JP2024039997A - Distance measuring device and distance measuring method - Google Patents

Abstract

[Problem] To provide a distance measurement device and a distance measurement method using a TOF method, which, when a stain is attached to a window part, measures the stain as an object to be measured, preventing the inability to measure the distance to the object to be measured and preventing the determination that a person is nearby and the shutdown of a nearby manufacturing device, etc. [Solution] The distance measurement device includes a light source, a light receiving unit for outputting a signal according to the intensity of received light, a distance calculation unit for calculating the distance to the object based on the emission time of the detection light and the reception time of the reflected light, and a window part arranged between the light source and the object and capable of transmitting the detection light, and is characterized in that it includes a warning unit for determining that the reflected light is due to stain on the window part and outputting a warning when the distance is equal to or less than a predetermined first threshold, the intensity of received light is equal to or less than a predetermined second threshold, and the intensity of received light is greater than a predetermined third threshold that is smaller than the predetermined second threshold. [Selected Figure] Figure 7

Description

The present invention relates to a distance measuring device and a distance measuring method that measure the distance to an object using a TOF (Time Of Flight) method.

Conventionally, a measuring means for measuring the time from irradiation of a transmitted wave to reception of a reflected wave, an intensity detecting means for detecting the intensity of the reflected wave from a received signal, and a first predetermined number or more of transmitted waves are provided. A vehicle comprising determining means for determining that dirt is attached to the radar means on the condition that the measurement time is shorter than a predetermined measurement time and the intensity of the reflected wave detected by the intensity detection means is equal to or higher than a predetermined intensity. Object recognition devices for use in the art are known. The object recognition device for vehicles can detect the presence of dirt on the surface of the radar device, even if it causes the transmitted waves to propagate inside or scatter the transmitted waves. (For example, see Patent Document 1).

However, even if it is possible to detect the adhesion of dirt as described above (hereinafter referred to as "stain"), for example, the intensity of the reflected wave of the dirt that is generated when the dirt is irradiated with a transmitted wave is limited to a certain level. If the threshold value is exceeded, there is a risk that the stain may be erroneously recognized as an object. For example, the distance to a certain object can be measured by transmitting a laser beam through a window of a case that houses a laser light source, rotation mechanism, light receiving element, etc., and receiving the reflected light. In a scanning type distance measuring device, if the above-mentioned stain is attached to the window and the intensity of the reflected wave from the stain exceeds a predetermined threshold, it is determined that the object is near the distance measuring device. However, there is a risk that the distance to the object that is originally intended to be measured cannot be measured. It is also known to install a distance measuring device around manufacturing equipment in a factory, and to stop the manufacturing equipment when a person approaches the manufacturing equipment to ensure the safety of the person. If used in such a manner, due to the contamination, the distance measuring device may determine that there is a person nearby, and the manufacturing equipment near the distance measuring device may stop, resulting in a decrease in productivity. .

Japanese Patent Application Publication No. 2005-010094

The present invention has been made in view of the above-mentioned problems, and when dirt is attached to the window part, the dirt is measured as an object to be measured, and the distance to the object to be measured is measured. Distance measuring device and distance measuring device using TOF method that can prevent failures and stopping nearby manufacturing equipment etc. due to determining that there is someone nearby. The ultimate purpose is to provide a method.

The present disclosure for solving the above problems is as follows:
a light source that emits pulsed detection light;
a light receiving unit for receiving the reflected light of the detection light from the target object and outputting a signal according to the received light intensity;
a distance calculation unit that calculates a distance to the target object based on an emission time of the detection light and a reception time of the reflected light obtained from a signal output by the light reception unit;
A distance measuring device comprising: a window portion disposed between the light source and the object and capable of transmitting the detection light;
The distance calculated by the distance calculating section is less than or equal to a predetermined first threshold, and the intensity of light received at the light receiving section is less than or equal to a second predetermined threshold, and the intensity of light received at the light receiving section is less than or equal to the predetermined first threshold. Distance measurement characterized by comprising a warning section that determines that the reflected light is due to dirt on the window section and outputs a warning when the reflected light is larger than a predetermined third threshold that is smaller than the second threshold. Including equipment.

