WO2011163209A2

WO2011163209A2 - Mobile object control system and program, and mobile object control method

Info

Publication number: WO2011163209A2
Application number: PCT/US2011/041222
Authority: WO
Inventors: Masaaki Ikeda
Original assignee: Cognex Corporation
Priority date: 2010-06-23
Filing date: 2011-06-21
Publication date: 2011-12-29
Also published as: JP2012007934A; WO2011163209A3; JP5634764B2

Abstract

The problem for the present invention is, in a mobile object control system that controls a mobile object on the basis of images captured by a plurality of image capturing units, to enhance the accuracy of the correspondence relationships between the respective image capture coordinate systems that are determined for the respective image capturing units. And, according to the present invention, a first rotational center position specification unit specifies a first rotational center position in a first image capture coordinate system corresponding to a first point on the basis of respective first reference guide marks included in respective first images. Moreover, a second rotational center position specification unit specifies a second rotational center position in a second image capture coordinate system corresponding to the first point on the basis of respective second reference guide marks included in respective second images. And, on the basis of the first rotational center position and the second rotational center position, a coordinate system correspondence relationship storage unit stores a coordinate system correspondence relationship that specifies the correspondence relationship between the first image capture coordinate system and second image capture coordinate system.

Description

MOBILE OBJECT CONTROL SYSTEM AND PROGRAM, AND MOBILE OBJECT CONTROL METHOD

FIELD OF THE INVENTION

The present invention relates to a mobile object control system and program, and to mobile object control method.

BACKGROUND ART

In JP 3,531,674B, there is disclosed a position determination device that determines the position of a subject for positional determination. This position determination device captures, with a plurality of cameras, images including marks provided upon such a subject that is installed upon a table, while shifting the table. And, using these images, this position determination device calculates the amounts of deviation between the positions of the marks and the target positions of the marks, and rotates the table or shifts it parallel to itself until these deviations are cancelled. Moreover in JP 2006-49755 A, there is disclosed a workpiece position determination device that specifies the coordinates of the rotational center of a stage which are required in order to correct rotational deviation of the workpiece. This workpiece position determination device measures coordinates that specify the positions of marks from images that are obtained by image capture twice by two cameras. And this workpiece position determination device calculates the rotational angle of the stage by using the shift amounts of the marks (which are obtained from their coordinates) and the distance between the marks (which is inputted in advance), and calculates the rotational center of the stage using this rotational angle and the coordinates of the marks. And in JP 5-48295A, there is disclosed an electronic device installation device that installs chip type electronic devices in predetermined positions upon an electronic circuit board. With this electronic device installation device, the attitudes of the electronic devices are corrected by rotating suction nozzles on the basis of positional data for the suction nozzles which is inputted in advance, and on the basis of reference positions for the electronic devices that are determined based upon images captured by a camera. SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

Now, with a mobile object control system that controls a mobile object on the basis of images captured by a plurality of image capturing units, when the accuracy of the correspondence relationship between the image capture coordinate systems that are determined for each of the image capturing units is poor, it takes a long period of time to shift the object to its target position.

Thus, with a mobile object control system that controls a mobile object on the basis of images captured by a plurality of image capturing units, there is a demand for

enhancement of the accuracy of the correspondence relationship between the image capture coordinate systems that are determined for each of the image capturing units.

MEANS FOR SOLVING THE PROBLEMS

A mobile object control system according to an embodiment of the present invention comprises: a first image acquisition unit that, when a mobile object is rotated around an arbitrary first point as center that is within a first image capturing range of a first image capturing unit that captures first images including a first reference guide mark provided in advance upon the mobile object, acquires the first images captured by the first image capturing unit before rotation and after rotation; a second image acquisition unit that, when the mobile object is rotated around the first point as center, acquires second images captured by a second image capturing unit that captures second images including a second reference guide mark provided in advance upon the mobile object before and after rotation; a first rotational center position specification unit that, on the basis of the first reference guide marks included in each of the first images, specifies a first rotational center position corresponding to the first point in a first image capture coordinate system that is determined in advance with respect to the first image capturing unit; a second rotational center position specification unit that, on the basis of the second reference guide marks included in each of the second images, specifies a second rotational center position corresponding to the first point in a second image capture coordinate system that is determined in advance with respect to the second image capturing unit; and a coordinate system correspondence relationship storage unit that, on the basis of the first rotational center position and the second rotational center position, maintains a coordinate system correspondence relationship that specifies a correspondence relationship between the first image capture coordinate system and the second image capture coordinate system.

With the mobile object control system described above: the first image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of first points within the first image capturing range as center, may acquire the first images captured by the first image capturing unit both before rotation and after rotation; the second image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of first points within the first image capturing range as center, may acquire the second images captured by the second image capturing unit both before rotation and after rotation; the first rotational center position specification unit may specify each of the first rotational center positions corresponding to each of the first points on the basis of the first reference guide marks included in each of the first images before rotation and after rotation; the second rotational center position specification unit may specify each of the second rotational center positions corresponding to each of the first points on the basis of the second reference guide marks included in each of the second images before rotation and after rotation; and the coordinate system correspondence relationship storage unit may maintain the coordinate system correspondence relationship on the basis of each of the first rotational center position and the second rotational center position.

With the mobile object control system described above: when the mobile object is rotated around any arbitrary second point within the second image capturing range of the second image capturing unit as center, the first image acquisition unit may acquire the first images captured by the first image capturing unit before and after rotation; when the mobile object is rotated around the second point as center, the second image acquisition unit may acquire the second images captured by the second image capturing unit before and after rotation; the first rotational center position specification unit may specify the first rotational center position corresponding to the second point in the first image capture coordinate system on the basis of the first reference guide marks included in each of the first images before and after rotation; the second rotational center position specification unit may specify the second rotational center position corresponding to the second point in the second image capture coordinate system on the basis of the second reference guide marks included in each of the second images before and after rotation; and the coordinate system correspondence relationship storage unit may maintain the coordinate system correspondence relationship on the basis of the first rotational center position and the second rotational center position corresponding to the second point.

With the mobile object control system described above: the first image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of second points within the second image capturing range as center, may acquire the first images captured by the first image capturing unit both before rotation and after rotation; the second image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of second points within the second image capturing range as center, may acquire the second images captured by the second image capturing unit both before rotation and after rotation; the first rotational center position specification unit may specify each of the first rotational center positions corresponding to each of the second points on the basis of the first reference guide marks included in each of the first images before rotation and after rotation; the second rotational center position specification unit may specify each of the second rotational center positions corresponding to each of the second points on the basis of the second reference guide marks included in each of the second images before rotation and after rotation; and the coordinate system correspondence relationship storage unit may maintain the coordinate system correspondence relationship on the basis of the first rotational center positions and the second rotational center positions corresponding to each of the second points.

With the mobile object control system described above, there may be further included: a position specification unit that, by referring to the coordinate system

correspondence relationship, specifies a first position of the first guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to an object held by the mobile object that is included in the first image captured by the first image capturing unit, and a second position of the second guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to the object that is included in the second image captured by the second image capturing unit; and a shift mechanism control unit that, on the basis of an angle subtended by a straight line that connects the first position and the second position in the first image capture coordinate system or the second image capture coordinate system and a target line that is determined in advance in the first image capture coordinate system or the second image capture coordinate system, rotates the mobile object via a shift mechanism around a point as center that is determined in advance within the first image capturing range of the first image capturing unit or within the second image capturing range of the second image capturing unit, so as to shift the object to a target position.

With the mobile object control system described above, the shift mechanism control unit may shift the object to the target position by rotating the mobile object via the shift mechanism around a point as center determined on the basis of the first guide mark or the second guide mark.

With the mobile object control system described above, the shift mechanism may comprise two first direction shift mechanisms that shift the mobile object parallel to itself in a first direction that is determined in advance, and a second direction shift mechanism that shifts the mobile object parallel to itself in a second direction that is different from the first direction; and the shift mechanism control unit may rotate the mobile object by controlling each of the two first direction shift mechanisms and the second direction shift mechanism.

With the mobile object control system described above, there may be further included: a ratio acquisition unit that, when the mobile object has been shifted parallel to itself by an arbitrary distance, acquires the ratio between the actually measured value of the shift distance of the first reference guide mark in the first image capture coordinate system and the actually measured value of the shift distance of the second reference guide mark in the second image capture coordinate system, before parallel shifting and after parallel shifting; a correction coefficient specification unit that specifies a correction coefficient on the basis of the ratio of the actually measured values; and a parallel shift amount specification unit that, when the object is to be shifted to the target position, specifies a parallel shift amount for the mobile object on the basis of the correction coefficient.

With the mobile object control system described above, there may be further included a rotational angle correspondence relationship storage unit that maintains a rotational angle correspondence relationship that specifies a correspondence relationship between a rotational angle in the first image capture coordinate system or the second image capture coordinate system specified on the basis of the first reference guide mark or the second reference guide mark respectively included in the first image or the second image, and a rotational angle in a mobile object coordinate system that is determined in advance with respect to the mobile object, when the mobile object is rotated a plurality of times about an arbitrary point as center. And a mobile object control system according to an embodiment of the present invention comprises: a coordinate system correspondence relationship storage unit that maintains a coordinate system correspondence relationship that specifies a correspondence relationship between an image capture coordinate system determined in advance with respect to an image capturing unit that captures an image including a reference guide mark determined in advance with respect to a mobile object, and a mobile object coordinate system determined in advance with respect to the mobile object; a designated coordinate values specification unit that specifies the coordinate values of an arbitrary point in the image capture coordinate system within the image capturing range or outside the image capturing range as designated coordinate values; an image acquisition unit that specifies coordinate values in the mobile object coordinate system corresponding to the designated coordinate values on the basis of the coordinate system correspondence relationship, and, when the mobile object is rotationally shifted through an arbitrary rotational angle around the specified coordinate values as center, acquires the images captured by the image capturing unit both before shifting and after shifting; a rotational center position specification unit that specifies, as rotational center coordinate values, coordinate values in the image capture coordinate system with respect to the rotational center position of the mobile object, on the basis of the reference guide marks included in each of the images, and the rotational angle; and a correspondence relationship correction unit that corrects the coordinate system

correspondence relationship on the basis of the coordinate values in the mobile object coordinate system and the rotational center coordinate values.

