Patent Description:
In the above technical field, document <CIT> discloses a technique of calculating a deviation amount by comparing the position of a feature point of a work detected from an image captured by an image capturer and a reference point image position and creating a correction amount for setting the deviation amount to zero.

However, in the technique described in the above literature, it is impossible to measure the relative motion between a tool attacher and a work attacher.

Document <CIT> discloses a linear axis geometric error detecting method of a five-axis numerically-controlled machine tool. The detecting method comprises the following steps that a three-eye measuring unit is set up through three high-resolution cameras, and three self-luminous characteristic target sphere images fixed to a working table and making rectilinear motion along with the X axis or the Y axis of the machine tool are collected; and through combination of camera calibrating, characteristic point position information extracting and measured information of the three cameras, a three-dimensional coordinate of the sphere center of a characteristic target sphere is obtained, and the X and Y axis linear axis geometric errors of the machine tool are measured.

It is an object of the present invention to provide a technique of solving the above-described problem.

This object is achieved by a measuring apparatus according to claim <NUM>. Advantageous further developments are as set forth in the dependent claims.

One example aspect provides a measuring apparatus for measuring a planar relative motion between a tool attacher and a work attacher of a machine tool, comprising:.

According to the present invention, it is possible to measure the relative motion between a tool attacher and a work attacher.

Example embodiments of the present invention will now be described in detail with reference to the drawings. It should be noted that the relative arrangement of the components, the numerical expressions and numerical values set forth in these example embodiments do not limit the scope of the present invention unless it is specifically stated otherwise.

A measuring apparatus <NUM> according to the first example embodiment of the present invention will be described with reference to <FIG>. The measuring apparatus <NUM> is an apparatus that measures the planar relative motion between a tool attacher <NUM> and a work attacher <NUM> of a machine tool <NUM>.

As shown in <FIG>, the measuring apparatus <NUM> includes an image capturer <NUM>, an image capturing controller <NUM>, and a calculator <NUM>. The image capturer <NUM> includes at least one image capturing element capable of performing image capturing at a first position <NUM>, a second position <NUM>, and a third position <NUM>, which are not located on the same line, in a state in which the image capturer <NUM> is attached to the tool attacher <NUM> or the work attacher <NUM>. Any one of the first position <NUM>, the second position <NUM>, and the third position <NUM> is not located on a line that passes through the remaining two.

The image capturing controller <NUM> causes the image capturing elements at the first position <NUM>, the second position <NUM>, and the third position <NUM> to capture a first point <NUM>, a second point <NUM>, and a third point <NUM>, respectively, arranged on at least one plane of an XY-plane, an XZ-plane, and a YZ-plane without changing the relative position of the tool attacher <NUM> or the work attacher <NUM> to which the image capturer <NUM> is attached. The image capturing controller <NUM> changes the relative position of the tool attacher <NUM> or the work attacher <NUM>, causes the image capturing element at the second position <NUM> and the image capturing element at the third position <NUM> to capture the first point <NUM>, causes the image capturing element at the first position <NUM> and the image capturing element at the third position <NUM> to capture the second point <NUM>, and causes the image capturing element at the first position <NUM> and the image capturing element at the second position <NUM> to capture the third point <NUM>. Based on the image capturing result of the image capturer <NUM>, the calculator <NUM> calculates a value indicating the planar relative motion between the tool attacher <NUM> and the work attacher <NUM>.

According to this example embodiment, since an image capturing element captures a point on a plane at each of the first position, the second position, and the third position, any one of which is not located on a line that passes through the remaining two, the planar relative motion between the tool attacher and the work attacher can accurately be measured.

A measuring apparatus according to the second example embodiment of the present invention will be described next with reference to <FIG>. <FIG> is a view for explaining the outline of the measuring apparatus according to this example embodiment. A measuring apparatus <NUM> measures the planar relative motion between a tool attacher <NUM> and a work attacher <NUM> of a machine tool <NUM>. The measuring apparatus <NUM> includes an image capturer <NUM>. Based on the image capturing result of the image capturer <NUM>, the measuring apparatus <NUM> calculates a value indicating the planar relative motion between the tool attacher <NUM> and the work attacher <NUM>. Note that <FIG> shows an example in which a transparent glass plate <NUM> is arranged on the work attacher <NUM>. Grid lines (not shown) are drawn on the glass plate <NUM>. The measuring apparatus <NUM> causes the image capturer <NUM> to capture a predetermined position, for example, a grid point on the glass plate <NUM>, thereby measuring the relative motion.