When the received light intensity at the light receiving section is less than or equal to a predetermined second threshold value and greater than a predetermined third threshold value, the warning section outputs a warning, thereby preventing the distance of the object to be measured from becoming impossible. It can be prevented. For example, if dirt is attached to the window, the dirt is located between the light source and the object, and the detection light emitted by the light source hits the dirt, there is a risk that the dirt will be mistakenly recognized as the object. By providing a predetermined third threshold value, such misrecognition can be prevented. By outputting the warning from the warning section, the user can understand that the stain has adhered to the window section, and can take measures such as removing the stain.

Further, in the present disclosure, the predetermined third threshold value is equal to or lower than the lowest level of light reception intensity in the light receiving section when an object is placed at a distance equal to or less than the predetermined first threshold value, and the window section The distance measuring device may be characterized in that the received intensity of the reflected light by the window portion is greater than or equal to the received intensity of the reflected light by the window portion when there is no dirt on the window portion. According to this, it is easy to set the predetermined third threshold, and by setting the predetermined third threshold, the target object when the distance calculated by the distance calculation unit is equal to or less than the predetermined first threshold can be prevented from being erroneously determined as soiling.

Further, in the present disclosure, the predetermined third threshold value is a maximum allowable value based on the relationship between the received intensity of the reflected light by the window section and the detection accuracy of the received light intensity. The distance measuring device may be characterized in that the received intensity of the reflected light is equal to or less than the received intensity of the reflected light, and is equal to or greater than the received intensity of the reflected light by the window portion when the window portion is not soiled. According to this, it is easy to set the predetermined third threshold, and by setting the predetermined third threshold, when the distance to the object is less than or equal to the predetermined first threshold, the object is considered to be soiled. Misjudgment can be prevented.

Further, in the present disclosure, the light source emits the detection light along a circumferential direction of the light source, and the warning section is configured to reflect the detection light emitted by the light source in a predetermined direction by the window section. Distance measurement, characterized in that it includes an indicator light that lights up in the predetermined direction when the received light intensity is greater than the predetermined third threshold and less than the predetermined second threshold. It may also be used as a device. According to this, it can be determined that dirt is attached to a location on the window portion located beyond the direction in which the detection light is emitted.

In addition, the present disclosure
a light source that emits pulsed detection light;
a light receiving unit for receiving the reflected light of the detection light from the target object and outputting a signal according to the received light intensity;
a distance calculation unit that calculates a distance to the target object based on an emission time of the detection light and a reception time of the reflected light obtained from a signal output by the light reception unit;
A distance measuring method in a distance measuring device, comprising: a window portion disposed between the light source and the object and capable of transmitting the detection light;
a first comparison step of comparing the distance calculated by the distance calculation unit with a predetermined first threshold;
a second comparison step of comparing the received light intensity at the light receiving section with a predetermined second threshold when the distance calculated by the distance calculation section in the first comparison step is less than or equal to the predetermined first threshold; and,
In the second comparison step, when the received light intensity at the light receiving unit is equal to or less than the predetermined second threshold, the received light intensity is compared with a predetermined third threshold that is smaller than the predetermined second threshold. a third comparison step;
and a warning step of determining that the reflected light is due to contamination of the window portion and outputting a warning if the received light intensity is greater than the predetermined third threshold in the third comparison step. It may also include a distance measuring method characterized by:

According to this, for example, when dirt is attached to the window portion, it is possible to prevent the dirt from being erroneously recognized as an object.

Note that the means for solving the above problems can be used in combination with each other as much as possible.

According to the present invention, in a distance measuring device and a distance measuring method using the TOF method, it is possible to prevent the distance of an object to be measured from becoming impossible to measure, and to stop nearby manufacturing equipment, etc., to improve productivity. It is possible to prevent this from decreasing.

