JP5472571B2 - Laser distance measuring apparatus and shielding object detection method thereof - Google Patents

Description

  The present invention relates to a laser distance measuring device that measures the distance of an object by receiving reflected light of a laser beam and a shielding object detection method thereof, and in particular, detects the presence of an object (shielding object) that blocks a laser light irradiation window. The present invention relates to a laser distance measuring device capable of performing the same and a shielding object detection method thereof.

  In general, a laser distance measuring device includes a light projecting unit that emits laser light toward an object, a light receiving unit that receives reflected light from the object, and a signal received from the light projecting unit and the light receiving unit. And a calculation unit for calculating the distance. The light projecting unit and the light receiving unit have a light projecting lens and a light receiving lens for adjusting the size of the laser light, and are stored in the laser radar head. The laser radar head is formed with an irradiation window capable of transmitting laser light and reflected light so that dirt, dust, and the like are not attached to the light projecting lens and the light receiving lens. However, the laser radar head may be disposed outdoors, and dirt, dust, dust, etc. may adhere to the irradiation window. If a flying object with a large area such as newspaper covers the entire irradiation window, it will be impossible to project laser light and receive reflected light. It is. However, when dirt or the like partially covers the irradiation window, it becomes impossible to measure the distance of the target partly, or the projected light quantity decreases and the reflected light of the target object cannot be received. Problems such as misinterpretation of the shielding object with the object occur.

  In order to solve this problem, for example, a method of arranging a scattering plate in a laser radar head (see, for example, Patent Document 1), and a method of arranging a transceiver for detecting dirt in a laser radar head (for example, Patent Document 2). Etc.) have been proposed.

Japanese Patent Laid-Open No. 9-211108 JP-A-10-142335

  However, the laser distance measuring device described in Patent Document 1 has problems such as that the laser beam must be controlled so that the laser beam strikes the scattering plate, and that the entire area of the irradiation window cannot be detected. . In addition, the laser distance measuring device described in Patent Document 2 requires a space for placing the dirt detection transmitter / receiver in the laser radar head, and the cost increases by the amount of the dirt detection transmitter / receiver. There's a problem.

  The present invention has been devised in view of the above-described problems, and a laser distance measuring device capable of detecting the presence of a shielding object that affects distance measurement using a light projecting / receiving device for distance measurement and its shielding object detection. It aims to provide a method.

According to the present invention, there is provided a laser distance measuring device that measures the distance of an object within a measurement range by irradiating laser light through an irradiation window and receiving reflected light from the object. At the same time, a light projecting unit that transmits a light emission synchronization signal, a light receiving unit that receives the reflected light and transmits a light reception signal, and a distance corresponding to a shielding object detection position set between the irradiation window and the measurement range. A light reception signal selection unit that selects a light reception signal of the light source based on the light emission synchronization signal, a signal processing unit for shielding detection that transmits measurement data in association with a light projection condition corresponding to the selected light reception signal, and the measurement A shielding object detection unit that calculates the shape of the object from the data and detects the presence of the shielding object, and the shielding object detection unit includes a width, a height or an area of the shielding object, and a width of the laser beam, Compare the height or area with the shielding. Object is configured to determine whether the obstacle that affect the distance measurement, laser distance measuring device is provided, characterized in that.

The light emitting sync signal and the time measuring unit for calculating a flying light time of the laser beam from the timing of the received light signal, the signal that transmits measurement data including the distance data of the calculated object from the velocity of the flying optical time and light A processing unit , wherein the shielding object detection unit aggregates the measurement data for each of the divided regions obtained by dividing the measurement range into a plurality of regions and the divided regions where the measurement data cannot be totaled. It is configured to output the error area and detect the presence of the shielding object, and the divided area may be an area obtained by dividing the outline of the irradiation window into a size equal to or smaller than the outer shape of the laser beam.

