Method for road grade/vehicle pitch estimation

• US 6,714,851 B2
• Filed: 01/07/2002
• Issued: 03/30/2004
• Est. Priority Date: 01/07/2002
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Tseng, Hongtei Eric, Hrovat, Davorin David, Brown, Todd Allen
• Primary Examiner(s): Chin, Gary
• Application Number:
  US10/040,806
• Publication Number:
  US 20030130778A1
• Time in Patent Office: 813 Days
• Field of Search: 701/1, 701/45, 701/46, 701/70, 180/282, 280/735, 340/429, 340/440
• US Class Current: 701/70
• CPC Class Codes: B60G 2400/0512 Pitch angle
• CPC Class Codes: B60G 2400/0521 Roll rate
• CPC Class Codes: B60G 2400/0523 Yaw rate
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/106 longitudinal with regard to vehicle, e.g. braking
• CPC Class Codes: B60G 2400/208 of wheel rotation
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2400/412 of steering wheel or column
• CPC Class Codes: B60G 2600/044 Alarm means
• CPC Class Codes: B60G 2600/124 Error signal
• CPC Class Codes: B60G 2800/014 Pitch; Nose dive
• CPC Class Codes: B60G 2800/0192 longitudinal with regard to vehicle
• CPC Class Codes: B60G 2800/212 Transversal; Side-slip during cornering
• CPC Class Codes: B60G 2800/702 Improving accuracy of a sensor signal
• CPC Class Codes: B60G 2800/9124 Roll-over protection systems, e.g. for warning or control
• CPC Class Codes: B60R 16/0233 Vehicle tilting, overturning or roll over
• CPC Class Codes: B60R 2021/01184 Fault detection or diagnostic circuits in power circuits B60R2021/01129
• CPC Class Codes: B60R 2021/01306 monitoring vehicle inclination
• CPC Class Codes: B60R 2021/01327 Angular velocity or angular acceleration
• CPC Class Codes: B60R 21/0132 responsive to vehicle motion parameters , e.g. to vehicle longitudinal or transversal deceleration or speed value
• CPC Class Codes: B60T 2250/06 : Sensor zero-point adjustment; Offset compensation
• 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 2050/0021 : Differentiating means
• CPC Class Codes: B60W 2520/10 : Longitudinal speed
• CPC Class Codes: B60W 2520/105 : Longitudinal acceleration
• CPC Class Codes: B60W 2520/14 : Yaw
• CPC Class Codes: B60W 2520/16 : Pitch
• CPC Class Codes: B60W 2552/15 : Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 30/1819 : Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60W 40/109 : Lateral acceleration
• CPC Class Codes: B60W 40/11 : Pitch movement
• CPC Class Codes: B60W 40/112 : Roll movement
• CPC Class Codes: B60W 40/114 : Yaw movement
• CPC Class Codes: B62D 7/159 : characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

A control system (13) for an automotive vehicle (10) includes a longitudinal accelerometer (24) that generates a longitudinal acceleration signal corresponding to a longitudinal acceleration of a center of gravity (COG) of the vehicle body. A lateral velocity sensor (22) generates a lateral velocity signal corresponding to the lateral velocity of the vehicle body. A controller (14) is coupled to the yaw rate sensor (18), the longitudinal accelerometer (24) and the lateral velocity sensor (22). The controller (14) determines a longitudinal speed from the longitudinal acceleration signal. The controller determines a vehicle pitch angle in response to the longitudinal speed, the yaw rate signal and the lateral velocity signal.

Claims

1. A method of detecting a vehicle pitch angle for use in stability control system for a motor vehicle, said method comprising the steps of:

generating a longitudinal speed signal corresponding to a longitudinal speed of the vehicle;

generating a longitudinal acceleration signal corresponding to a longitudinal acceleration of the vehicle;

generating a derivative signal corresponding to a derivative of said longitudinal speed;

generating a yaw rate signal corresponding to vehicle yaw rate;

generating a lateral velocity signal corresponding to the lateral velocity of the vehicle; and

determining said vehicle pitch angle in response to said derivative signal, said yaw rate signal and said lateral velocity signal.

