Communications: electrical – Land vehicle alarms or indicators – Of relative distance from an obstacle
Reexamination Certificate
2000-01-07
2001-05-01
Trieu, Van T. (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Of relative distance from an obstacle
C340S436000, C340S903000, C342S070000
Reexamination Certificate
active
06225891
ABSTRACT:
FIELD OF INVENTION
This invention relates generally to an anticipatory object detection system, and more particularly to an anticipatory object detection system for an automobile passenger restraint system which detects a Doppler shift in a received signal reflected from an object, determines the range of the object and whether a collision with the object is imminent, and if so, determines the offset of the collision from the center of the automobile.
BACKGROUND OF INVENTION
Air bags are widely used in passenger cars, light trucks and vans as auxiliary protection devices to seat belts for increased driver and occupant protection in collision situations. The air bag was designed to enhance the protection offered by seat belt systems, especially in higher speed front impact crashes where minor belt-induced injuries and serious head and chest injuries can still occur to occupants restrained only by seat belts.
In most collisions, the decision to deploy the air bag is not made until late in the crash event, after contact with an object when a shift of occupant position is likely. This leaves the occupant vulnerable to serious injury or death by the inflation or unfurling of the air bag as it deploys. This raises particular concerns when the occupants are children or the elderly who tend to be more physically susceptible to injury. One method of mitigating injuries caused by deployment of the air bag is to use a pre-crash sensor to detect an imminent collision and help reduce the decision time of air bag deployment.
Primarily for reasons of economy, crash detection technology is currently provided by the use of a single point, fully electronic sensor located in the passenger compartment. The function of the crash sensor is to measure the crash severity as it occurs by measuring changes in velocity and, if a threshold is exceeded, air bag inflation is initiated. The output of this sensor is processed in a variety of ways. It can be filtered to provide a measure of the basic crash pulse, analyzed to establish the rate of acceleration change, integrated to indicate velocity change, or analyzed for frequency content or other parametrics. These measurements are then evaluated by a fuzzy logic system to provide reliable determination of the severity of the crash in progress, thus allowing for deployment initiation as early as possible. However, this processing takes time. In low speed crashes which produce velocity changes at or near the deployment threshold, the decision to deploy the air bag is not made until very late in the crash event, typically 25-50 milliseconds after contact. In such lower speed crashes an unbelted occupant will move closer to the air bag before inflation when compared to an occupant in a higher severity crash. The close proximity to the deploying air bag increases the chance of severe injury or death to the occupant as the pellets explode to inflate the air bag, not only because of the force of the inflating air bag, but from the heat generated from the explosion as well. Thus, current crash sensing technology provides less than ideal protection to the occupant in slower speed crashes.
A wide range of sensing devices have been investigated for a pre-crash sensor, including ultrasonic, infrared, and microwave radar. Of these, microwave radar has proven to be the strongest candidate for pre-crash detection for the simple reason that microwave radar is less affected by most environmental conditions that exist in driving situations, unlike ultrasonic and infrared sensors.
Use of microwave radar for primary air bag deployment has been investigated in the past. However, these systems required the use of Fast Fourier Transforms (FFT) to extract the harmonic components, which typically cost hundreds of dollars, and complex processors to run the systems due to the complex calculations performed. Other systems that performed harmonic binning spent considerable time monitoring each harmonic amplitude to determine range. These systems also required complex processors to perform the calculations necessary to detect the range of an object. Further, given the number of calculations, these processors required considerable time to determine the range and necessarily lag behind the actual range of fast moving objects. Thus, the high cost of early systems as well as the inability of radar to determine target mass deemed the use of microwave radar unacceptable. These pre-crash sensors detected objects that were too distant to pose a threat, or objects that were not on a collision path with the automobile such as mailboxes, signs and sidewalks.
U.S. Pat. No. 5,826,216, which is commonly assigned with the present invention, and is incorporated herein in its entirety, discloses a system that effectively uses microwave technology to determine if and when a collision will occur. However, it does not determine the offset of the collision from the sensor, which can be useful in eliminating objects which are not on a collision path with the automobile and for enabling a passive restraint system of the automobile to react appropriately, depending on where on the automobile the collision will take place.
SUMMARY OF INVENTION
It is therefore an object of this invention to provide an improved anticipatory collision sensor system that provides information regarding the location of a collision.
It is a further object of this invention to provide such an anticipatory collision sensor system that allows an air bag to deploy earlier in the crash event.
It is a further object of this invention to provide such an anticipatory collision sensor system that includes a single non-scanning sensor.
It is a further object of this invention to provide such an anticipatory collision sensor system that can determine that a collision is imminent before contact with an object.
It is a further object of this invention to provide such an anticipatory collision sensor system that is not affected by atmospheric conditions.
It is a further object of this invention to provide such an anticipatory collision sensor system that is cost effective to manufacture and implement.
It is a further object of this invention to provide such an anticipatory collision sensor system that complies with FCC regulations.
It is a further object of this invention to provide such an anticipatory collision sensor system that has a broad field of view.
It is a further object of this invention to provide such an anticipatory collision sensor system that can detect the range of an object within a predetermined distance that represents the range in which the object poses a threat.
It is a further object of this invention to provide such an anticipatory collision sensor system that eliminates objects that are not on a collision course.
It is a further object of this invention to provide such an anticipatory collision sensor system that reduces the risk of false alarms.
The invention results from the realization that a truly effective passenger restraint system can be achieved by using an anticipatory object detection system including an object detection device, which determines the range of an object by detecting the intersection of the amplitudes of the harmonic components of the reflected signal from an object which implies the instantaneous range of the object, thereafter tracking its range by counting the Doppler cycles of the reflected signal, and a Doppler period measurement device which determines a difference in consecutive periods of the Doppler frequency of the reflected signal so that a decision device can determine the likelihood and position of a collision based on the range and positional information, and the passenger restraint system can be signaled, prior to impact with the object, that collision with the object is imminent and the offset of the collision from the center of the automobile.
This invention features a wide angle, static, positional anticipatory object detection system including a transducer device for transmitting a modulated carrier signal and receiving the modulated carrier signal reflected from an object. A det
Lyons Christopher T.
Taskin Ismail
Hittite Microwave Corp.
Iandiorio & Teska
Trieu Van T.
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