Method for establishing a release criterion for restraining means

• US 6,453,225 B1
• Filed: 03/01/2001
• Issued: 09/17/2002
• Est. Priority Date: 04/20/1999
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Roelleke, Michael
• Primary Examiner(s): Nguyen, Tan
• Assistant Examiner(s): Tran, Dalena
• Application Number:
  US09/719,877
• Time in Patent Office: 565 Days
• Field of Search: 701/45, 701/46, 701/47, 701/301, 280/734, 280/735, 280/728.1, 180/268, 180/271, 180/282, 340/436, 340/438, 340/903
• US Class Current: 701/45
• 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: B60R 21/0133 by integrating the amplitude of the input signal
• CPC Class Codes: B60R 21/01336 using filtering

Abstract

A clear distinction between deployment and nondeployment situations is made by subjecting the measured acceleration of a vehicle to low-pass filtration, forming a deployment threshold as a function of the filtered acceleration signal, analyzing an acceleration signal, as soon as it is measured, in a first time segment to determine characteristic features indicating a crash event in which the restraint device should not be deployed and reducing the cut-off frequency of the low-pass filter for a predetermined time segment if a nondeployment situation of this type is detected.

Claims

1. A method for forming a deployment criterion for a restrainer in a vehicle, comprising the steps of:

measuring an acceleration signal of the vehicle in at least one direction;

analyzing the acceleration signal, upon measuring the acceleration signal, in a first time segment;

determining a nondeployment event based upon characteristic features indicating a crash event in which the restrainer should not be deployed;

reducing a cut-off frequency of a low-pass filter for a predetermined time segment if a nondeployment event is determined;

filtering the acceleration signal in the low-pass filter, yielding a filtered acceleration signal;

integrating the acceleration signal, yielding an integrated acceleration; and

comparing the integrated acceleration to a deployment threshold, the deployment threshold having a higher value at low accelerations than at high accelerations, the deployment threshold being formed as a function of the filtered acceleration signal.

2. The method according to claim 1 wherein the step of integrating the acceleration signal does not begin until the acceleration signal exceeds a predetermined level.

3. The method according to claim, 1 wherein the low-pass filter is an infinite impulse response filter whose parameters are varied upon determining a nondeployment event so that the filter cut-off frequency is reduced.

4. The method according to claims 1, wherein the low-pass filter is a finite response filter whose parameters are varied upon detecting a nondeployment event so that the filter cut-off frequency is reduced.

5. The method according to claim 1, further comprising the steps of:

integrating the acceleration signal across multiple consecutive, short time windows in the first time segment to detect nondeployment events;

subjecting the integrated signal to a threshold value decision; and

determining a nondeployment event if the integrated signal initially drops below a lower threshold due to a vehicle deceleration and subsequently exceeds an upper threshold due to elastic vibrations in a body of the vehicle.

6. The method according to claim 5, further comprising the steps of:

comparing the integrated signal to a further threshold lower than the lower threshold, the signal only dropping below the further threshold in the case of deployment crashes; and

determining a nondeployment event only if the integrated signal does not drop below the further threshold.