Position measuring device and position measuring method

Abstract

This position measurement device comprises: a position measurement unit which irradiates a reflective element with measuring light, receives reflected light that is reflected by the reflective element, and acquires positional information on the reflective element in the three-dimensional space; and a reference position measurement unit which irradiates at least one reference reflecting element with reference measurement light, receives reference reflected light that is reflected by the reference reflecting element, and acquires positional information on the reference reflecting element in the three-dimensional space, wherein the positional information, which pertains to the reference reflecting element and is acquired by the reference position measurement unit, is used to correct the positional information which pertains to the reflecting element and is measured by the position measurement unit.

Description

[Technical Field]

[0001] The present invention relates to a position measuring device and a position measuring method. [Background technology]

[0002] Machining and assembly processes are performed automatically using robots and machine tools. In these processes, in order to improve the accuracy of the machining and assembly, it is necessary to measure with high precision the position of the arm of the robot to be controlled and the position of the tip of the spindle of the machine tool. For example, there is known a device that measures the position of a predetermined part of a robot device using an external measuring device (Patent Document 1). In controlling a robot, it is required to measure the position of the robot with high accuracy. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2007 / 002319 Summary of the Invention

[0004] One aspect of the present invention includes a reference position measurement unit that irradiates at least one reference reflecting element with reference measurement light, receives the reference reflected light reflected by the reference reflecting element, and acquires position information of the reference reflecting element in three-dimensional space, and a position measurement unit that irradiates a reflecting element whose position can change relative to the reference reflecting element with measurement light, receives the reflected light reflected by the reflecting element, and acquires position information of the reflecting element in three-dimensional space. ,before The position information of the reference reflecting element acquired by the reference position measurement unit Time change of The reflecting element measured by the position measuring unit is place It is a position measurement device that corrects position information.

[0008] One aspect of the present invention is to irradiate at least one reference reflecting element with reference measurement light, receive the reference reflected light reflected by the reference reflecting element, and acquire position information of the reference reflecting element in three-dimensional space; and irradiate a reflecting element whose position can change relative to the reference reflecting element with measurement light, receive the reflected light reflected by the reflecting element, and acquire position information of the reflecting element in three-dimensional space. ,before Position information of the reference reflective element Time change of Using ,before and correcting the position information of the reflecting element. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of how the position measuring device according to the first embodiment measures the position of a measurement target. [Figure 2] 1 is a diagram illustrating an example of the configuration of a position measurement device according to a first embodiment. [Figure 3] 2 is a diagram showing an example of how the position measurement device according to the first embodiment measures a reference position. FIG. [Figure 4] 1 is a diagram illustrating an example of a functional configuration of a position measurement device according to a first embodiment. [Figure 5] FIG. 4 is a diagram illustrating an example of a position measurement process according to the first embodiment. [Figure 6] FIG. 4 is a diagram illustrating an example of a position information acquisition process according to the first embodiment. [Figure 7] FIG. 6 is a diagram illustrating an example of a reference position information generation process according to the first embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of how a position measurement device according to a modified example of the first embodiment measures a reference position. [Figure 9] 10A and 10B are diagrams illustrating an example of how a position measurement device according to a modified example of the first embodiment corrects errors in position information caused by refractive index fluctuations using a reference light. [Figure 10] FIG. 10 is a diagram illustrating an example of a functional configuration of a position measurement device according to a second embodiment. [Figure 11]FIG. 10 is a diagram showing an example of a cross section of a prism provided in a reflecting element according to a second embodiment. [Figure 12] FIG. 10 is a diagram showing an example of an optical path length difference with respect to an incident angle according to the second embodiment. [Figure 13] FIG. 10 is a diagram showing an example of a graph showing the optical path length difference versus the incident angle according to the second embodiment, enlarged along the axis of the optical path length difference. [Figure 14] FIG. 10 is a diagram illustrating an example of a position measurement process according to the second embodiment. [Figure 15] FIG. 10 is a diagram illustrating an example of the front surface of a reflecting element according to a second embodiment. [Figure 16] 10A and 10B are diagrams illustrating an example of a state in which measurement light is incident on a reflecting element according to a second embodiment. [Figure 17] FIG. 10 is a diagram showing an example of a photographed image captured by a coaxial camera according to the second embodiment. [Figure 18] FIG. 10 is a diagram showing an example of a photographed image captured by a coaxial camera according to the second embodiment. [Figure 19] FIG. 10 is a diagram showing an example of a photographed image captured by a coaxial camera according to the second embodiment. [Figure 20] FIG. 10 is a diagram showing an example of a photographed image captured by a coaxial camera according to the second embodiment. [Figure 21] FIG. 10 is a diagram showing an example of a measurement value correction map according to the second embodiment. [Figure 22] FIG. 10 is a diagram illustrating an example of the configuration of a reflecting element according to a modified example of the second embodiment. [Figure 23] 10 is a diagram showing an example of how the position measuring device according to the third embodiment measures the position of a measurement target. FIG. [Figure 24] 10A and 10B are diagrams showing an example of how the position measurement device according to the third embodiment captures images of a plurality of markers provided on a plurality of reflecting elements, respectively. [Figure 25] FIG. 10 is a diagram showing an example of the appearance of a mobile position measurement device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (First embodiment) The first embodiment will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an example of how a position measuring device 1 according to this embodiment measures the position of a measurement object. In FIG. 1, the measurement object is, for example, a robot T1. The robot T1 has a movable part. The movable part is provided with a tip for processing a material. In the example shown in FIG. 1, the tip is provided with an optical processing head.

[0013] The position measuring device 1 irradiates a measuring light onto a reflecting element 4 arranged on a movable part of a measurement object and receives the reflected light. The position measuring device 1 measures position information based on the light reception result. The position information is information indicating the position of the reflecting element 4 relative to a reference position. The reference position is a predetermined position in space where the reflecting element 4 is arranged.

[0014] The position information is represented by coordinates of a coordinate system (called a reference coordinate system) in the space in which the reflective element 4 is placed. The position information is represented, for example, by rectangular coordinates (X, Y, Z). A set of coordinates X, Y, and Z indicates a position in the rectangular coordinates (X, Y, Z). Note that coordinates X, Y, and Z may also be referred to as distance in the X direction, distance in the Y direction, and distance in the Z direction, respectively.

[0015] The position measuring device 1 transmits the measured position information to the control system of the machine tool or robot. The reference position and coordinate system are shared in advance between the position measuring device 1 and the control system. The control system can obtain the position of the machine tool or robot based on the position information received from the position measuring device 1, so that the machine tool or robot can be calibrated with high precision.

[0016] The position measuring device 1 irradiates a measuring light onto a reflecting element 4 arranged on a movable part of a measurement target and receives the reflected light. First, the position measuring device 1 calculates distance information based on the light reception result. The distance information is information indicating the distance from the position measuring device 1 to the reflecting element 4.

[0017] The position measurement device 1 acquires direction information based on the irradiation direction of the measurement light. The direction information is information indicating the direction of the reflecting element 4 relative to a reference direction. The reference direction is, for example, a direction set in the position measurement device 1 in which the azimuth angle and elevation angle are zero. Alternatively, the reference direction may be the direction of a predetermined reference point viewed from the position measurement device 1. The direction information is represented by a pair of an azimuth angle and an elevation angle (i.e., angle components of spherical coordinates).

[0018] The position measurement device 1 calculates the relative position of the reflecting element 4 with respect to its own device based on the acquired distance information and direction information. The position measurement device 1 calculates the position of the reflecting element 4 with respect to the reference position (i.e., the position of the reflecting element 4 in the reference coordinate system) as position information based on the relative position of the reference position with respect to its own device and the relative position of the reflecting element 4 with respect to its own device.

[0019] The position information may be represented by spherical coordinates or by another orthogonal coordinate system, which is a general term for coordinate systems in which unit vectors are orthogonal to each other. Position is a physical quantity that indicates where an object is located in space. Distance is a physical quantity that indicates the length measured between two points in space. Distance can be, for example, the Euclidean distance.

[0020] Next, we will explain the configuration of the position measuring device 1. Fig. 2 is a diagram showing an example of the configuration of the position measuring device 1 according to this embodiment. The position measuring device 1 includes a housing 10, an optical comb interferometer 11, a four-segment position sensitive detector (PSD) 12, a coaxial camera 13, a beam steering mirror 14, a pointing mirror assembly (PMA) 15, a first half mirror 16, a second half mirror 17, and a reference measurement light irradiator 19 (not shown in Fig. 2).

[0021] The housing 10 is a member for installing the main body of the position measuring device 1 on an installation target. In this embodiment, the installation target is a factory floor or the like. The housing 10 fixes the position measurement device 1 to the installation target by, for example, its own weight. The housing 10 may also include a mechanism for fixing the position measurement device 2 to the installation target.

[0022] The housing 10 also contains the various components of the position measuring device 1. A beam steering mirror 14 and a PMA 15 are provided outside the housing 10. An optical comb interferometer 11, a four-segment PSD 12, a coaxial camera 13, a first half mirror 16, and a second half mirror 17 are provided inside the housing 10. The housing 10 also has a space inside for the propagation of measurement light and reflected light.

[0023] The optical comb interferometer 11 measures the distance from itself to a measurement object. The optical comb interferometer 11 irradiates an optical comb as measurement light onto a reflecting element 4 placed on the measurement object. The optical comb is pulsed light whose spectral intensity is precisely and evenly spaced like a comb on the frequency axis. The optical comb interferometer 11 receives the reflected light generated when the optical comb is reflected by the reflecting element 4.

[0024] In distance measurement using the optical comb interferometer 11, the distance from the optical comb interferometer 11 to the reflecting element 4 is measured based on the position where interference fringes between different pulses of the optical comb occur. The optical comb interferometer 11 can measure the distance with an accuracy on the order of submicrometers, for example.

