Method and system for estimating normal vector to die and normal vector to attachment

A method of estimating a normal vector to an attachment mounted to an approach frame of an apparatus for taking out a molded product and a normal vector to a die mounted to a molding machine is provided. A normal vector to a take-out head is estimated through computation using a coordinate/depth determination section and a normal vector computation section on the basis of depth data or coordinate data on three mounting members. Three or more extending portions are specified from the image, the extending portions being each a part of a fixed die or a movable die or a part of a surrounding component and extending in a direction that coincides with the open direction for the dies. A normal vector to the die is estimated through computation on the basis of the depth data or coordinate data on the specified extending portions.

TECHNICAL FIELD

The present invention relates to a method and system for estimating a normal vector to an attachment mounted to an approach frame of an apparatus for taking out a molded product and a normal vector to a die mounted to a molding machine.

BACKGROUND ART

Japanese Unexamined Patent Application Publication No. 2002-120175 (Patent Document 1) discloses an invention related to teaching of an apparatus for taking out a molded product. In the related art, when taking out a molded product from a die of a molding machine, an operator performs setting work for a teaching program for programming beforehand the path of an approach frame of the apparatus for taking out a molded product and the posture of a take-out head (attachment) mounted to the approach frame, while moving the take-out head while seeing the relationship between the take-out head and the die such that the take-out head does not collide with the die.

SUMMARY OF INVENTION

Technical Problem

When the above work is performed, the take-out head occasionally collides with the die to damage the die. This problem is caused by an assumption by the operator that the status of installation of the die in the molding machine and the mounting state of constituent components of the take-out head are invariable at all times. In reality, however, the mounting state of the take-out head is not always constant. Under such circumstances, a high degree of proficiency and a sharp eye are required from the operator to prepare or correct the teaching program such that the take-out head does not collide with the die. If the take-out head is tilted with respect to the die, there is an apprehension that the take-out head contacts the die when the take-out head approaches the die or that the die is damaged when their surfaces are caused to abut against each other. Thus, it is necessary to grasp the tilt between the take-out head and the die, and correct the tilt when the take-out head approaches the die or when their surfaces are caused to abut against each other.

In consideration of automation or precision enhancement of the teaching, it is necessary to know the mounting state of the die and the attachment. The mounting state of the die and the attachment can be recognized by knowing a normal vector to the attachment and a normal vector to the die which is mounted to the molding machine.

It is an object of the present invention to provide a method and system for estimating a normal vector to an attachment mounted to an approach frame of an apparatus for taking out a molded product and a normal vector to a die mounted to a molding machine.

Solution to Problem

The present invention provides a method of estimating a normal vector to an attachment mounted to an approach frame of an apparatus for taking out a molded product and a normal vector to a die mounted to a molding machine. In the present invention, a vector that is perpendicular to respective mating surfaces of a fixed die and a movable die of the die mounted to the molding machine is defined as the normal vector to the die, and a vector that is perpendicular to an imaginary plane that extends in directions in which the approach frame extends and that is parallel to the mating surfaces when the attachment is inserted between the fixed die and the movable die is defined as the normal vector to the attachment. Herein, the movable die includes a common intermediate die interposed between the fixed die and the movable die. The method includes capturing an image including a surrounding component located around the mating surface of the fixed die or the mating surface of the movable die using an imaging device capable of capturing an image including depth data or coordinate data on an object to be captured, specifying three or more extending portions from the image, the extending portions being each a part of the fixed die or the movable die or a part of the surrounding component and extending in a direction that coincides with an open/close direction for the fixed die and the movable die, and estimating the normal vector to the die on the basis of depth data or coordinate data on the specified three or more extending portions. Herein, the “depth data” are data including coordinate data on the position of a dot obtained from dot group data obtained from a three-dimensional imaging device. That is, the depth data refer to information on the direction (specified by angles) of an object as seen from the imaging device (camera) and a distance r when the object is seen from the imaging device. The “coordinate data” refer to a coordinate P (x, y, z) of the object in an xyz orthogonal coordinate system with the imaging device (camera) located at the origin. The depth data can be converted into the coordinate data.

