Projection device, projection method, and measurement device

Abstract

The present invention provides a projection device, a projection method, and a measurement device that are for assisting measurements performed by a three-dimensional measurement machine. This projection method comprises: a step for acquiring a transformation matrix for performing coordinate transformation from a coordinate system of a measurement device (10) to a coordinate system of a projection device (50); a step for using the transformation matrix to perform coordinate transformation to the coordinate system of the projection device with respect to a measurement assistance image in which the shape of a measurement target area of a workpiece that has been installed in the measurement device is indicated by the coordinate system of the measurement device; and a step for projecting the coordinate-transformed measurement assistance image onto the workpiece.

Description

Projection device, projection method, and measuring device

[0001] The present invention relates to a projection device, a projection method, and a measuring device, and more particularly to a projection device, a projection method, and a measuring device used for measuring objects (hereinafter referred to as "workpieces"), etc.

[0002] A coordinate measuring machine (CMM) measures the three-dimensional shape of a workpiece by moving a probe relative to the workpiece. The measurement data obtained from the workpiece measurement is calculated based on pre-set measurement coordinates to determine the three-dimensional shape of the workpiece.

[0003] Patent Document 1 discloses a method for setting measurement coordinates in a three-dimensional coordinate measuring machine. In the three-dimensional coordinate measuring machine described in Patent Document 1, measurement coordinates are automatically set based on measurement data obtained by measuring a plane and a hole.

[0004] Japanese Unexamined Patent Publication No. 7-128044

[0005] When performing measurements using a three-dimensional measuring machine, the operator must know in advance the positional reference point for the workpiece placed on the surface plate. If the operator is not proficient in measuring the workpiece's reference point, they may make mistakes in the workpiece's placement or orientation, leading to rework. Furthermore, if the workpiece's reference point is misidentified during manual alignment, the risk of accidents such as collisions between the measuring device and the workpiece increases when performing CNC (Computer Numerical Control) measurement.

[0006] To address the above issues, it is conceivable to regulate the workpiece placement using a workpiece placement jig. By using a workpiece placement jig to place the workpiece, the reproducibility of the workpiece's placement position and orientation can be ensured, thereby preventing rework and reducing the risks associated with the above-mentioned issues.

[0007] However, when using a jig for workpiece placement, it is necessary to fix the jig to the three-dimensional measuring machine. Furthermore, a dedicated jig must be prepared for each workpiece. This results in the disadvantage of losing the versatility of the three-dimensional measuring machine.

[0008] This invention has been made in view of these circumstances, and aims to provide a projection device, a projection method, and a measuring device for supporting measurements by a three-dimensional measuring machine.

[0009] A projection device according to a first aspect of the present invention comprises: a first calculation unit that acquires a transformation matrix for transforming coordinates from the coordinate system of a measuring device to the coordinate system of a projection device; a second calculation unit that uses the transformation matrix to perform a coordinate transformation on a measurement support image that shows the shape of a part of a workpiece to be measured in the coordinate system of a measuring device, to the coordinate system of a projection device; and a projection unit that projects the coordinate-transformed measurement support image onto the workpiece.

[0010] A projection device according to a second aspect of the present invention, in the first aspect, includes a detection unit that detects irradiation light irradiated onto a probe provided in a measuring device, and a first calculation unit determines the coordinates of the projection point of the irradiation light on a screen located at a distance equal to the focal length of the projection unit from the projection unit, based on the irradiation light detected by the detection unit, and calculates a transformation matrix based on the coordinates of the projection point.

[0011] In the projection device according to the third aspect of the present invention, in the second aspect, the detection unit detects the reflected light of the irradiation light reflected by the measuring probe.

[0012] In the projection device according to the fourth aspect of the present invention, in the second aspect, the detection unit detects fluorescence generated when a measuring element is excited by the irradiated light.

[0013] In the projection device according to the fifth aspect of the present invention, in the second aspect, the detection unit is attached to a probe and directly detects the irradiated light.

