WO2020071465A1

WO2020071465A1 - Distance measurement device

Info

Publication number: WO2020071465A1
Application number: PCT/JP2019/039044
Authority: WO
Inventors: 和穂江川; 岡本　修治; 石丸　裕; 智浩江川; 佐伯　哲夫; 裕多堀
Original assignee: 日本電産株式会社
Priority date: 2018-10-05
Filing date: 2019-10-03
Publication date: 2020-04-09
Also published as: JPWO2020071465A1

Abstract

This distance measurement device comprises a distance measurement unit that measured the distance to a measurement object on the basis of emission of emitted light and reception by a light-receiving unit. The distance measurement unit is capable of conducting a distance measurement in which there is used a first correction method for performing correction in accordance with detection of both the beginning and the end of a light-reception signal, and a distance measurement in which there is used a second correction method for performing correction in accordance with detection of one of the beginning and the end of the light-reception signal. The distance measurement unit outputs, as a measured distance, a distance measured using the second correction method on the basis of a distance comparison process in which there is used, from among a distance measured using the first correction method and the distance measured using the second correction method, at least the distance measured using the first correction method.

Description

Distance measuring device

The present invention relates to a distance measuring device.

Conventionally, various distance measuring devices have been developed. For example, Patent Document 1 discloses the following signal processing device for a distance measuring device.

The signal processing device disclosed in Patent Document 1 corresponds to a light projecting unit that outputs pulsed measurement light to a measurement target space via an optical window by detecting reflected light from an object to be measured existing in the measurement target space. And a light receiving unit that outputs a reflected signal to be processed.

The signal processing device includes a differential processing unit, a waveform determination unit, and a calculation unit. The differentiation processing section differentiates the reflection signal output from the light receiving section. The waveform judging section is configured to determine the reflected light based on the rising and falling characteristics of the first-order differential reflection signal obtained by first-order differentiation of the reflected signal by the differentiation processing section and the rising characteristic of the second-order differential reflection signal obtained by secondarily differentiating the reflected signal. Is a reflected light from a plurality of objects to be measured is a superimposed reflected light. The calculation unit calculates and outputs the distance to the device under test based on the reflection signal according to the determination result by the waveform determination unit.

Japanese Unexamined Patent Publication: JP-A-2011-215005

When a translucent reflector such as glass exists between the distance measuring device and the object to be truly detected, and when the reflector is close to the object to be measured, a reflection signal from the object is reflected. There is a possibility that an accurate distance to the object to be measured that is superimposed on a reflected signal from the object to be detected and cannot be accurately calculated may be calculated. In such a case, according to Patent Document 1, the distance to the object to be measured is reduced. It is said that it is possible to calculate accurately. Further, in Patent Literature 1, the same applies to a case where an object smaller than the beam of measurement light, such as a tree branch, is not limited to the translucent reflector, but is located between the distance measuring device and the object to be measured. And

However, in Patent Document 1, there is no problem to improve the distance measurement accuracy of the translucent reflector or the small object. Further, in Patent Document 1, it is necessary to detect a situation in which the distance to the measured object may not be accurately calculated based on the processing by the differential processing unit, so that the calculation processing load increases. That is, in Patent Document 1, there is a possibility that the calculation load is large and the distance measurement accuracy is insufficient depending on the characteristics of the distance measurement target.

In view of the above situation, an object of the present invention is to provide a distance measuring device capable of improving the distance measuring accuracy while suppressing the processing load and irrespective of the characteristics of the distance measuring object.

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. A distance measurement unit that measures a distance to a measurement target based on light reception by the first and second light sources, wherein the distance measurement unit performs correction in accordance with detection of both rising and falling in the light reception signal. It is possible to perform the measurement of the distance using a method and the measurement of the distance using the second correction method that performs correction according to the detection of one of the rising edge and the falling edge in the light receiving signal, The distance measurement unit is configured to calculate at least the distance measured using the first correction method, of the distance measured using the first correction method and the distance measured using the second correction method. Based on the distance comparison processing used, the second And outputs the distance measured by using a positive method as the measurement distance.

According to the exemplary distance measuring device of the present invention, it is possible to improve the distance measuring accuracy while suppressing the processing load.

FIG. 1 is a diagram illustrating an example of an ideal light receiving signal and an actual light receiving signal. FIG. 2 is a diagram of a light receiving signal for explaining pulse width correction. FIG. 3 is a diagram of a light receiving signal for explaining slew rate correction. FIG. 4 is a diagram illustrating an example of a light-transmitting object and emission of light emitted to the object. FIG. 5 is a diagram illustrating an example of emission of emitted light to non-light-transmitting objects located on the near side and the far side. FIG. 6 is a waveform diagram illustrating an example of a case where two light receiving signal components are separated. FIG. 7 is a waveform diagram showing an example of a case where two light receiving signal components overlap. FIG. 8 is a diagram illustrating an example of a relationship between a preset pulse width used for pulse width correction and a correction amount. FIG. 9 is a diagram illustrating an example of a relationship between the emission angle of the laser light and the measurement distance by the pulse width correction in the situation illustrated in FIG. FIG. 10 is a schematic overall perspective view of the automatic guided vehicle according to one embodiment of the present invention. FIG. 11 is a schematic side view of the automatic guided vehicle according to one embodiment of the present invention. FIG. 12 is a plan view of the automatic guided vehicle according to one embodiment of the present invention as viewed from above. FIG. 13 is a schematic side sectional view of the distance measuring device. FIG. 14 is a block diagram illustrating an electrical configuration of the distance measuring device. FIG. 15 is a block diagram illustrating an electrical configuration of the automatic guided vehicle. FIG. 16 is a block diagram illustrating a first configuration example of the distance measurement unit. FIG. 17 is a diagram showing the relationship between the light receiving signal and each threshold (reference voltage). FIG. 18 is a diagram illustrating an example of rotational scanning of emitted light by the distance measuring device. FIG. 19 is a flowchart relating to a first example of the distance measurement control process. FIG. 20 is a flowchart relating to a first example of the distance measurement control process. FIG. 21 is a diagram illustrating an example of distance measurement on a wall protruding forward. FIG. 22 is a diagram illustrating an example of a case where the attitude of the distance measurement device changes. FIG. 23 is a diagram illustrating another example of the case where the distance measurement device changes its posture. FIG. 24 is a block diagram illustrating a second configuration example of the distance measurement unit. FIG. 25 is a flowchart relating to a second example of the distance measurement control process. FIG. 26 is a flowchart relating to a third example of the distance measurement control process. FIG. 27 is a flowchart relating to a third example of the distance measurement control process.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.

