Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Patent
1999-05-07
2000-12-05
Cuchlinski, Jr., William A.
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
701 36, 701124, 2807283, 2807302, 280734, 280735, 340436, 307 91, G06F 700
Patent
active
061578800
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
THE PRESENT INVENTION relates to a crash detector and more particularly, relates to a crash detector for use in a motor vehicle. In particular, the present invention relates to a crash detector adapted to respond to a side impact.
BACKGROUND OF THE INVENTION
It has been proposed to provide a crash detector to respond to a side impact in a motor vehicle. Typically, the crash detector incorporates a sensor which is mounted on the door or which is mounted on part of the door-frame, such as the B-pillar. The sensor may comprise an accelerometer.
When a vehicle provided with such crash detector is involved in a side impact, part of the vehicle, where the accelerometer is mounted, is deformed, and the accelerometer is exposed to a high acceleration. The crash detector incorporates means responsive to this sensed high acceleration to deploy a safety device, such as an air-bag or a seat-belt pre-tensioner.
However, it has been found that an accelerometer mounted on the door of a motor vehicle or mounted on part of the door-frame may be subjected to a high acceleration when the door of the vehicle is slammed. The high acceleration may be sufficient to cause the safety device be deployed. This is clearly disadvantageous, since it is most undesirable for the safety device to be deployed as a consequence of a door slam.
It is not, however, appropriate simply to adjust the sensitivity of the accelerometer, since in a side impact situation it is very important that the safety device is deployed, and is deployed swiftly.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved crash detector.
According to this invention there is provided a crash detector for activating a safety device in a vehicle in response to a side impact comprising an accelerometer mounted on the door or part of the monocoque shell of the vehicle adjacent the door, the accelerometer being adapted to provide an acceleration signal indicative of the magnitude of the lateral acceleration to which the accelerometer is exposed, the signal increasing with increasing inward acceleration, and the direction of sensed acceleration relative to the centre-line of the vehicle, means being provided adapted to process the acceleration signal from the accelerometer to generate a control signal, the processing means being adapted to alter the value of the control signal, at least a major component of the alteration being an increase in the value of the control signal or an adjustment of the value of the control signal to make the control signal converge to at least an average of the acceleration signal from the accelerometer during periods of time in which the acceleration signal from the accelerometer indicates an inward acceleration in excess of predetermined level of acceleration, and at least a major component of the alteration being a reduction of the value of the control signal, by a substantially predetermined amount during successive periods of time when the acceleration signal from the accelerometer is indicative of inward acceleration which is less than the predetermined level, the control signal being passed to threshold means adapted to respond to enable actuation of the safety device only when the threshold has been exceeded.
Conveniently the predetermined level corresponds to zero inward acceleration.
Advantageously when the output signal from the accelerometer is indicative of inward accelerations, the control signal is adjusted by causing the control signal to converge towards a low pass filtered signal derived from the acceleration signal from the accelerometer.
Conveniently the low pass filtered signal is generated by, during each successive period of time, taking the then-current value for sensed acceleration and multiplying it by a constant k which is greater than zero but which is less than 1, and adding the resultant value to the final value for the control signal generated during the proceeding instant of time, multiplied by the difference between 1 and the constant k.
Advantageously during each per
REFERENCES:
patent: 5779264 (1998-07-01), de Mersseman et al.
de Mersseman Bernard
Poux Frederic
Villanneau Jerome
Autoliv Developement AB
Beaulieu Yonel
Cuchlinski Jr. William A.
Kinberg Robert
Spencer George H.
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