In the present invention, the method also includes capturing an image including three or more mounting members or three or more contact members using an imaging device capable of capturing an image including depth data or coordinate data on an object to be captured, the mounting members extending in a direction that is orthogonal to the approach frame to mount the attachment to the approach frame, and the contact members contacting the molded product, and estimating the normal vector to the attachment on the basis of the depth data or the coordinate data on three of the mounting members or three of the contact members obtained from the image. A three-dimensional imaging device can be used as the imaging device that outputs the depth data and the coordinate data. A known mathematical method can be used as a method of estimating a normal vector from data on three or more points on the basis of the depth data or the coordinate data. With the present invention, image data including depth data or coordinate data obtained from the die and the attachment to be actually used are sampled by the imaging device to estimate a normal vector to the attachment and a normal vector to the die. Thus, normal vectors closely related to the actual mounting state of the die and the attachment can be estimated. Thus, it is possible to easily implement automation of teaching, control for the posture of the attachment, etc.

The present invention may be grasped as a method of estimating a normal vector to a die mounted to a molding machine. Also in this case, a vector that is perpendicular to respective mating surfaces of a fixed die and a movable die of the die mounted to the molding machine is defined as the normal vector to the die. The method includes capturing an image including a surrounding component located around the mating surface of the fixed die or the mating surface of the movable die using an imaging device capable of capturing an image including depth data or coordinate data on an object to be captured. The method also includes specifying three or more extending portions from the image, the extending portions being each apart of the fixed die or the movable die or a part of the surrounding component and extending in a direction that coincides with an open/close direction for the fixed die and the movable die, and estimating the normal vector to the die on the basis of the depth data or the coordinate data on the specified three or more extending portions.

The present invention may also be grasped as a method of estimating a normal vector to an attachment mounted to an approach frame of an apparatus for taking out a molded product. Also in this case, a vector that is perpendicular to an imaginary plane that extends in a direction in which the approach frame extends and that is parallel to mating surfaces when the attachment is inserted between a fixed die and a movable die is defined as the normal vector to the attachment. The method includes capturing an image including three or more mounting members or three or more contact members using an imaging device capable of capturing an image including depth data or coordinate data on an object to be captured, the mounting members extending in a direction that is orthogonal to the approach frame to mount the attachment to the approach frame, and the contact members contacting the molded product. The method also includes estimating the normal vector to the attachment on the basis of the depth data or the coordinate data on three of the mounting members or three of the contact members obtained from the image.

The extending portions may be guide pins of the die, edge surfaces of the fixed die or the movable die, tie bars, etc.

The mounting members may be mounting bolts or edge surfaces of amounting fitting (mounting plate), for example. The contact members may be suction pads, for example.

The imaging devices may each be a three-dimensional imaging device capable of capturing an image including a mating surface of one of the movable die and the fixed die of the die in an open state, and disposed so as to be capable of capturing an image including a take-out surface of the attachment when the attachment is located outside the die.

A posture of an attachment when inserting the attachment into a die can be determined using the normal vector to the die and the normal vector to the attachment estimated using the method of estimating normal vectors according to the present invention, the posture of the attachment being determined so as to take out a molded product in such a posture that the normal vector to the die and the normal vector to the attachment coincide with each other.

In addition, maximum three-dimensional dimensions of an attachment can be accurately measured using the normal vector to the attachment estimated using the method of estimating a normal vector according to the present invention and the image from the imaging device, the normal vector to the attachment being determined as a vector extending along a one-dimensional dimension of three-dimensional dimensions.

Further, the invention can be grasped as a system for estimating a normal vector to an attachment mounted to an approach frame of an apparatus for taking out a molded product and a normal vector to a die mounted to a molding machine. The system according to the present invention includes a processor. A vector that is perpendicular to respective mating surfaces of a fixed die and a movable die of the die mounted to the molding machine is defined as the normal vector to the die, and a vector that is perpendicular to an imaginary plane that extends in directions in which the approach frame extends and that is parallel to the mating surfaces when the attachment is inserted between the fixed die and the movable die is defined as the normal vector to the attachment. The processor is configured to obtain depth data or coordinate data on three or more extending portions specified from an image captured using a first imaging device capable of capturing an image including depth data or coordinate data on an object to be captured, the image including a surrounding component located around the mating surface of the fixed die or the mating surface of the movable die, and the extending portions being each a part of the fixed die or the movable die or a part of the surrounding component and extending in a direction that coincides with an open/close direction for the fixed die and the movable die, and estimate the normal vector to the die on the basis of the depth data or the coordinate data. The processor is further configured to obtain depth data or coordinate data on three mounting members or three contact members specified from an image captured using a second imaging device capable of capturing an image including depth data or coordinate data on an object to be captured, the image including three or more mounting members or three or more contact members, the mounting members extending in a direction that is orthogonal to the approach frame to mount the attachment to the approach frame, and the contact members contacting the molded product, and estimate the normal vector to the attachment on the basis of the depth data or the coordinate data.

