JP2013117417A - Measurement auxiliary tool, laser tracker, and diameter measurement method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement auxiliary tool for setting a target even with respect to a measurement object positioned in a place far from a laser tracker, and measuring the spatial coordinates of the surface of the measurement object on the opposite side viewed from the laser tracker without failing in tracking.SOLUTION: A measurement auxiliary tool 20A includes: an upper end surface contact part 21 which is disposed so as to be brought into contact with the upper end surface of a measurement object W; a peripheral surface contact part 22 which is disposed so as to be extended downward from the upper end surface contact part 21, and so as to be brought into contact with the peripheral surface of the measurement object W; a first target installation part 23 which is disposed above the upper end surface contact part 21, therein a target Tg is installed for measuring the measurement object; and a second target installation part 24 which is disposed above the upper end surface contact part 21 at an already known distance from the first target installation part 23, therein the target Tg is installed for measuring an absolute distance from the laser tracker 1 to the target Tg installed at the first target installation part 23.

Description

  The present invention relates to a measurement auxiliary instrument used auxiliary in measuring the spatial coordinates of an object such as a product, a building, or a natural object in the industrial and measurement fields, a laser tracker for performing the above measurement, and these. The present invention relates to a diameter measuring method.

Laser tracking technology that controls the direction of the laser beam used as a guide with a biaxial motor to follow a moving target to obtain spatial coordinates (three-dimensional position information) of the target has long been known. In this laser tracking technology, it is possible to know the spatial direction (angle) of a moving target using a biaxial encoder attached to each motor. The target is generally a retro-reflector or simply a reflector that uses three mirrors orthogonal to each other. In any case, the reflector can return light in the incident direction.
Further, a technique for measuring a distance with a laser has been established. For example, a laser interferometer can measure a distance of several meters with a resolution of a nanometer unit.

  A device that combines the above two technologies is a laser tracker (for example, Patent Document 1), which measures the distance from the device to the target and the spatial angle with a laser interferometer and an encoder, respectively. The spatial position of the target with reference to the apparatus is specified from the measured value. Attempts have been made to measure the diameters of the inner and outer rings of the bearing using this laser tracker. The measurement is performed according to the following procedure.

(1) A laser tracker is installed in the vicinity of an object to be measured (bearing inner ring, outer ring, etc.).
(2) The target is brought into contact with the outer peripheral surface or inner peripheral surface of the measurement object.
(3) Laser light is emitted from the laser tracker toward the target, and the light reflected by the target is received again by the laser tracker. The spatial coordinates (three-dimensional position information) of the target are obtained from the encoder value and the laser interferometer value at this time.
(4) The above operations (2) and (3) are repeated at least three times to obtain three or more spatial coordinates, and the diameter of the measurement object is calculated therefrom.

JP 2009-2728 A

  However, depending on the shape of the measurement object, the target may not be stably installed on the measurement object. In addition, when the target is on the opposite side (back side) of the measurement object as viewed from the laser tracker, the laser beam emitted from the laser tracker is blocked by the measurement object and does not reach the target, so that measurement cannot be performed. That is, as viewed from the laser tracker, the spatial coordinates of the front surface of the measurement object can be measured, but the spatial coordinates of the opposite surface cannot be measured. Therefore, the applicant of this application proposes a measurement aid that can be used in combination with a laser tracker so that the target can be stably placed on the measurement object and the spatial coordinates of the opposite surface can also be measured. (Japanese Patent Application No. 2011-38367).

  As shown in FIGS. 9 to 11, the proposed measurement auxiliary instrument 40 is provided with an upper end surface contact portion 41 that is brought into contact with the upper end surface of the measurement object W and a measurement target that extends downward from the upper end surface contact portion 41. The peripheral surface contact part 42 made to contact the peripheral surface of the thing W, and the target installation part 43 provided in the upper part of the said upper end surface contact part 41 and in which the target Tg is installed are provided. The center of the target installation portion 43 is located on the central axis O of the circumferential surface contact portion 42. The target installation portion 43 has a conical recess 43a formed on the upper surface, and the target Tg can be accurately positioned and installed simply by placing the target Tg on the recess 43a.

  By the way, the spatial coordinate is a coordinate expressed by an absolute distance from a point A (reflection point of the mirror 13) where the laser beam Lb is emitted from the laser tracker 1 and an angle in a biaxial direction viewed from the point A. That is. However, since the laser interference type length measuring device 2b (FIG. 9) provided in the laser tracker 1 is not an absolute distance meter, the absolute distance from the point A to the target Tg installed on the measurement object W is directly measured. I can't do it. Therefore, as shown in FIG. 9, for example, the reference position member 45 is installed at a position at a known distance b from the point A such as the upper surface of the laser tracker 1, and the position coordinates (distance) of the target Tg installed on the reference position member 45. Value and angle value) as a reference, the absolute distance to the target Tg placed on the measuring object W is calculated.

  The principle of calculating the absolute distance will be described with reference to FIG. Although it is actually a 3D space story, it will be described as 2D for simplicity. The position coordinate distance value obtained by measuring the target Tg installed on the reference position member 45 by the laser interference type length measuring device 2b is x, and the position coordinate obtained by measuring the target Tg installed on the target installation unit 43 of the measurement auxiliary instrument 40. If the distance value of y is y, the absolute distance z from the point A to the target Tg installed in the target installation unit 43 is represented by z = (y−x) + b.