[0014] In the projection apparatus according to the sixth aspect of the present invention, in the second aspect, the first calculation unit determines the coordinates of the projection points of the irradiated light on the screen by performing a raster scan of the irradiated light on the screen.

[0015] In the seventh aspect of the present invention, in the second embodiment, the projection unit projects an encoded image onto a screen in which regions with different brightness levels are arranged along the axis direction of the coordinate system on the screen, and the first calculation unit determines the coordinates of the projection point of the irradiated light on the screen based on the image signal obtained by detecting the encoded image with the detection unit.

[0016] In the projection apparatus according to the eighth aspect of the present invention, in the second aspect, the projection unit projects a phase-shifted image of a luminance distribution with different phases along the axis direction of the coordinate system on the screen onto the screen, and the first calculation unit determines the coordinates of the projection point of the irradiated light on the screen based on the image signal obtained by detecting the phase-shifted image with the detection unit.

[0017] A measuring device according to the ninth aspect of the present invention comprises a projection device according to any of the first to eighth aspects, and a measuring control unit that controls the measurement of a workpiece on which a measurement support image has been projected from the projection device.

[0018] A projection method according to a tenth aspect of the present invention includes the steps of: obtaining a transformation matrix for transforming coordinates from the coordinate system of a measuring device to the coordinate system of a projection device; using the transformation matrix, performing a coordinate transformation on a measurement support image that shows the shape of a part to be measured on a workpiece installed on the measuring device in the coordinate system of the measuring device, to the coordinate system of the projection device; and projecting the transformed measurement support image onto the workpiece.

[0019] According to the present invention, a measurement support image can be projected onto the workpiece to assist in measurement, allowing the operator to easily confirm the installation position and orientation of the workpiece.

[0020] This is a diagram (perspective view and block diagram) showing a three-dimensional measuring machine according to one embodiment of the present invention. This is an explanatory diagram for explaining the projector model. This is an explanatory diagram for explaining the measurement procedure (a1). This is an explanatory diagram for explaining the measurement procedure (a2). This is an explanatory diagram for explaining the measurement procedure (a3). This is an explanatory diagram for explaining the measurement procedure (a3). This is an explanatory diagram for explaining the measurement procedure (b1). This is an explanatory diagram for explaining the measurement procedure (b2). This is an explanatory diagram for explaining the measurement procedure (b3).

[0021] Embodiments of the present invention will be described below with reference to the attached drawings.

[0022] [Three-Dimensional Measuring Machine] Figure 1 is a diagram (perspective view and block diagram) showing a three-dimensional measuring machine according to one embodiment of the present invention.

[0023] As shown in Figure 1, the three-dimensional measuring machine 1 according to this embodiment includes a measuring device 10, a projection device 50, and a control device 100.

[0024] The measuring device 10 is a device (CMM) that measures the shape (contour) and dimensions of a workpiece W by bringing a measuring element 26, which is provided at the tip of a probe 22 (including a stylus 24), into contact with the workpiece W and scanning it.

[0025] The control device 100 controls the measuring device 10 to control the measurement of the workpiece W by the measuring device 10. The control device 100 receives operation input from the operator via the operation unit 110 and outputs commands to the measuring device 10 according to the operation input.

[0026] The projection device (projector) 50 is equipped with a light source 52 (for example, an LED (Light-Emitting Diode) light source or a laser light source) and a projection optical system 54, and projects an image (measurement support image) to support measurement onto the workpiece W placed on the surface plate 18 of the measuring device 10. The measurement support image is an image corresponding to the shape of the part to be measured on the workpiece W, and is in the CMM coordinate system Σ of the measuring device 10. Ｗ Based on this, each measurement target location is defined. Such measurement support images can be generated, for example, based on the CAD (Computer Aided Design) data of the workpiece W. For example, the measurement support images are pre-stored in the memory 104 of the control device 100 for each workpiece W. The operator can retrieve the measurement support image corresponding to the workpiece W by giving an instruction to the processing unit 102 via the operation unit 110 to specify the workpiece W to be used for measurement. Here, the projection device 50 is an example of a projection unit according to the present invention.