With the mobile object control system described above, the image acquisition unit, when the mobile object is rotationally shifted through arbitrary rotational angles a plurality of times around the specified coordinate values as center, may acquire three or more of the images captured by the image capturing unit before shifting and after shifting; and the rotational center position specification unit may specify, as rotational center coordinate values, coordinate values in the image capture coordinate system with respect to the position of the rotational center of the mobile object on the basis of the respective reference guide marks included in each of the images, and the rotational angles.

With the mobile object control system described above, the designated coordinate values specification unit may specify a plurality of the designated coordinate values; the image acquisition unit may specify respective coordinate values in the mobile object coordinate system corresponding to the plurality of designated coordinate values on the basis of the coordinate system correspondence relationship, and, when the mobile object is rotationally shifted through an arbitrary rotational angle around the specified coordinate values as center, may acquire the images captured by the image capturing unit before shifting and after shifting; the rotational center position specification unit, for each of the plurality of designated coordinate values, may specify coordinate values in the image capture coordinate system with respect to the rotational center position of the mobile object as rotational center coordinate values, on the basis of the reference guide marks included in each of the images, and the rotational angles; and the correspondence relationship correction unit may correct the coordinate system correspondence relationship on the basis of the specified coordinate values and the corresponding rotational center coordinate values.

With the mobile object control system described above, the designated coordinate values specification unit may specify a plurality of the designated coordinate values corresponding to coordinate values that are arranged upon a straight line determined in advance in the image capture coordinate system; and the correspondence relationship correction unit may correct the plurality of rotational center coordinate values specified for each of the plurality of designated coordinate values on the basis of the coordinate values arranged upon a straight line, and may correct the coordinate system correspondence relationship on the basis of the specified coordinate values and the rotational center coordinate values after amendment.

With the mobile object control system described above, the image acquisition unit may comprise a first image acquisition unit that, when the mobile object is rotated around the designated coordinate values as center, acquires the first images captured by the first image capturing unit that captures a first image including a first reference guide mark determined in advance with respect to the mobile object, both before and after rotation, and a second image acquisition unit that, when the mobile object is rotated around the designated coordinate values as center, acquires the second images captured by the second image capturing unit that captures a second image including a second reference guide mark determined in advance with respect to the mobile object, both before and after rotation; the coordinate system

correspondence relationship storage unit may maintain a correspondence relationship between a first image capture coordinate system of the first image capturing unit and a second image capture coordinate system of the second image capturing unit; and the rotational center position specification unit may specify a single the rotational center coordinate value in either one of the image capture coordinate systems on the basis of the respective rotational center coordinate values in the first image capture coordinate system and the second image capture coordinate system, specified separately on the basis of the first reference guide mark included in the first image and the second reference guide mark included in the second image.

With the mobile object control system described above, the image acquisition unit may comprise a first image acquisition unit that, when the mobile object is rotated around the designated coordinate values as center, acquires the first images captured by the first image capturing unit that captures a first image including a first reference guide mark determined in advance with respect to the mobile object, both before and after rotation; and a second image acquisition unit that, when the mobile object is rotated around the designated coordinate values as center, acquires the second images captured by the second image capturing unit that captures a second image including a second reference guide mark determined in advance with respect to the mobile object, both before and after rotation; the coordinate system

correspondence relationship storage unit may maintain a correspondence relationship between the first image capture coordinate system of the first image capturing unit and the second image capture coordinate system of the second image capturing unit; and the designated coordinate values specification unit may specify, as designated coordinate values, an arbitrary point upon the perpendicular bisector of a line segment that connects an arbitrary point specified on the basis of the first reference guide mark and an arbitrary point specified on the basis of the second reference guide mark.

correspondence relationship, specifies a first position of a first guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to an object held by the mobile object that is included in the first image captured by the first image capturing unit, and a second position of a second guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to the object that is included in the second image captured by the second image capturing unit; and a shift mechanism control unit that, on the basis of an angle subtended by a straight line that connects the first position and the second position in the first image capture coordinate system or the second image capture coordinate system and a target line that is determined in advance in the first image capture coordinate system or the second image capture coordinate system, rotates the mobile object via a shift mechanism around any arbitrary point as center within the first image capturing range or outside the image capturing range, so as to shift the object to a target position.

Moreover, the mobile object control system according to an embodiment of the present invention may include: a coordinate system correspondence relationship storage unit that maintains a coordinate system correspondence relationship specifying a correspondence relationship between an image capture coordinate system determined in advance with respect to an image capturing unit that captures an image including a reference guide mark determined in advance with respect to a mobile object, and a mobile object coordinate system determined in advance with respect to the mobile object; a designated coordinate values specification unit that specifies, as designated coordinate values, coordinate values of an arbitrary point within the image capturing range of the image capture coordinate system, or outside the image capturing range; an image acquisition unit that, on the basis of the coordinate system correspondence relationship, specifies coordinate values in the mobile object coordinate system that correspond to the designated coordinate values, and, when the mobile object is rotational shifted through any arbitrary rotational angle around the specified coordinate values as center, acquires the images captured by the image capturing unit before shifting and after shifting; a rotational center position specification unit that specifies coordinate values in the image capture coordinate system with respect to the rotational center position of the mobile object as rotational center coordinate values, on the basis of the reference guide marks included in each of the images and the rotational angle; and a correspondence relationship correction unit that corrects the coordinate system

correspondence relationship on the basis of the rotational center coordinate values and the designated coordinate values; wherein, when the mobile object shifts in a combination of rotational shifting through any arbitrary rotational angle and shifting parallel to itself, the image acquisition unit acquires the image including the reference guide mark at both time points, before shifting or after shifting.

With the mobile object control system described above, there may be further included a rotational angle correspondence relationship storage unit that maintains a rotational angle correspondence relationship that specifies a correspondence relationship between a rotational angle in the image capture coordinate system specified on the basis of the reference guide marks respectively included in the images, when the mobile object is rotated a plurality of times around an arbitrary point as center, and a rotational angle in a mobile object coordinate system.

It should be understood that sub-combinations of these characteristic groups are also embraced within the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows an example of the structure of a mobile object control system according to one embodiment of the present invention;

Fig. 2 shows examples of a first image and a second image that include a first target mark and a second target mark;

Fig. 3 shows functional blocks of this mobile object control system;

Fig. 4 is a flow chart showing an example of a procedure when a calibration unit acquires a coordinate system correspondence relationship;

Fig. 5 is a flow chart showing an example of a procedure for performing alignment in order for an alignment unit to shift an object to its target position; and

Fig. 6 shows functional blocks of a mobile object control system according to another embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS FOR IMPLEMENTATION OF THE INVENTION

While the present invention will be explained in the following in terms of several embodiments thereof, the following embodiments are not to be considered as limiting the scope of the present invention in any way; rather, this is to be determined according to the Claims. Moreover, all the combinations of characteristics explained in the embodiments are not limitative or essential to the means of solution provided by the present invention.

Fig. 1 is a figure showing an example of the structure of a mobile object control system 100 according to one embodiment of the present invention. This mobile object control system 100 comprises a stage 10, a shift mechanism 30, a first image capturing unit 40-1, a second image capturing unit 40-2, and a shift mechanism control device 50. The stage 10 functions as a mobile object that supports an object 20, so that this object 20 is installed upon the stage 10. The shift mechanism 30 drives the stage 10 to shift in horizontal directions, in other words in the X and Y directions in Fig. 1, and in the rotational direction, in other words in the Θ direction, which is rotation around an arbitrary rotation axis in the Z direction in Fig. 1 as center.

The first image capturing unit 40-1 captures an image that includes one corner portion 20a of the object 20, and this may be considered as being an image that includes a first guide mark that is determined in advance with respect to the object 20 upon the stage 10. In some cases an image that is captured by the first image capturing unit 40-1 may be called a "first image". It should be understood that, in this embodiment, the vertex 20b of the corner portion 20a indicates the first guide mark.

And the second image capturing unit 40-2 captures an image that includes another corner portion 20c of the object 20, and this may be considered as being an image that includes a second guide mark that is determined in advance with respect to the object 20 upon the stage 10. In some cases an image that is captured by the second image capturing unit 40-2 may be called a "second image". It should be understood that, in this embodiment, the vertex 20d of the corner portion 20c indicates the second guide mark.

On the basis of the first guide mark in the first image and the second guide mark in the second image, the shift mechanism control device 50 controls the shifting of the stage 10 via the shift mechanism 30, so as to shift the object 20 to a target position that is determined in advance.

Furthermore, with the mobile object control system 100 according to this

embodiment, a coordinate system correspondence relationship is acquired with good accuracy, specifying the correspondence relationship between a first image capture coordinate system that is determined in advance with respect to the first image capturing unit 40-1 and a second image capture coordinate system that is determined in advance with respect to the second image capturing unit 40-2. With the mobile object control system 100 according to this embodiment, by referring to this coordinate system correspondence relationship, the position of the first guide mark that is included in the first image and the position of the second guide mark that is included in the second image are both acquired as coordinate values in either the first image capture coordinate system or the second image capture coordinate system. Moreover, on the basis of these coordinate values, the mobile object control system 100 causes the object 20 to be shifted to its target position by rotating the object 20 around, as center, a point within the first image capturing range of the first image capturing unit 40-1 or within the second image capturing range of the second image capturing unit 40-2.

It should be understood that, in this embodiment, an example is explained in which the shifting of the object 20 is performed by shifting the stage 10 in the horizontal directions or in the rotational direction. However, this shifting of the object 20 could also be performed without necessarily shifting the stage 10. For example, it would be acceptable to suck down the object 20 with a suction device that is installed on the upper portion of the stage 10, so as to hold it to the stage 10, and to make the object 20 shift by shifting the suction device in horizontal directions or in the rotational direction. In other words, in this case, the suction device would function as a mobile object.

