JP6955973B2 - Laser tracking device and gain adjustment method for laser tracking device - Google Patents

Description

The present invention relates to a laser tracking device that emits laser light and a gain adjusting method for the laser tracking device.

Conventionally, a laser tracking device (for example, a laser tracker or the like) that irradiates a target with a laser beam is known (see, for example, Patent Document 1).
The laser device described in Patent Document 1 is a laser tracker that irradiates a retroreflector provided on a moving body with a laser beam and changes the irradiation direction of the laser beam so as to track the moving body.
Specifically, this laser tracker is reflected by a laser interferometer, a biaxial rotation mechanism that directs the optical axis direction of the laser light (emitted light) output from the laser interferometer in an arbitrary direction, and a retroreflector. It is equipped with a detection sensor that detects the deviation of the optical axis of the return light (reflected light). Then, the laser tracker detects the deviation between the emitted light and the incident light by the detection sensor, feedback-controls the biaxial rotation mechanism so that the emitted light and the incident light are coaxial, and emits light at the center of the retroreflector. Is tracked so that it is irradiated.

JP-A-2009-229066

By the way, in a laser tracking device that tracks a target by rotating the emission direction of laser light around the rotation axis by a rotation axis mechanism, the friction coefficient of the bearing of the rotation axis gradually changes due to aging or the like. In such a case, the rotation speed when a predetermined drive signal is input to the motor of the rotation mechanism also changes, so that the drive characteristics when rotating the emission direction of the laser light in the predetermined direction deteriorates, and the tracking of the laser tracking device Performance is reduced. For example, if the friction coefficient of the bearing is low, the laser beam irradiation position will move beyond the retro-reflector, and if the friction coefficient is high, the laser light irradiation position will not be able to keep up with the movement of the retro-reflector, and tracking performance will be achieved. Decreases.
Therefore, in the conventional laser tracker, in order to solve such a problem, the operator samples the speed signal related to the rotation speed of the laser interferometer detected when the two-axis rotation mechanism is step-driven, and the operator , It was necessary to confirm the signal waveform and manually adjust the gain related to the drive control system of the two-axis rotation mechanism.

An object of the present invention is to provide a laser tracking device capable of suppressing a decrease in tracking performance, and a method for adjusting the gain of the laser tracking device.

The laser tracking device of the present invention includes a laser light source that emits laser light, a first angle adjusting means that rotates the laser light source around the first axis based on an input drive command, and an input drive. Based on the command, the second angle adjusting means for rotating the laser light source around the second axis intersecting the first axis, and the second for detecting the amount of rotation of the laser light source centered on the first axis. The one-angle detecting means, the second angle detecting means for detecting the amount of rotation of the laser light source centered on the second axis, and the drive command for rotating the laser light source at a predetermined constant speed to search for a target are described. From the amount of rotation around the first axis and the amount of rotation around the second axis of the laser light source when output to the first angle adjusting means and the second angle adjusting means, the first gain for the first angle adjusting means and The first angle adjusting means is controlled based on the gain setting means for setting the second gain for the second angle adjusting means and the first gain set by the gain setting means, and the gain setting means sets the first angle adjusting means. The second angle adjusting means is controlled based on the second gain, and the laser light source is rotated.

The present invention is a laser tracking device including a first angle adjusting means for rotating a laser light source around a first axis and a second angle adjusting means for rotating a laser light source around a second axis. In a laser tracking device, usually, when tracking a laser beam emitted from a laser light source with respect to a target, a search process of scanning the laser beam to search for the target is performed.
Then, the gain setting means sets the first gain and the second gain based on the amount of rotation of the laser light source when this search process is performed. Then, the control means controls the first rotation mechanism based on the first gain set by the gain setting means, and controls the second rotation mechanism based on the second gain set by the gain setting means.
That is, in the present invention, in the search process, a drive command for driving the laser light source at a constant speed is output to the first angle adjusting means and the second angle adjusting means, and the rotation around each axis detected at that time is output. Adjust the gain based on the amount. For example, in the search process, when the friction coefficient between the shaft member and the bearing in the rotating mechanism that rotates the laser light source around the first axis and the second axis is small, the laser light source makes a desired angle faster than the commanded speed. Rotate over and overshoot. In this case, the gain setting means reduces the first gain and the second gain. Further, when the friction coefficient between the shaft member and the bearing is large, the rotation speed (rotation amount per unit time) becomes small, and the time required to reach a constant speed becomes long. In this case, the gain setting means increases the first gain and the second gain.
As a result, for example, even if the friction coefficient changes between the rotation shaft of the first rotation mechanism or the second rotation mechanism and its bearing due to aging, the first rotation mechanism or the second rotation mechanism or the second rotation mechanism or the second rotation mechanism can be used before the target is tracked and controlled. The gain of the drive control system of the rotation mechanism can be adjusted to an appropriate value. Therefore, it is possible to suppress a decrease in tracking performance when tracking a target with a laser beam.

In the laser tracking device of the present invention, the drive command for searching for the target is
The first scan, in which the laser light source is rotated in the positive direction around the first axis by the first angle adjusting means.
A second scan in which the laser light source is rotated in the positive direction around the second axis by the second angle adjusting means.
The laser light source is rotated in the negative direction around the first axis by a rotation amount larger than the rotation amount in the first scan by the first angle adjusting means, and the laser is rotated by the second angle adjusting means. The fourth scan, in which the light source is rotated in the negative direction around the second axis by a rotation amount larger than the rotation amount in the second scan.
The rotation angle in the first scan performed in the i-th time (i is an integer of 2 or more) is θ _{i, 1} and the rotation angle θ in the third scan performed in the i-1th time. _{The rotation angle φ i, 2} in the second scan performed in the i-th scan (i is an integer of 2 or more), which is larger than _{i-1 and 3} , is the rotation angle in the fourth scan performed in the i-1st scan. It is preferable that the command is made larger than θ _{i-1 and 4.}

In the present invention, by repeating the first scan to the fourth scan as described above in order, the emission direction of the laser beam moves along a substantially rectangular spiral line, and the target is efficiently targeted. You can search.
Further, the second angle adjusting means is not driven during the first scan and the third scan. Therefore, the gain setting means can accurately set the first gain of the drive control system of the first angle adjusting means based on the amount of rotation around the first axis. Similarly, the first angle adjusting means is not driven during the second scan and the fourth scan. Therefore, the gain setting means can accurately set the second gain of the drive control system of the second rotation mechanism based on the rotation speed around the second axis.