[0025] The optical comb interferometer 11 includes an irradiation unit, a light receiving unit, and a signal processing unit. The irradiation unit includes a pulsed light source, a frequency control unit, etc. The irradiation unit irradiates the measurement object with pulsed light generated by the pulsed light source as measurement light. The irradiation unit also branches a portion of the pulsed light generated by the pulsed light source and irradiates it as reference light on a reference surface within the optical comb interferometer 11. The light receiving unit includes a photodetector. The photodetector detects the reflected light and the reference light irradiated on the reference surface. When the detection result from the photodetector is input, the signal processing unit calculates the distance from the optical comb interferometer 11 to the reflecting element 4 based on the position where interference fringes between the reflected light and the reference light occur.

[0026] Here, the measurement light emitted by the optical comb interferometer 11 passes through a first half mirror 16 and a second half mirror 17, and is then reflected by a beam steering mirror 14 and irradiated onto the reflecting element 4. Here, the optical path of the measurement light irradiated onto the reflecting element 4 and the reflected light reflected by the reflecting element 4 share a portion in common.

[0027] The coaxial camera 13 captures an image of the reflecting element 4, which is the object to be measured. The coaxial camera 13 captures an image of the reflecting element 4 by using light reflected by the reflecting element 4 from natural light.

[0028] The coaxial camera 13 is used to capture the position of the reflecting element 4. The coaxial camera 13 captures an image of the reflecting element 4, and the position measuring device 1 roughly captures the position of the reflecting element 4 and adjusts the direction in which the measurement light is irradiated. Image A1 is an example of an image of the reflecting element 4 captured by the coaxial camera 13. The imaging center of the coaxial camera 13 is adjusted to coincide with the optical axis of the measurement light of the optical comb interferometer 11. Therefore, the small circle at the center of image A1 is the position of the measurement light, and the incident position on the reflecting element 4 can be detected.

[0029] The four-segment PSD 12 detects the incident position of the reflected light on the light receiving section by detecting the reflected light from the reflecting element 4. The reflected light is measurement light irradiated by the optical comb interferometer 11 and reflected by the reflecting element 4. A portion of the reflected light is reflected by the first half mirror 16 and enters the four-segment PSD 12.

[0030] The four-segment PSD 12 includes, for example, photodiodes and resistors. The photodiodes are arranged in an array. In other words, the four-segment PSD 12 includes a photodiode array. The detection surface of the four-segment PSD 12 is divided into four. The four-segment PSD 12 measures the position of the spot light based on the light intensity of the spot light of reflected light detected on each of the four divided detection surfaces. Therefore, the four-segment PSD 12 is a photoelectric detection device that detects the amount of reflected light. The four-segment PSD 12 is an example of a reflected light detection unit.

[0031] The four-segment PSD 12 is used to roughly capture the position of the reflecting element 4 using the coaxial camera 13, and then fine-tune the direction of the measurement light so that the reflected light returns (incidents) appropriately to the optical comb interferometer 11. The position measuring device 1 may include another position detector instead of the four-segment PSD 12. Examples of other position detectors include a line sensor and a distance measuring device using a phase detection method.

[0032] In this embodiment, the coaxial camera 13 is provided as an imaging unit separate from the reflected light detection unit, but this is not limiting. The four-segment PSD 12 may be omitted from the configuration of the position measurement device 1, and the coaxial camera 13 may be used as the reflected light detection unit.

[0033] The beam steering mirror 14 reflects the measurement light emitted from the optical comb interferometer 11 toward the reflecting element 4. The beam steering mirror 14 also reflects the measurement light reflected from the reflecting element 4 toward the optical comb interferometer 11.

[0034] The PMA 15 moves (changes) the direction of the beam steering mirror 14. For example, the PMA 15 includes a gimbal unit and a rotary encoder (not shown). The orientation of the beam steering mirror 14 is changed by driving the gimbal unit. The gimbal unit can rotate the beam steering mirror 14 in both the longitude direction (azimuth angle direction) and the latitude direction (elevation angle direction). The rotary encoder measures the rotation angle of the gimbal unit.

[0035] Here, the optical path of the reflected light used for imaging by the above-described coaxial camera 13 is partially common to the optical path of the measurement light or reflected light used for distance measurement by the above-described optical comb interferometer 11. In other words, at least a part of the optical path of the optical system for imaging by the first imaging unit 23 is common to at least a part of the optical path of the optical system for receiving light by the light receiving unit provided in the optical comb interferometer 11.

[0036] The irradiation direction of the measurement light is coaxial with the imaging direction of the coaxial camera 13. The imaging direction of the coaxial camera 13 is changed by changing the orientation of the beam steering mirror 14, which changes the direction of the measurement light emitted by the optical comb interferometer 11. In other words, the beam steering mirror 14 is used both to change the irradiation direction of the measurement light emitted by the optical comb interferometer 11 and to change the imaging direction of the coaxial camera 13.

[0037] The position measuring device 1 may include a camera outside the housing 10 instead of or in addition to the coaxial camera 13. In this camera, the optical path of the reflected light used for imaging is not the same as the optical path of the measurement light or reflected light used by the optical comb interferometer 11 to measure distance. In this case, a drive mechanism is provided to change the imaging direction of the camera. The camera may be, for example, a wide-angle camera that can capture images of the surroundings of the position measuring device 1.

[0038] The first half mirror 16 transmits the measurement light emitted from the optical comb interferometer 11. The first half mirror 16 also transmits a portion of the measurement light reflected by the reflecting element 4 toward the optical comb interferometer 11, and reflects the remaining portion toward the four-segment PSD 12.

[0039] The second half mirror 17 transmits the measurement light emitted from the optical comb interferometer 11. The second half mirror 17 also transmits a portion of the measurement light reflected by the reflecting element 4 toward the optical comb interferometer 11. The second half mirror 17 also reflects the natural light reflected by the reflecting element 4 toward the coaxial camera 13.

[0040] The reflective element 4 is placed on the object to be measured. The reflective element 4 is placed on a moving part of the object to be measured, such as a machine tool or a robot. One example of the reflective element 4 is a retroreflector. A retroreflector is an optical element that reflects a beam back in the incident direction, regardless of the position or direction from which the beam is incident on the retroreflector. In other words, a retroreflector has a retroreflection function.

[0041] The reference measurement light irradiator 19 is provided as part of the optical comb interferometer 11. The reference measurement light irradiator 19 includes a first reference irradiator, a second reference irradiator, and a third reference irradiator. In this embodiment, the position measuring device 1 includes an optical system inside the housing 10 for branching the measurement light emitted from the optical comb interferometer 11. In the position measuring device 1, the optical system can branch the measurement light into up to eight beams. In this embodiment, the first, second, and third reference measurement beams irradiated by the reference measurement beam irradiator 19 are beams branched from the measurement light emitted from the optical comb interferometer 11. That is, the measurement light of the distance measurement unit 200 and the reference measurement light of the reference distance measurement unit 210 are supplied by splitting from the same light source.

[0042] FIG. 3 is a diagram showing an example of how the position measuring device 1 according to this embodiment performs measurement. In this embodiment, the object to be measured is, for example, a movable part of a machine tool. In this embodiment, the reflecting element 4 is disposed on the movable part T2 of the machine tool. That is, the reflecting element 4 is provided on a movable object to be measured. In this embodiment, the machine tool has a machining head, which has an end effector such as an end mill. For example, the movable part T2 of the machine tool is a mechanism for changing the angle and position of the end mill to a desired angle and position. The reference reflecting element 5, for example, consists of three elements: a first reference reflecting element 5-1, a second reference reflecting element 5-2, and a third reference reflecting element 5-3. In this embodiment, the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3 are placed on a surface plate on which a workpiece to be machined by a machine tool is placed. In other words, the reference reflecting element 5 is provided on a measurement reference object that is different from the measurement object on which the reflecting element 4 is provided.

[0043] A three-dimensional coordinate system (reference coordinate system) and a reference (for example, the origin of the reference coordinate system) are set based on the positions of the multiple reference reflecting elements 5. The position of the origin of the three-dimensional coordinate system is, for example, the position of one of the multiple reference reflecting elements 5. Details of setting the reference coordinate system and the reference (origin) will be described later. In the following description, the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3 may be collectively referred to as a plurality of reference reflecting elements 5.

[0044] Each of the plurality of reference reflective elements 5 is a retroreflector, that is, each of the plurality of reference reflective elements 5 has a retroreflection function similar to the reflective element 4.

[0045] 4 is a diagram showing an example of the functional configuration of the position measurement device 1 according to this embodiment. The position measurement device 1 includes a position measurement unit 20, a reference position measurement unit 21, a control unit 22, a first imaging unit 23, a reflected light detection unit 24, a communication unit 25, and a calculation unit 26.

[0046] The position measurement unit 20 includes a distance measurement unit 200 , an irradiation direction movement unit 201 , an irradiation direction measurement unit 202 , and a position information acquisition unit 203 . The distance measurement unit 200 irradiates the reflecting element 4 with measurement light and receives the reflected light to measure the distance to the reflecting element. The distance measurement unit 200 includes an irradiation unit, a light receiving unit, and a signal processing unit. The irradiation unit irradiates the reflecting element arranged on the movable part of the measurement object with measurement light. The light receiving unit receives the reflected light. The signal processing unit processes the signal from the light receiving unit to obtain distance information to the reflecting element 4. The distance measurement unit 200 includes an optical comb interferometer 11. The irradiation unit includes a pulsed light source provided in the optical comb interferometer 11. The light receiving unit includes a light receiving unit provided in the optical comb interferometer 11. The signal processing unit includes a signal processing unit provided in the optical comb interferometer 11.