2. A method as recited in claim 1 wherein said step of determining a vehicle pitch angle is performed in accordance with the equation

3. A method as recited in claim 1 further comprising the step of controlling a safety device in response to said pitch angle.

4. A method of detecting vehicle pitch angle as described in claim 1 further comprising:

determining a pitch estimation error in response to a pre-calibrated function in response to steering wheel angle, vehicle speed, said yaw rate and lateral acceleration.

5. A method of detecting vehicle pitch angle as described in claim 4, wherein said step of determining said pitch estimation error comprises determining said pitch estimation error in response to the expression sinθ

=(a_y/g)·

(v_n/u) where;

u is the longitudinal speed and,

a_x is the longitudinal acceleration, v_n is a lateral velocity estimation error; and

θ

is the vehicle pitch angle.

6. A method of detecting vehicle pitch angle as recited in claim 5, wherein a pitch estimation bound is determined by the equation (a_y/g)·

(v_n/u).

7. A method of detecting a vehicle pitch angle as described in claim 5, further comprising determining an estimated lateral velocity in response to a lateral velocity observer.

8. A method of detecting a vehicle pitch angle as described in claim 7, wherein said step of determining an estimated lateral velocity in response to a lateral velocity observer comprises determining the estimated lateral velocity in response to a vehicle speed, steering wheel angle, said yaw rate and a lateral acceleration.

9. A method of detecting a vehicle pitch angle as described in claim 7, wherein said step of determining an estimated lateral velocity comprises determining a lateral velocity estimation error.

10. A method of detecting a vehicle pitch angle as described in claim 1, further comprising calibrating said longitudinal acceleration signal, yaw rate signal, said lateral velocity signal.

11. A method of detecting a vehicle pitch angle as described in claim 10, wherein said calibrating comprises during a steady state, generating an adjustment signal.

12. A method of detecting a vehicle pitch angle as described in claim 11, wherein said step of generating an adjustment signal comprises deriving an adjustment signal in response to

13. A method of pitch alignment for sensors of an automotive vehicle, said method comprising:

generating a yaw rate signal corresponding to vehicle yaw rate;

generating a roll rate signal corresponding to vehicle roll rate;

generating a lateral acceleration signal corresponding to vehicle lateral acceleration;

determining when the vehicle is operating in a steady state turning condition;

generating a pitch angle alignment θ

when the vehicle is in the steady state turning condition where;

14. A control system for an automotive vehicle having a vehicle body comprising:

a yaw rate sensor generating a yaw motion signal corresponding to a yaw motion of the vehicle body;

a longitudinal accelerometer generating a longitudinal acceleration signal corresponding to a longitudinal acceleration of a center of gravity of the vehicle body;

a lateral velocity sensor generating a lateral velocity signal corresponding to the lateral velocity of the vehicle body; and

a controller coupled to said yaw rate sensor, said longitudinal accelerometer and said lateral velocity sensor, said controller determining a longitudinal speed from said longitudinal acceleration signal, said controller determining a vehicle pitch angle in response to said longitudinal speed, said yaw rate signal and said lateral velocity signal.

15. A control system as recited in claim 14, further comprising a safety system coupled to said controller, said controller generating a control signal to said safety system in response to said vehicle pitch angle.

16. A control system as recited in claim 15, wherein said safety system comprises an active brake control system.

17. A control system as recited in claim 15, wherein said safety system comprises an active rear steering system.

18. A control system as recited in claim 15, wherein said safety system comprises an active front steering system.

19. A control system as recited in claim 15, wherein said safety system comprises an active anti-roll bar system.

20. A control system as recited in claim 15, wherein said safety system comprises an active suspension system.