<1. Distance Correction Method> First, a distance correction method used for distance measurement in the present embodiment will be described. In the distance measurement according to the present embodiment, the distance is acquired by emitting a laser beam and receiving the reflected light reflected by the measurement target object, and measuring the time from emission to light reception.

Ideally, the light receiving signal has a pulse waveform like the light receiving signal Ps' shown in FIG. In this case, the distance to the measurement target can be accurately measured by measuring the elapsed time T 'from the emission timing t0 of the laser light to the rising timing of the light receiving signal Ps'.

However, in reality, like the light receiving signal Ps shown in FIG. 1, the light receiving signal has a rising edge and a falling edge having an inclination with respect to time. Thus, an accurate distance to the measurement target cannot be measured only by measuring the elapsed time T from the laser light emission timing t0 to the rising timing of the light receiving signal Ps. Therefore, it is necessary to correct the elapsed time T by the correction amount ΔT, with the time from when the light receiving signal Ps shown in FIG. 1 rises from the zero level to the predetermined level as the correction amount ΔT. That is, it is necessary to subtract the correction amount ΔT from the elapsed time T.

Further, even at the same distance, the peak of the received light signal Ps increases or decreases due to a difference in the reflectance of the measurement target or the like. The rising and falling slopes of the light receiving signal Ps change according to the increase and decrease of the peak of the light receiving signal Ps, and the correction amount ΔT changes. Therefore, it is necessary to consider such a change in the correction amount ΔT for accurate distance measurement.

In the present embodiment, pulse width correction and slew rate correction are employed as a method for correcting the distance.

First, the pulse width correction as the first correction method will be described using the waveform of the light receiving signal Ps shown in FIG. In the pulse width correction, the elapsed time T1 from the laser light emission timing t0 to the timing t1 at which the light receiving signal Ps rises and crosses the first threshold Vth1, and the light receiving signal Ps falls from the laser light emission timing t0 to the first threshold An elapsed time T2 up to a timing t2 crossing Vth1 is measured. Then, the pulse width W is calculated from the difference between the elapsed times T1 and T2.

As the peak of the light receiving signal Ps increases, the rising and falling slopes of the light receiving signal Ps become steeper, the pulse width W increases, and the correction amount ΔT decreases. The correction amount ΔT is the time from when the light receiving signal Ps rises from the zero level to the first threshold value Vth1. Therefore, the correction amount ΔT is determined from the relationship between the preset pulse width W and the correction amount ΔT and the actually calculated pulse width W. The distance is measured by subtracting the determined correction amount ΔT from the measured elapsed time T1.

The light receiving signal Ps is inverted, and the elapsed time from the laser light emission timing t0 to the timing t1 at which the light receiving signal Ps falls and crosses the first threshold value, and the light receiving signal Ps rises from the laser light emitting timing t0 The pulse width W may be calculated by measuring the elapsed time until the timing t2 crossing the first threshold.

That is, the first correction method performs the correction in accordance with both the detection of the rising edge and the falling edge of the received light signal.

Next, the slew rate correction as the second correction method will be described using the waveform of the light receiving signal Ps shown in FIG. In the slew rate correction, the elapsed time T11 from the laser light emission timing t0 to the timing t1 at which the light receiving signal Ps rises and crosses the first threshold Vth1, and the light receiving signal Ps rises from the laser light emission timing t0 to the second threshold Vth2 And the elapsed time T12 up to the timing t12 crossing. Note that the second threshold value Vth2 is larger than the first threshold value Vth1. Then, the slew rate SR is calculated from the difference between the elapsed times T11 and T12.

As the peak of the light receiving signal Ps increases, the rising slope of the light receiving signal Ps becomes steeper, the slew rate SR decreases, and the correction amount ΔT decreases. The correction amount ΔT is the time from when the light receiving signal Ps rises from the zero level to the first threshold value Vth1. Therefore, the correction amount ΔT is determined from the relationship between the preset slew rate SR and the correction amount ΔT and the actually calculated slew rate SR. The distance is measured by subtracting the determined correction amount ΔT from the measured elapsed time T11.

Note that the light receiving signal Ps is inverted so that the elapsed time from the laser light emission timing t0 to the timing at which the light receiving signal Ps falls and crosses the first threshold value, and the time at which the laser light emitting timing t0 causes the light receiving signal Ps to fall The slew rate SR may be calculated by measuring the elapsed time until the timing when the second threshold (<first threshold) is crossed.

That is, the second correction method performs correction according to detection of one of the rising edge and the falling edge of the received light signal.

As described above, the first correction method is a pulse width correction in which the correction is performed based on the time between the timing at which the rising crosses the first threshold value and the timing at which the falling crosses the first threshold value. Is a slew rate correction that performs correction based on the time between the timings at which the rise or fall crosses the first threshold and the second threshold, respectively. As a result, the processing load for correction can be reduced.

<2. Problems of Distance Correction Method> Here, as shown in FIG. 4, when another object 250 exists behind a light-transmitting object 200 that transmits light, such as glass, when the laser light L is emitted, The reflected light reflected by the sexual object 200 and the reflected light reflected by the rear object 250 are received.