[0047] The irradiation direction moving unit 201 changes the irradiation direction of the measurement light. Changing the irradiation direction is also referred to as moving the irradiation direction. The irradiation direction moving unit 201 moves the irradiation direction in accordance with the movement of the reflected light detected by the reflected light detection unit 24. The irradiation direction moving unit 201 includes a gimbal unit included in the PMA 15. In this embodiment, as described above, the beam steering mirror 14 is used both to change the irradiation direction of the measurement light emitted by the optical comb interferometer 11 and to change the imaging direction of the coaxial camera 13. Accordingly, the irradiation direction moving unit 201 includes an imaging adjustment unit. The imaging adjustment unit adjusts the imaging direction of the first imaging unit 23. Therefore, the irradiation direction moving unit 201 moves the irradiation direction of the measurement light and the imaging direction of the first imaging unit 23 simultaneously.

[0048] The irradiation direction measurement unit 202 measures the irradiation direction of the measurement light. The irradiation direction measurement unit 202 includes a rotary encoder included in the PMA 15. The irradiation direction measurement unit 202 outputs the measurement result of the irradiation direction to the position information acquisition unit 203 of the distance measurement unit 200 as direction information.

[0049] The position information acquisition unit 203 acquires the position (position information) of the reflecting element 4 in three-dimensional space from the distance (distance information) to the reflecting element 4 measured by the distance measurement unit 200 and the irradiation direction (direction information) of the measurement light measured by the irradiation direction measurement unit 202. The acquisition of the position information will be described in detail later.

[0050] As an example, reference position measurement unit 21 is made up of three components: reference position measurement unit 21-1, reference position measurement unit 21-2, and reference position measurement unit 21-3. In the following description, reference position measurement unit 21-1, reference position measurement unit 21-2, and reference position measurement unit 21-3 may be collectively referred to as reference position measurement unit 21. Because reference position measurement unit 21-1, reference position measurement unit 21-2, and reference position measurement unit 21-3 have similar functions, the functional configuration of reference position measurement unit 21 will be described here, with reference position measurement unit 21-1 representing reference position measurement unit 21, and descriptions of reference position measurement unit 21-2 and reference position measurement unit 21-3 will be omitted.

[0051] The reference position measurement unit 21-1 includes a reference distance measurement unit 210-1, a reference irradiation direction movement unit 211-1, a reference irradiation direction measurement unit 212-1, and a reference position information acquisition unit 213-1.

[0052] The reference distance measurement unit 210-1 irradiates the first reference reflecting element 5-1 with reference measurement light and receives the reference reflected light to measure the distance to the first reference reflecting element 5-1. The reference distance measurement unit 210-1 includes a first reference irradiating unit, a first reference light receiving unit, and a first reference signal processing unit.

[0053] The first reference irradiator irradiates the first reference reflecting element 5-1 with the first reference measurement light. The first reference irradiator includes an optical system for splitting the measurement light emitted from the optical comb interferometer 11. The first reference light receiving section receives the first reference reflected light from the first reference reflecting element 5-1.

[0054] The first reference signal processing unit processes the signal from the first reference light receiving unit to obtain first reference distance information, which is information indicating the distance from the position measurement device 1 to the first reference reflecting element 5-1.

[0055] The reference irradiation direction moving unit 211-1 changes the irradiation direction of the reference measurement light. Changing the irradiation direction is also referred to as moving the irradiation direction. The reference irradiation direction moving unit 211-1 includes a gimbal unit included in the PMA 15. The reference irradiation direction measurement unit 212-1 measures the irradiation direction of the reference measurement light. The reference position information acquisition unit 213-1 acquires the position of the first reference reflecting element 5-1 in three-dimensional space (first reference position information) from the distance (distance information) to the first reference reflecting element 5-1 measured by the reference distance measurement unit 210 and the irradiation direction (direction information) of the reference measurement light measured by the reference irradiation direction measurement unit 212-1. The acquisition of the reference position information will be described in detail later.

[0056] The reference position measurement unit 21-2 irradiates the second reference reflecting element 5-2 with a reference measurement light and receives the reference reflected light to measure the position of the second reference reflecting element 5-2. The reference position measurement unit 21-3 irradiates the third reference reflecting element 5-3 with a reference measurement light and receives the reference reflected light to measure the position of the third reference reflecting element 5-3. The functional configurations of the reference position measurement unit 21-2 and the reference position measurement unit 21-3 are the same as those of the reference position measurement unit 21-1, so detailed explanations will be omitted.

[0057] Note that any one of reference distance measurement unit 210-1, reference distance measurement unit 210-2, and reference distance measurement unit 210-3 may be simply referred to as reference distance measurement unit 210. Also, reference distance measurement unit 210-1, reference distance measurement unit 210-2, and reference distance measurement unit 210-3 may be collectively referred to as multiple reference distance measurement units 210. Furthermore, any one of the reference irradiation direction moving unit 211-1, the reference irradiation direction moving unit 211-2, and the reference irradiation direction moving unit 211-3 may be simply referred to as the reference irradiation direction moving unit 211. Furthermore, the reference irradiation direction moving unit 211-1, the reference irradiation direction moving unit 211-2, and the reference irradiation direction moving unit 211-3 may be collectively referred to as the plurality of reference irradiation direction moving units 211. Furthermore, any one of the reference irradiation direction measuring unit 212-1, the reference irradiation direction measuring unit 212-2, and the reference irradiation direction measuring unit 212-3 may be simply referred to as the reference irradiation direction measuring unit 212. Furthermore, the reference irradiation direction measuring unit 212-1, the reference irradiation direction measuring unit 212-2, and the reference irradiation direction measuring unit 212-3 may be collectively referred to as the plurality of reference irradiation direction measuring units 212. Furthermore, any one of reference position information acquisition unit 213-1, reference position information acquisition unit 213-2, and reference position information acquisition unit 213-3 may be simply referred to as reference position information acquisition unit 213. Furthermore, reference position information acquisition unit 213-1, reference position information acquisition unit 213-2, and reference position information acquisition unit 213-3 may be collectively referred to as a plurality of reference position information acquisition units 213.

[0058] The control unit 22 controls each device and component included in the position measurement device 2. The control unit 22 includes, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and an FPGA (Field-Programmable Gate Array), and performs various calculations and information exchange. The control unit 22 reads a program from the ROM and executes various controls in accordance with the read program.

[0059] The control unit 22 and the other devices and components included in the position measurement device 1 are connected by, for example, a signal line. The control unit 22 and the other devices and components included in the position measurement device 2 may communicate with each other by short-range wireless communication.

[0060] The control unit 22 causes a calculation unit 26 to execute some of the various calculations. The control unit 22 also includes an imaging adjustment unit.

[0061] The calculation unit 26 includes a reference coordinate setting unit 260 and a first correction unit 261. The reference coordinate setting unit 260 sets a reference (origin) and a reference coordinate system based on the first reference position information, the second reference position information, and the third reference position information.

[0062] The first correction unit 261 acquires position information of the reflecting element 4 relative to the reference generated by the reference coordinate setting unit 260. The position information of the reflecting element 4 relative to the reference includes position information of the reflecting element 4 in the set reference coordinate system. The first correction unit 261 further corrects fluctuations in the position information of the reflecting element 4 relative to the reference.

[0063] The first imaging unit 23 captures an image of the reflecting element 4. The first imaging unit 23 includes a coaxial camera 13. The reflected light detector 24 detects the reflected light from the reflecting element 4. The reflected light detector 24 detects the movement of the reflected light that moves in accordance with the movement of the reflecting element 4. The reflected light detector 24 includes a four-split PSD 12.

[0064] The communication unit 25 communicates with an external device. The external device is, for example, a control system that controls a robot in which the reflective element 4 is installed. The communication unit 25 includes a transmission unit and a reception unit. The transmission unit transmits the position information of the reflective element 4 acquired by a position information acquisition unit included in the distance measurement unit 200 to the control system. The communication unit 25 includes a communication interface (I / F) for communicating via a wireless network.

[0065] For example, a fifth generation mobile communication system or a mobile communication system using light with a wavelength shorter than millimeter waves may be used for communication by the communication unit 25. In the fifth generation mobile communication system, frequency bands of 450 MHz to 6000 MHz and 24250 MHz to 52600 MHz are used.

[0066] Next, the position measurement process by the position measurement device 1 will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of the position measurement process according to this embodiment. The position measurement process is executed by the control unit 22.

[0067] The position measurement unit 20 acquires position information of the reflecting element 4 (step S10). The process of acquiring the position information of the reflecting element 4 is called a position measurement process. The position measurement unit 20 irradiates the reflecting element 4 with measurement light, receives the light reflected by the reflecting element 4, and acquires position information of the reflecting element 4 in three-dimensional space.

[0068] The location information acquisition process in step S10 will now be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the location information acquisition process according to this embodiment.

[0069] The control unit 22 uses the first imaging unit 23 to capture an image of the reflecting element 4 (step S110). Note that the control unit 22 may use the first imaging unit 23 to capture an image of at least a part of the robot to be measured and / or the reflecting element 4.

[0070] The imaging adjustment unit included in the control unit 22 adjusts the imaging direction of the first imaging unit 23 so that the reflective element 4 is included in the imaging range of the first imaging unit 23. The imaging direction is, for example, the direction of the optical axis of the imaging lens. When adjusting the imaging direction of the first imaging unit 23, the imaging adjustment unit may adjust the imaging direction of the first imaging unit 23 so that the direction of the optical axis of the imaging lens overlaps with the reflective element 4, or may adjust the imaging range so that the reflective element 4 is included in the imaging range even if it does not overlap. The imaging adjustment unit determines whether the reflective element 4 is included in the imaging range of the first imaging unit 23 based on the image captured by the first imaging unit 23. The imaging adjustment unit has an image analysis function and determines the image of the reflective element 4 by analyzing the image captured by the first imaging unit 23. The imaging adjustment unit determines the image of the reflective element 4 based on, for example, pattern matching. The irradiation direction movement unit 201 may learn images of the reflective element 4 in advance using AI (machine learning) and determine the image of the reflective element 4 based on the learning results.