In addition, according to the present invention, there is provided a shielding object detection method for a laser distance measuring device that measures the distance of an object within a measurement range by irradiating laser light through an irradiation window and receiving reflected light from the object. A light reception signal selection step for selecting a light reception signal from a distance corresponding to a shielding object detection position set between the irradiation window and the measurement range, and a light projection condition corresponding to the selected light reception signal A shielding object detection signal processing step for transmitting measurement data; and a shielding object detection step for detecting a shielding object by calculating a shape of the object from the measurement data, wherein the shielding object detection step includes the shielding object. Comparing the width, height, or area of the laser beam with the width, height, or area of the laser beam to determine whether the shield is a shield that affects distance measurement. The method of detecting the shield of the distance measuring device It is subjected.

The shielding object detecting step classifies the measurement data for each divided region obtained by dividing the measurement range into a plurality of regions when calculating a measurement image in the measurement range from the measurement data of the reflected light; includes a summary step of aggregating the measured data for each of the divided regions, and a error region detection step of detecting a divided region which could not be aggregated the measurement data as an error area, the divided region, the The area | region which divided | segmented the outline of the irradiation window into the magnitude | size below the external shape of the said laser beam may be sufficient.

  Here, a counting step for counting the number of detections of the error region and a determination step for determining whether or not the detection number exceeds a threshold value are added, and the shielding object detection step includes the detection number exceeding the threshold value. In this case, the presence of the shielding object may be detected. In addition, a reset process may be added that resets the number of times of error detection when the detection interval of the error area has passed a predetermined time.

For example, the divided area than said number of outline is divided by the size of the laser beam irradiation window, is set in a region divided equally least one greater number both width and height directions. In addition, a divided region changing step for changing the size or boundary of the divided region may be inserted during the repetition of the classification step, the counting step, the error region detection step, and the shielding object detection step.

  According to the laser distance measuring device and the shielding object detection method of the present invention described above, the light receiving signal from the distance corresponding to the shielding object detection position set between the irradiation window and the measurement range is selected to change the shape of the object. By calculating, it is possible to detect an object (shielding object) that stagnates at a position outside the measurement range and shields the irradiation window. In particular, if the shield detection position is set to the position of the irradiation window, an object that is actually blocking the irradiation window can be detected. If the position is set relatively close to the irradiation window, the irradiation window is actually blocked. It is possible to detect the shielding object in a shape close to the size of the object that is present. In the present invention, since a part of the light reception signal in the normal distance measurement process is used, no additional equipment such as a light projecting / receiving device or a scattering plate for detecting an obstacle is required, and the size and cost of the device are increased. These factors can be eliminated, and normal distance measurement processing and control are not hindered.

  Further, according to the above-described laser distance measuring device and the shielding object detection method of the present invention, the measurement data is aggregated for each divided region obtained by dividing the measurement range into a plurality of regions, and the measurement data cannot be aggregated. By outputting the divided area as the error area, the presence of the shielding object can be detected. In the present invention, since the shielding object can be detected using the measurement data used in the normal distance measurement processing, an additional device such as a light projecting / receiving device or a scattering plate for detecting the shielding object is unnecessary. The cause of the increase in size and cost increase can be eliminated, and normal distance measurement processing and control are not hindered.

  In addition, by counting the number of detections of the error area and detecting the presence of the shielding object when the threshold value is exceeded, only the shielding object staying in place by temporarily removing the passing material is effectively detected. be able to. In addition, by resetting the number of error detections after a certain period of time, it is possible to eliminate only temporary error areas and detect only error areas that are temporally continuous, and to detect a shield more effectively. it can. Furthermore, by setting the divided area to be smaller than the outer shape of the laser beam, it is possible to detect a shielding object having a size that causes a problem in distance measurement. In addition, by setting the divided area to the number obtained by dividing the divided area by the size of the laser beam +1, it is possible to detect a shielding object having a size that causes a problem in distance measurement in the minimum divided area. In addition, by inserting a division change step, the size or area of the divided area can be changed periodically or temporarily, and a shield that cannot be detected in a predetermined divided area can be reliably detected. it can.