In the laser tracking device of the present invention, the gain setting means is
Based on the amount of rotation of the laser light source in the first scan, the first positive direction gain when rotating the laser light source in the positive direction around the first axis is set.
Based on the amount of rotation of the laser light source in the second scan, the second positive direction gain when rotating the laser light source in the positive direction around the second axis is set.
Based on the amount of rotation of the laser light source in the third scan, the first negative direction gain when rotating the laser light source in the negative direction around the first axis is set.
It is preferable to set the second negative direction gain when the laser light source is rotated in the negative direction around the second axis based on the amount of rotation of the laser light source in the fourth scan.

In the first rotation mechanism and the second rotation mechanism, the friction coefficient when the laser light source is rotated in the forward direction and the friction coefficient when the laser light source is rotated in the negative direction (reverse direction) may be different. On the other hand, in the present invention, the first positive direction gain is set based on the amount of rotation when the laser light source is rotated in the positive direction around the first axis in the first scan, and the laser light source is used in the third scan. The first negative direction gain is set based on the amount of rotation when rotating in the negative direction around the first axis. Similarly, the second positive direction gain is set based on the rotation amount during the second scan, and the second negative direction gain is set based on the rotation amount during the fourth scan. As a result, it is possible to set an appropriate gain for each direction in which the laser light sources of the first rotation mechanism and the second rotation mechanism are rotated, and it is possible to more effectively suppress the deterioration of the tracking performance of the laser tracking device.

In the laser tracking device of the present invention, the gain setting means sets the first positive direction gain each time the first scan is performed, and sets the second positive direction gain each time the second scan is performed. It is preferable that the first negative direction gain is set each time the third scan is performed, and the second negative direction gain is set each time the fourth scan is performed.

In the present invention, since the gain is set for each scan, the gain in each direction is gradually set to an appropriate value during the search for the target. Taking the first positive gain as an example, the first positive gain is set by the first scan. Therefore, when the first scan is performed again after the second scan to the fourth scan are performed, the first angle adjusting means is controlled by the first positive gain set after the first scan performed earlier. NS. In this case, in the first scan performed from the second time onward, it is possible to evaluate whether or not the first positive direction gain set based on the first scan performed earlier is an appropriate value. Therefore, in the search process, the gain in each direction can be set to a more appropriate value by repeatedly performing each scan. Further, after the search process, in order to verify whether or not the set gain is appropriate, it is not necessary to move the laser light source again, and the target is immediately tracked by the laser beam after the search process. Tracking processing can be performed.

In the laser tracking device of the present invention, the laser light source detects the amount of deviation of the optical axis between the emitted light which is the laser light emitted from the laser light source and the reflected light which is the laser light reflected by the target. A laser tracking device including an optical axis detection sensor, wherein the control means controls driving of the first angle adjusting means and the second angle adjusting means so that the deviation amount becomes a predetermined value or less. Is preferable.
In the present invention, the laser tracking device feedback-controls so that the emitted light tracks the target based on the amount of deviation between the emitted light and the reflected light. As a result, the laser tracking device can suitably track the target. At this time, as described above, even if there is a change in the friction coefficient in the rotation mechanism of the laser light source, the laser light is suitably tracked to the target by setting the control gain according to the change in the friction coefficient. Can be made to.

The gain adjusting method of the laser tracking device of the present invention includes a laser light source that emits laser light, a first angle adjusting means that rotates the laser light source around the first axis based on an input drive command, and a first angle adjusting means. Based on the input drive command, the second angle adjusting means for rotating the laser light source around the second axis intersecting with the first axis, and the amount of rotation of the laser light source around the first axis. A method for adjusting the gain of a laser tracking device, comprising: a first angle detecting means for detecting a light source, and a second angle detecting means for detecting the amount of rotation of the laser light source about the second axis. A search step of driving the laser light source at a constant speed to search for a target by outputting a drive command to the first angle adjusting means and the second angle adjusting means to search for the target, and the laser in the search step. A gain setting step of setting a first gain for the first angle adjusting means and a second gain for the second angle adjusting means from the amount of rotation around the first axis and the amount of rotation around the second axis of the light source. It is characterized by carrying out.
In the present invention, as in the above invention, the first gain and the second gain are set by the gain setting means when searching for the target by the search process. Therefore, even if the friction coefficient between the shaft member that rotates the laser light source and the bearing changes due to deterioration over time, it is possible to adjust the appropriate gain corresponding to the change in the friction coefficient before the tracking control of the laser beam. , It is possible to suppress the deterioration of the tracking performance of the laser tracking device.

The figure which shows the schematic structure of the laser tracker which concerns on one Embodiment of this invention. The figure which shows the control structure of the laser tracker of this embodiment. The flowchart which shows the gain adjustment method in the laser tracker of this embodiment. The figure which shows the movement path in the emission direction of a laser beam in the search process of this embodiment. The flowchart which shows the evaluation of the speed signal passing response and the gain adjustment processing.

Hereinafter, an embodiment of the present invention will be described.
[Device configuration]
FIG. 1 is a diagram showing a schematic configuration of the laser tracker 10 of the present embodiment. FIG. 2 is a schematic view showing a control configuration of the laser tracker 10 of the present embodiment.
In FIG. 1, the laser tracker 10 of the present embodiment corresponds to the laser tracking device of the present invention, and the laser tracker 10 tracks the dynamic position of a target 31 supported so as to be arbitrarily movable in three-dimensional space. At the same time, the three-dimensional position is measured, and the distance from the laser tracker 10 to the target 31 is measured. The target 31 is supported via a head 30 by a moving mechanism (not shown) that is three-dimensionally movable. Specific examples of such a mechanism include a machine tool in which the spindle moves three-dimensionally with respect to the table, a three-dimensional measuring device, and the like.
The target 31 is a retroreflector and is attached to the head 30. The target 31 may be another retroreflector.