Fig. 2 shows examples of a first image and a second image that include a first target mark and a second target mark, captured by the first image capturing unit 40-1 and by the second image capturing unit 40-2 respectively. The reference symbol 200 denotes the first image, while the reference symbol 210 denotes the second image. Moreover a straight line drawn between the vertex 20b which is the first guide mark, and the vertex 20d which is the second guide mark, is denoted by the reference symbol 220. Furthermore, a target position for the first guide mark is denoted by the reference symbol 204, while a target position for the second guide mark is denoted by the reference symbol 214. Yet further, a target line that will be described hereinafter is denoted by the reference symbol 230. The angle subtended by the straight line 220 and the target line 230 is denoted by the reference symbol 222. With the mobile object control system 100 according to this embodiment, the mobile object control system 100 controls the stage 10 so as to shift the object 20 to an object 20' in a target position shown by the single dotted broken lines.

Fig. 3 shows the functional blocks of this mobile object control system 100. Via the first image acquisition unit 42-1, the first image capturing unit 40-1 supplies the first image to the calibration unit 60 and to the alignment unit 70. In the same manner, via the second image acquisition unit 42-2, the second image capturing unit 40-2 supplies the second image to the calibration unit 60 and to the alignment unit 70.

The shift mechanism 30 comprises a first X direction shift mechanism 32 and a second X direction shift mechanism 34 that shift the stage 10 parallel to itself in the X direction, and a Y direction shift mechanism 36 that shifts the stage 10 parallel to itself in the Y direction. This shift mechanism 30 is a so called U-V-W stage control mechanism that is shiftable in a first direction and in a second direction that is different from the first direction, and performs parallel shifting of the stage 10 in the X direction and in the Y direction and rotational shifting in the Θ direction by controlling each of the first X direction shift mechanism 32, the second X direction shift mechanism 34, and the Y direction shift mechanism 36. It should be understood that in this embodiment, as mentioned above, an example of this shift mechanism 30 is explained which is a U-V-W stage control mechanism. However, it would also be acceptable for the shift mechanism 30, for example, to be a so called X-Υ-θ stage control mechanism comprising a parallel shift mechanism that parallel shifts the stage 10 in the X direction and in the Y direction, and a rotational shift mechanism that is shiftable by the parallel shift mechanism in the X direction and in the Y direction and that moreover rotationally shifts the stage 10 in the Θ direction.

The shift mechanism control device 50 comprises a first image acquisition unit 42-1, a second image acquisition unit 42-2, a calibration unit 60, a coordinate system

correspondence relationship storage unit 66, an alignment unit 70, a target position storage unit 78, and a shift mechanism control unit 80.

The first image acquisition unit 42-1 acquires the first image captured by the first image capturing unit 40-1, and supplies this first image that it has acquired to the calibration unit 60 and the alignment unit 70. And the second image acquisition unit 42-2 acquires the second image captured by the second image capturing unit 40-2, and supplies this second image that it has acquired to the calibration unit 60 and the alignment unit 70.

The calibration unit 60 performs calibration on the basis of the shift trajectories of the first reference guide mark and the second reference guide mark that are determined in advance upon the stage 10 and that are included in the first image and in the second image. In other words, the calibration unit 60 acquires a coordinate system correspondence relationship that specifies the positional relationships between the stage 10 and the first image capturing unit 40-1 and the second image capturing unit 40-2, in other words, that specifies the relationships between the orthogonal coordinate system of the stage 10 (sometimes this is termed the "stage coordinate system") and the first image capture coordinate system and the second image capture coordinate system, which are orthogonal coordinate systems for the image capturing ranges of the first image capturing unit 40-1 and the second image capturing unit 40-2. Furthermore, the calibration unit 60 acquires a coordinate system correspondence relationship that specifies the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system at the rotational center when the stage 10 is rotated around any arbitrary first point that is included in the image capturing range of the first image capturing unit 40-1 as center. It should be understood that the first reference guide mark and the second reference guide mark may be points that are affixed to the stage 10 in advance.

The coordinate system correspondence relationship storage unit 66 maintains the coordinate system correspondence relationship that has been acquired by the calibration unit 60.

The alignment unit 70 comprises a position specification unit 72, a parallel shift amount specification unit 74, and a rotation amount specification unit 76, and performs alignment so as to shift the object 20 to its target position on the basis of the first guide mark included in the first image, which is determined in advance upon the object 20, and the second guide mark included in the second image, which is likewise determined in advance upon the object 20.

On the basis of the first image, the position specification unit 72 specifies the X-Y coordinate values of the first guide mark in the first image capture coordinate system.

Moreover, along with specifying the X-Y coordinate values of the second guide mark in the second image capture coordinate system on the basis of the second image, the position specification unit 72 also specifies the X-Y coordinate values in the first image capture coordinate system of those X-Y coordinate values by referring to the coordinate system correspondence relationship. And the parallel shift amount specification unit 7 specifies parallel shift amounts for the stage 10 in the X direction and in the Y direction in order to shift the object 20 to its target position. Furthermore, the rotational amount specification unit specifies a rotation amount for the stage 10 in the Θ direction in order to shift the object 20 to its target position.

Fig. 4 is a flow chart showing an example of the procedure when, during calibration, the calibration unit 60 acquires the coordinate system correspondence relationship. The calibration unit 60 acquires a first coordinate system correspondence relationship between the first image capture coordinate system and the stage coordinate system on the basis of the first reference guide mark that is included in the first image. Moreover, on the basis of the first reference guide mark that is included in the first image, the calibration unit 60 acquires a dummy first rotational center position of the first image capture coordinate system when the stage is rotated with the shift mechanism 30 is in its set initial position (step SI 00).

In more concrete terms, the calibration unit 60 first commands the shift mechanism control unit 80 to shift the stage 10 to its set initial position. After the stage 10 has been shifted to its set initial position, the calibration unit 60 repeatedly shifts the stage 10 by parallel shift amounts in the X and the Y direction that are determined in advance, and, each time, acquires X-Y coordinate values in the first image capture coordinate system of the first reference guide mark included in the first image. And the calibration unit 60 establishes a correspondence between the X-Y coordinate values of the stage coordinate position with respect to its set initial position that are acquired each time, and the X-Y coordinate values in the first image capture coordinate system, and stores this in the coordinate system

correspondence relationship storage unit 66 as a first coordinate system correspondence relationship. In a similar manner, the calibration unit 60 can also acquire a second coordinate system correspondence relationship between the second image capture coordinate system and the stage coordinate system, on the basis of the second reference guide mark that is included in the second image. It should be understood that it will be supposed that what is meant by the coordinate values of a reference guide mark is the overall attitude of the reference guide mark as expressed in the image capture coordinate system, and in some cases this means the coordinate position of a specific characteristic point of the reference guide mark.

Moreover, the calibration unit 60 acquires the coordinate values of the rotational center of the stage 10 in the first image capture coordinate system as a dummy first rotational center position, on the basis of the trajectory of the first reference guide mark included in the first images that are acquired from before the stage 10 is rotated, i.e. when it is in its set initial position, until after rotation has been completed.

In more concrete terms, the calibration unit 60 acquires, as first X-Y coordinate values, a plurality of X-Y coordinate values in the first image capture coordinate system of a plurality of first reference guide marks in a plurality of first images that are acquired each time a rotational shift of ΔΘ is performed. And the calibration unit 60 specifies a virtual circular arc on the basis of this plurality of first X-Y coordinate values according to the method of least squares. Then the calibration unit 60 acquires, as the dummy first rotational center position, the first X-Y coordinate values at the rotational center of the first image capture coordinate system on the basis of the first X-Y coordinate values corresponding to the center of this virtual circular arc that has been specified. In a similar manner, the calibration unit 60 can acquire, as a dummy second rotational center position, the second X-Y coordinate values at the rotational center of the second image capture coordinate system on the basis of a plurality of second images that are acquired each time a rotational shift of ΔΘ is performed.

Furthermore, as the dummy first rotational center position and the dummy second rotational center position, it would also be acceptable to arrange for the calibration unit 60 to acquire the X-Y coordinate values of the first image capture coordinate system and of the second image capture coordinate system at the rotational center, according to the following procedure.

The calibration unit 60 acquires a first image, which includes the first reference guide mark. And, as the first X-Y coordinate values before rotation, the calibration unit 60 acquires the X-Y coordinate values in the first image capture coordinate system of the first reference guide mark within the first image before rotation. Next, a command is issued to the shift mechanism control unit 80 to rotate the stage 10 through ΔΘ, within a range in which the first reference mark is included in the first image, in other words within a range within which the first reference guide mark is included within the first image capturing range of the first image capturing unit 40-1, and thereby the stage 10 is rotated. And, after the stage 10 has been rotated through ΔΘ, the calibration unit 60 acquires a first image, in which the first reference guide mark is included.

Next, as the first X-Y coordinate values after rotation, the calibration unit 60 acquires the X-Y coordinate values in the first image capture coordinate system of the first reference guide mark in the first image after rotation. And, after having acquired the first X-Y coordinate values before rotation by ΔΘ and after rotation by ΔΘ, the calibration unit 60 determines the isosceles triangle whose base is the straight line that connects between these first X-Y coordinate values before rotation by ΔΘ and after rotation by ΔΘ, and whose apical angle is ΔΘ corresponding to the amount of rotation of the stage 10 that was commanded to the shift mechanism control unit 80. Then the calibration unit 60 acquires the X-Y coordinate values in the first image capture coordinate system of the apex of this isosceles triangle that has been acquired (i.e. of its vertex where its apical angle is ΔΘ) as the dummy first rotational center position at the rotational center of the first image capture coordinate system. In a similar manner, it may be arranged for the calibration unit 60 to acquire the X-Y coordinate values of the second reference mark within the second image before rotation through ΔΘ and the X-Y coordinate values of the second reference mark within the second image after rotation through ΔΘ, as the second X-Y coordinate values before rotation and the second X-Y coordinate values after rotation. Furthermore, it may be arranged for the calibration unit 60 to determine the isosceles triangle whose base is the straight line that connects between these second X-Y coordinate values before rotation by ΔΘ and after rotation by ΔΘ and whose apical angle is ΔΘ, and then to acquire the X-Y coordinate values in the second image capture coordinate system of the apex of this isosceles triangle (where its apical angle is ΔΘ) as the dummy second rotational center position at the rotational center of the second image capture coordinate system.

