CN111033304A

CN111033304A - Distance measuring device and moving body

Info

Publication number: CN111033304A
Application number: CN201880053361.9A
Authority: CN
Inventors: 冈本修治; 佐伯哲夫; 直江仁志; 江川智浩; 石丸裕; 江川和穗
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-09-27
Filing date: 2018-06-21
Publication date: 2020-04-17
Also published as: WO2019064741A1

Abstract

The present invention provides a distance measuring device, comprising: a light projection unit that includes a light emitting unit and performs rotational scanning based on projection light; a light receiving section; a distance measuring unit that measures a distance to a measurement target object based on the projection of the projection light and the reception of the light by the light receiving unit; and a light emission control unit that controls the light emission unit, the light emission control unit performing control such that: in one cycle of the rotational scanning, the average power of the projected light is made constant, and the output level of the projected light and the light emission interval of the projected light are changed.

Description

Distance measuring device and moving body

Technical Field

The present invention relates to a distance measuring device and a mobile body.

Background

Currently, various distance measuring devices are being developed. For example, patent document 1 discloses the following laser radar.

The laser radar of patent document 1 includes a laser light source, a light scanning unit, a photodetector, and a distance measuring unit. The laser light source emits a laser beam. The light scanning unit scans the laser beam over the target area. The photodetector receives the laser beam reflected by the target region. The distance measuring unit measures a distance to an obstacle in the target area based on a signal output from the photodetector.

Here, a signal from the photodetector is generated as a noise signal due to stray light inside the housing, in response to emission of laser light due to a high pulse having high emission intensity. When the obstacle is at a short distance, a light receiving pulse output from the photodetector due to reflected light from the obstacle appears at a position close to the noise signal. Therefore, the light receiving pulse overlaps the noise signal, and a composite wave is generated. The distance is measured based on the time when the composite wave exceeds the threshold voltage, but the time is earlier than the time to be originally detected, and therefore an error occurs in the measured distance.

Therefore, in patent document 1, when a low pulse having a low emission intensity is emitted, the pulse width of the low pulse is made narrower than that of the high pulse. Thus, even if the obstacle is in a short distance, the light receiving pulse is less likely to overlap the noise signal. Therefore, the light receiving pulse exceeds the threshold voltage at the timing when the noise signals do not overlap, and thus, the accuracy of measuring the distance can be suppressed from being lowered.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2012-159330

Disclosure of Invention

Problems to be solved by the invention

However, in patent document 1, the object is to improve the accuracy of distance measurement for a short-distance object, but in a specific range of the scanning range, distance measurement is not performed for a long-distance object.

In view of the above situation, the present invention provides a distance measuring device capable of measuring a distance to a distant object in a specific range of a rotational scanning range.

Means for solving the problems

An exemplary distance measuring device according to the present invention includes: a light projection unit that includes a light emitting unit and performs rotational scanning based on projection light; a light receiving section; a distance measuring unit that measures a distance to a measurement target object based on the projection of the projection light and the reception of the light by the light receiving unit; and a light emission control unit that controls the light emission unit, the light emission control unit performing control such that: in one cycle of the rotational scanning, the average power of the projected light is made constant, and the output level of the projected light and the light emission interval of the projected light are changed.

Effects of the invention

According to the exemplary distance measuring apparatus of the present invention, it is possible to measure the distance of a distant object in a specific range of the rotational scanning range.

Drawings

Fig. 1 is a schematic overall perspective view of an unmanned transport vehicle according to an embodiment of the present invention.

Fig. 2 is a schematic side view of an unmanned transport vehicle according to an embodiment of the present invention.

Fig. 3 is a plan view of the unmanned transport vehicle according to the embodiment of the present invention, as viewed from above.

Fig. 4 is a schematic side sectional view of a distance measuring device according to an embodiment of the present invention.

Fig. 5 is a block diagram showing an electrical configuration of a distance measuring device according to an embodiment of the present invention.

Fig. 6 is a block diagram showing an electrical configuration of the unmanned transport vehicle according to the embodiment of the present invention.

Fig. 7 is a waveform diagram showing an example of light emission control.

Fig. 8 is a diagram showing an example of a scanning range in which distance measurement can be performed.

Fig. 9 is a diagram showing an example of a scanning range set according to the traveling direction of the unmanned transport vehicle.

