CN111033313A

CN111033313A - Distance measuring device and moving body provided with same

Info

Publication number: CN111033313A
Application number: CN201880052842.8A
Authority: CN
Inventors: 石丸裕; 佐伯哲夫; 直江仁志; 江川智浩; 冈本修治; 江川和穗
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-09-25
Filing date: 2018-06-21
Publication date: 2020-04-17
Also published as: JPWO2019058678A1; WO2019058678A1

Abstract

The distance measuring device of the present invention includes: a light projecting section that emits projection light as pulsed light toward an object to be measured; a disturbance light detection sensor that detects intensity of disturbance light different from the projection light; a light receiving unit that receives the disturbance light and the projection light reflected by the measurement target and converts the received disturbance light and the projection light into an electrical signal; a comparison unit which compares the level of the electric signal of the projection light with a predetermined threshold value and binarizes the level; a distance measuring unit that measures a distance to the measurement target based on a comparison result of the comparing unit; and a threshold value changing unit that changes the threshold value according to the intensity of the disturbance light.

Description

Distance measuring device and moving body provided with same

Technical Field

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

Background

For example, patent document 1 discloses a vehicle distance measuring device mounted on a vehicle (mobile body). The distance measuring device for a vehicle includes an irradiation unit, a reception unit, a propagation delay time measuring unit, and a distance calculating unit. The irradiation unit generates and irradiates an electromagnetic wave. The receiving unit receives a reflected wave of the electromagnetic wave reflected by the obstacle and generates a received signal. The propagation delay time measuring means holds a comparison value (threshold level) set to be a value serving as a comparison reference larger when the propagation delay time from the irradiation to the reception is shorter than when the propagation delay time is longer. At this time, the comparison value is determined in advance based on the light reception signal caused by the disturbance such as fog or rain.

The propagation delay time measuring unit compares the received signal with the comparison value, recognizes a time when the received signal is equal to or greater than the comparison value as a reception detection time, and counts the propagation delay time from the time of irradiation by the irradiation unit to the reception detection time. The distance calculation unit calculates a distance between the obstacle and the host vehicle based on the propagation delay time.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 8-304535

However, according to the conventional vehicle distance measuring device (distance measuring device) described above, there is a possibility that the comparison value is set to be high in advance. In this case, even when the light reception signal due to actual disturbance is small at the time of distance measurement, the comparison value is maintained high, and there is a possibility that the light reception signal due to the reflected wave on the obstacle (object to be measured) of the electromagnetic wave is evaluated relatively small. In the conventional vehicle distance measuring device, for example, when the comparison value is set in consideration of disturbance light such as sunlight, the comparison value may be set to be high in advance. Therefore, the distance measurement by the vehicle distance measuring device is inaccurate, and the reliability of the vehicle distance measuring device is reduced.

Disclosure of Invention

The invention aims to provide a distance measuring device capable of improving reliability and a moving body with the distance measuring device.

An exemplary distance measuring device according to the present invention includes: a light projecting section that emits projection light as pulsed light toward an object to be measured; a disturbance light detection sensor that detects intensity of disturbance light different from the projection light; a light receiving unit that receives the disturbance light and the projection light reflected by the measurement target and converts the received disturbance light and the projection light into an electrical signal; a comparison unit which compares the level of the electric signal of the projection light with a predetermined threshold value and binarizes the level; a distance measuring unit that measures a distance to the measurement target based on a comparison result of the comparing unit; and a threshold value changing unit that changes the threshold value in accordance with the intensity of the disturbance light.

An exemplary movable body of the present invention includes the distance measuring device having the above-described configuration.

Effects of the invention

According to the exemplary distance measuring device and the mobile body of the present invention, reliability can be improved.

Drawings

Fig. 1 is a perspective view of an automated guided vehicle including a distance measuring device according to an embodiment of the present invention.

Fig. 2 is a side view of an automated guided vehicle including a distance measuring device according to an embodiment of the present invention.

Fig. 3 is a plan view of an automated guided vehicle including a distance measuring device according to an embodiment of the present invention.

