WO2020045445A1

WO2020045445A1 - Distance measuring device, distance measuring device group, and distance measuring device system

Info

Publication number: WO2020045445A1
Application number: PCT/JP2019/033542
Authority: WO
Inventors: 岡本　修治; 佐伯　哲夫; 石丸　裕; 和穂江川; 智浩江川; 裕多堀
Original assignee: 日本電産株式会社
Priority date: 2018-08-29
Filing date: 2019-08-27
Publication date: 2020-03-05

Abstract

The objective of the present invention is to provide a distance measuring device with which it is possible to suppress erroneous measurements of distance resulting from interference from other distance measuring devices. This distance measuring device is provided with a light projecting unit (83) which includes a light emitting unit (701) and which performs revolving scanning of emitted light, a light receiving unit (702) which outputs a light reception signal on the basis of light reception, and a distance measuring unit (703) which measures the distance to an object being measured (OJ) on the basis of the emission of the emitted light and the light reception by the light receiving unit (702), wherein, on the basis of an offset between the light reception timings of the light reception signals obtained when the light projecting unit (83) emits the emitted light in a plurality of scanning positions offset by a prescribed angle of rotation in the same revolution, the distance measuring unit (703) determines that the light reception signals are based on light reflected by the object being measured (OJ).

Description

Distance measuring device, distance measuring device group, and distance measuring device system

The present invention relates to a distance measuring device, a distance measuring device group, and a distance measuring device system.

Conventionally, various distance measuring devices have been developed. For example, Patent Literature 1 discloses an autonomous mobile device including a laser range finder.

In Patent Literature 1, a laser range finder scans a laser in a horizontal direction around an autonomous mobile device in a fan shape within a predetermined range. That is, the laser range finder emits the laser at every predetermined angle. Then, the laser range finder detects the laser reflected from the object and returns, and determines the angle between the laser and the object based on the emission angle of the laser and the time from when the laser is emitted to when the laser reflects and returns from the object. And distance.

The autonomous mobile device has a local map creating unit and a self-position estimating unit. The local map creator creates a local map around the own device with the laser range finder as the origin, based on information detected by the laser range finder. The self-position estimating unit compares the local map, which has been transformed into the coordinate system (absolute coordinate system) of the environment map, with the environment map, and estimates the self-position based on the result of the comparison.

The autonomous mobile device has a sign detection unit. The sign detection unit detects a sign based on the output pattern of the detection information and the non-detection information output from the laser range finder. More specifically, the sign detection unit is configured such that a plurality of detection information groups and a plurality of non-detection information groups alternately appear a predetermined number of times, and the number of non-detection information included in each of the plurality of non-detection information groups Is within the first predetermined range and the number of pieces of detection information included in each of the plurality of detection information groups is within the second predetermined range, it is determined that the detection target is a marker. The self-position estimating unit corrects the estimated self-position based on the sign detected by the sign detecting unit.

Japanese Unexamined Patent Publication: JP-A-2014-6833

According to the autonomous mobile device of Patent Document 1 described above, it is possible to reliably determine and detect a sign, regardless of the environment in which the sign is placed, and to perform accurate autonomous movement. ing. Patent Document 1 also discloses that the sign detection unit determines that the detected object is a sign when the same detected object is determined to be a sign a plurality of times. It is stated that this makes it possible to more reliably prevent erroneous detection of a sign.

However, in a situation where a plurality of autonomous mobile devices equipped with a laser range finder are operated, for example, when a laser emitted from another laser range finder is directly or indirectly input to its own laser range finder, its own The laser range finder may measure the distance erroneously, but Patent Document 1 does not solve this problem.

In view of the above situation, an object of the present invention is to provide a distance measuring device capable of suppressing erroneous distance measurement due to interference from another distance measuring device.

An exemplary distance measuring device according to the present invention includes a light emitting unit that includes a light emitting unit and performs rotational scanning of emitted light, a light receiving unit that outputs a light receiving signal based on light reception, an emission of the emitted light, and the light receiving unit. And a distance measuring unit that measures a distance to a measurement target based on light reception by the light emitting unit. It is determined that the light receiving signal is based on the light reflected by the object to be measured, based on the shift of the light receiving timing of the light receiving signal obtained when the light is emitted.

According to the exemplary distance measuring device of the present invention, it is possible to suppress erroneous distance measurement due to interference from another distance measuring device.

FIG. 1 is a schematic overall perspective view of an automatic guided vehicle according to one embodiment of the present invention. FIG. 2 is a schematic side view of the automatic guided vehicle according to one embodiment of the present invention. FIG. 3 is a plan view of the automatic guided vehicle according to one embodiment of the present invention as viewed from above. FIG. 4 is a schematic side sectional view of the distance measuring device according to one embodiment of the present invention. FIG. 5 is a block diagram showing an electrical configuration of the distance measuring device according to one embodiment of the present invention. FIG. 6 is a block diagram showing an electrical configuration of the automatic guided vehicle according to one embodiment of the present invention. FIG. 7 is a block diagram illustrating a first configuration example of the distance measurement unit. FIG. 8 is a diagram for explaining pulse width correction. FIG. 9 is a diagram illustrating a situation where a plurality of automatic guided vehicles equipped with a distance measuring device operate in a warehouse or the like. FIG. 10 is a diagram illustrating an example of a waveform of a light reception signal obtained when the emission light is emitted at the first scanning position. FIG. 11 is a diagram illustrating an example of a waveform of a received light signal obtained when the emitted light is emitted at the second scanning position. FIG. 12 is a diagram in which the waveforms shown in FIGS. 10 and 11 are overlapped. FIG. 13 is a diagram illustrating a situation where a plurality of automatic guided vehicles operate in a warehouse or the like and a situation where a worker works. FIG. 14 is a block diagram illustrating a second configuration example of the distance measurement unit. FIG. 15 is a flowchart of a process performed by the distance measurement unit of the second configuration example. FIG. 16 is a waveform diagram showing an example of the light receiving signal. FIG. 17 is a schematic diagram illustrating a configuration example of a distance measurement device system. FIG. 18 is a waveform diagram showing an example of each light receiving signal obtained at the first scanning position and the second scanning position in an overlapping manner.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. Here, an example in which the distance measuring device is configured as a laser range finder will be described. In addition, as an example of a moving body on which a distance measuring device is mounted, an automatic guided vehicle that is used to carry a load will be described as an example. The automatic guided vehicle is also generally called an AGV (Automatic Guided Vehicle).