Actual measurement is performed as follows.
(1) The target Tg is placed on the reference position member 45, and its position coordinates (distance value x, angle value θ1, angle value ψ1) are acquired.
(2) Thereafter, the operator moves the target Tg while tracking the target Tg with the laser light Lb from the reference position member 45 to the target setting unit 43 of the measurement auxiliary instrument 40 installed on the measurement target W. And the position coordinate (distance value y, angle value (theta) 2, angle value (psi) 2) of the target Tg installed in the target installation part 43 is acquired.
(3) Using the distance values x and y of the two positions of the reference position member 45 and the target setting portion 43 and the distance b from the point A to the reference position member 45, the target setting portion of the measurement auxiliary instrument 40 from the point A The absolute distance z to the target Tg installed at 43 is calculated. From the absolute distance z thus calculated and the difference between the angle values θ1, ψ1 acquired in (1) and the angle values θ2, ψ2 acquired in (2), the spatial coordinates of the target Tg installed in the target installation unit 43. (3D position information) is determined. In addition,
(4) The above operations (2) and (3) are repeated at least three times to obtain three or more spatial coordinates, and the diameter of the measurement object is calculated therefrom.

  In the above measurement method, even when the distance from the reference position member 45 to the target installation portion 43 of the measurement object W is long, tracking of the target Tg by the laser beam Lb must be continued while the target Tg is moved between the two. Don't be. The operator is required to move the target Tg with the mirror reflection surface of the target Tg always directed to the laser tracker 1. However, there is a high possibility that tracking will fail because the direction of the mirror reflecting surface is mistakenly removed from the laser tracker 1 or the laser beam Lb is blocked by a foreign object or the like while the target Tg is moving. . If tracking fails on the way, it is necessary to start over from the beginning.

An object of the present invention is to enable a target to be placed on a measurement object located far from a laser tracker without failing tracking, and to measure the spatial coordinates of the opposite surface when viewed from the laser tracker. It is to provide a measurement aid that makes it possible.
Another object of the present invention is to provide a laser tracker that can easily and accurately measure the diameter of an object to be measured using the measurement auxiliary instrument.
Another object of the present invention is to provide a diameter measuring method capable of easily and accurately measuring a diameter of a circular measuring object.

The measurement assisting instrument of each of the following inventions is used as an assist for a laser tracker that irradiates a target with a laser beam on a measurement object and obtains the spatial coordinates of the target while tracking the position of the target from the reflected light.
The first measurement auxiliary instrument according to the present invention includes an upper end surface contact portion that contacts the upper end surface of the measurement object, and a peripheral surface contact that extends downward from the upper end surface contact portion and contacts the peripheral surface of the measurement object. From the first target installation part at the upper part of the upper end surface contact part, and a first target installation part provided at the upper part of the upper end surface contact part. A second target installation unit provided at a known distance for calculating an absolute distance from the laser tracker to a target installed in the first target installation unit. .

  The measurement auxiliary instrument having this configuration is installed by bringing the upper end surface contact portion into contact with the upper end surface of the measurement object, and bringing the peripheral surface contact portion into contact with a predetermined height position on the peripheral surface of the measurement object. In this state, once the target is installed on the second target installation unit, the target is moved from the second target installation unit to the first target installation unit while tracking the target with the laser tracker. The tracking of the target by the laser tracker is performed by irradiating the target with laser light and receiving the reflected light to confirm the position of the target. Since the first target installation unit and the second target installation unit are at a distance close to each other on the measurement auxiliary instrument, the target can be moved while being easily tracked.

  And the distance value in the position coordinate of the target acquired in the 2nd target installation part, the distance value in the position coordinate of the target acquired in the 1st target installation part, and the 1st and 2nd target which are known values The absolute distance from the laser tracker to the target installed in the first target installation unit is calculated from the distance between the installation units. The length measuring device provided in the laser tracker is, for example, a laser interference type length measuring device, and does not measure the absolute distance from the laser tracker to the target. Therefore, the absolute distance is obtained by the above method.

  Furthermore, the spatial coordinates of the target installed in the first target installation unit are obtained from the calculated absolute distance and the angle information in the biaxial direction between the first and second target installation units. The “spatial coordinates” referred to here are coordinates represented by the absolute distance from the laser tracker and the angle in the biaxial direction viewed from the laser tracker. Moreover, since the positional relationship between the first target installation part and the peripheral surface contact part is known in advance, the peripheral surface contact on the peripheral surface of the measurement object is determined from the spatial coordinates of the target installed in the first target installation part. The spatial coordinates of the contact point of the part are obtained.

  Since the target is installed in the first and second target installation units located above the upper end surface contact portion that is brought into contact with the upper end surface of the measurement object, measurement is performed on the opposite side of the measurement object as viewed from the laser tracker. Even when the auxiliary instrument is located, the laser light emitted from the laser tracker strikes the target without being blocked by the measurement object. For this reason, the laser tracker can measure not only the surface on the near side but also the spatial coordinates of the opposite surface as viewed from the laser tracker.

