Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Automatic route guidance vehicle
Reexamination Certificate
1999-04-13
2001-06-12
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Automatic route guidance vehicle
C701S026000, C701S002000, C701S011000, C342S046000, C340S901000, C340S933000, C340S988000, C340S425500
Reexamination Certificate
active
06246930
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an automatic guided vehicle system and a method for navigating an automatic guided vehicle using this system, and more specifically, the present invention relates to the system and method for enabling the present position to be recognized at an arbitrary position without temporarily determining the initial position of automatic guided vehicles.
BACKGROUND OF THE INVENTION
In the prior art, there is a system in which a plurality of reflectors are disposed along the travelling path, and the reflectors are recognized by means of a laser scanner on an automatic guided vehicle to calculate their present position. When three reflectors can be recognized, the present position can be calculated using the principle of triangulation, therefore, the problem with this approach is that concerning whether such recognized reflector is to be specified which of the reflectors on the reflector map. In this case, this problem can be easily solved by assigning identification data such as bar codes to the reflectors, however, such reflectors are expensive and require much time to install. Therefore, in general, the reflectors must be identical.
In order to specify a reflector without assigning identification data to the reflector itself, the start position of an automatic guided vehicle is input to the automatic guided vehicle. First, presuming that the automatic guided vehicle starts from a known position, the recognized reflector is specified at the starting time. In subsequent recognition, the present position is assumed from the previous recognized position, and assuming that the reflector can be recognized for that position is recognized, the reflector is specified.
However, when using this technique, if a reflector is incorrectly recognized, it becomes impossible to recognize the exact position of the automatic guided vehicle, thus making it uncontrollable. In addition, it is time-consuming to input the present position during at the starting time. For example, presuming that the automatic guided vehicle starts up from a specific reset position, the automatic guided vehicle is manually driven and started up to that position, or it becomes necessary to manually input the present position at each position on the site. In any case, such work is time-consuming.
It is an object of the present invention to start up the automatic guided vehicle to an autonomous travelling without initial position data.
It is another object of the present invention to reduce the error rate of the recognized initial position of the automatic guided vehicle to a negligible value.
It is still another object of the present invention to provide a specific technique for obtaining the initial position of the automatic guided vehicle with a very low error rate.
SUMMARY OF THE INVENTION
The present invention is directed to an automatic guided vehicle system wherein a plurality of reflectors are disposed along the travelling path, and the automatic guided vehicle has a laser scanner for obtaining the orientation and distance of reflectors, a reflector map, a means for temporarily specifying three reflectors comparing recognition values of the distances of the recognized three reflectors with the reflector map, and a means for obtaining the present position of the automatic guided vehicle based on the temporary specification.
Preferably, a means for checking the conformity of the temporary specification from the recognition value of the fourth and subsequent reflectors is also provided.
The present invention is directed to a method for navigating automatic guided vehicles wherein a plurality of reflectors are disposed along the travelling path, and the orientation and distance of at least three reflectors are recognized by means of the laser scanner on the automatic guided vehicle, and the recognized distance is compared with the reflector map to temporarily specify the reflectors, and the present position of the automatic guided vehicle is temporarily obtained based on the temporarily specified reflectors, and the present position is obtained by confirming the temporarily obtained present position from the recognition value of the fourth and subsequent reflectors.
In the automatic guided vehicle system of the present invention, with respect to three reflectors recognized by the laser scanner mounted on the automatic guided vehicle, a permissible combination of the reflectors on the reflector map is temporarily specified from information on the distance between the reflector and the laser scanner. Then, in the case where the fourth and subsequent reflectors can be recognized, the reflectors are completely specified using that information. Even if only three reflectors are recognized, in the case where the other summary information on the initial position of the automatic guided vehicle is given, b using such information, and, in the case where the information on the position of the reflector is given, such as which of the left and right of the travelling path of the automatic guided vehicle each reflector is present, by using such information, the present position of the automatic guided vehicle temporarily obtained is confirmed. Therefore, the automatic guided vehicle can be started up without the information on the initial position of the automatic guided vehicle.
Here, in the case where the fourth end subsequent reflectors can be recognized, the additional information obtained by that are an orientation and a distance, and in general, the laser scanner provides very high anglular resolution, therefore, it can eliminate errors thoroughly. Moreover, if the information on the distance of the fourth reflector is used, the present position can be recognized with greater precision. In the case where the fourth and subsequent reflectors can be recognized, with respect to the fourth and subsequent reflectors, the present position can be recognized by using only an angle information instead of by using the information on both angle and distance.
In addition, the term “three reflectors” or the term “foruth and subsequent reflectors” does not limit to use the firstly recognized three reflectors for temporary position precognition, and to use the fourth and subsequent recognized reflectors for confirming the conformity. For example, in the case where four reflectors are recognized, the second reflector may be used for confirming the conformity, and the present position may be temporarily specified by the first, third and fourth reflectors.
In the present invention, in the case where the automatic guided vehicle can be transferred to autonomous travelling without the initial position information, and in the case where there arises a problem concerning the present position of the automatic guided vehicle after starting autonomous travelling, the position of the automatic guided vehicle can again be precisely obtained. Therefore, the present invention eliminates the problem of having to start up the automatic guided vehicle at only a specific position and of having to input the exact initial position to the automatic guided vehicle.
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Armstrong Westerman Hattori McLeland & Naughton LLP
Cuchlinski Jr. William A.
Hernandez Olga
Murata Kikai Kabushiki Kaisha
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