METHOD AND SYSTEM OF ANGLE ESTIMATION

• US 20150073744A1
• Filed: 09/06/2013
• Published: 03/12/2015
• Est. Priority Date: 02/04/2013
• Status: Active Grant

• Current Assignee: Jaguar Land Rover Limited (TATA Motors Limited)
• Original Assignee: Jaguar Land Rover Limited (TATA Motors Limited)
• Inventors: Herrera, Juan, Flinders, Mark, Solomon, Nick
• Granted Patent: US 9,534,891 B2
• Time in Patent Office: Days
• US Class Current: 702/141
• CPC Class Codes: B60W 2030/043 about the roll axis
• CPC Class Codes: B60W 2050/0055 High-pass filters
• CPC Class Codes: B60W 2050/0056 Low-pass filters
• CPC Class Codes: B60W 2420/905 the sensor being an xyz axis sensor
• CPC Class Codes: B60W 2520/16 Pitch
• CPC Class Codes: B60W 40/076 Slope angle of the road
• CPC Class Codes: G01B 21/22 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01M 17/06 Steering behaviour; Rolling behaviour
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration

Abstract

A method of angle estimation for use in a vehicle which is travelling on a surface. The vehicle includes a vehicle body having a first axis and being attached to at least two wheels. The method includes the steps of: providing a first height sensor for measuring h₁, the height of the vehicle body with respect to the first wheel; providing a second height sensor for measuring h₂, the height of the vehicle body with respect to the second wheel; providing a surface angle sensor for measuring θ_road, the angle of the surface in relation to a horizontal plane; measuring the values of h₁, h₂ and θ_road; using the values of h₁ and h₂ to calculate θ_rel, the angle of the vehicle body relative to the surface; and calculating an estimate of θ_glob, the angle between the first axis and the horizontal plane, from θ_road and θ_rel.

Claims

1. A method of angle estimation for use in a vehicle which is travelling on a surface, the vehicle comprising a vehicle body which is attached to at least two wheels, the vehicle body having a first axis, the method comprising:

calculating θ

_glob1 as a first estimate of the angle θ

_glob between the first axis and a horizontal plane;

producing θ

_globtransient, an estimate of transient values of θ

_glob, by applying a high pass filter to θ

_glob1;

calculating θ

_globsteady state as an estimate of steady state values of θ

_glob; and

calculating a further estimate of θ

_glob from θ

_globtransient and θ

_globsteady state.

2. A method of angle estimation according to claim 1, the method comprising:

providing a first height sensor for measuring h₁, the height of the vehicle body with respect to the first wheel;

providing a second height sensor for measuring h₂, the height of the vehicle body with respect to the second wheel;

providing a surface angle sensor for measuring θ

_road, the angle of the surface in relation to a horizontal plane;

providing an orientation sensor for measuring θ

_{g{dot over (l)}ob}, θ

_{g{dot over (l)}ob} being the rate of change of θ

_glob with respect to time;

measuring the values of h₁, h₂, θ

_road and θ

_{g{dot over (l)}ob};

calculating θ

_glob1 by integrating θ

_{g{dot over (l)}ob} with respect to time;

producing θ

_globtransient by applying a high pass filter to θ

_glob1;

calculating the angle θ

_rel of the first axis relative to the surface using the values of h₁ and h₂;

calculating θ

_globsteady state by combining θ

_rel and θ

_road and applying at least one low pass filter; and

calculating a further estimate of θ

_glob from θ

_globtransient and θ

_globsteady state.

3. A method of angle estimation according to claim 2, wherein the surface angle sensor comprises an accelerometer for measuring a_x, the acceleration of the vehicle with respect to the first axis.

4. A method of angle estimation for use in a vehicle which is travelling on a surface, the vehicle comprising a vehicle body which is attached to at least two wheels, the vehicle body having a first axis, the method comprising:

providing a first height sensor for measuring h₁, the height of the vehicle body with respect to the first wheel;

providing a second height sensor for measuring h₂, the height of the vehicle body with respect to the second wheel;

providing a surface angle sensor for measuring θ

_road, the angle of the surface in relation to a horizontal plane;

measuring the values of h₁, h₂ and θ

_road;

calculating the angle θ

_rel of the first axis relative to the surface using the values of h₁ and h₂; and

calculating an estimate of θ

_glob, the angle between the first axis and the horizontal plane, from θ

_road and θ

_rel.