The laser tracker 10 has a base 11, a first support 12, a second support 13, a laser interferometer 14, and a control 15.
The base 11 is placed (or fixed) on a stage 32 of, for example, a machine tool or a three-dimensional measuring device.
The first support portion 12 is rotatably supported by the first rotation mechanism 16 (see FIG. 2) with respect to the base 11 with the first axis L1 (reference axis) as the rotation center. The first axis L1 is, for example, an axis orthogonal to the upper surface of the stage 32.
The second support portion 13 is rotatably supported by the second rotation mechanism 17 (see FIG. 2) with respect to the first support portion 12 with the second axis L2 (reference axis) as the rotation center. The second axis L2 is an axis that intersects (orthogonally in this embodiment) the first axis L1.
The intersection of the first axis L1 and the second axis L2 is the measurement reference point M by the laser tracker 10.

The first rotation mechanism 16 includes a first motor 161 (see FIG. 2) corresponding to the first angle adjusting means of the present invention, and a first bearing mechanism 162.
The first motor 161 is a motor that rotates the first support portion 12 around the first shaft L1.
The first bearing mechanism 162 rotatably supports the first support portion 12 with respect to the base 11. Although not shown, the first bearing mechanism 162 includes, for example, a shaft member rotated by the first motor 161 and a bearing that receives the shaft member. In such a first bearing mechanism 162, the coefficient of friction between the shaft member and the bearing may fluctuate due to aging or the like.
The first rotation mechanism 16 enables the laser interferometer 14 to rotate in the range of, for example, 0 ° to 180 ° with respect to the azimuth angle direction.

Further, the first rotation mechanism 16 is provided with a first encoder 163 (see FIG. 2) which is a first angle detecting means.
The first encoder 163 is composed of, for example, a rotary encoder, and detects the position (azimuth angle θ) of the first support portion 12 from a predetermined origin position (θ = 0 °). Therefore, the rotation angle (rotation amount) of the laser interferometer 14 in the azimuth angle direction can be calculated from the change in the azimuth angle θ detected by the first encoder 163, and the orientation of the laser interferometer 14 can be calculated from the rotation angle per unit time. The moving speed (rotational speed) in the angular direction can be calculated.

Similarly, the second rotation mechanism 17 includes a second motor 171 corresponding to the second angle adjusting means of the present invention and a second bearing mechanism 172.
The second motor 171 is a motor that rotates the second support portion 13 about the second shaft L2.
The second bearing mechanism 172 rotatably supports the second support portion 13 with respect to the first support portion 12. Although not shown, the second bearing mechanism 172 includes, for example, a shaft member rotated by the second motor 171 and a bearing that receives the shaft member. In such a second bearing mechanism 172, similarly to the first bearing mechanism 162, the coefficient of friction between the shaft member and the bearing may fluctuate due to aging or the like.
The second rotation mechanism 17 enables the laser interferometer 14 to rotate in the range of, for example, 0 ° to 90 ° with respect to the elevation angle direction.

Further, the second rotation mechanism 17 is provided with a second encoder 173 (see FIG. 2) which is a second angle detecting means.
The second encoder 173 is composed of, for example, a rotary encoder, and detects the position (elevation angle φ) of the second support portion 13 from a predetermined origin position (φ = 0 °). Therefore, the rotation angle (rotation amount) of the laser interferometer 14 in the elevation angle direction can be calculated from the change in the elevation angle φ detected by the second encoder 173, and the rotation angle per unit time is the elevation angle direction of the laser interferometer 14. The moving speed (rotational speed) can be calculated.

The laser interferometer 14 corresponds to the laser light source of the present invention, is supported by the second support portion 13, and emits laser light (aspect angle θ, elevation angle φ) in the directions (azimuth angle θ, elevation angle φ) specified by the two rotation mechanisms 16 and 17. The emitted light) is irradiated, the laser light (reflected light) retroreflected by the target 31 is received, and the change in the distance between the measurement reference point M and the target 31 is measured from the interference between the irradiation light and the reflected light.
Further, the laser interference meter 14 includes an optical axis detection sensor 141 (see FIG. 2) that detects the main optical axis of the emitted light and the main optical axis of the reflected light. As the optical axis detection sensor 141, for example, a sensor having a conventional configuration described in Japanese Patent Application Laid-Open No. 2007-309677 can be used, and the light spot position detection of each of the emitted light and the reflected light by a semitransmissive mirror can be used. An example thereof is a configuration in which the light spot position detection element detects the amount of deviation between the spot position of the emitted light and the spot position of the reflected light by reflecting the light on the element.

As shown in FIG. 2, the control unit 15 includes a first control unit 151 and a second control unit 152 connected to the optical axis detection sensor 141. The first control unit 151 and the second control unit 152 correspond to the control means of the present invention, and the first control unit 151 and the second control unit 152 correspond to the control means of the present invention so that the amount of deviation of the optical axis between the emitted light and the reflected light detected by the optical axis detection sensor becomes zero. Feedback control is performed on the one motor 161 and the second motor 171.
Further, a first programmable gain amplifier (hereinafter referred to as a first PGA153) is provided between the first control unit 151 and the first motor 161 and between the second control unit 152 and the second motor 171. Is provided with a second programmable gain amplifier (hereinafter referred to as a second PGA154).

Further, the control unit 15 includes a gain setting means 155 for setting the gains of the first PGA 153 and the second PGA 154.
The gain setting means 155 samples the speed signal output from the first encoder 163 and the speed signal output from the second encoder 173 when performing the search process for searching for the target 31 to be tracked by the laser beam. These velocity signals are evaluated as velocity signal transient responses, and the gain is set based on the evaluation results. The details of the gain setting method by the gain setting means 155 will be described later.

[Gain adjustment method in laser tracker 10]
Next, the gain adjusting method in the laser tracker 10 described above will be described.
FIG. 3 is a flowchart showing a gain adjusting method in the present embodiment.
In the laser tracker 10 of the present embodiment, for example, when a measurement command for measuring the distance to the target 31 is input by the operation of the operator, and during the length measurement by the laser interferometer 14, the emitted light deviates from the target 31. In the case (when the amount of deviation detected by the optical axis detection sensor 141 exceeds the measurable range (threshold) and the optical axis of the reflected light cannot be detected), the control unit 15 determines the drive mode of the laser tracker 10. Is switched to the search mode (step S1), and the search process (search step) is performed.