Fig. 4 is a 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 waveform diagram showing an electric signal amplified by the amplifying unit of the distance measuring device according to the embodiment of the present invention.

Fig. 7 is a waveform diagram showing an electric signal in a case where the electric signal of the light received by the light receiving unit is amplified without cutting off the dc component in the presence of the disturbance light.

Fig. 8 is a block diagram showing an electrical configuration of an automated guided vehicle according to an embodiment of the present invention.

Fig. 9 is a block diagram showing an electrical configuration of a distance measuring device according to a modification of the embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings. Here, an example in which the distance measuring device is configured as a laser range finder is described. In addition, an example of a mobile body on which the distance measuring device is mounted is an automated guided vehicle for transporting a load. An Automated Guided Vehicle (AGV) is also generally referred to as an Automated guided vehicle.

< 1. integral structure of automated guided vehicle

Fig. 1 is a perspective view showing an automated guided vehicle 15 including a distance measuring device 7 according to an embodiment of the present invention. Fig. 2 is a side view of an automated guided vehicle 15 including a distance measuring device 7 according to an embodiment of the present invention. Fig. 3 is a plan view of the distance measuring device 7 according to the embodiment of the present invention, as viewed from above the automated guided vehicle 15. The automated guided vehicle 15 automatically travels and carries goods by two-wheel drive. In particular, the automated guided vehicle 15 can rotate on site.

The automated guided vehicle 15 includes a vehicle body 1, a luggage rack 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 platform 1B. A plate-shaped stand portion 1B is fixed to the rear upper surface of the base portion 1A. The stand portion 1B has a triangular portion Tr protruding forward. The plate-like luggage rack 2 is fixed to the upper surface of the rack portion 1B. The luggage rack 2 can be loaded with cargo on its upper surface. The luggage rack 2 extends further forward than the rack portion 1B. Thus, a gap S is formed between the front portion of the base 1A and the front portion of the luggage rack 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 gantry portion 1B. The distance measuring device 7 is configured as a laser distance measuring instrument, and is a device that measures the distance to the measurement target while scanning the laser light. The distance measuring device 7 is used for mapping information creation and self-position recognition 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. As an example, the drive motor 4L is constituted by an AC servomotor. The drive motor 4L incorporates a reduction gear (not shown). The drive wheel 5L is fixed to a shaft on which the drive motor 4L rotates.

The support portion 3R is fixed to the right side of the base portion 1A, and supports the drive motor 4R. As an example, the drive motor 4R is constituted by an AC servomotor. The drive motor 4R incorporates a reduction gear (not shown). The drive wheel 5R is fixed to a shaft on which the drive motor 4R rotates.

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

wheels

6F, 6R passively rotate in accordance with the rotation of

drive wheels

5L, 5R.

The

drive motors

4L and 4R rotationally drive the

drive wheels

5L and 5R, thereby enabling the automated guided vehicle 15 to move forward and backward. Further, by controlling the rotational speeds of the

drive wheels

5L and 5R to be different from each other, the automated guided vehicle 15 can be turned right or left to change the direction.

The base 1A accommodates 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 performs drive control of the

drive motors

4L, 4R. The communication unit T communicates with an external tablet terminal (not shown), for example, by Bluetooth (registered trademark). Therefore, the automated guided vehicle 15 can be remotely operated by the flat panel terminal. The battery B is composed of, for example, a lithium ion battery, and supplies power to the distance measuring device 7, the control unit U, the communication unit T, and other parts.

< 2. Structure of distance measuring device

Fig. 4 is a side sectional view of the distance measuring device 7. The distance measuring device 7 configured as a laser range finder has a substantially cylindrical housing 80 extending in the vertical direction when viewed from the outside. The laser light source 71, the collimator lens 72, the light projecting mirror 73, the light receiving lens 74, the light receiving mirror 75, the band pass filter 76, the light receiving unit 77, the rotary housing 78, the motor 79, the substrate 81, the wiring 82, and the disturbance light detection sensor 83 are housed inside the housing 80.

