JP5710279B2 - Optical distance measuring device - Google Patents

Description

  The present invention relates to an optical distance measuring device that scans a light beam in a target area and measures the distance of an object existing in the target area.

  2. Description of the Related Art Conventionally, there has been known an optical distance measuring device that measures a distance to a target existing in a target region by, for example, Lissajous scanning of a light beam in the target region. This type of optical distance measuring device includes, for example, an optical scanning unit (two-dimensionally) that includes a light source unit that projects a light beam and a movable unit that two-dimensionally scans the light beam emitted from the light source unit within a target region. A galvanometer mirror), a driving unit that drives the optical scanning unit, a light receiving unit that receives a light beam reflected by an object in the target region, and a time difference between the light beam projection timing and the reflected light reception timing. And a distance measuring unit that measures the distance to the object on the basis thereof. The drive unit supplies, for example, two drive signals having frequencies near the respective resonance frequencies around two orthogonal axes (x-axis and y-axis) of the optical scanning unit to the optical scanning unit. The movable part is driven to swing around the x-axis and the y-axis with a predetermined swing amplitude (maximum value) and swing cycle (see Patent Document 1).

  By the way, in this type of optical distance measuring device, when the light beam projected from the light source unit at a predetermined projection timing is two-dimensionally scanned by the movable unit, the light beam is projected to an intended position in the target area. In order to achieve this, it must be calibrated so that the swing angle of each movable portion around each axis at each light projection timing becomes an intended angle. If each swing angle of the actual movable part has deviated from the intended angle, the optical distance measuring device will detect the deviation even though the actual light beam projection position has deviated from the intended position. The distance is calculated based on the reflected light from the determined position, and the calculated distance is measured as if it were a distance to the intended position in the target area. Here, the value of each swing angle at each projection timing is greatly influenced by the swing amplitude (maximum value) around each axis of the movable part determined according to the current value of each drive signal supplied. Each swing amplitude (maximum value) is an important parameter that affects the distance measuring accuracy of the optical distance measuring device.

  However, each actual swing amplitude (hereinafter referred to as “actual swing amplitude”) determined according to the current value of the drive signal may vary due to manufacturing variations of the two-dimensional galvanometer mirror, changes with time, and the like. is there. Therefore, in general, in this type of optical distance measuring device, for example, each actual oscillation amplitude is measured at the time of shipment or maintenance after shipment, and this actual oscillation amplitude is outside the design allowable range. In this case, adjust the current value of the drive signal so that the actual swing amplitude falls within the allowable design range, or conversely, reset the design value to the optical distance measuring device according to the actual swing amplitude actually measured. And proofreading. As a method for obtaining the actual oscillation amplitude, for example, a scanning trajectory of laser light is projected on a flat plate, and the projected scanning trajectory outer edge width is visually measured, and the measured scanning trajectory outer edge width and the two-dimensional galvanometer are measured. A method for obtaining the actual oscillation amplitude based on the distance from the mirror to the flat plate is known. However, in two-dimensional optical scanning, the outer edge of the scanning locus when the laser beam is projected onto a flat plate, for example, is distorted in a pincushion shape, and the scanning locus itself is also distorted. In general, there is a problem that the actual oscillation amplitude cannot be measured with high accuracy in the measurement based on the above.

  In order to solve this problem, in this type of optical distance measuring device, a method of measuring the actual oscillation amplitude using a template is known. This template is predetermined based on, for example, the direction (scanning direction) of the light beam from the optical scanning unit into the target region and a predetermined positional relationship (distance, inclination) between the flat plate and the optical distance measuring device main body. The outer edge or the like of the scanning trajectory obtained for each swing amplitude is made of paper or the like on which the swing amplitude used for obtaining each scanning trajectory is associated. Then, this template is affixed to a flat plate, and the flat plate and the optical distance measuring device main body are placed so as to have the positional relationship (distance, inclination) used when creating the template, and the actual scanning trajectory is projected onto the template and projected. Visually confirming which scanning locus preliminarily drawn on the template the outer edge of the scanned trajectory is coincident, and using the oscillation amplitude corresponding to the scanning locus on the approximately coincident template as the actual oscillation amplitude, The actual oscillation amplitude is measured.

JP 2004-157796 A

  However, when the actual oscillation amplitude is measured using the template as described above before the shipment of this type of optical distance measuring device, the operator scans the flat plate and the optical distance measuring device main body on the template, for example. It was difficult to arrange them so as to coincide with the positional relationship (distance, inclination) used when obtaining the trajectory. Therefore, in the measurement of the actual oscillation amplitude of this type of optical distance measuring device, there is a possibility that a deviation occurs between the positional relationship predetermined for template creation and the actual positional relationship. The measurement accuracy of the dynamic amplitude depends on the installation accuracy of the optical distance measuring device main body and the flat plate by the operator or the like. In addition, since an operator or the like visually checks which scanning locus previously drawn on the template the outer edge of the projected scanning locus coincides, there is a possibility that a reading error may occur. As a result, the actual swing amplitude is measured using the template, the current value of the drive signal is adjusted according to the measurement result, or the design value is adjusted to the actual swing amplitude value to the optical distance measuring device. Even if it is reset and calibrated so that the swing angle around each axis of the movable part at each light projection timing becomes the intended angle, the calibration accuracy is determined by the operator at the actual swing amplitude measurement. There is a problem that it depends on work accuracy such as installation accuracy and reading accuracy.

  Therefore, the present invention has been made paying attention to such a problem, and the swing angle around each axis of the movable portion at each light projection timing is not affected by the work accuracy by the operator or the like. It is an object of the present invention to provide an optical distance measuring device that can be calibrated with high precision so that an intended angle is obtained.

The optical distance measuring device according to the first aspect of the present invention is an optical distance measuring device that scans pulsed light within a target region by swinging a movable part around two orthogonal axes, and measures the distance to the target object at each projection time. In the distance device, the unevenness of the surface shape is determined on the basis of each data of the measured distance with respect to the reference object , and at least one of the current values of the respective drive signals for swinging the movable part around each axis is obtained as the data until such within the threshold value error between the measured flatness and a known flatness of the object of the reference based on the changes in response to irregularities determination result.