FIGS. 1A and 1B are schematic configuration diagrams of a laser scanner according to an embodiment. FIG. 2 is a schematic diagram of the internal structure of the laser scanner according to the embodiment. FIGS. 3A and 3B are diagrams illustrating types of relationships between signal intensities and distances of window reflected light and object reflected light according to the embodiment. FIG. 3A shows a case where the intensity of the output signal due to the window reflected light is low and the distance to the object is sufficiently long. FIG. 3B shows a case where the intensity of the output signal due to the window reflected light is high to some extent and the distance to the object is sufficiently long. FIG. 4A is a diagram illustrating a type of relationship between the signal strength of the window reflected light and the reflected light from the object and the distance according to the example. FIG. 4A shows a case where the intensity of the output signal due to the window reflected light is high to some extent and the distance to the object is short. FIG. 4B is a diagram illustrating a type of relationship between the signal intensity of window reflected light and distance according to the example. FIG. 4B shows a case where the intensity of the output signal due to the window reflected light is very high. FIG. 5 is a detailed functional block diagram of the control unit according to the embodiment. FIG. 6 is a schematic diagram for explaining a plurality of indicator lights used in conjunction with the warning unit according to the embodiment. FIG. 7 is a flowchart showing the procedure of a distance measuring method using a laser scanner according to an embodiment.

[Application example]
An overview of application examples of the present disclosure will be described below using some drawings. FIGS. 1A and 1B are schematic configuration diagrams of a laser scanner 1 (that is, equivalent to a distance measuring device in the present disclosure), which is an example of a target to which the present disclosure is applied. FIG. 1A is a front view of the laser scanner 1, and FIG. 1B is a plan view. The laser scanner 1 in this application example detects when an obstacle such as a person (hereinafter also referred to as "object") approaches, and performs safety controls such as stopping dangerous manufacturing equipment when it approaches. It is a device for The side surface of the light emitting/receiving section 3 of the laser scanner 1 constitutes a window section, and is made of a material that can transmit the detection light and the light reflected by the object. From the light emitting/receiving section 3, pulsed detection light is emitted onto the scanning surface 3b toward the outside in the radial direction of the light emitting/receiving section 3. This detection light is emitted in a wide angular range while rotating in the circumferential direction of the light emitting/receiving section 3. When a target object is irradiated with this rotating detection light, the presence of the target object is detected by detecting the reflected light, and the distance from the laser scanner 1 is measured.

As shown in FIG. 2, inside the laser scanner 1, a laser light source 33 as a light source that emits detection light and a mirror 32 are provided. A rotary actuator 20 such as a stepping motor is coupled to the laser light source 33 and the mirror 32 via a shaft 31. This rotary actuator 20 rotates based on a command signal from the control section 22. The control section 22 has a hardware configuration equivalent to or a part of a normal PC including a calculation section, a storage section, a communication section (all not shown), and may be included in the sensor unit 2. , may be configured using an external PC. As the rotary actuator 20 rotates, the laser light source 33 and mirror 32 rotate around the rotation axis AX1. At this time, the laser light source 33 emits light intermittently to irradiate the pulsed detection light L1 while rotating it along the scanning surface 3b.

The reflected light that was irradiated onto the object ob and reflected again passes through the window section 3a and enters the light emitting/receiving section 3, is reflected by the mirror 32, passes through the optical system 34, and is then received by the light receiving element 35. be done. The distance to the object ob is calculated from the time of flight (TOF) from when the laser light source 33 irradiates the detection light L1 until the reflected light L3 is detected.

When the pulsed detection light L1 is irradiated from the laser light source 33, a part of it is reflected at the window portion 3a and is detected by the light receiving element 35 as window reflected light L2. Detection of this window reflected light L2 may reduce the accuracy of distance measurement to the object ob.

Here, FIGS. 3A and 3B and FIG. 4A show types of relationships between the signal strength and distance of the window reflected light L2 and the reflected light L3 from the object ob to which the present disclosure is applicable. Note that in FIGS. 3A and 3B and FIGS. 4A and 4B, the horizontal axis is not time but distance from the rotation axis AX1 of the laser scanner 1. In the present disclosure, for example, the distance to the object ob is calculated by multiplying 1/2 of the flight time from the emission of the pulsed detection light L1 to the reception of the reflected light L3 by the speed of light. A similar explanation can be obtained by converting to .

FIG. 3A shows a case where the intensity of the output signal due to the window reflected light L2 is low and the distance to the object ob is sufficiently long. In this case, the window reflected light L2 is not detected because the intensity of the output signal is low in the first place, and it does not affect the output signal due to the reflected light L3 from the object ob, so the window reflected light L2 is ignored. be done. Therefore, the distance to the object ob can be accurately calculated based on the reflected light L3 from the object ob. FIG. 3B shows a case where the intensity of the output signal due to the window reflected light L2 is high to some extent and the distance to the object ob is sufficiently long. In this case, the window reflected light L2 is detected by the light receiving element 35, but since the output signal of the window reflected light L2 and the output signal of the reflected light L3 from the object ob are sufficiently separated, the window reflected light L2 The output signal caused by the reflected light L3 from the object ob does not affect the output signal caused by the reflected light L3 from the object ob. Therefore, in this case as well, the distance to the object ob is accurately calculated based on the reflected light L3 from the object ob.

