Method enabling rapid and reliable triggering of vehicle occupant restraint systems by spectral frequency analysis of the acceleration signal

• US 5,790,404 A
• Filed: 12/14/1995
• Issued: 08/04/1998
• Est. Priority Date: 12/22/1994
• Status: Expired due to Term

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated), Robert Bosch GmbH
• Original Assignee: Morton International Incorporated (Autoliv Incorporated), Robert Bosch GmbH
• Inventors: Henne, Ralf, Faye, Ian C.
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US08/572,840
• Time in Patent Office: 964 Days
• Field of Search: 364/424.055, 364/424.056, 364/424.057, 364/485, 364/553, 364/566, 364/576, 280/735, 340/436, 340/429, 180/282, 307/10.1
• US Class Current: 701/45
• CPC Class Codes: B60R 2021/01322 comprising variable thresholds, e.g. depending from other collision parameters
• 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 21/01334 using Fourier analysis

Abstract

Triggering reliably within an extremely short time restraining features, for example, air bags, belt retractors, and other devices, that are provided in motor vehicles to offer a maximum degree of safety to vehicle occupants in the event of an accident, in which an acceleration signal is measured and converted into a speed signal by an integration over time and the speed signal is compared with a triggering threshold in order to determine a triggering criterion, wherein there is a provision for the integration of the acceleration signal (a) to be influenced as a function of a frequency analysis of the acceleration signal (a), wherein the acceleration signal is subjected to a spectral frequency analysis which influences a speed of the integration of the acceleration signal (a), and wherein the frequency analysis is carried out by utilizing a fast Fourier transformation (or the suboperations required from it).

Claims

1. A method for triggering a passive restraint system, comprising the steps of:

measuring an acceleration signal having a frequency spectrum;

performing a spectral frequency analysis upon said signal; and

integrating said acceleration signal over time to produce a speed signal, the speed of said integration being varied as a result of said spectral frequency analysis; and

comparing said speed signal to a triggering threshold and producing an activation signal if said speed signal exceeds said threshold;

wherein said step of performing a spectral frequency analysis includes at least a portion of a fast Fourier transformation, and

wherein said step of performing a spectral frequency analysis is repeated at prescribed time increments, and said portion of a fast Fourier transformation is performed using said acceleration signal at a predetermined number of preceding ones of said time increments.

2. A method as in claim 1, wherein at each time increment n, the preceding 2ⁿ ones of said time increments are transformed.

3. A method as in claim 1, wherein said step of performing a transformation produces amplitudes A(f) of selected frequencies within said acceleration signal.

4. A method as in claim 3, wherein said step of performing a spectral frequency analysis further includes differentiating two of said amplitudes A(f), and further, wherein said integration step is accelerated when the result of said differentiation is greater than 1, and said integration step is slowed when the result of said differentiation is less than 1.