Abstract:
A workpiece machining device with a calibration function, which is capable of correcting for positioning such that zero points of an industrial robot and a workpiece coincide with each other, is capable of: simplifying a configuration of a workpiece support as compared to when movement of the work support holding the workpiece is controlled for correction to reduce size and cost of the workpiece machining device, and automating positioning work of making the zero points of the workpiece and the industrial robot coincide with each other to achieve labor-saving of work machining work. Three-dimensional machining data is calibrated based on displacement data in X-, Y-, and Z-axis directions computed by a comparison unit to make the zero points of the industrial robot and the workpiece. The industrial robot is then driven and controlled based on the calibrated three-dimensional machining data to perform machining for the workpiece.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a workpiece machining device with calibration function and a workpiece machining device that drive and control an industrial robot to perform various machining works such as cutting, drilling, and deburring for a workpiece held by a workpiece support. 
         [0003]    More specifically, the present invention relates to a workpiece machining device with calibration function that has function of calibrating (correcting) a zero point of the industrial robot responding to displacement of the workpiece held by the workpiece support and a workpiece machining device. 
         [0004]    2. Description of the Related Art 
         [0005]    The present inventor has proposed, in Jpn. Pat. Appln. Laid-Open Publication No. 2013-52468, a workpiece support that supports a workpiece when a machining tool mounted to a hand portion of an industrial robot is driven and controlled to perform various operations such as drilling, deburring, and cutting for the workpiece. 
         [0006]    In this workpiece support, two workpiece support members adjacently disposed in a longitudinal direction of the workpiece can be positionally adjusted by moving in the front-rear direction orthogonal to the longitudinal direction and left-right direction coinciding with the longitudinal direction, respectively, with respect to other remaining workpiece support members, and can be moved up and down by an identical travel distance by a synchronous vertical drive means, so as to allow mutual intervals between the workpiece support members and heights thereof to be adjusted according to a size of the workpiece and thus to allow the workpiece of various sizes to be held reliably. 
         [0007]    In order to perform a desired machining work for the workpiece held by the workpiece support with high accuracy, it is necessary to position, with high accuracy, the workpiece with respect to the workpiece support such that a zero point of the workpiece and a zero point of the hand portion of a work robot coincide with each other. This positioning operation takes much time and effort, degrading machining workability of the workpiece. 
         [0008]    Particularly, in order to save labor in machining work for the workpiece, it is necessary to automate supply of the workpiece to the workpiece support. However, operator&#39;s visual positioning operation is essential for positioning the workpiece with respect to the workpiece support with high accuracy, which serves an obstacle to the labor-saving in machining work for the workpiece. 
         [0009]    The workpiece support of Jpn. Pat. Appln. Laid-Open Publication No. 2013-52468 can control movement of the individual workpiece support members in the longitudinal direction and up-down direction so as to make correction such that the zero point of the industrial robot and that of the workpiece coincide with each other; however, to this end, it is necessary to control movement of the individual workpiece support members with high resolution, disadvantageously complicating a movement mechanism and a movement control device for each workpiece support member, which in turn results in increase in size and cost of the workpiece support. 
         [0010]    Problems to be solved are as follows. It takes much time and effort in the positioning operation to be performed to make the zero point of the workpiece coincide with the zero point of industrial robot at machining of the workpiece using an industrial robot, degrading machining workability. 
         [0011]    Further, in the case where correction is made such that the workpiece zero point and machine zero point coincide with each other, it is necessary to control movement of the workpiece support member with high resolution, disadvantageously complicating a movement mechanism and a movement control device for each workpiece support member, which in turn results in increase in size and cost of the workpiece support. 
         [0012]    Further, operator&#39;s visual positioning operation is essential for positioning the workpiece with respect to the workpiece support with high accuracy, which serves an obstacle to the labor-saving in machining work for the workpiece. 
