JP2017067559A - Distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measuring device that can detect dirt on a cover member as a window member covering an optical member, with simple configurations.SOLUTION: When outgoing pulse lights formed in a hood (2) are passing through the hood (2), an LRF(1) determines a state of abnormality of transmission of the hood (2) from received pulse lights which have passed through a dirt detection region (B), where there are a larger amount of lights generated by reflection of a part of the outgoing pulse lights than in a measurement region (A).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pulse ToF (Time Of Flight) type distance measuring device that measures a distance using an irradiation pulse.

  The distance to the measurement target is calculated based on the time difference between the irradiation pulse being irradiated on the measurement target and the time when the scattered reflected light (received pulse) from the measurement target is received based on the irradiation pulse. A distance measuring device using the pulse ToF method to be calculated has been widely put into practical use.

  By the way, in a pulse ToF type distance measuring device, in order to protect an optical member or the like, a transparent window member is installed in a housing in which the optical member is accommodated, and pulse light is transmitted through the transparent window member. Distance measurement is performed by receiving and emitting light. For this reason, if dirt such as dust or mud adheres to the transparent window member, the reflected light from the dirt affects the light reception pulse, causing an error in the distance measurement value, and in the worst case, the distance measurement becomes impossible. The problem arises.

  Therefore, various techniques for detecting dirt adhering to a transparent window member have been proposed.

  For example, in Patent Document 1, for example, a reflection plate is provided at the position of the extreme end of the scanning angle inside the apparatus, and after a part of the projection light is reflected by this reflection plate, the window surface is irradiated and transmitted. Discloses a technique for determining that dirt is attached when the level of light scattered and reflected and entering the light receiving unit exceeds a threshold value.

  Further, in Patent Document 2, when a foreign matter that adheres to a window portion and suppresses the transmission of laser light adheres larger than the area of the laser light irradiated to the window portion, the reflection reflected by the foreign matter is reflected. The amount of light and the detection time are taken as the amount of foreign matter reflected light and the time of foreign matter reflection. Of the reflected light detected by the light detection means at a time corresponding to the time of foreign matter reflection, the amount of light is lower than the amount of foreign matter reflected. A technique is disclosed in which reflected light that is greater than or equal to a set first threshold value and less than a second threshold value that is set higher than the foreign matter reflected light amount is reflected light from a foreign matter attached to a window.

Japanese Patent Laid-Open No. 9-21108 (released on August 15, 1997) JP 2011-128112 (released on June 30, 2011)

  However, according to Patent Documents 1 and 2 described above, foreign matter (dirt) adhering to the window can be detected, but has the following problems.

  In Patent Document 1, when a foreign object such as a reflector is provided inside the apparatus, a part of the leaked light from the light emitting unit may hit the reflector and stray light entering the light receiving unit may increase. In addition, severe position adjustment of the reflector is necessary.

  Further, in Patent Document 2, in the case of a coaxial optical system, since the stray light and signal light intensity levels and time regions overlap each other, there is no optimum that only the short-distance object is not affected by dirt (foreign matter). It is difficult to set a threshold value. Furthermore, if the foreign material is made of a material with high reflectivity, there is a risk of false detection even if the threshold value is increased. Conversely, if the threshold value is too high, an object with low reflectivity at a short distance cannot be detected. There is a fear.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to measure distance that can accurately detect dirt attached to a cover member as a window member that covers an optical member with a simple configuration. To provide an apparatus.

  In order to solve the above problems, a distance measuring device according to one aspect of the present invention includes a light emitting unit that emits outgoing pulsed light toward the outside while rotating and scanning so that a light emission angle changes, and the light A cover member that covers the emission part and is provided with a transmission region that transmits the emission pulse light in an area where the emission pulse is scanned, and receives reflected light that is generated when the emission pulse light is reflected by the measurement target A light receiving unit that receives the pulsed light; and a distance calculation unit that calculates a distance to the measurement object based on a time difference from when the emitted pulsed light is emitted to when the received pulsed light is received. In the distance measurement device, the transmission region includes a first transmission region, and when the emitted pulsed light is transmitted through the cover member, a generation amount of light generated by reflecting a part of the emitted pulsed light is From the first transmission area Made from more second transmissive region, is characterized in that it further comprises the transmission abnormal state determination unit determines from the second received pulse light transmissive region transmitted through the transmitting abnormal state of the cover member.

  According to one aspect of the present invention, it is possible to accurately detect dirt attached to a cover member as a window member that covers an optical member with a simple configuration.

