Method for suppressing deployment of an inflatable restraint based on sensed occupant weight

• US 20030149517A1
• Filed: 02/04/2002
• Published: 08/07/2003
• Est. Priority Date: 02/04/2002
• Status: Active Grant

• Current Assignee: Aptiv Technologies Limited (Aptiv PLC)
• Original Assignee: Delphi Technologies, Inc. (Aptiv PLC)
• Inventors: Murphy, Morgan D., Schubert, Peter J., Rennaker, Royce L., Hall, Brett A., Sullivan, Stuart S., Kaltenbacher, Phillip E. II
• Granted Patent: US 6,850,825 B2
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/01522 using fluid means
• CPC Class Codes: B60R 21/0155 sensing belt tension

Abstract

An improved method of selectively suppressing deployment of a vehicular inflatable restraint utilizes dynamic variation in the apparent weight of a vehicle occupant to infer a free mass of the seat occupant. The free mass of the occupant is inferred by filtering out portions of a weight-responsive signal due to occupant position adjustment and inferring the occupant free mass based on the variation of the apparent weight with respect to the variation in vertical acceleration of the vehicle. The decision to allow or suppress deployment of the restraint is determined based on a comparison of the static weight reading with at least one threshold, and the occupant free mass is used to adjust the threshold in a direction to minimize the overall variability of the system. Measures of the seat belt tension and the seat temperature are also be used to adjust the threshold in a direction to minimize system variability.

Claims

1. A method of determining whether to allow or suppress deployment of a vehicular inflatable restraint for a vehicle occupant based at least in part on an output signal of a sensor responsive to occupant weight applied to a vehicle seat, the method comprising the steps of:

comparing a filtered version of said output signal to a threshold having a default value corresponding to a predetermined occupant weight under a given set of conditions;

determining a value of a parameter that affects a magnitude of said output signal;

adjusting said threshold above or below said default value when the determined parameter value is outside a predetermined range of values; and

allowing deployment of said restraint when the filtered version of said output signal is above said threshold, and suppressing deployment of said restraint when the filtered version of said output signal is below said threshold.

2. The method of claim 1 wherein said parameter is a free mass of the vehicle occupant, the method including the steps of:

measuring a vertical acceleration of the vehicle;

determining a value of said free mass based on a variation of said output signal with respect to a variation of the measured vertical acceleration;

adjusting said threshold below said default value when the determined value of said free mass is above a predetermined range of free mass values corresponding to an average weight occupant; and

adjusting said threshold above said default value when the determined value of said free mass is below the predetermined range of free mass values.

3. The method of claim 2, wherein the step of determining a value of said free mass includes the steps of:

sampling output signal values and computing an average of the sampled values;

identifying sampled output signal values that are within a specified percentage of said average;

computing a first variance of the identified output signal values;

computing a second variance of the measured vertical acceleration; and

determining the value of free mass according to a ratio of the first variance and the second variance.

4. The method of claim 2, including the steps of:

measuring a vehicle run time; and

delaying the step of determining the value of said free mass until the measured run time reaches a predetermined threshold.

5. The method of claim 1, wherein said vehicle seat is equipped with a seat belt for restraining said occupant, and said parameter is a tension of said seat belt, the method including the steps of:

measuring the tension of said seat belt; and

adjusting said threshold above said default value when the measured tension is above a predetermined normal range.

6. The method of claim 1, wherein said parameter is a temperature of said vehicle seat, the method including the steps of:

measuring said temperature; and

adjusting said threshold below said default value when the measured temperature is below a predetermined normal range.