       SUMMARY OF THE INVENTION 
       [0013]    According to a first aspect of the present invention, a workpiece machining device with calibration function that drives and control an industrial robot based on three-dimensional machining data in X-, Y-, and Z-axis directions stored in a machining data storage area to perform a desired machining work for a workpiece supported by a workpiece support, the workpiece machining device including: a projection unit that projects a reference pattern onto a predetermined portion of the workpiece supported by the workpiece support; an imaging unit that captures the predetermined portion of the workpiece, including the projected reference pattern and outputs the captured imaging data; a storage unit that includes a three-dimensional reference work data storage area that stores three-dimensional data of the workpiece supported by the workpiece support in a normal state, a three-dimensional imaging data storage area that stores three-dimensional imaging data obtained by converting the imaging data captured by the imaging unit into three-dimensional data, and a pattern data storage area that stores pattern data corresponding to the reference pattern to be projected by the projection unit; a comparison unit that compares the three-dimensional imaging data of the predetermined portion including the reference pattern projected onto the predetermined portion of the workpiece supported by the workpiece support and three-dimensional data of the workpiece stored in the three-dimensional reference work data storage area to compute displacement data in the X-, Y-, and Z-axis directions; and a controller that calibrates three dimensional machining data based on the displacement data in the X-, Y-, and Z-axis directions computed by the comparison unit to make a zero point of the industrial robot and a zero point of the workpiece coincide with each other, wherein the industrial robot is driven and controlled based the calibrated three-dimensional machining data to perform machining for the workpiece. 
         [0014]    According to a second aspect of the present invention, a workpiece machining device with calibration function that drives and control an industrial robot based on three-dimensional machining data in X-, Y-, and Z-axis directions stored in a machining data storage area to perform a desired machining work for a workpiece supported by a workpiece support, the workpiece machining device including: a two-dimensional moving device mounted to a hand portion of an industrial robot and configured to move a workpiece machining tool having an axis coinciding with a normal line of a machining portion of the workpiece in the X- and Y-axis directions; a projection unit that projects a reference pattern onto a predetermined portion of the workpiece supported by the workpiece support; an imaging unit that captures the predetermined portion of the workpiece, including the projected reference pattern and outputs the captured imaging data; a storage unit that includes a three-dimensional reference work data storage area that stores three-dimensional data of the workpiece supported by the workpiece support in a normal state, a three-dimensional imaging data storage area that stores three-dimensional imaging data obtained by converting the imaging data captured by the imaging unit into three-dimensional data, and a pattern data storage area that stores pattern data corresponding to the reference pattern to be projected by the projection unit; a comparison unit that compares the three-dimensional imaging data of the predetermined portion including the reference pattern projected onto the predetermined portion of the workpiece supported by the workpiece support and three-dimensional data of the workpiece stored in the three-dimensional reference work data storage area to compute displacement data in the X-, Y-, and Z-axis directions; and a controller that drives the two-dimensional moving device based on the displacement data in the X- and Y-axis directions computed by the comparison unit to move the machining tool in the X- and Y-axis directions and calibrates three dimensional machining data in Z-axis direction based on the displacement data in the Z-axis direction to make a zero point of the industrial robot and a zero point of the workpiece coincide with each other, wherein the industrial robot is driven and controlled based the calibrated three-dimensional machining data including the Z-axis direction to perform machining for the workpiece. 
         [0015]    According to the present invention, there can be provided a workpiece machining device with calibration function capable of performing correction for positioning such that a zero point of an industrial robot and a zero point of a workpiece coincide with each other with simple operation and in a short time to thereby improve efficiency of a workpiece machining work. 
         [0016]    Further, there can be provided a workpiece machining device with calibration function capable of simplifying a configuration of a workpiece support as compared to a case where movement of the work support holding the workpiece is controlled for correction to thereby reduce a size and cost of the workpiece machining device itself. 
