Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2002-11-25
2004-06-08
Nguyen, Tan Q. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S045000, C280S734000
Reexamination Certificate
active
06748307
ABSTRACT:
TECHNICAL FIELD
This invention pertains to computer based methods for determining whether a frontal or angular collision situation in a vehicle may require activation of a safety device. More specifically, this invention pertains to the placement of acceleration sensors in a vehicle and the continuous selective use of their integrated velocity and displacement signals in frontal and angular collision situations to help 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 collision 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 collision 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 vehicle locations, such as, 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. Some 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 collision situation is occurring that requires air bag deployment.
The content of such a collision detection system for safety device actuation usually depends upon the method or algorithm used by the controller for assessing collision 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 collision sensing system. In addition, some systems place one or more accelerometers at the center or sides of the radiator cross-tie-bar (called electrical frontal sensors, EFS) to detect vehicle front-end deceleration indicative of a collision. The collision detection controller receives signals from the acceleration sensor(s) and evaluates them in a pre-programmed 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 collision sensing controllers have involved differing degrees of complexity. For example, acceleration values from a single sensor (e.g., the SDM sensor) have 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 collision 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 deployment. Also, acceleration data has been used in combination with seat occupancy information and seat belt usage to determine air bag deployment.
There are variants in vehicle front-end collision modes and, of course, there can be considerable variation in the severity of a collision depending upon the relative structure and mass of the vehicle and its collision object as well as the relative velocities at the onset of a collision. With respect to front-end collision modes, a vehicle may collision head-on with another vehicle or fixed object in a frontal collision mode. Front-end collisions of a vehicle with other vehicles often occur in an angular mode between head-on (zero degree) and a side-ways collision (ninety degrees). A further distinction is often made between an angular collision with a rigid or non-yielding object and an offset deformable barrier (ODB mode). Exemplary vehicular collision testing reveals different patterns of front end and passenger compartment crush velocities and displacements associated with different collision modes. In fact, considerable collision testing of a vehicle has been required to provide the substantial database of threshold values of jerk, acceleration, velocity and/or displacement over a collision period for use by a collision sensing controller. Such data must be compiled from suitably instrumented test vehicles over the relevant duration of each test collision period. Depending upon the nature and severity of a collision, 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 so from the onset of the collision.
It would be desirable to further calibrate the control systems for airbags and other such devices. It is common practice in calibrating such control systems to develop the required calibration data from measurements taken in exemplary collision testing of each new vehicle model so that the control system calibration for that model is established according to its collision characteristics. It would be desirable to provide a calibration method which does not require actual testing of vehicles or reduces the need for testing of vehicles. In the prior art, attempts have been made to discriminate the severity of the collision event using acceleration and jerk signals which are difficult to generate from computer simulations, such as finite element analysis. It would be desirable to obtain a collision sensing system algorithm that relies upon velocity based measures which can be obtained without collision testing prototype vehicles to calibrate the collision sensing system. Preferably, the velocity based measures are obtained by use of computer or finite element models for calibration of collision sensing systems.
Accordingly, it is an object of this invention to provide an alternative method of activating an air bag or other collision-responsive safety device that can utilize only velocity and displacement values obtained from a suitable collision model. It is a further object of this invention to provide an airbag activation method that utilizes a consideration of more than one vehicle collision mode in use of time integrated acceleration sensor data.
SUMMARY OF THE INVENTION
This invention provides a vehicle collision sensing system which helps to determine when to actuate a safety device. This is accomplished by use of vehicle mounted accelerometers and an associated signal processing algorithm in a microprocessor. The collision sensing algorithm is composed of parallel assessment-branches or modules for detecting different collision modes, each of which uses only current velocity and displacement measures calculated by integrating the acceleration data recorded from vehicle mounted accelerometers.
In accordance with the invention at least two front end acceleration sensors are employed together with at least one sensor in the passenger compartment. For example, two frontal acceleration sensors (EFS), may be mounted at the left and right sides 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 collision sensing system. The vehicle collision sensing system detect
Lin Chin-Hsu
Neal Mark O.
Sala Dorel M.
Wang Jenne-Tai
General Motors Corporation
Marra Kathryn A.
Nguyen Tan Q.
Tran Dalena
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