The laser light source 71 is attached to the lower surface of the substrate 81 fixed to the lower surface of the upper end of the frame 80. The laser light source 71 emits a laser beam L1 (projection light) of pulsed light in the infrared region (about 905nm), for example, downward. In the present embodiment, the laser light L1 emitted from the laser light source 71 is a light having a rectangular shape in a plane orthogonal to the optical axis.

The collimator lens 72 is disposed below the laser light source 71. The collimator lens 72 emits the laser light L1 emitted from the laser light source 71 as parallel light downward.

A light projecting mirror 73 is disposed below the collimator lens 72. The light projector 73 is fixed to the rotating frame 78. The rotating frame 78 is fixed to a shaft 79A of the motor 79 and is driven by the motor 79 to rotate around a rotation shaft J. The projector lens 73 is also driven to rotate about the rotation axis J together with the rotation of the rotating frame 78. The projector 73 reflects the laser beam L1 transmitted through the collimator lens 72 on the reflection surface 73a, and projects the reflected laser beam L1 to the outside of the housing 80. Since the projection mirror 73 is rotationally driven as described above, the laser light L1 is emitted while changing the emission direction within 360 degrees around the rotation axis J. At this time, the shape of the laser light L1 in the plane orthogonal to the optical axis is a rectangular shape. Therefore, the shape of the laser beam L1 emitted to the outside of the automated guided vehicle 15 in accordance with the rotation of the rotating frame 78 rotates from one of the vertically long state and the horizontally long state to the other.

The laser light source 71 and the projection mirror 73 constitute a light projection unit that emits laser light L1 as pulse light toward the measurement object.

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

The laser beam L1 reflected by the reflection surface 73a of the light projecting mirror 73 passes through the transmission portion 801 and is emitted from the automated guided vehicle 15 to the outside through the gap S (see fig. 2). In the present embodiment, as shown in fig. 3, the predetermined scanning rotational 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 laser light L1 passes through the transmission portion 801 at least in a range of 270 degrees around the rotation axis J. In the rear region where the transmission portion 801 is not disposed, the laser 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 frame 78 below the light projecting mirror 73. The light receiving lens 74 is fixed to a circumferential side surface of the rotating frame 78. The band pass filter 76 has a sensing multilayer film, and is fixed to the rotating frame 78 at a position below the light receiving mirror 75. The light receiving unit 77 is located below the band pass filter 76, and is fixed to the rotating frame 78.

The laser 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 in this order as incident light L2 and enters the light receiving lens 74. That is, the incident light L2 is a part of the laser light L1 reflected by the object to be measured. The incident light L2 transmitted through the light receiving lens 74 enters the light receiving mirror 75, and is reflected downward by the light receiving mirror 75. The incident light L2 reflected by the light receiving mirror 75 passes through the band-pass filter 76 and is received by the light receiving unit 77. At this time, the band-pass filter 76 transmits only light in the wavelength band of the incident light L2. In the present embodiment, the band-pass filter 76 transmits only light in the infrared region.

The light receiving unit 77 converts the received incident light L2 and the interference light AL into electrical signals by photoelectric conversion. Specifically, the light receiving unit 77 converts the received intensities of the incident light 2 and the interference light AL into a current value.

The disturbance light detection sensor 83 is adjacent to the light receiving unit 77, and detects the intensity of the disturbance light AL. The disturbance light AL is, for example, light (sunlight) from the sun SN or illumination light in a room where the automated guided vehicle 15 moves. Sunlight and illumination light are continuous light. Here, the continuous light means light whose output is substantially constant with respect to time, and the pulsed light means light whose peak value of output repeatedly appears at a predetermined cycle.

The position of the disturbance light detection sensor 83 is not limited to the position adjacent to the light receiving unit 77, and may be a position capable of detecting the intensity of disturbance light. The disturbance light detection sensor 83 may be configured to be able to detect a dc signal of the disturbance light AL, and may be less expensive than the light receiving unit 77.

When the rotating frame 78 is driven to rotate by the motor 79, the light receiving lens 74, the light receiving mirror 75, the band pass filter 76, the light receiving unit 77, and the disturbance light detection sensor 83 are driven to rotate 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 at the scanning rotation angle range θ (═ 270 degrees) is predetermined as a measurement range Rs. When the laser light L1 is emitted in the scanning rotation angle range θ and the laser light L1 is reflected by the measurement object located in the measurement range Rs, the reflected laser light L1 passes through the transmission unit 801 as incident light L2 and enters the light receiving lens 74.