<FIG> is a block diagram for explaining the configuration of the measuring apparatus <NUM> according to this example embodiment. The measuring apparatus <NUM> includes the image capturer <NUM>, an image capturing controller <NUM>, and a calculator <NUM>. The image capturer <NUM> includes at least one image capturing element capable of performing image capturing at a first position, a second position, and a third position, which are not located on the same line in a state in which the image capturer <NUM> is attached to the tool attacher <NUM> or the work attacher <NUM>. Note that an example in which the image capturer <NUM> is attached to the tool attacher <NUM> is shown here. The image capturer <NUM> includes three cameras <NUM>, <NUM>, and <NUM> as the at least one image capturing element. In the measuring apparatus <NUM>, the image capturer <NUM>, the image capturing controller <NUM>, and the calculator <NUM> form one unit. Even the existing machine tool <NUM> can use the measuring apparatus <NUM> when the measuring apparatus <NUM> according to this example embodiment is attached to the machine tool <NUM>. Also, the measuring apparatus <NUM> may be incorporated in the machine tool <NUM> in advance. Note that the tool attacher(spindle) <NUM> is controlled by a spindle controller (not shown). The spindle controller controls the spindle based on a command from the image capturing controller <NUM>. The operation of the tool attacher <NUM> is controlled such that it synchronizes with the operation of the image capturer <NUM>. The description has been made here using an example in which the three cameras <NUM>, <NUM>, and <NUM> are provided as the at least one image capturing element. The number of cameras may be two or four or more.

The arrangement positions of the three cameras <NUM>, <NUM>, and <NUM> will be described here with reference to <FIG> and <FIG>. <FIG> is a perspective view, viewed from a bottom surface side, for explaining the image capturer of the measuring apparatus according to this example embodiment. <FIG> is a bottom view for explaining the image capturer of the measuring apparatus according to this example embodiment.

The three cameras <NUM>, <NUM>, and <NUM> are arranged in an L-shaped pattern. With this arrangement, as for the arrangement positions of the three cameras, any one of the three cameras is not located on a line that passes through the remaining two. For example, the camera <NUM> is arranged at the first position, the camera <NUM> is arranged at the second position, and the camera <NUM> is arranged at the third position. The cameras <NUM>, <NUM>, and <NUM> can perform image capturing at the first position, the second position, and the third position, respectively. Note that the arrangement positions of the cameras <NUM>, <NUM>, and <NUM> are not limited to the example shown here.

Here, referring to <FIG>, the cameras <NUM> and <NUM> are arranged on a line <NUM>, but the camera <NUM> is not located on the line <NUM>. The cameras <NUM> and <NUM> are arranged on a line <NUM>, but the camera <NUM> is not located on the line <NUM>. The cameras <NUM> and <NUM> are arranged on a line <NUM>, but the camera <NUM> is not located on the line <NUM>. That is, any one of the first position, the second position, and the third position is not located on a line that passes the remaining two. In <FIG>, as an example of the arrangement, the cameras <NUM> to <NUM> are arranged at the vertices of a right-angled isosceles triangle, respectively. However, the present invention is not limited to this, and, for example, one camera may be arranged at each vertex of an isosceles triangle, at each vertex of an equilateral triangle, or at each vertex of another triangle. With this arrangement, two directions, for example, an X direction and a Y direction can be created. Hence, two directions can be captured using three cameras.

The image capturing controller <NUM> first causes the camera <NUM> at the first position, the camera <NUM> at the second position, and the camera <NUM> at the third position to capture a first point <NUM>, a second point <NUM>, and a third point <NUM>, respectively, arranged on an XY-plane without changing the relative position between the tool attacher <NUM> to which the image capturer <NUM> is attached and the work attacher <NUM>. Note that the work attachment surface of the work attacher <NUM> is defined as the XY-plane.

Then, the image capturing controller <NUM> moves the tool attacher <NUM> along an arrow <NUM>, thereby changing the relative position between the tool attacher <NUM> and the work attacher <NUM>. That is, the image capturing controller <NUM> moves the tool attacher <NUM> located above the first point <NUM> to, for example, a position above the second point <NUM> along the arrow.

