KR101565481B1 - Multipoint snow depth measurement apparatus - Google Patents

Abstract

A snowfall amount measuring method and a snowfall amount measuring apparatus using a single laser distance meter are provided. A snowfall measuring apparatus according to the present invention comprises a step motor including a rotating shaft, a laser distance measuring instrument tilted at a predetermined angle to a plane perpendicular to the rotating shaft of the stepping motor, And controlling the laser range finder to measure distances at a plurality of target points. According to the present invention, since the laser distance measuring instrument is slightly attached to the axis of the step motor and rotates, it becomes possible to measure the amount of snow on a plurality of points scattered along a circle on the eye surface.

Description

[0002] Multipoint snow depth measurement apparatus [0003]

The present invention relates to a snowfall measuring apparatus, and more particularly, to a device for measuring the depth of snow (snowfall) accumulated on the ground more practically and reliably.

With the development of the Internet and communication networks, meteorological data measurement has become more automated by using computers, communication equipment, and sensors.

The measurement of snowfall is one of the areas of high interest in automated measurement due to the importance and necessity of automation, especially when the location of the target location is remote from the weather center or residential area.

Because of this, many manufacturers have developed snowfall measurement equipment based on a variety of technologies, including laser distance meters, ultrasonic measurements, visual signal (image signal) processing, and mechanical measurement methods.

Snowfall measurement equipment based on currently available or proposed laser distance measurement techniques use one or two lasers and associated receivers (eg, Korean Patent No. 348574). Because of this, complaints are raised regarding inconsistent measurement results and vulnerabilities to various environments in actual measurement sites. For example, if the target point of the laser transmitter is obscured or obstructed by foreign matter such as leaves, dust, or snowflakes flying, the measurement result will not represent the desired information about the snowfall at that point. Also, if only one or two points are measured at an area of 1 meter x 1 meter, the measured value can not represent the total area.

Models based on ultrasound signals are widely used, but these models have weaknesses in terms of measurement accuracy due to the nature of the ultrasound signal itself and variations due to temperature variations.

Some models based on image processing use various signal / image processing techniques to recognize the position of the point representing the depth of the eye. One of the problems with these models is caused by unclear or fuzzy images due to snow or ice formed at a target point, such as a scaled rod, and a large number of light sources in a straight line. Another problem is that when it gets too dark, it needs to be properly illuminated. (E.g. U.S. Patent Application Publication No. 2011/0219868)

Methods based on mechanical measurements have potential problems of mechanical malfunction due to cold weather, strong winds, and the formation of ice. In addition, there is a possibility that the measurement result may vary significantly depending on the type of eye. For example, if the eyes are soft, the eye-contacting mechanism may press the eyes and affect the measurement data.

US Patent No. 6,044,699), or a method of measuring a wide area using a GPS signal (e.g., U.S. Patent No. 5,761,095) by measuring the amount of snow by substituting water with a container Although there are several studies on these, these methods relate to applications different from those to which the solution provided by the present invention is applied.

In order to solve these problems while maintaining the required accuracy and consistency, a laser distance meter based on a structure having a plurality of laser emitters and receivers may be tried. As would be expected, this method will be more expensive, especially when it is necessary to measure many points to meet the requirements for real-life applications.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a snowfall measuring apparatus which uses a single laser distance measuring instrument and is less influenced by the surrounding environment and has high reliability of measurement results.

The present invention proposes an apparatus for solving conventional problems by allowing a multi-point measurement of snowfall using a single laser distance meter combined with a stepper motor. The laser range finder is tilted at a certain angle to the stepper motor so that the laser signal emitted from the laser range finder at different points of view (or at different angles of rotation) points to different points on the surface of the eye or on the circle Respectively. This method makes it possible to measure snowfall on a number of points scattered along a circle on the eye surface. The size of the circle (ellipse) may vary depending on the distance between the laser distance meter and the eye surface, and the angle between the direction pointed by the laser distance meter and the axis of the stepper motor.

According to another aspect of the present invention, a stopper mechanism is used to prevent cutting or breaking of a cable connecting the controller unit and a rotating laser distance measuring instrument.

According to another aspect of the present invention, a position control mechanism based on an infrared or visible light emitting element and a phototransistor is used.