FIG. 4A shows a case where the intensity of the output signal due to the window reflected light L2 is high to some extent and the distance to the object ob is short. In this case, the output signal from the window reflected light L2 partially overlaps with the output signal from the reflected light L3 from the object ob, which affects the detection of the peak position of the output signal of the reflected light L3 from the object ob. Therefore, in this case, the distance to the object ob is calculated based on the reflected light L3 from the object ob, but the influence of the window reflected light L2 is also taken into account, so compared to the cases shown in FIGS. 3A and B. Then, the object ob
The accuracy of calculating the distance to is reduced.

FIG. 4B shows a type of relationship between the signal strength of the window reflected light L2 and the distance to which the present disclosure is applicable. Here, FIG. 4B shows a case where the intensity of the output signal due to the window reflected light L2 is very high. Therefore, unlike the cases shown in FIGS. 3A and 3B and FIG. 4A, the relationship between the signal strength of the reflected light L3 from the object ob and the distance is not considered. As an example of a case where the intensity of the output signal due to the window reflected light L2 is very high, the window portion 3a is soiled, and the detection light emitted from the laser light source 33 hardly passes through the soiled area. There is a case where the light receiving element 35 receives reflected light due to contamination. Due to this, there is a possibility that the reflected light due to the contamination may be erroneously recognized as the reflected light L3 from the object ob, and it may be incorrectly determined that the object ob is near the laser scanner 1.

In this application example, due to the following aspects, the reflected light due to contamination may be erroneously recognized as the reflected light L3 from the target object ob, and it may be erroneously determined that the target object ob is near the laser scanner 1. It is possible to prevent productivity from decreasing due to stopping of nearby manufacturing equipment etc. due to such judgment. That is, a predetermined second threshold is provided for the intensity of the reflected light L3 from the object ob that the light receiving element 35 receives, and when the intensity of the reflected light L3 from the object ob is equal to or less than the predetermined second threshold, The reflected light received by the light receiving element 35 is determined to be window reflected light L2. Furthermore, a predetermined third threshold value smaller than the predetermined second threshold value is provided for the window reflected light L2, and a warning is issued when the intensity of the window reflected light L2 received by the light receiving element 35 is greater than the predetermined third threshold value. The unit 22d (shown in FIG. 5 below) outputs a warning to notify the user of this fact. Based on the output of this warning, the user can remove in advance the above-mentioned contamination that may cause a misjudgment that the object ob exists. Furthermore, it is also possible to improve the accuracy of calculating the distance to the object ob. Note that the predetermined second threshold value and the predetermined third threshold value will be explained in the flowchart shown in FIG. 7 below.

〔Example〕
Hereinafter, a laser scanner 1 according to an embodiment of the present disclosure and a distance measuring method using the laser scanner 1 will be described in more detail using drawings (including the drawings once explained in the application example above). Note that the laser scanner 1 and the distance measurement method using the laser scanner 1 according to the embodiment of the present disclosure are not limited to the following configuration.

<Device configuration>
Now, returning to the description of FIGS. 1A and 1B. Since the laser scanner 1 according to this embodiment has the same configuration and functions as the laser scanner 1 described in the application example, a detailed explanation of the contents described in the application example will be omitted. Further, in this specification, the same components will be described using the same reference numerals.

As shown in the plan view of FIG. 1B, the laser scanner 1 in this embodiment includes a sensor unit 2 and an I/O unit 4, and is ready for operation by coupling the I/O unit 4 to the sensor unit 2. becomes. The I/O unit 4 is provided with an information terminal 4a for exchanging control signals and detection signals with the outside, and a power supply terminal 4b for supplying power. The distance to the object measured by the laser scanner 1 is outputted through the information terminal 4a.