[0027] As an image projection method in the projection device 50, for example, projection mapping can be employed. Here, projection mapping refers to projecting an image onto the workpiece W that corresponds to the shape of the workpiece W. In the projection mapping according to this embodiment, for example, an image corresponding to the properties of the surface (e.g., flat or curved surface or inclination angle or curvature with respect to the surface plate 18, etc.) is projected onto the surface of the workpiece W, and an image corresponding to the properties of the structure is projected onto structures formed on the workpiece W (e.g., holes, protrusions or steps). More specifically, for holes, if it is difficult to illuminate the inner wall of the hole, an image showing the outline of the hole, etc., is projected. For protrusions and steps, an image showing their respective properties (e.g., shape, outline or dimensions, etc.) is projected. In addition to projection mapping, laser mapping may be employed as an image projection method, for example.

[0028] According to this embodiment, the projection device 50 can project an image onto the workpiece W to assist in measurement, allowing the operator to easily confirm the installation position and orientation of the workpiece W. This helps to prevent errors caused by misrecognition of the installation position or orientation of the workpiece W.

[0029] Furthermore, the projection device 50 is not limited to a single unit; multiple projection devices 50 may be installed to project images onto the workpiece W from multiple directions. Also, in the example shown in Figure 1, the projection device 50 is mounted on a tripod, separate from the measuring device 10, but the installation configuration of the projection device 50 is not limited to this. The projection device 50 may be installed, for example, on the ceiling, wall, or floor of the installation location of the measuring device 10, or it may be attached to the measuring device 10 (such as the surface plate 18).

[0030] (Measuring device) As shown in Figure 1, the measuring device 10 includes a base 20 and a surface plate 18 provided on the base 20. The surface 18A of the surface plate 18 is formed in a planar shape. The workpiece W is placed on the surface 18A of the surface plate 18. The workpiece W may be fixed to the surface 18A of the surface plate 18 using, for example, a clamping mechanism.

[0031] A pair of columns 16 are attached to the surface plate 18, extending upward from the surface 18A of the surface plate 18 in the figure. A beam 14 is spanned across the upper ends of the columns 16. The pair of columns 16 are movable synchronously on the surface plate 18, and the beam 14 is movable parallel to the surface 18A of the surface plate 18. A motor can be used as a driving means for moving the columns 16 relative to the surface plate 18. The pair of columns 16 may also be connected on the underside of the surface plate 18.

[0032] A head 12 is attached to the beam 14. The head 12 is movable along the length of the beam 14. A motor can be used as a driving means for moving the head 12 relative to the beam 14.

[0033] A probe 22 is attached to the lower end of the head 12 so as to be movable in the vertical direction shown in the figure. A motor can be used as a driving means for moving the probe 22 in the vertical direction.

[0034] The measuring device 10 includes a movement measurement unit (for example, a linear encoder) for measuring the amount of movement of the column 16, the head 12, and the probe 22, respectively.

[0035] The probe 22 includes a stylus 24, which is a highly rigid axial member. The material of the stylus 24 can be, for example, a superhard alloy, titanium, stainless steel, ceramic, or carbon fiber.

[0036] A measuring element 26 (probe sphere) is provided at the tip of the stylus 24 of the probe 22. The measuring element 26 is a spherical component with high hardness and excellent wear resistance. For example, ruby, silicon nitride, zirconia, ceramic, etc. can be used as the material for the measuring element 26. The diameter of the measuring element 26 is 4.0 mm in one example.

[0037] When measuring the workpiece W, the column 16, head 12, and probe 22 are moved to bring the measuring probe 26 into contact with the workpiece W. The measuring probe 26 is then scanned along the shape of the workpiece W, and the displacement of the measuring probe 26 is measured. This measured displacement data is transmitted to the control device 100. The control device 100 processes this data using a measurement program to determine the shape (contour) and dimensions of the workpiece.