When the distance between the translucent object 200 and the rear object 250 is long, as shown in FIG. 6, in the light reception signal Ps, the light reception signal component Ps200 due to the light reflected by the light transmission object 200 and the rear object The light receiving signal component Ps250 due to the reflected light at 250 is separated in time. For this reason, since the rising and falling of the light receiving signal component Ps200 cross the first threshold value Vth1, the accurate pulse width W1 can be calculated, and the accurate distance to the translucent object 200 is measured by the pulse width correction. It becomes possible.

However, when the distance between the translucent object 200 and the rear object 250 is short, the light receiving signal component Ps200 and the light receiving signal component Ps250 overlap as shown in the upper part of FIG. As a result, as shown in the lower part of FIG. 7, the light receiving signal Ps is generated by combining the light receiving signal component Ps200 and the light receiving signal component Ps250. Therefore, the pulse width W2 calculated as a period from the time when the light receiving signal Ps rises to cross the first threshold Vth1 to the time when the light receiving signal Ps falls to cross the first threshold Vth1 is longer than the accurate pulse width W1. Become.

Here, FIG. 8 is a diagram illustrating an example of a relationship between a preset pulse width W used for pulse width correction and a correction amount ΔT. As shown in FIG. 8, the correction amount ΔT determined by the above relationship with the pulse width W2 is smaller by the error ΔTerr than the correction amount ΔT determined by the accurate pulse width W1 and the above relationship. Therefore, when the distance is measured by the pulse width correction, the distance to the translucent object 200 is measured to be longer than the actual distance.

FIG. 9 is a diagram illustrating an example of a relationship between the emission angle θ _L of the laser beam L and the measurement distance D by the pulse width correction in the situation illustrated in FIG. Note that the emission angle θ _L indicates a deviation angle of the emission direction of the laser light L from the front direction with respect to the translucent object 200.

When the emission angle θ _L is small, the amount of reflected light from the translucent object 200 is large, and the amount of reflected light from the object 250 is small, so that an accurate pulse width can be detected. The distance to the translucent object 200 can be accurately measured by the width correction.

When the emission angle θ _L further increases, the amount of light reflected from the translucent object 200 decreases and the amount of light reflected from the object 250 increases, so that the phenomenon shown in FIG. 7 occurs. As a result, the pulse width is detected to be longer, the correction amount decreases, and the distance to the translucent object 200 is measured to be longer than the actual distance, as in the hatched portion shown in FIG. A distance position at which the distance is measured to be longer when pulse width correction is used as in the hatched portion is referred to as an intermediate point MP.

When the emission angle θ _L is further increased, the amount of reflected light from the translucent object 200 is further reduced, and the amount of reflected light from the object 250 is further increased. Therefore, an accurate pulse width of the object 250 can be detected, as shown in FIG. Like a black portion, the distance to the object 250 can be accurately measured by pulse width correction.

A similar phenomenon is that, for example, the laser beam L is emitted when there is a non-translucent object 300 such as a front wall shown in FIG. 5 and a non-translucent object 350 such as a rear wall. It can happen in some cases. The non-translucent object 300 may be a thin object such as a chair leg, in addition to a wall.

As described above, there is a problem that the use of the pulse width correction may cause an intermediate point. However, in the case of the slew rate correction, even if the situation shown in FIG. Since the rate is calculated, the slew rate can be accurately obtained. Therefore, an accurate distance can be measured. However, when the slew rate correction is used, the rising edge cannot be detected unless the peak of the light receiving signal is sufficiently large, so that the range in which the distance can be measured is smaller than that in the pulse width correction.

Therefore, the distance measuring device of the present embodiment is configured to use the respective advantages of the pulse width correction and the slew rate correction.

<3. Overall configuration of automatic guided vehicle> The distance measuring device of the present embodiment will be described in detail below. 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).

FIG. 10 is a schematic overall perspective view of the automatic guided vehicle 15 according to one embodiment of the present invention. FIG. 11 is a schematic side view of the automatic guided vehicle 15 according to one embodiment of the present invention. FIG. 12 is a plan view of the automatic guided vehicle 15 according to one embodiment of the present invention as viewed from above. 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. Further, by rotating the

drive wheels

5L and 5R in the opposite direction, the automatic guided vehicle 15 can be rotated on the spot.

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.

<4. Configuration of Distance Measuring Device> FIG. 13 is a schematic side sectional view of the distance measuring device 7. The distance measuring device 13 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. 12, a range formed by rotating around the rotation axis J with a predetermined radius in the rotation scanning angle range θ (270 degrees as an example) is defined as the measurement range Rs. 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.

<5. Electrical Configuration of Distance Measuring Apparatus> Next, the electrical configuration of the distance measuring apparatus 7 will be described. FIG. 14 is a block diagram illustrating an electrical configuration of the distance measuring device 7.

As shown in FIG. 14, the distance measuring device 7 includes a laser emitting unit 701, a laser 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. 13), 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 projecting unit 83 (FIG. 13). 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. 13) 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. 14) output together with the laser emission pulse LP. The distance measuring 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 and falling timings of the light receiving signal. That is, the distance measuring unit 703 measures the distance by a so-called TOF (Time @ Of @ Flight) method. The distance measurement unit 703 performs distance measurement using the above-described pulse width correction and slew rate correction. 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 measurement unit 703 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. 12 shows the emission of the emission light L1.

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.

<6. Electrical Configuration of Unmanned Attached Vehicle> As described above, the electrical configuration of the distance measuring device 7 has been described. Here, the electrical configuration of the automated guided vehicle 15 will be described with reference to FIG. FIG. 15 is a block diagram illustrating an electrical configuration of the automatic guided vehicle 15.

As illustrated in FIG. 15, 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. 10). 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 an operation signal according to the content operated on the tablet terminal via the communication unit T.

The control unit 8 receives the measured distance data DT output from the distance measuring device 7. 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.