Fig. 10 is a diagram showing an example of the scanning range set according to the traveling direction of the unmanned transport vehicle.

Fig. 11 is a diagram showing an example of a long-distance scanning range that is variably set.

Fig. 12 is a waveform diagram showing an example of light emission control after switching.

Fig. 13 is a waveform diagram showing an example of light emission control after switching.

Fig. 14 is a diagram showing an example of a short distance range in which distance measurement can be performed in a transport vehicle traveling on a route.

Fig. 15 is a diagram showing an example of a short distance range and a long distance range in which distance measurement can be performed in a transport vehicle traveling on a passage.

Fig. 16 is a diagram showing an example of setting a plurality of remote scanning ranges.

Detailed Description

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, an unmanned transport vehicle for transporting a load will be described as an example of a mobile body on which a distance measuring device is mounted. The automated guided vehicle is also generally called an AGV (automated guided vehicle).

< 1. integral structure of unmanned conveying vehicle

Fig. 1 is a schematic overall perspective view of an unmanned transport vehicle 15 according to an embodiment of the present invention. Fig. 2 is a schematic side view of the unmanned transport vehicle 15 according to the embodiment of the present invention. Fig. 3 is a plan view of the unmanned transport vehicle 15 according to the embodiment of the present invention, as viewed from above. The unmanned transport vehicle 15 autonomously travels by two-wheel drive to transport the cargo.

The unmanned transport vehicle 15 includes a vehicle body 1, a cargo bed 2, support

portions

3L and 3R,

drive motors

4L and 4R,

drive wheels

5L and 5R, driven

wheels

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

The vehicle body 1 is composed of a base 1A and a table 1B. A plate-shaped table portion 1B is fixed to the rear upper surface of the base portion 1A. The table portion 1B has a triangular portion Tr protruding forward. A plate-like cargo bed 2 is fixed to the upper surface of the bed portion 1B. A load can be placed on the upper surface of the load table 2. The cargo bed 2 extends forward from the bed portion 1B. Thereby, a gap S is formed between the front of the base 1A and the front of the cargo bed 2.

The distance measuring device 7 is disposed in the gap S at a position forward of the apex of the triangular portion Tr of the table portion 1B. The distance measuring device 7 is configured as a laser distance measuring instrument, and is a device that scans a laser beam and measures the distance to a measurement target. The distance measuring device 7 is used for obstacle detection, map information creation, and self position recognition, which will be described later. The detailed structure of the distance measuring device 7 itself will be described later.

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

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

The driven pulley 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 passively rotate in accordance with the rotation of the

driving wheels

5L, 5R.

The unmanned transport vehicle 15 can be moved forward and backward by rotationally driving the

drive wheels

5L and 5R by the

drive motors

4L and 4R. Further, by controlling the rotation speed of the

driving wheels

5L and 5R so as to set a difference, the direction of the unmanned transport vehicle 15 can be changed by turning the unmanned transport vehicle to the right or left.

The base 1A accommodates therein the control unit U, the battery B, and the 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 performs drive control of the

drive motors

4L, 4R. The communication unit T communicates with an external tablet terminal (not shown), for example, based on Bluetooth (registered trademark). This enables the unmanned transport vehicle 15 to be remotely operated by the tablet terminal. The battery B is composed of, for example, a lithium ion battery, and supplies electric power to each unit such as the distance measuring device 7, the control unit U, and the communication unit T.

< 2. Structure 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 distance meter includes: a laser light source 71, a collimator lens 72, a projector 73, a light-receiving lens 74, a light-receiving mirror 75, a wavelength filter 76, a light-receiving unit 77, a rotary case 78, a motor 79, a case 80, a substrate 81, and wiring 82.

The housing 80 is substantially cylindrical in appearance extending in the vertical direction, and accommodates various structures such as the laser light source 71 in an internal space. The laser light source 71 is mounted on the lower surface of the substrate 81, and the substrate 81 is fixed to the lower surface of the upper end of the case 80. The laser light source 71 emits, for example, a laser beam in the infrared region downward.

The collimator lens 72 is disposed below the laser light source 71. The collimator lens 72 forms the laser beam emitted from the laser light source 71 into parallel light and emits the parallel light downward. A light projecting mirror 73 is disposed below the collimator lens 72.