The motor 79 is connected to the substrate 81 through a wiring 82 and is driven to rotate by the passage of current from the substrate 81. The motor 79 rotates the rotating frame 78 at a predetermined rotation speed. For example, the rotating frame 78 is driven to rotate at about 3000 rpm. The wiring 82 is led back in the vertical direction on the rear inner wall of the housing 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.

The distance measuring device 7 includes a laser light emitting unit 701, a laser light receiving unit 702, a distance measuring unit 703, an arithmetic processing unit 704, a data communication interface 705, a driving unit 706, a motor 79, a disturbance light detection sensor 83, and a storage unit 712. The processing unit 704 is connected to a laser light emitting unit 701, a laser light receiving unit 702, a distance measuring unit 703, a data communication interface 705, a driving unit 706, a disturbance light detection sensor 83, and a storage unit 712. The laser light receiving unit 702 is connected to the distance measuring unit 703, and the motor 79 is connected to the driving unit 706.

The laser light emitting unit 701 includes a laser light source 71 (see fig. 4), an LD driver (not shown) that drives the laser light source 71, and the like. The LD driver is mounted on the substrate 81 (see fig. 4).

The laser light receiving unit 702 includes a light receiving unit 77, a dc component blocking unit 707, a current-voltage conversion unit 708, an amplification unit 709, and a comparison unit 710.

The DC component cut-off section 707 is formed of, for example, a capacitor, and cuts off a DC component (DC component) of an electrical signal (current) generated by photoelectric conversion in the light receiving section 77. The current-voltage conversion unit 708 has, for example, a transimpedance amplifier, and converts a current generated by photoelectric conversion in the light receiving unit 77 into a voltage.

The amplifying section 709 has an automatic gain control amplifier, and amplifies an electric signal (voltage). The comparison section 710 has a comparator, compares the level of the electric signal (voltage) of the incident light L2 with a predetermined threshold SL, and binarizes into a high level and a low level. Then, the comparing unit 710 outputs the binarized measurement pulse to the distance measuring unit 703.

The distance measuring unit 703 receives the measurement pulse output from the comparing unit 710. The laser light emitting unit 701 emits laser light L1 using the laser light emission pulse output from the arithmetic processing unit 704 as a trigger. When the emitted laser 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 distance measuring unit 703 receives a reference pulse output together with the laser emission pulse from the arithmetic processing unit 704. The distance measuring unit 703 can acquire the distance to the object OJ by measuring the elapsed time from the rising timing of the reference pulse to the rising timing of the measurement pulse. 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 as measurement data from the distance measuring unit 703. As described above, the distance measuring unit 703 measures the distance to the object OJ based on the comparison result of the comparing unit 710.

The driving unit 706 controls the driving and rotation of the motor 79. The motor 79 is driven to rotate at a predetermined rotational speed by the driving section 706. The arithmetic processing unit 704 outputs a laser emission pulse every time the motor 79 rotates by a predetermined unit angle. For example, the predetermined unit angle is 1 degree. Thus, each time the housing 78 and the projection mirror 73 are rotated by a predetermined unit angle, the laser light emitting unit 701 emits light, and the laser light L1 is emitted.

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

Further, the amount of light received by the laser light receiving unit 702 changes according to the reflectance of light on the object OJ to be measured. For example, when the object OJ to be measured is a relatively dark object and the reflectance of light decreases, the amount of light received decreases, and the rise of the measurement pulse delays. Then, the distance is measured longer by the distance measuring unit 703. In this way, depending on the reflectance of light on the object OJ to be measured, the measured distance may vary even if the distance is substantially the same. Here, if the amount of light received decreases, the length of the measurement pulse is short. In contrast, the arithmetic processing unit 704 corrects the measurement data according to the length of the measurement pulse, thereby improving the distance measurement accuracy. The arithmetic processing unit 704 uses the corrected measurement data when generating the measurement distance data.