It is a block diagram which shows 1st embodiment of the laser distance measuring apparatus which concerns on this invention. It is a figure explaining the effect | action of the light reception signal selection part at the time of setting the shield detection position X on the surface of the irradiation window W, (A) shows the relationship between reflected light and a shield, (B) shows the light reception signal. The selection method is shown. It is a figure which shows the output result of a shielding object detection part, (A) is a basic conceptual diagram, (B) is the case where the magnitude | size of a shielding object is larger than a laser beam, (C) is the magnitude | size of a shielding object with a laser beam. (D) shows the case where the size of the shield is partially larger than the laser beam. It is a figure explaining the effect | action of the light reception signal selection part at the time of setting the shielding object detection position X in the position away from the irradiation window W by the distance N, (A) shows the relationship between reflected light and a shielding object, (B ) Shows a method for selecting a received light signal. It is a block diagram which shows 2nd embodiment of the laser distance measuring apparatus which concerns on this invention. It is explanatory drawing which shows the division | segmentation area | region control method of the shielding object detection method employ | adopted by 2nd embodiment of the laser distance measuring apparatus, (A)-(F) is the height Ly of the laser beam of the irradiation window W. When it is larger than the height Wy, (G) and (H) show the case where the size of the laser beam is smaller than the irradiation window W. It is a figure which shows a shield detection flow. It is a figure which shows the 1st modification of a shield detection flow. It is a figure which shows the 2nd modification of a shield detection flow.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. Here, FIG. 1 is a block diagram showing a first embodiment of a laser distance measuring apparatus according to the present invention.

  The laser distance measuring apparatus shown in FIG. 1 is a laser distance measuring apparatus that irradiates laser light L through an irradiation window W and receives reflected light R from an object to measure the distance of the object within the measurement range. The light projecting unit 1 that transmits the light emission synchronization signal S1 simultaneously with the light emission of the laser light L, the light receiving unit 2 that receives the reflected light R and transmits the light reception signal Sr, and the measurement range from the irradiation window W are set. Measurement data by associating a light reception signal selection unit 3 for selecting a light reception signal Sx from a distance corresponding to the detected object detection position X based on the light emission synchronization signal S1 and a light projection condition corresponding to the selected light reception signal Sx. It has the signal processing part 4 for the shielding object detection which transmits Dx, and the shielding object detection part 5 which calculates the shape of an object from the measurement data Dx, and detects presence of a shielding object, It is characterized by the above-mentioned. The light projecting unit 1 and the light receiving unit 2 are accommodated in the laser radar head 6, and an irradiation window W is formed in the laser radar head 6.

  The light projecting unit 1 is a device that emits a laser beam L to irradiate an object within a measurement range. The light projecting unit 1 includes, for example, a laser diode 1a serving as a light source, a light projecting lens 1b that collimates the laser light L, and an LD driver 1c that operates the laser diode 1a. The LD driver 1c operates the laser diode 1a so as to emit the laser beam L based on the trigger signal St from the signal processing unit 11, and simultaneously outputs the pulsed emission synchronization signal S1 at the time measurement unit. Call 12 Note that the light emission synchronization signal Sl may be substituted by the trigger signal St.

  In FIG. 1, the laser light L transmitted through the light projecting lens 1b is scanned in a substantially horizontal direction and a substantially vertical direction by an optical system including a polygon mirror 13 that is rotationally driven and a swing mirror 14 that is rotationally driven. It is configured to be. The polygon mirror 13 has, for example, four sides of a hexahedron mirrored and is configured to be rotated at a high speed by a polygon motor 13a with the center of two opposing surfaces (upper and lower surfaces) as rotation axes. The polygon motor 13a is operated by a motor driver 13b. The swing mirror 14 is constituted by, for example, a plane mirror connected to a side surface of a rotation shaft that is rotated by a swing motor 14a. The swing motor 14a is operated by a motor driver 14b. The motor drivers 13b and 14b are controlled by a signal Sm from the signal processing unit 11 and transmit a light projection condition signal Sc such as a scan angle and a swing angle to the signal processing unit 11. Such an optical system is merely an example, and is not limited to the illustrated configuration.