Next, on the basis of the first image capture coordinate system correspondence relationship and the dummy first rotational center position, the calibration unit 60 designates an arbitrary first point that is included in the first image capturing range of the first image capturing unit 40-1, and commands the shift mechanism control unit 80 to rotate the stage 10 around this first point as center (step SI 02).

In more concrete terms, the calibration unit 60 selects any arbitrary X-Y coordinate values in the first image capture coordinate system that are included within the first image capturing range, as the first X-Y coordinate values of the first point. Next, the calibration unit 60 acquires the differential coordinate values between the first X-Y coordinate values that have been selected and the first X-Y coordinate values of the dummy first rotational center position. And, from the first X-Y coordinate values of the dummy rotational center position, the calibration unit 60 commands the shift mechanism control unit 80 to rotate the stage 10, so as to make the position that is shifted by just the differential X-Y coordinate values that have been acquired become the rotational center position.

Next, on the basis of the first reference guide marks included in the first images before and after rotation with the first point being taken as center, the calibration unit 60 acquires the X-Y coordinate values of the first point in the first image capture coordinate system as the first rotational center position (step SI 04). It would also be acceptable to arrange for the calibration unit 60 to acquire the first rotational center position according to a virtual circular arc based upon the method of least squares, as described above. Moreover, it would also be possible to arrange for the calibration unit 60 to acquire the first rotational center position according to an isosceles triangle that takes the first reference guide marks before and after rotation for its base.

Then, as the second rotational center position, the calibration unit acquires the X-Y coordinate values of the first point in the second image capture coordinate system on the basis of the second reference guide marks included in the second images before and after rotation, with the first point being taken as the center (step SI 06).

Next, the calibration unit 60 stores the first rotational center position and the second rotational center position specified in the steps SI 04 and SI 06 in the coordinate system correspondence relationship storage unit 66 in mutual correspondence as a coordinate system correspondence relationship (step SI 08).

Furthermore, the calibration unit 60 then makes a decision as to whether or not it has been possible to acquire a standard number that has been determined in advance of these coordinate system correspondence relationships in which a first rotational center position and a second rotational center position correspond together (step SI 10). It should be understood that it would be acceptable for this standard number to be two or more, provided that the first image capturing unit 40-1 and the second image capturing unit 40-2 are provided with accurate orthogonal coordinate systems for the first image capture coordinate system and the second image capture coordinate system. Moreover, if for example due to the influence of lens distortion or the like the first image capturing unit 40-1 and the second image capturing unit 40-2 do not have accurate orthogonal coordinate systems, then this standard number should be three or more.

It should be understood that in the above description an example has been explained in which, when rotations have been performed around any arbitrary plurality of first points within the first image capturing range as centers, coordinate system correspondence relationships are acquired that specify the correspondence relationships between the first image capture coordinate system and the second image capture coordinate system

corresponding to those first points. However, if rotations are performed around any arbitrary plurality of second points within the second image capturing range as centers, then it would also be acceptable further to acquire a coordinate system correspondence relationship specifying the correspondence relationships between the first image capture coordinate system and the second image capture coordinate system corresponding to those second points. By acquiring the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system when each of a point within the first image capturing range and a point within the second image capturing range is rotated to the center in this manner, it is possible to acquire a coordinate system correspondence

relationship that gives the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system in a more accurate manner.

In this embodiment, the alignment unit 70 shifts the object 20 to its target position by utilizing the coordinate system correspondence relationship described above that specifies the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system.

Fig. 5 shows an example of a procedure for performing alignment in order for the alignment unit 70 to shift the object 20 to its target position. It should be understood that the target first X-Y coordinate values of the first guide mark in the first image capture coordinate system and the target second X-Y coordinate values of the second guide mark in the second image capture coordinate system that correspond to the target position of the object 20 are stored by the shift mechanism control device 50 in advance. For example, the object 20 may be mounted in advance accurately in its target position upon the stage 10, and, on the basis of a first image and a second image that are captured in this state, the shift mechanism control device 50 may acquire in advance and store target first X-Y coordinate values of the first guide mark in the first image capture coordinate system and target second X-Y coordinate values of the second guide mark in the second image capture coordinate system.

When alignment is to be performed, first the object 20 is installed upon the stage 10. Next, the alignment unit 70 acquires a first image captured by the first imaging unit 40-1, including the first guide mark that is determined in advance with respect to the object 20, in other words with respect to the corner portion 20a. And on the basis of this first image the alignment unit 70 specifies, as being the first position, the X-Y coordinate values of the vertex 20b of the corner portion 20a in the first image capture coordinate system (step S200). Then the alignment unit acquires a second image captured by the second image capturing unit 40-2, including the second guide mark that is determined in advance with respect to the object 20, in other words, the corner portion 20c. And, on the basis of this second image, the alignment unit 70 specifies the X-Y coordinate values of the vertex 20d of the corner portion 20c in the second image capture coordinate system (step S202). And then, by referring to the coordinate system correspondence relationship that specifies the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system, the alignment unit 70 specifies, as being the second position, the X-Y coordinate values in the first image capture coordinate system that correspond to these specified X-Y coordinate values in the second coordinate system (step S204).

Next, the alignment unit 70 acquires the differentials between the target first X-Y coordinate values acquired in advance and the X-Y coordinate values corresponding to the first position specified in the step S200, and specifies these differentials as being the parallel shift amounts for the stage 10 (step S206).

And then the alignment unit 70 acquires the angle subtended by the straight line that connects together the first position specified in the step S200 and the second position specified in the step S204, and the target line that connects together the target first X-Y coordinate values and the X-Y coordinate values in the first image capture coordinate system that correspond to the target second X-Y coordinate values (step S208). And the alignment unit 70 specifies this angle that it has acquired as being the rotation amount for the stage (step S210).

After having specified the parallel shift amounts and the rotation amount, the alignment unit 70 first issues a command to the shift mechanism control unit 80 to shift the stage 10 by just the parallel shift amounts in the X direction and in the Y direction. After this shifting, the alignment unit 70 issues a command to the shift mechanism control unit 80 to rotate the stage 10 by just the specified rotation amount in the Θ direction around the first guide mark as center, in other words around the target first X-Y coordinate values as center. By the above, the alignment unit 70 is able to shift the stage 10 to the target position.

It should be understood that in the above description an example has been explained in which, after having parallel shifted the stage 10, the alignment unit 70 shifts the stage 10 to its target position by rotating the target first X-Y coordinate values to the center. However, it would also be acceptable to make the alignment unit 70 shift the stage 10 to its target position in the following manner.

That is, the alignment unit 70 acquires, as the rotation amount, the angle subtended by the straight line that connects between the first position specified in the step S200 and the second position specified in the step S204, and the target line that connects between the X-Y coordinate values in the first image capture coordinate system corresponding to the target first X-Y coordinate values and the target second X-Y coordinate values. Next, the alignment unit 70 acquires the X-Y coordinate values of the first guide mark in the first image capture coordinate system and the X-Y coordinate values of the second guide mark in the first image capture coordinate system, when shifting has been performed by just this rotation amount that has been acquired while taking the arbitrary point within the first image capturing range as center. And the alignment unit 70 acquires the differential X-Y coordinate values between the X-Y coordinate values of the first guide mark in the first image capture coordinate system that have been acquired and the target first X-Y coordinate values. Moreover, the alignment unit 70 acquires the differential X-Y coordinate values between the X-Y coordinate values of the second guide mark in the first image capture coordinate system that have been acquired and the X-Y coordinate values in the first image capture coordinate system that correspond to the target second X-Y coordinate values. Then the alignment unit 70 specifies the parallel shift amounts in the X direction and in the Y direction in order to shift the stage 10 to its target position, by taking the average values of each of these differential X-Y coordinate values that have been acquired. And next the alignment unit 70 shifts the stage 10 by just the rotation amount that has been acquired. And, after rotation, the alignment unit 70 shifts the object 20 to its target position by further parallel shifting the stage 10 by just the parallel shift amount that has been specified.

Moreover, in the above description, an example has been explained in which, by referring to the coordinate system correspondence relationship, the alignment unit 70 specifies the parallel shift amount and the rotation amount for shifting the object 20 to its target position by converting X-Y coordinate values in the second image capture coordinate system to X-Y coordinate values in the first image capture coordinate system. However, it would also be acceptable to arrange for the alignment unit 70 to specify the parallel shift amount and the rotation amount for shifting the object 20 to its target position by referring to the coordinate system correspondence relationship, and by converting X-Y coordinate values in the first image capture coordinate system to X-Y coordinate values in the second image capture coordinate system.

As described above, by the method of rotating the stage 10 about an arbitrary point within the image capturing range of the image capturing unit as center, it is possible to specify with good accuracy a coordinate system correspondence relationship that specifies the correspondence relationship between the stage coordinate system, the first image capture coordinate system, and the second image capture coordinate system. However, if higher accuracy is demanded, then it is possible further to perform the processing described below, with the objective of enhancing the pitch accuracy between the plurality of image capturing units.

After calibration by the method described above has been completed with a certain level of accuracy, when the mobile object is shifted parallel to itself, the calibration unit 60 calculates actually measured values in the image capture coordinate systems of the shift distances of reference marks that are determined in advance on the mobile object, and then calculates a correlation coefficient on the basis of the ratios of the calculated actually measured values. Furthermore, on the basis of this correlation coefficient, the calibration unit 60 specifies the parallel shift amounts in the X direction and in the Y direction for the stage 10, in order to shift the object 20 to its target position. Here, it is presumed that the correspondence relationship between the distances in the stage coordinate system (for example expressed in units of millimeters) and the distances in the image capture coordinate systems (expressed in units of pixels) is ascertained in advance with at least a fixed accuracy; and by the actually measured values of shift distance is meant the reference guide mark shift amounts that are actually measured in the image capture coordinate systems.