In the search process, the control unit 15 initializes the variable i indicating the number of scans and the variable j indicating the scanning direction to set i = 1 and j = 1 (step S2).
Next, the control unit 15 executes a search process for the variables i and j (step S3).

The search process in step S3 will be described in detail.
FIG. 4 is a diagram showing a movement path in the emission direction of the laser beam in the search process of the present embodiment. In FIG. 4, in a plane orthogonal to the optical axis of the laser light when the laser beam to the start position P ₀ is irradiated, shows a movement path of the laser beam.
The control unit 15 performs the j-th scan according to the variable j.
That is, when j = 1, the control unit 15 performs the first scan for moving the emission direction of the laser light to the −X side of FIG. 4, and when j = 2, the emission direction of the laser light is changed to the −X side of FIG. The second scan for moving to the −Y side is performed, and the third scan for moving the emission direction of the laser light to the + X side in FIG. 4 is performed when j = 3, and the laser light is emitted when j = 4. A fourth scan is performed in which the direction is moved to the + Y side of FIG.

More specifically, in the first scan of j = 1, the control unit 15 directs the laser interferometer 14 from the first control unit 151 to the first motor 161 at a constant speed in the forward direction (for example, in the present embodiment). , A drive command for rotating the base 11 by a predetermined time in a counterclockwise direction about the first axis L1 when the base 11 is viewed from the first support portion 12 along the first axis L1 is output. That is, the first rotation mechanism 16 rotates the azimuth angle θ of the laser interference meter 14 in the positive direction by a _{predetermined rotation amount (angle θ i, 1).}
As a result, the emission direction of the laser beam moves to the −X side shown in FIG. 4, for example, by x _{i, 1.}
In the present embodiment, the first scan to the fourth scan are repeatedly performed in order, but the angles θ _{i and 1 in} which the laser interference meter 14 is driven in the second and subsequent i-th first scans are i−. The angle is larger than the _{angle θ i-1,} 3 in which the laser interferometer 14 is driven in the first third scan. Therefore, as shown in FIG. 4, x _{i, 1} > x _i-1 , 1.

In the second scan performed when j = 2, the control unit 15 directs the laser interferometer 14 from the second control unit 152 to the second motor 171 at a constant speed in the forward direction (for example, in the present embodiment, in the present embodiment. A drive command is output to the effect that the rotation is performed for a predetermined time in the direction toward the stage 32 (the direction toward the stage 32 is the positive direction). That is, the second rotation mechanism 17 rotates the elevation angle φ of the laser interference meter 14 by a predetermined angle φ _{i, 2} . Since the first gain and the second gain are calculated individually, the speed in the second scan may be different from the speed in the first scan.
As a result, the emission direction of the laser beam moves from the destination in the first scan to the −Y side shown in FIG. 4, for example, y _{i, 2} .
In the present embodiment, the first scan to the fourth scan are repeatedly performed in order, but the angles φ _{i and 2 in} which the laser interference meter 14 is driven in the second and subsequent i-second scans are i−. The angle at which the laser interferometer 14 is driven in the first fourth scan is larger than the _{angle φ i-1,4.} Therefore, as shown in FIG. 4, y _{i, 2} > y _i-1,2 .

In the third scan performed when j = 3, the control unit 15 directs the laser interferometer 14 from the first control unit 151 to the first rotation mechanism 16 at a constant speed in the negative direction (opposite to the first scan). Outputs a drive command to rotate for a predetermined time in the direction of). At this time, in the present embodiment, the laser interferometer 14 is rotated at the same speed as the first scan for a longer time than that of the first scan. That is, in the third scan, the first rotation mechanism 16 rotates the azimuth angle θ of the laser interference meter 14 by a rotation amount (angle θ _{i, 3} ) _{larger than the angle θ i, 1 in the first scan.}
As a result, the emission direction of the laser beam moves to the + X side shown in FIG. 4, for example, by x _{i, 3} (> x _{i, 1} ).

In the fourth scan performed when j = 4, the control unit 15 sends the laser interferometer 14 from the second control unit 152 to the second rotation mechanism 17 at a constant speed in the negative direction (opposite to the second scan). Outputs a drive command to rotate for a predetermined time in the direction of). At this time, in the present embodiment, the laser interferometer 14 is rotated at the same speed as the second scan for a longer time than that of the second scan. That is, in the fourth scan, the second rotation mechanism 17 rotates the elevation angle φ of the laser interferometer 14 by a rotation amount (angle φ _{i, 4} ) _{larger than the angle φ i, 2 in the second scan.}
As a result, the emission direction of the laser beam moves to the + Y side shown in FIG. 4, for example, by y _{i, 4} (> y _{i, 2} ).
In the present embodiment, by repeatedly performing the first scan to the fourth scan, the emission direction of the laser beam is moved along the rectangular spiral line as shown in FIG.

Further, during the scanning process in step S3, the velocity signal (velocity signal transient response) in the rotational movement of the laser interferometer 14 is sampled (step S4). Sampling of the velocity signal transient response is obtained, for example, by counting the number of pulses (angle change amount) per unit time of the detection signals output from the first encoder 163 and the second encoder 173. The velocity signal transient response of the angular velocity in the azimuth direction can be detected based on the detection signal from the first encoder 163, and the velocity signal transient response of the angular velocity in the elevation angle direction can be detected based on the detection signal from the second encoder 173. Further, the sampled velocity signal transient response is stored in a storage circuit such as a memory (not shown) provided in the control unit 15.
In this embodiment, since each scan from the first scan to the fourth scan is performed in order, when each scan is switched, it corresponds to a corner portion in the rectangular spiral shape in FIG. 4, and the laser interference meter 14 is rotationally driven. This is the part where acceleration / deceleration is performed. In the present embodiment, the velocity signal transient response at the timing of accelerating / decelerating the laser interferometer 14 can be obtained by sampling the velocity signal transient response during each scanning process.