<1. FIG. 1 is a schematic overall perspective view of an automatic guided vehicle 15 according to an embodiment of the present invention. FIG. 2 is a schematic side view of the automatic guided vehicle 15 according to one embodiment of the present invention. FIG. 3 is a plan view seen from above of the automatic guided vehicle 15 according to one embodiment of the present invention. The automatic guided vehicle 15 travels autonomously by two-wheel drive and transports luggage.

The automatic guided vehicle 15 includes the vehicle body 1, the carrier 2, the

support portions

3L and 3R, the

drive motors

4L and 4R, the

drive wheels

5L and 5R, the driven

wheels

6F and 6R, and the distance measuring device 7. .

The vehicle body 1 includes a base 1A and a base 1B. The plate-like base 1B is fixed to the rear upper surface of the base 1A. The base 1B has a triangular portion Tr protruding forward. The plate-shaped carrier 2 is fixed to the upper surface of the platform 1B. Luggage can be placed on the upper surface of the bed 2. The carrier 2 extends further forward than the platform 1B. Thereby, a gap S is formed between the front of the base 1A and the front of the carrier 2.

The distance measuring device 7 is disposed in the gap S at a position in front of the vertex of the triangular portion Tr of the base 1B. The distance measuring device 7 is configured as a laser range finder, and measures a distance to a measurement target while scanning a laser beam. The distance measurement device 7 is used for obstacle detection, map information creation, and self-position identification described later. The detailed configuration of the distance measuring device 7 itself will be described later.

The support 3L is fixed to the left side of the base 1A, and supports the drive motor 4L. The drive motor 4L is configured by, for example, an AC servomotor. The drive motor 4L incorporates a speed reducer (not shown). The drive wheel 5L is fixed to a rotating shaft of the drive motor 4L.

The support 3R is fixed to the right side of the base 1A and supports the drive motor 4R. The drive motor 4R is configured by, for example, an AC servomotor. The drive motor 4R incorporates a speed reducer (not shown). The drive wheel 5R is fixed to a rotating shaft of the drive motor 4R.

The driven wheel 6F is fixed to the front side of the base 1A. The driven wheel 6R is fixed to the rear side of the base 1A. The driven

wheels

6F, 6R rotate passively according to the rotation of the

drive wheels

5L, 5R.

By driving the

drive wheels

5L, 5R by the

drive motors

4L, 4R, the automatic guided vehicle 15 can be moved forward and backward. In addition, by controlling the rotational speeds of the

drive wheels

5L and 5R to provide a difference, the automatic guided vehicle 15 can be turned clockwise or counterclockwise to change the direction.

The base 1A houses therein a control unit U, a battery B, and a communication unit T. The control unit U is connected to the distance measuring device 7, the

drive motors

4L and 4R, the communication unit T, and the like.

The control unit U communicates various signals with the distance measuring device 7 as described later. The control unit U also controls the drive of the

drive motors

4L and 4R. The communication unit T communicates with an external tablet terminal (not shown) and conforms to, for example, Bluetooth (registered trademark). Thereby, the automatic guided vehicle 15 can be remotely controlled by the tablet terminal. The battery B is composed of, for example, a lithium ion battery, and supplies power to each unit such as the distance measuring device 7, the control unit U, and the communication unit T.

<2. Configuration of Distance Measuring Device> FIG. 4 is a schematic side sectional view of the distance measuring device 7. The distance measuring device 7 configured as a laser range finder includes a laser light source 71, a collimating lens 72, a light projecting mirror 73, a light receiving lens 74, a light receiving mirror 75, a wavelength filter 76, a light receiving element 77, A housing 78, a motor 79, a housing 80, a substrate 81, and a wiring 82 are provided.

The housing 80 has a substantially columnar shape extending in the vertical direction when viewed from the outside, and accommodates various components including the laser light source 71 in the internal space. The laser light source 71 is mounted on the lower surface of a substrate 81 fixed to the lower surface of the upper end of the housing 80. The laser light source 71 emits, for example, laser light in the infrared region downward.

The collimating lens 72 is disposed below the laser light source 71. The collimating lens 72 emits the laser light emitted from the laser light source 71 downward as parallel light. A light projecting mirror 73 is arranged below the collimating lens 72.

The light projecting mirror 73 is fixed to the rotating housing 78. The rotating housing 78 is fixed to a shaft 79 </ b> A of the motor 79, and is driven to rotate around the rotation axis J by the motor 79. With the rotation of the rotating housing 78, the light projecting mirror 73 is also driven to rotate about the rotation axis J. The light projecting mirror 73 reflects the laser light emitted from the collimating lens 72, and emits the reflected laser light as emission light L1. Since the light projecting mirror 73 is driven to rotate as described above, the emission light L1 is emitted while changing the emission direction within a range of 360 degrees around the rotation axis J.

The housing 80 has a transmission part 801 in the middle in the vertical direction. The transmissive portion 801 is made of a translucent resin or the like.

The outgoing light L1 reflected and emitted by the light projecting mirror 73 is transmitted through the transmitting portion 801 and passes through the gap S and is emitted outward from the automatic guided vehicle 15. In the present embodiment, the predetermined rotation scanning angle range θ is set to 270 degrees around the rotation axis J as an example, as shown in FIG. More specifically, the range of 270 degrees includes 180 degrees in the front and 45 degrees in the left and right directions. The emitted light L1 is transmitted through the transmission part 801 at least within a range of 270 degrees around the rotation axis J. In a range where the rear transmission part 801 is not disposed, the emitted light L1 is blocked by the inner wall of the housing 80, the wiring 82, or the like.

The light receiving mirror 75 is fixed to the rotating housing 78 at a position below the light projecting mirror 73. The light receiving lens 74 is fixed to a circumferential side surface of the rotating housing 78. The wavelength filter 76 is located below the light receiving mirror 75 and is fixed to the rotating housing 78. The light receiving element 77 is located below the wavelength filter 76 and is fixed to the rotating housing 78.