DESCRIPTION OF EMBODIMENTS

A normal vector estimation method according to an embodiment of the present invention will be described in detail below with reference to the drawings.FIGS.1to4are a perspective view, a left side view, a front view, and a plan view, respectively, of a molded product manufacturing system1including an orthogonal three-axis robot which has operation shafts extending in the X direction, the Y direction, and the Z direction and to which a normal vector estimation method and a maximum dimension measurement method according to the present invention can be applied. InFIG.1, the X direction, the Y direction, and the Z direction which are used in the present embodiment are indicated. The molded product manufacturing system1is constituted by assembling a molding machine3operable to manufacture a resin molded product and an apparatus5for taking out a molded product, as the orthogonal three-axis robot. The apparatus5is a traverse-type apparatus for taking out a molded product. A base portion of the apparatus5is supported by a fixed platen30of the resin molding machine3.

A fixed die31and an intermediate die32are fixed to the fixed platen30of the molding machine3. A movable die34is fixed to a movable platen33. Four tie bars35A to35D are disposed between the fixed platen30and the movable platen33to guide movement of the movable platen33. The four tie bars35A to35D are disposed at equal intervals. A virtual center line that passes through the center of the four tie bars35A to35D passes through the center (nozzle center) of the fixed die31and the movable die34. The fixed die31, the intermediate die32, and the movable die34are guided by guide pins36A to36D. The four guide pins36A to36D are also disposed at equal intervals. A virtual center line that passes through the center of the four guide pins36A to36D also passes through the center (nozzle center) of the fixed die31and the movable die34.

The apparatus5includes a transverse shaft53, a first transfer body55, a pull-out shaft57, a runner elevating unit58, and a molded product-suctioning elevating unit59. The transverse shaft53has a cantilever beam structure in which the transverse shaft53extends in the X direction which is horizontal and orthogonal to the longitudinal direction of the molding machine3. The first transfer body55is supported by the transverse shaft53, and advanced and retracted in the X direction along the transverse shaft53by a drive source formed by an AC servomotor included in a servomechanism. The pull-out shaft57is provided on the first transfer body55to extend in the Y direction which is parallel to the longitudinal direction of the molding machine. The runner elevating unit58and the molded product-suctioning elevating unit59are supported on the pull-out shaft57to be movable in the Y direction by a drive source formed by an AC servomotor included in the servomechanism. The runner elevating unit58is structured to include an elevating frame58B provided on a travelling body58A, which is movably supported on the pull-out shaft57, to be elevated and lowered in the Z direction. A travelling body59A is driven by an AC servomotor to be moved in the Y direction. The elevating frame58B is elevated and lowered in the up-down direction (Z direction) by a drive source. The elevating frame58B includes a chuck58C that serves as an attachment for holding a runner to be wasted.

The travelling body59A which is included in the molded product-suctioning elevating unit59is driven by an AC servomotor to be moved in the Y direction on the pull-out frame57. The molded product-suctioning elevating unit59includes an elevating frame59B, a reverse unit59C, and a take-out head60. The elevating frame59B is elevated and lowered in the up-down direction (Z direction) by a drive source. The reverse unit59C serves as a posture controller to be rotated about the axis of the elevating frame59B. The take-out head60is provided on the reverse unit59C. In the present embodiment, maximum dimensions of the take-out head60as the attachment are measured. In this embodiment, the normal vector to the take-out head60is estimated when estimating the maximum dimensions of the take-out head60as an attachment.

In the present embodiment, in order to make a trial search for a preferable installation position, eight imaging devices C1to C8are installed at various portions of the apparatus5and the molding machine3and on a stand7placed at a side of the molding machine3. Two-dimensional cameras or three-dimensional cameras are used as the imaging devices C1to C8. In the present embodiment, a necessary image can be obtained by selecting one of the imaging devices C1to C8that provides a preferable image.

FIG.5is a block diagram illustrating the configuration of a measurement system constructed in a control system1for the apparatus5, in order to apply the method of measuring the three-dimensional geometry of an attachment according to the present embodiment.FIG.6indicates the maximum dimensions of the take-out head60.FIGS.7A-8Eare image display for illustrating the method according to the present embodiment.