         [0017]    Further, there can be provided a workpiece machining device with calibration function capable of automating a positioning work of making the zero point of the workpiece and zero point of the industrial robot coincide with each other to thereby achieve labor-saving of a work machining work. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view illustrating a schematic outer appearance of a workpiece machining device with calibration function; 
           [0019]      FIG. 2  is side view of the workpiece machining device with calibration function; 
           [0020]      FIG. 3  is a perspective view of a schematic outer appearance of a two-dimensional moving device; 
           [0021]      FIG. 4  is a front view as viewed in a direction of an arrow A of  FIG. 3 ; 
           [0022]      FIG. 5  is a side view as viewed in a direction of an arrow B of  FIG. 3 ; 
           [0023]      FIG. 6  is an electrical block diagram of a controller; 
           [0024]      FIG. 7  is an explanatory view illustrating a state where a workpiece is set to a workpiece support; 
           [0025]      FIG. 8  is a flowchart illustrating workpiece machining processing to be performed by an industrial robot; 
           [0026]      FIG. 9  is a flowchart illustrating calibration processing; 
           [0027]      FIG. 10  is a view illustrating an image of a predetermined portion of the workpiece supported in a normal state; 
           [0028]      FIG. 11  is a view illustrating an image of the predetermined portion of the workpiece supported in a displaced state; 
           [0029]      FIG. 12  is an explanatory view illustrating a two-dimensional position corrected state. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Hereinafter, the present invention will be described based on an embodiment. 
         [0031]    As illustrated in  FIGS. 1 to 5 , a workpiece drilling device  1  as a machining device with calibration function includes a workpiece support  3 , an industrial robot  5 , and a calibrator  7 . 
         [0032]    The workpiece support  3  has a plurality of workpiece support members  11  on a main body frame  9 . The plurality of workpiece support members  11  are arranged in a standing manner spaced apart from each other in a left-right direction and a front-rear direction by a predetermined interval so as to correspond to a longitudinal direction (left-right direction) width and a longitudinal orthogonal direction (front-rear direction) width of a workpiece W to be supported. Each workpiece support member  11  has, at its leading end portion (upper end portion) a holding member  13  that holds the workpiece W to be drilled by supporting a rear surface thereof. 
         [0033]    Any of the following members may be used as the holding member  13 : an elastic member that abuts against the rear surface of the workpiece W to support the workpiece W while regulating displacement by a high friction coefficient; a clamp member having an air cylinder or an electromagnetic solenoid and a grip pawl (all of which are not illustrated) so as to hold a rib (not illustrated) formed in the rear surface of the workpiece W; and an adsorption member (not illustrated) connected to a negative pressure generator to adsorb the rear surface of the workpiece W. 
         [0034]    As the workpiece W to be used in the present invention, a metal formed article and a resin formed article such as various types of panel for vehicle or a bumper for vehicle are suitable. 
         [0035]    The holding member  13  may be configured to be mounted to a vertical movable body supported by a vertical frame vertically extending from a horizontal movable body supported so as to be movable in the longitudinal direction and longitudinal orthogonal direction of the workpiece W and to move in the left-right direction, front-rear direction, and up-down direction with drive of an electric motor such as numerically controllable servo motor connected to the horizontal and vertical movable bodies to change a support position of the workpiece W. 
         [0036]    The industrial robot  5  includes a first arm  19 , a second arm  25 , a hand mounting member  27 , and a hand portion  31 . The first arm  19  has a base end portion rotatably supported by a turn table  14  drive-connected to an electric motor (not illustrated) such as numerically controllable servo motor, incorporated in a base  15  and is connected with an electric motor  17  such as numerically controllable servo motor. The second arm  19  has a base end portion rotatably supported by an arm mounting member (not illustrated) connected to an electric motor (not illustrated) such as numerically controllable servo motor, incorporated in a leading end portion of the first arm  19  and is connected with an electric motor  23  such as numerically controllable servo motor. The hand mounting member  27  is connected to an electric motor (not illustrated) such as a numerically controllable servo motor, incorporated in a leading end of the second arm  25 . The hand portion  31  is mounted to the hand mounting member  27  and configured to perform drilling for the workpiece W. 
         [0037]    The industrial robot  5  may have three or more arms corresponding to the number of rotation shafts and may have, in the base end portion and leading end portion of each arm, the electric motor for rotating a corresponding arm around an axis and in a direction perpendicular to the axis. 