[0038] (Control device) As shown in Figure 1, the control device 100 includes a processing unit 102 and a memory 104, and is connected to the measuring device 10 and the projection device 50 via a controller 106. The control device 100 may be configured as, for example, a personal computer or a workstation.

[0039] The processing unit 102 includes a processor (e.g., a CPU (Central Processing Unit)) that controls the operation of each part of the measuring device 10 and the control device 100. The processing unit 102 receives operation input from the operator via the operation unit 110. Then, via the controller 106, the processing unit 102 transmits control signals corresponding to this operation input to each part of the measuring device 10, the projection device 50, and the control device 100 to control the operation of each part. Here, the processing unit 102 functions as a projection control unit for controlling the projection device 50 and a measurement control unit for controlling the measurement of the workpiece W. For example, the processing unit 102 receives a designation of the workpiece W to be used for measurement in response to operation input from the operation unit 110, retrieves a measurement support image corresponding to the workpiece W from the memory 104, performs the calculations described later, and projects the measurement support image using the projection device 50. In other words, the processing unit 102 is an example of a first calculation unit and a second calculation unit.

[0040] The operation unit 110 includes an operating member that receives operation input from the operator. This operating member can be, for example, a keyboard for text input, a pointing device, a mouse, or a touch panel provided on the surface of the display unit 112.

[0041] The controller 106 is a means for communicating with the measuring device 10 and performs data conversion processing between the controller 10 and the measuring device 10. The controller 106 may include a D / A (digital-to-analog) converter for converting digital commands transmitted from the control device 100 to the measuring device 10 into analog signals, and an A / D (analog-to-digital) converter for converting data such as measured values ​​sent from the measuring device 10 to the control device 100 into digital data.

[0042] The memory 104 includes a storage device that stores a program used for calculations by the processing unit 102, and data such as measurement results obtained from the measuring device 10. As the memory 104, for example, a device including a magnetic disk such as an HDD (Hard Disk Drive) or a device including flash memory such as an SSD (Solid State Drive) can be used.

[0043] The display unit 112 is a device for displaying text information, images, GUI (Graphical User Interface), etc. For example, a liquid crystal display can be used as the display unit 112. The display unit 112 may also display data such as measured values ​​acquired from the measuring device 10.

[0044] [Projection Device] In this embodiment, when measuring the workpiece W using the measuring device 10, the projection device 50 projects an image onto the workpiece W to assist the operator's operation. In order to project the image to match the workpiece W, the CMM coordinate system Σ of the measuring device 10 is used. Ｗ and the projector coordinate system Σ of the projection device 50 Ｐ It is necessary to link the two.

[0045] (Projector Model) Figure 2 is an explanatory diagram for illustrating the projector model.

[0046] As shown in Figure 2, CMM coordinate system Σ ｗ This is a coordinate system set for the measuring device 10, with the origin being O ｗ Let X be mutually orthogonal. ｗ Axis, Y ｗ axis, Z ｗIt is a three-dimensional orthogonal coordinate system with the axis as the coordinate axis. Note that the CMM coordinate system Σ ｗ In the example shown in FIG. 1, the origin O ｗ is set on the head 12, but it is not limited to this. For example, any coordinate system may be used as long as the position (three-dimensional position) in the three-dimensional space to which the measuring device 10 belongs can be specified, or it may be set at the installation position of the work W.

[0047] The projector coordinate system Σ Ｐ has the optical axis center O Ｐ of the projection optical system of the projection device 50 as the origin, and the right direction from the origin O Ｐ is the X Ｐ axis, the downward direction is the Y Ｐ axis, and the optical axis direction is the Z Ｐ axis, which is a three-dimensional orthogonal coordinate system.

[0048] The image coordinate system Σ ｓ is a two-dimensional orthogonal coordinate system (pixel coordinate system) having a U axis and a V axis in directions parallel to the X Ｐ axis and the Y Ｐ axis, respectively, with the upper left of the screen IP, which is at a distance f from the focal length of the projection optical system of the projection device 50 along the Z Ｐ axis, as the origin, starting from the origin O Ｐ of the projector coordinate system Σ Ｐ axis.