The optical distance measuring device according to the second aspect of the present invention is an optical distance measuring device that scans pulsed light within a target region by swinging a movable part around two orthogonal axes, and measures the distance to the target object at each projection time. In the distance device, the unevenness of the surface shape is determined based on the point cloud data obtained by converting each data of the measured distance with respect to the reference object by the conversion parameter including the swing amplitude around each axis of the movable part. , said at least one of the oscillation amplitude of said transformation parameters until the error is such within threshold values between the measured flatness and a known flatness of the object of the reference based on the point group data, the unevenness determination result Change accordingly .

According to the optical distance measuring apparatus according to the present invention according to claim 1, the distance to the object of the reference measured every light projecting time, the unevenness determination of the surface shape of an object reference based on each data of distances this measurement And at least a current value of each drive signal that causes the movable part to swing around each axis until an error between the measured flatness of the reference object based on each data and the known flatness is within a preset threshold value. one of the by changing in response to irregularities determination result, it is possible to calibrate each oscillation amplitude of the actual machine, respectively. Therefore, according to the optical distance measuring apparatus according to the present invention according to claim 1, simply by appropriately setting the threshold value of the error between the actual measured flatness and a known flatness, real machine rocking in response to irregularities determination result Since the amplitude can be accurately adjusted to the target value, the swing angle around each axis of the movable part at each light projection time becomes the intended angle without being affected by the work accuracy by the operator or the like. In addition, an optical distance measuring device that can be calibrated with high accuracy can be provided.

According to the optical distance measuring device according to the second aspect of the present invention, the distance to the reference object is measured at each projection time, and the distance measured by the conversion parameter including the swing amplitude around each axis of the movable part. each data based on the conversion obtained was point cloud data, the unevenness determination of the surface shape of an object reference, at least one of the oscillation amplitude of the transformation parameters, the measured object reference based on the point cloud data until the error between the flatness and the known flatness is within the threshold value to be set in advance, by changing in response to irregularities determination result, the respective oscillation amplitude of the conversion parameters can calibrate it, respectively. Therefore, according to the optical distance measuring apparatus according to the present invention according to claim 2, only appropriately set the threshold value of the error between the measured flatness and a known flatness, the rocking of the transformation parameters in accordance with the unevenness determination result Since the value of the dynamic amplitude can be accurately adjusted to the value of each swing amplitude of the actual machine, the swing of the movable part around each axis at each projection time is not affected by the work accuracy by the operator etc. It is possible to provide an optical distance measuring device that can be calibrated with high accuracy so that each angle becomes an intended angle.

It is a block diagram which shows schematic structure of the optical ranging apparatus by 1st Embodiment. It is a figure which shows the structure of a two-dimensional galvanometer mirror as an optical scanning part of an optical distance measuring device. It is the schematic of the two-dimensional galvanometer mirror simplified in order to explain the incident light to the light reflecting surface, the scanning light reflected and scanned by the light reflecting surface, and the normal line of the light reflecting surface, (a) A perspective view, (b) is a view from the ZX plane side, and (c) is a view from the ZY plane side. It is a figure which shows the condition which is measuring the distance to a reference | standard object. It is an image figure of the point cloud image projected on ZY plane and ZX plane, (a) is a point cloud image projected on ZY plane, (b) is a point cloud image projected on ZY plane, convex shape, (c) ) Shows a case where the point cloud image projected on the ZX plane is concave, and (d) shows a case where the point cloud image projected on the ZX plane is convex. It is a flowchart which shows operation | movement of the optical ranging apparatus by the said 1st Embodiment. It is a block diagram of schematic structure of the optical ranging apparatus by 2nd Embodiment. It is a flowchart which shows operation | movement of the optical ranging apparatus by the said 2nd Embodiment. It is a block diagram of schematic structure of the optical ranging apparatus by 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of the optical distance measuring device according to the first embodiment of the present invention.
The optical distance measuring device 1 according to the present embodiment measures (measures) a distance to an object existing in the target region by two-dimensionally scanning the pulsed laser beam in the target region.

  As shown in FIG. 1, the optical distance measuring device 1 according to the present embodiment includes an optical scanning unit 2 capable of two-dimensional scanning, a driving unit 3 that drives the optical scanning unit 2, and laser light at a predetermined light projection timing. Distance from the light source unit 4 that projects light, the light receiving unit 5 that receives the reflected light of the projected light beam, the distance measuring unit 6 that measures the distance to the object that reflected the light beam, and the distance from the distance measuring unit 6 A data conversion unit 7 that converts data into point cloud data that indicates a position in a three-dimensional space using conversion parameters that are set in advance, and a determination unit 8 that performs a predetermined determination based on the point cloud data from the data conversion unit 7 And a setting changing unit 9 for changing and setting a preset driving current, a mode setting unit 10, an image generating unit 11, and a display unit 12, and the driving current can be changed and set.

  The optical scanning unit 2 is formed so that a movable part having a light reflecting surface (mirror) can swing around a first axis and a second axis orthogonal to each other, and the movable part swings, The light beam incident on the light reflecting surface can be two-dimensionally scanned (for example, Lissajous scanning) within the target region. As such an optical scanning unit 2, for example, a two-dimensional scanning semiconductor galvanometer mirror (hereinafter simply referred to as “two-dimensional galvanometer mirror”) described in Japanese Patent No. 2722314 proposed by the present applicant is used. it can.

FIG. 2 shows a configuration of a two-dimensional galvanometer mirror 20 as a specific example of the optical scanning unit 2.
As shown in FIG. 2, the two-dimensional galvanometer mirror 20 is arranged on the inner side of the frame-shaped fixed portion 21 and is movable outside and supported by a pair of first torsion bars 22, 22. An inner movable part 25 that is disposed inside the outer movable part 23 and is swingably supported by a pair of second torsion bars 24, 24 that are orthogonal to the first torsion bars 22, 22. Is provided.

  A light reflecting surface (mirror) 26 is formed at the central portion of the inner movable portion 25, and a first drive coil 27 and a second drive coil 28 are formed at the peripheral portions of the outer movable portion 23 and the inner movable portion 25, respectively. Yes. An end portion of the first drive coil 27 is connected to first electrode terminals 29 and 29 formed on the fixed portion 21, and an end portion of the second drive coil 28 is a second electrode terminal 30 formed on the fixed portion 21. , 30.

  In addition, a pair of first permanent magnets 31 and 31 for applying a magnetic field to the first drive coil 27 and a pair of second permanent magnets 32 and 32 for applying a magnetic field to the second drive coil 28 are opposed to each other with the fixed portion 21 interposed therebetween. Has been placed. The fixed portion 21, the first torsion bars 22, 22, the outer movable portion 23, the second torsion bars 24, 24, and the inner movable portion 25 are integrally formed from a semiconductor substrate.