[0071] Regarding the imaging direction of the first imaging unit 23, the position at which the position measurement device 1 is installed and / or the orientation of the housing 10 may be adjusted in advance so that the imaging range of the first imaging unit 23 includes the reflective element 4. In this case, the imaging adjustment unit may be omitted from the configuration of the control unit 22.

[0072] Based on the imaging result by the first imaging unit 23, the control unit 22 controls the irradiation direction shifting unit 201 so that the measurement light is irradiated onto the reflecting element 4 (step S120). The irradiation direction shifting unit 201 changes the orientation of the beam steering mirror 14 using the irradiation direction measurement result obtained by the rotary encoder. The irradiation direction shifting unit 201 changes the orientation of the beam steering mirror 14 in the longitude direction and / or the latitude direction via the gimbal unit. In other words, the irradiation direction shifting unit 201 shifts the irradiation direction in accordance with a command from the control unit 22 so that the measurement light is irradiated onto the reflecting element 4 that is the measurement target determined based on the imaging result by the first imaging unit 23.

[0073] Furthermore, the control unit 22 controls the irradiation direction moving unit 201 so that the measurement light follows the movement of the reflective element 4 to be measured, based on the imaging result by the first imaging unit 23. Since the irradiation direction moving unit 201 is driven so that the measurement light follows the reflective element 4, even if the reflective element 4 moves, the measurement light continues to irradiate the reflective element 4, and the first imaging unit 23 can continue to image the reflective element 4.

[0074] In the process of tracking the reflecting element 4 by the irradiation direction moving unit 201, the image capturing adjustment unit repeatedly executes image analysis to identify and capture the image of the reflecting element 4 at each time.

[0075] In this way, the measurement light from the optical comb interferometer 11 included in the distance measurement unit 200 is irradiated toward the reflecting element 4 (step S130). When the measurement light is irradiated onto the reflecting element 4, the reflected light is reflected by total reflection.

[0076] The reflective element 4 does not have to be a total reflection element. For example, a corner cube reflector may be used as the reflective element 4. The corner cube reflector may be a corner cube reflective element having a reflection-enhancing coating. The reflective element 4 may also be a ball reflector or a cat's eye.

[0077] The reflected light from the reflecting element 4 travels along the same path as the measurement light in the opposite direction and is received by the light receiving unit of the distance measurement unit 200, which includes the optical comb interferometer 11 (step S140). A portion of the reflected light is detected by the four-segment PSD 12. Based on the detection result from the four-segment PSD 12, the control unit 22 again controls the irradiation direction shifting unit 201 so that the measurement light continues to be irradiated onto the reflecting element 4. Here, based on the detection result from the four-segment PSD 12, the control unit 22 fine-tunes the irradiation direction of the measurement light using the irradiation direction shifting unit 201.

[0078] Furthermore, by using the optical comb interferometer 11, the position measuring device 1 can continue measuring with an accuracy on the order of submicrometers even if the reflected light is lost during the measurement process, by receiving the reflected light again and returning to measurement.

[0079] The position information acquisition unit 203 acquires position information of the reflecting element 4 from the detection result (distance information) by the distance measurement unit 200 including the optical comb interferometer 11 and the direction information measured by the irradiation direction measurement unit 202 (step S150). The acquired position information is output to the calculation unit 26 via the control unit 22. The position information is expressed in three-dimensional spherical coordinates with the position measurement device 1 as the reference.

[0080] As described above, the position measurement unit 20 acquires position information of the reflecting element 4 in three-dimensional space from the distance (distance information) to the reflecting element 4 measured by the distance measurement unit 200 and the irradiation direction (direction information) measured by the irradiation direction measurement unit 202.

[0081] Returning to FIG. 5, the description of the position measurement process will be continued. The reference position measuring unit 21 acquires reference position information of the reference reflecting element 5 (step S20). The reference position measuring unit 21 irradiates at least one reference reflecting element 5 with reference measurement light, receives the reference reflected light reflected by the reference reflecting element 5, and acquires position information (reference position information) of the reference reflecting element 5 in three-dimensional space. As described above, the position measuring device 1 includes a plurality of reference position measuring units 21. The plurality of reference reflecting elements 5 acquire position information of different reference reflecting elements 5, respectively.

[0082] Here, with reference to Fig. 7, the process by which the reference position measurement unit 21-1 generates reference position information of the reference reflecting element 5 (referred to as reference position information generation process) will be described in detail. Fig. 7 is a diagram showing an example of the reference position information generation process according to this embodiment. The processes from step S310 to step S350 shown in Fig. 7 are executed as the process of step S20 shown in Fig. 5. The processes from step S310 to step S350 shown in FIG. 7 may be executed at the start of measurement.

[0083] The control unit 22 uses the first imaging unit 23 to capture images of the plurality of reference reflecting elements 5 (step S310).

[0084] The control unit 22 controls each of the plurality of reference irradiation direction moving units 211 so that each of the three reference measurement beams is irradiated onto each of the plurality of reference reflecting elements 5 (step S320). In the control of step S320, the control unit 22 uses the imaging results of the images of the plurality of reference reflecting elements 5 by the first imaging unit 23.

[0085] The control unit 22 controls the reference irradiation direction moving unit 211 so that the reference measurement light beams are irradiated onto the reference reflecting elements 5, respectively (step S330). The control unit 22 may cause the reference irradiation units to irradiate the reference measurement light beams simultaneously or sequentially.

[0086] The reflected light from the reference reflecting element 5 travels in the opposite direction along the same path as the reference measurement light, and is received by the reference light receiving section provided in the reference distance measurement section 210 (step S340).

[0087] The reference position information acquisition unit 213 acquires reference position information of the reference reflecting element 5 from the measurement result (reference distance information) by the reference distance measurement unit 210 and the reference irradiation direction information acquired by the reference irradiation direction measurement unit 212 (step S350). In this embodiment, the reference position generation process described here is performed in each of the reference position measurement units 21-1, 21-2, and 21-3, and first reference position information, second reference position information, and third reference position information are acquired. The acquired first, second, and third reference position information are output to the calculation unit 26 via the control unit 22. The reference position information is expressed in three-dimensional spherical coordinates with the position measurement device 1 as the reference.

[0088] As described above, the reference position measurement unit 21 acquires position information of the reference reflecting element 5 in three-dimensional space from the distance to the reference reflecting element 5 measured by the reference distance measurement unit 210 and the irradiation direction of the reference measurement light measured by the reference irradiation direction measurement unit 212.

[0089] Returning to FIG. 5, the description of the position measurement process will be continued. The reference coordinate setting unit 260 included in the calculation unit 26 sets a reference (origin) and a reference coordinate system based on the first, second, and third reference position information acquired by the reference position measurement unit 21 and obtained via the control unit 22 (step S30). In this embodiment, at least three pieces of reference position information, first to third, are acquired, and the reference coordinate setting unit 260 sets a desired Cartesian coordinate system (reference coordinate system) based on these three pieces of reference position information.

[0090] The reference coordinate system can be arbitrarily set in the space in which the measurement object (reflecting element 4) moves, depending on the installation positions of the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3. For example, as shown in FIG. 3, a Cartesian coordinate system can be set as the reference coordinate system, with respect to the space in which the movable part T2 of the measurement object moves, so as to include two axes parallel to the surface of the table on which the measurement object is placed. Furthermore, the reference coordinate setting unit 260 sets an origin as a reference within the reference coordinate system. The origin may be any of the three elements: the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3 (reference position).

[0091] Alternatively, the movable part T2 (and thus the reflecting element 4), which is the object to be measured, may be positioned at a predetermined position in the reference coordinate system, for example, at the origin of the movable part T2 determined by the machine tool, and the position information of the reflecting element 4 at that time may be made to coincide with the origin of the reference coordinate system. This makes it possible to make the position information acquired by the position measurement unit 20 and the position information acquired by the reference position measurement unit 21 identical for the same position in space, thereby eliminating (correcting) any discrepancy between the position information acquired by the position measurement unit 20 and the position information acquired by the reference position measurement unit 21. In either case, the reference coordinate system and the reference (origin) are set based on the reference position information obtained from the reference reflecting element.

[0092] The first correction unit 261 included in the calculation unit 26 converts the position information of the reflecting element 4 into position information in the reference coordinate system (step S40). The first correction unit 261 converts the position information of the reflecting element 4 measured by the position measurement unit 20 from three-dimensional spherical coordinates based on the position measurement device 1 into Cartesian coordinates in the reference coordinate system set by the reference coordinate setting unit 260. This makes it possible to acquire the position information of the measurement object (i.e., the position information of the reflecting element 4) in Cartesian coordinates in the reference coordinate system in the space in which the measurement object moves.

[0093] Incidentally, the relative positional relationship between the position measurement device 1 and the object to be measured (reflective element 4) may fluctuate due to floor vibrations, vibrations caused by robot operation, or the like, regardless of the movement of the object to be measured. These fluctuations occur over time and include both short-term fluctuations (vibrations) and long-term fluctuations (origin drift). Such fluctuations in the relative positional relationship result in a decrease in the accuracy of measuring the position information of the object to be measured by the position measurement device 1. Therefore, the first correction unit 261 corrects the position information of the reflective element 4 using the reference position information of the reference reflective element 5 (step S50).