[0049] First, the coordinates (x ｗ , y ｗ [[ID=4`1]] , z ｗ ) of the point P indicating the projection target of the image by the projection device 50 in the CMM coordinate system Σ ｗ can be converted into the coordinates (x, y, z) in the projector coordinate system Σ Ｐ using the rotation matrix R and the translation vector t of the projection device 50 as shown in the following formula (1).

[0050]

[0051] Here, [R|t] is a transformation matrix (external parameter matrix) for coordinate transformation from the CMM coordinate system Σ ｗ to the projector coordinate system Σ Ｐ [ and represents the posture and position of the projection device 50 in the CMM coordinate system Σ ｗ The components r of [R|t]１１ ,r １２ , ..., r ３３ ,t ｘ ,t ｙ ,t ｚ These are called external parameters of the projection device 50.

[0052] Next, the projector coordinate system Σ Ｐ If point P, located at (x, y, z) as viewed from the screen IP, has coordinates (pixel coordinates) of the projected point Q as (u, v), then the following relationships shown in equations (2) to (7) hold.

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] Here, (x', y') is the projector coordinate system Σ Ｐ This represents the coordinates of the projected point obtained by projecting point P, located at (x, y, z) as viewed from the image, onto the normalized image plane (z=1). Furthermore, (x'', y'') represents the coordinates of the projected point (distorted point) obtained by projecting point P onto the normalized image plane when lens distortion of the projection optical system of the projection device 50 is taken into consideration.

[0060] Also, yf ｘ , f ｙ This indicates the focal length in the x and y directions, expressed in pixels. Also, (c ｘ , c ｙ ) is the image coordinate system Σ ｓ This indicates the optical center (the position where the optical axis of the projection device 50 intersects with the screen IP, the optical center in pixel units). Also, k １ ,k ２ ,k ３ is the radial strain coefficient, and p １ , p ２ is the tangential distortion coefficient. In this embodiment, the focal length fｘ , f ｙ , optical center c ｘ , c ｙ This is called an internal parameter of the projection device 50, and the distortion coefficient k １ ,k ２ ,k ３ , p １ , p ２ This is called the distortion parameter of the projection device 50.

[0061] In the above projector model, CMM coordinate system Σ Ｗ Coordinates (x) ｗ , y ｗ , z ｗ By obtaining a pair (set) of the pixel coordinates (u, v) of the projection device 50, the CMM coordinate system Σ Ｗ and projector coordinate system Σ Ｐ A transformation matrix [R|t] (corresponding to the external parameters of the projection device 50) that links them can be calculated.

[0062] (Measurement Procedure) As described above, in order to calculate the transformation matrix [R|t], first, the CMM coordinate system Σ Ｗ Coordinates (x) ｗｊ , y ｗｊ , z ｗｊ ) and the pixel coordinates (u ｊ ,v ｊ A set of ) is obtained for at least N of the external parameters of the projection device 50. Here, j is an integer, and 1 ≤ j ≤ M and M ≥ N. CMM coordinate system Σ Ｗ Coordinates (x) ｗｊ , y ｗｊ , z ｗｊ ) and the pixel coordinates (u ｊ ,v ｊ To obtain the set of ) and realize the projection method according to this embodiment, the following two steps are performed: (a) a step of detecting that light from the projection device 50 is hitting the probe 22; (b) a step of determining which screen coordinates the light hitting the probe 22 corresponds to.

[0063] (a) The following methods (a1) to (a3) ​​can be used as the step of detecting that light from the projection device 50 has hit the probe 22.

[0064] (a1) Scattering Method In this method, as shown in Figure 3, a certain screen coordinate (u ｊ ,v ｊ ) Irradiated light (light rays L ｊ The projection device 50 outputs the reflected light R from the projection device 50 toward the measuring probe 26. The reflected light R reflected by the measuring probe 26 ｊ This is directly detected using a photodetector PD (detection unit). This allows a certain screen coordinate (u ｊ ,v ｊ ) Light ray L ｊ It is possible to detect when the sensor is incident on the measuring probe 26.