  The two-dimensional galvanometer mirror 20 includes an outer movable portion 23 and an inner movable portion by currents flowing through the first drive coil 27 and the second drive coil 28 and magnetic fields generated by the first permanent magnets 31 and 31 and the second permanent magnets 32 and 32. Lorentz force acts on the portion 25, and as a result, the inner movable portion 25 swings around the first axis and the second axis. As the inner movable portion 25 swings in this way, the light beam incident on the light reflecting surface 26 is two-dimensionally scanned in the target region.

Further, the swing angle φ _x about the first axis and the swing angle φ _y about the second axis at each projection timing t _clk described later of the two-dimensional galvanometer mirror 20 are, for example, the first drive signal and the second drive. When it is assumed that there is no phase difference from the signal and each projection timing (time) t _clk is calculated with the scanning start time of the two-dimensional galvanometer mirror 20 as the start of time, for example, the following equations (1) and (2) It is represented by
Where φ _xmax is the first swing amplitude (maximum value) that is the swing amplitude around the first axis, φ _ymax is the second swing amplitude (maximum value) that is the swing amplitude around the second axis, and T _x Is the first oscillation cycle that is the oscillation cycle around the first axis, T _y is the second oscillation cycle that is the oscillation cycle around the second axis, and t _clk is the light beam projected from the light source unit 4 Each time is shown. Note that the first swing amplitude φ _xmax and the second swing amplitude φ _ymax are determined according to the current value of the supplied drive signals (first and second drive signals described later), and are measured by the optical distance measuring device. This is an important parameter for determining accuracy and the like. However, each actual swing amplitude (actual swing amplitude) determined according to the current value of the drive signal varies beyond the design allowable range due to, for example, a variation in the manufacturing process of the two-dimensional galvanometer mirror 20, In addition, there is a possibility of fluctuation due to a change with time of the optical scanning unit or the like. Therefore, measure the actual swing amplitude when a drive signal with a predetermined current value is supplied at the time of shipment or maintenance after shipment, and if the measured actual swing amplitude is outside the design allowable range It is necessary to adjust the current value of each drive signal so that each actual oscillation amplitude falls within the allowable design range. In addition, the first swing period T _x and the second swing period T _y are set in advance to periods based on drive frequencies of first and second drive signals described later.
In the following, the actual first oscillation amplitude φ _xmax determined according to the current value of the first drive signal is referred to as the actual first oscillation amplitude φ ′ _xmax, and the actual first oscillation amplitude φ ′ _xmax determined according to the current value of the second drive signal. The second oscillation amplitude φ _ymax is _referred to as an actual second oscillation amplitude φ ′ _ymax .

  FIG. 3 shows a state in which a light beam is projected onto the light reflecting surface 26 of the two-dimensional galvanometer mirror in a stationary state, and the light beam is reflected toward the target region. Here, as shown in FIG. 3A, the central axis of the first torsion bars 22 and 22 is the x-axis (first axis), and the central axis of the second torsion bars 24 and 24 is the y-axis (second axis). ) And the center point of the light reflecting surface 26 is defined as the origin O of the XYZ orthogonal coordinate system. That is, the normal line of the light reflecting surface 26 in a stationary state coincides with the Z axis of the XYZ orthogonal coordinate system. The incident light on the light reflecting surface 26, the normal line of the light reflecting surface 26, and the scanning light reflected and scanned by the light reflecting surface 26 will be described below.

First, the optical axis of light incident on the light reflecting surface 26 is adjusted in advance so that the light is projected from the light source unit 4 toward the center (origin O) of the light reflecting surface 26. For example, the incident light is set to be incident at a predetermined incident angle θ0 with respect to the normal line (that is, the Z axis) of the light reflecting surface 26 in a stationary state. For example, when projected on the ZX plane of incident light as shown in FIG. 3 (b), incident at an angle of θx0 respect to the normal, the incident light projected onto the ZY plane as shown in FIG. 3 (c) In this case, the incident angle is set to be incident at an angle of θy0 with respect to the normal line. Here, a unit incident light vector a in which incident light is expressed by a unit vector in an XYZ orthogonal coordinate system is expressed by the following equation (3).

Next, the normal of the light reflection surface 26 is at rest coincides with the Z-axis, but at the time of scanning (during rocking), the oscillation angle phi _x and the second axis of the first axis rocking its orientation is changed depending on the dynamic angle phi _y. A unit normal vector n representing the normal of the light reflecting surface 26 with a unit vector in the XYZ orthogonal coordinate system is a unit normal vector n ₀ in a stationary state and a rotation matrix R _x around the x axis (first axis). It is a fluctuation value determined based on the rotation matrix R _y around the y axis (second axis), and is represented by, for example, the following equation (4).
The unit normal vector _n 0 in the still state, x-axis of the rotation matrix _R x, rotation matrix _{R y} of the y axis is the (5) to (7) below, each represented.

The unit scanning light vector b (b _x , b _y , b _z ) in which the scanning light reflected and scanned by the light reflecting surface 26 is represented by a unit vector in the XYZ orthogonal coordinate system is expressed by, for example, the following equation (8). expressed.
The unit incident ray vector a (a _x , a _y , a _z ) in the above equation (3) and the unit normal vector n (n _x , n _y , n _z ) in the equation (4) are added to the equation (8). By substituting, the unit scanning ray vector b (b _x , b _y , b _z ) can be obtained.

  Returning to FIG. 1, the driving unit 3 drives the optical scanning unit 2 to swing. The drive unit 3 generates a first drive signal (for example, a pulse current) that swings the outer movable unit 23 and the inner movable unit 25 about the x axis, for example, near the resonance frequency around the x axis of the outer movable unit 23. Is supplied to the first drive coil 27 via the first electrode terminals 29, 29 at a drive frequency set in accordance with the frequency of the second drive signal (for example, the second drive signal (for example, swinging around the y axis) , Pulse current) is supplied to the second drive coil 28 via the second electrode terminals 30 and 30 at a drive frequency set in the vicinity of the resonance frequency around the y axis of the inner movable portion 25. The current values of the first and second drive signals and the drive frequencies around the x axis and the y axis are preset in advance.