The present invention also provides a method of calibrating a device of the present invention. A box or jig is used to lift the target area by a predetermined height so as to be able to calculate the angle of arrival at each point of the circle on the ground or eye surface in the calibration procedure.

According to another aspect of the present invention, the proposed method calculates the average depth of the area defined by this circle. By filtering and further processing the acquired measurement data along the path, the abnormal measurement is discarded and the average is calculated with only meaningful measurement data to yield the final result.

According to another aspect of the present invention, transmission and reception of data and transmission of power between the control section and the laser range finder are performed wirelessly.

According to the present invention, since the laser range finder for emitting the laser beam is slightly inclined to the axis of the step motor, it becomes possible to measure the amount of snow on a plurality of points scattered along a circle on the eye surface. It is also possible to detect the erroneous measurement data over time and isolate the affected point (s) until the erroneous operation is repaired. Also, because a larger number of samples can be obtained for a circle (ellipse) shape on the eye surface, the average snowfall measured may be closer to the actual snowfall value as compared to other methods based on one or less samples. Further, in the present invention, the position of the measurement point can be easily changed if a point showing an abnormal result is found. According to the present invention, it is possible to change the measurement sensitivity. Further, according to the present invention, only a low-cost device including one laser distance meter and a step motor is used, so that it can be made in a relatively small housing with high cost efficiency and lower complexity.

1 is a conceptual diagram showing a configuration of a snowfall measuring apparatus of the present invention.
2 is an explanatory view for explaining a laser beam sending operation of the snowfall measuring apparatus of the present invention.
3 is a view for explaining the principle of measurement of snowfall amount of the snowfall amount measuring apparatus of the present invention.
4 is a view for explaining an operation of the snowfall measuring apparatus of the present invention for measuring snowfall along a circle on the snow surface.
5 is an example of a measurement data graph having a projection value and a depression value.
6 is a view for explaining a method of performing the calibration of the present invention using a tool having a height Lref for a measurement performed at a given time t.
7 is a flowchart illustrating a calibration process according to an exemplary embodiment of the present invention.
8 is a view showing a multi-point snowfall measuring apparatus housed in a protective housing.
Fig. 9 shows a stopper mechanism for preventing the cable connecting the laser range finder and the step motor from being disconnected.
Fig. 10 shows the mechanism of the stopper viewed from another point of view.
Figure 11 shows an optical sensor scheme for the repositioning method of the present invention.
12 is a flowchart for explaining the motor repositioning process.
Fig. 13 is a diagram showing how the reset algorithm uses the circular positions when the step motor rotates once. Fig.
14 is a block diagram showing a configuration of an embodiment for wirelessly transmitting power and data between a control unit and a laser distance measuring instrument.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following description, the "depth" of the eye means the height of the eye from the surface of the earth, and the terms "circle "," circle & projections are used interchangeably to denote a circular pattern formed on the surface of the eye. When referring to a projected laser signal pointing to a specific point in the document or on the eye surface, it also includes a reflected signal that is reflected from the eye surface and returns to the laser range finder along a completely identical path, Is omitted.

The snowfall measuring system according to an embodiment of the present invention shown in FIG. 1 has three modules as follows: a laser distance measuring instrument 10, a step motor 11, and a controller 12.

1, the laser beam 16 projected by the laser distance measurer 10 attached to the step motor 11 is moved by the laser distance meter 10 to the step motor 11 at an angle (Or circular) 14 on the eye surface 15 as the laser distance measuring instrument 10 is rotated by the stepping motor 11. As a result, For the snowfall measurement, the laser range finder 10 sends a laser signal to a target point on the eye surface, receives a signal reflected on the eye surface, and calculates the distance to the point on the eye surface 15 to which the laser beam points . The distance data is transmitted to the control unit 12 and / or the central server, and the control unit 12 processes and stores the data.

2 shows how the direction of the laser signal from the laser distance meter 10 changes as the stepper motor 11 rotates due to the inclination of the laser distance meter 10 on the motor shaft 13 . 2, the laser distance measuring instrument 10 is slightly inclined by an angle? With respect to the direction of the motor shaft 13. As shown in Fig. As the stepper motor 11 rotates about the axis 13, the laser beam 16 from the laser range finder 10 forms a circular shape. The radius of the circle is determined by the distance between the eye surface (or ground) and the laser range finder 10 and the angle [theta].