  The second measurement auxiliary instrument according to the present invention includes an upper end surface contact portion that makes contact with the upper end surface of the measurement object, and a peripheral surface contact that extends downward from the upper end surface contact portion and makes contact with the peripheral surface of the measurement object. And a target installation unit on which the target is installed, the target installation unit, a measurement position for measuring a measurement object, and a known distance from the measurement position. And a guide member that is movably guided between a reference position for calculating an absolute distance.

  In the measurement auxiliary instrument of this configuration, the upper end surface contact portion is brought into contact with the upper end surface of the measurement object, and the peripheral surface contact portion is brought into contact with a predetermined height position on the peripheral surface of the measurement object, as described above. Installed. In this state, after the target is set on the target setting unit located at the reference position, the target setting unit is moved to the measurement position while tracking the target with the laser tracker. Since the target is moved together with the target installation portion by guidance by the guide member, the target can be easily moved.

  Then, from the distance value of the position coordinates of the target acquired at the reference position, the distance value of the position coordinates of the target acquired at the measurement position, and the distance between the first and second target installation parts that are known values, The absolute distance from the tracker to the target installed in the first target installation unit is calculated. The calculation method is the same as described above. The method for obtaining the spatial coordinates of the measurement object is the same as described above.

  In this invention, the said guide member guides the said target installation part so that it can move to an up-down direction, The upper end of the movement range may be made into the said reference position, and a lower end may be made into the said measurement position.

As described above, when the target installation unit is movably provided, it is preferable to provide a movement drive source that moves the target installation unit between the reference position and the measurement position.
When the movement drive source is provided, the target does not have to be moved manually, so that the measurement work is facilitated.

  The laser tracker according to the present invention includes a laser light source that emits a laser beam used for measuring a distance to the target and detecting an angular position, the same optical axis as the laser beam emitted from the laser light source, and the laser beam. And a light emitting source that emits light that is used only for detecting an angular position with respect to the target.

  In order to start tracking the target, it is necessary to apply tracking light such as laser light to the target with a certain degree of accuracy. However, if the beam diameter of the tracking light is small, it is difficult to accurately apply the light to the target. Therefore, apart from the laser light source used for measuring the distance to the target and detecting the angular position, a light emitting source for emitting light having a larger beam diameter than the laser light emitted from the laser light source is provided. The target is discovered by the light emitted from the source. Thereby, target tracking can be easily started.

In the laser tracker according to the present invention, the light emitting source may be one using a semiconductor laser, or one using LED illumination.
Since the light emission source used only at the start of tracking is not required to have the tracking accuracy as much as the laser light source, it can be one using a relatively inexpensive semiconductor laser or one using LED illumination. Thereby, cost reduction can be realized.

  In the first diameter measuring method according to the present invention, the measurement of the measurement object having a cylindrical measurement target peripheral surface on the outer periphery or the inner periphery using any one of the first measurement auxiliary instrument and each of the laser trackers described above. A method for measuring a diameter of a target peripheral surface, wherein the laser tracker is installed in the vicinity of the measurement object, and the measurement auxiliary instrument is contacted with the upper end surface of the measurement object by the upper end surface contact portion, And the process of installing so that the above-mentioned peripheral surface contact part may contact the above-mentioned measurement object peripheral surface of a measurement object, the process of installing the above-mentioned target in the above-mentioned 2nd target installation part, and tracking the above-mentioned target with the above-mentioned laser tracker The laser tracker acquires the process of moving to the first target setting unit while moving and the spatial coordinates of the target installed in the first target setting unit. The process of acquiring the spatial coordinates of the target is repeated three or more times while changing the circumferential position of the measurement auxiliary instrument with respect to the measurement object, and the measurement target circumference is obtained from the acquired three or more spatial coordinates. The diameter of the surface is calculated.

  By performing each of the above processes, as described in the first measurement auxiliary instrument, the spatial coordinates of the target installed in the first target installation unit is obtained by the laser tracker, and further, from the spatial coordinates of the target, The spatial coordinates of the contact location of the peripheral surface contact portion on the peripheral surface of the measurement object are obtained. By changing the circumferential position of the measurement auxiliary tool with respect to the measurement object and obtaining three or more spatial coordinates of the contact location, the diameter of the measurement target circumferential surface can be derived by calculation.

  The second diameter measuring method according to the present invention uses the second measurement auxiliary instrument and any of the above laser trackers to measure the measurement object having a cylindrical measurement target peripheral surface on the outer periphery or the inner periphery. A method for measuring a diameter of a target peripheral surface, wherein the laser tracker is installed in the vicinity of the measurement object, and the measurement auxiliary instrument is contacted with the upper end surface of the measurement object by the upper end surface contact portion, And the step of installing the peripheral surface contact portion so as to contact the measurement target peripheral surface of the measurement object, the step of installing the target on the target installation portion located at the reference position, and the target as the laser A process of moving the target installation unit from the reference position to the measurement position while tracking with a tracker, and installed in the target installation unit located at the measurement position The process of acquiring the spatial coordinates of the target with the laser tracker was performed, and the process of acquiring the spatial coordinates of the target was repeated three times or more by changing the circumferential position of the measurement auxiliary instrument with respect to the measurement object. The diameter of the measurement target peripheral surface is calculated from three or more spatial coordinates.