In the method of measuring the maximum dimensions using the method of estimating vectors according to the present embodiment, a maximum dimension of the take-out head60, as the attachment, in the X direction, a maximum dimension of the take-out head (attachment)60in the Y direction, and a maximum dimension of the take-out head (attachment)60in the Z direction are measured on the basis of an image of the take-out head60captured by at least one of the imaging devices (C1to C8) before the take-out head60starts work with the take-out head60being mounted to the elevating frame59B, as the work frame, of the apparatus5, as the orthogonal three-axis robot. Preferably, the three-dimensional position coordinate of the at least one imaging device at the time of capturing an image of the take-out head60, the three-dimensional position coordinate of the take-out head60of which an image is captured, the field angle of the imaging device, and the mounting posture of the take-out head60to the elevating frame59B (work frame) are determined so that the image captured by the imaging device includes information needed to measure the three-dimensional geometry of the take-out head60, depending on the measurement method to be used. As more information such as coordinate information, the field angle of the imaging device, and the mounting posture is available beforehand, computation for measurement of the maximum dimensions on the basis of the image can be facilitated, and computation for correction of the image data on the basis of the difference in the mounting position and the mounting posture of the imaging device can be reduced.

Then, the method of estimating normal vector to attachment according to the present invention can be used to obtain field angel information of the imaging device. Namely, if a normal vector to the attachment can be known, an angle of the normal vector can coincide with the field angle of the imaging device.

When measurement of the maximum dimensions is performed using the system illustrated in the block diagram inFIG.5, in order to measure maximum dimensions in accordance with an operation by an operator, an imaging system71including the at least one imaging device includes a first imaging device C11configured to obtain a first image of the take-out head60in such a posture that allows measurement of the maximum dimension of the take-out head60in the X direction and the maximum dimension of the take-out head60in the Z direction, a second imaging device C12configured to obtain a second image of the take-out head60in such a posture that allows measurement of the maximum dimension of the take-out head60in the Y direction and the maximum dimension of the take-out head60in the Z direction, and an image display device72that includes a screen73with indicators on orthogonal coordinate axes for displaying the first image or the second image. The screen73with indicators on orthogonal coordinate axes is a gauge screen having two orthogonal axes (GZ-GX, GZ-GY).

In the present embodiment, an X-direction drive source74and an X-direction movement amount measurement unit75configured to move the elevating frame59B in the X direction, a Y-direction drive source76and a Y-direction movement amount measurement unit75configured to move the elevating frame59B in the Y direction, and a Z-direction drive source78and a Z-direction movement amount measurement unit79configured to move the elevating frame59B in the Z direction are used. The operator performs the following operation using an operation portion97constituted of an operation switch etc. provided on a controller. In the following operation, image display on the screen73of the image display device72is performed by an image control section96in a control device90constituted in a control section for the apparatus5. The computation of the maximum dimensions is performed in a dimension computation section95on the basis of outputs from the X-direction movement amount measurement unit75, Y-direction movement amount measurement unit77, and Z-direction movement amount measurement unit79. The control device90includes a processor configured to implement a maximum dimension computation section95that constitutes the dimension measurement section. Computation of maximum dimensions is performed by the dimension computation section95, as the dimension measurement section, on the basis of outputs from the X-direction movement amount measurement unit75to the Z-direction movement amount measurement unit79. A drive control section94outputs an operation command for the X-direction drive source75to the Z-direction drive source78in accordance with an operation from the operation portion97. The control device90further includes a teaching section91configured to perform an operation for teaching to be described later, a data storage section92configured to store teaching data, and a possibility-of-use determination section93.

Specifically, the imaging device C1or C2illustrated inFIGS.1to4can be used as the first imaging device C11, if the posture of the take-out head60is not varied. The first imaging device C11captures an image of the take-out head60, as the attachment, from the front. Meanwhile, the imaging devices C6to C8illustrated inFIGS.1to4can be used as the second imaging device C12, if the posture of the take-out head60is not varied. The imaging devices C1to C5illustrated inFIGS.1to4can be used if the posture of the take-out head60is varied. The first imaging device C11captures an image of the take-out head60, as the attachment, from the front. The second imaging device C12captures an image of the take-out head60from a side. When disposing the first and second imaging devices C11and C12respectively at the front and side of the take-out head60, the method of estimating normal vectors of the present invention can be used.

