Vehicle occupant characterization method based on the power spectrum of a seat sensor output signal

• US 20060100761A1
• Filed: 11/08/2004
• Published: 05/11/2006
• Est. Priority Date: 11/08/2004
• Status: Active Grant

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Prieto, Raymundo, Wagner, Steve J.
• Granted Patent: US 7,120,527 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 21/01556 Child-seat detection systems

Abstract

The occupant of a vehicle seat is characterized by computing a power spectrum function of data obtained from a seat sensor such as a pressure sensor in a fluid-filled seat bladder or a frame-mounted vertical accelerometer. The spectrum function is integrated over a specified frequency range, and compared to a threshold value that is calibrated to compensate for vehicle speed related variability. The presence of a cinched child seat is indicated when the threshold is exceeded, and the presence of a normally seated adult is indicated otherwise.

Claims

1. A method of characterizing an occupant of a vehicle seat, comprising the steps of:

sampling an output signal of a sensor affixed to said seat to construct a digital occupant characterization signal;

calculating a power spectrum function of said occupant characterization signal;

integrating said power spectrum function over a specified frequency range to form an integration value;

retrieving a calibrated threshold based on measure of vehicle speed; and

comparing said integration value to said calibrated threshold and characterizing said occupant based on such comparison.

2. The method of claim 1, including the step of:

removing a DC component of the sampled output signal so that said digital occupant characterization signal represents a variation of said output signal.

3. The method of claim 1, including the steps of:

characterizing said occupant as a cinched child seat when said integration value is above said threshold; and

characterizing said occupant as a normally seated adult when said integration value is below said threshold.

4. The method of claim 1, wherein said sensor is a pressure sensor coupled to a fluid filled seat bladder, and said specified frequency range is defined by a lower frequency of about 10 Hz and an upper frequency of about 50 Hz.

5. The method of claim 1, wherein said sensor is an accelerometer affixed to a central frame element of said seat.

6. The method of claim 5, wherein said specified frequency range is defined by a lower frequency of about 50 Hz and an upper frequency of about 100 Hz.

7. The method of claim 1, wherein said threshold is calibrated to compensate for variability of said integration value due to effects of vehicle motion at different speeds of said vehicle.