[0094] The correction may include resetting the reference (origin) and the reference coordinate system set in step S30. For example, after starting to acquire position information, an operation similar to step S30 may be performed at regular or irregular intervals to acquire the deviation of the reference coordinate system and correct the deviation. This allows the fluctuation of the origin over time to be calibrated (origin calibration). Alternatively, reference position information of the reference reflecting element 5 may be constantly acquired, and fluctuations in the reference (origin) and reference coordinate system may be constantly corrected. In this case, fluctuations (vibrations) over a short period of time can also be corrected.

[0095] In this way, by placing the reference reflecting element 5 on a measurement reference object that serves as a reference for measuring the position of the measurement object, and setting a reference coordinate system and an origin based on the reference position information of the reference reflecting element 5 acquired by the position measurement device 1, it is possible to cancel (correct) fluctuations in the relative positional relationship between the position measurement device 1 and the measurement object (reflecting element 4). In this sense, the conversion of the position information of the reflecting element 4 into position information in the reference coordinate system, performed by the first correction unit 261, can also be said to be a correction of the position information of the reflecting element 4.

[0096] The control unit 22 transmits the corrected position information to the control system (step S60). With this, the control unit 22 ends the position measurement process.

[0097] (Modification 1 of the first embodiment) In this embodiment, an example in which the reference reflecting element 5 is placed on a surface plate has been described. As a modification of this embodiment, a case in which the reference reflecting element 5 is placed on a workpiece will be described. Fig. 8 is a diagram showing an example of how the position measuring device 1 according to this modification measures the reference position. In Fig. 8, the position measuring device 1 is placed in a processing device equipped with a robot T3. The robot T3 processes a workpiece W1 placed in the processing device.

[0098] The first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3 are placed on the workpiece W1. The workpiece W1 is a large workpiece with sufficiently high rigidity. If the workpiece is a large workpiece with sufficiently high rigidity like the workpiece W1, the reference reflecting element 5 may be placed on the workpiece as in this modified example.

[0099] Here, in the process in which the robot T3 processes the workpiece W1, the robot T3 may vibrate the position measuring device 1 via the housing of the processing device. Furthermore, even if the position measuring device 1 is installed on the floor, in the process in which the robot T3 processes the workpiece W1, the position measuring device 1 may vibrate. Therefore, it is preferable that the position measuring device 1 be installed in a vibration-proof and / or vibration-damped state. When the position measuring device 1 is vibration-proof and / or vibration-damped, the position measuring device 1 and the workpiece W1 can be regarded as rigid bodies.

[0100] (Modification 2 of the first embodiment) When realizing ultra-high-precision three-dimensional coordinate measurement using the position measuring device 1, the influence of variations in the refractive index of the atmosphere caused by fluctuations in the temperature, humidity, and atmospheric pressure of the measurement environment on errors in the measured position information cannot be ignored. In this modified example, a case will be described in which errors in the position information caused by variations in the refractive index are corrected using a reference light.

[0101] The temperature and atmospheric pressure of the environment may fluctuate over time. Fluctuations in temperature and atmospheric pressure cause fluctuations in the refractive index. In the position measurement device 1, position information is acquired using the optical comb interferometer 11, and thus fluctuations in the refractive index can result in errors in fluctuations in the position information of the reflective element.

[0102] 9 is a diagram showing an example of how the position measuring device 1 according to this modified example corrects errors in position information due to refractive index fluctuations using the reference light R1. In FIG. 9, the reference reflecting element 5-4 is placed on a base together with the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3. The reference reflecting element 5-4 has the same configuration as the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3, respectively, except that the reference reflecting element 5-4 is placed at a different position from the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3, respectively.

[0103] The position measurement device 1 irradiates the reference reflecting element 5-4 with reference light R1 from the reference measurement light irradiator 19. In this modification, one of the first reference irradiator, the second reference irradiator, and the third reference irradiator provided in the reference measurement light irradiator 19 irradiates the reference measurement light as the reference light R1. In this modification, as an example, the first reference irradiator irradiates the reference light R1.

[0104] The reference measurement light irradiator 19 may include a reference light irradiator that irradiates reference light R1, separate from the first reference irradiator, second reference irradiator, and third reference irradiator. In this case, the reference light irradiator uses, as reference light R1, light that is branched from the measurement light emitted from the optical comb interferometer 11. The position measurement device 1 may include a pulsed light source for irradiating reference light R1 separate from the pulsed light source provided in the optical comb interferometer 11, and the reference light irradiator may irradiate, as reference light R1, pulsed light emitted from the pulsed light source for irradiating reference light R1.

[0105] The position measurement device 1 acquires distance information from the position measurement device 1 to the reference reflecting element 5-4 based on the reference light R1 irradiated onto the reference reflecting element 5-4 under a predetermined environment (hereinafter sometimes referred to as a reference environment). The predetermined environment (reference environment) is an environment indicated by the temperature and air pressure of the space in which the reference reflecting element 5-4 is placed. The acquired distance information differs depending on the environment. In this second variant, the reference reflecting element 5-4 is placed on a base plate, but it may be placed anywhere that represents the environment (temperature, air pressure, etc.) in which the reflecting element 4, the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3 are installed.

[0106] In an environment where the position information of the reflecting element 4 is measured (hereinafter, sometimes referred to as the measurement environment), the position measurement device 1 acquires distance information from the position measurement device 1 to the reference reflecting element 5-4 based on the reference light R1 while measuring the position information of the reflecting element 4. The distance between the position measurement device 1 and the reference reflecting element 5-4 is known. The position measurement device 1 compares the distance information acquired in the measurement environment with the known distance information to the reference reflecting element 5-4 and calculates the ratio of the two (correction coefficient). The position measurement device 1 multiplies the acquired position information of the reflecting element 4 by the correction coefficient to correct the position information. In this way, the position measurement device 1 corrects errors in the position information due to refractive index fluctuations.

[0107] In this modification, the first reference irradiator irradiates the reference reflecting element 5-4 with the reference light R1 and compares it with a known distance, but this is not limited to this. For example, a reference reflecting element 5-5 may be provided separately from the reference reflecting element 5-4, and the first reference irradiator irradiates the reference reflecting element 5-4 and the reference reflecting element 5-5 sequentially with the reference light R1 to acquire position information. The relative positional relationship between the reference reflecting element 5-4 and the reference reflecting element 5-5 is known. This allows the correction coefficient to be calculated from the known relative positional relationship between the reference reflecting element 5-4 and the reference reflecting element 5-5 and the measured positional relationship. Instead of the reference reflecting elements 5-4 and 5-5, any one or two of the first reference reflecting element 5-1, the second reference reflecting element 5-2, and the third reference reflecting element 5-3 may be used to calculate the correction coefficient.

[0108] As described above, in this modification, the position measurement device 1 corrects the position information of the reflecting element 4 measured by the position measurement unit 20 using the position information of the reference reflecting element 5 acquired by the reference position measurement unit 21. Here, the correction includes correcting fluctuations in the position information of the reflecting element 4 over time. The correction also includes correcting errors in the position information of the reflecting element 4 caused by the temperature and air pressure of the space in which the reflecting element 4 and the reference reflecting element 5 are placed, based on the position information of the reference reflecting element 5 acquired by the reference position measurement unit 21.

[0109] The position measuring device 1 may acquire position information of a robot arm provided in a coordinate measuring machine (CMM). In this case, the reflecting element 4 is provided on a movable part of the robot arm. The reference reflecting element 5 is provided, for example, on the floor of the CMM. The CMM floor is a part of the CMM configuration that is different from the robot arm. The robot arm and the CMM floor constitute the CMM. In other words, the measurement object and the measurement reference object constitute a single device. In this case, the position measuring device 1 can determine an apparatus coordinate system that serves as the reference for the position information of the measurement object in the single device, based on the position information of the reference reflecting element 5 acquired by the reference position measuring unit 21, and the position measuring device 1 can calibrate or correct the apparatus coordinate system of the CMM itself, which is a single device.

[0110] As described above, the position measuring device 1 according to this embodiment and its modified example includes the position measuring unit 20 and the reference position measuring unit 21. The position measurement unit 20 irradiates the reflecting element 4 with measurement light, receives the light reflected by the reflecting element 4, and acquires position information of the reflecting element 4 in three-dimensional space. The reference position measuring unit 21 irradiates at least one reference reflecting element 5 with reference measurement light, receives the reference reflected light reflected by the reference reflecting element 5, and acquires position information of the reference reflecting element 5 in three-dimensional space. The position measuring device 1 corrects the position information of the reflecting element 4 measured by the position measuring unit 20 using the position information of the reference reflecting element 5 acquired by the reference position measuring unit 21.

[0111] With this configuration, the position measuring device 1 of this embodiment and its variants can correct the position information of the reflecting element 4 using the position information of the reference reflecting element 5, thereby improving the accuracy of the position information compared to when no correction is made. For example, in controlling a robot, the position measuring device 1 measures the position information of a reflecting element 4 installed on the robot and corrects the position information, thereby being able to measure the position of the robot with high accuracy.

[0112] The position measurement device 1 according to this embodiment and its modified example includes a first position measurement unit (position measurement unit 20 in this embodiment) and a second position measurement unit (reference position measurement unit 21 in this embodiment). a first position measurement unit (position measurement unit 20 in this embodiment) that irradiates a first measurement light (measurement light in this embodiment) onto the reflecting element 4, receives a first reflected light (reflected light in this embodiment) reflected by the reflecting element 4, and acquires position information of the reflecting element 4 in three-dimensional space; The second position measurement unit (in this embodiment, the reference position measurement unit 21) irradiates the reflecting element with second measurement light (in this embodiment, the reference measurement light) and receives the second reflected light (in this embodiment, the reference reflected light) reflected by the reflecting element 4, thereby acquiring position information of the reflecting element 4 in three-dimensional space.