Specifically, as illustrated inFIGS.7A-7H, the direction in which orthogonal coordinate axes GZ and GX for indicators G on the screen73extend and the X direction and the Z direction in the first image from the first imaging device C11are caused to coincide with each other. This state is established while seeing an image of the screen73and an image of the indicator G. Then, the maximum dimension in the Z direction is computed on the basis of the distance [see Zs-Ze inFIG.6] measured by the Z-direction movement amount measurement unit79, which is constituted of an encoder etc., during a period since a suction pad60A, which is an outermost end portion, on one side in the Z direction, of the take-out head60in the first image crosses a reference line (GX in the present example) on the screen (the value measured at this time is defined as Zs) until a suction pad60B, which is an outermost end portion, on the other side in the Z direction, of the take-out head60crosses the reference line (GX in the present example) (the value measured at this time is defined as Ze) [FIGS.7A to7D] while the take-out head60is moved in the Z direction by driving the Z-direction drive source78, which is constituted of a servomotor etc.

In addition, the maximum dimension in the X direction is measured on the basis of the distance [see Xs-Xe inFIG.6] measured by the X-direction movement amount measurement unit during a period since a suction pad60C, which is an outermost end portion, on one side in the X direction, of the take-out head60in the first image crosses a reference line (GZ in the present example) on the screen (the value measured at this time is defined as Xs) until a suction pad60D, which is an outermost end portion, on the other side in the X direction, of the take-out head60crosses the reference line (GZ) (the value measured at this time is defined as Xe) while the take-out head60is moved in the X direction by driving the X-direction drive source74with directions in which the orthogonal coordinate axes GZ and GY for the indicators G on the screen73extend coinciding with the X direction and the Z direction in the first image.

Further, as illustrated inFIGS.8A-8E, the maximum dimension in the Y direction is measured on the basis of the distance [see Ys-Ye inFIG.6] measured by the Y-direction movement amount measurement unit during a period since an outermost end portion60E, on one side in the Y direction, of the take-out head60in the second image crosses a reference line (GZ in the present example) on the screen (the value measured at this time is defined as Ys) until an outermost end portion60F, on the other side in the Y direction, of the take-out head60crosses the reference line (GZ) (the value measured at this time is defined as Ye) while the take-out head60is moved in the Y direction by driving the Y-direction drive source76with directions in which the orthogonal coordinate axes GZ and GY for the indicators G on the screen73extend coinciding with the Y direction and the Z direction in the second image (side image).

With the method of estimating the maximum dimensions, it is possible to measure maximum dimensions in the X direction, the Y direction, and the Z direction using simple equipment and through an easy operation. Parts mounted to the take-out head60, which is mounted to the elevating frame59B of the apparatus5, are often replaced with parts different from those according to the design specifications for repair, or the arrangement posture of such parts is occasionally varied for maintenance. For example, the take-out head60which is mounted to the elevating frame59B, as the work frame, is constituted with an accessory part including an air tube for providing power to the take-out head60or a wire. Therefore, the position and the posture of the air tube or the wire may be varied each time the take-out head60is replaced. The operator may mount a wrong take-out head to the elevating frame59B. Even in such cases, a change in the shape of the take-out head60to be actually used can be determined, before take-out work performed using the take-out head60is actually started, by measuring the maximum dimensions of the take-out head60in the X, Y, and Z directions with the take-out head60mounted to the elevating frame59B. As a result, it is possible to detect, beforehand, collision of the take-out head60with a part etc. located in the movement path or mounting of a wrong take-out head.

FIG.9is a block diagram illustrating the configuration of a measurement system that is used to measure maximum dimensions using a single three-dimensional imaging device C13as the imaging device. In this measurement system, maximum dimensions are measured using, as the imaging device, the three-dimensional imaging device C13which measures an object surface to output dot group data including a large number of dots each having a three-dimensional coordinate. A first dot group data acquisition section101A acquires, from image data obtained when the three-dimensional imaging device C13captures an image of the take-out head60from the front, first dot group data that allow measurement of the maximum dimension of the take-out head60in the X direction and the maximum dimension of the take-out head60in the Z direction. Meanwhile, a second dot group data acquisition section101B acquires, from image data obtained when the three-dimensional imaging device C13captures an image of the take-out head60from a side, second dot group data that allow measurement of the maximum dimension of the take-out head60in the Y direction and the maximum dimension of the take-out head60in the Z direction. When disposing the three-dimensional imaging device C13at the front or side of the take-out head60, the method of estimating normal vectors of the present invention can be used. When a single three-dimensional imaging device is used, the imaging device C1inFIG.1may be used as the three-dimensional imaging device, and may acquire a front image and thereafter rotate the take-out head60by 90 degrees using the reverse unit59C, as the posture change device, to acquire a side image. As a matter of course, two three-dimensional imaging devices may be used to obtain a front image and a side image.