In concrete terms, the calibration unit 60 commands the shift mechanism control unit 80 to shift the stage 10 parallel to itself by just a distance determined in advance in one direction (for example the X direction of the stage coordinate system), within the range in which, both before and after shifting, the first reference guide mark is received within the first image that is captured by the first image capturing unit 40-1 and moreover the second reference guide mark is received within the second image that is captured by the second image capturing unit 40-2. And, when the stage 10 is shifted parallel to itself by just this distance that is determined in advance, the calibration unit 60 specifies a correction coefficient on the basis of the ratio between the actually measured value of the shift distance of the first reference guide mark as specified on the basis of the first image, and the actually measured value of the shift distance of the second reference guide mark as specified on the basis of the second image. Here, the calibration unit 60 takes the actually measured value of the shift distance of the first reference guide mark in the first image capture coordinate system as a standard actually measured distance, and specifies the coefficient by normalizing the actually measured value of the shift distance of the second reference guide mark in the second image capture coordinate system with respect to this standard actually measured distance.

For example, if the shift of the stage 10 in the X direction in the stage coordinate system is 1.000 mm, and the actually measured value of this shift distance in the first image capture coordinate system is 1.000 mm, while due to some cause or other the actually measured value of this shift distance in the second image capture coordinate system is 1.001 mm, then the alignment unit 70 takes the correction coefficient related to the second image capture coordinate system to be 1.001 (1.001/1.000), and substitutes a value resulting from dividing the parallel shift amount by this coefficient as the parallel shift amount after amendment related to the second image capture coordinate system. With this processing, it is possible to reduce the measurement errors calculated by each of a plurality of image capture coordinate systems.

If, as described above, the pitch accuracy is enhanced between the plurality of image capturing units, then it is sufficient to perform the measurement of the shift distance at least once (the number of times image capture is performed is twice by each image capturing unit, i.e. before and after the parallel shifting). However, it would also be acceptable to arrange for the calibration unit 60 to change the start point and the end point of parallel shifting, to measure the actually measured value of the shift distance twice or more, and to specify the correction coefficient on the basis of the average of all these actually measured values.

It should be understood that while, in the explanation described above, the first reference guide mark and the second reference guide mark upon the stage 10 were used, it would also be acceptable to use a first guide mark and a second guide mark that were determined in advance upon the object disposed upon the stage 10, as the first reference guide mark and the second reference guide mark.

As described above, according to this embodiment, a coordinate system

correspondence relationship that specifies the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system is acquired in advance in an accurate manner by the calibration process. Accordingly, for example, with a mobile object control system that controls a mobile object on the basis of images captured by a plurality of image capturing units, it is possible to prevent the shifting of the object to its target position from taking a long period of time because the accuracy of the correspondence relationship between the respective image capture coordinate systems determined for each of the image capturing units is poor. For example, in the prior art, in order to ensure high accuracy for the correspondence relationship between the various image capturing units, it was necessary to install each of the image capturing units accurately in a position that was determined in advance. However, according to this embodiment, after having installed the various image capturing units, it is possible to acquire the correspondence relationship between the various image capturing units with good accuracy on the basis of images that are captured by those image capturing units. Accordingly, it is possible to install the various image capturing units in positions that are not accurately determined in advance. Moreover, even if the position of installation of some one of the image capturing units should shift away from its intended position, it is still possible to acquire the correspondence relationship between the various image capturing units over again with good accuracy by performing the calibration described above again.

Furthermore, for example, the radius of a circular arc that is drawn on the basis of the trajectory of the first reference guide mark due to rotation around a point within the first image capturing range as center is smaller than the radius of a circular arc that is drawn on the basis of the trajectory of the first reference guide mark due to rotation around a point outside the first image capturing range as center. Accordingly, the error is smaller for a first rotational center position that is specified on the basis of a circular arc drawn by rotation about a point within the first image capturing range, than for a first rotational center position that is specified on the basis of a circular arc drawn by rotation about a point outside the first image capturing range. In a similar manner, if the stage 10 is rotated around a point within the first image capturing range as center, then the length of each of the two equal sides of the isosceles triangle that is acquired is comparatively short, and the angle at its apex is comparatively large. On the other hand, if the stage 10 is rotated around a point outside the first image capturing range as center, then the length of each of the two equal sides of the isosceles triangle that is acquired is comparatively great, and the angle at its apex is comparatively small. Accordingly, the possibility is high that the error included in the first rotational center position that is acquired on the basis of an isosceles triangle is smaller in the case of rotation about a point within the first image capturing range as center, than in the case of rotation about a point outside the first image capturing range as center.

Thus if, as described above, for example, the stage 10 is shifted to its target position by rotating the stage 10 around a point within the first image capturing range as center, then the first X-Y coordinate values of this rotational center in the first image capture coordinate system will be specified comparatively accurately. Accordingly, the parallel shift amount and the rotation amount for the stage 10 that are required in order to shift the object 20 to its target position can be specified comparatively accurately. Thus, it is possible to prevent the shifting of the object to its target position from taking a long period of time.

Furthermore, in the prior art, the correspondence relationship between the first image capture coordinate system and the stage coordinate system and the correspondence relationship between the second image capture coordinate system and the stage coordinate system were maintained individually and separately. However, if errors are included in the correspondence relationship between the first image capture coordinate system and the stage coordinate system and also in the correspondence relationship between the second image capture coordinate system and the stage coordinate system, then a larger error will be included in the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system, which is acquired via the stage coordinate system. Accordingly, if the alignment unit 70 shifts the object 20 to its target position on the basis of a correspondence relationship between the first image capture coordinate system and the second image capture coordinate system that is acquired via the stage coordinate system, then a long period of time is required for shifting the object 20 to its target position.

On the other hand, in this embodiment, the calibration unit 60 acquires the coordinate system correspondence relationship that specifies the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system corresponding to each of a plurality of first points within the first image capturing range, when the stage 10 is rotated around each of this plurality of first points as center. In other words, the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system is not acquired via the stage coordinate system. Thus, according to this embodiment, it is possible to shorten the time period taken for shifting the object 20 to its target position, as compared to the case when the stage 10 is controlled on the basis of a correspondence relationship between the first image capture coordinate system and the second image capture coordinate system that is acquired via the stage coordinate system. In the embodiment described above, a method was explained of enhancing the calibration accuracy in relation to an arbitrary point within the image capturing range.

However, according to only this method, in relation to an arbitrary point specified on the basis of the image capture coordinate system that is outside the image capturing range, no consideration is accorded to the correspondence relation between the image capture coordinate system and the stage coordinate system. However, in the following explanation, unless specifically stated otherwise, a system structure is assumed that employs a single image capturing unit, and a calibration method (sometimes termed "spatial calibration") will be described that takes as its objective to ascertain with good accuracy the correspondence relationship between the image capture coordinate system and the stage coordinate system at an arbitrary point that is not limited to being within the image capturing range.

Fig. 6 shows the functional blocks of a mobile object control system according to another embodiment. The feature of difference between the functional blocks shown in Fig. 6 and those of the mobile object control system shown in Fig. 3 is that the calibration unit 60 includes a designated coordinate values specification unit 65 and a correspondence relationship correction unit 67. As designated coordinate values that specify the rotational center position when rotating the stage 10, the designated coordinate values specification unit 65 specifies coordinate values in any arbitrary first image capture coordinate system, either within the image capturing range of the first image capturing unit 40-1 or outside its image capturing range. And, by rotating the stage 10 around a center positioned to correspond to these designated coordinate values, according to a procedure which will be described hereinafter, the correspondence relationship correction unit 67 corrects the coordinate system correspondence relationship that specifies the correspondence relationship between the stage coordinate system and the first image capture coordinate system.

The calibration unit 60 acquires in advance a coordinate system correspondence relationship between the first image capture coordinate system and the stage coordinate system, according to the procedure explained in connection with the step SI 00 of Fig. 4. And, at the start of spatial calibration processing, the calibration unit 60 puts the stage 10 into a first attitude. When the stage 10 is in this first attitude, the first reference mark is located within the first image.

Next, with the designated coordinate values specification unit 65, the calibration unit 60 specifies an arbitrary point by designated coordinate values (Px, Py) in the first image capture coordinate system, this point not being limited to lying within the first image capturing range of the first image capturing unit 40-1. And the calibration unit 60 refers to the coordinate system correspondence relationship, and specifies the coordinate values (Px, Py) in the stage coordinate system that correspond to these designated coordinate values (Px, Py). Then, taking the specified coordinate values (px, py) as center, the calibration unit 60 commands the shift mechanism control unit 80 to rotationally shift the stage 10 through an arbitrary rotational angle, within the range in which the first reference guide mark lies within the first image both before and after rotational shifting. By doing this, the attitude of the stage 10 after rotational shifting becomes a second attitude.

The calibration unit 60 then specifies the position of the first reference guide mark in the first attitude and in the second attitude as coordinate values in the first image capture coordinate system. Moreover, the calibration unit 60 acquires the rotational center position calculated on the basis of these coordinate values and the above described rotational angle as coordinate values (Qx, Qy) in the first image capture coordinate system. Or it would also be acceptable to arrange for the calibration unit 60 to put the stage 10 into three or more attitudes by similar rotational shifts, to specify a virtual circular arc based upon the three or more sets of coordinate values of the first reference guide mark in the first images on the basis of the method of least squares, and to acquire the coordinate values that correspond to the center of this virtual arc that has been specified as the coordinate values (Qx, Qy).

If perfect calibration is implemented both within the image capturing range and outside the image capturing range, then the coordinate values (Px, Py) and the coordinate values (Qx, Qy) will agree with one another. However, normally it is the case that they do not agree with one another. Thus, the calibration unit 60 specifies coordinate values (Rx, Ry) corrected on the basis of the coordinate values (Px, Py) and the coordinate values (Qx, Qy) as designated coordinate values after amendment. In this embodiment, it is supposed that the reliability of the coordinate values (Qx, Qy) is high, so that the calibration unit 60 takes the coordinate values (Qx, Qy) as the designated coordinate values after amendment (Rx, Ry), just as they are. And next, with the correspondence relationship correction unit 67, the calibration unit 60 corrects the coordinate system correspondence relationship by establishing correspondence between the specified coordinate values (Px, Py) and the designated coordinate values after amendment (Rx, Ry). Alternatively, it would also be acceptable to arrange for the calibration unit 60 to specify the designated coordinate values after amendment by assigning any appropriate weights to the coordinate values (Px, Py) and the coordinate values (Qx, Qy), or by taking the average values of the weighted coordinate values (Px, Py) and the coordinate values (Qx, Qy).

