ESTIMATING VEHICLE VELOCITIES USING LINEAR-PARAMETER-VARYING AND GAIN VARYING SCHEDULING THEORIES

• US 20030163226A1
• Filed: 02/25/2002
• Published: 08/28/2003
• Est. Priority Date: 02/25/2002
• Status: Active Grant

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Tan, Hualin
• Granted Patent: US 6,618,651 B1
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: B60T 2250/04 Vehicle reference speed; Vehicle body speed
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60W 2050/0022 Gains, weighting coefficients or weighting functions
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/105 Longitudinal acceleration
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60W 40/105 Speed

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.

Claims

1. A method for estimating longitudinal and lateral velocities in a motor vehicle comprising the steps of:

sensing lateral acceleration, A_x, on the motor vehicle;

sensing longitudinal acceleration A_y, 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;

$\begin{array}{cc}\begin{array}{c}{L}_1=<br><br>2<br><br>\mathrm{\lambda <br><br>}\\ L_2=<br><br>\frac{{\mathrm{\lambda <br><br>}}^2}{{\mathrm{\Psi <br><br>}}_L}-\mathrm{\Psi <br><br>},\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Psi <br><br>}}_L=\{\begin{array}{c}\mathrm{\Psi <br><br>},<br><br>\text{\hspace{1em}<br><br>}\\ {\mathrm{\Psi <br><br>}}_{0<br><br>\text{\hspace{1em}<br><br>}}<br><br>\mathrm{sign}<br><br>\left(\mathrm{\Psi <br><br>}\right),<br><br>\text{\hspace{1em}<br><br>}\end{array}<br><br>\begin{array}{c}\mathrm{for}\left|\mathrm{\Psi <br><br>}\right|\ge <br><br>{\mathrm{\Psi <br><br>}}_0\\ \mathrm{for}\left|\mathrm{\Psi <br><br>}\right|<<br><br>{\mathrm{\Psi <br><br>}}_0\end{array}\end{array}& 2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>3\end{array}$

where λ

is a positive constant, Ψ

o 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;

$\begin{array}{cc}\left[\begin{array}{c}\frac{<br><br>{\hat{V}}_x}{<br><br>t}\\ \frac{<br><br>{\hat{V}}_y}{<br><br>t}\end{array}\right]=\left[\begin{array}{cc}0& \mathrm{\Psi <br><br>}\\ -\mathrm{\Psi <br><br>}& 0\end{array}\right]<br><br>\left[\begin{array}{c}{\hat{V}}_x\\ {\hat{V}}_y\end{array}\right]+\left[\begin{array}{c}{L}_1\\ L_2\end{array}\right]<br><br>\left(Y_m-\left[\begin{array}{cc}1& 0\end{array}\right]<br><br>\left[\begin{array}{c}{\hat{V}}_x\\ {\hat{V}}_y\end{array}\right]\right)+\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]<br><br>\left[\begin{array}{c}{A}_x\\ A_y\end{array}\right]& 1\end{array}$

where Ym is a signal representing a measurement of the longitudinal wheel velocity.

2. The method as claimed in claim 1 wherein Ym is calculated from wheel velocity information sensed on the motor vehicle.

3. The method as claimed in claim 1 further comprising the step of tuning Ψ

o and λ

according to attributes specific to the motor vehicle, specifications specific to sensors and a status of vehicle dynamics of the motor vehicle.

4. The method as claimed in claim 1 further comprising the steps of:

filtering noise from the sensed lateral acceleration, longitudinal acceleration and yaw rate; and

offset compensating the sensed lateral acceleration, longitudinal acceleration and yaw rate.