<7. First Configuration Example of Distance Measurement Unit> FIG. 16 is a block diagram showing a first configuration example of the distance measurement unit 703. FIG. 16 also shows a specific configuration example of the laser light receiving unit 702. FIG. 17 shows the relationship between the light receiving signal Ps and each threshold (reference voltage).

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 comparator 703B, a second comparator 703C, a first TDC (time to digital converter) 703D, a second TDC 703E, and a selector 703F, in addition to the first arithmetic processing unit 703A described above. Have.

The first comparator 703B 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 (-). The output signal of the first comparator 703B is input to the first TDC 703D and to the selector 703F. The second comparator 703C compares the light receiving signal Ps input to the non-inverting input terminal (+) with the second threshold value Vth2 input to the inverting input terminal (-). The output signal of the second comparator 703C is input to the selector 703F. The second threshold value Vth2 is larger than the first threshold value Vth1.

The first TDC 703D measures a first elapsed time T10 (FIG. 17) from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A to the rising timing of the output signal input from the first comparator 703B to High. I do. The selector 703F selects one of the output signal of the first comparator 703B and the output signal of the second comparator 703C in accordance with the selection signal SS output from the first arithmetic processing unit 703A, and outputs the selected output signal to the Input to 2TDC703E.

When the output signal of the first comparator 703B is selected and input from the selector 703F, the second TDC 703E outputs the Low of the output signal input from the selector 703F from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A. The second elapsed time T20 (FIG. 17) until the falling timing of the time is measured.

When the output signal of the second comparator 703C is selected and input from the selector 703F, the second TDC 703E outputs the High of the output signal input from the selector 703F from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A. A third elapsed time T30 (FIG. 17) up to the rising timing of the measurement is measured.

When the output signal of the first comparator 703B is selected by the selection signal SS, the first arithmetic processing unit 703A calculates the pulse width from the difference between the first elapsed time T10 and the second elapsed time T20 to correct the pulse width. To measure the distance. On the other hand, when the output signal of the second comparator 703C is selected by the selection signal SS, the first arithmetic processing unit 703A calculates the through rate by calculating the slew rate from the difference between the first elapsed time T10 and the third elapsed time T30. Perform distance measurement by rate correction. Therefore, the distance measurement unit 703 can perform the distance measurement using the first correction method and the distance measurement using the second correction method.

That is, the distance measurement unit 703 includes a first comparator 703B that compares the received light signal Ps with the first reference voltage Vth1, a second comparator 703C that compares the received light signal Ps with the second reference voltage Vth2, a reference pulse SP, and a first comparator 703C. A first TDC 703D to which the output of the comparator 703B is input, a second TDC 703E to which the reference pulse Ps is input, and a selector 703F which selects one of the output of the first comparator 703B and the output of the second comparator 703C and outputs the selected signal to the second TDC 703E. And Thus, the distance measurement unit 703 can switch between pulse width correction as the first correction method and slew rate correction as the second correction method.

<8. First Example of Distance Measurement Control Process> Next, the distance measurement control process by the distance measurement unit 703 (FIG. 16) according to the above-described first configuration example will be described with reference to the flowcharts shown in FIGS.

Here, FIG. 18 is a diagram illustrating an example of rotational scanning of the emitted light L1 by the distance measuring device 7. The distance measuring device 7 emits the emission light L1 at each scanning position shifted by a predetermined unit angle in the rotation scanning angle range θ of 270 ° as an example. In FIG. 18, the emitted light L1 is emitted while shifting the scanning position counterclockwise. Each scanning position is represented as an angular position n (n = 1 to N).

The flowcharts shown in FIGS. 19 and 20 show processing for each angular position n shown in FIG. When the power is turned on, the processing shown in FIG. 19 is started, and thereafter, the processing is continued until the power is turned off. In addition, m shown in FIGS. 19 and 20 indicates the rotation of the rotation scanning. When the process shown in FIG. 19 is started, m = 0.

When the circuit shifts to the next circuit in step S1, the first arithmetic processing unit 703A performs distance measurement by pulse width correction by selecting the output signal of the first comparator 703B by the selection signal SS in step S2. Then, in step S3, the first arithmetic processing unit 703A outputs the distance measured in step S2.

Next, proceeding to step S4, if the distance acquired in step S2 is an error (YES in step S4), the first arithmetic processing unit 703A performs a pulse in step S2 in the next round (step S1). Distance measurement by width correction is performed. Note that the error refers to a case where distance measurement cannot be performed because the distance to the measurement target is long, the peak of the light receiving signal Ps is too small, and the light receiving signal Ps does not exceed the first threshold Vth1.

On the other hand, if the acquisition distance is not an error in step S4 (NO in step S4), the process proceeds to step S5. In step S5, the first arithmetic processing unit 703A calculates a difference between the distance obtained in step S2 and the distance obtained at the immediately preceding angular position (n-1). Here, when distance measurement is performed at the intermediate point MP as shown in FIG. 9 described above, the difference from the distance at the immediately preceding angular position becomes large.

Here, as shown in FIG. 4 described above, the measurement object includes a light-transmitting object 200 and an object 250 located on the back side of the light-transmitting object. This makes it possible to detect an intermediate point caused by the overlap of the light reception signal component due to the light reflected by the light transmissive object and the light reception signal component due to the light transmitted through the light transmissive object and reflected by the object located on the back side. .

Further, as shown in FIG. 5 described above, the measurement target includes a non-light-transmitting object 300 and another non-light-transmitting object 350 located on the back side of the non-light-transmitting object. This makes it possible to detect an intermediate point caused by the overlap of the light receiving signal component due to the reflected light from the non-light-transmitting object and the light receiving signal component due to the light reflected from the other non-light-transmitting object.

Therefore, if the difference value calculated in step S5 is not smaller than the set value (NO in step S6), it is determined that an intermediate point has been detected, and the process proceeds to step S8 in the next round (step S7). In step S8, the first arithmetic processing unit 703A performs distance measurement by slew rate correction by selecting the output signal of the second comparator 703C using the selection signal SS. Then, in step S9, the first arithmetic processing unit 703A outputs the distance measured in step S8.

