Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Automatic route guidance vehicle
Reexamination Certificate
2000-11-09
2001-09-11
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Automatic route guidance vehicle
C180S167000, C180S168000
Reexamination Certificate
active
06289269
ABSTRACT:
TECHNICAL FIELD
This invention relates to vehicle autoguidance systems and more particularly to an apparatus and a method for use in guiding a vehicle on a roadway along an elongated guide member emitting a magnetic field.
BACKGROUND OF THE INVENTION
It is well known to employ the magnetic field of a member or members associated with a roadway to guide vehicles having an automatic steering system. It is also known to employ a guidance wire system associated with a roadway that emits a radio signal which is picked up by an antenna on a vehicle and processed by an onboard computer that controls vehicle steering.
Although autoguidance systems employing radio frequency wires are satisfactory in many respects, they do have significant disadvantages. For example, power must be supplied to the wire, not always feasible in remote areas. Furthermore, RF wire guide systems require use of a continuous wire loop in or on the roadway and each loop must be associated with its own power supply source or sources. Such arrangements are quite expensive and prone to damage; for example, a lightning strike at or near an RF wire installation can knock out the system.
Magnetic vehicle autoguidance systems also have a number of limitations. According to this approach, either spaced magnetic field emitters or elongated elements such as magnetic tape are positioned at the roadway and the magnetic field or fields emitted thereby are sensed and a resultant signal produced to control a vehicle automatic steering system.
In order to sense the magnetic field of the tape a sensor must be placed in very close proximity thereto. Not only is the magnetic field of the tape relatively weak, the sensor picks up an ambient magnetic field including that produced by the earth itself. This problem becomes even more aggravated if bridges or other metal structures are in the vicinity.
Because of road irregularities or other factors, it is often difficult or even impossible to maintain the position of a sensor on a vehicle very close to the road surface, as presently required to pick up weak magnetic signals produced by available magnetic tapes and distinguish them from ambient magnetic fields.
Wide magnetic tapes has been utilized in an attempt to strengthen the magnetic guidance field, however such an approach is not only expensive but provides only a partial solution to the problem of ambient or extraneous magnetic fields interfering with operation of the autoguidance system.
DISCLOSURE OF INVENTION
The present invention relates to a system which allows use of a magnetic tape having a very weak field (which may for example be similar in strength to the earth's field strength) to be utilized in a vehicle autoguidance system. A relatively narrow magnetic tape (in the order of two inches wide, for example) can be utilized. In addition, the sensor employed to detect the magnetic field emitted thereby can be maintained a significant distance, e.g. six inches or more, from the roadway so that roadway irregularities or objects on the roadway will not interfere with proper operation of the system.
The present invention even makes it feasible to use a magnetic tape embedded in a roadway beneath the roadway surface to provide a magnetic guide field.
The apparatus of the invention is for use in guiding a vehicle on a roadway along an elongated guide member emitting a magnetic field.
The apparatus includes a first sensor attached to the vehicle for detecting both the magnetic field emitted by the elongated guide member and an ambient magnetic field not emitted by the elongated guide member.
The first sensor produces a primary signal representative of the detected magnetic field emitted by the elongated guide member and the ambient magnetic field.
A second sensor is attached to the vehicle for detecting the ambient magnetic field but not a substantial portion of the magnetic field emitted by the elongated guide member.
The second sensor produces a reference signal representative of the ambient magnetic field.
A signal processor processes the primary and reference signals to subtract the reference signal from the primary signal and produce a steering signal for transmission to the automatic steering system on the vehicle.
The present invention also encompasses a method.
Other features, advantages, and objects of the present invention will become apparent with reference to the following description and accompanying drawings.
REFERENCES:
patent: 5175480 (1992-12-01), McKeefery et al.
patent: 5404087 (1995-04-01), Sherman
patent: 5938704 (1999-08-01), Torii
Barrier Systems, Inc.
Beaulieu Yonel
Cuchlinski Jr. William A.
Lampe Thomas R.
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