[0065] Note that the measuring probe 26 for CMM is normally small in surface roughness, and the light beam L ｊ The reflectivity of the surface has a high angular dependence on the angle of incidence. Therefore, it is preferable to avoid detecting reflected light (disturbing light) from other components. For example, the light ray L ｊ The wavelength is restricted, and the reflected light R is detected by the photodetector PD. ｊ The wavelength may be limited by a filter or the like.

[0066] (a2) Fluorescence-based methods For example, the ruby ​​used as the probe 26 for CMM is excited by light at 405 nm, 445 nm, and 514 nm and emits fluorescence at 694.3 nm and 692.8 nm.

[0067] In this method, focusing on the above properties, the light ray L is output from the projection device 50 toward the measuring probe 26. ｊ As such, light containing wavelengths of 405 nm, 445 nm, or 514 nm is used. Also, as shown in Figure 4, a filter F that transmits light with a wavelength of 694.3 nm or 692.8 nm but does not transmit ambient light (for example, a filter that transmits only red light) is placed between the photodetector PD and the measuring element 26. This allows the measuring element 26 to detect the light ray L ｊ Fluorescence FL produced by excitation by ｊ Because it can selectively detect these disturbances, the effects of external disturbances can be suppressed.

[0068] (a3) Method of Using a Photodetector PD Instead of the Probe 26 In this method, as shown in FIG. 5, a photodetector PD is attached to the stylus 24 instead of the probe 26, and the light beam L from the projection device 50 ｊ is detected. According to this method, since the light beam L from the projection device 50 ｊ directly enters the photodetector PD, highly sensitive detection becomes possible.

[0069] However, although the measuring device 10 can output the scanning position of the probe 22 (specifically, the center coordinates of the probe 26), it cannot directly output the position of the photodetector PD. Therefore, a special device is required to obtain the position of the photodetector PD from the center coordinates of the probe 26 output by the measuring device 10.

[0070] For example, as shown in FIG. 6, cameras C1 and C2 for photographing the probe 22 from two directions are installed. Note that the number of cameras C1 and C2 is not limited to two.

[0071] Next, photographing is performed with the cameras C1 and C2 in a state where the probe 26 is attached to the probe 22, and the position P1 of the probe 26 is detected from the photographed image. Then, when photographing is performed with the cameras C1 and C2, the center coordinates (position P1) of the probe 26 output from the measuring device 10 are stored in the memory 104.

[0072] Next, while photographing with the cameras C1 and C2 in a state where the photodetector PD is attached to the probe 22, the probe 22 is moved. Then, when the position of the photodetector PD detected from the photographed image coincides with the position P1, the center coordinates (position P2) of the probe 26 output from the measuring device 10 are stored in the memory 104.

[0073] Since the vector c with the position P1 as the starting point and the position P2 as the ending point is the difference between the coordinates output by the measuring device 10 and the coordinates of the photodetector PD, this is stored in the memory 104 as a correction value. The coordinates of the photodetector PD can be obtained by subtracting the correction value c from the coordinates output by the measuring device 10.

[0074] (b) As a step to determine which screen coordinates the light hitting probe 22 corresponds to, the following methods (b1) to (b3) can be used.

[0075] (b1) Method using raster scanning In this method, as shown in Figure 7, a point with different brightness is scanned within the screen IP, and the screen coordinates (u) of the point when the brightness of the photodetector PD changes are determined. ｊ ,v ｊ The coordinates output by the measuring device 10 at that time are detected as screen coordinates corresponding to the coordinates. This method requires projection for the number of pixels corresponding to the screen IP. The scanning pattern related to this method may be stored in advance in a projection control program in memory 104, for example.