The light source unit 4 emits a light beam (for example, pulsed laser light) at a predetermined light projection timing t _clk toward a light reflecting surface 26 formed on the inner movable unit 25 of the light scanning unit 2. It projects light, and includes a light source 41 and a light projecting optical system 42. The light projection timing t _clk is set in advance in the light source unit 4 so that, for example, each pixel assigned in the target region is irradiated with a light beam. The light projection timing t _clk is stored, for example, as a light projection time with the scanning start time of the optical scanning unit 2 as the start of time.

The light source 41 is, for example, a laser diode, and emits pulsed laser light by emitting light at a preset light projection timing t _clk .

  The light projecting optical system 42 makes the laser light emitted from the light source 41 preferable, and includes, for example, a collimator lens, and converts the laser light emitted from the light source 41 into parallel light. Then, the laser light projected from the light source unit 4 is reflected by the light reflecting surface 26 of the light scanning unit 2 and two-dimensionally scanned in the target area.

  The light receiving unit 5 is, for example, laser light projected from the light source unit 4 and reflected and scanned by the light reflecting surface 26 and reflected by an object existing in the target region, for example, laser light (that is, scanning light shown in FIG. 1). For example, a photosensor can be used. The light receiving unit 5 may receive the reflected light directly, or may receive the reflected light via the optical scanning unit 2 (light reflecting surface 26).

The distance measuring unit 6 measures the distance of the object based on the time difference between the light beam projection timing t _clk by the light source unit 4 and the light reception timing of the reflected light by the light receiving unit 5. The light timing t _clk and the light receiving timing of the light receiving unit 5 are input, and the distance to the object that reflected the light beam is measured based on the time difference between them (light flight time). The distance measurement by the distance measuring unit 6 is performed at each irradiation position (each pixel) in the target area, that is, for each light beam projection timing t _clk from the light source unit 4, and the measurement result (light projection timing). Each distance data L) is output to the image generator 11. The distance measuring unit 6 outputs the measurement result to a data conversion unit 71 and an image generation unit 11 described later.

The data converter 7 converts the distance data L for each projection timing from the distance measuring unit 6 into point cloud data indicating a position in a three-dimensional space using a preset conversion parameter. In the embodiment, a data conversion circuit 71 that converts distance data L from the distance measuring unit 6 and a parameter storage unit 72 that stores conversion parameters are included. The conversion parameters include, for example, the light projection timing t _clk , the unit incident light vector a that is a unit vector of laser light from the light source unit 4 toward the light reflecting surface 26, the first oscillation amplitude φ _xmax , and the second oscillation. It _consists of an amplitude φ _ymax , a first oscillation period T _x, and a second oscillation period T _y . This point group data is, for example, data in an XYZ orthogonal coordinate system. From the arrangement of the point cloud data, the shape of the surface of the object measured by the distance measuring unit 6 is known.

The data conversion circuit 71 is a circuit that receives the distance data L for each projection timing output from the distance measuring unit 6 and converts the distance data into, for example, point group data in an XYZ orthogonal coordinate system. Specifically, the data conversion circuit 71 first converts the conversion parameters (t _clk , φ _xmax , φ _ymax , T _x , T _y ) preset in the parameter storage unit 72, and the above-described formula (1) and Using the equation (2), the first swing angle φ _x and the second swing angle φ _y for each light projection timing are obtained. Next, a unit normal vector n for each light projection timing is obtained by using the obtained first rocking angle φ _x and second rocking angle φ _y and Expressions (4) to (7). Then, the obtained unit normal vector n and the unit incident ray vector a of the equation (3) are substituted into the equation (8), and the unit scanning ray vector b (b _x , b _y , b _{z for} each projection timing is obtained. ) Finally, the obtained unit scanning ray vector b (b _x , b _y , b _z ) is multiplied by L using the distance data L for each light projection timing from the distance measuring unit 6 to obtain an XYZ orthogonal coordinate system. Point cloud data indicating the position in space is obtained. This point cloud data is output to the determination unit 8 and the image generation unit 11.

The parameter storage unit 72 includes, for example, a projection timing t _clk , a unit incident light vector a (a _x , a _y , a _z ), a first oscillation amplitude φ _xmax, and a second oscillation as conversion parameters. Each data of the dynamic amplitude φ _ymax , the first swing period T _x , and the second swing period T _y is stored. Design values are stored as initial values of each data.

Here, the actual light emitting timing t _clk during scanning, the first oscillating period T _x, the second oscillating period T _y, for example, set with high accuracy by the accuracy of the system clock frequency in the optical distance measuring device The values (design values) stored in the parameter storage unit 72 are substantially the same. Further, the direction in which the laser light travels toward the light reflecting surface 26 can be adjusted with high accuracy by, for example, manufacturing accuracy of components that position the light source unit 4 and the movable unit (the outer movable unit 23 and the inner movable unit 25). Therefore, the actual unit incident light vector a (a _x , a _y , a _z ) also substantially matches the value (design value) stored in the parameter storage unit 72. As described above, the light projection timing t _clk stored in the parameter storage unit 72, the incident light vector a (a _x , a _y , a _z ), the first oscillation period T _x, and the second oscillation period T _{For the y} data, the error from the actual product value is negligible.

On the other hand, the actual first oscillation amplitude φ ′ _xmax and the actual second oscillation amplitude φ ′ _ymax fluctuate beyond the allowable design range due to changes with time of the two-dimensional galvanometer mirror 20 as described above. In some cases, the amount of variation is not negligible when compared with the above-described projection timing t _clk , the fluctuation periods T _x , T _y, and the unit incident light vector a (a _x , a _y , a _z ). It may become so large. Therefore, the first swing amplitude φ _xmax and the second swing amplitude φ _ymax stored as design values in the parameter storage unit 72 are the actual first swing amplitude φ ′ _xmax and the actual second swing amplitude φ ′. _{In some cases} , the error from _ymax cannot be ignored. Accordingly, only the first oscillation amplitude φ _xmax and the second oscillation amplitude φ _ymax are data whose actual values are uncertain among the conversion parameters.

  The determination unit 8 has reference feature data of a surface shape of a reference object whose three-dimensional surface shape is known in advance, and the distance for each light projection timing obtained by measuring the distance to the reference object by the distance measuring unit 6 Based on the point cloud data for the reference object obtained by converting the data L by the data converter 7, the surface shape feature is measured, and the error between the measured feature data and the reference feature data is within a preset threshold. It is determined whether or not. The determination unit 8 outputs the determination result to the setting change unit 9.