(A) is sectional drawing which shows the structure of the laser range finder (LRF) concerning Embodiment 1, (b) is a perspective view for demonstrating the distance measurement range. It is a circuit diagram which shows the circuit structure of the said laser range finder (LRF). It is a figure for demonstrating the principle of the stain | pollution | contamination detection by the said laser range finder (LRF). FIG. 3 shows a light emission pulse and a light reception pulse when dirt is detected by the laser range finder (LRF) shown in FIG. 3, (a) shows a light emission pulse and a light reception pulse when the object to be measured is at a long distance, and (b) shows a measurement. It is a wave form diagram which shows the light emission pulse and light reception pulse in case an object exists in a short distance. It is a figure for demonstrating the measurement area | region and dirt detection area | region of the said laser range finder (LRF). (A) is a side view of the said laser range finder (LRF), (b) is a figure which shows the stain | pollution | contamination detection area | region of the cover member of the said laser range finder (LRF) shown to (a). FIG. 6 shows light emission pulses and light reception pulses at the time of detection of dirt by the laser range finder (LRF) shown in FIG. 6, (a) shows waveforms of light emission pulses and light reception pulses that have passed through the measurement area, and (b) shows dirt detection areas. The waveform of the light-emission pulse and the light-reception pulse that have passed through is shown. It is a graph which shows the relationship between the stray light level in the laser range finder (LRF) shown in FIG. 6, and a rotational scanning angle. It is a flowchart which shows the flow of the stain | pollution | contamination determination processing by the laser range finder (LRF) shown in FIG. (A) is a perspective view which shows schematic structure of the laser range finder (LRF) based on Embodiment 2, (b) is a top view for demonstrating the distance measurement range. It is a figure which shows an example which displayed on the host PC the result of the stain | pollution | contamination determination process by the laser range finder (LRF) shown in FIG. (A) is a perspective view which shows schematic structure of the laser range finder (LRF) which concerns on Embodiment 3, (b) is a perspective view for demonstrating the distance measurement range. It is a figure which shows schematic structure of the laser range finder (LRF) which concerns on Embodiment 4. FIG.

Embodiment 1
Embodiments of the present invention will be described below. In the present embodiment, an example of a laser range finder (hereinafter referred to as “LRF”) will be described as the distance measuring device of the present invention.

(Schematic description of LRF1)
FIG. 1A shows a cross section of the LRF 1, and FIG. 1B shows a distance measurement range of the LRF 1.

  The LRF 1 is a ToF (Time Of Fright) type distance measuring device, and measures (calculates) a distance from a time difference between light emission pulse light (emission pulse light) and light reception pulse light (reception pulse light). As shown in FIG. 1A, a light emitting element (light emitting part) 11, an optical member 12, a light receiving element (light receiving part) 13, a motor 14, a shaft 15, a light emitting circuit 16, a light receiving circuit 17, a processor board ( A distance calculation unit 18 and other members (not shown) are included in the hood (cover member) 2 and the housing 3. The casing 3 is provided with a dirt adhesion indicator 20 that indicates that dirt has adhered to the hood 2, that is, an abnormal transmission state has been detected.

  The hood 2 is a substantially cylindrical member made of a resin material that transmits infrared rays and blocks visible light. The hood 2 is a light emission pulse light (bold broken line in the figure: hereinafter referred to as a light emission pulse) and a light reception pulse light. (Thin broken line in the figure: hereinafter referred to as a light receiving pulse), while transmitting light from disturbance light such as sunlight. The hood 2 also has a role of preventing foreign matters from adhering to the internal light emitting element 11, optical member 12, light receiving element 13, motor 14, and the like.

  The light-emitting element 11 is an infrared pulse semiconductor laser, and outputs pulsed light having a pulse width of several ns to several tens ns and an output of several watts as a light emission pulse in accordance with a driving pulse signal input from the outside.

  The optical member 12 is composed of a plurality of mirrors, lenses, light shielding cylinders, and the like, and sends light from the light emitting element 11 to the outside, and guides light from the outside to the light receiving element 13 as a light receiving pulse. Yes.

  Specifically, the optical member 12 includes a rising mirror 12a that reflects the pulsed light (light emitting pulse) output from the light emitting element 11 through the light shielding cylinder 12d to the hood 2 side, and the pulsed light that is raised by the rising mirror 12a. The reflection mirror 12b that reflects to the measurement object (measurement object) 101 existing outside the hood 2 and the pulsed light (light reception pulse) reflected by the measurement object 101 passes through the light shielding cylinder 12e provided in the hood 2. It includes a light receiving lens 12c that is reflected by the reflection mirror 12b toward the light receiving element 13 and collects pulsed light on the light receiving element 13.

  The light receiving element 13 is a PIN photodiode or an avalanche photodiode, and can receive pulsed light (reflected light) that is scattered and reflected by an external measurement object and convert it into a current pulse signal.

  The motor 14 is connected to a part of the optical member 12 including the reflection mirror 12b via the shaft 15, and can rotate the optical member 12 around the Z axis. Thereby, the direction of the light emission pulse light emitted from the light emitting element 11 can be changed, and the horizontal plane can be scanned as shown in FIG. Here, the front-rear direction of the LRF 1 is defined as a Y-axis (Y-Y 'axis), the left-right direction is defined as an X-axis (X-X' axis), and the vertical direction is defined as a Z-axis (Z-Z 'axis).

  The light emitting circuit 16 is mounted with the light emitting element 11 and is a circuit for causing the light emitting element 11 to emit light, and is driven and controlled by the processor board 18.