When the movement of the tool attacher <NUM> is completed, the image capturing controller <NUM> causes the cameras <NUM> and <NUM> to capture the first point <NUM>, causes the cameras <NUM> and <NUM> to capture the second point, and causes the cameras <NUM> and <NUM> to capture the third point. In this way, the image capturing controller <NUM> causes the cameras <NUM>, <NUM>, and <NUM> to capture the points <NUM>, <NUM>, and <NUM> while changing the position of the tool attacher <NUM>.

Based on the image capturing result of the image capturer <NUM>, the calculator <NUM> calculates a value indicating the planar relative motion between the tool attacher <NUM> and the work attacher <NUM>. That is, the three points <NUM>, <NUM>, and <NUM> of the work attacher <NUM> are captured using the three cameras <NUM>, <NUM>, and <NUM>, thereby detecting a deviation and measuring the planar relative motion between the tool attacher <NUM> and the work attacher <NUM>.

Note that although the first point <NUM>, the second point <NUM>, and the third point <NUM> are points on the work attacher <NUM> here, a grid representing the first point <NUM>, the second point <NUM>, and the third point <NUM> may be used (glass plate <NUM>). As the grid, for example, grid-shaped lines are formed by drawing a plurality of orthogonal lines on a flat plate containing transparent glass, plastic, resin, or the like, and the intersections are defined as the first point <NUM>, the second point <NUM>, the third point <NUM>, and the like. Note that the material of the grid is not limited to glass or a plastic resin, the grid is not limited to a transparent material, and the grid-shaped lines are not limited to orthogonal lines. The first point <NUM>, the second point <NUM>, and the third point <NUM> are not fixed to the illustrated points, and may change along with the movement of the tool attacher <NUM>.

Here, the planar relative motion between the tool attacher <NUM> and the work attacher <NUM> is measured by capturing the points <NUM>, <NUM>, and <NUM> on the XY-plane. However, a spatial relative motion can be measured by, for example, capturing at least two planes of the XY-plane, the XZ-plane, and the YZ-plane using the three cameras <NUM>, <NUM>, and <NUM>.

That is, based on the image capturing result on at least two planes of the XY-plane, the XZ-plane, and the YZ-plane, the calculator <NUM> calculates a value indicating the relative motion on the at least two planes of the XY-plane, the XZ-plane, and the YZ-plane between the tool attacher <NUM> and the work attacher <NUM>. This allows the measuring apparatus <NUM> to measure the spatial accuracy (pitch (rotation angle about the X-axis)/roll (rotation angle about the Y-axis)/yaw (rotation angle about the Z-axis), and the like) between the tool attacher <NUM> and the work attacher <NUM>.

According to this example embodiment, since image capturing is performed, using three cameras, at three positions any one of which is not located on a line that passes through the remaining two positions, the planar relative motion between the tool attacher and the work attacher can be measured accurately in a short time.

A measuring apparatus according to the third example embodiment of the present invention will be described next with reference to <FIG> is a view for explaining the configuration of the measuring apparatus according to this example embodiment. The measuring apparatus according to this example embodiment is different from the second example embodiment in that one camera is used. The rest of the components and operations is the same as in the second example embodiment. Hence, the same reference numerals denote the same components and operations, and a detailed description thereof will be omitted.

A measuring apparatus <NUM> includes one camera <NUM> as at least one image capturing element. The camera <NUM> can move to a first position <NUM>, a second position <NUM>, and a third position <NUM>. That is, the camera <NUM> can move to the first position <NUM>, the second position <NUM>, and the third position <NUM> by moving along the periphery of a tool attacher <NUM> of a machine tool <NUM>. An image capturing controller <NUM> controls the camera <NUM> to capture points <NUM>, <NUM>, and <NUM>.

According to this example embodiment, since image capturing is performed, using one camera, at three positions any one of which is not located on a line that passes through the remaining two positions, the planar relative motion between the tool attacher and the work attacher can be measured accurately at low cost.

A measuring apparatus according to the fourth example embodiment of the present invention will be described next with reference to <FIG> is a view for explaining the configuration of the measuring apparatus according to this example embodiment. The measuring apparatus according to this example embodiment is different from the second example embodiment in that a machine tool includes an image capturing controller and a calculator, the measuring apparatus includes a storage unit, a transmitter, and a display unit, and the measuring apparatus is located outside the machine tool. The rest of the components and operations is the same as in the second example embodiment. Hence, the same reference numerals denote the same components and operations, and a detailed description thereof will be omitted.