[0076] (b2) Method using spatial codes In this method, as shown in Figure 8, the projection device 50 projects multiple encoded images CD. In the example shown in Figure 8, six types of images are shown as examples of encoded images CD. The three encoded images in the upper row of Figure 8 are images in which regions with different brightness levels are arranged in the U direction, and the positions of the boundaries where the brightness changes are different from each other. On the other hand, the three encoded images in the lower row are images in which regions with different brightness levels are arranged in the V direction, and the positions of the boundaries where the brightness changes are different from each other. When such encoded images are detected by the photodetector PD, an image signal is obtained in which the brightness changes at the pixels of the brightness boundaries in the encoded image CD. The photodetector PD outputs a code corresponding to the screen coordinates. By decoding this, the screen coordinates u corresponding to the brightness boundaries in the encoded image CD are obtained. ｊ and v ｊ These can be obtained individually.

[0077] The encoded image CD related to this method may be stored in advance, for example, in a projection control program in memory 104.

[0078] (b3) Phase Shift Method In this method, the projection device 50 projects a phase shift image SC having a sinusoidal luminance distribution with different phases in the horizontal or vertical direction (U direction or V direction). Then, the phase is obtained from the luminance detected by the photo detector PD and converted into screen coordinates.

[0079] In the example shown in FIG. 9, six types of images are shown as examples of the phase shift image SC. The three images in the upper row of FIG. 9 are images having a sinusoidal luminance distribution in the U direction and different phases from each other, and the three images in the lower row are images having a sinusoidal luminance distribution in the V direction and different phases from each other. When such images are detected by the photo detector PD, as shown in the graph of FIG. 9 using the symbols IL1 to IL3, an image signal in which the luminance changes sinusoidally for each pixel in the U direction or V direction is obtained. In the phase shift method, the phase for each pixel is detected from this luminance, and the phase and the screen coordinates can be associated one-to-one (see, for example, Japanese Patent No. 7526540).

[0080] The image SC according to this method may be stored in advance, for example, in the projection control program in the memory 104.

[0081] In FIGS. 8 and 9 (methods (b2) and (b3)), an example in which the photo detector PD is used instead of the measuring unit 26 described as the method (a3) is shown, but it is also possible to combine it with the method (a1) or (a2).

[0082] (Calculation of Transformation Matrix) When calculating the transformation matrix [R|t], first, the coordinates (x Ｗ , y ｗｊ , z ｗｊ ) in the CMM coordinate system Σ ｗｊ and the pixel coordinates (u ｊ , v ｊ ) of the projection device 50 are obtained at least by the number N of the external parameters of the projection device 50. Here, j is an integer, and 1 ≤ j ≤ M and M ≥ N.

[0083] Next, the error function E ｐｏｓｅ is defined as in Equation (8).

[0084]

[0085] Here, m ｊ = [u ｊ ,v ｊ ] Ｔ : The j-th screen coordinate of the projection device 50, out of the set of the three-dimensional coordinates of the measuring device 10 and the screen coordinates of the projection device 50, M ｊ = [x ｗｊ , y ｗｊ , z ｗｊ ] Ｔ : The j-th 3D coordinate of the measuring device 10 in the set of the 3D coordinates of the measuring device 10 and the screen coordinates of the projection device 50, A = [f ｘ , f ｙ , c ｘ , c ｙ ] Ｔ : Focal length of projection device 50 and central coordinate of screen, d = [k １ ,k ２ ,k ３ ,k ４ , p １ , p ２ ] Ｔ : This is the distortion parameter of the projection device 50.

[0086] The error function E defined by equation (8) ｐｏｓｅ This is an error function that shows the correspondence between the projection point Q on the screen IP and the point P on the projection target. In these correspondences, the error function E occurs when the points are in a projection relationship with each other. ｐｏｓｅ It takes its minimum value. Therefore, the error function E ｐｏｓｅ By performing nonlinear optimization to minimize the CMM coordinate system Σ Ｗ From the projector coordinate system Σ Ｐ The transformation matrix [R|t] can be calculated.