3 shows a single laser beam projected at the laser distance meter 10 at a given time t and reflected back to the laser distance meter 10 by the eye surface. As shown in Fig. 3, when the distance measured from the laser distance measuring instrument 10 to the surface of the eye at a certain measuring time t is Ls ( t ) and the distance from the laser distance measuring instrument 10 to the ground surface is Lg ( t ) , The depth d ( t ) of the eye at the time point t can be obtained by the following equation. Here, ( t ) is the angle at which the laser beam meets the ground surface at time t .

d (t) = ((Lg (t) - Ls (t)) x sin θ (t)

In order to measure the next point on the circle 14 on the eye surface shown in Fig. 4, the control unit 12 rotates the step motor by the angle?. Then, in order to complete the measurement on all points on the circle, the measurement system of the present invention measures t = n-1 from t = 0 until the total angle rotated by the step motor 11 becomes a desired angle close to 360 degrees Repeat the same steps up to, or complete the intended number of measurements for one round of measurement. For example, when the total rotation of one round is 330 degrees,? Represents 330 / n or? Xn = 330, where? Represents the amount of rotation between adjacent points. Fig. 4 shows how the measurement is performed with respect to tf in terms of rotation angles at all points from t = 0 to t = n-1.

The snow depth (snowfall) d ( t ) at each time t (rotation angle tφ) can be obtained as follows.

d ( t ) = ( Lg ( t ) - Ls ( t )) x sin ? ( t )

(from t = 0 to n-1, n = number of samples measured along a circle on the target surface area on the eye)

Time t = 0 t = n-1 ( in the rotation angle tφ = 0 degree (n-1) φ degrees) from the measured Lg (t) and, θ (t) values at each time point to the calibration process (calibration procedure, which will be described later.

When the measurement of one rotation is completed, the controller 12 can store all measurement data in a local storage or transmit it to an external server for further analysis.

The control unit 12 and / or the external server analyzes the data by taking an average on the measured raw data. At this time, it is preferable to remove the abnormally high or low value from the measured data by comparing with the statistical value or the reference value. An example of a reference value is an average value of data measured at a neighboring point or an effective average value of snowfall previously measured at the same point. An exemplary graph measured for 24 points along a circle is shown in FIG. In this example, the spike (18, 19) and dip (20) can be removed when calculating the final result. Significant average data can be obtained by averaging the remaining values after significantly removing the abnormal values.

The measurement system of the present invention should be calibrated through the following procedure before it is first installed in the field and measurement is performed. 6 is a diagram showing a calibration method of the present invention at a specific time t . For calibration, a jig 21 in the form of a box or raised plane can be used to provide a predetermined eye depth (height) as shown in Fig.

7 is a flow chart showing an exemplary calibration procedure. Let Lg ( t ) be the distance from the laser range finder 10 to the surface at time t , and let Lr ( t ) be the distance to the surface of the jig. The first step in the calibration process is to measure the distance from the laser range finder 10 to the surface of the earth.

t = after a reset to zero, that is, by rotation by a step motor 11, the later placed at the initial position (step S70), clearing the surface (S71), measuring a Lg (t) and the step motor 11 φ t (Step S72). It is repeated until the step S72 to t = n (Step S73) and t = 0 measured Lg (t) at t = n-1, and to record.

Next, the same procedure is repeated (steps S75 and 76) by placing a jig 21 of Lref height on the ground surface (raising the target plane by Lref) (step S74). In other words, measure and record the Lr (t) at t = 0 to t = n-1 φ while rotated by a step motor (11).

Lref / (Lg (t) corresponding to Lg (t) and Lr for after measuring the (t) from t = 0 to t = n-1 sin θ (t) at each time t - Lr (t) (Step S77). These calculated coefficients (sin θ ( t ) from t = 0 to t = n-1) are used to calculate the snowfall d ( t ) using the measured Ls ( t ). The larger the Lref (the closer the plane (21) is to the laser range finder), the smaller the error and the closer the coefficient value is to the actual value.

The above two steps can be carried out sequentially, but it is also possible to proceed separately at different points as needed.