[0113] With this configuration, the position measuring device 1 of this embodiment can irradiate the reflecting element 4 with the first measuring light and the second measuring light to obtain position information of the reflecting element 4 in three-dimensional space, thereby improving the accuracy of the position information compared to when only the first measuring light is used.

[0114] (Second embodiment) The second embodiment of the present invention will be described in detail below with reference to the drawings. In the first embodiment, the position measurement device 1 corrects errors in the position information of the reflecting element due to fluctuations in the distance between the device itself and the reference position, and the temperature and air pressure in the space. In this embodiment, the position information is corrected based on the incident angle at which the measurement light is incident on the reflecting element, the incident position within the incident surface, etc. The position measuring device according to this embodiment is referred to as a position measuring device 1a. The same components as those in the first embodiment described above are denoted by the same reference numerals, and the description of the same components and operations may be omitted.

[0115] 10 is a diagram showing an example of the functional configuration of the position measurement device 1a according to this embodiment. The position measurement device 1a includes a position measurement unit 20, a reference position measurement unit 21, a control unit 22, a first image capture unit 23, a reflected light detection unit 24, a communication unit 25, a calculation unit 26a, and a storage unit 27.

[0116] The calculation unit 26 a includes a reference coordinate setting unit 260 , a first correction unit 261 , an incident information acquisition unit 262 , and a second correction unit 263 .

[0117] The incident information acquisition unit 262 acquires incident information from the image of the reflecting element 4 captured by the first imaging unit 23. The incident information is information about the incidence of the measurement light. The incident information includes the incident angle at which the measurement light is incident on the incident surface of the reflecting element 4. The incident information also includes the incident position within the incident surface of the reflecting element 4 at which the measurement light is incident.

[0118] The second correction section 263 corrects the position information acquired by the position measurement section 20 based on the incident information acquired by the incident information acquisition section 262.

[0119] The storage unit 27 stores various types of information. A length measurement value correction map 270 is stored in advance in the storage unit 27 before the position measuring device 1a starts measurement. The length measurement value correction map 270 is information that associates a set of the incident angle at which the measurement light is incident on the incident surface of the reflecting element 4 and the incident position within the incident surface with a correction amount corresponding to an error caused by the reflecting element 4. The error caused by the reflecting element 4 is, for example, an error due to individual differences in the manufacturing of the reflecting element 4.

[0120] The length measurement value correction map 270 may be stored in an external device such as a server. In this case, the incident information acquisition unit 262 acquires the length measurement value correction map 270 from the external device by communicating with the external device via the communication unit 25. Alternatively, the length measurement value correction map 270 may be stored in a storage area included in the second correction unit 263.

[0121] Here, the relationship between the incident angle at which the measurement light is incident on the incident surface of the reflecting element 4 and the optical path length will be described with reference to FIGS. In this embodiment, in order to reduce the change in optical path length due to the incident angle of the measurement light, the rotation center of the prism 41 provided in the reflecting element 4 is changed (shifted) to calculate the optical path length difference.

[0122] Fig. 11 is a diagram showing an example of a cross section of prism 41 provided in reflecting element 4 according to this embodiment. Fig. 11 shows a cross section when prism 41 has a height h1 and a cross section when prism 41 has a height h2. Height h2 is calculated based on equation (1) by correcting height h1 with the refractive index n of the prism.

[0123]

number

[0124] Correcting the rotation center of the prism 41 from height h1 to height h2 is equivalent to converting the rotation center of the prism 41 to a converted position converted to a value in air where no optical path length difference occurs.

[0125] If the optical path length difference is calculated by changing the rotation center of the prism 41 from height h1 to height h2, the optical path length difference with respect to the incident angle can be reduced. Fig. 12 is a diagram showing an example of the optical path length difference with respect to the incident angle according to this embodiment. Fig. 12 shows the optical path length difference with respect to the incident angle when the rotation center of the prism 41 is set to height h1 (no shift), and the optical path length difference with respect to the incident angle when the rotation center of the prism 41 is set to height h2 (shift). Fig. 13 shows a graph in which the graph shown in Fig. 12 is enlarged along the axis of optical path length difference.

[0126] 12 and 13, shifting the rotation center of prism 41 from height h1 to height h2 reduces the optical path length difference compared to not shifting the rotation center of prism 41 from height h1 to height h2. Note that even with a shift, it is not possible to suppress the optical path length difference to zero for all incident angle values. As shown in FIG. 13, even with a shift, the optical path length difference is approximately 50 micrometers at an incident angle of 20 degrees.

[0127] Next, the position measurement process by the position measurement device 1a will be described with reference to Fig. 14. Fig. 14 is a diagram showing an example of the position measurement process according to this embodiment. The position measurement process is executed by the control unit 22.

[0128] The position measurement unit 20 acquires position information of the reflecting element 4 (step S410). The position measurement unit 20 irradiates the incident surface of the reflecting element 4 with measurement light, receives the reflected light, and acquires position information of the reflecting element 4 in three-dimensional space. Details of the position measurement process of step S410 are the same as those of step S10 shown in FIG. 5, and therefore will not be described again.

[0129] The incident information acquisition unit 262 acquires the incident information (step S420). The first imaging unit 23 captures an image of the reflecting element 4 on which the measurement light is incident. The incident information acquisition unit 262 acquires the incident information from the image of the reflecting element 4 captured by the first imaging unit 23.

[0130] 15 to 20, a process in which the incident information acquisition unit 262 acquires incident information from the image of the reflecting element 4 will be described.

[0131] 15 is a diagram showing an example of the front surface of reflective element 4 according to this embodiment. Reflective element 4 includes holder portion 40 and marker portion 42. Marker portion 42 is made up of marker portion 42-1, marker portion 42-2, marker portion 42-3, and marker portion 42-4. The holder portion 40 holds the prism 41 and the marker portion 42. The holder portion 40 has a concentric circular shape when viewed from the front.

[0132] As an example, the marker portions 42 are light-emitting diodes (LEDs). The number of marker portions 42 is not limited to four, and can be any number of three or more, provided that the marker portions 42 are not on the same straight line. Note that instead of LEDs, the marker portions 42 may be provided on the holder portion 40 by painting a predetermined portion of the holder portion 40 with paint. The color of the LED or the color of the paint may be any color as long as the area where the marker portions 42 are provided on the holder portion 40 can be distinguished from other areas. Furthermore, the marker portions 42 are not limited to a plurality of discrete dots. The marker portions 42 can be continuous or intermittent lines, and may be, for example, circular light-emitting portions or paintings that surround the incident surface of the reflective element 4.

[0133] 15, the measurement light emitted from the position measuring device 1 is incident at position P1 on the incident surface of the prism 41 provided in the reflecting element 4. Position P1 is indicated using two-dimensional polar coordinates (R, θ) on the incident surface.

[0134] Fig. 16 is a diagram showing an example of how measurement light L1 is incident on the reflecting element 4 according to this embodiment. Fig. 16 shows cross sections of the holder 40 and the prism 41 provided in the reflecting element 4. In Fig. 16, the measurement light L1 is incident on the prism 41 at an incident angle indicated by angles (α, β). Here, angles α and β are the azimuth angle and the elevation angle, respectively, on the incident plane when three-dimensional spherical coordinates are used.

[0135] 17, 18, 19, and 20 respectively show a photographed image A11, a photographed image A12, a photographed image A13, and a photographed image A14 captured by the coaxial camera 13. In the photographed image A11, a photographed image A12, a photographed image A13, and a photographed image A14, images of the reflecting element 4 are captured when the measurement light is incident on the incident surface of the reflecting element 4 at different positions and angles.

[0136] As described above, the imaging direction of the coaxial camera 13 coincides with the direction of the measurement light. Therefore, in the captured image captured by the coaxial camera 13, the shape of the image of the reflecting element 4 varies depending on the incident angle of the measurement light on the incident surface. The incident information acquisition unit 262 calculates the incident angle based on the shape of the incident surface in the image of the reflecting element 4 captured by the first imaging unit 23. In addition, the incident position of the measurement light on the incident surface is acquired from the image. In this embodiment, the imaging center of the coaxial camera 13 coincides with the optical axis of the measurement light, so the position of the reflecting element 4 is captured differently depending on the incident position of the measurement light on the incident surface.

[0137] For example, the captured image A11 is an image captured by the coaxial camera 13 when the measurement light is incident on the front side of the reflecting element 4. In the captured image A11, the shape of the image of the reflecting element 4 is approximately circular. The captured image A12 is an image captured by the coaxial camera 13 when the measurement light is incident obliquely on the reflecting element 4 with respect to the horizontal direction. In the captured image A12, the shape of the image of the reflecting element 4 is elliptical.

[0138] The captured image A13 is an image captured by the coaxial camera 13 when the measurement light is incident on the front side of the reflecting element 4. In the captured image A13, the shape of the image of the reflecting element 4 is approximately circular, similar to the captured image A11. The incident position of the measurement light is different between the captured image A13 and the captured image A11. Furthermore, the captured image A14 is an image captured by the coaxial camera 13 when the measurement light is incident obliquely on the reflecting element 4 with respect to the vertical direction. In the captured image A14, the shape of the image of the reflecting element 4 is elliptical.

[0139] Returning to FIG. 14, the description of the position measurement process will be continued. The second correction unit 263 corrects the position information of the reflecting element 4 based on the incident information (step S430). Here, the second correction unit 263 reads out the length measurement value correction map 270 from the storage unit 27. The second correction unit 263 reads out, from the length measurement value correction map 270, a correction amount corresponding to the pair of the incident angle and incident position indicated by the incident information acquired by the incident information acquisition unit 262. The second correction unit 263 corrects the position information acquired by the position measurement unit 20 based on the read correction amount.