The projection lens 73 is fixed to the rotating case 78. The rotary case 78 is fixed to a shaft 79A of a motor 79 and is driven to rotate around a rotation shaft J by the motor 79. As the rotating box 78 rotates, the projector lens 73 is also driven to rotate about the rotation axis J. The projector 73 reflects the laser beam emitted from the collimator lens 72, and emits the reflected laser beam as projection light L1. Since the projection mirror 73 is rotationally driven as described above, the projection light L1 is emitted while changing the emission direction in a 360-degree range around the rotation axis J.

The case 80 has a transmission portion 801 in the middle of the vertical direction. The transmission portion 801 is made of a light-transmitting resin or the like.

The projection light L1 reflected and emitted by the light projecting mirror 73 passes through the transmission portion 801, passes through the gap S, and is emitted from the unmanned transport vehicle 15 to the outside. In the present embodiment, as shown in fig. 3, the predetermined rotational scanning angle range θ is set to 270 degrees around the rotational axis J as an example. More specifically, the range of 270 degrees includes 180 degrees forward and 45 degrees to the left and right of the rear. The projection light L1 passes through the transmission portion 801 at least in a range of 270 degrees around the rotation axis J. In the rear area where the transmission portion 801 is not disposed, the projection light L1 is blocked by the inner wall of the housing 80, the wiring 82, and the like.

The light receiving mirror 75 is fixed to the rotary casing 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 case 78. The wavelength filter 76 is located below the light receiving mirror 75 and is fixed to a rotary case 78. The light receiving unit 77 is located below the wavelength filter 76 and is fixed to the rotating case 78.

The projected light L1 emitted from the distance measuring device 7 is reflected by the object to be measured and becomes diffused light. A part of the diffused light passes through the gap S and the transmission portion 801 as incident light L2 and enters the light receiving lens 74. The incident light L2 transmitted through the light receiving lens 74 is directed to 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 unit 77. The wavelength filter 76 transmits light in the infrared region. The light receiving section 77 converts the received light into an electric signal by photoelectric conversion.

When the rotating case 78 is rotationally driven by the motor 79, the light receiving lens 74, the light receiving mirror 75, the wavelength filter 76, and the light receiving unit 77 are rotationally driven together with the light projecting mirror 73.

As shown in fig. 3, a range formed by rotating around the rotation axis J by a predetermined radius in a rotational scanning angle range θ (═ 270 degrees) is defined as a measurement range Rs. The predetermined radius is changed according to the output level of the projected light L1. When the projection light L1 is emitted in the rotational scanning angle range θ and the projection light L1 is reflected by the measurement object located in the measurement range Rs, the reflected light enters the light receiving lens 74 through the transmission unit 801 as the incident light L2.

The motor 79 is connected to the board 81 through a wiring 82, and is driven to rotate by being energized from the board 81. The motor 79 rotates the rotary case 78 at a predetermined rotation speed. For example, the rotary case 78 is rotationally driven at about 3000 rpm. The wiring 82 extends vertically along the rear inner wall of the case 80.

< 3. Electrical Structure of distance measuring device >

Next, an electrical configuration of the distance measuring device 7 will be explained. Fig. 5 is a block diagram showing 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 first arithmetic processing unit 704, a data communication interface 705, a driving unit 707, 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 light emitting section 701, the light projecting mirror 73, the rotary case 78, and the motor 79 constitute a light projecting section. The light projection unit performs rotational scanning of the projected light L1.

The laser light receiving unit 702 includes a light receiving unit 77, a comparator, not shown, that receives an electric signal output from the light receiving unit 77, and the like. The comparator is attached to the light receiving unit 77, compares the level of the electric signal with a predetermined threshold level, and outputs a measurement pulse at a High level or a Low level according to the comparison result.

The distance measuring unit 703 receives the measurement pulse output from the laser light receiving unit 702. The laser light emitting unit 701 emits a pulsed laser beam using the laser emission pulse output from the first arithmetic processing unit 704 as a trigger. At this time, the projection light L1 is emitted. When the emitted projection light L1 is reflected by the object OJ, the incident light L2 is received by the laser light receiving unit 702. A measurement pulse is generated based on the amount of light received by the laser light receiving unit 702, and the measurement pulse is output to the distance measuring unit 703.