When the determination unit 8 determines that the error between the measured feature data and the reference feature data is greater than a preset threshold, the setting change unit 9 is preset in the drive unit 3 and the actual first swing amplitude φ. ' _xmax and actual second oscillation amplitude φ' At least one of the current values of the first and second drive signals that determine the value of _y is changed until the determination unit 8 determines that the error is within the threshold value. It can be set. For example, the setting change unit 9 is not set so as to change and set the current value of each drive signal in the initial state, and the first and second preset values are set unless the mode setting unit 10 sets the calibration mode to be described later. The current value of the second drive signal is not changed and set.

The mode setting unit 10 can be switched between a calibration mode in which change setting is performed by the setting change unit 9 and a normal distance measurement mode in which the distance to the object is measured by the distance measurement unit 6. In the embodiment, the calibration mode means that the current values of the first and second drive signals set in advance are changed, and the values of the first oscillation amplitude φ _xmax and the second oscillation amplitude φ _ymax of the conversion parameters are actually _realized . In this mode, the first swing amplitude φ ′ _xmax and the _actual second swing amplitude φ ′ _ymax are accurately adjusted. Therefore, when the operator or the like of the apparatus calibrates the actual first oscillation amplitude φ ′ _xmax and the actual second oscillation amplitude φ ′ _ymax , the apparatus is set to the calibration mode by the mode setting unit 10 and normal distance measurement is performed. When performing, the normal distance measurement mode may be set.

  FIG. 4 shows a situation where the distance to the reference object is being measured. In the present embodiment, as shown in FIG. 4, the reference object is an object (for example, a wall) whose surface shape is a plane. In the present embodiment, specifically, the determination unit 8 has reference flatness data as the reference feature data, measures the flatness as the feature of the surface shape of the reference object, and the measured flatness data and the reference It is determined whether or not the flatness data error is within a predetermined threshold. The setting changing unit 9 is a case where the determining unit 8 determines that the error between the measured flatness data and the reference flatness data is larger than the threshold value, and the surface shape based on the point cloud data is compared with the optical scanning unit 4. When the shape is convex and convex (in the case of FIGS. 5A and 5C), the current value of the change setting, that is, the current values of the first and second drive signals in this embodiment, When at least one is reduced by a predetermined amount and is concave with respect to the optical scanning unit 4 (in the case of FIGS. 5B and 5D described later), the first and second drive signals Is configured to increase at least one of the current values by a predetermined amount. In the above description, the reference object is, for example, a wall, but may be a floor.

  Further, when the setting change unit 9 changes the current values of the first and second drive signals, specifically, according to the surface shape unevenness determination based on the point cloud data by the determination unit 8, for example, first, When the current value of the first drive signal is changed and the determination unit 8 determines again that the flatness is greater than the threshold value, the current value of the second drive signal is changed according to the unevenness determination by the determination unit 8. Then, the drive current change is repeated until it is determined that the error between the measured flatness data after the drive current change and the reference flatness data is within a threshold. Note that the order of changing the drive current may be reversed, and the current value of the second drive signal may be changed first. Moreover, not only when changing one by one as mentioned above, but both drive currents may be changed at once.

  The image generation unit 11 generates a general distance image (not shown) for the target region based on the distance measured by the distance measurement unit 6. The distance image is generated, for example, so that the color is different for each distance measured at each irradiation position of the light beam at each projection timing. The distance image generated by the image generation unit 11 is output to the display unit 12. The display unit 12 includes a display and displays the distance image output from the image generation unit 11. It is possible to visually recognize the distance to the object, the change in the posture of the object, and the like as well as the object existing in the target region can be recognized by the distance image.

  In the present embodiment, the image generation unit 11 can further generate a three-dimensional point cloud image for an object in the target region based on the point cloud data from the data conversion unit 7. Then, the three-dimensional point cloud image generated by the image generation unit 11 is output to the display unit 12 and displayed on the display. With this point cloud image, the shape of the surface of the object can be visually confirmed.

  FIG. 5A to FIG. 5D are image diagrams of point cloud images projected on the ZY plane and the ZX plane. 5A shows a concave shape of the point cloud image projected on the ZY plane, FIG. 5B shows a convex shape of the point cloud image projected on the ZY plane, and FIG. 5C shows a point cloud image projected on the ZX plane. Is a concave shape, and FIG. 5D is an image diagram when the point cloud image projected onto the ZX plane is convex. In FIGS. 5A to 5D, the projected point group images are represented by lines for the sake of simplification, but in reality, the points are drawn discretely.

  Next, the actual oscillation amplitude calibration operation of the optical distance measuring device 1 having the above configuration will be described with reference to FIG. In the following description, the optical distance measuring device 1 is installed in front of a reference object (for example, a wall) whose surface shape is known by the operator of the device, etc. It is assumed that the apparatus is set to the calibration mode by the operation of the mode setting unit 10 according to the above, and that the preliminary preparation for calibration is completed (STEP 0).