On the other hand, if the difference value calculated in step S5 is equal to or smaller than the set value (YES in step S6), it is determined that the intermediate point has not been detected, and in the next round (step S1), the pulse in step S2 is determined. Distance measurement by width correction is performed.

As described above, when the intermediate point is detected, the distance measurement is switched to the distance measurement by the slew rate correction with high distance measurement accuracy at the intermediate point, and otherwise, the distance measurement is performed by the pulse width correction having a large distance measurable range. .

In step S5, if the difference cannot be calculated because the acquired distance at the immediately preceding angular position is an error, the process proceeds to steps S1 and S2. If the angular position n = 1, there is no immediately preceding angular position, so the process proceeds to steps S1 and S2.

That is, the distance measurement unit 703 performs at least the first correction of the distance measured using the first correction method (pulse width correction) and the distance measured using the second correction method (slew rate correction). Based on the distance comparison processing using the distance measured using the technique, the distance measured using the second correction technique is output as the measured distance.

As a result, the received light signal component based on the reflected light from the first object and the received light signal component based on the reflected light from the second object overlap, so that the distance position where the distance is measured to be longer when the first correction method is used is increased. When the (intermediate point) is detected, it is possible to output a measured distance using the second correction method that can more accurately measure the distance. Since the detection of the intermediate point is based on the distance comparison processing, the processing load can be reduced.

More specifically, the distance measurement unit 703 determines that the distance measured by using the first correction method at the first angular position (n−1) in the rotational scan and that the scan should be performed later than the first angular position in the rotational scan. Is compared with the distance measured using the first correction method at the second angle position (n), and based on the comparison result, the distance measured using the second correction method is calculated at the second angle position. Is output as the measured distance.

The first angular position (n-1) and the second angular position (n) are adjacent angular positions. Note that the adjacent angular positions are the respective angular positions of the temporally adjacent timings among the timings at which the emission light is emitted in the rotational scanning. Thereby, the intermediate point can be detected with high accuracy.

Further, based on the above comparison result, the distance measuring unit 703 calculates the second angle of the (m + 1) th rotation following the mth rotation (m is a natural number) whose distance has been measured at the second angular position using the first correction method. The method used for distance measurement at the position is switched from the first correction method to the second correction method.

This makes it possible to realize a distance measurement using one of the first correction method and the second correction method at an angular position of the same revolution, thereby simplifying the configuration.

Further, the distance measurement unit 703 calculates a difference between the distance measured at the first angular position and the distance measured at the second angular position using the first correction method, and obtains a calculation result obtained by calculating the difference between the first angular position and the first angular position. If the predetermined value is exceeded, the method used for measuring the distance at the second angular position of the (m + 1) rotation is switched from the first correction method to the second correction method.

Thus, the intermediate point can be detected when the difference between the distance measured at the first angular position and the distance measured at the second angular position exceeds the first predetermined value.

Further, when the above calculation result is equal to or smaller than the first predetermined value, the distance measurement unit 703 sets a method used for distance measurement at the second angular position of the (m + 1) th rotation as a first correction method.

As a result, the measurable range of the distance can be ensured by using the first correction method except for the intermediate point.

After step S9, in step S10, if the distance acquired in step S8 is an error (YES in step S10), in the next round (step S1), distance measurement by pulse width correction is performed in step S2. . Note that the error refers to a case where the distance to the measurement target is long, the peak of the light receiving signal Ps is too small, and the distance cannot be measured because the light receiving signal Ps does not exceed the second threshold value Vth2.

On the other hand, if the acquisition distance is not an error in step S10 (NO in step S10), the process proceeds to step S11 shown in FIG. In step S11, the first arithmetic processing unit 703A determines whether or not the distance measurement in the immediately preceding round is based on pulse width correction. If the distance measurement in the immediately preceding lap is pulse width correction (YES in step S11), the process proceeds to step S12, where the first arithmetic processing unit 703A determines the distance acquired in step S8 and the immediately preceding lap. Calculate the difference from the distance obtained in.

Here, for example, when the distance of an object having an inclination such as a wall protruding forward as shown in FIG. 21 is measured, the difference value calculated in step S5 increases (NO in step S6), and the difference value is calculated at the intermediate point. May be erroneously detected. In this case, the difference value calculated in step S12 becomes small, so that erroneous detection of the intermediate point can be detected.

Therefore, if the difference value calculated in step S12 is equal to or smaller than the set value (YES in step S13), in the next round (step S1), distance measurement by pulse width correction is performed in step S2.

That is, the distance measurement unit 703 calculates the difference between the distance measured using the second correction method at the (m + 1) -turn second angular position and the distance measured at the m-th round second angular position. If the calculated result obtained is equal to or less than the second predetermined value, the method used for the distance measurement used at the (m + 2) -th second angular position following the (m + 1) -th rotation is changed from the second correction method to the second correction method. Switch to one correction method.

Thereby, when it is confirmed that the detected intermediate point is not actually the intermediate point, the range can be measured by returning to the first correction method.

On the other hand, when the distance measurement of the immediately preceding circuit is not based on the pulse width correction (NO in step S11), or when the difference value is not smaller than the set value (NO in step S13), the process proceeds to step S14.

In step S14, the first arithmetic processing unit 703A calculates a difference value by subtracting the distance obtained at the immediately preceding angular position from the distance obtained in step S8.

Here, as shown in FIG. 22, the emitted light L1 emitted at the angular position n due to a change in the attitude of the automatic guided vehicle 15 including the distance measuring device 7 causes an object positioned behind the translucent object 400 to be positioned. The outgoing light L1 that has been directed toward 450 and emitted at the immediately preceding angular position (n−1) may be directed toward the translucent object 400. In this case, the distance obtained at the angular position n is longer than the distance obtained at the angular position (n-1), and the difference value calculated in step S14 is a positive value.