Further, the control unit 15 determines whether or not the target 31 has been searched during the scanning process in step S3 (step S5).
Specifically, the control unit 15 determines whether or not the target 31 has been searched based on the signal corresponding to the amount of deviation of the optical axis between the emitted light and the reflected light output from the optical axis detection sensor 141. .. That is, when there is no reflected light from the target 31, the optical axis detection sensor 141 detects only the optical axis of the emitted light, so that the amount of deviation is not detected. On the other hand, when there is reflected light, the optical axis detection sensor 141 detects the amount of deviation of the optical axis between the emitted light and the reflected light. Therefore, in step S5, the control unit 15 monitors the amount of deviation detected by the optical axis detection sensor 141, and when a signal corresponding to the amount of deviation is output, determines Yes in step S5.

If it is determined to be Yes in step S5, the control unit 15 stops the movement of the laser interferometer 14 (step S6). In this case, the velocity signal transient response sampling from the start of the j-scan to the search for the target 31 is performed.
Further, if No is determined in step S5, the control unit 15 further determines whether or not the j-scanning has been completed (step S7), and if No is determined in step S7, the j-th Scanning is continued and sampling of the velocity signal transient response is continued (returning to step S3).

After step S6 and when it is determined Yes in step S7, the gain setting means 155 reads the velocity signal transient response stored in the memory, evaluates it, and sets the gain in the direction corresponding to the variable j. (Step S8; gain setting step). FIG. 5 is a flowchart showing the gain setting step of step S8.
In step S8, the gain setting means 155 first determines whether or not the velocity signal transient response in the i-scan is overshooting (step S81).
For example, when j = 1, when switching from the first scan to the second scan, the drive of the laser interferometer 14 in the azimuth angle direction is decelerated. At this time, when the friction coefficient of the first bearing mechanism 162 of the first rotation mechanism 16 is small, the rotation angle of the laser interferometer 14 exceeds _{the rotation angle θ i, 1 commanded by the drive command.} The rotation speed that moves and is detected is also faster than the speed specified by the drive command.

If Yes is determined in step S81, the gain setting means 155 reduces the gain when driving the laser interferometer 14 in the direction corresponding to the variable j (step S82).
Here, when j = 1, the gain setting means 155 gains the first PGA 153 when the first motor 161 is rotationally driven in the positive direction based on the determination of the velocity signal transient response detected during the first scan. Decrease (first positive gain).
When j = 2, the gain setting means 155 gains (second) the second PGA 154 when the second motor 171 is rotationally driven in the positive direction based on the determination of the velocity signal transient response detected during the second scan. Positive gain) is reduced.
When j = 3, the gain setting means 155 of the first PGA 153 when the first motor 161 is rotationally driven in the negative direction (reverse direction) based on the determination of the velocity signal transient response detected during the third scan. Decrease the gain (first negative direction gain).
When j = 4, the gain setting means 155 gains (second) the second PGA 154 when the second motor 171 is rotationally driven in the negative direction based on the determination of the velocity signal transient response detected during the fourth scan. Negative gain) is reduced.

On the other hand, if No is determined in step S81, the gain setting means 155 determines whether or not the time constant of the velocity signal transient response in the i-scan is equal to or greater than a predetermined value (step S83).
For example, when j = 1, the driving of the laser interferometer 14 in the azimuth angle direction (positive direction) is accelerated at the start of the first scan. At this time, when the friction coefficient of the first bearing mechanism 162 of the first rotation mechanism 16 is high, it takes a longer time than the standard for the rotation amount of the laser interferometer 14 to reach the speed commanded by the drive command. Is required, and the time constant is equal to or greater than the predetermined value.

If it is determined to be Yes in step S83, the gain setting means 155 increases the gain when driving the laser interferometer 14 in the direction corresponding to the variable j (step S84).
Here, as in step S82, the gain setting means 155 reduces the gain corresponding to the variable j.
That is, when j = 1, the gain setting means 155 increases the first positive gain based on the determination of the velocity signal transient response detected during the first scan.
When j = 2, the gain setting means 155 increases the second positive gain.
When j = 3, the gain setting means 155 increases the first negative gain.
When j = 4, the gain setting means 155 increases the second negative gain.

If No is determined in step S83, it is assumed that the gain set in the current first PGA153 and second PGA154 is the optimum value, and the gain is not changed (step S85).

After the above step S8, the control unit 15 determines whether or not to end the search process (step S9). For example, if the target 31 is searched for in step S5 during the search process in step S2, it is determined as Yes in step S9, and the gain adjustment process is terminated.
If it is determined to be Yes in step S9, the control unit 15 switches the drive mode from the search mode to the tracking mode, and drives the first rotation mechanism 16 and the second rotation mechanism 17 based on the set gain. Controlled, the laser beam emitted from the laser interferometer 14 is continuously shifted to the tracking operation of tracking the target 31.

If it is determined to be No in step S9, the control unit 15 determines whether or not the variable j is j = 4 (step S10), and if it is determined to be No in step S10, the variable j is set to 1. Addition (step S11), and the process returns to step S3. Further, if it is determined to be Yes in step S10, _{it is determined whether or not the variable i is the preset maximum value I max} (step S12), and if it is determined to be No in step S12, the variable j is determined. Is initialized (set to j = 1), 1 is added to the variable i (step S13), and the process returns to step S3.
That is, as shown in FIG. 4, the process of moving the emission direction of the laser light in a rectangular spiral shape and adjusting the gain at the timing when the emission direction of the laser light is moved to the corner of the rectangle is a variable. Repeat until i reaches I _max. In other words, the scanning process and the gain setting process are alternately performed, so that the gain in each direction is set to the optimum value.

Also, if it is determined as Yes at step S12, as it was to explore the target 31 within a predetermined range around the start position P _0, and executes error processing (step S14), and ends the search process.