8 shows a measuring device according to an embodiment of the present invention surrounded by a protective housing 22. Fig. The hood may be provided in front of the laser range finder of the protective housing 22 to prevent the laser range finder 10 from diffusing light. Further, the protective housing 22 may be fixed to a column or a structure to prevent it from shaking or moving due to strong wind or other external force. The control unit 12 may be connected to an external communication module for communicating with a remote server where additional data processing is performed.

Since the laser range finder 10 has circuitry, a power supply is required for operation. Therefore, any form of connection means 28 is required between the control unit 12 and the laser range finder 10, as shown in Fig. The rotary connector may be used to maintain the connection even when the step motor 11 rotates the laser distance measuring instrument 10. [ The rotary connector takes up considerable space and increases the overall cost of the system. Also, it may not be a reliable way to supply signals and power for long periods of time in extreme weather conditions.

In the present invention, as shown in FIG. 9, a highly flexible cable is used as the connecting means 28 for connecting the control unit 12 and the laser distance measuring instrument 10. If a cable is used to connect the laser range finder 10 and the control unit 12, if the step motor 11 rotates only in one direction, the cable will be twisted and damaged and eventually stop operating. In a preferred embodiment, the stepper motor 11 rotates only in one direction and reverses its direction before reaching the end of the 360 degree circle. For example, if you measure at 30-degree intervals, measure up to 330 degrees and reverse the direction. This corresponds to a measurement of 360 degrees even if measured up to 330 degrees. When measuring at 50 degree intervals, measure up to 350 degrees and reverse direction.

If it works perfectly, it will be able to operate without damaging the cable and malfunctioning the system. However, there is an abnormal situation such as a system restart. Depending on the time at which the system is reset, the current position of the stepper motor 11 may not be the position that this method estimates when it begins a round of measurements. Therefore, there is always a possibility of malfunction that can cause cable damage.

In order to prevent this type of problem, in the present invention, mechanical stoppers 25 and 26 are used to stop the step motor 11 from suddenly turning over a limit. 9 and 10, when the step motor 11 rotates the laser range finder 10 over a predetermined angle, the mechanical structure 25 is blocked by the other structure 26 attached to the motor bracket . 9 and 10 show the mechanical structures of the stoppers attached to the laser range finder 10, the bracket 24, the step motor 11 and the controller 12 at different points in time.

This stopper mechanism can be used to relocate the stepping motor 11. However, it is not always possible to predict the exact position of the stepping motor 11 when two stoppers are struck due to uneven repulsion generated when the stepping motor 11 strikes the stopper. Also, from time to time, the stepper motor 11 may lose current position data for various reasons. Particularly, when the system is restarted, the probability of resetting the step motor 11 to exactly the same position is lowered.

To achieve the intended accuracy and sensitivity in the present invention, the system of the present invention measures the distance to target points while rotating the laser range finder in one direction only (e.g., direction A in FIG. 10).

For more precise repositioning of the step motor 11 and the laser range finder 10, an embodiment of the present invention uses a pair of infrared emitters and photodetectors such as phototransistors. The detection of the position of the laser range finder 10 using an infrared generator / phototransistor pair can be implemented in various ways. For example, a plastic switch or a piece of metal that passes through the photo switch can be used when attached to the laser distance meter 10 and reaches a specific position while rotating. Alternatively, a phototransistor / detector may be provided on the side or the bottom, and light reflected from a mark attached to the laser range finder 10 may be detected.

In an embodiment of the present invention, a positioning mechanism based on an infrared or visible light emitting device 29 and an infrared / phototransistor 31 is used. In this embodiment, an infrared or visible light signal 32 passes through the motor bracket 24 and the hole 30 in the motor housing, as shown in Fig.

Fig. 11 shows an embodiment of an optical sensing mechanism according to an embodiment of the present invention that allows a new measurement round to be initiated at exactly the same position. The infrared (or visible) light emitting element 29 emits an infrared (visible light) signal while the stepper motor 11 rotates the laser distance meter 10 and the infrared (visible light) The intensity of the signal 31 received through the drive 30 is checked. The bracket 24 rotates together with the rotation of the step motor 11. When the direction of the infrared signal emitted from the light emitting element 29 is perfectly aligned with the hole 30 formed in the bracket 24, The intensity of the magnetic field becomes maximum. In this embodiment, a long elongated hole is used so that the signal reaches only when the infrared (visible light) signal is perfectly aligned with the direction of the hole, as shown in Fig. 11, the step motor 11 is on the optical path and the step motor 11 is also provided with a hole. However, according to the embodiment, the step motor 11 is small in size so as to deviate from the optical path And the bracket 24 may be formed to have a U-shaped cross section in FIG. 11 so that a long and narrow hole is formed only in the bracket 24.