  The light receiving circuit 17 is a circuit on which the light receiving element 13 is mounted, and a current pulse signal output from the light receiving element 13 is time-to-digital converted into a series of distance data, and is driven and controlled by the processor board 18. Yes.

  The processor board 18 is connected to the light emitting circuit 16 and the light receiving circuit 17 by a harness. Details of the processor board 18 will be described later.

  The LRF 1 having the above configuration is installed, for example, inside an autonomous mobile robot, and is electrically connected to a host PC that controls the robot. The LRF 1 communicates with the host PC, performs measurement according to the control command of the host PC, and transmits measurement data to the host PC.

(LRF1 circuit configuration)
FIG. 2 shows a circuit configuration of the LRF 1, and the components of these circuits are divided and mounted on a plurality of circuit boards.

  The processor board 18 of LRF1 includes a control unit 18a, a TDC calculation unit 18b, a dirt determination unit (transmission abnormality state determination unit) 18c, and a totaling unit 18d shown in FIG.

  The control unit 18 a transmits driving signals to the motor 14, the light emitting circuit 16, and the light receiving circuit 17. Thereby, the light emitting circuit 16 emits pulsed light from the light emitting element 11 as a light emitting pulse. The light emission pulse is output to the outside via the optical member and the hood. At the same time, the motor 14 rotates the optical member 12 to change the emission direction of the light emission pulse in the horizontal plane. That is, the light emitting unit that emits the emitted pulsed light toward the outside while rotating and scanning so as to change the light emitting angle is configured. As a result, as shown in FIG. 1A, a light emission pulse can be projected onto the measurement object 101 in the horizontal plane.

  In addition, LRF1 of this embodiment is designed so that the measurement object 101 in the angle range from -135 deg to +135 deg can be measured with the front as 0 deg.

  A part of the light that reaches the measurement object 101 and is scattered and reflected on the surface reaches the light receiving element 13 via the hood 2 and the optical member 12 as a light receiving pulse, and is converted into a current pulse signal. The light receiving circuit 17 connected to the light receiving element 13 includes a TIA (transimpedance amplifier), an amplifier, and a comparator, and performs current-voltage conversion, amplification, and binarization, respectively. Note that the threshold value input to the comparator is read from the memory inside the control unit 18a.

  The binarized light reception pulse is transmitted to the TDC calculation unit 18b. Similarly, a light emission pulse input to the light emission circuit 16 is also transmitted to the TDC calculation unit 18b.

  The TDC calculation unit 18b converts the time difference between the two binarized signals (light reception pulse and light emission pulse) into a digital value and outputs the digital value to the dirt determination unit 18c and the totalization unit 18d.

  The contamination determination unit 18c determines the contamination of the hood 2 from the received digital value. Details of the dirt determination of the hood 2 by the dirt determination unit 18c will be described later.

  The totalizing unit 18d converts the received digital value into a distance, stores it as data for one rotation of the motor (for one revolution), and outputs it to the host PC in response to a user request.

(Influence of dirt on the hood)
FIG. 3 is a diagram for explaining the influence of foreign matter (dirt) adhering to the hood. FIG. 4 shows a light emission pulse and a light reception pulse when dirt is attached to the hood and when dirt is not attached. FIG. 4A shows a case where the measurement object 101 is at a long distance, and FIG. The light emission pulse and the light reception pulse when the object 101 is at a short distance are shown.

  As described above, the hood is installed to protect internal members (such as optical members and motors), but if foreign matter (dirt) such as dust, sand, or mud adheres during use of the LRF, 3, light scattered and reflected by the foreign matter (broken arrows in the figure) is also returned to the light receiving unit, resulting in an error in measuring the measurement object.

  As shown in FIG. 4 (a), if the measurement object is a long distance, the positions of the light reception pulse due to the dirt and the light reception pulse due to the measurement object are different. is there. However, when the object to be measured is at a short distance close to the hood as shown in FIG. 4B, both pulses overlap each other and cannot be separated from each other.

  The intensity of light returning from an object having a high reflectance is strong, and the pulse width of the received light pulse signal after binarization output through the light receiving circuit is large. On the other hand, the pulse width of the received light pulse signal obtained from an object with low reflectance is narrow. Therefore, in the state as shown in FIG. 4B, there are a state in which the hood is dirty and an object with low reflectance is in a short distance, and a state in which a hood is clean and has a high reflectance is in a short distance. It will be indistinguishable.

  The reflectance of dirt adhering to the measurement object or hood measured by the LRF varies and is distributed over a wide range, so the pulse width of the received light pulse varies greatly depending on the reflectance. For this reason, it is difficult to determine whether the hood is dirty or not using the pulse width as a clue.

  From the above, it can be seen that when measurement is performed with dirt on the hood, it is impossible to remove the measurement error due to dirt afterwards. Therefore, a means for detecting beforehand that the hood is contaminated by some method and a means for notifying the detection result user are required.

  In order to solve the above problem, in the LRF 1 of the present embodiment, a minute “dirt detection region” is provided in a specific region of the hood 2.