  Also in this case, as described in the second measurement auxiliary instrument, the spatial coordinates of the target installed in the target installation unit located at the measurement position are obtained by the laser tracker as described in the second measurement auxiliary instrument. From the spatial coordinates of the target, the spatial coordinates of the contact location of the peripheral surface contact portion on the peripheral surface of the measurement object are obtained. By changing the circumferential position of the measurement auxiliary tool with respect to the measurement object and obtaining three or more spatial coordinates of the contact location, the diameter of the measurement target circumferential surface can be derived by calculation.

  The first measurement assisting instrument of the present invention is used as an assist for a laser tracker that irradiates a target placed on a measurement object with a laser beam and obtains the spatial coordinates of the target while tracking the position of the target from the reflected light. An upper end surface contact portion that contacts the upper end surface of the measurement object, a peripheral surface contact portion that extends downward from the upper end surface contact portion and contacts the peripheral surface of the measurement object, and the upper end surface contact Provided at the upper part of the unit, provided at a known distance from the first target installation part at the upper part of the first target installation part where the target is installed for measurement object measurement and the upper end surface contact part, A second target installation unit on which the target is installed for calculating an absolute distance from the laser tracker to a target installed on the first target installation unit. Therefore, it is possible to set a target even for a measurement object far away from the laser tracker without failing in tracking, and to measure the spatial coordinates of the opposite surface when viewed from the laser tracker. is there.

  The second measurement auxiliary instrument according to the present invention is used as an auxiliary to a laser tracker that irradiates a target with a laser beam on a measurement object and obtains the spatial coordinates of the target while tracking the position of the target from the reflected light. An upper end surface contact portion that contacts the upper end surface of the measurement object, a peripheral surface contact portion that extends downward from the upper end surface contact portion and contacts the peripheral surface of the measurement object, and the upper end surface contact A target installation unit on which the target is installed, a target installation unit, a measurement position for measuring an object to be measured, and a reference position for calculating an absolute distance at a known distance from the measurement position And a guide member that can move freely between and the target, so that the target can be set without failing to track even the measurement object far from the laser tracker. Rukoto can, it is possible to measure the spatial coordinates of the opposite surface as viewed from the laser tracker.

  The laser tracker according to the present invention includes a laser light source that emits a laser beam used for measuring a distance to the target and detecting an angular position, the same optical axis as the laser beam emitted from the laser light source, and the laser beam. Since the light beam diameter is larger and the light emitting source for emitting the light used only for detecting the angular position with respect to the target is provided, the tracking operation can be easily started.

  The first diameter measuring method of the present invention uses the first measurement auxiliary instrument and any one of the laser trackers described above, and the measurement target of the measurement target having a cylindrical measurement target peripheral surface on the outer periphery or the inner periphery. A method for measuring a diameter of a peripheral surface, wherein the laser tracker is installed in the vicinity of an object to be measured, and the measurement auxiliary instrument is contacted with the upper end surface contact portion of the object to be measured, and The process of installing the peripheral surface contact portion so as to contact the measurement target peripheral surface of the measurement object, the process of installing the target on the second target installation portion, and tracking the target with the laser tracker The process of moving to the first target installation unit while acquiring the spatial coordinates of the target installed in the first target installation unit by the laser tracker And the process of obtaining the spatial coordinates of the target is repeated three or more times while changing the circumferential position of the measurement auxiliary instrument with respect to the measurement object, and the diameter of the measurement target circumferential surface from the obtained three or more spatial coordinates Therefore, it is possible to easily and accurately measure the diameter of the circular measurement object.

  The second diameter measuring method of the present invention uses the second measurement auxiliary instrument and any one of the above laser trackers to measure the measurement target of the measurement target having a cylindrical measurement target peripheral surface on the outer periphery or the inner periphery. A method for measuring a diameter of a peripheral surface, wherein the laser tracker is installed in the vicinity of an object to be measured, and the measurement auxiliary instrument is contacted with the upper end surface contact portion of the object to be measured, and A step of installing the peripheral surface contact portion so as to contact the measurement target peripheral surface of the measurement object; a step of installing the target on the target installation portion located at the reference position; and And moving the target installation unit from the reference position to the measurement position while tracking, and the target installed in the target installation unit located at the measurement position. And the process of acquiring the spatial coordinates of the target by the laser tracker, and the process of acquiring the spatial coordinates of the target was repeated three times or more by changing the circumferential position of the measurement auxiliary device with respect to the measurement object. Since the diameter of the circumferential surface of the measurement object is calculated from three or more spatial coordinates, the diameter of the circular measurement object can be measured easily and accurately.

1 is a perspective view of a measurement auxiliary instrument according to an embodiment of the present invention and a laser tracker used in combination with the measurement auxiliary instrument. It is a figure which shows the use condition of the measurement auxiliary instrument and the laser tracker. It is explanatory drawing which shows the principle of the measurement of the spatial coordinate by the same measurement auxiliary instrument and the same laser tracker. It is a figure which shows the method of measuring the outer diameter of the measuring object by the laser tracker. It is a perspective view of the measurement auxiliary instrument concerning a different embodiment of this invention. It is a perspective view of the measurement auxiliary instrument concerning further another embodiment of this invention. It is a perspective view of the measurement auxiliary instrument concerning further another embodiment of this invention. It is a perspective view of a laser tracker etc. concerning a different embodiment of this invention. It is a perspective view of the conventional laser tracker and a measuring object. It is a perspective view of the conventional measurement auxiliary instrument. It is explanatory drawing which shows the principle of the measurement of the conventional spatial coordinate.