[Action and effect of this embodiment]
In the laser tracker 10 of the present embodiment, a velocity signal transient based on a detection signal detected by the first encoder 163 when the laser interferometer 14 is moved at a constant speed according to a predetermined movement path by a search process for searching for a target 31. The response sets the first gain of the first PGA153, and the velocity signal transient response based on the detection signal detected by the second encoder 173 sets the second gain of the second PGA154. That is, the gain setting means 155 reduces the gain when the velocity signal transient response is overshooting, and increases the gain when the time constant of the velocity signal transient response is long. As a result, even if the friction coefficient fluctuates due to aging or the like in the first bearing mechanism 162 of the first rotation mechanism 16 and the second bearing mechanism 172 of the second rotation mechanism 17, it is optimal to cancel the influence. The control gain can be set.
Further, in the laser tracker 10 for tracking the laser beam to the target 31, it is necessary to specify the position of the target 31 to be tracked, so that the search process before the tracking process is indispensable. In the present embodiment, the first gain and the second gain are set based on the velocity signal transient response detected in the search process performed immediately before the tracking process. Therefore, for example, when the power is turned on or set in advance. Compared with the case where the gain is adjusted at the time, the more optimum first gain and second gain can be set, and the deterioration of the tracking performance can be suppressed more reliably.

In the present embodiment, in the search process, the laser interferometer 14 is rotated by the first rotation mechanism 16 in the positive direction of the azimuth angle direction (around the first axis), and the laser interferometer 14 is rotated by the second rotation mechanism 17. The second scan, which rotates in the positive direction in the elevation angle direction (around the second axis), and the first rotation mechanism 16 rotate the laser interferometer 14 in the negative direction in the azimuth angle direction (around the first axis), which is larger than that in the first scan. The third scan, which rotates by the amount (rotation angle), and the second rotation mechanism 17, cause the laser interferometer 14 to rotate in the negative direction in the elevation angle direction (around the second axis) with a larger rotation amount (rotation angle) than in the second scan. The rotating fourth scan is repeated in sequence. _{Then, the rotation angles θ i, 1} in the first scan performed after the i (i ≧ 2) th scan are made larger than _{the rotation angles θ i-1} , 3 in the third scan performed in the i-1st scan. , I (i ≧ 2) The rotation angle φ _{i, 2} in the second scan performed after the first scan is made larger than _{the rotation angle φ i-1} , 4 in the fourth scan performed in the i-1st scan.
By performing the search process by such a drive command, the emission direction of the laser beam can be moved to a rectangular spiral line centered on the _{start position P 0} , and the laser beam can be moved in order from the position closest to the _{start position P 0.} The target 31 can be searched efficiently.
Further, when the search process is performed along such a line, the second rotation mechanism 17 is not driven and only the first rotation mechanism 16 is moved during the first scan and the third scan. The first encoder 163 does not include noise caused by vibration or the like driven by the second rotation mechanism 17, and the first gain can be set with high accuracy. Similarly, since the first rotation mechanism 16 is not driven during the second scan and the fourth scan, the second gain can be set with high accuracy.

Then, in the present embodiment, the first positive direction gain when the laser interferometer 14 is rotated in the positive direction by the first rotation mechanism 16 is obtained from the velocity signal transient response from the first encoder 163 detected in the first scan. From the velocity signal transient response from the first encoder 163 detected in the third scan, the first negative direction gain when the laser interferometer 14 is rotated in the negative direction by the first rotation mechanism 16 is set.
That is, in the present embodiment, the rotation directions of the laser interference meter 14 are opposite in the first scan and the third scan, and the gain can be set according to each direction. Thereby, for example, the driving performance of the first rotation mechanism 16 can be maintained higher than the case where the same first gain is used in the positive direction and the negative direction.
Similarly, from the velocity signal transient response detected in the second scan, the second positive direction gain when the laser interferometer 14 is rotated in the positive direction by the second rotation mechanism 17 is set, and the laser interferometer 14 is detected in the fourth scan. From the velocity signal transient response, the second negative direction gain when the laser interferometer 14 is rotated in the negative direction by the second rotation mechanism 17 is set. As a result, the driving performance of the second rotation mechanism 17 can be maintained at a higher level.

Further, in the present embodiment, each time the j-scan is completed, the gain with respect to the moving direction of the laser interferometer 14 corresponding to the j-scan is set. For example, when the first scan is completed, the first positive gain is set and the second scan is performed. In this way, the gain for the next (i + 1) is set every time the j-th scan is completed, that is, every time the emission direction of the laser beam reaches the corner of the rectangular spiral movement path. In the jth scan (the second time), it is possible to evaluate whether or not the previously set gain is appropriate, and by performing the jth scan a plurality of times in the search process, the first motor 161 and the second The optimum gain related to the drive control of the motor 171 can be set.

[Modification example]
The present invention is not limited to the above-described embodiment, and modifications and the like within a range in which the object of the present invention can be achieved are included in the present invention.
For example, in the above embodiment, as the laser apparatus of the present invention, an apparatus for tracking the laser beam with respect to the target 31 and measuring the distance between the target 31 and the measurement reference point M has been exemplified, but the present invention is not limited thereto.
For example, a laser tracking device that does not have a length measuring function and only tracks the target 31 may be used. That is, instead of the laser interferometer 14 of the above embodiment, a laser light source having a light source unit that emits laser light and an optical axis detection sensor that detects the amount of deviation between the emitted light and the reflected light may be used.

Further, in the above embodiment, the speed (angular velocity) for rotating the laser interferometer 14 is the same in the first scan and the third scan, and the speed (angular velocity) for rotating the laser interferometer 14 in the second scan and the fourth scan. ) Are the same, but the drive commands may be used to command different speeds in the first scan to the fourth scan. That is, if the drive command does not change the speed during each of the first scan, the second scan, the third scan, and the fourth scan and moves at a predetermined constant speed, the laser interference is performed at any speed. A total of 14 may be driven.
If the speed is different in each scan, the rotation angle (angle θ _{i, 1} , φ _{i, 2} , θ _{i, 3} , φ _{i, 4} ) in each scan is set to a predetermined value, that is, , The time in each scan is adjusted so that the emission direction of the laser beam moves along the rectangular spiral line.