First, the distance measuring operation for the reference object will be described. The drive unit 3 swings the inner movable unit 25 in a two-dimensional direction by supplying first and second drive signals to the first and second drive coils 27 and 28 at respective drive frequencies that are initially set. Let At the same time, the light source unit 4 projects a pulsed laser beam on the light reflecting surface 26 of the inner movable unit 25 that swings in a two-dimensional direction at a preset projection timing t _clk . The laser light reflected and scanned by the light reflecting surface 26 is two-dimensionally scanned in the target region, reflected by a reference object (wall or the like) existing in the target region, and received by the light receiving unit 5. Here, the distance measuring unit 6 measures the distance to the reference object for each light projection timing based on the time difference between the laser light projection timing and the light reception timing (STEP 1). Then, the distance measurement unit 6 outputs the measurement result (distance data L for each light projection timing) to the data conversion circuit 71 and the image generation unit 11. The image generation unit 11 generates a distance image based on the measurement result from the distance measurement unit 6. Then, the generated distance image is displayed on the display unit 12 (STEP 2). Next, the data conversion circuit 71 converts the distance data L for each light projection timing from the distance measuring unit 6 into point group data in the XYZ orthogonal coordinate system (STEP 3). The data conversion circuit 71 outputs the calculated point cloud data to the determination unit 8 and the image generation unit 11 (STEP 4). The determination unit 8 measures the flatness of the surface of the reference object from the arrangement of the point cloud data, and determines whether an error between the measured flatness data and the preset reference flatness data is within a predetermined threshold. Determine (STEP 5). Here, when it is determined that the error between the measured flatness data and the reference flatness data is larger than the threshold value (NO in STEP5), the process proceeds to STEP6. Here, when it is determined by the determination unit 8 that the surface shape based on the point cloud data is a convex shape with respect to the optical scanning unit, the setting change unit 9 stores, for example, the first stored in the drive unit 3. If at least one of the current values of the first and second drive signals is reduced by a predetermined amount and it is determined that the optical scanning unit has a concave shape, the first stored in the drive unit 3 is stored. At least one of the current values of the second drive signal is increased by a predetermined amount (STEP 6). Then, returning to STEP 1, the operations from STEP 1 to STEP 5 are performed, and STEP 1 to STEP 6 until it is determined that the error between the measured flatness data after changing the current value and the reference flatness data is within the threshold value (STEP 5 affirmative). Repeat the operation. If the error is within the threshold value (YES at STEP 5), the process proceeds to STEP 7. At this time, if the threshold is appropriately set, the actual first swing amplitude φ ′ _xmax and the actual second swing amplitude φ ′ _ymax substantially coincide with the target value set in the parameter memory 2. In this way, each swing amplitude corresponding to the current value of each drive signal is calibrated with each swing amplitude of the conversion parameter as a target, and the calibration is completed (STEP 7).

As described above, according to the optical distance measuring device 1 according to the present embodiment, the distance data from the distance measuring unit 6 when the distance to the reference object is measured is converted into point cloud data using the preset conversion parameter. Based on this point cloud data, the surface shape feature of the reference object is measured, and the preset second feature is set until the error between the measured feature data and the preset reference feature data is within a preset threshold. By changing at least one of the current values of the first drive signal and the second drive signal, the actual first swing amplitude φ ′ _xmax is set with the first swing amplitude φ _xmax and the second swing amplitude φ _ymax of the conversion parameters as targets. _{And the actual} second oscillation amplitude φ ′ _ymax can be calibrated. Therefore, according to the optical distance measuring device according to the present embodiment, the target value of each actual swing amplitude is set as a conversion parameter, and an error threshold value between the measured characteristic data and the reference characteristic data is set appropriately. Since each actual swing amplitude can be accurately adjusted to the target value, the swing angle around each axis of the movable part at each light projection timing is not affected by the work accuracy by the operator or the like. Therefore, it is possible to provide an optical distance measuring device that can be calibrated with high accuracy so that the angle becomes the same angle.

  Further, according to the optical distance measuring device according to the present invention, for example, when each actual oscillation amplitude has deviated from the design allowable range due to the temporal change of the optical scanning unit, or around the optical distance measuring device at the time of calibration before shipment. Even if the temperature of the optical distance measurement device and the temperature of the optical distance measuring device after shipment are different, the actual swing amplitude is designed by fine-tuning the drive current value appropriately according to changes over time and temperature differences. Calibration can be performed so that it is within the allowable range.

Next, an optical distance measuring device according to a second embodiment of the present invention will be described.
FIG. 7 is a partial block diagram showing a schematic configuration of the optical distance measuring device according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the element same as 1st Embodiment of FIG. 1, description is abbreviate | omitted, and only a different part is demonstrated. In the present embodiment, the _values of the first oscillation amplitude φ _xmax and the second oscillation amplitude φ _ymax of the conversion parameter are _accurately set to the values of the actual first oscillation amplitude φ ′ _xmax and the actual second oscillation amplitude φ ′ _ymax. A configuration that can be combined well will be described.

In this embodiment, the setting change unit 9 determines that the error between the measured feature data and the reference feature data is larger than a preset threshold value by the determination unit 8, and the first swing amplitude φ _xmax of the conversion parameter. In _addition , at least one of the second swing amplitude φ _ymax can be changed and set until the determination unit 8 determines that the error is within the threshold. For example, the setting change unit 9 is not set so as to change and set each oscillation amplitude of the conversion parameter in the initial state, and unless the mode setting unit 10 sets the calibration mode, each oscillation amplitude of the conversion parameter is set. It is configured not to be changed. In the present embodiment, the calibration mode _{refers to} the values of the first oscillation amplitude φ _xmax and the second oscillation amplitude φ _ymax of the conversion parameters, the actual first oscillation amplitude φ ′ _xmax and the actual second oscillation amplitude φ ′. _{In this} mode, the _ymax value is accurately adjusted.

  The setting changing unit 9 is a case where the determining unit 8 determines that the error between the measured flatness data and the reference flatness data is larger than the threshold value, and the surface shape based on the point cloud data is compared with the optical scanning unit 4. When the shape is convex (in the case of FIGS. 5 (a) and 5 (c)), at least one of the values to be changed or set, that is, each oscillation amplitude of the conversion parameter in this embodiment, is set. When it is reduced by a predetermined amount and is concave with respect to the optical scanning unit 4 (in the case of FIGS. 5B and 5D described later), at least one of the swing amplitudes of the conversion parameter Is increased by a predetermined amount.

Further, when the setting change unit 9 changes each swing amplitude of the conversion parameter, specifically, according to the surface shape unevenness determination based on the point cloud data by the determination unit 8, for example, first, the first swing is performed. When the dynamic amplitude φ _xmax is changed and the determination unit 8 determines again that the flatness is larger than the threshold value, the second swing amplitude φ _ymax is changed according to the unevenness determination by the determination unit 8. Then, the change of each swing amplitude of the conversion parameter is repeated until it is determined that the error between the measured flatness data after changing the conversion parameter (each swing amplitude) and the reference flatness data is within the threshold value. Note that the order of changing each swing amplitude is opposite to the above, and the second swing amplitude φ _ymax may be changed first. Moreover, not only when changing one by one as described above, both swing amplitudes may be changed at once.