(Measurement area and dirt detection area of the hood 2)
FIG. 5 is a diagram for explaining the measurement area and the dirt detection area. 6A is a side view of the LRF 1, and FIG. 6B is a diagram showing a dirt detection region of the hood 2 of the LRF 1 shown in FIG.

  As shown in FIG. 5, the transmission region provided in the region where the emission pulse of the hood 2 is scanned, which transmits the emission pulse light, includes a measurement region (first transmission region) A and the emission pulse light. When passing through the hood 2, it consists of a dirt detection region (second transmission region) B in which the amount of light generated by reflecting a part of the emitted pulsed light is larger than that in the measurement region.

  In the present embodiment, as shown in FIG. 5, the dirt detection area B is about 0.1 mm near both ends of the measurement angle range, that is, around −135 deg and +135 deg when the front is 0 deg and the counterclockwise direction is the positive direction. It is formed with a width of about (corresponding to about 0.25 deg in angle). Thus, by making the width of the dirt detection area B as small as possible and arranging it on both banks of the measurement area A (FIG. 6A), the measurement area A is made as large as possible, and the measurement area A The influence on the signal can be minimized. Further, by providing a plurality of dirt detection regions B (two places in the present embodiment) instead of one, the risk of erroneous detection due to noise and other obstacles can be reduced, and dirt can be detected reliably.

  In order to appropriately measure the distance, the measurement area A is preferably provided continuously in an area having a length corresponding to a light emission angle of 180 degrees or more.

  In this embodiment, the dirt detection area B is formed so that the transmittance of the inner surface of the hood 2 is slightly lower than that of the other area (measurement area A), and the stray light level is slightly higher than that of the other normal areas. ing. Thereby, in the dirt detection region B, when the outgoing pulse light passes through the hood 2, the amount of light generated by reflecting a part of the outgoing pulse light is larger than that in the measurement region A.

  The dirt detection area B is preferably provided adjacent to the measurement area A, and is preferably provided so as to be sandwiched in the measurement area A from both sides.

  In the present embodiment, the change in the transmittance of the dirt detection region is performed by “roughening by laser processing”. A fine dot pattern as shown in FIG. 6B is formed in advance on the inner surface of the hood 2 by laser processing, and the scattering reflectance of the surface is slightly increased only in that portion. By using laser processing, there is an advantage that the transmittance of a minute region on the inner surface of the hood 2 can be controlled with high accuracy and a minute dirt detection region can be formed.

  In addition to the above-described method, the contamination detection region is formed by “mechanical polishing”, “etching with chemicals”, “plating”, “coating agent coating”, “applying a different member”, and “applying the emitted pulse light more than the material of the hood 2”. A method such as “application or sticking of a light-reflecting substance having a high reflectance” is also possible. You may carry out by either of those methods as needed.

(Fouling detection principle of hood 2)
7A shows a measurement region, and FIG. 7B shows a pulse in a dirt detection region.

  FIG. 8 shows the relationship between the stray light level in the LRF 1 and the rotation angle (rotation scanning angle).

  In the LRF 1 in the present embodiment, as shown in FIG. 7B, the measurement is performed so that the stray light level in the dirt detection region B is slightly lower than the measurement threshold in the assembly adjustment process of the LRF 1. A step of adjusting the threshold value (Vth_0) is added.

  In the optical system of LRF1 (such as the optical member 12), the optical design is devised so as to reduce stray light as much as possible, and the light shielding cylinders 12d and 12e are provided to block stray light. Remains. This stray light component has a characteristic that varies depending on the rotation angle, for example, when the size of a slight gap between the light shielding cylinders 12d and 12e and the optical path of the light emission pulse light change according to the rotation angle.

  As described above, the dirt detection region B on the inner surface of the hood 2 has a slightly higher scattering reflectance than the other regions (measurement region A), so that the stray light signal is slightly larger than the other regions. Become.

  If the stain detection area B is not provided and the threshold value is set to a level of V_th1 slightly higher than the stray light level of the measurement area, the fluctuation of the stray light amount according to the rotation angle and its change over time will affect the V_th1. It can exceed the level. In this case, it is very difficult to determine whether the threshold value is exceeded due to fluctuations in the amount of stray light or due to dirt.

  On the other hand, if a dirt detection region B in which the stray light level is intentionally higher than that of the measurement region A is separately provided and the threshold value is set to a level of V_th0 slightly higher than the original stray light level, the fluctuation of stray light in the measurement region A is changed. Since the level is sufficiently higher than the range, even if the stray light component changes with time, this threshold value is not easily exceeded. Only when dirt is attached to the dirt detection area B of the hood 2, the threshold value V_th0 is exceeded as shown in FIG. 7B, and the measurement area A is set as shown in FIG. Since the threshold value V_th0 is not exceeded, it is possible to clearly determine that the hood 2 is dirty rather than a stray light amount variation.

  In the actual assembly adjustment process, the stray light level in the dirt detection region B is actually measured, the threshold value V_th0 is determined as a value slightly larger than that, and the nonvolatile memory existing in the control unit 18a of the LRF1 is stored. Remember me. During the operation of LRF 1, the control unit 18 a reads a value stored in the memory immediately after activation, and sets the value as a threshold value of the comparator in the light receiving circuit 17.