The outgoing light L1 emitted from the distance measuring device 7 is reflected by the object to be measured and becomes diffused light. Part of the diffused light is transmitted through the gap S and the transmission portion 801 as incident light L2 and is incident on the light receiving lens 74. The incident light L2 transmitted through the light receiving lens 74 is incident on the light receiving mirror 75, and is reflected downward by the light receiving mirror 75. The reflected incident light L2 passes through the wavelength filter 76 and is received by the light receiving element 77. The wavelength filter 76 transmits light in the infrared region. The light receiving element 77 converts the received light into an electric signal by photoelectric conversion.

When the rotating housing 78 is driven to rotate by the motor 79, the light receiving lens 74, the light receiving mirror 75, the wavelength filter 76, and the light receiving element 77 are driven to rotate together with the light projecting mirror 73.

As shown in FIG. 3, the measurement range Rs is defined as a range formed by rotating around the rotation axis J with a predetermined radius in the rotation scanning angle range θ (= 270 degrees). However, the predetermined radius changes according to the output level of the emitted light L1. When the outgoing light L1 is emitted in the rotational scanning angle range θ and the outgoing light L1 is reflected by the measurement object located within the measurement range Rs, the reflected light is transmitted through the transmission unit 801 as incident light L2 and is received by the light receiving lens 74. Is incident on.

The motor 79 is connected to the substrate 81 by a wiring 82 and is driven to rotate by being energized from the substrate 81. The motor 79 rotates the rotating housing 78 at a predetermined rotation speed. For example, the rotating housing 78 is driven to rotate at about 3000 rpm. The wiring 82 is routed vertically along the rear inner wall of the housing 80.

<3. Electrical Configuration of Distance Measuring Apparatus> Next, the electrical configuration of the distance measuring apparatus 7 will be described. FIG. 5 is a block diagram illustrating an electrical configuration of the distance measuring device 7.

As shown in FIG. 5, the distance measuring device 7 includes a laser light emitting unit 701, a laser light receiving unit 702, a distance measuring unit 703, a data communication interface 704, a second arithmetic processing unit 705, a driving unit 706, And a motor 79.

The laser light emitting unit 701 includes a laser light source 71 (FIG. 4), an LD driver (not shown) for driving the laser light source 71, and the like. The LD driver is mounted on the substrate 81. The laser emitting unit 701, the light projecting mirror 73, the rotating housing 78, and the motor 79 constitute a light emitting unit 83 (FIG. 4). That is, the distance measuring device 7 includes the light projecting unit 83 that includes the light emitting unit (laser light emitting unit 701) and performs rotational scanning of the emitted light L1.

Laser light receiving section 702 includes light receiving element 77 (FIG. 4) and the like, and outputs a light receiving signal based on the received light. That is, the distance measuring device 7 includes a light receiving unit (laser light receiving unit 702) that outputs a light receiving signal based on light reception. The more specific configuration of the laser light receiving unit 702 will be described later.

The distance measuring unit 703 receives a light receiving signal output from the laser light receiving unit 702. The distance measuring unit 703 has a first arithmetic processing unit 703A. The laser emission unit 701 emits a pulsed laser beam using the laser emission pulse LP output from the first arithmetic processing unit 703A as a trigger. At this time, the outgoing light L1 is emitted. When the emitted light L1 is reflected by the measurement object OJ, the incident light L2 is received by the laser light receiving unit 702. Laser light receiving section 702 outputs a light receiving signal to distance measuring section 703 based on the reception of incident light L2.

Here, the first arithmetic processing unit 703A outputs a reference pulse (not shown in FIG. 5) output together with the laser emission pulse LP. The distance measurement unit 703 can acquire the distance to the measurement target OJ by measuring the elapsed time from the rising timing of the reference pulse to the rising timing of the light receiving signal. That is, the distance measuring unit 703 measures the distance by a so-called TOF (Time @ Of @ Flight) method. As described above, the distance measuring device 7 includes the distance measuring unit 703 that measures the distance to the measurement target OJ based on the emission of the emitted light and the light reception by the light receiving unit 702. The more specific configuration of the distance measuring device 7 will be described later.

The drive unit 706 controls the rotation of the motor 79. The motor 79 is driven to rotate at a predetermined rotation speed by the drive unit 706. The first arithmetic processing unit 703A outputs a laser emission pulse LP each time the motor 79 rotates by a predetermined unit angle. As a result, each time the rotating housing 78 and the light projecting mirror 73 rotate by a predetermined angle, the laser light emitting unit 701 emits light, and the emitted light L1 is emitted. FIG. 3 shows that the emitted light L1 is emitted at every predetermined rotation angle Δθ.

The first arithmetic processing unit 703A uses the distance measurement device 7 as a reference based on the rotation angle position of the motor 79 at the timing when the laser emission pulse LP is output and the distance measurement data obtained corresponding to the laser emission pulse LP. To generate position information on the orthogonal coordinate system. That is, the position of the measurement object OJ is acquired based on the rotation angle position of the light projecting mirror 73 and the measured distance. The acquired position information is output from the first arithmetic processing unit 703A as measured distance data DT. In this manner, a distance image of the measurement object OJ can be obtained by rotational scanning of the emitted light L1 in the rotational scanning angle range θ.

The measured distance data DT output from the first arithmetic processing unit 703A is transmitted via the data communication interface 704 to the automatic guided vehicle 15 shown in FIG.

The second arithmetic processing unit 705 determines whether or not the measurement target is located within a predetermined area based on the measurement distance data DT. Specifically, if the position of a certain measurement target indicated by the measurement distance data DT is located within the predetermined area, it is determined that the measurement target is located within the predetermined area. When determining that the measurement target is located within the predetermined area, the second arithmetic processing unit 705 outputs the detection signal Ds, which is a flag, as a High level. On the other hand, when the measurement object is not located within the predetermined area, the detection signal Ds having a low level is output. The detection signal Ds is transmitted to the automatic guided vehicle 15 shown in FIG.

<4. Electric Configuration of Automated Carrier> As described above, the electric configuration of the distance measurement device 7 has been described. Here, the electrical configuration of the automatic guided vehicle 15 will be described with reference to FIG. FIG. 6 is a block diagram illustrating an electrical configuration of the automatic guided vehicle 15.