5. 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;

$\begin{array}{cc}\begin{array}{c}{L}_1=<br><br>2<br><br>\mathrm{\lambda <br><br>}\\ L_2=<br><br>\frac{{\mathrm{\lambda <br><br>}}^2}{{\mathrm{\Psi <br><br>}}_L}-\mathrm{\Psi <br><br>},\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Psi <br><br>}}_L=\{\begin{array}{c}\mathrm{\Psi <br><br>},<br><br>\text{\hspace{1em}<br><br>}\\ {\mathrm{\Psi <br><br>}}_{0<br><br>\text{\hspace{1em}<br><br>}}<br><br>\mathrm{sign}<br><br>\left(\mathrm{\Psi <br><br>}\right),<br><br>\text{\hspace{1em}<br><br>}\end{array}<br><br>\begin{array}{c}\mathrm{for}\left|\mathrm{\Psi <br><br>}\right|\ge <br><br>{\mathrm{\Psi <br><br>}}_0\\ \mathrm{for}\left|\mathrm{\Psi <br><br>}\right|<<br><br>{\mathrm{\Psi <br><br>}}_0\end{array}\end{array}& 2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>3\end{array}$

where λ

is a positive constant, Ψ

o 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;

$\begin{array}{cc}\left[\begin{array}{c}\frac{<br><br>{\hat{V}}_x}{<br><br>t}\\ \frac{<br><br>{\hat{V}}_y}{<br><br>t}\end{array}\right]=\left[\begin{array}{cc}0& \mathrm{\Psi <br><br>}\\ -\mathrm{\Psi <br><br>}& 0\end{array}\right]<br><br>\left[\begin{array}{c}{\hat{V}}_x\\ {\hat{V}}_y\end{array}\right]+\left[\begin{array}{c}{L}_1\\ L_2\end{array}\right]<br><br>\left(Y_m-\left[\begin{array}{cc}1& 0\end{array}\right]<br><br>\left[\begin{array}{c}{\hat{V}}_x\\ {\hat{V}}_y\end{array}\right]\right)+\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]<br><br>\left[\begin{array}{c}{A}_x\\ A_y\end{array}\right]& 1\end{array}$

where Ym is a signal representing a measurement of the longitudinal wheel velocity.

6. The system as claimed in claim 5 further comprising a signal processor for filtering noise and performing offset compensation of signals sensed by said plurality of sensors.

7. 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;

$\begin{array}{cc}\begin{array}{c}{L}_1=<br><br>2<br><br>\mathrm{\lambda <br><br>}\\ L_2=<br><br>\frac{{\mathrm{\lambda <br><br>}}^2}{{\mathrm{\Psi <br><br>}}_L}-\mathrm{\Psi <br><br>},\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Psi <br><br>}}_L=\{\begin{array}{c}\mathrm{\Psi <br><br>},<br><br>\text{\hspace{1em}<br><br>}\\ {\mathrm{\Psi <br><br>}}_{0<br><br>\text{\hspace{1em}<br><br>}}<br><br>\mathrm{sign}<br><br>\left(\mathrm{\Psi <br><br>}\right),<br><br>\text{\hspace{1em}<br><br>}\end{array}<br><br>\begin{array}{c}\mathrm{for}\left|\mathrm{\Psi <br><br>}\right|\ge <br><br>{\mathrm{\Psi <br><br>}}_0\\ \mathrm{for}\left|\mathrm{\Psi <br><br>}\right|<<br><br>{\mathrm{\Psi <br><br>}}_0\end{array}\end{array}& 2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{and}<br><br>\text{\hspace{1em}<br><br>}<br><br>3\end{array}$

where λ

is a positive constant, Ψ

o is a positive constant, and “

sign”

represents the sign of the way rate;

tuning Ψ

o 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;

$\begin{array}{cc}\left[\begin{array}{c}\frac{<br><br>{\hat{V}}_x}{<br><br>t}\\ \frac{<br><br>{\hat{V}}_y}{<br><br>t}\end{array}\right]=\left[\begin{array}{cc}0& \mathrm{\Psi <br><br>}\\ -\mathrm{\Psi <br><br>}& 0\end{array}\right]<br><br>\left[\begin{array}{c}{\hat{V}}_x\\ {\hat{V}}_y\end{array}\right]+\left[\begin{array}{c}{L}_1\\ L_2\end{array}\right]<br><br>\left(Y_m-\left[\begin{array}{cc}1& 0\end{array}\right]<br><br>\left[\begin{array}{c}{\hat{V}}_x\\ {\hat{V}}_y\end{array}\right]\right)+\left[\begin{array}{cc}1& 0\\ 0& 1\end{array}\right]<br><br>\left[\begin{array}{c}{A}_x\\ A_y\end{array}\right]& 1\end{array}$

where Ym is a signal representing a measurement of the longitudinal wheel velocity.