(Food 2 dirt detection operation)
FIG. 9 is a flowchart showing a process flow of the dirt detection operation of the hood 2. In the LRF 1 according to the present embodiment, the dirt determination is performed every time during measurement.

  First, after the power is turned on, the LRF 1 measures the distance by rotating the motor at a constant rotational speed. When the rotation angle reaches one of the two dirt detection regions B, the measurement mode is shifted to the dirt determination mode. Here, the dirt determination mode is started.

  In the dirt determination mode, first, it is determined whether or not there is a signal equal to or greater than a threshold value (S11). Specifically, when the stain determination mode is started, the received light pulse signal measured in the stain detection region B enters the TDC calculation unit 18b, and the calculation result is input to the stain determination unit 18c different from the normal counting unit 18d. Entered. The dirt determination unit 18c checks whether or not there is a signal exceeding the threshold in a time region corresponding to a predetermined position of the hood 2. If there is a signal exceeding the threshold, it is determined that there is dirt. I do.

  If it is determined in S11 that a signal equal to or greater than the threshold value is present (YES), the dirt adhesion flag is set to +1 (S12). On the other hand, if it is determined in S11 that a signal equal to or greater than the threshold does not exist (NO), if the dirt adhesion flag is 1 or more, the flag is set to -1.

  And it is determined whether said flag is more than threshold value N_th (times) (S14). Here, in order to suppress the influence of noise and measurement error, only when there is a signal more than once (N_th times in the present embodiment: actually several times to several tens times) or more (YES), “ It is determined that there is a stain (S15).

  When it is determined that there is dirt, the dirt determination unit 18c blinks the dirt adhesion indicator 20 provided on the housing 3 of the LRF 1 shown in FIG. 1A (S16), and the hood 2 is dirty for the user. Let them know. When it is confirmed that the user removes the dirt on the hood and the received light signal in the dirt detection area falls below the threshold value, the dirt determination unit 18c turns off the dirt adhesion indicator 20.

  On the other hand, if it is determined in S14 that the flag is not equal to or greater than the threshold value N_th, that is, the presence of a signal equal to or greater than the threshold value is not continuously equal to or greater than N times (NO), it is determined that there is no contamination (S17).

  When it is determined that there is no dirt, the dirt judgment unit 18c turns off the dirt adhesion indicator 20 provided on the housing 3 of the LRF 1 shown in FIG. 1A (S18), and the dirt judgment mode. To exit to normal measurement mode.

  Such a stain determination in the stain detection area B may be performed every time during measurement, or may be performed periodically every N rotations or every N minutes (N hours). Furthermore, when the frequency of dirt adhesion is not so high, it is possible to adopt a method of performing only once immediately after startup.

  In the present embodiment, an example in which the dirt detection area B is provided at both ends (two places) of the measurement angle range as shown in FIG. 5 has been described. However, in the following embodiment 2, the dirt detection area B is An example in which three or more are provided will be described.

[Embodiment 2]
Another embodiment of the present invention will be described as follows. For convenience of explanation, members having the same functions as those described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

  FIG. 10A shows a schematic configuration perspective view of the LRF 21, and FIG. 10B is a diagram for explaining a measurement region and a dirt detection region of the LRF 21.

  As shown in FIG. 10A, the LRF 21 according to the present embodiment includes a hood 22 and a housing 23 having substantially the same functions as the hood 2 and the housing 3 of the LRF 1 of the first embodiment. Unlike the hood 2, the hood 22 is provided with a plurality of dirt detection areas B not only at both ends of the measurement area A but also at the center. Specifically, as shown in FIG. 10 (b), dirt detection regions B1 to B7 are provided at seven locations in 45 ° increments.

  When the dirt detection area B is reached during measurement by the measurement area A, the dirt determination process similar to that in the first embodiment is performed. That is, when it is determined that dirt is attached, the dirt adhesion indicator 20 provided on the housing 23 is turned on to prompt the user to clean.

  Furthermore, in this embodiment, as shown in FIG. 11, the result of the dirt determination process in the LRF 21 is transmitted to the host PC together with the measurement data. On the terminal screen of the host PC, it is displayed in which of the dirt detection areas B1 to B7 it is determined that the dirt is attached. Specific locations can be identified.

  Since the user only needs to perform cleaning with reference to information on the presence or absence of dirt displayed on the terminal screen of the host PC and the location thereof, the dirt on the hood 22 can be efficiently removed.

  In the present embodiment, unlike the first embodiment, by providing a large number (three or more) of dirt detection regions B, there is an advantage that a rough place of dirt can be specified. On the other hand, since the dirt determination process is also performed at positions other than both ends of the measurement angle range (front, sideways, etc.), there is a disadvantage that the measurable angle range is reduced accordingly. In order to compensate for this drawback, for example, distance data at the front measurement angle may be obtained by interpolation from the numerical values of the measurement points on both sides.