  The light receiving unit 2 is a device that receives the reflected light R of the laser light L applied to the object. Here, the light projecting unit 1 and the light receiving unit 2 are provided separately so that the light projecting axis and the light receiving axis are shifted from each other, but the light projecting unit 1 and the light receiving axis are aligned with each other. The light receiving unit 2 may be integrally formed. As shown in FIG. 1, the light receiving unit 2 includes, for example, a light receiving lens 2 a that collects the reflected light R, a photoelectric conversion element that receives the collected reflected light R and converts it into a voltage, amplification, compression, And a light receiving unit main body 2b having equipment for performing processing such as decoding. The reflected light R that has passed through the irradiation window W is guided to the light receiving lens 2a through the polygon mirror 13 and the swing mirror 14 in the same manner as the projected laser light L. Then, the light receiving unit main body 2 b that has received the reflected light R transmits a light reception signal Sr converted into a voltage value to the time measuring unit 12. The photoelectric conversion element is a component called a light receiving element, and for example, a photodiode is used.

  For example, the light reception signal selection unit 3 is disposed in the time measurement unit 12 and selects a desired light reception signal Sx from the light reception signal Sr. The time measuring unit 12 has a clock function for measuring time, starts measuring time by receiving the light emission synchronization signal S1, and grasps the time when the light reception signal Sr is received. Therefore, the time measuring unit 12 can measure the time until the projected laser beam L is reflected by the object and received (hereinafter referred to as “light-flying time”). Then, the received light signal Sr within the measurement range is converted into distance data from the flying time and the speed of light in the received light signal processing unit 12a, and the distance data signal Sd is transmitted to the signal processing unit 11. The light reception signal Sr is converted into distance data by, for example, a formula of (speed of light) × (time of flight) / 2. Further, when the shielding object detection position X is set to a certain distance, since the distance is already known, the time Tx for receiving the light reception signal Sx from the distance corresponding to the shielding object detection position X can be obtained in advance. it can. Therefore, time measurement is started by receiving the light emission synchronization signal S1 and the presence or absence of the light reception signal Sr at the predetermined time Tx is confirmed in the light reception signal selection unit 3 from the distance corresponding to the shielding object detection position X. The light reception signal Sx can be selected and picked up. The light reception signal Sx is preferably converted into distance data when transmitted to the signal processing unit 11.

  The shielding object detection signal processing unit 4 is disposed, for example, in the signal processing unit 11, and associates the light reception signal Sx with a light projection condition signal Sc such as a scan angle or a swing angle to measure measurement data for shielding object detection. Send Dx. The signal processing unit 11 includes a distance measurement signal processing unit 11a, and associates the distance data signal Sd from the time measurement unit 12 with the light projection condition signal Sc such as the scan angle and the swing angle to measure the distance. Measurement data Dd is transmitted.

  The shielding object detection unit 5 is disposed, for example, in a control device 15 disposed away from the laser radar head 6, and calculates the shape of the object at the shielding object detection position X from the measurement data Dx. Detect presence. Further, the control device 15 includes an image processing unit 15a that generates an image of an object within the measurement range based on the measurement data Dd, and outputs the measurement result to the output device 16 such as a display, a printer, or an alarm device. It is configured. This control device controls the scan angle and scan speed of the polygon mirror 13, the swing angle and swing speed of the swing mirror 14, the transmission timing of the trigger signal St of the laser beam L, the setting of the shielding object detection position X, etc. The control signal Sh is transmitted to the signal processing unit 11.

  In the first embodiment of the laser distance measuring device described above, the received light signal selection step for selecting the received light signal Sx from the distance corresponding to the shielding object detection position X set between the irradiation window W and the measurement range is selected. A shielding object detection signal processing step for transmitting the measurement data Dx in association with the light projection conditions corresponding to the received light signal Sx, a shielding object detection step for calculating the shape of the object from the measurement data Dx, and detecting the shielding object, A shielding object detection method having the above is adopted.