In addition, when all the values of the conversion parameters are substantially the same as the actual machine, the distance data for each projection timing obtained by measuring the distance to the reference object by the distance measurement unit is converted by the data conversion unit. Based on the point cloud data for the reference object, the measured flatness data measured by the determination unit and the reference flatness data should substantially match. Further, among the conversion parameters, the light projection timing, the oscillation period, and the incident light vector can generally be set in advance so as to substantially match the values in the actual machine, but the first oscillation amplitude φ _xmax and the first For example, since the fluctuation amplitude φ _ymax varies due to, for example, manufacturing variation of the two-dimensional galvanometer mirror or a change with time, only the fluctuation amplitude is the only data in the conversion parameter whose value in the actual machine is uncertain. Therefore, as described above, when each swing amplitude of the conversion parameter is changed and the characteristic measured by the determination unit and the reference feature match, the first and second swing amplitudes of the converted conversion parameter are changed. Is substantially the same as each actual oscillation amplitude.

  Next, the calibration operation of the optical distance measuring device 1 having the above configuration will be described with reference to FIG. In the following description, the optical distance measuring device 1 is installed in front of a reference object whose surface shape is known (for example, a wall) by an operator of the device, etc., and mode setting by the operator etc. after activation (power ON) The operation will be described on the assumption that the apparatus is set to the mode mode by the operation of the unit 10 and the preliminary preparation for calibration is completed (STEP 0). Since the operations of STEP other than STEP 6 'are the same as those in the first embodiment, the description will be simplified.

First, the distance to the reference object is measured at each light projection timing (STEP 1). Then, the distance measurement unit 6 outputs the measurement result to the data conversion circuit 71 and the image generation unit 11. The image generation unit 11 generates a distance image. The display unit 12 displays the distance image (STEP 2). Next, the data conversion circuit 71 converts the distance data L from the distance measuring unit 6 into point group data in the XYZ orthogonal coordinate system, and outputs the point group data to the determination unit 8 and the image generation unit 11 (STEP 3, 4). The determination unit 8 measures the flatness of the surface of the reference object from the arrangement of the point cloud data, and determines whether the error between the measured flatness data and the reference flatness data is within a threshold value. Here, when it is determined that the error is larger than the threshold (NO in STEP 5), the process proceeds to STEP 6 ′. When the determination unit 8 determines that the surface shape based on the point cloud data is convex with respect to the optical scanning unit, the setting change unit 9 uses the first fluctuation amplitude φ _xmax and the second fluctuation of the conversion parameter. If at least one of the dynamic amplitudes φ _ymax is reduced by a predetermined amount and it is determined that the shape is concave with respect to the optical scanning unit, the first swing amplitude φ _xmax and the second swing of the conversion parameter are determined. At least one of the amplitudes φ _ymax is increased by a predetermined amount (STEP 6 ′). Then, returning to STEP 1, the operations from STEP 1 to STEP 5 are performed, and STEP 1 to STEP 6 until it is determined that the error between the measured flatness data after the conversion parameter change and the reference flatness data is within the threshold value (YES in STEP 5). Repeat the operation. If the error is within the threshold value (YES at STEP 5), the process proceeds to STEP 7. At this time, if the threshold value is set appropriately, the _values of the first swing amplitude φ _xmax and the second swing amplitude φ _ymax of the converted conversion parameters after the change are the actual first swing amplitude φ ′ _xmax and the actual first swing amplitude φ ′ _xmax. 2 substantially coincides with the value of the swing amplitude φ ′ _ymax . In this way, the value of each oscillation amplitude of the conversion parameter is matched with the value of each actual oscillation amplitude with high accuracy, and the calibration is completed (STEP 7).

Thus, according to the optical distance measuring device 1 according to the present embodiment, unlike the optical distance measuring device 1 according to the invention according to the first embodiment, the first oscillation amplitude φ _xmax and the second oscillation amplitude φ of the conversion parameters. _{By changing} at least one of _ymax until the error between the measured feature data and the preset reference feature data of the surface shape of the reference object falls within a preset threshold, the first and second fluctuations of the actual machine are changed. With the dynamic amplitude as a target, the first and second oscillation amplitudes of the conversion parameters can be calibrated. Therefore, according to the optical distance measuring device 1 according to the present embodiment, the value of each oscillation amplitude of the conversion parameter is changed to each actual oscillation only by appropriately setting an error threshold value between the measured characteristic data and the reference characteristic data. Since it can be accurately adjusted to the value of the dynamic amplitude, the swing angle around each axis of the movable portion at each light projection timing becomes the intended angle without being affected by the work accuracy by the operator or the like. In addition, an optical distance measuring device that can be calibrated with high accuracy can be provided.

In the first embodiment described above, the setting change unit 9 determines that the error between the measured feature data and the reference feature data is greater than the threshold value by the determination unit 8 as in the second embodiment. As a configuration having a configuration in which at least one of the first oscillation amplitude φ _xmax and the second oscillation amplitude φ _ymax of the conversion parameter can be changed and set until the determination unit 8 determines that the error is within the threshold value. Also good. In this case, as in the third embodiment of the present invention shown in FIG. 9, a change target selection unit 13 capable of selecting and switching a target to be changed and set by the setting change unit 9 is provided. As a result, when the mode setting unit 10 sets the calibration mode, the setting change unit 9 sets the change setting target by the change target selection unit 13 as the first swing amplitude φ _xmax and the second swing of the conversion parameter. The amplitude φ _ymax or the preset current values of the first and second drive signals can be switched and the calibration method can be freely selected. As shown in FIG. 9, the mode setting unit 10 has been described as being provided separately from the change target selection unit 13, for example. However, the present invention is not limited to this, but the function of the change target selection unit 13 is not illustrated. In addition, the change target selection unit 13 may be configured integrally. In this case, the mode setting unit 10 includes, for example, a normal distance measurement mode in which the distance to the object is measured by the distance measurement unit 6 and a drive current change mode in which the current values of the first and second drive signals set in advance are changed. And a conversion parameter change mode for changing each oscillation amplitude of the conversion parameter.

  In the description of all the above embodiments, the reference object has been described in the case where the surface shape is a plane. For example, the surface shape of the reference object may be a spherical surface. In this case, the feature amount of the surface shape is For example, the sphericity and the curvature of the surface may be calculated.

  Further, in the description of all the above embodiments, the case where the image generation unit 11 and the display unit 12 are provided has been described, but the image generation unit 11 and the display unit 12 may not be provided.

  In the description of all the above embodiments, the optical scanning unit 2 has been described by the case where it is configured by the two-dimensional galvanometer mirror 20 in which the outer movable unit and the inner movable unit are integrally formed. However, two well-known one-dimensional galvanometer mirrors may be used and arranged so that the respective swing axes are orthogonal to each other.

