Data processing: vehicles – navigation – and relative location – Relative location – Collision avoidance
Reexamination Certificate
1998-12-11
2001-01-09
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Relative location
Collision avoidance
C701S047000, C701S300000, C340S436000, C340S901000, C340S903000
Reexamination Certificate
active
06173233
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to proximity sensors and more particularly relates to sonic proximity sensors adapted to sense targets, such as people and animals, which are located behind a vehicle.
2. Description of the Prior Art
The problem of detecting warm bodies, such as people and animals, in an area behind a vehicle is well established. The problem is especially acute in the field of farm tractors and lawn mowing equipment. Presently, more than five thousand injuries occur each year as a result of misuse of such equipment. A large percentage of these injuries are inflicted when a tractor is backing up and inadvertently strikes an unseen victim, resulting in impact injuries and lacerations from contact with a spinning lawn mower blade.
Various forms of electronic sensors have been employed in collision avoidance systems to detect targets in the path of a moving vehicle. These sensor types include radio-based sensors (radar), ultrasonic sensors, laser-based sensors and passive infrared sensors. Each of these sensor types has associated advantages and disadvantages. For example, radar-based systems have the ability to detect the position and relative speed of a target in the vicinity of a vehicle. However, such sensors are costly and are most responsive to hard, reflective surfaces such as other vehicles, buildings and the like. Infrared sensors, such as passive infrared sensors which are well known in the art, employ pyroelectric or thermopile detectors to sense the movement of a warm body in the sensor's field of view. Such sensors are commonly used in security systems to detect the presence of an intruder within a protected premise and have also been used in robotic systems to detect and track people in the vicinity of a mobil robotic system. While passive infrared sensors can discriminate between a warm body, such as a person, and inanimate objects, these sensors cannot determine the range of a target from a vehicle. Passive infrared sensors are also subject to false detection of a warm body due to thermal variation within the sensor's field of view.
It is well established that sonic sensors can be employed to detect the presence of a target in the proximity of a vehicle. Such technology, commonly referred to as sonar, transmits a burst of sonic energy which will reflect off a target proximate to a vehicle. After transmitting the burst of sonic energy, the sonar system enables a receiver to detect any reflected sonic energy. As the distance of a target is proportional to the time that it takes for the sonic energy to reach a target and return to the receiver, such sonar systems are capable of not only determining the presence of a target, but also can accurately render the distance of the target with respect to the vehicle.
The use of sonic sensors to detect obstacles in a region behind a moving vehicle is also known in the art. For example, the article “Limitations of Ultrasonic Obstacle Sensors for Industrial Lift Truck Applications,” by Walter J. Girardi, published by SAE International, SAE Technical Paper Series No. 961809, discloses the use of an ultrasonic sensor on a lift truck to reduce accidents involving pedestrians and moving industrial lift vehicles. The system disclosed employs a single ultrasonic sensor mounted on a center portion of the rear of a lift truck. This system provides a conical protection area behind the vehicle and does not provide 180° coverage behind the lift truck. Accordingly, the system disclosed does not provide any coverage in the region directly to the left or the right of the rear of the vehicle, which are within the vehicles immediate turning radius. Therefore, while it is known to use ultrasonic sensors to detect the targets behind the vehicle, there are shortcomings with those devices known in the prior art and there remains a need for a back-up proximity sensor system for a vehicle which overcomes these problems.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a back-up proximity sensor which can detect targets in at least one region behind a vehicle.
It is another object of the present invention to provide a back-up proximity sensor for a vehicle which provides redundant sensor coverage in a region directly behind the vehicle.
It is yet another object of the present invention to provide a back-up proximity sensor for a vehicle which can determine the distance of a detected target behind the vehicle.
It is a further object of the present invention to provide a back-up proximity sensor for a vehicle which can determine the approximate direction of a detected target behind the vehicle.
It is still a further object of the present invention to provide a back-up proximity sensor for a vehicle which is substantially immune from both radio interference and thermal interference.
It is yet a further object of the present invention to provide a back-up proximity sensor that can reliably detect a target located within a 10 ft. radius about the rear portion of a vehicle.
It is still a further object of the present invention to provide a back-up proximity sensor which can detect a target and alter the operation of a vehicle within one second.
It is yet another object of the present invention to provide a back-up proximity sensor for a vehicle which provides coverage in a 180° region behind the vehicle.
It is still a further object of the present invention to provide a back-up proximity sensor that can reliably detect a target in a region behind a vehicle with up to one foot of vertical terrain variation.
It is another object of the present invention to provide a back-up proximity sensor employing sonic transducers which include a self test feature.
It is yet a further object of the present invention to provide a back-up proximity sensor employing sonic transducers having dynamic gain control to compensate for decreased return signal strength with increasing target distance.
In accordance with one form of the present invention, a back-up proximity sensor for a vehicle is formed with a first sonic transducer and a second sonic transducer mounted on a rear portion of a vehicle. The first sonic transducer and second sonic transducer each transmit and receive sonic energy in a substantially horizontal first sector and second sector respectively. The first sonic transducer is horizontally separated from the second sonic transducer and the first and second sonic transducers are angularly directed toward each other such that the first sector and second sector at least partially overlap.
The first and second sectors each preferably cover a region of about 90° with a radius of about 10 feet. The first and second sonic transducers are each angularly directed toward each other at approximately 45° such that the first sector overlaps the second sector in a region directly behind the vehicle. This provides three zones of coverage. The first zone of coverage features redundant protection in the region directly behind the vehicle where the first sector and second sector overlap. The non-overlapping regions of the first and second sectors extend laterally beyond the edges of the vehicle and define the second and third protected zones respectively. The second and third zones provide protection in the periphery of the vehicle such that the areas immediately to the left and right of the vehicle are protected, providing enhanced safety in the area of the turning radius of the vehicle.
In accordance with a method of detecting a target behind a vehicle, two sonic transducers are operated in a manner to provide three protection zones. During a first time period, the first sonic transducer transmits a pulse of sonic energy. During a second time period, the first and second sonic transducers are sampled to determine whether a target is within the first sector. During a third time period, the second sonic transducer transmits a pulse of sonic energy. During a fourth time period, the first and second transducers are sampled to determine whether a target is
Bernhard Richard G.
Janutka William J.
Pahl Birger
Cuchlinski Jr. William A.
Donnelly Arthur D.
Eaton Corporation
Hoffmann & Baron , LLP
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