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

The arithmetic processing unit 704 further includes a threshold value changing unit 711. The threshold value varying section 711 changes the threshold value SL according to the intensity of the disturbance light AL.

The storage unit 712 stores a table in which the intensity of the disturbance light AL and the threshold SL are associated with each other. For example, in the table, the higher the intensity of the disturbance light AL, the higher the threshold SL.

< 4. action of distance measuring device

In the distance measuring device 7 configured as described above, when the laser light L1 is emitted from the laser light source 71 (see fig. 4), the laser light L1 that becomes parallel light is transmitted through the collimator lens 72 and reflected by the reflection surface 73a of the light projector 73. The laser light L1 reflected by the reflection surface 73a is projected to the outside of the housing 80.

The laser beam L1 reflected by the object OJ becomes an incident light L2, passes through the light receiving lens 74, is reflected by the light receiving mirror 75, passes through the band pass filter 76, and enters the light receiving unit 77. The disturbance light AL also passes through the light receiving lens 74, is reflected by the light receiving mirror 75, passes through the band pass filter 76, and enters the light receiving unit 77. At this time, a part of the disturbance light AL reflected by the light receiving mirror 75 enters the disturbance light detection sensor 83. Thereby, the intensity of the disturbance light AL is detected.

The incident light L2 and the interference light AL incident on the light receiving portion 77 are converted into electrical signals (currents) by the light receiving portion 77. Next, the dc component of the electric signal (current) is cut off by the dc component cut-off section 707. Here, the electric signal (current) of the disturbance light AL as the continuous light corresponds to a direct current component. Therefore, the level of the electric signal (current) corresponding to the disturbance light AL can be significantly reduced by the dc component cut-off section 707.

Next, the current (electric signal) generated by the photoelectric conversion in the light receiving section 77 is converted into a voltage (electric signal) by the current-voltage conversion section 708. Thereafter, the voltage is amplified by the amplifying section 709.

Fig. 6 is a waveform diagram showing the electric signal (voltage) amplified by the amplifying section 709. The vertical axis represents amplitude (unit: mV), and the horizontal axis represents time (unit: ns). A reference pulse (not shown) is input at 0ns, and a measurement pulse Pa is generated at 60-70 ns. In the present embodiment, the threshold SL (low set value SL1) at which the intensity of the disturbance light AL is sufficiently small is set to about 50 mV. That is, the threshold SL is set to about 50mV when the disturbance light AL hardly enters the light receiving unit 77.

As shown in fig. 6, the amplitude of the measuring pulse Pa is approximately 520 mV. On the other hand, when the electric signal (voltage value) is amplified after the dc component of the electric signal (current) is cut off, the amplitude of the electric signal due to the disturbance light is about 180mV on average. Therefore, when the comparison unit 710 compares the level of the electric signal of the incident light L2 with the low set value SL1, not only the incident light L2 but also the disturbance light AL is determined to be at the high level. Therefore, accurate binarization cannot be performed, and the distance measurement by the distance measuring device 7 is not accurate.

In contrast, in the present embodiment, the threshold value variable section 711 changes the threshold value SL according to the intensity of the disturbance light AL. Specifically, the threshold value variable unit 711 increases the threshold value SL from a low set value SL1 (about 50mV) to a high set value SL2 (about 200 mV). Thus, the electric signal of the disturbance light AL and the electric signal of the incident light L2 are clearly determined to be low and high, respectively, and are accurately binarized. Therefore, the distance measuring device 7 can accurately perform distance measurement.

In this case, since the distance measuring device 7 includes the storage unit 712 (see fig. 5) that stores a table in which the intensity of the disturbance light AL and the threshold SL are associated with each other, the threshold value changing unit 711 can easily change the threshold SL.