Therefore, if the calculated difference value is not less than the set value (NO in step S15) and the difference value is a positive value (YES in step S16), in the next round (step S1). In step S2, distance measurement is performed by pulse width correction.

That is, the distance measurement unit 703 determines that the difference value obtained by subtracting the distance measured at the first angular position from the distance measured using the second correction method at the second angular position exceeds the third predetermined value and is positive. If the value is the value, the method used for the distance measurement used at the second angular position in the next circuit is switched from the second correction method to the first correction method.

Thereby, when the posture of the distance measuring device 7 changes, and the distance measurement target at the second angular position changes from an object having an intermediate point to a more distant object, by returning to the first correction method, The range where distance can be measured can be secured.

When the calculated difference value is equal to or smaller than the set value (YES in step S15), or when the calculated difference value is not equal to or smaller than the set value but is not a positive value (NO in step S16). ), And proceed to step S17.

In step S17, the first arithmetic processing unit 703A calculates a difference value by subtracting the distance acquired in step S8 from the distance acquired in the immediately following angular position.

Here, as shown in FIG. 23, due to a change in the attitude of the automatic guided vehicle 15 including the distance measuring device 7, the emitted light L1 emitted at the angular position n is an object positioned behind the translucent object 400. The outgoing light L <b> 1 that is directed to 450 and emitted at the immediately subsequent angular position (n + 1) may be in a state of being directed to the translucent object 400. In this case, the distance obtained at the angular position n is longer than the distance obtained at the angular position (n + 1), and the difference value calculated at step S17 is a negative value.

Therefore, if the calculated difference value is not smaller than the set value (NO in step S18) and the difference value is a negative value (YES in step S19), the next round (step S1). In step S2, distance measurement is performed by pulse width correction.

That is, the distance measuring unit 703 subtracts the distance measured using the second correction method at the second angular position from the distance measured at the third angular position that is later in the scanning order than the second angular position. If the difference value is greater than the fourth predetermined value and is a negative value, the method used for distance measurement used at the second angular position in the next round is changed from the second correction method to the first correction method. Switch to

When the calculated difference value is equal to or smaller than the set value (YES in step S18), or when the calculated difference value is not equal to or smaller than the set value but is not a negative value (NO in step S19). ), In the next round (step S7), distance measurement by slew rate correction is performed in step S8.

<9. Second Configuration Example of Distance Measurement Unit> FIG. 24 is a block diagram showing a second configuration example of the distance measurement unit 703. The distance measuring unit 703 according to the second configuration example shown in FIG. 24 has a third TDC 703G instead of the selector 703F as a configuration difference from the first configuration example shown in FIG.

The output signal of the first comparator 703B is input to the second TDC 703E. The output signal of the second comparator 703C is input to the third TDC 703G together with the reference pulse SP.

The first TDC 703D measures a first elapsed time T10 (FIG. 17) from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A to the rising timing of the output signal input from the first comparator 703B to High. I do. The second TDC 703E calculates a second elapsed time T20 (FIG. 17) from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A to the falling timing of the output signal input from the first comparator 703B to Low. measure. The third TDC 703G measures a third elapsed time T30 (FIG. 17) from the rising timing of the reference pulse SP output from the first arithmetic processing unit 703A to the rising timing of the output signal input from the second comparator 703C to High. I do.

The first arithmetic processing unit 703A calculates the pulse width from the difference between the first elapsed time T10 and the second elapsed time T20, performs distance measurement by pulse width correction, and performs the first elapsed time T10 and the third elapsed time. By calculating the slew rate from the difference from T30, distance measurement by slew rate correction is performed. Therefore, according to this configuration example, it is possible to acquire the distances by both correction methods at the same angular position in the same revolution.

That is, the distance measurement unit 703 can perform the distance measurement using the first correction method and the distance measurement using the second correction method at the same angular position in the rotation scan of the same rotation. .

The distance measuring unit 703 includes a first comparator 703B for comparing the received light signal with the first reference voltage Vth1, a second comparator 703C for comparing the received light signal with the second reference voltage Vth2, a reference pulse SP and the first comparator 703B. The first TDC 703D to which the output of the first comparator 703B is inputted, the second TDC 703E to which the reference pulse SP and the output of the first comparator 703B are inputted, and the third TDG to which the reference pulse SP and the output of the second comparator 703C are inputted. Have.

Thus, distance measurement using both the first correction method and the second correction method at the same angular position in the same circuit can be realized with a simple configuration.

<10. Second Example of Distance Measurement Control Process> Next, the distance measurement control process by the distance measurement unit 703 (FIG. 24) according to the above-described second configuration example will be described with reference to the flowchart shown in FIG.

The flowchart shown in FIG. 25 shows the processing for each angular position n shown in FIG. 18 described above. When the power is turned on, the processing shown in FIG. 25 is started, and thereafter, the processing is continued until the power is turned off. Further, m shown in FIG. 25 indicates the rotation of the rotation scanning. When the process shown in FIG. 25 is started, m = 0.

When the lap moves to the next lap in step S21, in step S22, the first arithmetic processing unit 703A performs distance measurement by pulse width correction. Then, in step S23, the first arithmetic processing unit 703A performs distance measurement by slew rate correction.

In step S24, the first arithmetic processing unit 703A determines whether the distance obtained by the slew rate correction is an error. If the distance is an error (YES in step S24), the process proceeds to step S27. In step S27, the first arithmetic processing unit 703A outputs the distance measured by the pulse width correction. Thereafter, the process proceeds to the next round (step S21).

On the other hand, if the distance obtained by the slew rate correction is not an error (NO in step S24), the process proceeds to step S25, where the first arithmetic processing unit 703A calculates the distance obtained by the pulse width correction in step S22, In step S23, a difference from the distance acquired by the slew rate correction is calculated.

If the difference value calculated in step S25 is not smaller than or equal to the set value (NO in step S26), it is determined that an intermediate point has been detected, the process proceeds to step S28, and the first arithmetic processing unit 703A measures the difference by slew rate correction. Output distance. Thereafter, the process proceeds to the next round (step S21).