Here, the reference pulse output together with the laser emission pulse by the first arithmetic processing unit 704 is input to the distance measuring unit 703. The distance measurement unit 703 measures the elapsed time from the rise time of the reference pulse to the rise time of the measurement pulse, and can obtain the distance to the measurement object OJ. That is, the distance measuring unit 703 measures the distance by a so-called TOF (Time Of Flight) method. The measurement result of the distance is output from the distance measurement unit 703 as measurement data.

The driving unit 707 controls the rotational driving of the motor 79. The motor 79 is rotationally driven at a predetermined rotational speed by the driving section 707. The first arithmetic processing unit 704 outputs a laser emission pulse every time the motor 79 rotates by a predetermined unit angle. Thus, every time the rotating case 78 and the projection mirror 73 rotate by a predetermined unit angle, the laser light emitting unit 701 emits light and emits projection light L1. For example, pulsed projection light L1 is projected every 0.25 degrees. I.e. eight shots between two degrees.

The first arithmetic processing unit 704 generates position information on an orthogonal coordinate system with reference to the distance measuring device 7 based on the rotational angle position of the motor 79 at the time of outputting the laser light emission pulse and measurement data obtained in accordance with the laser light emission pulse. That is, the position of the object OJ to be measured is obtained based on the rotational angle position of the projection mirror 73 and the measured distance. The position information obtained as described above is output from the first arithmetic processing unit 704 as measured distance data. In this way, by scanning the projection light L1 in the rotational scanning angle range θ, a distance image of the object OJ can be obtained.

Further, the light receiving amount of the laser light receiving unit 702 changes according to the reflectance of light in the measurement object OJ. For example, when the measurement object OJ is a black object and the reflectance of light is reduced, the amount of light received is reduced and the rise of the measurement pulse is delayed. Thus, the distance is measured by the distance measuring unit 703 to be long. In this way, the measured distance changes depending on the reflectance of light at the object OJ to be measured even if the distance is substantially the same. Here, when the amount of light received decreases, the length of the measurement pulse becomes shorter. Therefore, the first arithmetic processing unit 704 corrects the measurement data according to the length of the measurement pulse, and the distance measurement accuracy can be improved. The first arithmetic processing unit 704 uses the corrected measurement data when generating the measurement distance data.

The measured distance data output from the first arithmetic processing unit 704 is transmitted to the unmanned transport vehicle 15 shown in fig. 6 described later via the data communication interface 705.

< 4. Electrical Structure of unmanned conveying vehicle

As described above, the electrical configuration on the distance measuring device 7 side is explained, and here, the electrical configuration on the unmanned transport vehicle 15 side is explained with reference to fig. 6. Fig. 6 is a block diagram showing an electrical configuration of the unmanned transport vehicle 15.

As shown in fig. 6, the unmanned transport vehicle 15 includes: a distance measuring device 7, a control unit 8, a drive unit 9, and a communication unit T.

The control unit 8 is provided in the control unit U (fig. 1). The drive unit 9 includes a motor driver, drive

motors

4L and 4R, and the like, which are not shown. The motor driver is provided in the control unit U. The control unit 8 controls the drive unit 9 to issue a command. The driving unit 9 controls the rotation speed and rotation 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 section 8 can receive an operation signal corresponding to the content operated on the tablet terminal via the communication section T.

The control unit 8 receives the measured distance data output from the distance measuring device 7. The control section 8 can create map information based on the measured distance data. The map information is information generated for identifying the position of the unmanned transport vehicle 15, and is generated as position information of a stationary object in the place where the unmanned transport vehicle 15 travels. For example, when the location where the unmanned transport vehicle 15 travels is a warehouse, the stationary objects are walls of the warehouse, racks arranged in the warehouse, and the like.

The map information is generated when the unmanned transport vehicle 15 is manually operated by, for example, a tablet terminal. In this case, an operation signal corresponding to an operation of, for example, an operation lever 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 based on the operation signal to control the travel of the unmanned transport vehicle 15. At this time, the control unit 8 specifies the position of the measurement target object at the location where the unmanned transport vehicle 15 travels as map information based on the measured distance data input from the distance measuring device 7 and the position of the unmanned transport vehicle 15. The position of the unmanned transport 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 input from the distance measuring device 7 with map information stored in the storage unit 85 in advance, and thereby performs self-position recognition for specifying the self position of the unmanned transport vehicle 15. That is, the control unit 8 functions as a position recognition unit. By performing the self-position recognition, the control unit 8 can perform autonomous travel control of the unmanned transport vehicle 15 along a predetermined path.

