Methods and device for determining the roll angle for occupant protection devices

• US 8,185,271 B2
• Filed: 09/26/2006
• Issued: 05/22/2012
• Est. Priority Date: 11/02/2005
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Tichy, Marc A., Schaefers, Andreas
• Primary Examiner(s): Dickson, Paul N
• Assistant Examiner(s): Freedman, Laura
• Application Number:
  US11/989,883
• Publication Number:
  US 20110082614A1
• Time in Patent Office: 2,065 Days
• Field of Search: 180/271, 180/282, 280/734, 280/735, 701/36, 701/45
• US Class Current: 701/45
• CPC Class Codes: B60R 2021/01313 monitoring the vehicle steering system or the dynamic control system
• CPC Class Codes: B60R 2021/01325 Vertical acceleration
• 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: B60W 40/11 Pitch movement
• CPC Class Codes: B60W 40/112 Roll movement
• CPC Class Codes: B60W 40/114 Yaw movement

Abstract

A method and device for determining a roll angle for occupant protection devices. Transverse acceleration and vertical acceleration of a vehicle are detected, and the roll angle of the vehicle is estimated on the basis of the detected lateral acceleration and the detected vertical acceleration, additional driving dynamics quantities, including a vehicle speed, a yaw angle and a float angle being determined, and centripetal acceleration being calculated from these driving dynamics quantities, formula, to improve the estimate of the roll angle.

Claims

1. A method for determining a roll angle for an occupant protection device, comprising:

detecting a transverse acceleration and a vertical acceleration of a vehicle;

estimating the roll angle of the vehicle based on the detected transverse acceleration and the detected vertical acceleration;

ascertaining additional driving dynamics quantities, the additional driving dynamics quantities including a vehicle speed, a yaw angle and a float angle;

calculating a centripetal acceleration from the driving dynamics quantities; and

using the centripetal acceleration to improve the estimate of the roll angle.

2. The method as recited in claim 1, further comprising:

determining at least one of accelerations caused by steering movements and rolling movements caused by road surface irregularities; and

taking into account the at least one of the accelerations caused by steering movements and the rolling movements caused by road surface irregularities as correction factors in ascertaining the transverse acceleration and the vertical acceleration and thus in estimating the roll angle.

3. The method as recited in claim 2, wherein the rolling movement caused by road surface irregularities is considered to be a rotation about an imaginary fulcrum in a normal driving state and is calculated as a first additional transverse acceleration component and as an additional vertical acceleration component.

4. The method as recited in claim 3, wherein the first additional transverse acceleration component Δ

a_y1 is calculated according to an equation Δ

a_y1={dot over (ω

)}_x·

r_z and the additional vertical acceleration component Δ

a_z is calculated according to an equation Δ

a_z=ω

_X²·

r_z, wherein r_z is the radius of rotation about the imaginary fulcrum extending along the z-axis from the imaginary fulcrum to a sensor system for detecting the transverse acceleration and the vertical acceleration, and ω

_x is an angular velocity about the x-axis.

5. The method as recited in claim 4, wherein a steering movement has a fulcrum near a rear axle during a normal driving situation, an acceleration thereby induced being calculated as a second additional transverse acceleration component.

6. The method as recited in claim 5, wherein the second additional transverse acceleration component Δ

a_y2 is calculated according to an equation Δ

a_y2={dot over (ω

)}_z·

r_x, wherein r_x is the radius of rotation about the imaginary fulcrum extending along the x-axis from the imaginary fulcrum to the sensor system for detecting the transverse acceleration and the vertical acceleration, and {dot over (ω

)}_z is a time derivative of an angular velocity about the z-axis.

7. The method as recited in claim 1, wherein the centripetal acceleration

8. The method as recited in claim 7, wherein the transverse acceleration a_y is calculated according to the equation

9. The method as recited in claim 1, wherein the roll angle α

is estimated according to an equation

10. A device for determining a roll angle for an occupant protection device, comprising:

a first acceleration sensor adapted to detect a transverse acceleration of a vehicle;

a second acceleration sensor adapted to detect a vertical acceleration of the vehicle;

at least one additional sensor unit adapted to ascertain and supply additional driving dynamics quantities, including a vehicle velocity, a yaw angle and a float angle; and

an analyzer unit adapted to estimate the roll angle of the vehicle based on the transverse acceleration detected and the vertical acceleration detected, the analyzer unit improving the estimate of the roll angle by calculating a centripetal acceleration from the vehicle velocity, the yaw angle and the float angle quantities.