The sensor unit 2 is equipped with a light emitting/receiving section 3. The light emitting/receiving section 3 has a substantially cylindrical shape, and the side surface has a tapered shape whose diameter decreases toward the bottom. Further, the side surface of the light emitting/receiving section 3 constitutes a window section 3a, which is made of a material that can transmit the detection light and the light reflected by the object. As shown in FIG. 1A, detection light is emitted from the light projecting/receiving section 3 toward the outside in the radial direction of the light projecting/receiving section 3 onto the horizontal scanning surface 3b. As shown in FIG. 1B, this detection light is emitted at predetermined angle intervals in a wide angle range while rotating in the circumferential direction of the light emitting/receiving section 3. When a target object is irradiated with this rotating detection light, the presence of the target object and the distance from the laser scanner 1 are detected by detecting the reflected light. Strictly speaking, the distance from the laser scanner 1 may be the distance from the rotation axis AX1 or the distance from the laser light source 33.

Here, we return to the explanation of FIG. 2. As the rotary actuator 20 rotates, the laser light source 33 and mirror 32 rotate around the rotation axis AX1. At this time, by emitting light from the laser light source 33, it is possible to irradiate the pulsed detection light L1 while rotating it along the scanning surface 3b. Further, the shaft 31 of the rotary actuator 20 is equipped with an encoder 21 to measure the rotation angle and transmit it to the control unit 22. With this encoder 21, it is possible to obtain information about the direction of the object ob, and it is also possible to rotate the laser light source 33 and the mirror 32 at a constant speed at a desired speed.

Further, in the light receiving element 35, the intensity of the reflected light is converted into an electrical signal and transmitted to the measurement control section 22a (shown in FIG. 5 below) in the control section 22. The control unit 22 measures the flight time from when the laser light source 3 emits the pulsed light L1 until the reflected light L3 is detected, and calculates the distance to the object ob from this flight time. Note that the starting point of the flight time (emission time) is the time during which the laser light source 3 emits pulsed light as described above, or the time during which an input signal for light emission is applied to the laser light source 3, optically or electrically. Alternatively, a pseudo object may be provided in the device, and the reception time of the reflected light emitted from the laser light source 3 and reflected from the pseudo object may be set as the emission time. Thereby, error factors such as delays in the driving circuit of the laser light source 3 can be corrected.

FIG. 5 is a detailed functional block diagram of the control unit 22 according to the embodiment. The control unit 22 is provided with a measurement control unit 22a that issues control commands for the above-described light projection/reception and scanning of the detection light, and receives an output signal from the light receiving element 35. Further, a distance calculation section 22b that calculates the distance to the object ob based on the output signal from the light receiving element 35, and an output section 22c such as a monitor that outputs the distance calculated by the distance calculation section 22b are provided.

Further, the distance calculation unit 22b uses a peak value detection unit 220 that detects the peak value of the output signal of the light receiving element 35, and a peak width W of the peak of the output signal of the light receiving element 35 from the peak value of the output signal of the light receiving element 35. A peak width derivation unit 221 is provided for deriving the peak width. Further, there is a falling time detection section 222 that detects the falling time of the peak of the output signal of the light receiving element 35, and a light receiving time calculation section that calculates the light receiving time of reflected light based on the above-mentioned peak width W etc. and the falling time. 224. Furthermore, in addition to the above-described method, a peak time detection unit 223 is provided that detects the peak time from the peak rise time and fall time.

Further, a predetermined first threshold value is provided for the distance calculated by the distance calculation unit 22b. The distance calculated by the distance calculating section 22b is determined by the peak position calculated from the rising position and falling position of the output signal acquired by the light receiving element 35, which is detected by the peak time detecting section 223. If the distance calculated by the distance calculation unit 22b, that is, the distance to the peak position, is less than or equal to the first predetermined threshold, the intensity of the reflected light is compared with the second predetermined threshold, as described above. Note that the predetermined first threshold value will be explained in the flowchart shown in FIG. 7 below. If the intensity of the reflected light is less than or equal to the predetermined second threshold, the reflected light received by the light receiving element 35 is determined to be the window reflected light L2, and the intensity of the window reflected light L2 is compared with a predetermined third threshold. The warning unit 22d outputs a warning to the user when the intensity of the window reflected light L2 is less than or equal to a predetermined second threshold and greater than a predetermined third threshold. As a method of specifically notifying the output of the warning from the warning section 22d, for example, a message indicating that the window section 3a is stained may be displayed on the output section 22c.