[Embodiment 3]
Another embodiment of the present invention will be described as follows. For convenience of explanation, members having the same functions as those described in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted.

  12A shows a schematic perspective view of the configuration of the LRF 31, and FIG. 12B is a diagram for explaining a measurement region and a dirt detection region of the LRF 31. FIG.

  The LRF 31 according to this embodiment includes a hood 32 and a housing 33 having substantially the same functions as the hood 2 and the housing 3 of the LRF 1 of the first embodiment, as shown in FIG. As shown in FIG. 12B, three-dimensional scanning is possible. That is, in the first and second embodiments, the scanning is a two-dimensional area indicated by the X-axis direction and the Y-axis direction, but in this embodiment, scanning is further performed in the Z-axis direction. Specifically, the motor that moves a part of the optical member is changed to a biaxial actuator, so that a reciprocating operation in the vertical direction can be performed in addition to the rotating operation around the horizontal plane.

  As described above, by performing measurement while simultaneously performing the rotation operation and the reciprocation operation in the vertical direction, as shown in FIG. 12B, it is possible to measure all of the cylindrical three-dimensional region.

  In the present embodiment, the dirt detection regions B1 and B2 in which the scattering reflectance of the inner surface of the hood is slightly increased are provided at two upper and lower positions as shown in FIG.

  During measurement while changing the scanning direction of the emitted light pulse by operating the biaxial actuator, if the scanning direction reaches the position of the contamination detection area B1 or B2, the contamination determination is performed in the same procedure as in the second embodiment. I do.

  If it is determined that there is dirt, the dirt adhesion indicator 20 provided on the housing 33 of the LRF 31 blinks, and if necessary, information on the presence / absence of dirt and its rough position is transmitted to the host PC (not shown). To do.

  The user can clean the hood by referring to the information on the presence or absence and the location of the dirt displayed on the dirt adhesion indicator or the terminal screen, and remove the dirt on the hood.

  As described above, the LRFs 21, 21, and 31 described in the first to third embodiments are devices for notifying the user that the dirt is attached to the hoods 2, 22, and 32 by the dirt adhesion indicator 20, and It is the user who removes the attached dirt.

  In a fourth embodiment below, an LRF that can automatically remove dirt attached to the hood when it is detected that the dirt has adhered to the hood will be described.

[Embodiment 4]
Another embodiment of the present invention will be described as follows. For convenience of explanation, members having the same functions as those described in the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the present embodiment, an example will be described in which the LRF 1 is installed in an outdoor environment with a relatively large amount of dust and in a remote place where maintenance is difficult. Therefore, in the present embodiment, an example in which the LRF 1 is provided with a function for automatically removing dirt (dirt automatic removing device) will be described. Although not shown, the LRF 1 is connected to a host PC, and the user can remotely operate the host PC.

  The hood 2 of the LRF 1 according to the present embodiment is provided with an antifouling coating, so that it is difficult for dirt to adhere to it. However, if dirt still adheres and the measurement is affected, the host PC Is displayed on the terminal screen, and the automatic dirt removal device is activated.

  FIG. 13 shows an example in which the LRF 1 described in the first embodiment is provided with an automatic dirt removal device for removing dirt attached to the hood 2.

  As shown in FIG. 13, the automatic dirt removal apparatus includes an air compressor 41 for compressing ambient air, a tank 42 for storing compressed air 44, and a plurality of nozzles 43 for blowing compressed air 44 onto the hood surface. Consists of.

  When it is detected that dirt is attached to the hood 2 by the dirt detection operation by the LRF 1, the dirt removal operation by the dirt automatic removal device is executed. During the dirt removal operation, air is compressed by the air compressor 41 and stored in the tank 42, and high-pressure compressed air 44 is blown to the hood 2 by the nozzle 43 at a predetermined timing.

  After the compressed air 44 is blown several times on the hood 2 by the dirt removal operation, the dirt detection operation by the LRF 1 is performed again to check whether the hood 2 is contaminated. That is, it is confirmed whether or not dirt is removed.

  If dirt attached to the hood 2 is not removed even by blowing compressed air 44 several times to several tens of times, information notifying the abnormality of LRF1 is sent to the host PC that receives a signal from LRF1 and used. A person may be notified of an abnormality in LRF1.

  According to the LRF 1 equipped with the automatic dirt removal apparatus having the above-described configuration, most dirt can be automatically removed even if the user does not deal with it manually. For this reason, it is possible to save maintenance work when installed outdoors in a remote place.

  In addition, according to the kind of dirt which can adhere, the structure which has a function which sprays high pressure water / warm water / washing liquid etc. instead of compressed air may be given.

[Example of software implementation]
The control blocks (particularly the control unit 18a, the TDC calculation unit 18b, the dirt determination unit 18c, and the processor substrate 18d constituting the processor board 18) of the LRFs 1, 21, and 31 are logic circuits formed on an integrated circuit (IC chip) or the like. It may be realized by a circuit (hardware) or may be realized by software using a CPU (Central Processing Unit).