  FIG. 1 is a diagram showing a usage state of a measurement auxiliary instrument according to one embodiment of the present invention. The measurement auxiliary instrument 20A is an instrument used as an auxiliary to the laser tracker 1A that measures the spatial coordinates of the measurement target W. In particular, when the measurement target W is circular, the diameter of the measurement target W is measured. It is suitable for doing.

  First, the laser tracker 1A will be described. The laser tracker 1A is a device that follows the movement of the target Tg installed on the measurement target W and obtains the spatial coordinates of the measurement target W. As the target Tg, for example, a spherical retro reflector is used. However, it is not limited to a spherical retro reflector.

  The laser tracker 1A mainly includes a laser light source 2a, a length measuring device 2b, a light receiving unit 3, an angle adjusting unit 4, a control unit 5, and a calculation unit 6.

  The laser light source 2a is for irradiating the target Tg with the laser light Lb. For example, a He—Ne laser is used. The length measuring device 2b detects a distance value to the target Tg using the laser beam Lb reflected by the target Tg, and for example, a laser interference type is used. The laser interference type length measuring device 2b does not measure the absolute distance from the laser tracker 1 to the target Tg, but measures the displacement amount of the target Tg using the distance value. In this example, the laser light source 2 a and the length measuring device 2 b are integrated to constitute the laser length measuring device 2. The laser length measuring device 2 is accommodated in a cylindrical casing 7.

  The light receiving unit 3 recognizes the position information of the reflected light of the laser light Lb, and is configured by, for example, a semiconductor position detecting element (abbreviated as PSD) or a quadrant photodiode. The position information of the reflected light represents the displacement amount of the laser spot in the two orthogonal directions on the light receiving unit 3. The light receiving unit 3 is also accommodated in the casing 7.

  The angle adjusting unit 4 includes a half mirror 8, a θ-axis motor 9, a θ-axis encoder 10, a ψ-axis motor 11, a ψ-axis encoder 12, and a mirror 13. The θ axis in the θ axis motor 9 and the ψ axis in the ψ axis motor 11 are orthogonal to each other. The θ axis is disposed in parallel with the axis of the casing 7.

  A rotating body 14 is supported on the upper end of the casing 7 so as to be angularly displaceable about the θ axis. The rotating body 14 is rotationally driven by the θ-axis motor 9. The angular displacement of the rotating body 14 is detected by the θ-axis encoder 10. The ψ-axis motor 11 and the ψ-axis encoder 12 are supported on the upper part of the rotating body 14 via a concave frame 15. The mirror 13 is supported on a rotating shaft 11 that is rotated by a ψ-axis motor 11. The mirror 13 is angularly displaced by the rotational drive of the ψ-axis motor 11. The angular displacement of the mirror 13 is detected by the ψ-axis encoder 12. Note that a hole h through which laser light (including reflected light) Lb passes is formed in the upper end portion of the casing 7, the rotating body 14, and the frame 15.

  The laser light Lb emitted from the laser light source 2a passes through the half mirror 8, is reflected by the mirror 13, and then reaches the target Tg. The laser light Lb reflected from the target Tg, that is, the reflected light passes through substantially the same path, returns to the irradiation source laser tracker 1, is reflected by the half mirror 8 in the casing 7, and reaches the light receiving unit 3.

  Based on the signal from the light receiving unit 3, the control means 5 controls each driver of the θ-axis motor 9 and the ψ-axis motor 11 so that the reflected light reaching the light receiving unit 3 always returns to the center of the light receiving unit 3. (Not shown). Based on this command, the θ-axis motor 9 and the ψ-axis motor 11 cause the mirror 13 to be angularly displaced about the θ-axis and the ψ-axis that are orthogonal to each other. As a result, the mirror 13 is always directed in an appropriate direction.

  A part of the laser beam Lb returned to the laser tracker 1 enters the length measuring device 2b without being reflected by the half mirror 8. The length measuring device 2b receives the reflected light of the laser light Lb, and acquires the distance value of the target Tb from the laser light Lb projected by the laser light source 2a and the received reflected light.

  The calculation means 6 calculates the spatial coordinates (three-dimensional position) of the target Tg from the distance values before and after the movement of the target Tb acquired by the length measuring device 2b and the measured values of the θ-axis encoder 10 and the ψ-axis encoder 12. Information).

  Next, the measurement auxiliary instrument 20A will be described with reference to FIGS. The measurement auxiliary instrument 20A includes an upper end surface contact portion 21, a peripheral surface contact portion 22, and first and second target installation portions 23 and 24.

  The upper end surface contact portion 21 is a part that brings the bottom surface 21 into contact with the upper end surface of the measurement object W. In this example, the planar shape is an oval plate shape. The peripheral surface contact portion 22 is a portion that brings the outer peripheral surface 22 a into contact with the peripheral surface of the measuring object W, and has a disk shape smaller in diameter than the upper end surface contact portion 21. The peripheral surface contact portion 22 is provided at the lower end of the shaft 25 extending downward from the upper end surface contact portion 21.

