Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1999-04-23
2001-04-03
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C180S274000
Reexamination Certificate
active
06212456
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an impact sensor system for use in triggering operation of a deployable device for protecting a pedestrian hit by the front of a vehicle. The invention also relates to an impact sensing method and to a pedestrian protection system which employs the impact sensor system.
BACKGROUND OF THE INVENTION
When a pedestrian is hit by a motor vehicle, for example a car, one type of injury can be caused by a subsequent collision between the pedestrian's head and the hood of the vehicle. Many impact protection systems have been devised to reduce the effects of such collisions, for example hood-mounted airbags or energy-absorbing hood panels. Such deployable systems will be referred to as cushioning devices.
Cushioning devices require a sensor to be used to detect pedestrian impacts, and it is highly desirable for that sensor to discriminate between impact with a pedestrian and other types of impact. The decision of whether to deploy or not to deploy must be made in a very short space of time after detecting an initial impact at the front of the vehicle.
One pedestrian impact sensor system which has been proposed is described in International Patent Application No. WO 97/18108. This system uses a first sensor on the front bumper (fender) and a second sensor on the front edge of the hood of the vehicle. By measuring the time difference between triggering of the first sensor and triggering of the second sensor, and the magnitudes of the signals from those sensors, the system can distinguish between impacts with pedestrians and other sorts of impacts.
It is necessary for there to be an impact between the pedestrian and the vehicle hood before any deployment of a safety device can be triggered.
SUMMARY OF THE INVENTION
According to an aspect of the present invention there is provided a pedestrian impact sensing system for a motor vehicle comprising: a front end assembly mounted on a front end of the vehicle; a cushioning device mounted to the vehicle; memory means for storing pressure pattern data characteristic of pedestrian collisions; sensing means for measuring the loads acting simultaneously on different regions across the front end assembly to produce a pressure pattern; means for monitoring changes in measured pressure patterns over time; means for comparing the changing pressure patterns with stored pressure pattern data; and means for sending a triggering signal for activating the cushioning device when a correspondence is identified between the monitored changing pressure pattern and stored pressure pattern data.
By measuring a changing pressure pattern across the front of the vehicle, it is not necessary to detect collision with the hood of the vehicle.
Preferably the sensing means are located in the front bumper of the vehicle. This permits the use of a single pressure sensitive matrix associated with the bumper. For convenience hereinafter the invention will be described with reference to a pressure sensitive matrix in a front bumper. However, it is to be understood that the invention is not limited to this embodiment.
The pressure pattern, rather than the magnitude of loading of individual matrix cells, principally characterises a pedestrian impact, while the change of pressure pattern with time provides discrimination data relating to magnitude. An advantage of this system is that variation in material properties of the bumper system, for example due to environmental effects or manufacturing variation, may affect the magnitude of load measured by individual cells, but will not significantly affect the pressure pattern.
The comparison means preferably comprises a neural network, which is particularly able to be adaptable to complex cases. However, a conventional algorithm could also be used.
Suitable known matrix technologies may be used for the pressure sensitive matrix, for example force-sensitive resistors, capacitive arrays, strain gauges and piezo-resistive or capacitive load cells.
The pressure sensitive matrix may be sandwiched between a rigid bumper beam and the bumper cover or trim panel. An energy absorbing module, for example a foam module, is preferably held under compression against the matrix. The matrix may be sandwiched between the foam module and the bumper beam, between the foam module and the bumper cover, or within the foam module.
In a particularly preferred embodiment, the bumper is provided with a plurality of discrete loading features, each corresponding to a region of the bumper where an element of the pressure pattern is to be measured. Each loading feature may comprise a projection in the bumper cover, in the foam module, or in the pressure sensitive matrix. The loading features improve load transmission to the sensor elements of the matrix.
Any vehicle systems that use a radiated field (for example radar, infrared, ultrasound, or microwave) to establish conditions outside the vehicle exterior could be used as a low-level trigger to activate a high processing rate in the impact sensor system. For example, if an automatic cruise control system sensed relative movement between the vehicle and an external object, the pedestrian impact sensor could commit system resources to discriminating an impact, given the higher level of event confidence gained. This information could also be used in the deployment decision-making process, similar to an interior airbag controller's “safing” sensor.
A further aspect of the present invention provides a method for detecting pedestrian impact with a motor vehicle, comprising: measuring loads acting simultaneously across the front of the vehicle to produce a pressure pattern; monitoring changes in measured pressure patterns over time; comparing the changing pressure patterns with stored data for changing pressure patterns characteristic of pedestrian collisions to determine if there is a correspondence; and sending a triggering signal to activate a cushioning device if a correspondence is identified.
According to another aspect of the present invention there is provided a pedestrian protection system for a motor vehicle, comprising: a cushioning device for cushioning an impact with a pedestrian, being actuatable by a triggering signal; sensing means for measuring the loads acting simultaneously on different regions across the front of the vehicle to produce a pressure pattern; means for monitoring changes in measured pressure patterns over time; means for comparing the changing pressure patterns with stored data for changing pressure patterns characteristic of pedestrian collisions; and means for sending a triggering signal to the cushioning device when a correspondence is identified between a measured changing pressure pattern and stored data.
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patent: 7-108903 (1995-04-01), None
patent: 97/18108 (1997-05-01), None
Jaguar Cars Limited
Zanelli Michael J.
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