Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2000-04-19
2001-08-21
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C307S010100, C280S735000, C180S268000
Reexamination Certificate
active
06278924
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to logic systems used to control motor vehicle safety system deployment in general and to systems employing multi-step logic and multiple inputs in particular.
BACKGROUND OF THE INVENTION
Recent advances in motor vehicle safety systems involve systems that deploy various safety systems differently depending on various crash-related parameters. Typical safety systems deployed include airbags, multistage airbags, side impact airbags, seat belt tensioners and the like. The growing capacity of modern safety systems allows variations in deployment responding to the severity of a crash, and the weight and position of the vehicle occupant. The growing safety system capabilities together with improvements in the engineering understanding of the crash environment, has led to tailoring the deployment decision to consider more than simply a threshold test. Particularly with multistage airbags, information about crash severity, and vehicle occupant type and position are being used to determine deployment timing and strategy.
Data from an acceleration sensor is typically verified by a mechanical crash sensor, then analyzed to determine crash severity and crash type. Empirically derived relationships between the magnitude of the accelerations measured and the rate of onset of acceleration are used together with vehicle-specific parameters to select a deployment strategy. In a severe crash the time available for analysis is very short, and the deployment decision must be made with only a limited amount of acceleration data. Although acceleration can be integrated to determine velocity, very little velocity is lost before most of the damage occurs. Thus by the time acceleration data gives an indication of crash velocity it is too late for effective deployment of safety systems.
Crash velocity is important data input because the energy of a moving system increases with the square of the velocity. Relatively small increases in crash velocity result in substantially more energy being dissipated by the crash. Ultimately, energy dissipated in a crash characterizes to a significant extent the severity of the crash. Systems to detect imminent crashes have been developed. For example U.S. Pat. No. 5,949,366 to Herrmann teaches a system using radar which can determine crash velocity and lateral offset of a crash.
What is needed is a method of combining velocity of impact with acceleration data, and with biomechanical parameters to develop a more optimal safety device deployment strategy.
SUMMARY OF THE INVENTION
The safety system deployment method of this invention includes the steps of continuously monitoring velocity with respect to objects that are approaching a motor vehicle. When a crash is determined to be taking place based on accelerometer data a velocity of impact value is determined. This value is initially used to determine minimum conditions under which a safety system fire decision will be made. In other words, the velocity of the crash is used to set a minimum velocity, e.g. 22.5 kilometer per hour (14 miles per hour), below which safety system deployment will not be enabled.
A deployment logic system uses accelerometer data to determine the type of crash, e.g., frontal, pole impact, or angular impact, and the severity of the crash. The deployment logic system determines a point in time for safety system deployment initiation based on crash type and severity. When a deployment/fire decision is made, this determines the time-to-fire from detection of the crash onset. The accelerometer based deployment logic system is referred to as a single-point algorithm; and the single-point algorithm uses acceleration data to make the fire decision.
The second system receives the fire decision and transmits the decision to a biomechanical algorithm together with the normalized frontal velocity. Normalized frontal velocity is a good indicator of crash severity. The biomechanical algorithm utilizes the normalized frontal velocity to determine deployment sequence and strategy. The second system employs a second algorithm that takes as inputs the time-to-fire and crash type from the single-point algorithm, together with the velocity-of-crash value from the radar, and performs two operations on the inputs. The first operation is to compare an empirically derived correlation between time-to-fire and crash velocity, with the time-to-fire produced by the single-point algorithm based on accelerometer data. If the single-point time-to-fire is less than the empirically derived time-to-fire, then the radar velocity is a good indication of crash severity. If the single-point time-to-fire is greater than the empirically derived time-to-fire, then the radar indicated crash velocity overstates the severity of the crash, and a velocity between the single-point and the empirically derived time-to-fire is selected in accordance with a function.
The empirically derived correlation between velocity and time-to-fire is derived for each crash type and thus the single-point time-to-fire is compared to a different empirical correlation for each crash type.
The second operation that the second system performs is to normalize the velocity value for non-frontal crash situations to a frontal crash equivalent velocity. This normalized frontal velocity is transmitted to the biomechanical algorithm which considers vehicle occupant status sensor input data, and employs an algorithm, typically a lookup table, to choose the appropriate safety system to deploy or not as the algorithm determines, based on normalized frontal crash velocity and vehicle occupant specific parameters.
It is a feature of the present invention to provide a method of deploying motor vehicle safety systems that considers velocity of impact.
It is a further feature of the present convention to provide a method of adjusting measured velocity in view of time-to-fire times derived from crash accelerations.
It is another feature of the present invention to provide a method of normalizing crash velocity for non-frontal crashes to a frontal crash equivalent velocity.
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RL Phen et al: “Advanced Air Bag Technology Assessment—Final Report” NHTSA Apr. 1998, XP002137509.
Kosiak WK et al: “Future Trends in Restraint Systems Electronics” Automotive Engineering International, SAE International, US, vol. 107, No. 9, Sep. 1999, ISSN: 0098-2571 (The whole document).
Gioutsos Tony
Tabar Daniel N.
Breed Automotive Technology Inc.
Chin Gary
Drayer Lonnie
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