As shown in FIG. 6, the automatic guided vehicle 15 includes a distance measuring device 7, a control unit 8, a driving unit 9, and a communication unit T.

The control unit 8 is provided in the control unit U (FIG. 1). The control unit 8 is configured by a processor such as a CPU (Central Processing Unit). The drive unit 9 includes a motor driver (not shown) and drive

motors

4L and 4R. The motor driver is provided in the control unit U. The control unit 8 issues a command to the drive unit 9 and controls the drive unit 9. The driving unit 9 controls the driving speed and the rotating direction of the

driving wheels

5L and 5R.

The control unit 8 communicates with a tablet terminal (not shown) via the communication unit T. For example, the control unit 8 can receive, via the communication unit T, an operation signal corresponding to the content operated on the tablet terminal.

The measured distance data DT output from the distance measuring device 7 is input to the control unit 8. The control unit 8 can create map information based on the measured distance data DT. The map information is information generated for performing self-position identification for specifying the position of the automatic guided vehicle 15 and is generated as position information of a stationary object at a place where the automatic guided vehicle 15 runs. For example, when the location where the automatic guided vehicle 15 travels is a warehouse, the stationary object is a wall of the warehouse, shelves arranged in the warehouse, or the like.

The map information is generated, for example, when a manual operation of the automatic guided vehicle 15 is performed by the tablet terminal. In this case, an operation signal corresponding to the operation of, for example, the joystick of the tablet terminal is transmitted to the control unit 8 via the communication unit T, and the control unit 8 instructs the driving unit 9 in accordance with the operation signal, The traveling control of the transport vehicle 15 is performed. At this time, based on the measured distance data DT input from the distance measuring device 7 and the position of the automatic guided vehicle 15, the control unit 8 specifies the position of the measurement target at the place where the automatic guided vehicle 15 travels as map information. I do. The position of the automatic guided vehicle 15 is specified based on the drive information of the drive unit 9.

The map information generated as described above is stored in the storage unit 85 of the control unit 8. The control unit 8 compares the measured distance data DT input from the distance measuring device 7 with the map information stored in advance in the storage unit 85, thereby identifying the position of the automatic guided vehicle 15 itself. I do. That is, the control unit 8 functions as a position identification unit. By performing the self-position identification, the control unit 8 can perform autonomous traveling control of the automatic guided vehicle 15 along a predetermined route.

The control unit 8 can also control the driving unit 9 based on the detection signal Ds output from the distance measuring device 7.

<5. First Configuration Example of Distance Measurement Unit> FIG. 7 is a block diagram illustrating a first configuration example of the distance measurement unit 703. FIG. 7 also shows a specific configuration example of the laser light receiving unit 702.

The laser light receiving section 702 has an APD (avalanche photodiode) 702A and an amplifier circuit (transimpedance amplifier) 702B. The APD 702A corresponds to the light receiving element 77, and converts the received laser light into a current signal. The amplifier circuit 702B converts the current signal output from the APD 702A into a light receiving signal Ps by current / voltage conversion and outputs the light receiving signal Ps.

The distance measuring unit 703 includes a first TDC (time to digital converter) 703B and a second TDC 703C in addition to the above-described first arithmetic processing unit 703A. The first TDC 703B measures an elapsed time T1 from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A to the rising timing of the light receiving signal Ps output from the amplifier circuit 702B. The second TDC 703C measures an elapsed time T2 from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A to the falling timing of the light receiving signal Ps output from the amplifier circuit 702B.

The first arithmetic processing unit 703A performs the following distance measurement by pulse width correction based on the measurement results by the first TDC 703B and the second TDC 703C. The light receiving signal Ps is not actually a pulse waveform but a waveform having a gradient with respect to time, as shown in FIG. Accordingly, even if the elapsed time T1 from the rising timing t0 of the reference pulse SP to the timing of crossing the first light receiving threshold Th1 when the light receiving signal Ps rises is measured by the first TDC 703B, it is necessary to measure the elapsed time for accurate distance measurement. It is necessary to perform the correction by subtracting the correction amount Δt from the time T1. The correction amount Δt is a time from when the light receiving signal Ps rises to the first light receiving threshold Th1 from the zero level.

Therefore, in the pulse width correction, the elapsed time T2 from the rising timing t0 of the reference pulse SP to the timing of crossing the second light receiving threshold Th2 when the light receiving signal Ps falls is also measured by the second TDC 703C, and the elapsed times T2 and T1 are measured. Is calculated as the pulse width W. As the peak level of the light receiving signal Ps increases, the rising and falling of the light receiving signal become steeper, the pulse width W increases, and the correction amount Δt decreases. Therefore, the correction amount Δt is determined based on the actually calculated pulse width W and the relationship between the preset pulse width W and the correction amount Δt. Then, distance measurement is performed by subtracting the determined correction amount Δt from the measured elapsed time T1.

<6. Interference Influence Suppression Function> Here, as shown in FIG. 9, in a warehouse or the like, in addition to the automatic guided vehicle 15 equipped with the distance measuring device 7, another automatic guided vehicle 150 equipped with the distance measuring device 70 operates. Suppose you have a situation. In this case, there is a possibility that the laser light emitted from another distance measuring device 70 is directly input to the distance measuring device 7 as direct light DL. Alternatively, there is a possibility that the laser light emitted from another distance measuring device 70 is reflected by an object such as a wall of a warehouse and is indirectly input to the distance measuring device 7 as reflected light RL.

If the distance measuring device 7 measures the distance based on the reception of the direct light DL or the reflected light RL, there is a possibility that the distance measuring device 7 erroneously measures a distance different from the distance to the measurement target to be measured. In addition to the situation shown in FIG. 9, for example, when another fixed type distance measuring device (for preventing intrusion, etc.) is present, the effect of the laser beam emitted from the distance measuring device is the same. .

Thus, the distance measuring device 7 of the present embodiment has a function of suppressing the influence of such interference from other distance measuring devices. Hereinafter, such a function will be described with reference to FIGS. 10 to 12 as an example.