  Here, the shielding object detection method when the shielding object detection position X is set on the surface of the irradiation window W will be described. FIG. 2 is a diagram for explaining the operation of the received light signal selection unit when the shielding object detection position X is set on the surface of the irradiation window W. FIG. 2A shows the relationship between the reflected light and the shielding object, and FIG. Indicates a method of selecting a received light signal. 3A and 3B are diagrams illustrating output results of the shielding object detection unit, in which FIG. 3A is a basic conceptual diagram, FIG. 3B is a size of the shielding object, and FIG. 3C is a size of the shielding object. Is smaller than the laser beam, (D) shows the case where the size of the shield is partially larger than the laser beam.

  As shown in FIG. 2A, an irradiation window W is installed on the front surface of the laser radar head 6, and the light projecting unit 1 and the light receiving unit 2 are accommodated inside the laser radar head 6. Here, the light projecting unit 1 and the light receiving unit 2 are schematically illustrated. The laser light L1 emitted from the light projecting unit 1 is reflected by an object within the measurement range and received as reflected light R1 by the light receiving unit 2, and is photoelectrically converted by the light receiving unit 2 and output as a light reception signal Sr1. . At this time, when the shielding object 21 such as dirt adheres to the irradiation window W, the laser light L2 irradiated to the shielding object 21 is received by the light receiving unit 2 as reflected light R2 and output as a light reception signal Sr2. . Further, the light projecting unit 1 outputs a light emission synchronization signal S1 simultaneously with the light emission of the laser lights L1 and L2. Here, although the laser beams L1 and L2 are schematically shown by two arrow lines, actually, a part of one laser beam L projected from the projecting unit 1 is actually formed. In some cases, the laser beam L1 and the laser beam L2 may be laser beams irradiated at different timings.

  FIG. 2B shows the relationship between the light emission synchronization signal S1 and the light reception signals Sr1 and Sr2. Since the light reception signal Sr1 is a light reception signal of an object within the measurement range, the light reception signal processing unit 12a of the time measurement unit 12 converts the flying time Δt1 and the speed of light into distance data, and the distance data signal Sd is a signal. It is transmitted to the processing unit 11. The flying time Δt1 is defined by the time required from the light emission timing t0 of the light emission synchronization signal S1 to the light reception time t1 of the light reception signal Sr1 counted.

  Since the shielding object detection position X is now set on the surface of the irradiation window W, the irradiation distance to the irradiation window W depends on the arrangement of the light projecting unit 1 and the light receiving unit 2, the optical characteristics of the polygon mirror 13, the swing mirror 14, and the like. It can be easily determined according to conditions such as the arrangement of the system. At this time, considering that the laser beam L is scanned or swinged, it is preferable to set the irradiation distance to the irradiation window W by a numerical value having a certain width rather than by setting a pinpoint numerical value. For example, the irradiation distance to the irradiation window W is set in a range from the shortest distance to the longest distance when the laser beam L scans the entire surface of the irradiation window W. Then, by dividing this irradiation distance by the speed of light, the detection time Δtw (= Tx) for receiving the reflected light R2 from the irradiation window W can be obtained. The light reception signal selection unit 3 selects and picks up the light reception signal Sr2 included in the detection time Δtw, and transmits it to the signal processing unit 11 as the light reception signal Sx of the shield 21. At this time, similarly to the normal light reception signal Sr1, the selected light reception signal Sr2 (= Sx) is changed to the flight time Δt2 (the time required from the light emission timing t0 of the light emission synchronization signal S1 to the light reception time t2 of the light reception signal Sr2). ) Is preferably converted into distance data. When the irradiation distance to the irradiation window W is fixed to a certain value, the irradiation distance is known in advance, so the light reception signal Sx is converted into distance data without obtaining the flight time Δt2. Alternatively, the distance data may be converted by the signal processing unit 11 or the control device 15.