A maximum dimension determination section100, as the dimension computation section constituted by a processor in a control device90′, measures the maximum dimension in the Z direction on the basis of the coordinate of a dot positioned at the outermost end, on one side in the Z direction, among the dots in the first dot group data, and the coordinate of a dot positioned at the outermost end, on the other side in the Z direction, among the dots in the first dot group data. The maximum dimension determination section100also measures the maximum dimension in the X direction on the basis of the coordinate of a dot positioned at the outermost end, on one side in the X direction, among the dots in the first dot group data, and the coordinate of a dot positioned at the outermost end, on the other side in the X direction, among the dots in the first dot group data. The maximum dimension determination section100further measures the maximum dimension in the Y direction on the basis of the coordinate of a dot positioned at the outermost end, on one side in the Y direction, among the dots in the second dot group data, and the coordinate of a dot positioned at the outermost end, on the other side in the Y direction, among the dots in the second dot group data.

The dot group data obtained through the three-dimensional imaging device are a data file containing, as a dot group, a large number of three-dimensional coordinates obtained by automatically measuring an object surface. That is, each dot constituting the dot group includes three-dimensional coordinate information. Thus, when an image of the take-out head60illustrated inFIG.10Ais captured by the three-dimensional imaging device, dot group data illustrated inFIG.10Bare obtained. Each dot includes three-dimensional coordinate information. Thus, as illustrated inFIGS.10C and10D, the maximum dimension determination section100calculates the coordinate values of a dot with the largest coordinate in the X direction and a dot with the smallest coordinate in the X direction, among dots in the dot group data at the same depth in the X direction (having the same Y coordinate value), and determines the difference between such coordinate values as a maximum dimension Xm in the X direction. In addition, the maximum dimension determination section100calculates the coordinate values of a dot with the largest coordinate in the Z direction and a dot with the smallest coordinate in the Z direction, among dots in the dot group data at the same depth in the Z direction (having the same Y coordinate value), and determines the difference between such coordinate values as a maximum dimension Zm in the Z direction. Next, as illustrated inFIG.11, the maximum dimension determination section100calculates the coordinate values of a dot with the largest coordinate in the Y direction and a dot with the smallest coordinate in the Y direction, among dots in the dot group data acquired by the second dot group data acquisition section101B at the same depth in the Y direction (having the same X coordinate value), and determines the difference between such coordinate values as a maximum dimension Ym in the Y direction. In this manner, the three-dimensional maximum dimensions Xm, Ym, and Zm of the take-out head60can be obtained from the dot group data. After the maximum dimensions are obtained, the maximum dimensions may be used as in the first embodiment. If portions with maximum dimensions are known from the characteristics of the shape of the take-out head through advance observation, as a matter of course, maximum dimensions may be calculated by obtaining coordinate values from specific dot group data in a pinpoint manner without collecting data on dots at the same depth as discussed earlier.

A known measurement technique may be used to measure maximum dimensions on the basis of images. With the above example, it is possible to minimize a measurement error due to the difference in the degree of proficiency among operators. When captured image data are used, maximum dimensions can be also measured by comparing a normal image of the take-out head (attachment) and a captured image thereof to measure maximum dimensions automatically from the difference between such images, or using AI technology which is good at image recognition. As a result, measurement can be automated.

(Estimation of Normal Vector to Attachment and Normal Vector to Die)

FIG.12is a block diagram illustrating the configuration of a normal vector estimation system that is used to apply the normal vector estimation method according to the present invention to the molded product manufacturing system described above. In the block diagram inFIG.12, the same constituent elements as the constituent elements in the block diagram inFIG.5are denoted by the same reference numerals, and elements that are not necessary to estimate normal vectors are not illustrated. In the block diagram inFIG.12, the control device90includes a coordinate/depth determination section98and a normal vector computation section99, and a posture control device drive section59D configured to control the reverse unit59C as the posture control device on the basis of the result of estimating normal vectors is illustrated. At least the coordinate/depth determination section98and the normal vector computation section99of the control device90are each constituted using a processor.

The normal vector estimation system estimates a normal vector to the take-out head60as the attachment mounted to the elevating frame59B as the approach frame of the apparatus5and a normal vector to the dies31,32, and34mounted to the molding machine3. In the present embodiment, a vector that is perpendicular to the respective mating surfaces of the fixed die31and the movable die (32,34) of the die mounted to the molding machine3is defined as the normal vector to the die. In addition, a vector that is perpendicular to an imaginary plane that extends in a direction in which the elevating frame59B as the approach frame extends and that is parallel to the mating surfaces when the take-out head60as the attachment is inserted between the fixed die31and the movable die (32,34) is defined as the normal vector to the take-out head60as the attachment.