[0087] The processing unit 102, based on the measurement results in the above measurement procedures (a) to (b), calculates the CMM coordinate system Σ Ｗ From the projector coordinate system Σ Ｐ The transformation matrix [R|t] to is calculated. When measuring the workpiece W, the processing unit 102 calculates the CMM coordinate system Σ ＷThe measurement support image of the workpiece W based on this is retrieved from memory 104, and the projector coordinate system Σ is created using the transformation matrix [R|t]. Ｐ It converts to a measurement support image based on the projector coordinate system Σ. Then, the processing unit 102 converts to the projector coordinate system Σ. Ｐ A measurement support image based on this is output to the projection device 50, and the measurement support image is projected onto the workpiece W on the measuring device 10.

[0088] According to this embodiment, CMM coordinate system Σ Ｗ From the projector coordinate system Σ Ｐ By determining the transformation matrix [R|t] to the CMM coordinate system Σ of the measuring device 10, Ｗ and the projector coordinate system Σ of the projection device 50 Ｐ This allows the two to be linked. As a result, the projection device 50 can appropriately project an image corresponding to the shape of the workpiece W onto the workpiece W.

[0089] 1...3D measuring machine, 10...measuring device, 12...head, 14...beam, 16...column, 18...surface plate, 18A...surface of surface plate 18, 20...base, 22...probe, 24...stylus, 26...measuring element, 50...projection device, 52...light source, 54...projection optical system, 100...control device, 102...processing unit, 104...memory, 106...controller, 110...operating unit, 112...display unit, PD...photodetector, C1, C2...camera

Claims

1. A projection device comprising: a first calculation unit that obtains a transformation matrix for transforming coordinates from the coordinate system of a measuring device to the coordinate system of a projection device; a second calculation unit that uses the transformation matrix to perform a coordinate transformation on a measurement support image that shows the shape of the part to be measured of a workpiece installed on the measuring device in the coordinate system of the measuring device, to the coordinate system of the projection device; and a projection unit that projects the measurement support image, after the coordinate transformation, onto the workpiece.

2. The projection device according to claim 1, further comprising a detection unit for detecting irradiation light irradiated onto a probe provided in the measuring device, wherein the first calculation unit determines the coordinates of the projection point of the irradiation light on a screen located at a distance equal to the focal length of the projection unit from the projection unit, and calculates the transformation matrix based on the coordinates of the projection point.

3. The projection apparatus according to claim 2, wherein the detection unit detects the reflected light of the irradiation light reflected by the measuring probe.

4. The projection apparatus according to claim 2, wherein the detection unit detects fluorescence generated when the measuring element is excited by the irradiated light.

5. The projection apparatus according to claim 2, wherein the detection unit is attached to the probe and directly detects the irradiated light.

6. The projection apparatus according to claim 2, wherein the first calculation unit determines the coordinates of the projection points of the irradiated light on the screen by performing a raster scan of the irradiated light on the screen.

7. The projection device according to claim 2, wherein the projection unit projects an encoded image onto the screen in which regions with different brightness levels are arranged along the axis direction of the coordinate system on the screen, and the first calculation unit determines the coordinates of the projection point of the irradiated light on the screen based on the image signal obtained by detecting the encoded image by the detection unit.

8. The projection device according to claim 2, wherein the projection unit projects a phase-shifted image of a luminance distribution with different phases along the axis direction of the coordinate system on the screen onto the screen, and the first calculation unit determines the coordinates of the projection point of the irradiated light on the screen based on the image signal obtained by detecting the phase-shifted image by the detection unit.

9. A measuring device comprising: a projection device according to any one of claims 1 to 8; and a measurement control unit for controlling the measurement of the workpiece on which the measurement support image is projected from the projection device.

10. A projection method comprising: obtaining a transformation matrix for transforming coordinates from the coordinate system of a measuring device to the coordinate system of a projection device; using the transformation matrix, performing a coordinate transformation on a measurement support image that shows the shape of a part to be measured on a workpiece installed on the measuring device in the coordinate system of the measuring device, to the coordinate system of the projection device; and projecting the measurement support image, which has undergone the coordinate transformation, onto the workpiece.

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