Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
1999-09-17
2001-04-10
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
C342S027000, C342S028000, C342S071000, C342S104000, C342S118000, C342S147000
Reexamination Certificate
active
06215438
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a radar system adapted to be installed on a machine or vehicle, particularly a motor road vehicle, and to such a vehicle fitted with a radar system.
BACKGROUND TO THE INVENTION
It has been proposed to install radar systems in motor road vehicles and on other machinery for detecting objects of various kinds. Such systems generally use co-located and closely coupled transmitters and receivers which are arranged to detect the presence or approach of objects in a particular direction or situation, for example, when a vehicle is reversing.
However, known systems have tended to be expensive and tend only to be useful in a narrowly specified set of situations.
THE INVENTION
According to the first aspect of the invention, there is provided a radar system adapted to be installed on a vehicle (preferably a motor road vehicle) and operable to detect objects in differing fields of view of the system, the system comprising transmitter means for transmitting a radar signal; receiver means for receiving the signal after the latter has been reflected from the reflecting surface of an object to be detected; gating means for sampling the reflected signal received by the receiving means during a succession of sampling periods, each of which is delayed with respect to a respective portion of the transmitted signal by a time delay corresponding to the time taken for that portion to travel to the reflecting surface when the latter is at a notional range shell, and then back to the receiving means, so that a reflected signal received during that period is indicative of the presence of a reflecting surface at the range shell; control means for controlling the field of view of the system and sensor means which is connected to the control means and is operable to detect one or more features of the operation of the vehicle, which features are characteristic of the required field of view of the system wherein the control means in use determines said required field of view and sets the field of view of the system accordingly, in dependence on the output of the sensor means.
A single antenna may comprise both the transmitter means and the receiver means, but preferably the transmitter means and receiver means comprise a plurality of antennas.
The field of view of the system corresponds to the position(s) of the range shell relative to the vehicle, and hence defines the possible positions of any object which can be detected by the system.
Thus, if the system has only one transmitter and one receiver arranged only to detect objects in one sector relative to the vehicle (for example behind the vehicle), the alteration of the field of view is achieved simply by altering the distance of the range shell from the vehicle. If, however, the system has a plurality of suitably positioned transmitters or receivers, the angular position of a current range shell relative to the vehicle will depend on which transmitter and receiver are being used, and can be correspondingly altered by using another receiver or transmitter, thus also altering the field of view of the system.
Accordingly, depending on the configuration of the transmitter and receiver means, said control of the field of view of the system is achieved by controlling either the distance (i.e. range) of each range shell or by selection of the antenna (or pairs of antennas) and associated antenna beams to be used, thereby controlling angular position of the range shell or by controlling both distance and angular position of the range shell.
Preferably, the radar system comprises a pulsed radar system, in which the transmitted signal comprises a succession of pulses, each of which constitutes a respective one of said portions of the transmitted signal.
Preferably, the control means is operable to detect fluctuations in the signal received in a succession of sampling periods, said fluctuations corresponding to an object entering or leaving a range shell. Alternatively, the control means may be operable to detect any DC offset of signal received over a succession of sampling periods with respect to a reference level to determine whether there is an object at the range shell which object is stationary relative to the range shell.
In the former case, the control means is preferably operable also to analyse the received signals to determine the principal frequency thereof, or the time delay between detections at different range shells, and hence to estimate the velocity of the object relative to the range shells.
Preferably, the transmitter and receiver means are adapted to be mounted on the vehicle in positions which are such that, in use, the system can detect a presence of objects at any position around the vehicle.
To that end, the transmitter means and receiver means are preferably mountable in the regions of the corners of the vehicle, and are conveniently adapted to be incorporated into the vehicle bumpers.
In such a case the system can detect objects in front of, to the sides of and behind the vehicle.
This can be achieved by transmitter means comprising two antennas adapted to be mounted at diagonally opposite corner regions of the vehicle, and receiver means comprising two antennas adapted to be mounted at the other corner regions of the vehicle.
Thus, the rear transmitter antenna is used to provide signals which are reflected from objects behind the vehicle and received by the receiver antenna at the other rear corner, and also provides signals which are used to detect objects to its own side of the vehicle and are received at the receiver antenna on the front corner on the same side. Similarly, the forward transmitter antenna can provide the signals which are used to detect objects in front of and to the other side of the vehicle. This feature therefore enables a relatively large area of coverage to be achieved using fewer transmitter/receiver antennas than would be the case if the system used co-located transmitter and receiver antennas.
The sensor means may include sensors responsive to the operation of the direction indicators or to steering wheel movement of the vehicle, or to the operation of the vehicle brakes.
In the latter case, the control means may be so arranged that, when the vehicle brakes are operating, the range shells are positioned relatively close to the vehicle. The sensors responsive to the operation of the direction indicators or to steering wheel movement can cause a selection of range shells to the side of the vehicle on which the indicators are operating or towards which the wheel is turned, as the case may be.
The sensor means may additional or alternatively determine the speed of the vehicle, the distance of the range gates from the vehicle increasing if the detected speed of the vehicle increases.
The sensor means may include a sensor for determining whether reverse gear has been selected on the vehicle, in response to which the control means is operable to activate the rear antennas of the vehicle.
Additionally or alternatively, the sensor means may to advantage be operable to determine the speed with which the vehicle is reversing.
In such a case, the control means is preferably operable to set the range shell, when the vehicle is reversing, at a distance which increases with increasing speed, in accordance with a predetermined relationship.
Preferably, that relationship is such that the range shell distance is directly proportional to the speed of reversing, subject to a minimum range shell distance when the vehicle is stationary or slow moving.
Additionally or alternatively, the control means progressively increases or decreases said time delay for successive periods so that the distances of successive range shells increases or decreases between said predetermined minimum distance and the maximum distance determined in accordance with said relationship, so that the range shells sweep the area between said minimum and maximum scan distances. Such a succession of range shells will be referred to as a scanning range shell.
The rate at which said time delay is increased or decrea
Clouston Eric Nicol
Kerry Nicholas John
Oswald Gordon Kenneth Andrew
Smith Graeme Peter
Cambridge Consultants Limited
Gregory Bernarr E.
Lee Mann Smith McWilliams Sweeney & Ohlson
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