DESCRIPTION OF SYMBOLS 1 ... Optical distance measuring device 2 ... Optical scanning part 3 ... Drive part 4 ... Light source part 5 ... Light receiving part 6 ... Distance measuring part 7 ... Data conversion part 8 ... Determination part 9 ... Setting change part 10 ... Mode setting part 11 ... Image Generation unit 12 ... display unit 13 ... change target selection unit 20 ... two-dimensional galvanometer mirror (optical scanning unit)
23, 25 ... Movable part (outer movable part, inner movable part)
26: Light reflecting surface

Claims (7)

In the optical distance measuring device that swings the movable part around two orthogonal axes, scans the pulsed light within the target area, and measures the distance to the target object at each projection time ,
The unevenness of the surface shape is determined based on each data of the measured distance with respect to the reference object,
At least one of the current values of the drive signals for oscillating the movable portion to each axis, that Do within the threshold value error between the measured flatness and a known flatness of the object of the reference based on each data Until now, the optical distance measuring device is changed according to the unevenness determination result . In the optical distance measuring device that swings the movable part around two orthogonal axes, scans the pulsed light within the target area, and measures the distance to the target object at each projection time ,
The unevenness of the surface shape is determined based on point cloud data obtained by converting each data of the measured distance with respect to a reference object by a conversion parameter including a swing amplitude around each axis of the movable part,
Depending on the conversion parameters the at least one of the oscillation amplitude of, until the error is such within threshold values between the measured flatness and a known flatness of the object of the reference based on the point cloud data, unevenness determination result Optical ranging device to change . The movable portion has a light reflecting surface, and is configured to be swingable around first and second axes orthogonal to each other.
An optical scanning unit that two-dimensionally scans the light beam incident on the light reflecting surface by swinging the movable unit within the target region;
A first drive signal for swinging the movable part about the first axis and a second drive signal for swinging the movable part about the second axis are output to the optical scanning part to swing the movable part. A drive unit for dynamic driving;
A light source unit that projects a light beam toward the light reflecting surface;
A light receiving unit that receives the reflected light reflected by the target object that is projected from the light source unit and reflected and scanned by the light reflecting surface in the target region;
A distance measuring unit that measures a distance to the target object based on a time difference between a light projecting time of the light beam and a light receiving time of reflected light by the light receiving unit;
With
The light source unit is configured to project the light beam at each preset projection time,
The preset light projection time, the incident light vector of the light beam from the light source portion toward the light reflecting surface, the first oscillation amplitude around the first axis, and the second oscillation around the second axis are preset. A data conversion unit that converts the distance data for each projection time from the distance measurement unit into point cloud data indicating a position in a three-dimensional space using a conversion parameter including a dynamic amplitude;
The light projection obtained in advance by having reference flatness data as reference feature data of the surface shape of the reference object having a known three-dimensional shape, and measuring the distance to the reference object by the distance measuring unit Based on the point cloud data for the reference object obtained by converting the distance data for each time by the data conversion unit, the flatness as the feature degree of the surface shape of the reference object is measured, and this measured plane A determination unit for determining whether an error between the degree data and the reference flatness data is within a preset threshold;
When the determination unit determines that the error is larger than the threshold value, at least one of the current values of the first and second drive signals that are set in advance and determine actual values of the first and second swing amplitudes Until the determination unit determines that the error is within the threshold value,
The optical distance measuring device according to claim 1, comprising: The movable portion has a light reflecting surface, and is configured to be swingable around first and second axes orthogonal to each other.
An optical scanning unit that two-dimensionally scans a light beam incident on the light reflecting surface by swinging the movable unit within a target region;
A first drive signal for swinging the movable part about the first axis and a second drive signal for swinging the movable part about the second axis are output to the optical scanning part to swing the movable part. A drive unit for dynamic driving;
A light source unit that projects a light beam toward the light reflecting surface;
A light receiving unit that receives the reflected light reflected by the target object that is projected from the light source unit and reflected and scanned by the light reflecting surface in the measurement target region;
A distance measuring unit that measures a distance to the target object based on a time difference between a light projecting time of the light beam and a light receiving time of reflected light by the light receiving unit;
With
The light source unit is configured to project the light beam at each preset projection time,
The preset light projection time, the incident light vector of the light beam from the light source portion toward the light reflecting surface, the first oscillation amplitude around the first axis, and the second oscillation around the second axis are preset. A data conversion unit that converts the distance data for each projection time from the distance measurement unit into point cloud data indicating a position in a three-dimensional space using a conversion parameter including a dynamic amplitude;
The light projection obtained in advance by having reference flatness data as reference feature data of the surface shape of the reference object having a known three-dimensional shape, and measuring the distance to the reference object by the distance measuring unit Based on the point cloud data for the reference object obtained by converting the distance data for each time by the data conversion unit, the flatness as the feature degree of the surface shape of the reference object is measured, and this measured plane A determination unit for determining whether an error between the degree data and the reference flatness data is within a preset threshold;
When the determination unit determines that the error is larger than the threshold, at least one of the first and second oscillation amplitudes of the conversion parameter is determined by the determination unit and the error is determined to be within the threshold. A setting changer that can be changed until
The optical distance measuring device according to claim 2, comprising: When the determination unit determines that the error is larger than the threshold, the setting change unit determines at least one of the first and second swing amplitudes of the conversion parameter, and determines that the error is the threshold by the determination unit. Has a configuration that can be changed and set until it is determined that
The optical distance measuring device according to claim 3 , further comprising a change target selection unit capable of selecting and switching the target to be changed and set by the setting change unit. The mode setting unit can be switched between a calibration mode in which the setting change unit performs the change setting and a normal distance measurement mode in which the distance measurement unit measures the distance to the target object. Item 6. The optical distance measuring device according to any one of Items 3 to 5 . Surface configuration of the object of the reference is a plane,
The determination unit includes a reference flatness data as the reference feature of data, and measuring the flatness as a feature of the surface shape of the object of the reference, an error between this actual flatness data the reference flatness data Whether or not is within a preset threshold,
The setting change unit is a case where the determination unit determines that the error is larger than a threshold value, and the surface shape based on the point cloud data is determined to be a convex shape with respect to the optical scanning unit Decreases the target value of the change setting by a predetermined amount, and when it is determined that the surface shape based on the point cloud data is concave with respect to the optical scanning unit, the change setting 7. The optical distance measuring device according to claim 3 , wherein the target value can be increased by a predetermined amount.