Fuzzy logic control method for deployment of inflatable restraints

• US 20020077736A1
• Filed: 12/15/2000
• Published: 06/20/2002
• Est. Priority Date: 12/15/2000
• Status: Active Grant

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Tian, Ming, Neal, Mark O., Wang, Jenne-Tai
• Granted Patent: US 6,662,092 B2
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60R 21/013 including means for detecting collisions, impending collisions or roll-over

Abstract

An improved control for the deployment of individual stages of a vehicle inflatable restraint during a crash event utilizes a fuzzy logic control to determine the crash severity, and a deployment control algorithm to control deployment of the restraints based on the determined crash severity and the elapsed time. In a preferred implementation, the crash severity is not determined until the measured acceleration and the corresponding change in velocity exceed respective thresholds, and a prediction of occupant movement due to the measured acceleration exceeds a threshold. Once the respective thresholds are exceeded, the fuzzy logic control is initiated to determine the crash severity, and the deployment control algorithm determines whether to deploy individual stages of the restraint based on comparisons of the determined crash severity and the elapsed time with respective thresholds.

Claims

1. A control method for controlling deployment of individual stages of a vehicle inflatable restraint based on at least one measure of vehicle acceleration during a crash event and an elapsed time of the crash event, the method comprising the steps of:

computing a change in velocity corresponding to the measured acceleration;

determining a severity of the crash event by applying fuzzy logic membership functions and predetermined fuzzy logic rules to the elapsed time and the computed change in velocity; and

controlling deployment of the individual stages of the restraint based on comparisons of the elapsed time and the determined crash severity to respective predetermined thresholds.

2. The control method of claim 1, wherein the step of determining the severity of the crash event includes the steps of:

applying the elapsed time and the computed change in velocity to respective predetermined membership functions;

evaluating truth values for different levels of crash severity using predetermined membership function rules; and

consolidating said truth values to determine the severity of the crash event.

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

obtaining first and second measures of vehicle acceleration during the crash event;

computing first and second changes in velocity corresponding to the respective first and second measures of vehicle acceleration; and

determining the severity of the crash event by applying fuzzy logic membership functions and predetermined fuzzy logic rules to the elapsed time and the first and second computed changes in velocity.

4. The control method of claim 1, including the steps of:

calculating a prediction of occupant movement due to the measured acceleration; and

delaying the step of determining the severity of the crash event until the prediction of occupant movement exceeds a predetermined threshold.

5. The control method of claim 1, wherein the step of controlling deployment of the individual stages of the restraint includes the step of:

comparing the determined crash severity to different crash severity thresholds associated with different individual stages of the restraint.

6. The control method of claim 1, wherein the step of controlling deployment of the individual stages of the restraint includes the steps of:

comparing the determined crash severity with a first crash severity threshold associated with a first stage of the restraint;

repeating the step of determining the severity of the crash event if the comparison reveals that the determined crash severity is less than the first crash severity threshold and the elapsed time is less than a reference time; and

initiating deployment of the first stage of the restraint if the comparison reveals that the determined crash severity exceeds the first crash severity threshold.

7. The control method of claim 6, including the step of:

resetting the elapsed time of the crash event if the elapsed time is greater than said reference time.

8. The control method of claim 1, including the steps of:

initiating deployment of a first stage of the restraint if the determined crash severity exceeds a first crash severity threshold associated with a first stage of the restraint;

after initiating deployment of the first stage of the restraint, comparing the determined crash severity with a second crash severity threshold that is larger than the first crash severity threshold;

repeating the step of determining the severity of the crash event if the comparison reveals that the determined crash severity is less than the second crash severity threshold and the elapsed time since initiating deployment of the first stage of the restraint is less than a reference time; and

initiating deployment of a second stage of the restraint if the comparison reveals that the determined crash severity exceeds the second crash severity threshold.

9. The control method of claim 8, including the step of:

discontinuing the control method if the elapsed time is greater than said reference time.