  The first target installation part 23 is constituted by a part of the upper end surface contact part 21 and has a conical recess 23a that opens upward. The center of the axis is the same as the center of the first target installation portion 23 and the center of the peripheral surface contact portion 22. That is, the center of the first target installation part 23 is located on the central axis O of the circumferential surface contact part 22. The second target installation portion 24 is fixed to the upper surface of the upper end surface contact portion 21 and has a conical recess 24a that opens upward. Thus, since the 1st and 2nd target installation parts 23 and 24 are the shapes which have conical recessed part 23a, 24a, the target Tg can be correctly positioned and installed only by mounting the target Tg. The distance c between the first target installation unit 23 and the second target installation unit 24 is known.

  A diameter measuring method for measuring the diameter of the circular measuring object W using the laser tracker 1 and the measurement auxiliary instrument 20A will be described. As shown in FIG. 2, the measurement object W is, for example, a bearing or an inner ring or an outer ring that is a bearing ring of the bearing, and measures an outer diameter ΦD2. The measurement is performed by the following method (see FIG. 1).

(1) The laser tracker 1 is installed in the vicinity of the measurement object W. (2) The measurement auxiliary instrument 20A is contacted with the bottom surface 21a of the upper end surface contact portion 21 and the upper surface Wa of the measurement object W. It installs so that the outer peripheral surface 22a of the part 22 may contact the outer peripheral surface Wb of the measuring object W.
(3) The target Tg is installed in the second target installation unit 24 of the measurement auxiliary instrument 20A. At this time, the operator does not need to track the target Tg from the laser tracker 1 to the measurement target W with the laser beam Lb.
(4) Irradiate the laser beam Lb toward the target Tg and start tracking.
(5) The position coordinates (distance value u, angle values θ1, ψ1) of the target Tg in the second target installation unit 24 are acquired.
(6) The target Tg is moved from the second target installation unit 24 to the first target installation unit 23, and the position coordinates (distance value v, angle values θ2, ψ2) of the target Tg in the first target installation unit 23 To get. The target Tg is moved while being tracked by the laser beam Lb. However, since the distance between the second target installation unit 24 and the first target installation unit 23 is very short, there is very little possibility of tracking failure.
(7) From the distance values u and v of the position coordinates acquired in the above (5) and (6) and the distance c between the first target installation unit 23 and the second target installation unit 24, point A (mirror) The absolute distance w from 13) to the target Tg installed in the first target installation unit 23 is calculated.

The principle of calculating the absolute distance will be described with reference to FIG. Although it is actually a 3D space, it will be described in 2D for simplicity. The distance value obtained by measuring the target Tg installed in the second target installation unit 24 with the laser interference type length measuring device 2b is u, the angle value of the θ-axis encoder 10 (ψ-axis encoder 12) is θ1 (ψ1), the first If the distance value obtained by measuring the target Tg installed in one target installation unit 23 with the laser interference type length measuring instrument 2b is v and the angle value of the θ-axis encoder 10 (ψ-axis encoder 12) is θ2 (ψ2), From the triangular cosine theorem,
c ² = w ² + (w + (v−u)) ² −2 × w × (w + (v−u)) × cos (θ) Equation 1
Here, θ = θ2-θ1 (ψ = ψ2-ψ1)
There is a relationship. From this equation 1, the absolute distance w can be calculated.

(8) From the absolute distance w calculated in (7) and the angle information θ, ψ measured in (6), the spatial coordinates of the target Tg installed in the first target installation unit 23 are determined.
(9) As shown in FIG. 4, the circumferential position of the measurement auxiliary instrument 20A with respect to the measurement object W is changed, and the operations (6) to (8) are performed three or more times.
(10) The diameter ΦD1 at the position of the target Tg is calculated from the acquired three or more spatial coordinates.
(11) The diameter ΦD2 of the measurement object W is obtained by subtracting the radial offset amount L of the target Tg with respect to the measurement object W from the diameter ΦD1 obtained in (10) (Formula 2).
ΦD2 = ΦD1- (2 × L) Equation 2

  In this diameter measuring method, even if the distance from the laser tracker 1 to the measuring object W is long, it is not necessary to perform tracking control between them, so that the possibility of measurement failure is low and the skill of the operator is not required.

  Since the peripheral surface contact portion 22 has a disk shape and the central axis O is disposed along the vertical direction and passes through the first target installation portion 21, the peripheral surface contact portion 22 has an outer peripheral surface 22a. Any circumferential direction portion may be brought into contact with the outer peripheral surface Wb of the measuring object W. Therefore, it is easy to install the measurement auxiliary instrument 20A on the measurement target W.

  Since the target Tg is installed in the first and second target installation parts 23 and 24 located above the upper end surface contact part 21, even when the measurement auxiliary instrument 20A is located on the opposite side when viewed from the laser tracker 1. The laser beam Lb emitted from the laser tracker 1 strikes the target Tg without being blocked by the measuring object W. Therefore, the laser tracker 1 can measure not only the surface on the near side as seen from the laser tracker 1 but also the spatial coordinates of the opposite surface.

  In the measurement example, the measurement target peripheral surface of the ring-shaped measurement target W is the outer peripheral surface Wb, and the outer peripheral diameter is measured. The inner peripheral diameter is measured using the measurement target peripheral surface as the inner peripheral surface Wc. You can also. In that case, the measurement auxiliary instrument 20A is installed such that the outer peripheral surface 22a of the peripheral surface contact portion 22 is in contact with the inner peripheral surface Wc of the measurement object W. Others are the same as the case of measuring the outer diameter. That is, when measuring the outer peripheral diameter or inner peripheral diameter of the measurement object W that is circular such as a columnar shape or a ring shape, the measurement auxiliary instrument 20A of the present invention is used to specify the measurement object W from the end face of the measurement object W. It is possible to measure the diameter at any position.