5. A method of angle estimation according to claim 4, wherein the surface angle sensor comprises an accelerometer for measuring a_x, the acceleration of the vehicle with respect to the first axis.

6. A method of angle estimation according to claim 5, wherein measuring θ

_road comprises calculating an estimate θ

_road′

, using the relationship;

θ

_road′

=θ

_glob′

−

θ

_rel′

,

wherein θ

_glob′ and

θ

_rel′

are estimates of θ

_glob and θ

_rel.

7. A method of angle estimation according to claim 6, the method comprising calculating θ

_glob′

using the equation;

8. A method of angle estimation according to claim 6, the method comprising calculating θ

_rel′

using the equation;

9. An angle estimation system for use in a vehicle which is travelling on a surface, the vehicle comprising a vehicle body which is attached to at least two wheels, the vehicle body having a first axis, the angle estimation system comprising a control unit, the control unit being arranged to:

calculate θ

_glob1 as a first estimate of the angle θ

_glob between the first axis and a horizontal plane;

apply a high pass filter to θ

_glob1 to produce θ

_globtransient, an estimate of transient values of θ

_glob;

calculate θ

_globsteady state, an estimate of steady state values of θ

_glob; and

calculate a further estimate of θ

_glob from θ

_globtransient and θ

_globsteady state.

10. An angle estimation system according to claim 9, the angle estimation system further comprising:

a first height sensor for measuring h₁, the height of the vehicle body with respect to the first wheel;

a second height sensor for measuring h₂, the height of the vehicle body with respect to the second wheel;

a surface angle sensor for measuring θ

_road, the angle of the surface in relation to a horizontal plane; and

an orientation sensor for measuring θ

_{g{dot over (l)}ob}, θ

_{g{dot over (l)}ob} being the rate of change of θ

_glob with respect to time and θ

_glob being the angle between the first axis and the horizontal plane,

the control unit being arranged to;

receive signals from the sensors indicating the values of h₁, h₂, θ

_road and θ

_{g{dot over (l)}ob};

integrate θ

_{g{dot over (l)}ob} with respect to time to calculate θ

_glob1;

apply a high pass filter to θ

_glob1 to produce θ

_globtransient;

use the values of h₁ and h₂ to calculate θ

_rel, the angle of the first axis relative to the surface;

combine θ

_rel and θ

_road, and apply a low pass filter, to produce θ

_globsteady state; and

calculate a further estimate of θ

_glob from θ

_globtransient and θ

_globsteady state.

11. An angle estimation system according to claim 10, wherein the surface angle sensor comprises an accelerometer for measuring a_x, the acceleration of the vehicle with respect to the first axis.

12. A vehicle comprising an angle estimation system according to claim 9.

13. An angle estimation system for use in a vehicle which is travelling on a surface, the vehicle comprising a vehicle body which is attached to at least two wheels, the vehicle body having a first axis, the angle estimation system comprising:

a first height sensor for measuring h₁, the height of the vehicle body with respect to the first wheel;

a second height sensor for measuring h₂, the height of the vehicle body with respect to the second wheel;

a surface angle sensor for measuring θ

_road, the angle of the surface in relation to a horizontal plane; and

a control unit, the control unit being arranged to;

receive signals from the sensors indicating the values of h₁, h₂ and θ

_road;

use the values of h₁ and h₂ to calculate θ

_rel, the angle of the first axis relative to the surface; and

calculate an estimate of θ

_glob, the angle between the first axis and the horizontal plane, from θ

_road and θ

_rel.

14. An angle estimation system according to claim 13, wherein the surface angle sensor comprises an accelerometer for measuring a_x, the acceleration of the vehicle with respect to the first axis.

15. An angle estimation system according to claim 14, wherein measuring θ

_road comprises calculating an estimate θ

_road′

, using the relationship;

θ

_road′

=θ

_glob′

−

θ

_rel′

,

wherein θ

_glob′ and

θ

_rel′

are estimates of θ

_glob and θ

_rel.

16. An angle estimation system according to claim 15, the control unit being further arranged to calculate θ

_glob′

using the equation;

17. An angle estimation system according to claim 15, the control unit being further arrange to calculate θ

_rel′

using the equation;