12 is a flow chart showing a preferred embodiment for implementing a position reset method for resetting (resetting) the stepper motor before starting a new measurement round. 13 is a diagram showing how a position reset algorithm uses positions following a single rotation of the stepper motor 11. In Fig.

Assume that direction A is positive. And assumes a zero point when the stopper hits when rotating in the opposite direction. Each measurement round begins at a start point 34 and ends at an end point 35 near the 360 degree circle just before striking the stopper again. In one embodiment, the measurement round uses only about 90% of the 360 degree circle.

The location reset process begins after completing one measurement round. Assuming that the step motor 11 is at the end point 35 after the immediately preceding measurement round, as shown in Fig. 12, when the process starts, it is necessary to hit the stopper (close to the position 36 in Fig. 13) The stepping motor 11 is slightly advanced (S120). The stepping motor 11 is rotated around the starting point 33 and the stepping motor 11 is rotated (S121), and then the stepping motor 11 is rotated so as to be positioned at the scanning start point 37 in the shade area between 37 and 38 S122). Then, the step motor 11 is moved by one step (or a predetermined number of microsteps), and the area indicated by shades 37 and 38 is scanned, the received infrared signal is read, and the position of the maximum value is recorded (S123) . This process is repeated for 2N points (S124). If the point 39 having the maximum intensity of the received infrared signal is determined, this point is set as the hole point (S125). Then, the control unit 30 moves backward by a predetermined number of points from the point 39 to reset the step motor 11 to the desired actual starting point 34 (S126).

When the system is restarted or powered up, the stepper motor 11 may not be at the endpoint 35 assumed by the algorithm, and when this occurs, the algorithm described above finds the position with the strongest signal from the beginning Maybe not. In this case, the step motor 11 is further moved backward by the step motor 11 so as to collide with the stopper 33, and the scanning of the maximum light intensity point 39 is started as described above do.

If the maximum point 39 is not found by any method, the stepper motor 11 is reset using the stopper mechanism. Basically, by stepping the stepper motor 11 vigorously against the stopper, it is ensured that the motor position is at the zero point 33. Then, the stepper motor 11 is moved by a few microsteps to the start point 34 estimated after the stopper is hit. Due to the bouncing back of the stepper motor 11 after being struck by the stopper, this mechanism can generate an offset and produce a slightly erroneous output. If the position setting mode is changed, it is necessary to calibrate again for precise measurement.

However, the shape of the circle is not important in the present invention, and it may be a complete circle or an ellipse according to the place where the apparatus is installed and the angle at which the laser signal is projected.

In the above description, the embodiment in which the control unit 12 and the laser range finder 10 are connected by using a cable has been described, but it is also possible to replace it with a radio. That is, instead of using a cable connecting the laser distance measuring device and the control unit, a wireless power transmitting unit is provided in the control unit 12, a wireless power receiving unit is provided in the laser distance measuring unit 10, 10, and a control unit 12 and a laser distance measuring unit 10 are provided with wireless data communication units, respectively, so that data can be wirelessly transmitted and received.

An example of this is shown in Fig. 14, a transmission coil 41 connected to a general transmission circuit 42 through a cable 45 and driven by a transmission circuit 42, and a transmission coil 41 disposed adjacent to the transmission coil 41 And power supply is wirelessly supplied to the laser distance measurer 10 by electromagnetic induction with the power reception coil 40 connected to the power reception circuit 44.

Data communication between the laser range finder 10 and the control unit 12 may be realized by providing near-field wireless data communication units 43 and 44 such as a Zigbee or Bluetooth module on both sides to transmit and receive data wirelessly. The power transmission circuit 42 and the power reception circuit 44 can be implemented using a general wireless power transmission / reception circuit. For example, the power transmission circuit 42 may be constituted by an oscillation circuit and a drive circuit, and the power reception circuit 44 may be constituted by a reception circuit and a rectification and a constant voltage circuit.