< 5. control of light emission >

Next, the light emission control of the projection light L1 performed by the distance measuring device 7 of the present embodiment will be described. The first arithmetic processing unit 704 controls the laser light emitting unit 701 to control the emission of the projection light L1. That is, the first arithmetic processing unit 704 functions as a light emission control unit.

Fig. 7 is a diagram illustrating an example of light emission control of the projection light L1 according to the present embodiment. In fig. 7, the horizontal axis represents time, and the vertical axis represents the output level of the projected light L1. As shown in fig. 7, the projected light L1 emits light in a pulse shape.

In the example shown in fig. 7, in one period T, there are included: a range t1 of predetermined output levels, a range t2 adjacent after the range t1 and higher in output level than the range t1, and a range t3 adjacent after the range t2 and lower in output level than the range t 2. In the range t1 and the range t3, the output level is the same. In the range t2, the light emission interval is longer than in the ranges t1 and t 3. In one period T, the width of the light emission pulse is constant. Thus, the average power Pa is the same for each of the ranges t1 to t 3.

In the example of fig. 7, the output level is 2 times in the range t2 compared with the ranges t1 and t3, and therefore the light emission interval is 2 times. The rotation speed of the rotational scanning by the motor 79 is constant, and therefore, the light emission pulse is generated at each larger rotation angle in the range t2 than in the ranges t1, t 3. For example, in the ranges t1 and t3, when it is set that the light emission pulse is generated every 0.25 degrees, the light emission pulse is generated every 0.5 degrees in the range t 2. Therefore, in the ranges t1, t3, the angular resolution of the distance measurement is high.

Fig. 8 shows a scanning range corresponding to the light emission control of fig. 7. The range t1 in fig. 7 corresponds to the short-distance scanning range R1 shown in fig. 8. The range t2 in fig. 7 corresponds to the remote scanning range R2 shown in fig. 8. The range t3 in fig. 7 corresponds to the short-distance scanning range R3 shown in fig. 8. In the scanning range R2, distance measurement can be performed for an object located at a long distance. That is, in a specific range of the rotational scanning range, distance measurement can be performed for a distant object.

In the control shown in fig. 7, the first arithmetic processing unit 704 may calculate an average value of the measured distances for each of two light emission pulses adjacent in time in the low output level ranges t1 and t3, and output the measured distance data based on the calculated average value from the data communication interface 705. At this time, the first arithmetic processing unit 704 outputs measurement distance data based on the distance measured for each light emission pulse in the high output level range t 2. That is, in the range t2, the average value of the distances is not calculated.

Thus, the reduction in angular resolution of distance measurement in the long-distance range corresponding to the range t2 can be suppressed.

< 6. setting about scanning Range >

The scanning range shown in fig. 8 is an example, and the setting control of the scanning range in the light emission control described above can be performed as follows, for example.

The control unit 8 of the unmanned transport vehicle 15 transmits, for example, drive information of the

drive motors

4L and 4R to the distance measuring device 7 as movement information of the unmanned transport vehicle 15, and transmits path information stored in the storage unit 85 to the distance measuring device 7 as movement information. That is, the control unit 8 functions as a transmission unit that transmits movement information related to the movement of the unmanned transport vehicle 15.

The first arithmetic processing unit 704 of the distance measuring device 7 raises the output level of the light emission pulse within a predetermined scanning range including the traveling direction of the unmanned transport vehicle 15 based on the movement information sent from the control unit 8. And decreasing the output level in a scanning range other than the predetermined scanning range. That is, the ranges t1 to t3 in fig. 7 described above are variably set.

In the example shown in fig. 9, a setting example of the scanning range when the traveling direction D1 of the unmanned transport vehicle 15 is set to the straight traveling direction is shown. The output level is increased within a predetermined scanning range including the traveling direction D1, and a long-distance scanning range R2 is set, and short-distance scanning ranges R1 and R3 are set outside the predetermined scanning range.

In the example shown in fig. 10, a setting example of the scanning range when the traveling direction D2 of the unmanned transport vehicle 15 is set to the straight traveling direction and the turning direction is shown. The output level is increased within a predetermined scanning range including the traveling direction D2, and a long-distance scanning range R2 is set, and short-distance scanning ranges R1 and R3 are set outside the predetermined scanning range.