         [0038]    The hand mounting member  27  is attached with a two-dimensional moving device  35 . The two-dimensional moving device  35  includes a first traveling body  39 , a first moving member  41 , a second traveling body  45 , and a second moving member  47 . The first traveling body  39  is supported by a first frame  37  extending in the illustrated left-right direction so as to move in a longitudinal direction of the first frame  37 . The first moving member  41  reciprocates the first traveling body  39  in the longitudinal direction thereof. The second traveling body  45  is supported by a second frame  43  mounted to the first traveling body  39  so as to extend in a direction perpendicular to the left-right direction so as to move in a longitudinal direction of the second frame  43 . The second moving member  47  reciprocates the second traveling body  45  in the longitudinal direction (direction perpendicular to the left-right direction). 
         [0039]    The first and second moving members  41  and  47  may each be of a feed screw moving mechanism that moves the corresponding first traveling body  39  or second traveling body  45  in its predetermined direction with rotation of a feed screw (not illustrated) having an axis in a direction coinciding with the longitudinal direction of the corresponding first frame  37  or second frame  43 , rotatably axially supported by an electric motor such as numerically controllable servo motor connected to one end portion thereof, and partially meshing with a nut provided in the corresponding first traveling body  39  or second traveling body  45 . Alternatively, the first and second moving members  41  and  47  may each be of a belt moving mechanism that moves a traveling member (belt, not illustrated) wound around rotating bodies rotatably axially supported at longitudinal direction both end portions of the first frame  37  or second frame  43 , one of the rotating bodies being rotatably axially supported by an electric motor such as numerically controllable servo motor connected thereto, and partially fixed to the corresponding first traveling body  39  or second traveling body  45  with drive of the electric motor to thereby move the corresponding first traveling body  39  or second traveling body  45  in its predetermined direction. 
         [0040]    Further, alternatively, the first and second moving members  41  and  47  may each be of a rack-and-pinion moving mechanism or a linear servo motor having a configuration in which a pinion gear (not illustrated) mounted to an output shaft of an electric motor such as a numerically controllable servo motor provided in the corresponding first traveling body  39  or second traveling body  45  meshes with a rack gear extending in a direction coinciding with the longitudinal direction of the first frame  37  or second frame  43  and thereby moving the corresponding first traveling body  39  or second traveling body  45  in its predetermined direction with drive of the electric motor. 
         [0041]    The second traveling body  45  is provided with an electric motor  49 , and an endmill  51  as a machining tool for drilling is attached to an output shaft of the electric motor  49 . As the machining tool, a cutting blade, a punch blade, a rule blade, a laser beam output head that performs fusion cutting by means of heat energy of output laser beams, and the like can be selectively used according to machining forms of the workpiece W. 
         [0042]    A guide rail  7   b  mounted to a frame  7   a  of the calibrator  7  is attached with a video camera  53  as an imaging unit and a projector  55  as a projection unit. The video camera  53  and projector  55  are disposed on the guide rail  7   b  above and spaced apart by a predetermined interval from a predetermined portion of the workpiece W held by the workpiece support  3  and spaced apart by a predetermined interval from each other in the left-right direction. The projector  55  projects various reference patterns such as a slit pattern, a lattice pattern, and a dot matrix pattern around the predetermined portion of the workpiece W. The video camera  53  captures the reference pattern projected around and onto the predetermined portion of the workpiece W and outputs imaging data. 
         [0043]    As illustrated in  FIG. 6 , a CPU  59  of a controller  57  that drives and controls the workpiece drilling device  1  is connected with a program storage area  61  and an operation data storage area  63 . The program storage area  61  stores program data for driving and controlling the industrial robot  5  so as to execute drilling for the workpiece W, program data for executing calibration for calibrating the zero point of the workpiece W and zero point of the industrial robot  5 . 