On the other hand, if the difference value is equal to or smaller than the set value (YES in step S26), it is determined that the intermediate point has not been detected, and the process proceeds to step S27, where the first arithmetic processing unit 703A measures the difference by the pulse width correction. Output distance.

That is, the distance measurement unit 703 compares the distance measured using the first correction method and the distance measured using the second correction method at the same angular position, and based on the comparison result, The distance measured using the two correction method is output as the measured distance.

As a result, the received light signal component based on the reflected light from the first object and the received light signal component based on the reflected light from the second object overlap, so that the distance position where the distance is measured to be longer when the first correction method is used is increased. When the (intermediate point) is detected, it is possible to output a measured distance using the second correction method that can more accurately measure the distance. The detection of the intermediate point can be performed by a method that suppresses the processing load. In addition, the real-time property of the measured distance data can be improved.

<11. Third Example of Distance Measurement Control Process> Next, a modified example of the distance measurement control process by the distance measurement unit 703 (FIG. 16) according to the above-described first configuration example will be described with reference to the flowcharts shown in FIGS. I do. In order to perform the process, the first arithmetic processing unit 703A needs to have a buffer (storage unit) (not shown).

The flowcharts shown in FIGS. 26 and 27 show the above-described processing for each angular position n shown in FIG. When the power is turned on, the processing shown in FIG. 26 is started, and thereafter, the processing is continued until the power is turned off. In addition, m shown in FIG. 26 indicates the rotation of the rotation scanning. When the process shown in FIG. 26 is started, m = 0, and the first arithmetic processing unit 703A holds m as a variable.

When the process shown in FIG. 26 is started, first, in step S31, the first arithmetic processing unit 703A determines whether m is greater than 3, and if m is greater (YES in step S31), the process proceeds to step S32. , The first arithmetic processing unit 703A outputs the latest measured distance stored in the buffer. At this time, the first arithmetic processing unit 703A deletes the measured distance stored in the buffer and initializes the variable m to 0.

After step S32, or when m is 3 or less in step S31 (NO in step S31), the process proceeds to step S33, and the first arithmetic processing unit 703A increases the variable m by one.

Thereafter, the process proceeds to step S34, where the first arithmetic processing unit 703A determines whether m is greater than 3, and if m is greater (YES in step S34), the process proceeds to step S35. In step S35, the first arithmetic processing unit 703A determines whether the measurement method in the (m-1) circuit is different from the measurement method in the (m-2) circuit. NO), and proceed to step S38.

On the other hand, if the measurement method is different (YES in step S35), the process proceeds to step S36, where the first arithmetic processing unit 703A obtains the distance acquired in (m-1) revolutions and the distance acquired in (m-2) revolutions. Calculate the difference from the distance. The first arithmetic processing unit 703A determines whether the calculated difference value is equal to or less than the set value, and if it is equal to or less than the set value (YES in step S37), the process proceeds to step S38. If the difference value is not smaller than the set value (NO in step S37), the process proceeds to step S42.

In step S38, the first arithmetic processing unit 703A performs distance measurement by pulse width correction. Here, the first arithmetic processing unit 703A stores the acquired distance in the buffer. If the distance acquired in step S38 is an error (YES in step S39), the process returns to step S31.

On the other hand, if the distance acquired in step S38 is not an error (NO in step S39), the process proceeds to step S40. In step S40, the first arithmetic processing unit 703A calculates a difference between the distance obtained in step S38 and the distance obtained at the immediately preceding angular position (n-1).

In step S41, the first arithmetic processing unit 703A determines whether the calculated difference value is equal to or smaller than the set value. If the calculated difference value is equal to or smaller than the set value (YES in step S41), the process returns to step S31. On the other hand, if the calculated difference value is not smaller than the set value (NO in step S41), the process proceeds to step S42.

In step S42, the first arithmetic processing unit 703A determines whether m is greater than 3; if m is greater than 3 (YES in step S42), the process proceeds to step S43, where the first arithmetic processing unit 703A is stored in the buffer. The latest measured distance is output. At this time, the first arithmetic processing unit 703A deletes the measured distance stored in the buffer and initializes the variable m to 0.

After step S43, or when m is equal to or smaller than 3 in step S42 (NO in step S42), the process proceeds to step S44, and the first arithmetic processing unit 703A increases the variable m by one.

Then, in step S45, the first arithmetic processing unit 703A performs distance measurement by slew rate correction. Here, the first arithmetic processing unit 703A stores the acquired distance in the buffer. If the distance acquired in step S45 is an error (YES in step S46), the process returns to step S31.

On the other hand, if the distance acquired in step S45 is not an error (NO in step S46), the process proceeds to step S47 in FIG. The processing in steps S47 to S55 is the same as the processing in steps S11 to S19 in FIG. 20 described above. In the case of YES in step S49 or YES in step S55, the process returns to step S31. If YES in step S54 or NO in step S55, the process returns to step S42.

That is, the distance measurement device 7 further includes a storage unit (buffer) that stores the distance measured at the second angle position using the first correction method, and the distance measurement unit 703 determines that the calculation result is the first predetermined value. In the following cases (YES in step S41), the distance stored in the storage unit is output (step S32).

As a result, the distance measured by using the first correction method at the second angle position is output after detecting that the point is not the intermediate point. Therefore, when the first correction method is not appropriate, the first correction method is used. Output of the measured distance can be avoided.

<12. 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, the second correction method is not limited to the slew rate correction, and a method of performing correction based on, for example, differential processing of a received light signal may be employed. In this case, the first derivative may be performed at the rising or falling of the light receiving signal, so that the calculation load can be suppressed as compared with the conventional method that needs to perform the first differentiation and the second differentiation.