In the search process of the above embodiment, the j-scanning and the gain setting based on the j-scanning are alternately performed, and the control gain when driving the first rotation mechanism 16 and the second rotation mechanism 17 is once. Controlled to set to the optimum value during the search process. In contrast, the speed signal transient response from the start position P ₀ to the target 31 is searched (or, if the target 31 can not be searched, i = speed signal transient response until I _Max) gain from May be set. In this case, the corresponding gain is set from the representative value of the velocity signal transient response obtained in the plurality of j-scans. For example, in the setting of the first positive direction gain, the representative value of the velocity signal transient response obtained in the first scan a plurality of times is used. As the representative value, for example, an average value, a maximum value, a minimum value (maximum value at the time of determination in step S81, minimum value at the time of determination in step S83), a mode value, and the like can be used.

In the above embodiment, each time the j-scan is completed, the gain with respect to the moving direction of the laser interferometer 14 corresponding to the j-scan is set, and then the j + 1 scan (in the case of j = 4, the first scan). Was carried out. On the other hand, after the j-scanning is completed, the j + 1th scanning may be performed at the same time as the gain for the moving direction of the laser interferometer 14 corresponding to the j-scanning is set. That is, the gain calculated based on the i-th j-scan may be calculated by the i + 1-th j-scan.

Further, in the above embodiment, a configuration in which the laser interference meter 14 is rotated at an azimuth angle θ and an elevation angle φ by a biaxial rotation mechanism has been illustrated, but the present invention is not limited to this. For example, when the target 31 is displaced only in the azimuth direction, the second rotation mechanism 17 for rotationally moving the laser interferometer 14 in the elevation angle direction may not be provided. In this case, in the search operation of moving the laser interference meter 14 in the azimuth direction to search for the target 31, the laser interference meter 14 may be rotated at a constant speed, and the gain may be set by the velocity signal transient response at that time. ..
Further, the same applies to a laser tracking device having a rotation mechanism of three or more axes. In this case, the laser interference meter 14 is driven to search for the target 31 while keeping the rotation speed around each axis constant. As a result, the control gain around each axis can be set individually.

In the above embodiment, the first positive direction gain is set after the first scan of the first time (i = 1), and the first positive direction gain is temporarily set at the time of the third scan of the first time (i = 1). The first rotation mechanism 16 may be driven by setting the gain in the first negative direction of the above. That is, both the first scan and the third scan are control gains when controlling the first rotation mechanism 16, and even when the friction coefficient in the first bearing mechanism 162 is different in the positive direction and the negative direction. The difference is small. Therefore, as described above, by setting the first positive direction gain as the temporary first negative direction gain during the third scan, the laser interferometer 14 can be smoothly rotated during the third scan, and the target 31 can be rotated smoothly. Search efficiency can be improved.
Similarly, the second positive direction gain is set after the second scan, and the second positive direction gain is set as a temporary second negative direction gain during the fourth scan to drive the second rotation mechanism 17. You may let me.

Further, in the above embodiment, both the first positive direction gain and the first negative direction gain are calculated, and both the second positive direction gain and the second negative direction gain are calculated. When controlling 161, the first gain may be used regardless of the forward and reverse directions, and when controlling the second motor 171, the second gain may be used regardless of the forward and reverse directions.
In this case, the first gain is set by the first scan, and the laser interferometer 14 is rotated based on the first gain in the third scan to evaluate whether or not the first gain is an appropriate gain. can. Similarly, the second gain can be set by the second scan, and the laser interferometer 14 can be rotated based on the second gain in the fourth scan to evaluate whether or not the second gain is an appropriate gain. can.

In the above embodiment, as a drive command when searching for the target 31, only the first rotation mechanism 16 is driven in the first scan and the third scan, and only the second rotation mechanism 17 is driven in the second scan and the fourth scan. However, it is not limited to this.
For example, as shown below, it may be a drive command for driving both the first rotation mechanism 16 and the second rotation mechanism 17 in each scan.
In the first scan, the first motor 161 is rotated in the positive direction at a constant speed, and the second motor 171 is rotated in the positive direction at a constant speed.
In the second scan, the rotation direction of the first motor 161 is reversed and rotated in the negative direction at a constant speed, and the rotation direction of the second motor 171 is maintained and rotated in the positive direction at a constant speed.
In the third scan, the rotation direction of the first motor 161 is maintained and rotated in the negative direction at a constant speed, and the rotation direction of the second motor 171 is reversed to rotate in the negative direction at a constant speed. At this time, the amount of rotation (rotation angle) of the first motor 161 and the second motor 171 is increased as compared with the time of the first scanning.
In the fourth scan, the rotation direction of the first motor 161 is reversed and rotated at a constant speed in the positive direction, and the rotation direction of the second motor 171 is maintained and rotated at a constant speed in the negative direction. At this time, the amount of rotation (rotation angle) of the first motor 161 and the second motor 171 is increased as compared with the second scanning.
Then, in the first scan after the i (i ≧ 2) times, the amount of rotation (rotation angle) in the first motor 161 and the second motor 171 is increased as compared with the third scan of the i-1st time, i. In the second scan (i ≧ 2) and thereafter, the amount of rotation (rotation angle) in the first motor 161 and the second motor 171 is increased as compared with the fourth scan in the i-1st time.
Even with such a drive command, the emission direction of the laser beam is moved along the rectangular spiral line, and the target 31 can be suitably searched.

At this time, as in the above embodiment, by evaluating the velocity signal transient response and setting the gain after each scan, both the first positive direction gain and the second positive direction gain are set immediately after the first scan. can do.
Further, immediately after the second scanning, it is possible to evaluate whether or not the set second positive direction gain is appropriate, and if it is insufficient, it is possible to make fine adjustments. In addition, the first negative gain can be set immediately after the second scan. In the second scan of the first (i = 1), the second scan is performed with the first positive gain set in the first scan as a temporary first negative gain, as in the modification described above. May be good.
Similarly, immediately after the third scan, the set first negative direction gain can be evaluated and the second negative direction gain can be set. In the first (i = 1) third scan, the third scan may be performed with the second positive gain set in the second scan as a temporary second negative gain.
Immediately after the fourth scan, the first positive gain set immediately after the first scan and the second negative gain set during the third scan can be evaluated.
Therefore, the first positive direction gain, the second positive direction gain, the first negative direction gain, and the second negative direction gain can be set one scan earlier than the above embodiment.