  The light reception signal Sx of the shield 21 is transmitted to the shield detection unit 5 as measurement data Dx via the shield detection signal processing unit 4. The shielding object detection unit 5 analyzes the measurement data Dx and outputs an image of the shielding object 21 attached to the irradiation window W as shown in FIG. When the detection time Δtw has a predetermined width, the shielding object 21 is output as a 3D image. When the detection time Δtw is set to a pinpoint, the shielding object 21 is output as a 2D image. When the size of the shielding object 21 is larger than the size of the laser beam L as shown in FIG. 3B, it is determined that the shielding object 21 has an influence on the distance measurement. The detected signal (alarm, error display, etc.) is output. Further, as shown in FIG. 3C, when the size of the shielding object 21 is smaller than the size of the laser beam L, it is determined that the shielding object 21 does not affect the distance measurement. Whether or not the shield 21 is larger than the laser beam L may be determined by simply comparing the shapes of the images, and the values of the width Mx, the height My, and the area Ms of the shield 21 may be determined. The numerical values of the width Lx, the height Ly, and the area Ls of the laser light L may be compared to determine numerically. Further, as shown in FIG. 3D, when the shielding object 21 is partially larger than the laser beam L (here, a case where the width Mx of the shielding object 21 is larger than the width Lx of the laser beam L is shown). In other words, since all of the laser light L is not blocked, it is preferable that the distance measurement is not greatly affected, and the shielding object 21 is set so as not to affect the distance measurement.

  Next, a shielding object detection method when the shielding object detection position X is set at a position separated from the irradiation window W by a distance N will be described. FIG. 4 is a diagram for explaining the operation of the received light signal selection unit when the shielding object detection position X is set at a position away from the irradiation window W by the distance N. FIG. 4A shows the relationship between the reflected light and the shielding object. (B) shows a method for selecting a received light signal. In addition, the same code | symbol is attached | subjected to the same component as FIG. 2 (A) and (B), and the overlapping description is abbreviate | omitted.

  As shown in FIG. 2A, when the shielding object detection position X is set on the surface of the irradiation window W, since the irradiation distance is short, the size of the shielding object 21 is output larger than the actual size. There is a case. In this case, although the shielding object 21 does not affect the distance measurement, it is misdiagnosed that the shielding object 21 exists. On the other hand, as shown in FIG. 4A, when the shielding object 21 is attached to the irradiation window, a blind spot area α where the laser beam L does not reach is formed. If the shape of the blind spot area α at the shielding object detection position X is detected, a shape close to the actual size of the shielding object 21 can be output, and the shielding object 21 can be detected more efficiently. . The distance N of the shielding object detection position X is set between the distance from the irradiation window W to the measurement range, and is preferably set to be half the distance from the irradiation window W to the measurement range. This distance N is set so that, for example, the simulated object of the shielding object 21 is attached to the irradiation window W when the laser distance measuring device is adjusted, and the laser beam L is scanned, so that the output image has substantially the same size as the simulated object. The

  Here, as shown in FIG. 4A, the reflected light forming the outer shape of the blind spot area α is R3, and the received light signal is Sr3. FIG. 4B shows the relationship between the light emission synchronization signal S1 and the light reception signals Sr1 and Sr3. The light reception signal Sr1 is processed as described above. The light reception signal Sr3 is basically processed in the same manner as the light reception signal Sr2. However, since the shielding object detection position X is set at a position away from the irradiation window W by the distance N, the light reception time t3 is necessarily larger than the light reception time t2, and the flight time Δt3 is larger than the flight time Δt2. Become. The detection time Δtn is set slightly longer than the detection time Δtw in consideration of the spread of the laser light L, but when the distance N is close to the irradiation window W to such an extent that the spread of the laser light L can be ignored. May be set as Δtn = Δtw. Then, for example, an image as shown in FIG. 3A is output by the same processing as when the shielding object detection position X is set on the surface of the irradiation window W.