  In the latter case, the LRF 1, 21, 31 includes a CPU that executes instructions of a program that is software that realizes each function, and a ROM (Read Only Memory) in which the program and various data are recorded so as to be readable by the computer (or CPU). ) Or a storage device (these are referred to as “recording media”), a RAM (Random Access Memory) for expanding the program, and the like. And the objective of this invention is achieved when a computer (or CPU) reads the said program from the said recording medium and runs it. As the recording medium, a “non-temporary tangible medium” such as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. The program may be supplied to the computer via an arbitrary transmission medium (such as a communication network or a broadcast wave) that can transmit the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

[Summary]
The distance measuring device according to aspect 1 of the present invention includes a light emitting unit (light emitting element 11) that emits outgoing pulsed light toward the outside while rotationally scanning so that the light emitting angle changes, and the light emitting unit (light emitting). A cover member (hood 2, 22, 32), which covers the element 11) and is provided with a transmission region through which the outgoing pulse light is transmitted in a region where the outgoing pulse is scanned, and the outgoing pulse light is a measurement target ( A light receiving unit (light receiving element 13) that receives reflected light generated by being reflected by the measurement object 101) as received pulse light, and a time difference from when the emitted pulse light is emitted until the received pulse light is received. A distance calculation device (LRF1, LRF21, LRF31) including a distance calculation unit (processor board 18) that calculates a distance to the measurement object based on the first transmission region. When the emission pulse light passes through the area (measurement area A) and the cover member (hoods 2, 22, 32), the amount of light generated by reflection of a part of the emission pulse light is the first amount. An abnormal transmission state of the cover member is determined from the received pulsed light that is made up of the second transmission area (dirt detection area B) that is larger than the transmission area (measurement area A) and that has passed through the second transmission area (dirt detection area B) An abnormal transmission state determination unit (dirt determination unit 18c).

  According to the above configuration, the transmission region provided on the cover member that transmits the outgoing pulse light is the first transmission region, and when the outgoing pulse light passes through the cover member, A second transmission region that generates more light than the first transmission region, and the abnormal transmission state of the cover member is determined from the received pulse light transmitted through the second transmission region. .

  Usually, in a transmissive region that transmits outgoing pulsed light provided on a cover member, when foreign matter such as dust adheres as dirt, light (stray light) that is generated by reflection of part of the outgoing pulsed light in the dirty region. ) Is increased.

  For this reason, when dirt adheres to the first transmissive region and the second transmissive region, the amount of stray light generated in both regions increases, but the second transmissive region originally has a larger amount of stray light than the first transmissive region. Therefore, more stray light is generated.

  Therefore, focusing on the amount of stray light generated in the second transmission region, it is possible to accurately detect whether or not dirt has adhered to the transmission region of the cover member, that is, accurately determine the abnormal transmission state of the cover member from the received pulse light. be able to.

  In this way, the optical member can be configured with a simple configuration in which a transmission region for detecting dirt (second transmission region) is provided in the transmission region of the cover member separately from the transmission region for measuring distance (first transmission region). There is an effect that the dirt attached to the cover member as the window member to be covered can be accurately detected.

  In the distance measurement device according to aspect 2 of the present invention, in the aspect 1, the distance calculation unit (processor board 18) is a measurement target in a range of light emission angles corresponding to the first transmission region (measurement region A). The distance to the (measurement object 101) is calculated, and the abnormal transmission state determination unit (processor board 18c) has the cover member in a light emission angle range corresponding to the second transmission region (dirt detection region B). You may make it determine the permeation | transmission abnormal state of (hood 2).

  Clearly divide roles in each region so that normal distance measurement is performed in the first transmission region and normal transmission measurement is not performed in the second transmission region without performing normal distance measurement as in the above configuration. It is preferable to make it.

  In the distance measuring device according to aspect 3 of the present invention, in the above aspect 1 or 2, the second transmission region (dirt detection region B) is provided adjacent to the first transmission region (measurement region A). Also good.

  According to the above configuration, since the second transmission region for detecting dirt is provided adjacent to the first transmission region for measuring the distance, the transmission is performed at a position as close as possible to the first transmission region. Abnormal conditions can be determined. Accordingly, it is possible to detect the contamination of the cover member before stray light is detected in the first transmission region and an error occurs in measurement.

  Here, a part of the linear (annular) region where the light pulse of the cover member is scanned is subjected to a process for increasing the light reflectance, so that the part subjected to this process is the second transmission region, and the other part. Becomes the first transmission region. Therefore, if such a method is used, the second transmission region is necessarily adjacent to the first transmission region.

  The distance measuring device according to aspect 4 of the present invention is the distance measuring device according to any one of the aspects 1 to 3, wherein the second transmission region (dirt detection region B) is from both sides to the first transmission region (measurement region A). It may be provided so as to be sandwiched.

  According to the above configuration, since the second transmission region is sandwiched from both sides of the first transmission region, the cover member becomes dirty before stray light is detected in the first transmission region and an error occurs in measurement. Can be detected more appropriately.

