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

• US 7,797,125 B2
• Filed: 01/24/2006
• Issued: 09/14/2010
• Est. Priority Date: 03/11/2005
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Golombeck, Marc-Andre, Doerr, Alfons, Schmid, Michael
• Primary Examiner(s): BHAT, ADITYA S
• Application Number:
  US11/885,924
• Publication Number:
  US 20080275664A1
• Time in Patent Office: 1,694 Days
• Field of Search: 702/141
• US Class Current: 702/141
• CPC Class Codes: B60G 2400/0511 Roll angle
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/082 Sensor drift
• CPC Class Codes: B60G 2800/0124 Roll-over conditions
• CPC Class Codes: B60G 2800/702 Improving accuracy of a sensor signal
• CPC Class Codes: B60G 2800/80 Detection or control after a system or component failure
• CPC Class Codes: B60G 2800/9124 Roll-over protection systems, e.g. for warning or control
• CPC Class Codes: B60G 2800/925 Airbag deployment systems
• CPC Class Codes: B60R 2021/0018 Roll-over
• CPC Class Codes: B60R 2021/0119 Plausibility check
• CPC Class Codes: B60R 2021/01327 Angular velocity or angular acceleration
• CPC Class Codes: B60R 21/01332 by frequency or waveform analysis
• CPC Class Codes: B60R 21/0134 responsive to imminent contact with an obstacle , e.g. using radar systems
• CPC Class Codes: B60W 2050/0215 Sensor drifts or sensor failures
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/18 Roll
• CPC Class Codes: B60W 50/0205 Diagnosing or detecting failures; Failure detection models

Abstract

A method for determining the roll angle for occupant protection devices and a corresponding device are described. A transverse acceleration and a vertical acceleration of the vehicle are detected, and the roll angle of the vehicle is estimated based on the detected transverse acceleration and the detected vertical acceleration.

Claims

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

detecting, by a processor, a transverse acceleration (a_y) and a vertical acceleration (a_z) of the vehicle; and

estimating, by the processor, the roll angle (α

) of the vehicle based on the detected transverse acceleration (a_y) and the detected vertical acceleration (a_z);

wherein the estimating includes comparing the detected transverse acceleration (a_y) to a first threshold value and comparing the detected vertical acceleration (a_z) to a second threshold value, the roll angle (α

) being estimated using a first approximation when the transverse acceleration (a_y) is greater than the first threshold value and the vertical acceleration (a_z) is greater than the second threshold value, and the roll angle (α

) being estimated using a second approximation when at least one of the transverse acceleration (a_y) is less than or equal to the first threshold value and the vertical acceleration (a_z) is less than or equal to the second threshold value, and

wherein trigonometric functions for estimating the roll angle ({acute over (α

)}) are approximated by corresponding Taylor series expansions, a sine function of the roll angle ({acute over (α

)}) being approximated according to sin {acute over (α

)}≈

{acute over (α

)}+o(á

²) for the first and second approximations, a cosine function of the roll angle ({acute over (α

)}) being approximated according to cos {acute over (α

)}≈

1−

{acute over (α

)}²/2+o({acute over (α

)}⁴) for the first approximation and being approximated according to cos {acute over (α

)}≈

1+o({acute over (α

)}²) for the second approximation.

2. The method as recited in claim 1, wherein the estimated roll angle (α

) is compared to a limit angle, an error flag being set when the estimated roll angle (α

) exceeds the limit angle and the estimated roll angle (α

) being output otherwise.

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

) is estimated in the first approximation according to the equation

${\mathrm{\alpha <br><br>}}_{1/2}=\frac{\begin{array}{c}-\left(\frac{v^2}{r}*a_z+g*a_z\right)\pm <br><br>\\ \sqrt{{\left(\frac{v^2}{r}*a_y+g*a_z\right)}^2+2*{\left(\frac{v^2}{r}*a_z-g*a_y\right)}^2}\end{array}}{\left(\frac{v^2}{r}*a_z-g*a_y\right)}<br><br>.$

4. The method as recited in claim 3, wherein a centripetal acceleration

$\left(\frac{v^2}{r}\right)$

is calculated according to an equation

$\frac{v^2}{r}=\pm$

a y 2 + a z 2 - g 2 ⁢

.

5. The method as recited in claim 3, wherein the roll angle (α

) is estimated in the second approximation according to an equation

${\mathrm{\alpha <br><br>}}_{1/2}=\frac{-a_y\pm <br><br>\sqrt{a_y^2-4*g*\left(g-a_z\right)}}{2*g}<br><br>.$

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

) is estimated in the first approximation according to the equation

${\mathrm{\alpha <br><br>}}_{1/2}=\frac{\begin{array}{c}-\left(\frac{v^2}{r}-g\right)\mp <br><br>\\ \sqrt{{\left(\frac{v^2}{r}-g\right)}^2+2*\left(\frac{v^2}{r}+g\right)*\left(g+\frac{v^2}{r}-a_y-a_z\right)}\end{array}}{\left(\frac{v^2}{r}+g\right)}<br><br>.$

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

) is estimated in the first approximation according to the equation

$\mathrm{\alpha <br><br>}=\frac{-a_y*g+a_z*\frac{v^2}{r}}{g^2+{\left(\frac{v^2}{r}\right)}^2}<br><br>.$

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

a first acceleration sensor adapted to detect a transverse acceleration (a_y) of a vehicle;

a second acceleration sensor adapted to detect a vertical acceleration (a_z) of the vehicle; and

an analyzer unit adapted to estimate the roll angle (α

) of the vehicle based on the detected transverse acceleration (a_y) and the detected vertical acceleration (a_z),

wherein the analyzer unit is adapted to compare the transverse acceleration (a_y) to a first threshold value and the vertical acceleration (a_z) to a second threshold value and, depending on results of the comparison, estimate the roll angle (α

) using a first approximation or using a second approximation, and

wherein trigonometric functions for estimating the roll angle ({acute over (α

)}) are approximated by corresponding Taylor series expansions, a sine function of the roll angle ({acute over (α

)}) being approximated according to sin {acute over (α

)}≈

{acute over (α

)}+o(á

²) for the first and second approximations, a cosine function of the roll angle ({acute over (α

)}) being approximated according to cos {acute over (α

)}≈

1−

{acute over (α

)}²/2+o({acute over (α

)}⁴) for the first approximation and being approximated according to cos {acute over (α

)}≈

1+o({acute over (α

)}²) for the second approximation.