FIG. 10 shows an example of the waveform of the light receiving signal Ps1 obtained when the emission light L1 is emitted at a certain first scanning position in the measurement range Rs (FIG. 3) for scanning the emission light L1. The scanning position is an angular position around the rotation axis J with reference to a predetermined radial direction about the rotation axis J with reference to FIG. The light receiving signal Ps1 shown in FIG. 10 is shown as a waveform with respect to the timing at which the emission light L1 is emitted, that is, the elapsed time from the rising timing of the reference pulse SP. This is the same in FIGS. 11 and 12. As shown in FIG. 10, the received light signal Ps1 includes a received light signal Ps11 based on the reception of the reflected light of the outgoing light L1 reflected by the measurement target, and a received light signal Ps1 based on the reception of the direct light emitted from another distance measuring device. Ps12.

FIG. 11 shows an example of the waveform of the light receiving signal Ps2 obtained when the emitted light L1 is emitted at the second scanning position shifted from the first scanning position by the predetermined rotation angle Δθ (FIG. 3) in the same revolution. As shown in FIG. 11, the received light signal Ps2 is composed of a received light signal Ps21 based on the reception of the reflected light reflected from the object to be emitted and the received light signal Ps2 based on the reception of the direct light emitted from another distance measuring device. Ps22.

When emitting the emitted light L1 at the first scanning position, the distance measuring unit 703 uses the first TDC 703B to start from the rising timing of the reference pulse PS to the timing of crossing the first light receiving threshold Th1 at the rising of each of the light receiving signals Ps11 and Ps12. The elapsed times T10 and T11 are measured. Further, when the emission light L1 is emitted at the first scanning position, the distance measurement unit 703 uses the second TDC 703C to determine the second light reception threshold Th2 at the fall of each of the light reception signals Ps11 and Ps12 from the rise timing of the reference pulse PS. The elapsed times T20 and T21 until the crossing timing are measured.

Further, when the emission light L1 is emitted at the second scanning position, the distance measurement unit 703 uses the first TDC 703B to cross the first light reception threshold Th1 at the rise of each of the light reception signals Ps21 and PS22 from the rise timing of the reference pulse PS. The elapsed times T12 and T13 until the timing are measured. Further, when the emission light L1 is emitted at the second scanning position, the distance measurement unit 703 uses the second TDC 703C to determine the second light reception threshold value Th2 at the fall of each of the light reception signals Ps21 and PS22 from the rise timing of the reference pulse PS. The elapsed times T22 and T23 until the crossing timing are measured.

Then, the first arithmetic processing unit 703A included in the distance measuring unit 703 calculates the difference between the elapsed times until the light reception signals obtained at the first and second scanning positions cross the first light reception threshold Th1 by a predetermined time difference. It is determined whether it is within. That is, in the example of FIGS. 10 and 11, the first arithmetic processing unit 703A compares the difference between the elapsed times T10 and T12 and the difference between the elapsed times T11 and T13 with the predetermined time differences.

Here, FIG. 12 is a diagram in which the waveforms shown in FIGS. 10 and 11 are overlapped. As described above, since the light receiving signals Ps11 and PS21 are light receiving signals based on the reception of the reflected light of the outgoing light L1 by the measurement object, there is almost no difference between the elapsed times T10 and T12, and the difference is within a predetermined time difference. Becomes

On the other hand, since the light receiving signals Ps12 and Ps22 are light receiving signals based on the reception of the direct light emitted from the other distance measuring devices, the difference ΔT between the elapsed times T11 and T13 increases, and the difference ΔT is within a predetermined time difference. No longer. Other distance measuring devices often have different rotational speeds for the rotation scanning of the emitted light from their own distance measuring device 7, in which case the deviation of the light receiving timing of the direct light in the distance measuring device 7 becomes large, and the difference ΔT Becomes larger. Even if the rotation speed is the same in setting, the rotation speed is often shifted due to an error in many cases. In this case, the shift of the light receiving timing of the direct light also becomes large. The same applies to the case where the light emitted from another distance measuring device receives the reflected light (reflected light RL in FIG. 9) reflected by the object.

Therefore, the first arithmetic processing unit 703A determines that the received light signal is based on the light reflected by the measurement object when the difference between the elapsed times is within the predetermined time difference, and otherwise, the received light signal is another signal. It is determined that it is based on the light emitted from the distance measuring device.

Therefore, when the difference between the elapsed times is within the predetermined time difference, the first arithmetic processing unit 703A determines whether the elapsed time until the light reception signal crosses the first light reception threshold Th1 and the time until the second light reception threshold Th2 crosses. Based on the elapsed time, distance measurement is performed using the pulse width correction described above. For example, in the case of FIGS. 10 and 11, the pulse width correction is performed based on the elapsed times T10 and T20 or the elapsed times T12 and T22.

On the other hand, when the difference between the elapsed times is not within the predetermined time difference, the first arithmetic processing unit 703A does not perform the distance measurement. That is, in the examples of FIGS. 10 and 11, distance measurement is not performed on the light receiving signals Ps12 and Ps22. Thereby, it is possible to suppress the distance from being erroneously measured due to interference by the light emitted from another distance measuring device.

That is, the distance measuring unit 703 determines the light receiving signal based on the shift of the light receiving timing of the light receiving signal obtained when the light projecting unit 83 emits the emitted light L1 at a plurality of scanning positions shifted by the predetermined rotation angle Δθ in the same revolution. It is determined that it is based on the light reflected by the measurement object. Thereby, whether the received light signal is based on the light reflected from the object to be measured or the light emitted from another distance measuring device is determined, so that the light receiving signal is determined based on the light emitted from the other distance measuring device. Erroneous measurement of the distance can be suppressed.

More specifically, the distance measurement unit 703 determines that the light reception signal is based on the light reflected by the measurement target when the evaluation value based on the shift in the light reception timing is within a predetermined time difference.

The first arithmetic processing unit 703A determines whether the difference between the elapsed times until the light reception signals obtained at the first and second scanning positions cross the second light reception threshold Th2 is within a predetermined time difference. You may.

Further, the second scanning position is not limited to a position shifted from the first scanning position by a predetermined rotation angle Δθ which is an interval for emitting the emission light L1, but is shifted from the first scanning position by twice the predetermined rotation angle Δθ, for example. Or the like.

