Optics: measuring and testing – Range or remote distance finding – Triangulation ranging to a point with two or more projected...
Patent
1995-11-17
1998-02-03
Hellner, Mark
Optics: measuring and testing
Range or remote distance finding
Triangulation ranging to a point with two or more projected...
3561413, 342450, G01C 300, G01S 302
Patent
active
057150427
DESCRIPTION:
BRIEF SUMMARY
This invention concerns methods and apparatuses for determining the position of a mobile vehicle and for the vehicle remote control, in particular a method suitable to be applied in open spaces free from obstacles and capable of a very high precision over distances up to thousands of meters.
BACKGROUND OF THE INVENTION
It is known that plenty of methods and relevant apparatuses have been devised for determining the precise position of a mobile vehicle so that it can be remotely controlled in order to avoid the use of human drivers for cost and/or safety reasons. The common basic feature of most of these methods is the use of one or more transmitters of directive electromagnetic waves which are detected by one or more receivers. The emission angle can be contained as an information in the transmission itself or it can be obtained from the time/angular velocity relationship of the rotating transmitter. The angular data thus acquired are then electronically processed to obtain the vehicle position through quick plane trigonometry calculations, i.e. a triangulation.
The drawback of the known methods stems from the insufficient precision in determining the exact angle of emission of the electromagnetic waves, which in turn leads to an insufficient precision in obtaining the vehicle position. In fact, the precision achieved is not sufficient for a safe and precise remote control of vehicles over distances ranging from tens to thousands of meters. In particular, the highest precision is obtained by transmitting two or more directional beams to a receiver positioned on the vehicle, each beam containing the continuously changing information of its direction of emission.
Obviously, the precision of the position calculated from these angular data is directly proportional to the "resolution" thereof, i.e. to the frequency with which the information on the direction of emission is upgraded. For example, if the angular resolution (.epsilon.) is as rough as 1.degree. the resulting calculated position can not be acceptably precise. On the other hand, employing a very fine resolution (e.g. .epsilon.=0.001.degree.) requires so many data to be transmitted that the resulting transmission would imply such a high frequency as to require very sophisticated, delicate and expensive transmitters. Moreover, this type of signal is more easily subject to interference problems.
Therefore, the object of the present invention is to provide a method and apparatus capable of overcoming the above-mentioned drawbacks.
SUMMARY OF THE INVENTION
This object is achieved by means of a method method for determining the position of a mobile vehicle provided with a receiver through a triangulation performed by the receiver. The determination is based on angular data obtained by processing modulated directive electromagnetic signals emitted by at least two fixed rotating transmitters, and includes the operative steps of: dividing the 360.degree. of the rotation into 2.sup.n angular values, n being an integer; generating a coding sequence of 2.sup.n binary configurations of n bits successively overlapping for n-1 bits, whereby the n bits of each of the 2.sup.n configurations in the sequence are the n-1 last bits of the preceding configuration plus one more bit, the coding sequence being made up of 2.sup.n +(n-1) bits; generating a coding pattern wherein said angular values are coded by successively assigning to each of them one of the 2.sup.n binary values corresponding to the successive 2.sup.n configurations of n bits making up said coding sequence; storing the coding pattern in the transmitters and in the receiver; starting the rotations of the at least two transmitters at a constant speed and correlated so as to avoid the receiver from being swept simultaneously by both directive transmissions emitted by the transmitters; transmitting the angular data corresponding to the direction of emission of the beams by reading the coding sequence 1 bit at a time after the first n bits, the carrier wave signal being modulated according to the reading;
REFERENCES:
patent: 3818478 (1974-06-01), Groginsky
patent: 4007991 (1977-02-01), Robertson
patent: 4564841 (1986-01-01), Neidell
Milani Carlo
Moretto Gianantonio
Hellner Mark
Milani Carlo
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