By configuring the controller 12 and the laser range finder 10 wirelessly, it is possible to avoid a complicated mechanism of using the cable, and the rotational direction of the laser range finder 10 can be continuously rotated in one direction And it is possible to maximize the number of measurement points by scanning the entire circumference of the rotating circumference and reduce the possibility of malfunction due to wear of the cable or the like.

The short-range wireless data communication units 43 and 44 may be configured to include a digital / analog port to directly transmit necessary control signals to both sides, and a separate processor may be added to perform data communication between the two sides and necessary control As shown in Fig.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program can be stored in a computer-readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention.

It is to be understood that the terms "comprises", "comprising", or "having" as used in the foregoing description mean that a component can be implanted unless specifically stated to the contrary, But should be construed as further including other elements.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10 laser distance meter,
11 step motor,
12 control unit,
21 Jig,
22 Housing,
24 bracket.

Claims (15)

A step motor including a rotating shaft,
A laser distance meter that is tilted at a predetermined angle and connected to the plane of the step motor and rotated,
Photodetector,
A cover provided at a position where light can be detected or blocked by the photodetector when the laser distance meter reaches a specific position while rotating,
A controller for controlling the stepping motor to control the laser distance measuring unit while rotating the laser distance measuring unit to measure distances at a plurality of target positions and to detect the position of the laser distance measuring unit using the light sensor and the mark,
And a snow cover. The method according to claim 1,
Wherein the controller measures the distance by controlling the laser distance meter, repeats the step of rotating the stepper motor by a predetermined rotation angle ϕ and then measuring the distance until the laser distance measurer substantially rotates once, And calculates a snowfall amount from the measured distance data. 3. The method of claim 2,
Ls the measurement distance to the surface of the eye from the laser range finder at any measured time point t (t), the angular distance Lg (t), to see the laser beam and the ground surface to the surface from the laser rangefinder θ (t ), The snowfall amount d ( t ) at the measurement order t is
d (t) = ((Lg (t) - Ls (t)) x sin θ (t)
Of the snowfall amount measuring device. The method of claim 3,
The control unit calculates an average snowfall amount using only the remaining measured values by removing a value higher or lower than a predetermined rate,
Wherein the reference value is a final average value of a snowfall amount measured during at least one immediately preceding rotation. 5. The method according to any one of claims 1 to 4,
The snowfall measuring device is housed in a protective housing for protecting the apparatus,
Wherein a hood is provided in front of the laser range finder of the protective housing. 5. The method according to any one of claims 1 to 4,
The laser range finder is connected by a power supply and a high expansion cable,
Wherein the control unit rotates the step motor in one direction and reverses the direction before reaching the end of the 360 degree circle. The method according to claim 6,
Further comprising a mechanical stopper for stopping the step motor from rotating beyond the limit. delete The method according to claim 1,
Wherein the indicator is a light generator. 10. The method of claim 9,
Further comprising a bracket positioned between the photodetector and the light generator and rotating together with the rotation of the stepping motor,
Characterized in that the bracket is provided with a hole which is formed in a position such that the direction of the optical signal emitted from the light generator is perfectly aligned with the hole when the stepper motor is in a predetermined position Measuring device. 11. The method of claim 10,
Wherein said hole has an elongated shape. The method according to claim 1,
The photodetector is a photo switch,
Wherein the mark is an object that is attached to the laser distance measuring device and blocks light between the light generator and the photodetector of the photo switch while passing through the photo switch when the light reaches a specific position while rotating. 8. The method of claim 7,
The control unit rotates the step motor so as to be positioned at the scan start point after the immediately preceding measurement round, and then moves the step motor by one step to read the received infrared signal to determine the position of the maximum value, So as to reset the position of the step motor. 14. The method of claim 13,
Wherein the control unit further moves the step motor so as to collide with the stopper immediately after the immediately preceding measurement round, and then rotates the step motor so as to be located at the scan start point. 5. The method according to any one of claims 1 to 4,
The control unit includes a wireless power transmission unit for wirelessly transmitting power and a data wireless communication unit for wirelessly transmitting and receiving data, and the laser range finder includes a wireless power receiver for wirelessly receiving power, And a data wireless communication unit for transmitting and receiving data.

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