  FIG. 5 shows a different embodiment of the measuring aid. This measurement auxiliary instrument 20B also includes an upper end surface contact portion 21 and a peripheral surface contact portion 22 that are the same as those in the above embodiment. The difference from the above embodiment is that there is only one target installation portion 27 above the upper end surface contact portion 21, and this target installation portion 27 is moved between the measurement position P1 and the reference position P2 by guidance of the guide member 28. It is free. The measurement position P1 is a position for measuring the measurement object W, and the reference position P2 is a position for calculating an absolute distance between the point A of the laser tracker 1 and the measurement position P1. The reference position P2 is at a known distance c with respect to the measurement position P1. In this example, the guide member 28 is a linear guide including a guide portion 28a fixed to the upper surface of the upper end surface contact portion 21 and a movable portion 28b movable along the guide portion 28a. A target installation unit 27 is provided.

When the measurement auxiliary instrument 20B having this configuration is used, the following steps (a) to (d) are performed instead of the steps (3) to (6) in the diameter measuring method.
(A) The target installation unit 27 of the measurement auxiliary instrument 20B is positioned at the reference position P2, and the target Tg is installed in the target installation unit 27. As described above, at this time, the operator does not need to track the target Tg from the laser tracker 1 to the measurement target W with the laser beam Lb.
(B) The laser beam Lb is irradiated toward the target Tg, and tracking is started.
(C) The position coordinates (distance value u, angle values θ1, ψ1) of the target Tg when the target installation unit 24 is at the reference position P2 are acquired.
(D) The target installation unit 27 is moved from the reference position P2 to the measurement position P1, and the position coordinates (distance value v, angle value θ2, ψ2) of the target Tg at the measurement position P1 are acquired. The target installation unit 27 is moved while tracking the target Tg with the laser beam Lb. However, since the distance between the reference position P1 and the measurement position P2 is very short, the possibility of failure in tracking is extremely low. In addition, since the target Tg is moved together with the target installation portion 27 by guidance by the guide member 28, the target Tg can be easily moved.

  Then, from the distance values u and v of the position coordinates acquired in (c) and (d) above, and the distance c between the reference position P1 and the measurement position P2, which are known values, the laser tracker 1 is at the measurement position P1. The absolute distance w to the target Tg is calculated. The calculation method is the same as described above. The method for obtaining the spatial coordinates of the measuring object W is the same as described above.

  The measurement auxiliary instrument 20C in FIG. 6 is obtained by adding a moving drive source 30 for moving the target installation unit 27 between the reference position P2 and the measurement position P1 to the measurement auxiliary instrument 20B. The movement drive source 30 is, for example, a motor, and is installed on a support base 31 fixed to the guide portion 28 a of the guide member 28. The rotational motion of the movement drive source 30 is converted into a straight motion by the motion conversion mechanism 32 and transmitted to the target installation unit 27. The motion conversion mechanism 32 is, for example, a ball screw mechanism including a screw shaft 32a and a nut (not shown). When the movement drive source 30 is provided in this way, it is not necessary to manually move the target Tg, so that the measurement work is facilitated.

  FIG. 7 shows a further different embodiment of the measuring aid. The measurement auxiliary instrument 20D has a rod portion 27a extending below the target installation portion 27, and the rod portion 27a is guided in the vertical direction by the guide member 33. And the upper end of the movement range of the target installation part 27 is made into the reference position P2 (the figure (B)), and the lower end is made into the measurement position P1 (the figure (A)). As described above, even when the reference position P2 and the measurement position P1 are arranged above and below, the position coordinates of the target Tg at the measurement position P1 can be obtained in the same manner as described above.

  FIG. 8 shows a different embodiment of the laser tracker. This laser tracker 1A has a tracking light emitting source 50 having a larger beam diameter of the light 51 emitted than the laser light Lb emitted from the laser light source 2a, apart from the laser light source 2a used for length measurement and tracking. Is provided. As the light emission source 50, a semiconductor laser that is relatively inexpensive as compared with a laser such as He—Ne, or LED illumination is used. The light emitting source 50 is provided inside the housing 7, and a mirror 52 is provided for reflecting the emitted light 51 so as to travel on the same optical axis as the laser light Lb from the laser light source 2a.

  The light 51 emitted from the light emission source 50 is reflected by the mirror 52, enters the exact same optical axis as the laser light Lb from the laser light source 2a, and then is reflected by the target Tg and passes through the same path, and the laser tracker 1 Then, the light is reflected by the half mirror 8 and reaches the light receiving unit 3. Since the light beam 51 from the light emitting source 50 has a larger beam diameter than the laser beam Lb from the laser light source 2a, the return light can be detected by the light receiving unit 3 even if the incident position on the target Tg is slightly shifted. .