Fig. 7 is a diagram showing waveforms of electric signals corresponding to incident light L2 and disturbance light AL in the case where a current is converted into a voltage by the current-voltage conversion unit 708 without turning off the dc component. The amplitude corresponding to the dc component D is about 300 mV. In contrast, the amplitude of the peak of the measuring pulse Pa is approximately 510 mV. When the dc component D is cut off, the amplitude of the electric signal of the disturbance light AL is reduced to about 0mV, and the amplitude of the peak of the measurement pulse Pa is also reduced to about 200 mV. Then, the electric signal (voltage) is amplified by the amplifying unit 709 so that the amplitude of the peak of the measurement pulse Pa becomes about 510mV again, and the state shown in fig. 7 is obtained.

When the intensity of the disturbance light AL is sufficiently smaller than the incident light L2, only the dc component D may be cut off by the dc component cutting section 707, and the threshold SL may not be changed by the threshold value changing section 711.

< 5. Electrical Structure of automated guided vehicle

As described above, the electrical configuration on the distance measuring device 7 side is described, but here, the electrical configuration on the automated guided vehicle 15 side is described with reference to fig. 8. Fig. 8 is a block diagram showing an electrical configuration of the automated guided vehicle 15.

The automated guided vehicle 15 includes a distance measuring device 7, a control unit 8, a drive unit 9, a power button 10, and a communication unit T. The control unit 8 is connected to a distance measuring device 7, a drive unit 9, a communication unit T, and a power button 10.

The control unit 8 is provided in the control unit U (see fig. 1). The drive unit 9 includes a motor driver (not shown),

drive motors

4L and 4R, and the like. The motor driver is disposed in the control unit U. The control unit 8 instructs and controls the drive unit 9. The driving unit 9 controls the rotation speed and the 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 in the tablet terminal via the communication section T.

The power button 10 is an operation button for turning on and starting the automated guided vehicle 15.

The control unit 8 receives measured distance data output from the distance measuring device 7. The control unit 8 can create mapping information based on the measured distance data. The map information is information generated for identifying the position of the automated guided vehicle 15 itself, and is generated as position information of a stationary object in the place where the automated guided vehicle 15 travels. For example, when the location where the automated guided vehicle 15 travels is a warehouse, the stationary object is a wall of the warehouse, a rack arranged in the warehouse, or the like.

The mapping information is generated when the automated guided vehicle 15 is manually operated by, for example, a tablet terminal. In this case, an operation signal corresponding to an operation of, for example, a joystick of the tablet terminal is transmitted to the control unit 8 via the communication unit T, and the control unit 8 instructs the drive unit 9 based on the operation signal to control the travel of the automated guided vehicle 15. At this time, the control unit 8 specifies the position of the measurement target object in the place where the automated guided vehicle 15 travels as the mapping information, based on the measured distance data input from the distance measuring device 7 and the position of the automated guided vehicle 15. The position of the automated guided vehicle 15 is determined based on the drive information of the drive unit 9.

The mapping 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 the map information stored in the storage unit 85 in advance, and thereby performs self-position recognition for specifying the position of the automated guided vehicle 15 itself. By performing the self-position recognition, the control unit 8 can perform the automatic travel control of the automated guided vehicle 15 along the predetermined path.

< 6. action of automated guided vehicle

Next, the operation of the automated guided vehicle 15 and the distance measuring device 7 will be described. When the power button 10 is operated, the control unit 8 controls the power from the battery B to be supplied to the parts other than the distance measuring device 7 shown in fig. 5, and starts the automated guided vehicle 15. This starts the traveling of the automated guided vehicle 15. At the same time, the control unit 8 controls the distance measuring device 7 to be activated by supplying electric power from the battery B to the distance measuring device 7.

When the map information is created, the control unit 8 instructs the drive unit 9 to perform the travel control of the automated guided vehicle 15, for example, by a manual operation on the tablet terminal, as described above. When the manual operation of moving the automated guided vehicle straight is performed, the control unit 8 instructs the drive unit 9 to move the automated guided vehicle 15 straight at a predetermined speed and in a predetermined direction (forward or backward). When the manual operation for rotating the automated guided vehicle is performed, the control unit 8 instructs the drive unit 9 to rotate the automated guided vehicle 15 at a predetermined rotation speed, a predetermined rotation angle, and a predetermined rotation direction (right turn or left turn).