         [0044]    The operation data storage area  63  includes a machining data storage area  65 , a reference work data storage area  67 , an imaging data storage area  69 , a three-dimensional imaging data storage area  71 , a calibration data storage area  73 , and a pattern data storage area  75 . The machining data storage area  65  stores three-dimensional position data concerning a predetermined moving route (including standby position, machining start point, and drilling position of workpiece W) of the hand portion  31  of the industrial robot  5  and a drilling depth. The reference work data storage area  67  stores three-dimensional reference work data of the workpiece W supported by the workpiece support  3  in a normal state (state where the zero point of the workpiece W and zero point of the industrial robot  5  coincide with each other). The imaging data storage area  69  stores imaging data around the predetermined portion of the workpiece W captured by the video camera  53 . The three-dimensional imaging data storage area  71  stores three-dimensional imaging data obtained by converting the imaging data stored in the imaging data storage area  69  into three-dimensional data. The calibration data storage area  73  stores calibration data. The pattern data storage area  75  stores pattern data corresponding to a single or a plurality of patterns to be projected onto the workpiece W. 
         [0045]    The predetermined portion of the workpiece W to be captured by the video camera  53  desirably includes a reference portion Wa, such as an opening portion, a step portion, or a projecting portion (opening portion, in the case of  FIG. 10 ), serving as a reference for determining two-dimensional displacement. In the absence of the reference portion Wa, reference portions are set for the workpiece support  3  at portions corresponding to both sides of the workpiece W in the longitudinal direction or longitudinal orthogonal direction thereof, and the video camera  53  is used to capture the predetermined portion of the workpiece W, including the reference lines thus set for the workpiece support  3 . 
         [0046]    The data to be stored in the machining data storage area  65 , reference work data storage area  67 , and three-dimensional imaging data storage area  71  store the data as world coordinate system data. The reference work data to be stored in the reference work data storage area  67  may be set as the world coordinate system data by directly inputting a three-dimensional position of the workpiece W supported by the workpiece support  3  in the normal state; alternatively, data obtained by synthesizing height data of the workpiece W supported by the workpiece support  3  in the normal state and CAD data of the workpiece W may be set as the world coordinate system data. 
         [0047]    The CPU  59  is further connected with a comparison unit  77 . The comparison unit  77  compares the three-dimensional imaging data stored in the three-dimensional imaging data storage area  71  and three-dimensional reference work data stored in the reference work data storage area  67 , computes a three-dimensional displacement amount as calibration data, and stores the computed calibration data in the calibration data storage area  73 . 
         [0048]    The CPU  59  is further connected with a robot controller  79 . The robot controller  79  drives and controls the not illustrated electric motors and illustrated electric motors  17  and  23  based on the three-dimensional position data stored in the machining data storage area  65  to move the hand portion  31  to the zero point and then to drilling position and executes the drilling. 
         [0049]    The CPU  59  is further connected with a two-dimensional movement controller  81 . The two-dimensional movement controller  81  drives and controls, when the zero point of the hand portion  31  does not coincide with the zero point of the workpiece W supported by the workpiece support  3 , the first and second moving members  41  and  47  based on the calibration data stored in the calibration data storage area  73  to two-dimensionally move the endmill  51  to thereby make the machine zero point and workpiece zero point coincide with each other. 
         [0050]    The CPU  59  is further connected with a projection controller  83 . The projection controller  83  drives, prior to the drilling to be performed for the workpiece W supported by the work support  3 , the projector  55  based on the single or plurality of pattern data read out from the pattern data storage area  75  to project the reference pattern onto a surface corresponding to the predetermined portion of the workpiece W. 
         [0051]    In projecting the plurality of reference patterns onto the workpiece W, the projection controller  83  drives the projector  55  for each image capture time (to be described later) of the video camera  53  based on the pattern data read out, in a prescribed order, from the pattern data storage area  75  to project the reference patterns. 
         [0052]    The CPU  59  is further connected with an imaging controller  85 . The imaging controller  85  drives the video camera  53  for image capture at timing when the reference pattern is projected onto the workpiece W supported by the workpiece support  3  to capture a surface of the workpiece W around the predetermined portion including the reference pattern and then store the captured imaging data in the imaging data storage area  69 . 