FIG. 6 is a schematic diagram for explaining a plurality of indicator lights 5 and 5a used in conjunction with the warning section 22d according to the embodiment. Similar to FIG. 1B, FIG. 6 is a plan view of the laser scanner 1 (indicator light 5 is omitted from illustration in FIG. 1B). The indicator lights 5 and 5a are arranged on the sensor unit 2 at approximately equal intervals along the circumferential direction of the light emitting/receiving section 3. As described above with reference to FIG. 1B, the detection light is emitted from the laser light source 33 at every predetermined angle in a wide angular range while rotating in the circumferential direction of the light emitting/receiving section 3. For example, when the downward dotted line arrow in the orientation shown in FIG. 6 is set as a predetermined reference direction, and the detection light is emitted in a direction rotated by a certain range of angles with respect to the predetermined reference direction, the window reflected light L2 It is assumed that the intensity is less than or equal to a predetermined second threshold and greater than a predetermined third threshold. At this time, as a mode of outputting a warning from the warning unit 22d, for example, an indicator light 5a located in a direction rotated by a certain range of angles with respect to the predetermined reference direction may be turned on. As a result, the user can determine the direction in which the detection light is emitted based on the position of the illuminated indicator light 5a, so that dirt may be attached to a location on the window portion 3a located beyond the direction in which the detection light is emitted. It can be understood that If you can identify the location where the stain is attached, it is easy to remove the stain. Note that the indicator lights 5 and 5a, together with the warning section 22d, correspond to the warning section in the present disclosure.

<Flowchart>
FIG. 7 is a flowchart showing the procedure of a distance measuring method using the laser scanner 1 according to the embodiment. This flow is a flow related to one scan of the laser scanner 1 that is operated by executing a program stored in a storage unit (not shown) in the control unit 22, and is constantly operated by repeatedly operating the flow. It is possible to detect the approach of the object ob.

When this flow is executed, first, in step S101, one scan is started based on a command from the measurement control section 22a of the control section 22. Thereby, the laser scanner 1 starts a scan in which the laser inspection light L1 rotates by a predetermined angle (for example, 270 degrees) on the scanning surface around the rotation axis AX1. In step S102, pulsed detection light L1 is emitted from the laser light source 33 and is projected. Then, in step S103, the light reflected by the object ob or the window portion 3a is received by the light receiving element 35.

Next, in step S104, in the control unit 22, the output signal of the light receiving element 35 in the time period from light emission to light reception is sampled for each distance and converted into digital data. More specifically, the relationship between the output signal from the light receiving element 35 and time is proportionally converted into the relationship between the output signal and distance and converted into digital data. Then, in step S105, the peak time detection unit 223 detects the rising position and falling position of the obtained output signal, and calculates the peak position.

In step S106, it is determined whether the distance to the peak position is greater than a predetermined first threshold. Here, if it is determined that the distance of the peak position is greater than the predetermined first threshold (Yes in step S106), the distance of the object ob is sufficiently far, and the peak of the output signal at the peak position is Since it is determined that this is not the peak of the output signal due to the window reflected light L2 or the peak of the output signal due to the reflected light L3 affected by the window reflected light L2, the process advances to step S108. On the other hand, if it is determined in step S106 that the distance to the peak position is less than or equal to the predetermined first threshold (No in step S106), the peak of the output signal at the peak position is the peak of the output signal due to the window reflected light L2. Alternatively, since it is determined that there is a possibility that the output signal may peak due to the reflected light L3 influenced by the window reflected light L2, the process advances to step S107. Here, step S106 corresponds to the first comparison step in the present disclosure.

In step S108, the distance of the peak position is directly adopted as the distance of the object ob. On the other hand, in step S107, it is determined whether the intensity of the reflected light is greater than a predetermined second threshold. Here, if it is determined that the intensity of the reflected light is greater than the predetermined second threshold (Yes in step S107), it is determined that the obtained reflected light is the reflected light L3 from the object ob. Therefore, the process advances to step S108. On the other hand, if it is determined in step S107 that the intensity of the reflected light is less than or equal to the predetermined second threshold (No in step S107), the obtained reflected light is determined to be the reflected light from the window reflected light L2. Since the determination is made, the process advances to step S109. Here, step S107 corresponds to the second comparison step in the present disclosure.