Furthermore, as another alternative, it would also be acceptable, if the shift mechanism control unit 80 is commanded to rotationally shift the stage 10 through an arbitrary rotational angle, to arrange for the calibration unit 60 to acquire the coordinate values of the first reference guide mark in a plurality of attitudes, without the first reference guide mark being limited to lying within the first image both before and after the rotational shifting. However, since it becomes impossible for an image of the reference guide mark to be captured by the image capturing unit if the first reference guide mark shifts to outside the image capturing range, accordingly the calibration unit 60 shifts the stage 10 parallel to itself after having rotationally shifted it, so that the first reference guide mark is received within the image capturing range.

The concrete procedure is as follows. First, the calibration unit 60 specifies the designated coordinate values (Px, Py) before correction. And the calibration unit 60 focuses its attention upon the coordinate values (Mix, Mly) of the first reference guide mark in the image capture coordinate system that are present within the image capturing range, and rotationally shifts the stage 1 through an arbitrary rotational angle centered upon the designated coordinate values (Px, Py) before correction. In this case, there is a possibility that the first reference guide mark may temporarily shift to outside the image capturing range. Next, on the basis of the designated coordinate values (Px, Py) before correction and the above described arbitrary rotational angle, the calibration unit 60 specifies the position to which, according to calculation, the first reference guide mark will shift as the coordinate values (M2x, M2y). And, having calculated the coordinate values (Mix, Mly) and the coordinate values (M2x, M2y) in the X and Y directions, the calibration unit 60 calculates their differential values (M2x-Mlx, M2y-Mly). Next, the calibration unit 60 shifts the stage 10 parallel to itself by just an amount that corresponds to these differential values (M2x-Mlx, M2y-Mly), so as to bring the first reference guide mark close to its proper position. It will be clear to a person skilled in the art that it is possible actually to execute the above described rotational shifting and parallel shifting as a single combined movement. Now, if perfect calibration within the image capturing range is implemented, then the coordinate values (M3x, M3y) of the first reference guide mark in the first image capture coordinate system after the parallel shifting specified from the first images and the coordinate values (Mix, Mly) will agree with one another. However, normally a disagreement is present. The possibility is high that the cause of this disagreement originates in the fact that the accuracy of determination of the designated coordinate values (Px, Py) before correction is not sufficient. In other words, the possibility is high that the amount of deviation of the coordinate values (M3x, M3y) with respect to the coordinate values (Mix, Mly) represents an amount of deviation with respect to the designated coordinate values (Px, Py) of coordinate values that are closer to the true rotational center position. Thus, the calibration unit 60 acquires the position of the first reference guide mark when the stage 10 is in its attitude after rotation and moreover before parallel shifting as the coordinate values (M4x, M4y), by adding the calculated differential values for the X and Y directions calculated as described above to the coordinate values (M2x, M2y).

The coordinate values (Mix, Mly) and the coordinate values (M4x, M4y) that have been obtained in this way can be replaced for the "position of the first reference guide mark in the first attitude and in the second attitude" in the previous explanation related to

acquisition of the rotational center position in the first image capture coordinate system as the coordinate values (Qx, Qy). By a similar procedure, it is possible to acquire the position of the first reference guide mark corresponding to a plurality of rotational shifts. It should be understood that the subsequent procedure for specifying the designated coordinate values after amendment (Rx, Ry) is as already described.

Here, the step of parallel shifting the stage 10 so as to bring the first reference guide mark close to its proper position is performed with the objectives of making the rotational angle comparatively large, keeping the first reference guide mark within the image capturing range, and moreover specifying the designated coordinate values after amendment (Rx, Ry) on the basis of the virtual circular arc specified by the shifting trajectory of the first reference guide mark. Accordingly, it would also be acceptable to determine the parallel shift amount on the basis of the image capturing range, and not on the basis of the differential values (M2x-Mlx, M2y-Mly) as in the case of the example described above. Moreover, the calibration method that includes this parallel shifting described above is one in which the designation accuracy is enhanced when the arbitrary point is designated by the image processing device via the image capturing unit. Accordingly, it is possible to implement the various types of calibration method described in this specification in combination, or partially replaced, or individually; and all these types of embodiment are considered to be embraced within the overall concept of the invention of the present application.

In a similar manner, with the designated coordinate values specification unit 65, the calibration unit 60 specifies a plurality of designated coordinate values respectively

corresponding to linear coordinate values arranged upon a straight line that is determined in advance in the image capture coordinate system, for example corresponding to each of a set of lattice points that are determined in advance, and thus specifies a designated coordinate value after amendment for each of the designated coordinate values. Moreover, the

calibration unit 60 further corrects the designated coordinate values after amendment that have been specified so as to make them correspond to linear coordinate values. In other words, the calibration unit 60 further corrects the designated coordinate values after amendment, in such a way that the designated coordinate values after amendment are arranged upon a straight line that is determined in advance. And the calibration unit 60 corrects the coordinate system correspondence relationship so as to ensure that there is proper correspondence between the designated coordinate values after amendment that have been corrected and the coordinate values in the stage coordinate system. By doing this, it is possible to enhance the accuracy of spatial determination over a broad range that is not necessarily limited to the image capturing range.

The distribution range and the number of the designated coordinate values after amendment specified by this execution of spatial calibration may be determined as desired, according to the actual application. However, the broader is the range and the greater is the number of measurements are performed, the more is it possible to anticipate enhancement of the spatial determination accuracy, and the better is the accuracy at which it becomes possible to interpolate at points where measurement has not been performed. If the array of the points having corrected designated coordinate values is not linear, then it is possible to correct this distortion to linear by using a mathematical model for conversion with a polynomial equation. The number of coefficients of this polynomial equation conversion is given by (n+1) x (n+2). Thus, if a cubic polynomial equation is designated, then the number of coefficients that define the conversion becomes 20. In this case, twenty or more designated coordinate values after amendment should be acquired. It would also be acceptable to arrange for the calibration unit 60 to correct the coordinate system correspondence relationship by establishing correspondence between twenty or more designated coordinate values after amendment in which the array of points has been corrected linearly, and the coordinate values in the stage coordinate system.

To cite one of the merits of enhancing the calibration accuracy outside the image capturing range: during alignment, it is possible to forecast the attitude of the stage 10 after rotational shifting with high accuracy even when some arbitrary position that is outside the image capturing range has been specified as the rotational center. To cite another of the merits: it is possible accurately to specify the position of a body that lies outside the image capturing range on the basis of information that is included within the image capturing range. For example, if a portion of an object can be seen within the image capturing range, then it is possible to perform measurement for another portion whose positional relationship relative to that portion is already known, at whatever position outside the image capturing range it may be located. Due to the fact that it is possible, so to speak, to "see into places that cannot be seen", there is a possibility that, even although the number of working processes that are automated for a single object is increased, it is still possible to keep down the number of image capturing units that are required.

Furthermore, with a system that uses a so called UVW stage control mechanism or some mechanism of a similar type, there are constraints that originate in mechanical shift limits. However, with a shift mechanism that is provided with a plurality of ball screws and motors for shifting an object from its position of installation to its target position, the number of combinations of shift amounts for the various drive units can be rather large. With this type of system, it is possible to select the rotational center strategically according to an appropriate standard. For example it becomes possible, each time the object is replaced, to shift the object along a shift path that corresponds to a combination of shift amounts, in order to minimize the cumulative amount of wear upon the drive portions of the shift mechanism, or in order to spread the load. The accuracy of control is maintained in this case as well. Moreover the accuracy of control is maintained, even if the stage 10 is not returned to its base attitude each time the object is replaced during production processing.

Furthermore, if a system structure is employed that uses two image capturing units, then, by referring to the coordinate system correspondence relationship that specifies the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system, it is possible to specify, not only the position of the first reference guide mark that is included in the first image and the position of the second reference guide mark that is included in the second image, but also the coordinate values (Px, Py), the coordinate values (Qx, Qy), and the coordinate values (Rx, Ry), as X-Y coordinate values in one of the image capture coordinate systems. In concrete terms, in the step of acquiring the coordinate values (Qx, Qy) described above, the calibration unit 60 can calculate the rotational center position (Qlx, Qly) on the basis of the shift trajectory of the first reference guide mark and the rotational center position (Q2x, Q2y) on the basis of the shift trajectory of the second reference guide mark, and can specify the coordinate values (Qx, Qy) on the basis of these coordinate values. For example, the average values of the

coordinate values (Qlx, Qly) and the coordinate values (Q2x, Q2y) may be taken as the coordinate values (Qx, Qy).

Moreover, in the step of specifying an arbitrary point that is not limited to lying within the image capturing range by the designated coordinate values (Px, Py) before correction, it would also be acceptable to arrange to specify, as the designated coordinate values (Px, Py) before correction, any arbitrary point upon the line that is the perpendicular bisector of the straight line connecting an arbitrary point that is specified on the basis of the first reference guide mark included in the first image and an arbitrary point specified on the basis of the second reference guide mark that is included in the second image. By doing this, it is possible to utilize both of the two image capturing ranges, and thus to specify the coordinate values (Qx, Qy) with higher accuracy. With regard to the accuracy of the calculation of the rotational center that is founded upon the radius of the circular arc and the rotation angle, this is as explained above. Furthermore it would also be acceptable to arrange, by shifting the stage 10 with respect to the image capturing units, to shift the first reference guide mark and the second reference guide mark to different positions and to repeat similar processing. By doing this, it would be possible to obtain a large number of arbitrary points upon the perpendicular bisector line mentioned above. In other words, by utilizing the two image capturing ranges, it would be possible to specify a large number of designated coordinate values after amendment.

In the prior art technique, the focus has been upon enhancing the accuracy of measurement of the specified rotational center point (which generally is the control center when the stage is in its base attitude, and, in the case of a so called X-Υ-θ stage control mechanism, is the point of intersection of the X axis and the Y axis). On the other hand, in this embodiment, the image processing device that processes the images captured by the image capturing units actively provides a control position via the image capturing units, and the mobile object is freely controlled on the basis of this control position. In other words, in this embodiment, the intention is to endow the control strategy with flexibility.

