Vehicle seat occupant weight estimation method with floor weight compensation

• US 6,587,770 B1
• Filed: 02/26/2002
• Issued: 07/01/2003
• Est. Priority Date: 02/26/2002
• Status: Expired due to Fees

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Murphy, Morgan D., Fortune, Duane D., Gray, Charles A., Patterson, James F., Sullivan, Stuart S., Kaltenbacher, Phillip E II
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US10/082,460
• Time in Patent Office: 490 Days
• Field of Search: 701/45, 701/46, 701/47, 701/36, 280/728.1, 280/735, 280/734, 307/10.6, 180/268
• US Class Current: 701/45
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60R 2021/0004 Frontal collision
• CPC Class Codes: B60R 2021/0006 Lateral collision
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/01546 using belt buckle sensors
• CPC Class Codes: B60R 21/0155 sensing belt tension
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015

Abstract

An improved vehicle seat occupant weight estimation method detects weight applied to both the seat cushion and the floor forward of the seat, and increases the measured seat weight of the occupant to account for occupant weight off-loaded to the floor. Fluid-filled bladders or other sensors are arranged to detect occupant seat weight and the weight applied to the vehicle floor forward of the seat. Upon opening of a vehicle door or an off-to-on transition of the vehicle ignition switch, the seat and floor weight sensors are monitored to detect the presence of an occupant. When the seat becomes occupied, or whenever there is a large change in the measured seat weight, the seat and floor weight are recorded, the occupant weight is estimated according to the recorded seat weight, and the inflatable restraints are allowed or suppressed based on the estimated occupant weight. When a sustained occupant weight shift is detected, the estimated occupant weight is increased in proportion to the amount of weight shifting, but is limited to a maximum value based on the detected floor and seat weights.

Claims

1. A method of operation for an occupant detection system that allows or suppresses deployment of an inflatable restraint in a vehicle based on an estimate of occupant weight, the method comprising the steps of:

measuring a seat weight based on weight applied to a seat of the vehicle;

measuring a floor weight based on weight applied to a floor of the

vehicle forward of the seat;

setting the estimate of occupant weight according to the measured seat weight;

monitoring the measured seat weight and measured floor weight during operation of the vehicle; and

increasing the estimate of occupant weight to compensate at least in part for occupant weight off-loaded to the floor when the monitored weights indicate shifting of occupant weight.

2. The method of claim 1, wherein the seat weight is measured by sensing a fluid pressure in a seat bladder disposed in a bottom cushion of said seat, and the floor weight is measured by sensing a pressure in a floor bladder disposed on said floor forward of the seat.

3. The method of claim 1, wherein the step of setting the estimate of occupant weight includes the steps of:

initializing the estimate of occupant weight according to the measured seat weight;

detecting a change in the measured seat weight; and

re-initializing the estimate of occupant weight according to the measured seat weight each time the detected change in measured seat weight exceeds a first threshold indicative of a relatively large weight change.

4. The method of claim 3, including the step of:

enabling detection of occupant weight shifting when the detected change in measured seat weight is between the first threshold and a second threshold that is lower than the first threshold.

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

detecting instantaneous occupant weight shifting when the measured seat weight changes from the estimate of occupant weight by a specified amount, and the measured seat and floor weights change in opposite directions; and

indicating shifting of occupant weight between the seat and floor when instantaneous occupant weight shifting is detected for a least a predetermined time interval.

6. The method of claim 1, wherein the step of increasing the estimate of occupant seat weight includes the steps of:

detecting changes in the measured seat and floor weights; and

increasing the estimate of occupant seat weight according to the change in the measured seat weight or the change in the measured floor weight, whichever is less.

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

limiting said increasing of the estimate of occupant weight Such that the estimate of occupant weight does not exceed a sum of the measured seat and floor weights.

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

limiting said increasing of the estimate of occupant weight such that the estimate of occupant weight does not exceed the measured seat weight by a specified percentage.

9. The method of claim 8, wherein the specified percentage is varied as a function of the measured seat weight.

10. The method of claim 8, wherein the seat has a height with respect to the floor that is adjustable, and the specified percentage is varied as a function of the measured seat weight and the seat height.