         [0053]    In a case where the plurality of reference patterns are projected onto the workpiece W from the projector  55 , the imaging controller  85  drives the video camera  53  for image capture every time the reference pattern to be projected is changed and stores imaging data around the predetermined portion of the workpiece W including the reference patterns in the imaging data storage area  69 . 
         [0054]    The CPU  59  is further connected, through an interface  89 , with a plurality of detectors  87  such as a limit switch that detects a state where the workpiece W is supported by the workpiece support  3 . When all the plurality of detectors  87  detects the above state, the CPU  59  determines that the workpiece W is supported by the workpiece support  3  and allows the projector  55  and video camera  53  to perform projection and image capturing, respectively. 
         [0055]    The following describes the drilling operation and calibration processing to be performed by the workpiece drilling device  1  having the above configuration. 
         [0056]    First, an overview of the drilling operation to be performed by the workpiece drilling device  1  will be described. As illustrated in  FIG. 8 , in step  101 , when the workpiece W is set to the workpiece support  3  (see  FIG. 7 ), it is determined whether or not all the detectors  87  are in a workpiece detection state. When a negative determination is made in step  101 , the processing flow returns to step  101 . 
         [0057]    On the other hand, when a positive determination is made in step  101 , the calibration processing is executed in step  103  to make the zero point of the industrial robot  5  and zero point of the workpiece W supported by the workpiece support  3  coincide with each other. 
         [0058]    Then, in step  105 , the not illustrated electric motors and illustrated electric motors  17  and  23  are driven and controlled based on the three-dimensional position data concerning the machine zero point stored in the machining data storage area  65  to swing and rotate the first and second arms  19  and  25 , and the hand mounting member  27  is rotated to move the endmill  51  of the hand portion  31  such that an axis of the endmill  51  coincides with a normal line of the zero point of the workpiece W. Subsequently, in step  107 , the electric motor  49  is driven to move the endmill  51  based on the three-dimensional position data while rotating the same to thereby drill a hole of a predetermined size and a predetermined depth in the workpiece W. 
         [0059]    Then, in step  109 , the first and second arms  19  and  25  are swung and rotated based on the three-dimensional position data stored in the machining data storage area  65 , and the hand mounting member  27  is rotated as needed to extract the endmill  51  from the drilled hole. Subsequently, in step  111 , the first and second arms  19  and  25  are swung and rotated based on the three-dimensional position data stored in the machining data storage area  65 , and the hand mounting member  27  is rotated as needed to move the endmill  51  such that the axis of the endmill  51  coincides with a normal line of a next machining position. 
         [0060]    Then, in step  113 , it is determined whether or not the endmill  51  has moved to the next machining position. When a negative determination is made, the processing flow returns to step  111 . On the other hand, when a positive determination is made in step  113 , the following operation is performed. That is, in step  115 , in the same manner as described above, the electric motor  49  is driven to move the endmill  51  based on the three-dimensional position data while rotating the same to thereby drill a hole of a predetermined size and a predetermined depth in the workpiece W, and, in step  117 , the first and second arms  19  and  25  are swung and rotated based on the three-dimensional position data stored in the machining data storage area  65 , and the hand mounting member  27  is rotated as needed to extract the endmill  51  from the drilled hole. 
         [0061]    Then, in step  119 , it is determined whether or not all the machining positions of the workpiece W have been drilled. When a negative determination is made in step  119 , the processing flow returns to step  111 , where the drilling operation for the next **** is executed. 
         [0062]    On the other hand, when a positive determination is made in step  119 , the following operation is performed. That is, in step  121 , the first and second arms  19  and  25  are swung and rotated based on three-dimensional position data concerning a standby position stored in the machining data storage area  65 , and the hand mounting member  27  is rotated as needed to move the hand portion  31  to the standby position, and, in step  123 , completion of the machining work is notified by lighting a lamp or issuing a buzzer, and this routine is ended. 