In step S109, it is determined whether the intensity of the window reflected light L2 is greater than a predetermined third threshold value that is smaller than a predetermined second threshold value. Here, if it is determined that the intensity of the window reflected light L2 is greater than the predetermined third threshold value (Yes in step S109), it is determined that the window portion 3a is stained, for example, and step S110 Proceed to. On the other hand, if it is determined in step S109 that the intensity of the peak of the output signal at the peak position is less than or equal to the predetermined third threshold (No in step S109), the process advances to step S111. Here, step S109 corresponds to the third comparison step in the present disclosure.

Here, the predetermined third threshold value is set according to one of the following two methods. The first method is to set the intensity below the lowest level in the light receiving element 35 when an object (which may be different from the above object ob) is placed at a distance below a predetermined first threshold; In addition, the peak intensity of the window reflected light L2 when there is no dirt on the window portion 3a (the detected light almost completely passes through the window portion 3a and is hardly reflected, so the peak intensity at this time is The intensity is approximately 0) or higher. The second method is to set the intensity of the window reflected light L2 to the maximum allowable intensity based on the relationship between the intensity of the window reflected light L2 and the ranging accuracy (for example, the SN ratio obtained by the light receiving element 35). , and a predetermined third threshold value is set to be greater than or equal to the intensity of the window reflected light L2 when no stain is attached to the window portion 3a. In addition, with either method, by setting a predetermined third threshold value, it is possible to prevent the object ob from being erroneously determined as soiled when the distance to the peak position is less than or equal to the predetermined first threshold value. I can do it.

Returning to the explanation of the flowchart again. In step S110, the warning unit 22d outputs a warning in the manner described in FIG. do. Here, step S110 corresponds to a warning step in the present disclosure. In step S111, it is determined that the light receiving element 35 has received a small amount of window reflected light L2, and the light is ignored.

When the processing in step S110 or step S111 is completed, the process advances to step S112. In step S112, it is determined whether acquisition of distances of all peaks obtained by light projection in step S102 and light reception in step S103 has been completed. Here, if it is determined that the acquisition of the distances of all peaks (all objects ob) has been completed (Yes in step S112), the process advances to step S113. On the other hand, if it is determined that the acquisition of the distances of all peaks is not completed (No in step S112), the process returns to step S106 and the acquisition of the distances of the next peak is executed.

In step S113, it is determined whether all scan angles have been completed. Here, in the laser scanner 1 in this embodiment, light is emitted and received for each scan angle, and in one scan, light is emitted and emitted approximately 500 to 5000 times. The distance to the object ob is acquired for the scan angle θ. Step S113
If it is determined that the acquisition of distances to the object ob at all scan angles has been completed (Yes in step S113), the process proceeds to step S114, and one scan is completed. On the other hand, if it is determined that all scan angles have not been completed (No in step S113), the process returns to step S102, the detection light L1 is emitted from the laser light source 33 again, and the processes from step S102 onwards are repeated. It will be done.

Note that in order to make it possible to compare the constituent features of the present disclosure and the configurations of the embodiments, the constituent features of the present invention are appended with reference numerals in the drawings.
<Additional note 1>
a light source (33) that emits pulsed detection light;
a light receiving unit (35) for receiving the reflected light of the detection light from the target object and outputting a signal according to the received light intensity;
a distance calculation unit (22b) that calculates the distance to the target object based on the emission time of the detection light and the reception time of the reflected light obtained from the signal output by the light reception unit;
A distance measuring device (1) comprising: a window portion (3a) disposed between the light source and the object and capable of transmitting the detection light;
The distance calculated by the distance calculating section is less than or equal to a predetermined first threshold, and the intensity of light received at the light receiving section is less than or equal to a second predetermined threshold, and the intensity of light received at the light receiving section is less than or equal to the predetermined first threshold. The device is characterized by comprising a warning unit (22d) that determines that the reflected light is due to staining of the window portion and outputs a warning when the reflected light is larger than a predetermined third threshold value that is smaller than the second threshold value. , distance measuring device (1).
<Additional note 2>
a light source (33) that emits pulsed detection light;
a light receiving unit (35) for receiving the reflected light of the detection light from the target object and outputting a signal according to the received light intensity;
a distance calculation unit (22b) that calculates the distance to the target object based on the emission time of the detection light and the reception time of the reflected light obtained from the signal output by the light reception unit;
A distance measuring method in a distance measuring device (1) comprising: a window section (3a) disposed between the light source and the object and capable of transmitting the detection light;
a first comparison step (step S106) of comparing the distance calculated by the distance calculation unit with a predetermined first threshold;
a second comparison step of comparing the received light intensity at the light receiving section with a predetermined second threshold when the distance calculated by the distance calculation section in the first comparison step is less than or equal to the predetermined first threshold; (Step S107) and
In the second comparison step, when the received light intensity at the light receiving unit is equal to or less than the predetermined second threshold, the received light intensity is compared with a predetermined third threshold that is smaller than the predetermined second threshold. A third comparison step (step S109),
a warning step (step S110) of determining that the reflected light is due to contamination of the window portion and outputting a warning when the received light intensity is greater than the predetermined third threshold in the third comparison step; A distance measuring method comprising:

1...Laser scanner 2...Sensor unit 3...Light emitting/receiving unit 4...I/O unit 20...Rotary actuator 21...Encoder 22. ...Control section 22a...Measurement control section 22b...Distance calculation section 22c...Output section 22d...Warning section 220...Peak value detection section 221...Peak width derivation section 222...・Fall time detection unit 223...Peak time detection unit 224...Light reception time calculation unit

Claims (5)

a light source that emits pulsed detection light;
a light receiving unit for receiving the reflected light of the detection light from the target object and outputting a signal according to the received light intensity;
a distance calculation unit that calculates a distance to the target object based on an emission time of the detection light and a reception time of the reflected light obtained from a signal output by the light reception unit;
A distance measuring device comprising: a window portion disposed between the light source and the object and capable of transmitting the detection light;
The distance calculated by the distance calculating section is less than or equal to a predetermined first threshold, and the intensity of light received at the light receiving section is less than or equal to a second predetermined threshold, and the intensity of light received at the light receiving section is less than or equal to the predetermined first threshold. Distance measurement characterized by comprising a warning section that determines that the reflected light is due to dirt on the window section and outputs a warning when the reflected light is larger than a predetermined third threshold that is smaller than the second threshold. Device. The predetermined third threshold value is equal to or less than the lowest level of received light intensity in the light receiving section when an object is placed at a distance equal to or less than the predetermined first threshold value, and the third threshold value is equal to The distance measuring device according to claim 1, wherein the received light intensity of the reflected light by the window portion is higher than or equal to the received light intensity. The predetermined third threshold value is less than or equal to the maximum allowable intensity of the light reflected by the window based on the relationship between the intensity of the light received by the window and the detection accuracy of the intensity of the received light. 2. The distance measuring device according to claim 1, wherein the received intensity is greater than or equal to the received light intensity of the reflected light by the window when the window is not soiled. The light source emits the detection light along a circumferential direction of the light source,
The warning unit is configured to detect a case where the received light intensity of the reflected light by the window unit of the detection light emitted by the light source in a predetermined direction is greater than the predetermined third threshold value and less than the predetermined second threshold value. 2. The distance measuring device according to claim 1, further comprising an indicator light that lights up in accordance with the predetermined direction. a light source that emits pulsed detection light;
a light receiving unit for receiving the reflected light of the detection light from the target object and outputting a signal according to the received light intensity;
a distance calculation unit that calculates a distance to the target object based on an emission time of the detection light and a reception time of the reflected light obtained from a signal output by the light reception unit;
A distance measuring method in a distance measuring device, comprising: a window portion disposed between the light source and the object and capable of transmitting the detection light;
a first comparison step of comparing the distance calculated by the distance calculation unit with a predetermined first threshold;
a second comparison step of comparing the received light intensity at the light receiving section with a predetermined second threshold when the distance calculated by the distance calculation section in the first comparison step is less than or equal to the predetermined first threshold; and,
In the second comparison step, when the received light intensity at the light receiving unit is equal to or less than the predetermined second threshold, the received light intensity is compared with a predetermined third threshold that is smaller than the predetermined second threshold. a third comparison step;
and a warning step of determining that the reflected light is due to contamination of the window portion and outputting a warning if the received light intensity is greater than the predetermined third threshold in the third comparison step. A distance measurement method characterized by:

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