[0140] As described above, the position information acquired by the position measurement unit 20 includes the distance measured by the distance measurement unit 200. In other words, the correction by the second correction unit 263 corrects the distance measured by the distance measurement unit 200.

[0141] The measurement value correction map 270 will now be described with reference to Fig. 21. Fig. 21 is a diagram showing an example of the measurement value correction map 270 according to this embodiment as a three-dimensional graph. In Fig. 21, the coordinate values ​​of the incident position when the incident angle is 0 degrees for both the azimuth angle and the elevation angle are shown as a curved surface.

[0142] Returning to FIG. 14, the description of the position measurement process will be continued. The control unit 22 transmits the corrected position information to the control system (step S440). With this, the control unit 22 ends the position measurement process.

[0143] (Modification of the second embodiment) The configurations of the holder part and marker part of the reflective element are not limited to those shown in Fig. 15. In this modified example, a case will be described in which the holder part and marker part of the reflective element have configurations that are easily recognized by image recognition.

[0144] 22 is a diagram showing an example of the configuration of reflective element 6 according to this modification. Reflective element 6 includes a holder portion 60, a prism 61, and a marker portion 62. Marker portion 62 is made up of marker portion 62-1, marker portion 62-2, marker portion 62-3, and marker portion 62-4.

[0145] The shape of the holder portion 60 is different from a simple figure so as to be easily recognized by image recognition. The shape of each of the marker portions 62 is concentric. Each of the concentric circles of the marker portion 62 is painted in a color different from the color of the paint on the surface of the holder portion 60. From the viewpoint of ease of recognition in image recognition, it is preferable that the color of the concentric circles of the holder portion 60 has a contrast difference of at least a predetermined value with respect to the color of the paint on the surface of the holder portion 60. For example, the surface of the holder portion 60 is painted yellow, and the concentric circles of the holder portion 60 are painted black.

[0146] (Third embodiment) In the above-described two embodiments, the case where position information is acquired by irradiating measurement light onto one reflecting element 4 is described. In this embodiment, the case where a plurality of reflecting elements 4 are installed on the measurement object and posture information of the measurement object is acquired together with position information of the measurement object is described.

[0147] Fig. 23 is a diagram showing an example of how the position measurement device 1a according to this embodiment measures the position of a measurement object. The position measurement device 1a may be the position measurement device 1 described in the first embodiment. In Fig. 23, the measurement object is, for example, a robot T4. The robot T4 is provided with a plurality of reflecting elements 4a in its movable part.

[0148] 23, the reflecting element 4a is composed of reflecting elements 4a-1, 4a-2, 4a-3, and 4a-4. The reflecting elements 4a-1, 4a-2, 4a-3, and 4a-4 are installed at different positions on the movable part of the robot T4 with known positional relationships. The multiple reflecting elements 4a are preferably installed with a predetermined or greater distance between them.

[0149] 24 is a diagram showing an example of how the position measurement device 1a captures images of each of the multiple reflecting elements 4a. The position measurement device 1a captures images of the multiple reflecting elements 4a using the coaxial camera 13. The irradiation direction movement unit 201 moves (changes) the imaging direction of the coaxial camera 13 so that the multiple reflecting elements 4a are included in the imaging range of the coaxial camera 13. In FIG. 24, the position measurement device 1a captures images of the multiple reflecting elements 4a such that all of the reflecting elements 4a-1, 4a-2, 4a-3, and 4a-4 are included in the imaging range of the coaxial camera 13.

[0150] In this embodiment, the position measurement device 1a acquires position information of each of the reflecting elements 4a in three-dimensional space by moving the irradiation direction shifter 201 and sequentially irradiating the reflecting elements 4a with measurement light based on images of the reflecting elements 4a captured by the coaxial camera 13. Even if the reflected light is temporarily interrupted when the measurement light is shifted between the reflecting elements 4a, the measurement values ​​obtained by the optical comb interferometer 11 are not lost (interrupted). Because the positional relationships between each of the reflecting elements 4a and the positional relationships between the object and the reflecting elements 4a are known, the position and orientation of the object can be acquired from the positional information of the reflecting elements 4a in three-dimensional space. In this way, the position measurement device 1a acquires orientation information of the object based on the distances corresponding to each of the reflecting elements 4 measured by the distance measurement unit 200 and the irradiation directions of the irradiation direction shifter 201 when measuring each of the distances.

[0151] 24 has been described as an example in which all of the plurality of reflecting elements 4a are imaged by the coaxial camera 13, but the present invention is not limited to this. A wide-angle camera may be provided separately from the coaxial camera 13, and the rough positions of the plurality of reflecting elements 4a may be grasped by the wide-angle camera, and then the irradiation direction moving unit 201 may be moved to sequentially image each of the plurality of reflecting elements 4a with the coaxial camera 13, and the measurement light may be irradiated to obtain the position information of the reflecting elements 4a.

[0152] In addition, the position measuring device 1a may calculate the incident angle of the measurement light incident on the multiple reflecting elements 4a using posture information obtained from the position information of the multiple reflecting elements 4a provided on the robot T4, and based on this, correct the position information of the multiple reflecting elements 4a using the method described in the second embodiment.

[0153] At least one of the reflecting elements 4a may be provided as a reference reflecting element on a measurement reference object different from the measurement object. In this case, the position measuring device 1a can acquire position information of the measurement object relative to the measurement reference object based on position information of the reflecting element 4a as the reference reflecting element, even if it does not have a reference position measuring unit 21. Furthermore, if at least three reflecting elements 4a are provided on the measurement object, it can also acquire attitude information of the measurement object.

[0154] The position measuring device 1a may also acquire relative position information of the reflecting element 4a based on the position information of the reference reflecting element. In this case, at least three reference reflecting elements are provided, and the position measuring device 1a acquires position information of the reflecting element 4a relative to a reference point set using the position information of at least three reference reflecting elements.

[0155] The position measuring device 1a may also determine a reference coordinate system including a reference point based on the position information of at least three reference reflecting elements, and acquire the position information of the reflecting element 4a in the reference coordinate system.

[0156] Furthermore, the position measuring device 1a may correct the position information of the reflecting element 4a based on the time change of the position information of the reference reflecting element acquired by the position measuring unit 20.

[0157] As described above, the position measurement device 1a according to the second and third embodiments includes the position measurement unit 20, the imaging unit (first imaging unit 23 in this embodiment), and the incident information acquisition unit 262. The position measurement unit 20 irradiates the incident surface of the reflecting element 4 with measurement light and receives the reflected light to obtain position information of the reflecting element 4 in three-dimensional space. The imaging section (first imaging section 23 in this embodiment) captures an image of the reflecting element 4 onto which the measurement light is incident. The incident information acquisition section 262 acquires incident information about the incidence of the measurement light from the image of the reflecting element 4 captured by the imaging section (first imaging section 23 in this embodiment). The position measuring device 1a corrects the position information acquired by the position measuring unit 20 based on the incident information.

[0158] With this configuration, the position measuring device 1a according to this embodiment can correct the position information of the reflecting element 4 based on the incident information, and therefore can improve the accuracy of the position information compared to when no correction is made.

[0159] The position measuring device 1 a according to this embodiment also includes a position measuring unit 20 . The position measurement unit 20 is a position measurement unit that irradiates the incident surface of the reflecting element 4a with measurement light and receives the reflected light to obtain position information of the reflecting element 4a in three-dimensional space. The position measurement unit 20 includes a distance measurement unit 200 and an irradiation direction movement unit 201 . The distance measurement unit 200 irradiates the reflecting element 4a with measurement light, receives the reflected light, and measures the distance to the reflecting element 4a. The irradiation direction moving unit 201 moves the irradiation direction of the measurement light. The irradiation direction moving unit 201 sequentially moves and irradiates the measurement light toward a plurality of reflecting elements 4a provided on the measurement object (in this embodiment, the robot T4).

[0160] With this configuration, the position measuring device 1a according to this embodiment can obtain position information of multiple reflecting elements 4a based on a single measurement light, so there is no need to provide multiple irradiation units that each irradiate a measurement light, and the position information of multiple reflecting elements 4a can be obtained with a simple configuration.

[0161] (Fourth embodiment) The fourth embodiment of the present invention will be described in detail below with reference to the drawings. In the above embodiments, the position measuring device is described as being installed on a factory floor, a workpiece, etc. In this embodiment, the position measuring device is described as being equipped with a moving device. The position measuring device according to this embodiment is referred to as a mobile position measuring device 1b. The same components as those in the first embodiment described above are denoted by the same reference numerals, and the description of the same components and operations may be omitted.

[0162] 25 is a diagram showing an example of the appearance of a mobile position measurement device 1b according to this embodiment. The mobile position measurement device 1b includes a position measurement device 2 and a mobile device 3. The configuration of the position measurement device 2 is similar to the configuration of either of the position measurement devices 1 and 1a according to the above embodiments, and therefore a description thereof will be omitted.

[0163] The position measuring device 2 is placed on a moving device 3. The moving device 3 is movable. As a result, the position measuring device 2 is transported by the moving device 3. The moving device 3 is equipped with wheels, caterpillar tracks, or the like, and moves automatically. As a result, the moving device 3 can move freely within a factory. One example of the moving device 3 is an automatic guided vehicle (AGV). Note that AGVs are also called unmanned transport robots.

[0164] The moving device 3 may be a transport machine other than an AGV as long as it can move while carrying the position measuring device 2. The moving device 3 may also be configured to move within a predetermined range or course within a factory. For example, the moving device 3 may move along rails or the like provided within the factory.

