Communications: electrical – Land vehicle alarms or indicators – Of collision or contact with external object
Reexamination Certificate
2002-09-12
2004-06-29
Wu, Daniel J (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Of collision or contact with external object
C180S282000, C701S045000
Reexamination Certificate
active
06756889
ABSTRACT:
TECHNICAL FIELD
This invention pertains to computer based methods for determining whether certain frontal or angular crash situations in a vehicle require activation of a safety device. More specifically, this invention pertains to the use of two acceleration sensors, one in the passenger compartment and one centrally located at the front of the vehicle in such a method. The method involves the continuous selective use of velocity and displacement values from the two sensors in at least three different modes of crash situations to determine whether a safety device, such as a passenger compartment air bag, is to be activated and, if so, how it is to be activated.
BACKGROUND OF THE INVENTION
Safety devices for the protection of the operator and passengers of automotive vehicles have been in use for many years. Many safety features function in a crash situation without external activation. Seat reinforcement, seat headrests, and passenger compartment padding are examples of such safety items. Other safety devices such as supplemental inflatable restraints, popularly known as air bags, require external activation when a crash event is apparently occurring.
Air bags comprise an inflatable bag, an electrically actuated igniter and a gas generator. Each bag is folded and stored with its igniter and gas generator in the steering wheel pad, instrument panel, door panel or body pillar. Air bags also require a collision detection system that determines when the bags should be deployed and signals the ignition of one or more charges (or stages) of the gas generator. Current air bag, and other passive passenger protection systems, rely on acceleration sensors (detecting abrupt vehicle deceleration) and a micro-processor based controller. An acceleration sensor is a device that continually senses accelerative forces and converts them to electrical signals. The controller continually receives acceleration signals from each sensor and processes them to determine whether a crash, situation is occurring that requires air bag deployment.
The content of such a crash detection system for safety device actuation usually depends upon the method or algorithm used by the controller for assessing crash severity. Most systems rely on an acceleration sensor placed in the passenger compartment, close to the center of gravity of the vehicle. This sensor is often put under the passenger seat as part of a sensing and diagnostic module (SDM) of the vehicle crash sensing system. In addition, some systems place one or more accelerometers at the center or sides of the radiator cross-tie-bar to detect vehicle front-end deceleration indicative of a crash. These front-end accelerometers have been called electrical frontal sensors, EFS. The crash detection controller receives signals from the acceleration sensor(s) and evaluates them in a preprogrammed manner to determine whether air bag deployment is necessary. The program may also determine the degree of deployment, e.g., one or two inflation stages, of the bag.
The algorithms of crash sensing controllers have involved increasing degrees of complexity. Acceleration values from a single sensor (e.g., the SDM sensor) have simply been compared with a pre-determined threshold acceleration value as a test for device deployment. Values from more than one sensor location have been used in the crash sensing practices. Acceleration values have been integrated over time to yield crush velocities, and further integrated to yield crush displacement values. Further, the derivative of acceleration values have been determined as “jerk” values Such velocity and displacement values, and jerk values, have also been compared with respective pre-determined threshold values as a more selective basis for achieving timely air bag. Also, acceleration data has been used in combination with seat occupancy information and seat belt usage.
There are variants in vehicle front-end crash modes and, of course, there can be considerable variation in the severity of a crash depending upon the structure and mass of a vehicle and its velocity at the onset of a crash. With respect to front-end crash modes, a vehicle may crash head-on with another vehicle (a full frontal crash mode) or with a narrower fixed object such as a pole. Front-end crashes of a vehicle with other vehicles often occur in an angular mode between head-on (zero degree) and a side-ways crash (ninety degrees). A further distinction is often made between an angular crash with a rigid or non-yielding object and an offset deformable barrier (OBD mode).
Actual vehicular crash testing reveals different patterns of front end and passenger compartment crush velocities and displacements associated with different crash modes. In fact, considerable crash testing of a vehicle has been required to provide the substantial database of threshold values of jerk, acceleration, velocity and/or displacement over a crash period for use by a crash-sensing controller. Such data must be compiled from suitably instrumented test vehicles over the relevant duration of each test crash period. Depending upon the nature and severity of a crash, an airbag deployment decision may be made by the controller process at any time during a period of from about 15 milliseconds (ms) to 70 ms or 100 ms or so from the onset of the crash.
It would be desirable to obtain a discriminative and robust crash sensing algorithm that could utilize suitable crash simulation models as a basis for establishing threshold values of, e.g., velocity and displacement at two or more acceleration sensor locations in a vehicle. Crash simulation models may be based, for example, on a suitable Finite Element Analysis (FEA). As stated, such threshold values must be obtained over a period of up to about 70 to 100 ms from the recognition of a crash event and stored in the memory of the controller. Accordingly, it is an object of this invention to provide a method of activating an air bag or other crash-responsive safety device that can utilize velocity and displacement values obtained from a suitable crash model. It is a further object of this invention to provide such a method that utilizes velocity and displacement values from two sensors, one located in the passenger compartment and one located centrally at the front of the vehicle. It is a still further object of this invention to provide an airbag activation method that utilizes a consideration of three or more distinct vehicle crash modes in use of time integrated acceleration sensor data.
SUMMARY OF THE INVENTION
This invention provides a vehicle crash sensing system which better discriminates severe crash events that require actuation of safety devices from minor crash incidents that do not require such actuation. This is accomplished by use of two acceleration sensors and an associated signal processing algorithm in a microprocessor. The crash sensing algorithm is composed of at least three parallel assessment branches or modules for detecting different crash modes, each of which uses only current velocity and displacement measures calculated by integrating the acceleration data recorded from the two vehicle mounted accelerometers.
In accordance with the invention a centrally located, front end acceleration sensor is employed together with a sensor in the passenger compartment. For example, the front end acceleration sensor, EFS, may be mounted at the center of the radiator cross-tie-bar in the engine compartment of the vehicle for sensing the acceleration of the tie-bar. The vehicle is also provided with an accelerometer in the passenger compartment, such as a location underneath the passenger seat as a part of a sensing and diagnostic module (SDM) of the vehicle crash sensing system. The vehicle crash sensing system detects and discriminates severe crash events from minor crash incidents by signals derived from the front end acceleration sensor and the SDM acceleration sensor. Such derived signals are used in the signal processing algorithm of this invention which is implemented in the control program within the microcomputer of the cr
Lin Chin-Hsu
Neal Mark O.
Sala Dorel M.
Wang Jenne-Tai
General Motors Corporation
Huang Sihong
Marra Kathryn A.
Wu Daniel J
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