ] [ V ^ x V ^ y ] ) + [ 1 0 0 1 ] [ A x A y ] 1
- where Ym is a signal representing a measurement of the longitudinal wheel velocity.
A method for estimating longitudinal and lateral velocities in a motor vehicle comprising the steps of:
- sensing lateral acceleration, Ax, on the motor vehicle;
- sensing longitudinal acceleration Ay, on the motor vehicle;
- sensing yaw rate, Ψ, on the motor vehicle;
- filtering noise from the sensed lateral acceleration, longitudinal acceleration and yaw rate;
- and
- offset compensating the sensed lateral acceleration, longitudinal acceleration and yaw rate;
- determining time-varying gains, L1 and L2, according to the sensed yaw rate and the following formulas;
- L 1 = 2 λ L 2 = λ 2 Ψ L - Ψ , Ψ L = { Ψ , for [LeftBracketingBar] Ψ [RightBracketingBar] ≥ Ψ 0 Ψ 0 sign ( Ψ ) for [LeftBracketingBar] Ψ [RightBracketingBar] < Ψ 0 2 and 3
- where λ is a positive constant, Ψo is a positive constant, and “sign” represents the sign of the way rate;
- tuning Ψo and λ according to attributes specific to the motor vehicle, specifications specific to sensors and a status of vehicle dynamics of the motor vehicle;
- determining estimates of the lateral velocity, V′x and the longitudinal velocity V′y, in accordance with the following equation;
- [ ⅆ V ^ x ⅆ t ⅆ V ^ y ⅆ t ] = [ 0 Ψ - Ψ 0 ] [ V ^ x V ^ y ] + [ L 1 L 2 ] ( Y m - [ 1 0 ] [ V ^ x V ^ y ] ) + [ 1 0 0 1 ] [ A x A y ] 1
- where Ym is a signal representing a measurement of the longitudinal wheel velocity.
Dependencies are inferred from the claim text.