<7. Setting of predetermined time difference> 差 The predetermined time difference to be compared with the above-described shift of the light receiving timing can be set based on, for example, the following calculation formula.

That is, the predetermined time difference is defined based on the following equation (1). ΔTth = (((V1 + V2 ) × Δtθ + L err × 2) × 2) / c (1) where,? Tth: predetermined time difference, V1: the distance the moving speed of the moving body measuring device is mounted, V2: a predetermined value, Δtθ: Measurement time interval corresponding to a predetermined rotation angle, L _err : maximum error of distance measurement, c: speed of light

V1 is the moving speed of the moving object (automated guided vehicle 15) on which the distance measuring device 7 is mounted. V2 is, for example, the moving speed of another automatic guided vehicle 150 shown in FIG. In the above formula (1), it is assumed that the automatic guided vehicle 15 and the other automatic guided vehicle 150 approach or separate from each other. Thereby, when the distance measuring device 7 receives the reflected light RL150 (FIG. 13) reflected by the automatic guided vehicle 150 from the output light L1 emitted from the distance measuring device 7, the distance measuring device 150 recognizes the automatic guided vehicle 150 as the measurement target. can do. When the worker 200 working in the warehouse shown in FIG. 13 moves at a moving speed of V2 or less, for example, the distance measuring device 7 reflects the emitted light L1 emitted from the distance measuring device 7 by the worker 200. When the reflected light RL200 (FIG. 13) is received, the worker 200 can be recognized as a measurement target.

To explain with a specific example, for example, the rotational speed of the rotational scanning in the distance measuring device 7 = 2400 rpm, the predetermined rotation angle Δθ = 0.125 °, the maximum distance measurement error of the distance measuring device 7 = ± 30 mm, the self-unmanned conveyance It is assumed that the moving speed V1 of the vehicle 15 is 10 km / h and the moving speed V2 of the other automatic guided vehicle 150 is 10 km / h. At this time, the measurement time interval Δtθ corresponding to the predetermined rotation angle Δθ is 8.68 μs.

In this case, (V1 + V2) × Δtθ = (10 × 10 ⁶ /3600)×2×8.68×10 ⁻⁶ = 0.048 mm in the above equation (1).

Therefore, from the above equation (1), the predetermined time difference ΔTth = ((0.048 + 30 × 2) × 2) / (2.9997 × 10 ¹¹ ) = 0.4006 ns.

Therefore, if the shift of the light receiving timing is within 0.4006 ns, it is determined that the light receiving signal is based on the reflected light reflected by the measurement object, the emitted light L1 emitted from the distance measuring device 7.

As described above, according to the above equation (1), the moving speed of the moving object (the unmanned transport vehicle 15) on which the distance measuring device 7 is mounted and the moving speed (V2) of the other moving objects (the unmanned transport vehicle 150 and the like). The predetermined time difference can be appropriately defined in consideration of the distance measurement maximum error and the distance measurement maximum error.

<8. Second Configuration Example of Distance Measurement Unit> FIG. 14 is a block diagram showing a second configuration example of the distance measurement unit 703. The distance measuring unit 703 of this configuration example further includes a first comparator 703D and a second comparator 703E as a configuration difference from the first configuration example (FIG. 7).

The first comparator 703D compares the light receiving signal Ps input to the non-inverting input terminal (+) with the first threshold value Vth1 input to the inverting input terminal (-), and compares the comparison result with the first operation processing unit. 703A. The second comparator 703E compares the light receiving signal Ps input to the inverting input terminal (−) with the second threshold value Vth2 input to the non-inverting input terminal (+), and compares the comparison result with the first arithmetic processing unit. 703A. The second threshold value Vth2 is smaller than the first threshold value Vth1.

The distance measuring unit 703 of the second configuration example performs the processing shown in the flowchart of FIG. First, in step S1, the first arithmetic processing unit 703A determines whether the intensity of the light receiving signal Ps is equal to or greater than the first threshold value Vth1 based on the output level of the first comparator 703D. That is, if the output level of the first comparator 703D is High, the intensity of the light receiving signal Ps is equal to or higher than the first threshold Vth1, and if the output level is Low, the intensity of the light receiving signal Ps is lower than the first threshold Vth1.

If the intensity of the light receiving signal Ps is equal to or greater than the first threshold value Vth1 (Y in step S1), the light receiving signal may be based on direct light emitted from another distance measuring device, and the process proceeds to step S2. The first arithmetic processing unit 703A determines whether or not the above-described shift in light receiving timing (difference in elapsed time) is within a predetermined time difference. If the difference is within the predetermined time difference (Y in step S2), it is determined that the received light signal is based on the reflected light reflected by the measurement object, and the outgoing light L1 emitted from the distance measuring device 7 is not determined (step S2). N), it is determined that the light receiving signal is based on the direct light emitted from another distance measuring device.

In step S1, if the intensity of the light receiving signal Ps is lower than the first threshold value Vth1 (N in step S1), the process proceeds to step S3, where the first arithmetic processing unit 703A performs the processing based on the output level of the second comparator 703E. It is determined whether the intensity of the light receiving signal Ps is equal to or greater than the second threshold value Vth1. That is, if the output level of the second comparator 703E is low, the intensity of the light receiving signal Ps is equal to or higher than the second threshold Vth2, and if the output level is high, the intensity of the light receiving signal Ps is lower than the second threshold Vth2.

If the intensity of the light receiving signal Ps is equal to or greater than the second threshold value Vth2 (Y in step S3), it is determined that the light receiving signal is based on the reflected light reflected by the measurement target object, the emitted light L1 emitted from the distance measuring device 7. . Therefore, in this case, the first arithmetic processing unit 703A performs distance measurement based on the pulse width correction. Otherwise (N in step S3), it is determined that the received light signal is based on the reflected light reflected by the object, the emitted light emitted from another distance measuring device. Therefore, distance measurement is not performed in this case.

FIG. 16 is a waveform diagram illustrating an example of the light receiving signal Ps. FIG. 16 shows a waveform with respect to an elapsed time from the timing at which the emission light L1 is emitted. The light receiving signal Ps includes the light receiving signals Psx, Psy, and Psz. The intensity of the light receiving signal Psx is equal to or more than the first threshold value Vth1. The intensity of the light receiving signal Psy is lower than the first threshold value Vth1, but equal to or higher than the second threshold value Vth2. The intensity of the light receiving signal Psz becomes lower than the second threshold value Vth2.