This enables distance measurement in a long distance range including the traveling direction of the unmanned transport vehicle 15, and the state of a long-distance object can be monitored. For example, when an object detected in a remote range approaches the unmanned transport vehicle 15, the unmanned transport vehicle 15 can be decelerated. This can suppress collision of the unmanned transport vehicle 15 with the object.

The first arithmetic processing unit 704 may obtain moving speed information on the moving speed of the unmanned transport vehicle 15 from the control unit 8, and variably control the output level within the predetermined scanning range in which the output level is increased based on the moving speed information. Specifically, the output level is increased as the moving speed is higher.

Further, in this case, the first arithmetic processing unit 704 may be configured to narrow the predetermined range in which the output level is increased as the moving speed is higher.

For example, fig. 11 shows the long-distance scanning ranges R2 and R21 set within a predetermined scanning range including the traveling direction D1. The scanning range R21 is set when the moving speed is faster than the scanning range R2, and the output level is increased, so the distance from the remote location becomes longer. Further, at this time, the scanning range R21 is set to a range narrower than the scanning range R2.

By setting the scanning range R21 in this way when the moving speed is high, it is possible to measure the distance of an object at a longer distance and suppress collision between the unmanned transport vehicle 15 and the object. Further, by setting the scanning range R21 to be narrow, even if the output level is increased, the average power of the projected light L1 for one cycle can be suppressed.

< 7. switching on control >

In the present embodiment, switching from the above-described light emission control to another control described below may be performed.

Fig. 12 is a waveform diagram showing an example of light emission control after switching from the light emission control shown in the example of fig. 7. In fig. 12, in the range T12, the output level of the light emission pulse is increased as compared with the ranges T11 and T13 in one period T. In the range t11 to t13, the light emission interval is constant. Therefore, the average power in each of the ranges t11, t13 and the average power in the range t12 are different. In the ranges t11, t13 in which the output level is low, the output level is lower than the ranges t1, t3 in which the output level is low as shown in fig. 7.

Therefore, in the control after the switching in the example shown in fig. 12, since the light emission interval is constant, the reduction of the angular resolution in the range t12 in which the output level is high can be suppressed. In addition, in the ranges t11, t13 of the low output level, the output level is further lowered, and therefore, even if the light emission interval is constant, the increase of the average power in one cycle can be suppressed.

For example, when the control unit 8 detects that the distance from the current position of the unmanned transport vehicle 15 to an object such as a wall is closer than a predetermined distance based on the map information stored in the storage unit 85, the control unit notifies the first arithmetic processing unit 704 of the information, and the first arithmetic processing unit 704 switches the light emission control. In this case, in the light emission control after the switching, the output level is further decreased in the range of the low output level, and the distance in the short-distance scanning range is further shortened. However, light emission control is performed in a situation where there is no problem even in distance measurement in a range of a shorter distance.

As shown in fig. 13, the light emission interval may be longer than that in fig. 12 in the low output level ranges t11 and t 13. That is, in the light emission control after the switching, the light emission interval at a low output level may be made variable.

In this way, for example, when the position of the unmanned transport vehicle 15 is a very close distance from a wall or the like, the distance information of the object measured in the close range can be appropriately thinned out by increasing the light emission interval at a low output level as shown in fig. 13. The map information is constituted by position information at predetermined intervals. When the light emission interval is short, the measured position data (measured distance data) is position data having a narrower interval than the map information, and therefore, a step of thinning out the measured data is necessary when the self position is recognized. Therefore, in the case of a short distance, by increasing the light emission interval, the measurement data can be thinned out in advance, and the above-described data thinning-out process can be prevented.

< 8. identification about self position >

As described above, the control unit 8 can perform self-position recognition based on the comparison between the map information stored in the storage unit 85 and the measured distance data. In this case, the light emission control shown in the example of fig. 7 can be used.

For example, when the unmanned transport vehicle 15 moves on the long continuous path 50 as shown in fig. 14, and light emission control is performed at a low output level all the time in one cycle, the scanning range is the short distance range Rn, and therefore, the distance is measured only for the path 50 located at the short distance. Therefore, even if the obtained measurement distance data and the map information are compared, the own position is not clear.

Therefore, in such a case, if the light emission control is switched to the light emission control shown in the example of fig. 7 described above, the scanning range includes the short-distance scanning ranges R1 and R3 and the long-distance scanning range R2 as shown in fig. 15, and therefore, the distance can be measured not only for the via 50 but also for the wall 51 located on the deep side of the via 50. Therefore, if the obtained measured distance data and the map information are compared, the own position can be identified from the detection of the wall 51 as the characteristic object.