According to the above, it becomes possible to control the stage 10 with good accuracy by specifying the designated coordinate values after amendment. However, the correspondence relationship between the rotational angle commanded for the stage 10 and the actual rotational angle is not yet verified. Due to this there is a possibility that, even though the stage 10 may have been rotated around a control position that corresponds accurately to the coordinate values, still some disparity may arise between the rotational angle in the image capture coordinate system and the actual rotation shift angle of the stage 10. This type of disparity would constitute an obstacle to the final objective of a system to which it is anticipated that this embodiment will be applied, which is to shift the object to an arbitrary position. Accordingly, in the following, a calibration method (sometimes called "rotational angle calibration") will be described that takes as its objective to enable accurate rotational shifting according to a specified rotational angle.

For starting this rotational angle calibration, first, the calibration unit 60 commands the shift mechanism control unit 80 to shift the stage 10 to its set initial position. After the stage 10 has been shifted to its set initial position, the calibration unit 60 repeatedly shifts the stage 10 by an arbitrary angle in the Θ direction, and, each time, acquires the X-Y coordinate values in the image capture coordinate system of a reference guide mark that is included in the image. And, as a rotational angle correspondence relationship, the calibration unit 60 stores, in the rotational angle correspondence relationship storage unit 69, the X-Y coordinate values of the stage with respect to the set initial position in the stage coordinate system and in the image capture coordinate system, and the rotational angle in the stage coordinate system and the rotational angle in the image capture coordinate system, that have been acquired each time, in mutual correspondence. The rotational angle in the stage coordinate system is the rotational angle that is recognized by the shift mechanism control unit 80. And the rotational angle in the image capture coordinate system may be calculated on the basis of trigonometric function theory from the coordinate values of the rotational center point for each rotational shift and the two vertices at the bottom corners of the isosceles triangle described virtually by the reference guide mark before and after shifting. It should be understood that there is no need for the arbitrary rotational angles of the rotational shifts to be equal to one another. And it should be understood that the alignment unit 70 specifies the rotational angle of the stage 10 for shifting the stage 10 to its target position by referring to the rotational angle

correspondence relationship. In other words, the alignment unit 70 specifies the rotational angle in the stage coordinate system corresponding to the rotational angle that was specified in the image capture coordinate system by referring to the rotational angle correspondence relationship.

The greater is the number of measurement points resulting from variation of the rotational center position and the rotational angle, the better is the accuracy of the rotational angle correspondence relationship enhanced. Angles that are not measured may be

interpolated by any desired method. It should be understood that, if angular calibration is performed while choosing the rotational angle to be large with respect to the image capturing range, then it is possible to avoid any constraining condition based upon the image capturing range by combining rotational shifting and parallel shifting according to the same method as previously described with reference to the processing for keeping the reference guide mark within the image capturing range.

It should be understood that primarily, in this embodiment, a calibration method for the image capture coordinate systems of two image capturing devices is disclosed. However, it would also be acceptable to arrange to calibrate the image capture coordinate systems of three or more image capturing devices mutually and moreover on a multiple basis. For example, if three image capturing devices A, B, and C are employed, then, by applying the structure of this embodiment between the image capturing devices A and B, between B and C, and between A and C, it is possible to enhance the accuracy of the entire system to a higher level than in the case when the present invention is applied only between A and B and between B and C. Furthermore, by combining a plurality of image capturing devices that are generally sold at a comparatively cheap price, and by performing mutual and multiple calibration of this type, it is possible to handle a very wide range working region of an extent that could not be dealt with by any prior art technique, just as though image capturing over that region was being performed by a single huge image capturing device.

It should be understood that it would also be acceptable to construct the shift mechanism control device 50 according to this embodiment by installing a program that performs the various processes described above related to calibration and to alignment upon a computer, and by executing this program. In other words, it would also be acceptable to arrange to construct the shift mechanism control device 50 by causing a computer to function as the first image acquisition unit 42-1, the second image acquisition unit 42-2, the calibration unit 60, the coordinate system correspondence relationship storage unit 66, the alignment unit 70, the target position storage unit 78, and the shift mechanism control unit 80, by a program that performs various types of processing related to calibration and alignment being executed by this computer.

This computer includes a CPU and memory of various types such as ROM, RAM, EEPROM (registered trademark) and so on and a communication bus and interfaces, and functions as the shift mechanism control device 50 by a processing program that is stored in advance in the ROM as firmware being read out by the CPU and sequentially executed.

While the present invention has been explained with the use of embodiments, the technical scope of the present invention is not limited by the range of the embodiments described above. It will be clear to a person skilled in the art that it is possible to implement various changes or improvements to the embodiments described above. From the scope of the Claims, it will be clear that it is possible for changes or improvements of this type also to be included within the technical scope of the present invention.

The sequence of execution of processing of the operations, orders, steps, stages and so on for the devices, systems, programs, and methods described in the Claims, the

specification, and the drawings is not explicitly laid down as being particularly "before", "after", and so on, and moreover, it must be accepted that they may be implemented in any desired order, unless the output of previous processing is used in subsequent processing.

Although, in relation to the operational flow, the explanation in the Claims, the specification, and the drawings has for the sake of convenience employed the terms "first", "next" and so on, it should be understood that the implementation of this sequential order is not to be

considered as being essential to the present invention.

EXPLANATION OF THE REFERENCE SYMBOLS

10: stage

20: object

30: shift mechanism

32: first X direction shift mechanism

34: second X direction shift mechanism 36: Y direction shift mechanism

40-1 : first image capturing unit

40-2: second image capturing unit

42-1 : first image acquisition unit

42-2 second image acquisition unit

50: shift mechanism control device

60: calibration unit

66: coordinate system correspondence relationship storag

70: alignment unit

72: position specification unit

74: parallel shift amount specification unit

76: rotation amount specification unit

78: target position storage unit

80: shift mechanism control unit

100: mobile object control system

Claims

CLAIMS 1. A mobile object control system, comprising:

a first image acquisition unit that, when a mobile object is rotated around an arbitrary first point as center that is within a first image capturing range of a first image capturing unit that captures first images including a first reference guide mark provided in advance upon the mobile object, acquires the first images captured by the first image capturing unit before rotation and after rotation;

a second image acquisition unit that, when the mobile object is rotated around the first point as center, acquires second images captured by a second image capturing unit that captures second images including a second reference guide mark provided in advance upon the mobile object before and after rotation;

a first rotational center position specification unit that, on the basis of the first reference guide marks included in each of the first images, specifies a first rotational center position corresponding to the first point in a first image capture coordinate system that is determined in advance with respect to the first image capturing unit;

a second rotational center position specification unit that, on the basis of the second reference guide marks included in each of the second images, specifies a second rotational center position corresponding to the first point in a second image capture coordinate system that is determined in advance with respect to the second image capturing unit; and

a coordinate system correspondence relationship storage unit that, on the basis of the first rotational center position and the second rotational center position, maintains a coordinate system correspondence relationship that specifies a correspondence relationship between the first image capture coordinate system and the second image capture coordinate system.

2. The mobile object control system according to Claim 1, wherein:

the first image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of first points within the first image capturing range as center, acquires the first images captured by the first image capturing unit both before rotation and after rotation; the second image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of first points within the first image capturing range as center, acquires the second images captured by the second image capturing unit both before rotation and after rotation;

the first rotational center position specification unit specifies each of the first rotational center positions corresponding to each of the first points on the basis of the first reference guide marks included in each of the first images before rotation and after rotation; the second rotational center position specification unit specifies each of the second rotational center positions corresponding to each of the first points on the basis of the second reference guide marks included in each of the second images before rotation and after rotation; and

the coordinate system correspondence relationship storage unit maintains the coordinate system correspondence relationship on the basis of each of the first rotational center position and the second rotational center position.

3. The mobile object control system according to Claim 1 or Claim 2, wherein:

when the mobile object is rotated around any arbitrary second point within the second image capturing range of the second image capturing unit as center, the first image acquisition unit acquires the first images captured by the first image capturing unit before and after rotation;

when the mobile object is rotated around the second point as center, the second image acquisition unit acquires the second images captured by the second image capturing unit before and after rotation;

the first rotational center position specification unit specifies the first rotational center position corresponding to the second point in the first image capture coordinate system on the basis of the first reference guide marks included in each of the first images before and after rotation;

the second rotational center position specification unit specifies the second rotational center position corresponding to the second point in the second image capture coordinate system on the basis of the second reference guide marks included in each of the second images before and after rotation; and the coordinate system correspondence relationship storage unit maintains the coordinate system correspondence relationship on the basis of the first rotational center position and the second rotational center position corresponding to the second point.

4. The mobile object control system according to Claim 3, wherein:

the first image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of second points within the second image capturing range as center, acquires the first images captured by the first image capturing unit both before rotation and after rotation;

the second image acquisition unit, when the mobile object is sequentially rotated about each of an arbitrary plurality of second points within the second image capturing range as center, acquires the second images captured by the second image capturing unit both before rotation and after rotation;

the first rotational center position specification unit specifies each of the first rotational center positions corresponding to each of the second points on the basis of the first reference guide marks included in each of the first images before rotation and after rotation; the second rotational center position specification unit specifies each of the second rotational center positions corresponding to each of the second points on the basis of the second reference guide marks included in each of the second images before rotation and after rotation; and

the coordinate system correspondence relationship storage unit maintains the coordinate system correspondence relationship on the basis of the first rotational center positions and the second rotational center positions corresponding to each of the second points.

5. The mobile object control system according to any one of Claims 1 through 4, further comprising:

a position specification unit that, by referring to the coordinate system correspondence relationship, specifies a first position of the first guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to an object held by the mobile object that is included in the first image captured by the first image capturing unit, and a second position of the second guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to the object that is included in the second image captured by the second image capturing unit; and

a shift mechanism control unit that, on the basis of an angle subtended by a straight line that connects the first position and the second position in the first image capture coordinate system or the second image capture coordinate system and a target line that is determined in advance in the first image capture coordinate system or the second image capture coordinate system, rotates the mobile object via a shift mechanism around a point as center that is determined in advance within the first image capturing range of the first image capturing unit or within the second image capturing range of the second image capturing unit, so as to shift the object to a target position.