  In the distance measurement device according to aspect 5 of the present invention, in any one of the aspects 1 to 4, the second transmission region (dirt detection region B) may be provided in two or more locations in the transmission region. Good.

  Usually, when dirt adheres to the cover member, the dirt hardly adheres to the entire surface of the transmissive region, and the dirt often adheres to a part of the transmissive region.

  Therefore, as in the above configuration, two or more second transmission regions are provided in the transmission region, so that the position of dirt attached in the transmission region can be accurately detected.

  The distance measuring device according to aspect 6 of the present invention is the distance measuring apparatus according to any one of the aspects 1 to 5, wherein the first transmission region (measurement region A) is provided in two or more locations in the transmission region. At least one of the transmission regions (measurement region A) may be continuously provided in a region having a length corresponding to a light emission angle of 180 degrees or more.

  According to said structure, since the continuous 1st transmission area | region can be enlarged, it is hard to receive to the influence of a 2nd transmission area | region, and can measure a distance appropriately.

  In the distance measurement device according to aspect 7 of the present invention, in any one of the above aspects 1 to 6, the second transmission region (dirt detection region B) is a surface of the cover member (hoods 2, 22, 32). In addition, a light reflective substance having a higher reflectance of the emitted pulsed light than the material of the cover member (hoods 2, 22, 32) may be applied or pasted.

  According to said structure, the 2nd transmission region is formed by apply | coating or sticking a light reflective substance on the surface of a transmission region. Accordingly, the second transmissive region can be formed in the transmissive region by a simple method.

  In the distance measurement device according to aspect 8 of the present invention, in any one of the aspects 1 to 6, the second transmission region (dirt detection region B) is the surface of the cover member (hoods 2, 22, 32). May be roughened.

  According to said structure, the 2nd transmission region is formed by roughening the surface of a transmission region. Accordingly, the second transmissive region can be formed in the transmissive region by a simple method.

  The distance measuring device according to each aspect of the present invention may be realized by a computer. In this case, the distance measuring device is operated on each computer by operating the computer as each unit (software element) included in the distance measuring device. The distance measuring device control program to be realized and a computer-readable recording medium on which the control program is recorded also fall within the scope of the present invention.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

1 LRF (distance measuring device)
2 Hood (cover member)
3 Housing 11 Light emitting element (light emitting part)
12 Optical member 12a Mirror 12b Reflective mirror 12c Light receiving lens 12d Light blocking cylinder 12e Light blocking cylinder 13 Light receiving element (light receiving section)
14 Motor 15 Shaft 16 Light emitting circuit 17 Light receiving circuit 18 Processor board (distance calculation unit)
18a Control unit 18b TDC calculation unit 18c Dirt determination unit (transmission abnormality state determination unit)
18d Totaling unit 20 Adhesion indicator 21 LRF (distance measuring device)
22 Hood (cover member)
23 Housing 31 LRF (Distance Measuring Device)
32 Hood (cover member)
33 Housing 41 Air compressor 42 Tank 43 Nozzle 101 Measurement object (measurement object)
A Measurement area B Dirt detection area

Claims (8)

A light emitting unit that emits outgoing pulsed light toward the outside while rotationally scanning so that the light emission angle changes;
A cover member that covers the light emitting part and is provided with a transmission region that transmits the emitted pulsed light in a region where the emitted pulse is scanned;
A light receiving unit that receives the reflected light generated as a result of reflection of the emitted pulsed light by the measurement object, as received pulsed light;
A distance calculating unit that calculates a distance to the measurement object based on a time difference from when the emitted pulsed light is emitted to when the received pulsed light is received,
The transmission region includes a first transmission region, and when the emitted pulsed light is transmitted through the cover member, the amount of light generated by reflecting a part of the emitted pulsed light is larger than that of the first transmission region. Consisting of a second transmissive region,
The distance measuring apparatus further comprising: a transmission abnormality state determination unit that determines a transmission abnormality state of the cover member from the received pulse light transmitted through the second transmission region. The distance calculation unit calculates a distance to a measurement target in a range of a light emission angle corresponding to the first transmission region,
The distance measurement device according to claim 1, wherein the abnormal transmission state determination unit determines an abnormal transmission state of the cover member in a range of a light emission angle corresponding to the second transmission region.   The distance measuring device according to claim 1, wherein the second transmission region is provided adjacent to the first transmission region.   The distance measuring device according to claim 1, wherein the second transmission region is provided so as to be sandwiched between the first transmission region from both sides.   5. The distance measuring device according to claim 1, wherein the second transmission region is provided at two or more locations in the transmission region. The first transmission region is provided in two or more locations within the transmission region,
6. The distance according to claim 1, wherein at least one of the first transmission regions is continuously provided in a region having a length corresponding to a light emission angle of 180 degrees or more. measuring device.   7. The second transmissive region is formed by applying or sticking a light reflective material having a higher reflectance of the emitted pulsed light than the material of the cover member to the surface of the cover member. The distance measuring device according to any one of the above.   The distance measuring device according to claim 1, wherein the second transmission region has a surface of the cover member roughened.

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