In the present embodiment, as illustrated inFIGS.13and14A and14B, an image including mounting bolts82as three or more mounting members or the suction pads60A to60D as three or more contact members is captured using an imaging device C11(three-dimensional imaging device) capable of capturing an image including depth data or coordinate data on an object to be captured, the mounting bolts82extending in a direction (pull-out direction) that is orthogonal to the elevating frame59B as the approach frame to mount the take-out head (attachment)60to the elevating frame59B, and the suction pads60A to60D contacting the molded product. The first imaging device C11may be the imaging device C1or C2illustrated inFIGS.1to4. The first imaging device C11captures an image of the take-out head60, as the attachment, from the front or the back. Image data captured by the three-dimensional imaging device include depth data on the object to be captured.

As illustrated inFIG.14A, the four mounting bolts82which are seen on the back surface of the take-out head60serve as the reference for mounting of the take-out head. Thus, an imaginary plane PS1formed by connecting the four mounting bolts82and extending orthogonally to the four mounting bolts82is orthogonal to the normal vector to the take-out head60. As illustrated inFIG.14B, in addition, an imaginary plane PS2formed by connecting the centers of the suction pads60A to60D and extending orthogonally to the suction pads60A to60D is orthogonal to the normal vector to the take-out head60. InFIGS.14A and14B, and15, VD denotes a normal vector in the pull-out direction, and VH denotes a normal vector in the up-down direction. The normal vector to the take-out head60is estimated through computation using the coordinate/depth determination section98and the normal vector computation section99on the basis of depth data or coordinate data on three of the mounting bolts82or three of the suction pads obtained from the image. The coordinate/depth determination section98acquires depth data or coordinate data on the four mounting bolts82or the four suction pads60A to60D from information (data stored in the data storage section92) obtained from an image captured by the three-dimensional imaging device which is used as the imaging device C11. As a matter of course, these data match the specifications of the three-dimensional imaging device being used. In the present embodiment, the mounting members are the mounting bolts82. However, the mounting members may include a mounting plate81. If the mounting members include amounting fitting (mounting plate), a plurality of edge surfaces81A of the mounting fitting may be considered as three or more mounting members.

The normal vector computation section99, which is configured to include a processor, computes a normal vector according to a known method of computing a normal vector from a plane in a space.FIG.15Aillustrates the relationship between depth data and coordinate data. InFIG.15A, a point O corresponds to the position of the three-dimensional imaging device, and a point P corresponds to a certain point on the front surface or the back surface of the take-out head, for example. In this case, the depth data refer to information on the direction (specified by angles θ and φ) of the take-out head as seen from the three-dimensional imaging device and a distance r when the point P on the take-out head is seen from the three-dimensional imaging device. The coordinate data x, y, z of the point P can be represented as x=rsin θ cos φ, y=rsin θ sin φ, and z=rcos θ.

Thus, as illustrated inFIG.15B, when coordinate data on three points P, Q, and R on the front surface of the take-out head are defined as P (x1, y1, z1), Q (x2, y2, z2), and R (x3, y3, z3), for example, the coordinate data x, y, and z on the three points can be calculated by substituting depth data P (r1, φ1, θ1), Q (r2, φ2, θ2), and R (r3, φ3, θ3), on the points P, Q, and R, which are obtained by the three-dimensional imaging device, into the above formulas [x=rsin θ cos φ, y=rsin θ sin φ, z=rcos θ]. When a plane in the xyz orthogonal coordinate space is given by a plane equation Ax+By+Cz+D=0 where A, B, C, and D are each a real number, a normal vector n to the front surface of the take-out head is defined as n=(A, B, C), and thus A, B, and C can be obtained by substituting the coordinate data on P, Q, and R into the plane equation and solve the simultaneous equations.FIG.16illustrates a flow of this conversion and computation.

In another method of calculating a normal vector, a normal vector a is represented by a formula a=Ai+Bj+Ck, where i, j, and k are base vectors along the x-axis, the y-axis, and the z-axis, respectively. A unit normal vector n with a magnitude of 1 is calculated using a formula n=(Ai+Bj+Ck)/(A2+B2+C2)1/2. A normal vector to the imaginary plane PS1or PS2may be calculated using this computation method. As a matter of course, other computation methods may also be used. The above computation is executed by the normal vector computation section99.