6. The mobile object control system according to Claim 5, wherein the shift mechanism control unit shifts the object to the target position by rotating the mobile object via the shift mechanism around a point as center determined on the basis of the first guide mark or the second guide mark.

7. The mobile object control system according to Claim 5 or Claim 6, wherein:

the shift mechanism comprises two first direction shift mechanisms that shift the mobile object parallel to itself in a first direction that is determined in advance, and a second direction shift mechanism that shifts the mobile object parallel to itself in a second direction that is different from the first direction; and

the shift mechanism control unit rotates the mobile object by controlling each of the two first direction shift mechanisms and the second direction shift mechanism.

8. The mobile object control system according to any one of Claims 5 through 7, further comprising:

a ratio acquisition unit that, when the mobile object has been shifted parallel to itself by an arbitrary distance, acquires the ratio between the actually measured value of the shift distance of the first reference guide mark in the first image capture coordinate system and the actually measured value of the shift distance of the second reference guide mark in the second image capture coordinate system, before parallel shifting and after parallel shifting; a correction coefficient specification unit that specifies a correction coefficient on the basis of the ratio of the actually measured values; and

a parallel shift amount specification unit that, when the object is to be shifted to the target position, specifies a parallel shift amount for the mobile object on the basis of the correction coefficient.

9. The mobile object control system according to any one of Claims 1 through 4, further comprising a rotational angle correspondence relationship storage unit that maintains a rotational angle correspondence relationship that specifies a correspondence relationship between a rotational angle in the first image capture coordinate system or the second image capture coordinate system specified on the basis of the first reference guide mark or the second reference guide mark respectively included in the first image or the second image, and a rotational angle in a mobile object coordinate system that is determined in advance with respect to the mobile object, when the mobile object is rotated a plurality of times about an arbitrary point as center.

10. A program for causing a computer to function as a mobile object control system according to any one of Claims 1 through 9.

11. A mobile object control method, including:

a first image acquisition step of, when a mobile object is rotated around an arbitrary first point as center that is within a first image capturing range of a first image capturing unit that captures first images including a first reference guide mark provided in advance upon the mobile object, acquiring the first images captured by the first image capturing unit before rotation and after rotation;

a second image acquisition step of, when the mobile object is rotated around the first point as center, acquiring second images captured by a second image capturing unit that captures second images including a second reference guide mark provided in advance upon the mobile object before and after rotation;

a first rotational center position specification step of, on the basis of the first reference guide marks included in each of the first images, specifying a first rotational center position corresponding to the first point in a first image capture coordinate system that is determined in advance with respect to the first image capturing unit;

a second rotational center position specification step of, on the basis of the second reference guide marks included in each of the second images, specifying a second rotational center position corresponding to the first point in a second image capture coordinate system that is determined in advance with respect to the second image capturing unit; and

a coordinate system correspondence relationship storage step of, on the basis of the first rotational center position and the second rotational center position, maintaining a coordinate system correspondence relationship that specifies the correspondence relationship between the first image capture coordinate system and the second image capture coordinate system.

12. A mobile object control system, comprising:

a coordinate system correspondence relationship storage unit that maintains a coordinate system correspondence relationship that specifies a correspondence relationship between an image capture coordinate system determined in advance with respect to an image capturing unit that captures an image including a reference guide mark determined in advance with respect to a mobile object, and a mobile object coordinate system determined in advance with respect to the mobile object;

a designated coordinate values specification unit that specifies the coordinate values of an arbitrary point in the image capture coordinate system within the image capturing range or outside the image capturing range as designated coordinate values;

an image acquisition unit that specifies coordinate values in the mobile object coordinate system corresponding to the designated coordinate values on the basis of the coordinate system correspondence relationship, and, when the mobile object is rotationally shifted through an arbitrary rotational angle around the specified coordinate values as center, acquires the images captured by the image capturing unit both before shifting and after shifting;

a rotational center position specification unit that specifies, as rotational center coordinate values, coordinate values in the image capture coordinate system with respect to the rotational center position of the mobile object, on the basis of the reference guide marks included in each of the images, and the rotational angle; and a correspondence relationship correction unit that corrects the coordinate system correspondence relationship on the basis of the coordinate values in the mobile object coordinate system and the rotational center coordinate values.

13. The mobile object control system according to Claim 12, wherein:

the image acquisition unit, when the mobile object is rotationally shifted through arbitrary rotational angles a plurality of times around the specified coordinate values as center, acquires three or more of the images captured by the image capturing unit before shifting and after shifting; and

the rotational center position specification unit specifies, as rotational center coordinate values, coordinate values in the image capture coordinate system with respect to the position of the rotational center of the mobile object on the basis of the respective reference guide marks included in each of the images, and the rotational angles.

14. The mobile object control system according to Claim 12 or Claim 13, wherein:

the designated coordinate values specification unit specifies a plurality of the designated coordinate values;

the image acquisition unit specifies respective coordinate values in the mobile object coordinate system corresponding to the plurality of designated coordinate values on the basis of the coordinate system correspondence relationship, and, when the mobile object is rotationally shifted through an arbitrary rotational angle around the specified coordinate values as center, acquires the images captured by the image capturing unit before shifting and after shifting;

the rotational center position specification unit, for each of the plurality of designated coordinate values, specifies coordinate values in the image capture coordinate system with respect to the rotational center position of the mobile object as rotational center coordinate values, on the basis of the reference guide marks included in each of the images, and the rotational angles; and

the correspondence relationship correction unit corrects the coordinate system correspondence relationship on the basis of the specified coordinate values and the

corresponding rotational center coordinate values.

15. The mobile object control system according to Claim 14, wherein:

the designated coordinate values specification unit specifies a plurality of the designated coordinate values corresponding to coordinate values that are arranged upon a straight line determined in advance in the image capture coordinate system; and

the correspondence relationship correction unit corrects the plurality of rotational center coordinate values specified for each of the plurality of designated coordinate values on the basis of the coordinate values arranged upon a straight line, and corrects the coordinate system correspondence relationship on the basis of the specified coordinate values and the rotational center coordinate values after amendment.

16. The mobile object control system according to any one of Claims 12 through 15, wherein:

the image acquisition unit comprises:

a first image acquisition unit that, when the mobile object is rotated around the designated coordinate values as center, acquires the first images captured by the first image capturing unit that captures a first image including a first reference guide mark determined in advance with respect to the mobile object, both before and after rotation; and

a second image acquisition unit that, when the mobile object is rotated around the designated coordinate values as center, acquires the second images captured by the second image capturing unit that captures a second image including a second reference guide mark determined in advance with respect to the mobile object, both before and after rotation;

the coordinate system correspondence relationship storage unit maintains a correspondence relationship between a first image capture coordinate system of the first image capturing unit and a second image capture coordinate system of the second image capturing unit; and

the rotational center position specification unit specifies a single the rotational center coordinate value in either one of the image capture coordinate systems on the basis of the respective rotational center coordinate values in the first image capture coordinate system and the second image capture coordinate system, specified separately on the basis of the first reference guide mark included in the first image and the second reference guide mark included in the second image.

17. The mobile object control system according to any one of Claims 12 through 15, wherein:

the image acquisition unit comprises:

the coordinate system correspondence relationship storage unit maintains a correspondence relationship between the first image capture coordinate system of the first image capturing unit and the second image capture coordinate system of the second image capturing unit; and

the designated coordinate values specification unit specifies, as designated coordinate values, an arbitrary point upon the perpendicular bisector of a line segment that connects an arbitrary point specified on the basis of the first reference guide mark and an arbitrary point specified on the basis of the second reference guide mark.

18. The mobile object control system according to Claim 16 or Claim 17, further comprising:

a position specification unit that, by referring to the coordinate system correspondence relationship, specifies a first position of a first guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to an object held by the mobile object that is included in the first image captured by the first image capturing unit, and a second position of a second guide mark in the first image capture coordinate system or the second image capture coordinate system determined in advance with respect to the object that is included in the second image captured by the second image capturing unit; and

a shift mechanism control unit that, on the basis of an angle subtended by a straight line that connects the first position and the second position in the first image capture coordinate system or the second image capture coordinate system and a target line that is determined in advance in the first image capture coordinate system or the second image capture coordinate system, rotates the mobile object via a shift mechanism around any arbitrary point as center within the image capturing range or outside the image capturing range, so as to shift the object to a target position.

19. A mobile object control system, comprising:

a coordinate system correspondence relationship storage unit that maintains a coordinate system correspondence relationship specifying a correspondence relationship between an image capture coordinate system determined in advance with respect to an image capturing unit that captures an image including a reference guide mark determined in advance with respect to a mobile object, and a mobile object coordinate system determined in advance with respect to the mobile object;

a designated coordinate values specification unit that specifies, as designated coordinate values, coordinate values of an arbitrary point within the image capturing range of the image capture coordinate system, or outside the image capturing range;

an image acquisition unit that, on the basis of the coordinate system correspondence relationship, specifies coordinate values in the mobile object coordinate system that correspond to the designated coordinate values, and, when the mobile object is rotational shifted through any arbitrary rotational angle around the specified coordinate values as center, acquires the images captured by the image capturing unit before shifting and after shifting; a rotational center position specification unit that specifies coordinate values in the image capture coordinate system with respect to the rotational center position of the mobile object as rotational center coordinate values, on the basis of the reference guide marks included in each of the images and the rotational angle; and

a correspondence relationship correction unit that corrects the coordinate system correspondence relationship on the basis of the rotational center coordinate values and the designated coordinate values;

wherein, when the mobile object shifts in a combination of rotational shifting through any arbitrary rotational angle and shifting parallel to itself, the image acquisition unit acquires the image including the reference guide mark at both time points, before shifting or after shifting.

20. The mobile object control system according to any one of Claims 12 through 19, further comprising a rotational angle correspondence relationship storage unit that maintains a rotational angle correspondence relationship that specifies a correspondence relationship between a rotational angle in the image capture coordinate system specified on the basis of the reference guide marks respectively included in the images, when the mobile object is rotated a plurality of times around an arbitrary point as center, and a rotational angle in a mobile object coordinate system.