  The light 51 from the light emitting source 50 is not used for length measurement. That is, the light 51 has the role of finding the target Tg whose position could not be detected by the laser light Lb and starting the tracking operation. After discovering the target Tg, switching to precise tracking with the laser beam Lb is performed. Thus, by providing the tracking-specific light emission source 50 having a large beam diameter, tracking with the laser beam Lb can be easily started even from a distant position.

DESCRIPTION OF SYMBOLS 1,1A, 1B ... Laser tracker 2a ... Laser light source 20A, 20B, 20C, 20D, 40 ... Measurement auxiliary instrument 21 ... Upper end surface contact part 22 ... Peripheral surface contact part 23 ... First target installation part 24 ... Second Target installation unit 27 ... Target installation unit 28 ... Guide member 30 ... Moving drive source 50 ... Light emission source 51 ... Light Lb ... Laser beam O ... Center axis P1 ... Measurement position P2 ... Reference position Tg ... Target W ... Measurement object Wa ... Upper end surface Wb ... Outer peripheral surface (peripheral surface to be measured)

Claims (9)

A measurement auxiliary instrument that is used as an aid to a laser tracker that irradiates a target placed on a measurement object with laser light and finds the spatial coordinates of the target while tracking the position of the target from the reflected light,
An upper end surface contact portion to be brought into contact with the upper end surface of the measurement object;
A peripheral surface contact portion that extends downward from the upper end surface contact portion and makes contact with the peripheral surface of the measurement object;
A first target installation unit provided on an upper portion of the upper end surface contact unit, and the target is installed for measurement of an object to be measured;
The target is installed at a known distance from the first target installation part above the upper end surface contact part, and the target is installed for calculating the absolute distance from the laser tracker to the target installed in the first target installation part. And a second target installation portion. A measurement auxiliary instrument that is used as an aid to a laser tracker that irradiates a target placed on a measurement object with laser light and finds the spatial coordinates of the target while tracking the position of the target from the reflected light,
An upper end surface contact portion to be brought into contact with the upper end surface of the measurement object;
A peripheral surface contact portion that extends downward from the upper end surface contact portion and makes contact with the peripheral surface of the measurement object;
A target installation part which is located above the upper end surface contact part and in which the target is installed;
The target installation unit includes a guide member that freely moves between a measurement position for measuring a measurement object and a reference position for calculating an absolute distance at a known distance from the measurement position. Measuring aids to do.   3. The measurement auxiliary instrument according to claim 2, wherein the guide member guides the target installation portion so as to be movable in the vertical direction, and has an upper end of the moving range as the reference position and a lower end as the measurement position.   The measurement auxiliary instrument according to claim 2 or 3, wherein a movement drive source is provided to move the target installation unit between the reference position and the measurement position.   A laser light source that is used together with the measurement auxiliary instrument according to any one of claims 1 to 4 and that is used to measure a distance to the target and detect an angular position, and a laser light source that is emitted from the laser light source. A laser tracker comprising: a light emitting source that emits light that has the same optical axis as the laser beam and has a light beam diameter larger than that of the laser beam and is used only for detecting an angular position with respect to the target. .   6. The laser tracker according to claim 5, wherein the light emission source uses a semiconductor laser.   7. The laser tracker according to claim 6, wherein the light emission source uses LED illumination. The measurement target circumference of a measurement object having a cylindrical measurement target peripheral surface on the outer periphery or the inner periphery using the measurement auxiliary instrument according to claim 1 and the laser tracker according to claim 5 or 6. A diameter measuring method for measuring the diameter of a surface,
In the state where the laser tracker is installed in the vicinity of the measurement object, the measurement auxiliary instrument is configured such that the upper end surface contact portion is in contact with the upper end surface of the measurement object and the peripheral surface contact portion is the measurement of the measurement object. A process of installing the target peripheral surface in contact with the target peripheral surface;
Installing the target in the second target installation section;
Moving the target to the first target installation section while tracking the target with the laser tracker;
Performing the process of acquiring the spatial coordinates of the target installed in the first target installation unit by the laser tracker,
The process of acquiring the spatial coordinates of the target is repeated three or more times while changing the circumferential position of the measurement auxiliary tool with respect to the measurement object, and the diameter of the measurement target circumferential surface is calculated from the acquired three or more spatial coordinates. The diameter measuring method characterized by the above-mentioned. Using the measurement auxiliary instrument according to any one of claims 2 to 4 and the laser tracker according to claim 5 or 6, a cylindrical measurement target peripheral surface is formed on the outer periphery or the inner periphery. A diameter measurement method for measuring a diameter of the measurement object peripheral surface of a measurement object comprising:
In the state where the laser tracker is installed in the vicinity of the measurement object, the measurement auxiliary instrument is configured such that the upper end surface contact portion is in contact with the upper end surface of the measurement object and the peripheral surface contact portion is the measurement of the measurement object. A process of installing the target peripheral surface in contact with the target peripheral surface;
Installing the target on the target installation unit located at the reference position;
Moving the target installation unit from the reference position to the measurement position while tracking the target with the laser tracker;
Performing the process of acquiring the spatial coordinates of the target installed in the target installation unit located at the measurement position by the laser tracker,
The process of acquiring the spatial coordinates of the target is repeated three or more times while changing the circumferential position of the measurement auxiliary tool with respect to the measurement object, and the diameter of the measurement target circumferential surface is calculated from the acquired three or more spatial coordinates. The diameter measuring method characterized by the above-mentioned.

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