< 9. multiple Range settings for high output levels >

In the light emission control of the example shown in fig. 7, the range T2 for setting the output level high in one period T is single, but a plurality of ranges for setting the output level high may be set.

For example, as shown in fig. 16, the distance measuring device 7 may be mounted on a vehicle 60. In this case, the first arithmetic processing unit 704 of the distance measuring device 7 sets two high output level ranges in one cycle. As shown in fig. 16, the short-distance scanning ranges R101, R102, and R103 are set in accordance with the range of the low output level set in one cycle. Then, the long-distance scanning ranges R201 and R202 are set based on the two high output level ranges set.

Thus, as shown in fig. 16, when the automobile 60 arrives at the intersection, by setting the remote scanning ranges R201 and R202, it is possible to measure the distance of an object such as an automobile located on the right and left of the automobile 60. This can improve the safety of driving the automobile 60.

< 10 > action Effect of the present embodiment

As described above, the distance measuring device 7 of the present embodiment includes: a light projection unit that includes a light emitting unit 701 and performs rotational scanning based on projection light L1; a light receiving unit 702; a distance measuring unit 703 for measuring a distance to the object to be measured based on the projection of the projection light and the reception of the light by the light receiving unit; and a light emission control unit 704 for controlling the light emission unit. The light emission control unit performs the following control: in one cycle of the rotational scanning, the average power of the projected light is made constant, and the output level of the projected light and the light emission interval of the projected light are changed.

With this configuration, the distance of the object at a long distance can be measured within a specific range of the rotational scanning range.

Further, the distance measurement device is provided with distance measurement

data output units

704 and 705 that output distance measurement data based on the distance measurement result of the distance measurement unit 703, wherein the distance measurement data output unit takes the average value of the distance measurement results based on the temporally adjacent light emitting units as the distance measurement data in the range where the output level in the control is low, and takes the distance measurement result for each light emitting unit as the distance measurement data in the range where the output level in the control is high.

This can suppress a decrease in angular resolution of distance measurement in a long distance range.

Further, the light emission control unit 704 may switch from the control to a mode in which the light emission interval is constant and the output level is variable, in one cycle of the rotational scanning, and the low output level in the mode may be lower than the low output level in the control.

Thus, in the above mode, a decrease in angular resolution in a range in which the output level is high can be suppressed. In the above mode, the low output level is set to a lower level, and therefore, even if the light emission interval is constant, the increase in average power can be suppressed. With regard to the short distance, the above-described mode can be used in a situation where there is no problem even in distance measurement of a range of a shorter distance.

In the above mode, the light emission control unit 704 may change the light emission interval at the low output level.

Thus, when the distance measuring device is very close to the object, the distance information of the object to be measured can be appropriately thinned out by extending the light emission interval of the low output level. For example, the map information is constituted by position information at predetermined intervals. When the light emission interval is short, the measured position data is position data having an interval narrower than the map information, and therefore, a step of thinning out the measured data is required for identifying the position of the mobile terminal. Therefore, in the case of a short distance, by increasing the light emission interval, the measurement data can be thinned out in advance, and the above-described data thinning-out process can be prevented.

In the above control, the output level is higher in a plurality of ranges. This enables distance measurement to be performed in a plurality of specific long-distance ranges.

The moving body 15 of the present embodiment includes: the distance measuring device 7 of any of the above structures; and a transmission unit 8 that transmits movement information related to the movement of the moving body to the distance measuring device, wherein the light emission control unit 704 increases the output level in a predetermined rotational scanning range including a traveling direction of the moving body based on the movement information.

Accordingly, distance measurement in a range including a long distance in the traveling direction of the moving body can be performed, and thus collision of the moving body with the object can be suppressed.

The light emission control unit 704 increases the output level in a range where the output level is high as the moving speed of the moving body 15 is higher. As a result, the distance measurement in a longer distance range can be performed as the moving speed of the moving body is higher, and collision with the object can be suppressed.

The light emission control unit 704 narrows a range in which the output level is high as the moving speed of the moving body 15 is higher. This makes it possible to suppress an increase in average power even if the output level is increased.