In the above embodiment, the positive direction around the first axis L1 is set as the counterclockwise direction, but it may be the clockwise direction. In this case, the emission direction of the laser light is the emission direction of the laser light in the first scanning. Moves to the + X side. Similarly, the positive direction around the second axis L2 is the direction toward the stage 32, but it may be the direction away from the stage 32. In this case, the emission direction of the laser beam moves to the + Y side in the second scan.
Further, in this application example, the first rotation mechanism 16 is controlled in the first scan and the third scan, and the second rotation mechanism 17 is controlled in the second scan and the fourth scan, but in the first scan and the third scan. The drive of the second rotation mechanism 17 may be controlled to control the drive of the first rotation mechanism 16 in the second scan and the fourth scan. In this case, the emission direction of the laser beam is first moved in the elevation direction in the first scan, moved in the azimuth direction in the second scan, and moved in the opposite side to the first scan in the elevation direction in the third scan. In the fourth scan, it is moved to the side opposite to the second scan in the azimuth direction. Therefore, as in the above embodiment, the emission direction of the laser beam is moved in a rectangular spiral shape.

The present invention can be used for a laser tracking device, a laser tracker, or the like that rotates a laser light source or a laser interferometer that emits laser light around a rotation axis to track a target.

10 ... Laser tracker (laser tracking device), 11 ... Base, 12 ... First support, 13 ... Second support, 14 ... Laser interferometer (laser light source), 15 ... Control, 16 ... First rotation mechanism, 17 ... Second rotation mechanism, 31 ... Target, 141 ... Optical axis detection sensor, 151 ... First control unit (control means), 152 ... Second control unit (control means), 153 ... First PGA, 154 ... Second PGA, 155 ... Gain setting means, 161 ... First motor (first angle adjusting means), 162 ... First bearing mechanism, 163 ... First encoder (first angle detecting means), 171 ... Second motor (second angle) Adjusting means), 172 ... second bearing mechanism, 173 ... second encoder (second angle detecting means), L1 ... first axis, L2 ... second axis.

Claims (6)

A laser light source that emits laser light and
Based on the input drive command, the first angle adjusting means for rotating the laser light source around the first axis, and
A second angle adjusting means for rotating the laser light source around a second axis intersecting the first axis based on an input drive command.
A first angle detecting means for detecting the amount of rotation of the laser light source about the first axis, and
A second angle detecting means for detecting the amount of rotation of the laser light source about the second axis, and
The amount of rotation around the first axis of the laser light source when a drive command for rotating the laser light source to search for a target is output to the first angle adjusting means and the second angle adjusting means at a predetermined constant speed. A gain setting means for setting a first gain for the first angle adjusting means and a second gain for the second angle adjusting means from the amount of rotation around the second axis, respectively.
The first angle adjusting means is controlled based on the first gain set by the gain setting means, and the second angle adjusting means is controlled based on the second gain set by the gain setting means. , A laser tracking device including a control means for rotating the laser light source. In the laser tracking device according to claim 1,
The drive command for searching for the target is
The first scan, in which the laser light source is rotated in the positive direction around the first axis by the first angle adjusting means.
A second scan in which the laser light source is rotated in the positive direction around the second axis by the second angle adjusting means.
The laser light source is rotated in the negative direction around the first axis by a rotation amount larger than the rotation amount in the first scan by the first angle adjusting means, and the laser is rotated by the second angle adjusting means. The fourth scan, in which the light source is rotated in the negative direction around the second axis by a rotation amount larger than the rotation amount in the second scan.
_{The rotation angle θ i, 1} in the first scan performed in the i-th time (i is an integer of 2 or more) is repeated in the order of _{i-1 and the rotation angle θ i} in the third scan performed in the i-1st time. _{The rotation angle φ i, 2} in the second scan performed in the i-th scan (i is an integer of 2 or more), which is larger than _-1,3 , is changed to the rotation angle θ in the fourth scan performed in the i-1st scan. A laser tracking device characterized in that it is a command to be larger than _i-1,4. In the laser tracking device according to claim 2.
The gain setting means is
Based on the amount of rotation of the laser light source in the first scan, the first positive direction gain when rotating the laser light source in the positive direction around the first axis is set.
Based on the amount of rotation of the laser light source in the second scan, the second positive direction gain when rotating the laser light source in the positive direction around the second axis is set.
Based on the amount of rotation of the laser light source in the third scan, the first negative direction gain when rotating the laser light source in the negative direction around the first axis is set.
A laser tracking device characterized in that a second negative direction gain when rotating the laser light source in the negative direction around the second axis is set based on the amount of rotation of the laser light source in the fourth scan. In the laser tracking device according to claim 3,
The gain setting means sets the first positive direction gain each time the first scan is performed, sets the second positive direction gain each time the second scan is performed, and performs the third scan. A laser tracking device characterized in that the first negative direction gain is set each time the scanning is performed, and the second negative direction gain is set each time the fourth scanning is performed. In the laser tracking device according to any one of claims 1 to 4.
The laser light source includes an optical axis detection sensor that detects the amount of deviation of the optical axis between the emitted light, which is the laser light emitted from the laser light source, and the reflected light, which is the laser light reflected by the target.
The control means is a laser tracking device that controls the driving of the first angle adjusting means and the second angle adjusting means so that the deviation amount becomes a predetermined value or less. A laser light source that emits laser light, a first angle adjusting means that rotates the laser light source around the first axis based on an input drive command, and the laser light source based on an input drive command. A second angle adjusting means for rotating the second axis intersecting the first axis, a first angle detecting means for detecting the amount of rotation of the laser light source around the first axis, and the first A method for adjusting the gain of a laser tracking device including a second angle detecting means for detecting the amount of rotation of the laser light source about two axes.
A search step of outputting a drive command for driving the laser light source at a predetermined constant speed to search for a target to the first angle adjusting means and the second angle adjusting means to search for the target.
The first gain for the first angle adjusting means and the second gain for the second angle adjusting means are set from the rotation amount around the first axis and the rotation amount around the second axis of the laser light source in the search step, respectively. Gain setting process and
A method of adjusting the gain of a laser tracking device, which comprises carrying out the above.

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