[0165] The moving device 3 is movable within the factory, and therefore is also movable relative to the reflecting element 4 installed on the robot installed in the factory. Therefore, the mobile position measuring device 1b includes the moving device 3 that is movable relative to the reflecting element 4.

[0166] Since the mobile position measuring device 1b can move within a factory where multiple three-dimensional measuring machines and machine tools are installed, a single mobile position measuring device 1b can sequentially measure the position of an object to be measured in three-dimensional space for multiple three-dimensional measuring machines and machine tools. Furthermore, when the position measuring device 1 described in the first embodiment is used as the position measuring device 2, the reference position measuring unit 21 can measure the position of the object to be measured using the measurement reference object as a reference, so even if the position of the mobile position measuring device 1b changes due to movement, the position of the object to be measured relative to the measurement reference object can be measured with high accuracy. Furthermore, when the position measuring device 1a described in the second embodiment is used as the position measuring device 2, even if the incident position and angle of the measurement light on the reflecting element 4 installed on the object to be measured change due to movement, the error that occurs depending on the incident position and incident angle can be corrected, so that the position of the object to be measured relative to the measurement reference object can be measured with high accuracy.

[0167] Note that parts of the position measuring devices 1, 1a, and mobile position measuring device 1b in the above-described embodiments, such as the control unit 22 and the calculation unit 26, 26a, may be implemented by a computer. In this case, a program for implementing the control functions may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein refers to the computer system built into the position measuring devices 1, 1a, and mobile position measuring device 1b, including hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, the term "computer-readable recording medium" may also include devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, or devices that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as the server or client in such cases. Furthermore, the above program may be one that realizes part of the functions described above, or may be one that can realize the functions described above in combination with a program already recorded in the computer system. Furthermore, part or all of the position measurement devices 1, 1a, and mobile position measurement device 1b in the above-described embodiments may be realized as integrated circuits such as LSI (Large Scale Integration). Each functional block of the position measurement devices 1, 1a, and mobile position measurement device 1b may be individually implemented as a processor, or part or all of them may be integrated into a processor. Furthermore, the integrated circuit implementation method is not limited to LSI, and may be implemented using a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit implementation technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used.

[0168] One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0169] 1, 1a... position measuring device, 1b... mobile position measuring device, 4... reflecting element, 4, 5... reference reflecting element, 20... position measuring section, 21... reference position measuring section

Claims

1. a reference position measurement unit that irradiates at least one reference reflecting element with reference measurement light, receives the reference reflected light reflected by the reference reflecting element, and acquires position information of the reference reflecting element in three-dimensional space; a position measurement unit that irradiates a measurement light onto a reflecting element whose position can be changed relative to the reference reflecting element, receives the light reflected by the reflecting element, and acquires position information of the reflecting element in three-dimensional space; Equipped with A position measuring device that corrects the position information of the reflecting element measured by the position measuring unit using a change over time in the position information of the reference reflecting element acquired by the reference position measuring unit.

2. Obtaining relative position information of the reflecting element based on the position information of the reference reflecting element 2. The position measuring device according to claim 1.

3. a plurality of the reference position measurement units; The plurality of reference position measuring units each acquire position information of a different reference reflecting element.

2. The position measuring device according to claim 1.

4. the reference position measurement unit acquires position information of at least three of the reference reflecting elements; Acquiring position information of the reflecting element with respect to a reference set using at least three pieces of position information.

4. The position measuring device according to claim 3.

5. the reference position measurement unit acquires position information of at least three of the reference reflecting elements; A reference coordinate system is defined using at least three pieces of position information, and position information of the reflective element in the reference coordinate system is obtained.

5. The position measuring device according to claim 4.

6. The correction includes arranging the reflecting element at a predetermined position in the reference coordinate system, and matching position information obtained by measurement by the position measurement unit with position information of the predetermined position in the reference coordinate system.

6. The position measuring device according to claim 5.

7. The correction includes matching the position information acquired by the position measurement unit with the position information acquired by the reference position measurement unit for the same reflecting element.

2. The position measuring device according to claim 1.

8. The correction includes correcting fluctuations in the position information of the reflecting element over time.

2. The position measuring device according to claim 1.

9. The correction includes correcting an error in the position information of the reflecting element caused by the temperature and air pressure of a space in which the reflecting element and the reference reflecting element are arranged, based on the position information of the reference reflecting element acquired by the reference position measurement unit.

2. The position measuring device according to claim 1.

10. The position measurement unit a distance measurement unit that irradiates the reflecting element with the measurement light and receives the reflected light to measure the distance to the reflecting element; an irradiation direction moving unit that moves the irradiation direction of the measurement light; an irradiation direction measurement unit that measures the irradiation direction, The position information of the reflecting element in the three-dimensional space is acquired from the distance measured by the distance measurement unit and the irradiation direction measured by the irradiation direction measurement unit.

2. The position measuring device according to claim 1.

11. The reference position measurement unit a reference distance measurement unit that irradiates the reference reflecting element with the reference measurement light and receives the reference reflected light to measure the distance to the reference reflecting element; a reference irradiation direction measurement unit for measuring the irradiation direction of the reference measurement light, The position information of the reference reflecting element in the three-dimensional space is acquired from the distance to the reference reflecting element measured by the reference distance measuring unit and the irradiation direction of the reference measurement light measured by the reference irradiation direction measuring unit.

11. The position measuring device according to claim 10.

12. The measurement light of the distance measurement unit and the reference measurement light of the reference distance measurement unit are supplied by splitting from the same light source.

12. The position measuring device according to claim 11.

13. a reflected light detection unit that detects the reflected light, the reflected light detection unit detects movement of the reflected light that moves in accordance with movement of the reflecting element, The irradiation direction moving unit moves the irradiation direction in accordance with the movement of the reflected light detected by the reflected light detecting unit.

11. The position measuring device according to claim 10.

14. The reflected light detector is an imaging device that captures an image of the reflecting element or a photoelectric detection device that detects the amount of reflected light.

14. The position measuring device according to claim 13.

15. The optical path of the distance measuring unit through which the measurement light passes and the optical path of the reflected light detecting unit through which the reflected light passes are partially common.

14. The position measuring device according to claim 13.

16. The reflected light detector includes an imaging unit that is different from the reflected light detector, and the imaging unit captures an image of the reflecting element.

14. The position measuring device according to claim 13.

17. The optical path of the distance measurement unit through which the measurement light passes, the optical path of the reflected light detection unit through which the reflected light passes, and the optical path of the imaging unit share a part in common.

17. The position measuring device according to claim 16.

18. The reflecting element is provided on a movable measurement object, and the reference reflecting element is provided on a measurement reference object different from the measurement object.

2. The position measuring device according to claim 1.

19. The measurement object and the measurement reference object constitute a single device, and an apparatus coordinate system serving as a reference for position information of the measurement object in the single device is determined based on position information of the reference reflecting element acquired by the reference position measurement unit.

19. The position measuring device according to claim 18.

20. a moving device that is movable relative to the reflecting element; 2. The position measuring device according to claim 1.

21. The position measurement unit: a distance measurement unit that irradiates the reflecting element with the measurement light and receives the reflected light to measure the distance to the reflecting element; and an irradiation direction movement unit that moves the irradiation direction of the measurement light, The irradiation direction moving unit sequentially moves and irradiates the measurement light toward the plurality of reflecting elements provided on the measurement object and the reflecting element provided as a reference reflecting element on a measurement object different from the measurement object. A position measuring device according to any one of claims 1 to 9 and claims 18 to 20.

22. At least three reference reflecting elements are provided, and position information of the reflecting elements is acquired with respect to a reference point set using position information of the at least three reference reflecting elements.

22. The position measuring device according to claim 21.

23. A reference coordinate system including the reference point is defined based on position information of at least three of the reference reflecting elements, and position information of the reflecting elements in the reference coordinate system is obtained.

23. The position measuring device of claim 22.

24. Irradiating at least one reference reflecting element with reference measurement light and receiving reference reflected light reflected by the reference reflecting element to obtain position information of the reference reflecting element in three-dimensional space; Irradiating a measurement light onto a reflecting element whose position can be changed relative to the reference reflecting element, and receiving the light reflected by the reflecting element to acquire position information of the reflecting element in three-dimensional space; and correcting the position information of the reflecting element using a change over time in the position information of the reference reflecting element.

25. acquiring relative position information of the reflective element based on position information of the reference reflective element; 25. The method of claim 24.

26. acquiring position information of a plurality of the reference reflective elements, each of which is different from the other; the correction includes correcting position information of the reflecting element using position information of the plurality of reference reflecting elements acquired; 25. The method of claim 24.

27. The position information of the plurality of reference reflective elements is at least three, setting a reference using the acquired at least three pieces of location information; The correction includes acquiring position information of the reflecting element with respect to the set reference.

27. The method of claim 26.

28. the correction includes determining a reference coordinate system using the acquired at least three pieces of position information and acquiring position information of the reflective element in the reference coordinate system.

28. The method of claim 27.

29. the correction includes correcting an error in position information of the reflecting element caused by temperature and air pressure in a space in which the reflecting element and the reference reflecting element are arranged, based on position information of the reference reflecting element.

25. The method of claim 24.

30. Moving the irradiation direction of the measurement light toward the plurality of reflective elements provided on the measurement object and the reflective element provided as a reference reflective element on a measurement object different from the measurement object; irradiating the reflecting element with the measurement light and receiving the reflected light to measure the distance to the reflecting element; Including, The moving and measuring are sequentially performed for each of the plurality of reflecting elements provided on the measurement object.

30. A position measurement method according to any one of claims 24 to 29.

Images