When the automated guided vehicle 15 automatically travels while recognizing its position based on the created map information, the control unit 8 automatically instructs the driving unit 9 to move the automated guided vehicle 15 straight or rotate in the same manner as described above.

In the distance measuring device 7, the arithmetic processing unit 704 starts outputting the measured distance data to the automated guided vehicle 15 via the data communication interface 705. When the mapping information is created, the control unit 8 creates the mapping information based on the measured distance data acquired from the distance measuring device 7. Further, when recognizing the self position, the control unit 8 specifies the position of the automated guided vehicle 15 based on comparison between the measured distance data acquired from the distance measuring device 7 and the existing map information.

< 7 > modification of the present embodiment

Fig. 9 is a block diagram showing an electrical configuration of the distance measuring device 7 according to a modification of the present embodiment. The distance measuring device 7 may include a deriving unit 713 instead of the storage unit 712. The deriving unit 713 is connected to the arithmetic processing unit 704, and derives an approximate curve that approximates the relationship between the intensity of the disturbance light AL and the threshold SL. The derived approximate curve is stored in the arithmetic processing unit 704. Thus, the threshold value SL can be derived by interpolation from the intensity of the disturbance light AL, and it is possible to save time and effort to create a table in advance in which the intensity of the disturbance light AL and the threshold value SL are associated with each other. In addition, an increase in the capacity of a storage unit or the like for holding the table can be reduced.

In addition, the threshold value changing unit 711 may change the threshold value SL when the peak value of the incident light L2 binarized by the comparing unit 710 is lower than a predetermined value. For example, the threshold value changing unit 711 raises the threshold value SL, but if binarization is insufficient, the threshold value SL is raised again.

< 8 > action Effect of the present embodiment

According to the distance measuring device 7 of the present embodiment, the distance measuring device 7 includes: a light projecting section that emits laser light L1 (projection light) as pulsed light toward an object OJ to be measured; a disturbance light detection sensor 83 that detects the intensity of disturbance light AL different from the laser light L1; a light receiving unit 77 that receives the interference light AL and the laser light L1 reflected by the measurement object OJ and converts the received light into an electric signal; a comparison section 710 that compares and binarizes the level of the electric signal of the incident light L2 with a predetermined threshold SL; a distance measuring unit 703 for measuring a distance to the object OJ based on the comparison result of the comparing unit 710; and a threshold value variable part 711 that changes the threshold value SL according to the intensity of the disturbance light AL.

Accordingly, even when disturbance light AL (for example, sunlight or illumination light) different from laser light L1 enters light receiving unit 77, threshold SL is changed according to the intensity of disturbance light AL, and the influence of noise caused by disturbance light AL can be reduced. In addition, when the intensity of the disturbance light AL is small, the threshold SL is not set high, and therefore, there is no possibility that the electrical signal of the incident light L2 is evaluated relatively low. Therefore, the distance measuring device 7 can accurately measure the distance to the object OJ to be measured, and the reliability of the distance measuring device can be improved.

The threshold value changing unit 711 increases the threshold value SL as the intensity of the disturbance light AL increases. This can reduce the influence of sunlight or illumination light on the distance measurement by the distance measuring device 7.

The distance measuring device 7 includes a direct current component blocking section 707 for blocking a direct current component (DC component) of an electric signal generated by photoelectric conversion in the light receiving section 77, and an amplifying section 709 for amplifying the electric signal (voltage). This can further remove the influence of noise of the disturbance light AL.

The disturbance light detection sensor 83 is adjacent to the light receiving section 77. This allows the disturbance light detection sensor 83 to more accurately detect the intensity of the disturbance light AL incident on the light receiving unit 77.

The threshold value changing section 711 may change the threshold value SL when the peak value of the incident light L2 binarized by the comparing section 710 is lower than a predetermined value. This makes it possible to more clearly binarize the object, and to more accurately measure the distance to the object OJ.

The distance measuring device 7 includes a storage unit 712 that stores a table in which the intensity of the disturbance light AL and the threshold SL are associated with each other. Thereby, the distance measuring device 7 can easily change the threshold SL.