A measuring apparatus <NUM> includes a storage unit <NUM>, a transmitter <NUM>, and a display unit <NUM>. The storage unit <NUM> stores various measuring programs according to the types of machine tools, the types of tools, the types of works, and the like. The transmitter <NUM> transmits a measuring program to a machine tool <NUM>. The machine tool <NUM> receives, by a receiver (not shown), the measuring program transmitted from the measuring apparatus <NUM>. The measuring program is a program that describes, for example, control by the image capturing controller <NUM> of the machine tool <NUM>, and includes the image capturing timing and the image capturing position of an image capturer <NUM>, and the moving path and the moving speed of a tool attacher <NUM>. The image capturing controller <NUM> of the machine tool <NUM> performs image capturing by controlling the image capturer <NUM> and the like in accordance with the received measuring program, and the calculator <NUM> calculates a value indicating the planar relative motion between the tool attacher <NUM> and a work attacher <NUM>. The calculation result is transmitted to the measuring apparatus <NUM>. The measuring apparatus <NUM> receives the value calculated by the calculator <NUM>, and the display unit <NUM> displays the received calculated value.

According to this example embodiment, since the measuring program is transmitted to the machine tool, even if the measuring apparatus and the machine tool are different apparatuses, the planar relative motion between the tool attacher and the work attacher can be measured.

While the invention has been particularly shown and described with reference to example embodiments thereof, the invention is not limited to these example embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the defined claims. A system or apparatus including any combination of the individual features included in the respective example embodiments may be incorporated in the scope of the present invention.

Claim 1:
A measuring apparatus (<NUM>; <NUM>; <NUM>; <NUM>) for measuring a planar relative motion between a tool attacher (<NUM>; <NUM>) and a work attacher (<NUM>; <NUM>) of a machine tool (<NUM>; <NUM>; <NUM>; <NUM>), comprising:
an image capturer (<NUM>; <NUM>; <NUM>) that includes at least one image capturing element capable of performing image capturing, in the same direction, at a first position (<NUM>; <NUM>; <NUM>), a second position (<NUM>; <NUM>; <NUM>), and a third position (<NUM>; <NUM>; <NUM>), which are not located on the same line, in a state in which said image capturer (<NUM>; <NUM>; <NUM>) is attached to one of the tool attacher (<NUM>; <NUM>) and the work attacher (<NUM>; <NUM>), any one of the first position (<NUM>; <NUM>; <NUM>), the second position (<NUM>; <NUM>; <NUM>), and the third position (<NUM>; <NUM>; <NUM>) being not located on a line that passes through remaining two;
an image capturing controller (<NUM>; <NUM>) that is configured to cause the image capturing elements at the first position (<NUM>; <NUM>; <NUM>), the second position (<NUM>; <NUM>; <NUM>), and the third position (<NUM>; <NUM>; <NUM>) to capture a first point (<NUM>; <NUM>), a second point (<NUM>; <NUM>), and a third point (<NUM>; <NUM>), respectively, arranged on at least one plane of an XY-plane, an XZ-plane, and a YZ-plane without changing a relative position of one of the tool attacher (<NUM>; <NUM>) and the work attacher (<NUM>; <NUM>) to which said image capturer (<NUM>; <NUM>; <NUM>) is attached, and
to change the relative position of one of the tool attacher (<NUM>; <NUM>) and the work attacher (<NUM>; <NUM>), to cause the image capturing element at the second position (<NUM>; <NUM>; <NUM>) and the image capturing element at the third position (<NUM>; <NUM>; <NUM>) to capture the first point (<NUM>; <NUM>), to cause the image capturing element at the first position (<NUM>; <NUM>; <NUM>) and the image capturing element at the third position (<NUM>; <NUM>; <NUM>) to capture the second point (<NUM>; <NUM>), and to cause the image capturing element at the first position and the image capturing element at the second position to capture the third point (<NUM>; <NUM>); and
a calculator (<NUM>; <NUM>) that is configured to calculate a value indicating the planar relative motion between the tool attacher (<NUM>; <NUM>) and the work attacher (<NUM>; <NUM>) based on an image capturing result of said image capturer (<NUM>; <NUM>; <NUM>).