In the present embodiment, to calculate a normal vector to the die, an image including a surrounding component located around the mating surface of the fixed die31or the mating surface of the movable die (32,24) is captured using the second imaging device C12(three-dimensional imaging device) capable of capturing an image including depth data or coordinate data. The second imaging device C12may be at least one of the imaging devices C2to C8, which are provided with an adjustable field angle and located as illustrated inFIGS.1to4. In the present embodiment, three or more extending portions (see the guide pins36A to36D of the die, edge surfaces34A of the fixed die31or the movable die34, tie bars35A to35D, etc. inFIGS.17and18) are specified from the image captured by the second imaging device as the three-dimensional imaging device, the extending portions being each a part of the fixed die31or the movable die (32,34) or apart of the surrounding component and extending in a direction that coincides with the open/close direction (pull-out direction) for the fixed die31and the movable die (32,34). The extending portions can be specified from an image displayed on the display73of the image display device72. As discussed earlier, image data captured by the three-dimensional imaging device and stored in the data storage section92include depth data and coordinate data on the object to be captured, and thus the coordinate/depth determination section98determines depth data or coordinate data on the specified three or more extending portions. Then, the normal vector computation section99estimates a normal vector to the die through computation on the basis of the depth data or the coordinate data determined by the coordinate/depth determination section98.

In the example inFIG.17, depth data or coordinate data on the four guide pins36A to36D or tie bars35A to35D are acquired from an image, and an imaginary plane PS3or PS4which is orthogonal to the four guide pins36A to36D or tie bars35A to35D is calculated on the basis of such data. The guide pins36A to36D or the tie bars35A to35D are extending portions that are not varied when attaching the die, and a mating surface of the die which is mounted using the guide pins36A to36D or the tie bars35A to35D is substantially parallel to the three-dimensional imaginary plane PS3or PS4which is calculated using the coordinate data or the depth data on the guide pins36A to36D or the tie bars35A to35D. Thus, a normal vector to the die, namely, a normal vector VD in the pull-out direction and a normal vector VH in the up-down direction, can be calculated in this manner using the computation formula discussed earlier.

In the example inFIG.18, a three-dimensional imaging device is mounted at the position of the imaging device C5illustrated inFIG.1, and caused to approach the die to acquire three-dimensional image data including four intersections of the edge surfaces34A (four edges surrounding the mating surface of the die) of the movable die34. A three-dimensional imaginary plane PS5including the four intersections is calculated from the coordinate data or the depth data on the four intersections obtained together with the image data. The mating surface of the die is substantially parallel to the three-dimensional imaginary plane PS5. A normal vector VD in the pull-out direction and a normal vector VH in the up-down direction can be calculated from such data. In this example, a normal vector is calculated from information on portions related to the mating surface of the die, and therefore a normal vector which may be varied according to the mounting state of the die can be accurately estimated.

(Possibility of Use and Teaching)

The maximum dimensions measured as described above and the normal vectors may be used as desired. In the embodiment described above, the possibility-of-use determination section93determines, on the basis of information on the three-dimensional geometry of the take-out head60, whether or not the take-out head60is appropriate for use in take-out work before teaching is performed by operating the teaching section91, and outputs an alarm if the take-out head60is not usable. That is, it can be determined, on the basis of the maximum dimensions, whether or not the take-out head60can approach the die, which is open, without colliding with the die, and it can be determined, on the basis of the degree of inconsistency between the normal vector to the take-out head and the normal vector to the die, whether or not the molded product can be definitely taken out using the take-out head. That is, it is determined beforehand whether the take-out head60possibly collides with a surrounding object while moving, or whether the molded product cannot be definitely taken out, when teaching is executed, and an alarm is issued if there is no possibility of use of the take-out head60.

If there is a problem with the mounting posture of the take-out head60, the take-out head60may be mounted again on the basis of the alarm, or the posture of the take-out head60may be changed to an adequate posture by causing the reverse unit59C as the posture control device to operate by providing a command to the posture control device drive section59D.

INDUSTRIAL APPLICABILITY

With the present invention, image data including depth data or coordinate data obtained from the die and the attachment to be actually mounted are sampled by the imaging device to estimate a normal vector to the attachment and a normal vector to the die. Thus, normal vectors closely related to the actual mounting state of the die and the attachment can be estimated. Thus, it is possible to easily implement automation of teaching, control for the posture of the attachment, etc.