The distance measuring device 7 may further include a deriving unit 713 that derives an approximate curve that approximates the relationship between the intensity of the disturbance light AL and the threshold SL. Thereby, the distance measuring device 7 can easily change the threshold SL. Further, the threshold value SL corresponding to the intensity of the disturbance light AL can be easily derived by interpolation, and it is possible to save time and effort to create a table in advance in which the intensity of the disturbance light AL and the threshold value SL are associated with each other. In addition, an increase in the capacity of a storage unit or the like for holding the table can be reduced.

The automated guided vehicle 15 (moving body) includes a distance measuring device 7. This makes it possible to easily realize the automated guided vehicle 15 including the distance measuring device 7 capable of improving reliability.

< 9. 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 automated guided vehicle 15 is described as an example of a movable body, but the present invention is not limited to this, and the movable body may be applied to apparatuses other than those for transportation such as a cleaning robot and a monitoring robot. The mobile body may be a passenger car. In this case, the distance measuring device 7 may be mounted on a lower portion of the front surface of the passenger car, and the distance measuring device 7 may measure the distance to an obstacle or the like in front of the passenger car.

In addition, the band pass filter 76 may be omitted from the present embodiment. This can suppress an increase in the pulse width of the electric signal corresponding to the incident light L2, and the distance measuring device 7 can measure the distance more accurately.

Industrial applicability

The present invention can be used, for example, in a distance measuring device and a mobile body including the distance measuring device.

Description of reference numerals:

1 · vehicle body, 1A · base, 1B · gantry part, 2 · baggage rack, 3L, 3R · support part, 4L, 4R · drive motor, 5L, 5R · drive wheel, 6F, 6R · driven wheel, 7 · distance measurement device, 71 · laser source, 72 · collimator lens, 73 · light projector, 73a · reflective surface, 74 · light receiver lens, 75 · light receiver mirror, 76 · bandpass filter, 77 · light receiver part, 78 · rotation frame, 79 · motor, 701 · laser, 702 · laser light, light emitting part 703 · distance measurement part, light receiver part, 705 · rotation frame, power supply part, power, 709 · amplification section, 710 · comparison section, 711 · threshold variable section, 712 · storage section, 713 · derivation section, 80 · frame, 801 · transmission section, 81 · substrate, 82 · wiring, 83 · interference light detection sensor, 8 · control section, 85 · storage section, 9 · drive section, 10 · power button, 15 · unmanned transport vehicle, U · control unit, B · battery, T · communication section, S · gap, measurement range, θ · scanning rotation angle range, J · rotation axis, L · 1 · laser (L · Rs), L · laser light source, SL · polarization, and polarization, D.DC component.

Claims

1. A distance measuring device is characterized in that,

the distance measuring device includes:

a light projecting section that emits projection light as pulsed light toward an object to be measured;

a disturbance light detection sensor that detects intensity of disturbance light different from the projection light;

a light receiving unit that receives the disturbance light and the projection light reflected by the measurement target and converts the disturbance light and the projection light into electrical signals;

a comparison unit which compares the level of the electric signal of the projection light with a predetermined threshold value and binarizes the level;

a distance measuring unit that measures a distance to the measurement target based on a comparison result of the comparing unit; and

and a threshold value changing unit that changes the threshold value according to the intensity of the disturbance light.

2. Distance measuring device according to claim 1,

the threshold value varying unit is configured to increase the threshold value as the intensity of the disturbance light increases.

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

the distance measuring device further includes a dc component blocking unit that blocks a dc component of the electric signal, and an amplifying unit that amplifies the electric signal.

4. The distance measuring apparatus according to any one of claims 1 to 3,

the interference light detection sensor is adjacent to the light receiving unit.

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

the threshold value varying unit varies the threshold value when the peak value of the projection light binarized by the comparing unit is lower than a predetermined value.

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

the distance measuring device includes a storage unit that stores a table in which the intensity of the disturbance light and the threshold are associated with each other.

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

the distance measuring device includes a deriving unit that derives an approximation curve that approximates a relationship between the intensity of the disturbance light and the threshold value.

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

the mobile body includes the distance measuring device according to any one of claims 1 to 7.