When only the second threshold value Vth2 of the first threshold value Vth1 and the second threshold value Vth2 is used and the intensity of the light receiving signal Ps is equal to or larger than the second threshold value Vth2, the light receiving signal is emitted from another distance measuring device. Assuming that the light may be based on direct light or reflected light, the process proceeds to a process of comparing a difference in light reception timing with a predetermined time difference, and if not, the light reception signal is reflected light by light emitted from another distance measuring device. May be determined.

That is, when the intensity of the received light signal is equal to or more than the first threshold, the distance measurement unit 703 determines whether the received light signal is based on the light reflected by the measurement target. Accordingly, when the intensity of the received light signal is equal to or greater than the first threshold, the above determination is made because the received light signal may be based on light emitted from another distance measuring device. Otherwise, the above determination is not performed, so that the processing load can be reduced.

Further, the distance measurement unit 703 makes a determination based on a comparison between a second threshold value smaller than the first threshold value and the intensity of the received light signal. If the intensity of the received light signal is smaller than the first threshold and equal to or greater than the second threshold, it is determined that the received light signal is based on the light reflected by the measurement target, and if the intensity of the received light signal is smaller than the second threshold, It is determined that the light receiving signal is based on the reflected light by the light emitted from another distance measuring device. Thereby, it is possible to appropriately determine the reflected light from the measurement target object and the reflected light due to the light emitted from another distance measuring device.

<9. Distance Measuring Device System> FIG. 17 is a schematic diagram showing an example of a configuration of a distance measuring device system configured by using a plurality of distance measuring devices according to the present embodiment.

The distance measurement device system 300 illustrated in FIG. 17 includes a distance measurement device group GR and a management device 250. The distance measuring device group GR includes a first distance measuring device 7A and a second distance measuring device 7B. The first distance measuring device 7A is mounted on the first automatic guided vehicle 15A. The second distance measuring device 7B is mounted on the second automatic guided vehicle 15B.

The first distance measuring device 7A and the first automatic guided vehicle 15A are configured similarly to the distance measuring device 7 and the automatic guided vehicle 15 described above. The second distance measuring device 7B and the second automatic guided vehicle 15B are configured similarly to the distance measuring device 7 and the automatic guided vehicle 15 described above.

The first distance measurement device 7A receives the rotation speed command CM1 from the management device 250, and sets the first rotation speed of the rotation scanning. The second distance measurement device 7B receives the rotation speed command CM2 from the management device 250, and sets the second rotation speed of the rotation scanning. The first rotation speed and the second rotation speed are set to different values. The rotation speed command is received by the

distance measurement devices

7A and 7B via, for example, the communication unit T (FIG. 6) of the automatic guided

vehicles

15A and 15B.

To describe this using a specific example, for example, assume that the first rotation speed is set to 2400 rpm and the second rotation speed is set to 2401 rpm, and the predetermined rotation angle Δθ of the rotation scanning in the

distance measuring devices

7A and 7B is set to 0. 125 °. In this case, the time interval corresponding to the predetermined rotation angle Δθ is 8.6806 μS in the first distance measuring device 7A, and 8.6679 μS in the second distance measuring device 7B.

Here, FIG. 18 shows the light receiving signal Ps1 when the emitted light L1 is emitted at the first scanning position in the first distance measuring device 7A, and the second received light signal Ps1 shifted from the first scanning position by the predetermined rotation angle Δθ in the same revolution. FIG. 7 is a waveform diagram in which a light receiving signal Ps2 when emitting outgoing light L1 at a scanning position is superimposed. That is, FIG. 18 is a diagram corresponding to FIG. 12 described above.

The light receiving signal Ps1 includes the light receiving signal Ps12 by the direct light DL2 from the second distance measuring device 7B. The light receiving signal Ps2 includes the light receiving signal Ps22 by the direct light DL2 from the second distance measuring device 7B. Since a difference occurs in the time interval corresponding to the predetermined rotation angle Δθ due to the difference between the set values of the first rotation speed and the second rotation speed described above, the light receiving signal Ps22 is eight times smaller than the light receiving signal Ps12 as shown in FIG. 0.6806 μs−8.669 μs = 3.6 ns earlier. That is, the shift ΔT between the light receiving timings of the light receiving signals Ps12 and Ps22 is 3.6 ns.

Therefore, the first arithmetic processing unit 703A in the first distance measuring device 7A determines that ΔT is not within the predetermined time difference, and determines that the received light signal is not based on the reflected light from the measurement target. That is, in the distance measuring device group GR, by setting the rotation speed of the rotational scanning to be intentionally different, direct light due to light emitted from the second distance measuring device 7B is continuously emitted in the first distance measuring device 7A. In this way, erroneous distance measurement based on the direct light DL2 from the second distance measuring device 7B can be avoided by preventing light from being received at the same timing.

When the second distance measuring device 7B receives the direct light DL1 from the first distance measuring device 7A, the light receiving signal Ps22 rises 3.6 ns later than the light receiving signal Ps12 in the specific example described above. . Therefore, the first arithmetic processing unit 703A in the second distance measurement device 7B determines that ΔT is not within the predetermined time difference, and it is possible to avoid an erroneous distance measurement based on the direct light DL1 from the first distance measurement device 7A.

The method of setting the rotation speed for each distance measuring device in the distance measuring device group may be set independently for each distance measuring device without using the management device 250.

That is, the distance measuring device group GR is a distance measuring device group including the first distance measuring device 7A and the second distance measuring device 7B. The first distance measuring device 7A and the second distance measuring device 7B include a light emitting unit 83 that includes a light emitting unit 701 and performs rotation scanning of the emitted light L1, a light receiving unit 702 that outputs a light receiving signal based on light reception, and a light emitting unit 702. A distance measuring unit 703 that measures a distance to a measurement target based on emission of the emitted light L1 and light reception by the light receiving unit 702. The first distance measurement device 7A is a distance measurement device having the above-described configuration, and includes a first rotation speed of the rotation scan by the first distance measurement device 7A, a second rotation speed of the rotation scan by the second distance measurement device 7B, Is different.