Further, in the above-described embodiment, an unmanned carrier is described as an example of a moving body equipped with a distance measuring device. However, the present invention is not limited to this. 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: 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 ... rotary housing, 79 ... motor, 701 ... laser emitting part, 702 ... laser receiving part, 702A ... APD, 702B ... amplifier circuit, 703 ... distance measuring unit, 703A ... first arithmetic processing unit, 703B ... first comparator, 703C ... second comparator, 703D ... 1st TDC, 703E ... 2nd TDC, 703F ... cell 703G: third TDC, 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 automatic guided vehicle, U control unit, B Battery, T: communication unit, Rs: measurement range, θ: rotation scanning angle range, J: rotation axis, L1: outgoing light, L2: incident light, OJ ... Measurement object, 200, 400: translucent object, 250, 450: object, 300, 350: non-translucent object

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 A distance measuring unit for measuring a distance, and the distance measuring unit measures the distance using a first correction method for performing correction in accordance with detection of both rising and falling in the light receiving signal, and A distance measurement using a second correction method for performing correction in accordance with detection of one of the rising edge and the falling edge in a signal. Based on a distance comparison process using at least the distance measured using the first correction method, of the distance measured using the second correction method and the distance measured using the second correction method. Measured using correction method And it outputs the distance as measurement distance, the distance measuring device.
The distance measurement unit is configured to detect a distance measured by using the first correction method at a first angular position in the rotational scan, and a second angular position at which scanning is performed later than the first angular position in the rotational scan. Comparing the distance measured using the first correction method, and outputting the distance measured using the second correction method as the measurement distance at the second angular position based on the comparison result; The distance measuring device according to claim 1.
The distance measurement unit is configured to measure the distance at the second angular position using the first correction method based on the comparison result, and to perform the second (m + 1) -th rotation of the second (m is a natural number) rotation. The distance measuring apparatus according to claim 2, wherein a method used for measuring a distance at an angular position is switched from the first correction method to the second correction method.
The distance measuring unit calculates a difference between a distance measured at the first angular position and a distance measured at the second angular position using the first correction method, and calculates a difference obtained by calculating a difference between the distance measured at the second angular position and the distance measured at the second angular position. 4. The distance according to claim 3, wherein when the value exceeds a predetermined value, a method used for measuring a distance at the second angular position in the (m + 1) rotation is switched from the first correction method to the second correction method. 5. measuring device.
If the calculation result is equal to or less than the first predetermined value, the distance measurement unit may use, as the first correction method, a method used for measuring the distance at the second angular position of the (m + 1) th rotation. Item 5. The distance measuring device according to Item 4.
A storage unit that stores a distance measured by using the first correction method at the second angular position, wherein the distance measurement unit is configured to store the distance when the calculation result is equal to or less than the first predetermined value. The distance measurement device according to claim 5, wherein the distance stored in the distance measurement device is output.
The distance measurement unit is configured to calculate a difference between a distance measured using the second correction method at the second angular position of the (m + 1) rotation and a distance measured at the second angular position of the mth rotation. When the calculation result obtained by calculating the second angle position is equal to or less than a second predetermined value, the method used for measuring the distance used at the second angular position in the (m + 2) th turn following the (m + 1) th turn is the The distance measurement device according to claim 3, wherein the distance measurement device is switched from the two correction methods to the first correction method.
The distance measuring unit is configured such that a difference value obtained by subtracting a distance measured at the first angular position from a distance measured at the second angular position using the second correction method exceeds a third predetermined value and is positive. The method according to any one of claims 3 to 7, wherein the method used for distance measurement used at the second angular position in the next round is switched from the second correction method to the first correction method when the value is The distance measuring device according to claim 1.
The distance measuring unit subtracts a distance measured using the second correction method at the second angular position from a distance measured at a third angular position that is later in the scanning order than the second angular position. Calculating a difference value, and when the difference value is greater than a fourth predetermined value and is a negative value, a method used for measuring a distance used at the second angular position in the next round from the second correction method. The distance measuring apparatus according to any one of claims 3 to 8, which switches to a first correction method.
The distance measuring unit includes: a first comparator that compares the received light signal with a first reference voltage; a second comparator that compares the received light signal with a second reference voltage; and a reference pulse and an output of the first comparator. A first TDC (time to digital converter), a second TDC to which the reference pulse is input, and a selector for selecting one of the output of the first comparator and the output of the second comparator and outputting the selected output to the second TDC. The distance measuring device according to any one of claims 3 to 9, comprising:
The distance measuring device according to any one of claims 2 to 10, wherein the first angular position and the second angular position are adjacent angular positions.
The distance measurement unit can perform distance measurement using the first correction method and distance measurement using the second correction method at the same angular position in the same rotation of the rotational scan. Yes, the distance measurement unit compares the distance measured using the first correction method and the distance measured using the second correction method at the same angular position, and based on the comparison result. The distance measuring device according to claim 1, wherein a distance measured using the second correction method is output as a measured distance.
The distance measuring unit includes: a first comparator that compares the received light signal with a first reference voltage; a second comparator that compares the received light signal with a second reference voltage; and a reference pulse and an output of the first comparator. A first TDC (time to digital converter), {a second TDC to which the reference pulse and the output of the first comparator are input, and} a third TDC to which the reference pulse and the output of the second comparator are input. The distance measuring device according to claim 12, comprising:
The distance measuring device according to any one of claims 1 to 13, wherein the measurement target includes a light-transmitting object and an object located on the back side of the light-transmitting object.
The measurement object according to any one of claims 1 to 13, wherein the measurement target includes a non-light-transmitting object and another non-light-transmitting object located on the back side of the non-light-transmitting object. The distance measuring device as described.
The first correction method is a pulse width correction for performing correction based on a time between a timing at which the rising crosses a first threshold value and a timing at which the falling crosses the first threshold value. The method according to any one of claims 1 to 15, wherein the method is a slew rate correction that performs correction based on a time between timings at which the rise or the fall crosses the first threshold and the second threshold, respectively. The distance measuring device as described.