The moving body 15 of the present embodiment includes: a distance measuring device 7 having any of the above configurations, including measured distance

data output units

704 and 705 that output measured distance data based on a distance measurement result of the distance measuring unit 703; and a position recognition unit 8 for recognizing the position of the mobile terminal itself based on the comparison between the map information and the measured distance data.

Thus, when a moving object travels in a place where the same scenery continues, it is possible to suppress the self position from being unclear by detecting a distant specific object.

The moving body is preferably a transport vehicle. This is because the transport vehicle generally travels in a place where an obstacle exists and performs autonomous travel.

< 11. other >)

While the embodiments of the present invention have been described above, the embodiments can be variously modified within the scope of the present invention.

For example, in the above-described embodiment, the unmanned transport vehicle was described as an example of the movable body, but the movable body is not limited to this, and the movable body may be applied to devices other than transport applications such as a cleaning robot and a monitoring robot.

Industrial applicability of the invention

The present invention can be used for an unmanned transport vehicle for transporting goods, for example.

Description of the symbols

1-vehicle body, 1A-base, 1B-table, 2-cargo table, 3L, 3R-support, 4L, 4R-drive motor, 5L, 5R-drive wheel, 6F, 6R-driven wheel, 7-distance measuring device, 71-laser light source, 72-collimator lens, 73-projector lens, 74-light receiving lens, 75-light receiving lens, 76-wavelength filter, 77-light receiving section, 78-rotating box, 79-motor, 701-laser light emitting section, 702-laser light receiving section, 703-distance measuring section, 704-first arithmetic processing section, 705-data communication interface, 707-drive section, 80-box, 801-transmission section, 81-substrate, 82-wiring, 8-control section, 85-storage section, 9-drive section, 15-unmanned conveyance vehicle, U-control unit, B-battery, T-communication section, S-gap, Rs-measuring range, θ -rotational scan angle range, J-rotation axis, L1-projection light, L2-incident light, OJ-measurement object.

Claims

1. A distance measuring device is characterized in that,

the disclosed device is provided with: a light projection unit that includes a light emitting unit and performs rotational scanning based on projection light; a light receiving section; a distance measuring unit that measures a distance to a measurement target object based on the projection of the projection light and the reception of the light by the light receiving unit; and a light emission control unit for controlling the light emission unit,

the light emission control unit performs the following control: in one cycle of the rotational scanning, the average power of the projected light is made constant, and the output level of the projected light and the light emission interval of the projected light are changed.

2. Distance measuring device according to claim 1,

further comprising a measured distance data output unit for outputting measured distance data based on the distance measurement result of the distance measurement unit,

the measured distance data output unit may use an average value of the distance measurement results based on the temporally adjacent light emitting units as the measured distance data in a range where the output level of the control is low, and use the distance measurement result for each light emitting unit as the measured distance data in a range where the output level of the control is high.

3. The distance measuring apparatus according to claim 1 or 2,

the light emission control section may switch from the control to a mode in which the light emission interval is constant and the output level is variable in one cycle of the rotational scanning,

the low output level in the mode is lower than the low output level in the control.

4. Distance measuring device according to claim 3,

the light emission control unit may change the light emission interval at the low output level in the mode.

5. The distance measuring apparatus according to any one of claims 1 to 4,

in the control, the output level is higher in a plurality of ranges.

6. A movable body characterized in that a movable body is provided,

the disclosed device is provided with: the distance measuring device of any one of claims 1 to 5; and a transmission unit for transmitting movement information related to the movement of the mobile body to the distance measuring device,

the light emission control unit increases the output level of a predetermined rotational scanning range including a traveling direction of the moving object based on the movement information.

7. The movable body according to claim 6,

the light emission control unit increases the output level in a range in which the output level is high as the moving speed of the moving body is higher.

8. The movable body according to claim 7,

the light emission control unit narrows a range in which the output level is high as the moving speed of the moving body is higher.

9. A movable body characterized in that a movable body is provided,

the disclosed device is provided with: the distance measuring device according to any one of claims 1 to 5, comprising a measured distance data output unit that outputs measured distance data based on a distance measurement result of the distance measuring unit; and a position recognition unit that recognizes the position of the mobile terminal based on a comparison between the map information and the measured distance data.

10. The movable body according to any one of claims 6 to 8,

the moving body is a transport vehicle.

11. The movable body according to claim 9,

the moving body is a transport vehicle.