Accordingly, the first distance measuring device 7A prevents direct light from light emitted from the second distance measuring device 7B from being continuously received at the same timing, and is based on the direct light from the second distance measuring device 7B. Incorrect distance measurement can be avoided.

Further, the distance measuring unit 703 of the second distance measuring device 7B is configured to detect the shift of the light receiving timing of the light receiving signal obtained when the light projecting unit 83 emits the emitted light L1 at a plurality of scanning positions shifted by a predetermined rotation angle in the same rotation. , It is determined that the light receiving signal is based on the light reflected by the measurement object. This can prevent the second distance measuring device 7B from erroneously measuring the distance based on the direct light from the first distance measuring device 7A.

The distance measurement device system 300 includes a distance measurement device group GR and a management device 250, and the first rotation speed and the second rotation speed are based on a command from the management device 250. This makes it easy to set the rotation speed for a plurality of distance measuring devices.

<10. Others> The embodiments of the present invention have been described above. However, various modifications can be made to the embodiments within the scope of the gist of the present invention.

For example, outgoing light at each of a first scanning position, a second scanning position deviated from the first scanning position by a predetermined rotation angle Δθ, and a third scanning position deviated from the second scanning position by a predetermined rotation angle Δθ in the same revolution. The determination may be made based on the light receiving signal obtained when emitting L1. More specifically, the average value of the light receiving timing deviation between the first scanning position and the second scanning position and the light receiving timing deviation between the second scanning position and the third scanning position is calculated as an evaluation value. It is determined whether the evaluated value is within a predetermined time difference.

Further, in the above-described embodiment, an unmanned carrier is described as an example of a moving object equipped with a distance measuring device. However, the present invention is not limited to this, and the moving object is applicable to a device other than a transportation purpose, such as a cleaning robot or a monitoring robot. May be.

INDUSTRIAL APPLICATION This invention can be utilized for the automatic guided vehicle which conveys a load, for example.

DESCRIPTION OF SYMBOLS 1 ... Body, 1A ... Base, 1B ... Base part, 2 ... Cargo bed, 3L, 3R ... Support part, 4L, 4R ... Drive motor, 5L, 5R ... Drive Wheel, 6F, 6R: driven wheel, 7, 70: distance measuring device, 71: laser light source, 72: collimating lens, 73: light emitting mirror, 74: light receiving lens, 75: light receiving mirror, 76: wavelength filter, 77: light receiving element, 78: rotating housing, 79: motor, 701: laser emitting unit, 702: laser receiving unit , 702A ... APD, 702B ... amplification circuit, 703 ... distance measurement unit, 703A ... first arithmetic processing unit, 703B ... first TDC, 703C ... second TDC, 703D ... 1st comparator, 703E ... 2nd comparator, 704 ... Data communication interface, 705: second arithmetic processing unit, 706: drive unit, 80: housing, 801: transmission unit, 81: substrate, 82: wiring, 8. ..Control unit, 85 storage unit, 9 drive unit, 15, 150 automatic guided vehicle, 7A first distance measuring device, 7B second distance measuring device, 15A ... 1st automatic guided vehicle, 15B ... 2nd automatic guided vehicle, GR ... distance measuring device group, 250 ... management device, 300 ... distance measuring device system, U ... control unit , B: battery, T: communication unit, Rs: measurement range, θ: rotation scanning angle range, Δθ: predetermined rotation angle, J: rotation axis, L1 ... output Incident light, L2 ... incident light, OJ ... object to be measured

Claims

A light-emitting unit that includes a light-emitting unit and performs rotary scanning of the emitted light; a light-receiving unit that outputs a light-receiving signal based on the received light; and 部 a light-receiving unit that outputs a light-receiving signal based on the emitted light and the light-receiving unit. A distance measuring unit that measures a distance, and the distance measuring unit is a light receiving signal that is obtained when the light emitting unit emits the emitted light at a plurality of scanning positions shifted by a predetermined rotation angle in the same revolution. The distance measuring device, wherein it is determined that the light receiving signal is based on the light reflected by the object to be measured, based on a shift in light receiving timing.
The distance according to claim 1, wherein the distance measurement unit determines that the light reception signal is based on light reflected by the measurement target object when an evaluation value based on the shift of the light reception timing is within a predetermined time difference. measuring device.
3. The distance measurement unit according to claim 1, wherein when the intensity of the light reception signal is equal to or greater than a first threshold, the distance measurement unit determines whether the light reception signal is based on light reflected by the measurement target. 4. Distance measuring device.
The distance measurement device according to claim 3, wherein the distance measurement unit performs the determination based on a comparison between a second threshold smaller than the first threshold and the intensity of the light reception signal.
The distance measuring device according to claim 2, wherein the predetermined time difference is defined based on the following equation. ΔTth = (((V1 + V2 ) × Δtθ + L err × 2) × 2) / c where,? Tth: predetermined time difference, V1: the distance the moving speed of the moving body measuring device is mounted, V2: a predetermined value, Δtθ: the predetermined rotation Measurement time interval corresponding to angle, L err : maximum error of distance measurement, c: speed of light
A distance measurement device group including a first distance measurement device and a second distance measurement device, wherein the first distance measurement device and the second distance measurement device include a light emitting unit and perform rotation scanning of emitted light. A light emitting unit that outputs a light receiving signal based on light reception, and a distance measuring unit that measures a distance to a measurement target based on emission of the outgoing light and light reception by the light receiving unit. The first distance measuring device is the distance measuring device according to any one of claims 1 to 5,
A distance measurement device group, wherein a first rotation speed of the rotation scan by the first distance measurement device is different from a second rotation speed of the rotation scan by the second distance measurement device.
The distance measuring unit of the second distance measuring device is configured to detect a shift in the light receiving timing of the light receiving signal obtained when the light emitting unit emits the emitted light at a plurality of scanning positions shifted by a predetermined rotation angle in the same rotation. The distance measuring device group according to claim 6, wherein the light receiving signal is determined to be based on the light reflected by the measurement target.
A distance measurement device system, comprising: the distance measurement device group according to claim 6 or 7; and a management device, wherein the first rotation speed and the second rotation speed are based on a command from the management device. .