         [0063]    The following describes details of the calibration processing to be performed in step  103 . As illustrated in  FIG. 9 , in step  131 , the projector  55  is driven based on the pattern data stored in the pattern data storage area  75  to project the reference pattern onto the predetermined portion of the workpiece W supported by the workpiece support  3 . Subsequently, in step  133 , the video camera  53  is driven to capture the surface of the predetermined portion of the workpiece W including the projected reference pattern and stores the captured imaging data in the imaging data storage area  69 . 
         [0064]    In step  135 , the imaging data stored in the imaging data storage area  69  is converted into the three-dimensional imaging data, and the obtained three-dimensional imaging data is stored in the three-dimensional imaging data storage area  71 . Subsequently, in step  137 , the comparison unit  77  compares the three-dimensional imaging data stored in the three-dimensional imaging data storage area  71  and three-dimensional reference work data corresponding to the captured portion stored in the reference work data storage area  67 . 
         [0065]    In the comparison to be performed by the comparison unit  77 , the three-dimensional imaging data of the opening portion Wa and three-dimensional reference work data are compared in terms of two-dimensional position, and a slit interval of the projected reference pattern in the three-dimensional data and a slit interval of the pattern data stored in the pattern data storage area  75  are compared in terms of displacement in the height direction. 
         [0066]    Then, in step S 139 , it is determined whether or not a difference in the pattern data is present between the three-dimensional imaging data and three-dimensional reference work data. When a negative determination is made in step  139 , it is determined that the workpiece W is in the normal state with respect to the workpiece support  3  as illustrated in  FIG. 10 , that is, it is determined that the zero point of the endmill  51  and zero point of the workpiece W coincide with each other, and this routine is ended. 
         [0067]    On the other hand, when a positive determination is made in step  139 , it is determined that the zero point of the workpiece W supported by the workpiece support  3  and zero point of endmill  51  are displaced from each other as illustrated in  FIG. 11 . Then, in step  141 , a three-dimensional difference is computed, and calculated displacement amount in each of the X-, Y-, and Z-axis directions is stored in the calibration data storage area  73  as the calibration data. 
         [0068]    Subsequently, in step  143 , the first and second moving members  41  and  47  are driven and controlled based on two-dimensional calibration data in the X- and Y-axis directions included in the calibration data read out from the calibration data storage area  73  to make a leading end (machine zero point) of the endmill  51  coincide with the zero point of the workpiece W (see  FIG. 12 ). 
         [0069]    Further, in step  154 , Z-axis direction data of the three-dimensional position data concerning the machining position stored in the machining data storage area  65  is corrected using calibration data in the Z-axis direction included in the calibration data read out from the calibration data storage area  73 , and the calibration processing is ended. 
         [0070]    In the present embodiment, the video camera  55  is used to capture the predetermined portion of the workpiece W including the projected reference pattern after the workpiece W is set to the workpiece support  3 , and the three-dimensional imaging data obtained by conversion based on the captured imaging data and three-dimensional reference work data are compared to compute displacement between the zero point of the industrial robot  5  and zero point of the workpiece W. Then, the two-dimensional moving device  35  is driven and controlled based on data in the X- and Y-axis directions included in the computed calibration data to make the zero point of endmill  51  coincide with the zero point of the workpiece W and the three-dimensional machining data is calibrated based on the Z-axis direction data, and the industrial robot  5  is driven and controlled based on the calibrated three-dimensional machining data to perform a predetermined machining work for the workpiece W. 
         [0071]    Thus, even when the workpiece W is set to the workpiece support  3  in a non-positioned state, it is possible to perform a desired machining work for a prescribed position on the workpiece W with high quality while reducing time and effort of the positioning work of the workpiece W with respect to the workpiece support  3 . 
         [0072]    In the above description, the two-dimensional moving device  35  is driven and controlled based on the data in the X- and Y-axis directions included in the computed calibration data to make the zero point of the endmill  51  coincide with the zero point of the workpiece W; however, a configuration may be possible in which the three-dimensional machining data is calibrated based on calibration data in the X-, Y-, and Z-axis directions and the industrial robot  5  is driven and controlled based on the calibrated three-dimensional machining data to make the zero point of the industrial robot  5  and zero point of the workpiece W coincide with each other.