Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1999-12-01
2001-06-19
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S214000, C342S357490, C342S357490, C356S370000
Reexamination Certificate
active
06249743
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for identifying a position of an automated guided movable body such as an automated guided vehicle on a field inside or outside of a factory, and to an apparatus of detecting a position of a movable body to be used in carrying out the method.
An automated guided vehicle is often used for transporting goods in a factory. In order to control travelling of the automated guided vehicle, it is necessary to identify the position and the travelling direction of the automated guided vehicle by means of a position detecting apparatus.
A movable body position detecting method and apparatus for identifying the position and the travelling direction of a movable body is disclosed, for example, in Japanese Patent Application Laid-open No. 09-105628/1997.
FIG. 1
is a block diagram showing a construction of the movable body position detecting apparatus disclosed in Japanese Patent Application laid-open No. 09-105628/1997.
FIG. 2
is a perspective view showing an overall construction of the apparatus. The movable body position detecting apparatus includes a recognizing and identifying circuit
20
provided with a recognizing means
211
and a position calculating means
24
, and an optical unit
10
disposed before the recognizing and identifying circuit
20
. The position of a truck
30
, which is a movable body, is detected by detecting the reflectors Hi by the optical unit
10
and analyzing the detection results by the recognizing and identifying circuit
20
.
Three or more reflectors Hi are mounted on wall surfaces of a travelling area of the movable body. The reflectors Hi are formed by separately painted reflecting portions and non-reflecting portions so as to provide respective specific barcode-like marks formed by the reflecting portions and the non-reflecting portions arranged as horizontal bars with intervals and thicknesses different from each other.
FIG. 3
is an enlarged vertical cross-sectional view showing a construction of an essential part of the optical unit
10
. The optical unit
10
is mounted on the truck
30
via a frame
31
, and includes a laser oscillator
11
for outputting a laser light, an image sensor
121
for receiving the laser light reflected from the outside, a horizontally rotating turn table
131
for mounting these elements, and other elements. A tubular polygon mirror
17
having a regular polygonal shape in its vertical cross section and formed by a combination of a plurality of mirror plates
17
c
is mounted in front of the laser oscillator
11
so as to be vertically rotatable. A cover
131
c
for cutting off the outside light is mounted on the upper surface of the turn table
131
, and an aperture
131
c
1
is disposed in a side surface of the cover
131
c
for irradiating and receiving the laser light.
The laser light irradiated from the laser oscillator
11
and reflected by the polygon mirror
17
travels through a half mirror
17
b
and is reflected by a tilted mirror
17
a
to exit through the aperture
131
c
to the outside. The laser light is reflected by the reflector Hi and passes through the aperture
131
c
1
to be reflected by the tilted mirror
17
a
and the half mirror
17
b
to be incident into the image sensor
121
.
Since the polygon mirror
17
is rotating, the laser light exiting through the aperture
131
c
1
moves downwards by a predetermined distance while the laser light is hitting one mirror plate
17
c
. Further, since the optical unit
10
is rotated by means of the turn table
131
, the laser light is also rotated to irradiate surroundings of the truck
30
.
The laser light is reflected only when the laser light passes the reflector Hi, and the reflected light is incident into the image sensor
121
. Also, since the irradiation of the laser light changes downwards, the reflector Hi is scanned over its entire width in the vertical direction. The data of the pattern of the scanned reflector Hi are input from the image sensor
121
to the recognizing means
211
. The reflector Hi is identified by making reference to the data of the patterns previously stored in a storage means
221
, and its coordinate values are obtained. In addition, an output at the scanning time from an encoder
15
mounted on a rotating shaft of the turn table
131
is input into an angle calculating means
25
to calculate an angle &thgr;i of the direction of the reflector Hi relative to a reference direction.
Hereafter, a procedure for identifying the position of the movable body will be explained.
FIG. 4
is an explanatory view showing positional relationship between the movable body and the scanned three reflectors.
FIG. 5
is an explanatory view showing a procedure for identifying the position according to the prior art. Three or more reflectors Hi are scanned in the above-mentioned manner to determine their coordinate values Ai and their angles &thgr;i relative to the reference direction. From the coordinate values Ai of the scanned reflectors Hi, three points A
1
, A
3
, A
5
are selected, and the two points A
1
, A
3
and the two points A
3
, A
5
are respectively connected with a line. Here, the three points A
1
, A
3
, A
5
are selected so that the angle &thgr;k at each point satisfies 0°<&thgr;k<180°. Two circles E
1
a
, E
1
b
and two circles E
2
a
, E
2
b
are determined having the lines as their chords and having the angle &thgr;a between A
1
and A
3
and the angle &thgr;b between A
3
and A
5
as their angles of circumference.
The intersecting points of the circles E
1
a
, E
1
b
, E
2
a
, E
2
b
are determined, and four points P
1
, P
2
, P
3
, P
4
other than A
1
, A
3
, A
5
are determined. The position of the truck
30
can be identified as one of the intersecting points P
1
, P
2
, P
3
, P
4
. For example, in order that the intersecting point P
1
of the circles E
1
a
, E
2
a
is appropriate as representing the position of the truck
30
, the intersecting point P
1
must satisfy the following conditions simultaneously.
1. The coordinates of the intersecting point P
1
lie within an area that the truck
30
can travel.
2. The intersecting point P
1
lies on the same side as the center T
1
a
of the circle E
1
a
relative to the line segment connecting the points A
1
, A
3
if the angle &thgr;a<90°, and lies on the different side from the center T
1
a
relative to the line segment connecting the points A
1
, A
3
if the angle &thgr;a>90°.
3. The intersecting point P
1
lies on the same side as the center T
2
a
of the circle E
2
a
relative to the line segment connecting the points A
3
, A
5
if the angle &thgr;b<90°, and lies on the different side from the center T
2
a
relative to the line segment connecting the points A
3
, A
5
if the angle &thgr;b>90°.
4. The points A
1
, A
3
, A
5
are arranged clockwise in this order from the reference direction with the intersecting point P
1
being the center when scanned clockwise.
Here, the conditions
2
,
3
are based on the fact that the intersecting point P
1
is an intersecting point of the circles E
1
a
, E
2
a
. Therefore, the one point appropriate as the position of the truck
30
can be identified by observing the fact that the intersecting point P
2
is the intersecting point of the circles E
1
b
, E
2
b
, the intersecting point P
3
is the intersecting point of the circles E
1
b
, E
2
a
, and the intersecting point P
4
is the intersecting point of the circles E
1
a
, E
2
b
, and examining whether similar conditions are satisfied at each intersecting point. Also, the direction of the truck
30
can be determined on the basis of the angle &thgr;
1
of the coordinates A
1
relative to the reference direction N as viewed from the intersecting point P
1
thus identified.
In the meantime, according to the conventional movable body position detecting method and apparatus as described above, the position of the movable body is identified based on triangulation, so that it is necessary to determine which of the reflectors numerously disposed in the moving area the detected reflector is. For this re
Beaulieu Yonel
Cuchlinski Jr. William A.
Darby & Darby
Tsubakimoto Chain Co.
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