  Next, a second embodiment of the laser distance measuring device according to the present invention will be described. Here, FIG. 5 is a block diagram showing a second embodiment of the laser distance measuring apparatus according to the present invention. In addition, the same code | symbol is attached | subjected to the same component as 1st embodiment shown in FIG. 1, and the overlapping description is abbreviate | omitted.

  The laser distance measuring apparatus shown in FIG. 5 is a laser distance measuring apparatus that irradiates laser light L through an irradiation window W and receives reflected light R from the object to measure the distance of the object within the measurement range. The light projecting unit 1 for transmitting the light emission synchronization signal S1 simultaneously with the light emission of the laser light L, the light receiving unit 2 for receiving the reflected light R and transmitting the light reception signal Sr, and the timing of the light emission synchronization signal S1 and the light reception signal Sr. A time measurement unit 52 that calculates a flight time Δt of the laser light L from the signal, a signal processing unit 51 that transmits measurement data D including object distance data calculated from the flight time Δt and the speed of light, and a measurement range Is divided into a plurality of areas, the measurement data D is totaled, and the divided areas where the measurement data D could not be totaled are output as error areas to detect the presence of a shield. And have It is characterized by doing. The light projecting unit 1 and the light receiving unit 2 are accommodated in the laser radar head 6, and an irradiation window W is formed in the laser radar head 6.

  The configuration of the laser radar head 6 is basically the same as that of a commercially available laser distance measuring device, and the present invention is characterized in that the control device 15 is provided with a shielding object detection unit 53. . The calculation of the object distance data may be performed by the time measurement unit 52 or the signal processing unit 51. Therefore, the signal Sd transmitted from the time measuring unit 52 to the signal processing unit 51 may be the flying time Δt or the distance data signal Sd. The measurement data D includes a light projection condition signal Sc such as a scan angle and a swing angle in addition to the distance data. The association between the flight time Δt or the distance data signal Sd and the projection condition signal Sc may be performed by the signal processing unit 51 or may be performed by the control device 15.

  Before describing the detailed operation of the shielding object detection unit 53, a method for forming a divided region of the shielding object detection method employed in the second embodiment of the laser distance measuring device described above will be described. Here, FIG. 6 is an explanatory view showing a method of forming a divided region of the shielding object detection method employed in the second embodiment of the laser distance measuring device, and FIGS. When the height Ly is larger than the height Wy of the irradiation window W, (G) and (H) show the case where the size of the laser beam is smaller than the irradiation window W.

  As shown in FIG. 6A, the laser light L (shaded portion in the figure) has a rectangular shape with a width Lx and a height Ly, and the irradiation window W has a width Wx and a height Wy. Now, it is assumed that the laser beam L and the irradiation window W have a relationship of Lx <Wx, Ly> Wy, Wx = 4Lx. In this case, when the shielding object has a height smaller than the height Wy of the irradiation window W, the laser light L can be irradiated from the gap between the shielding object and the irradiation window W, so that the influence on the distance measurement is small. There is no need to detect the presence of a shield. Therefore, only the shielding object having a height larger than the height Wy of the irradiation window W may be set as the detection target. Further, even if the shielding object has a height larger than the height Wy of the irradiation window W, if the width is smaller than the width Lx of the laser light L, the laser light L from the gap between the shielding object and the laser light L. Can be irradiated and has little effect on distance measurement, and it is not necessary to detect the presence of a shield. Therefore, the minimum width of the shielding object to be detected is equal to the width Lx of the laser light L. In this case, a moment when the laser beam L cannot be irradiated occurs. Therefore, as shown in FIG. 6B, the irradiation window W is divided into four equal parts by a width Ax (= Lx) to form divided regions A1 to A4.

  As shown in FIG. 6B, when the contour of the irradiation window W is divided by the width Lx of the laser light L, for example, as shown in FIG. 6C, it straddles two divided regions A2 and A3. In some cases, the shielding object 21 may be attached, and the shielding object 21 (shaded portion in the figure) cannot be detected. Therefore, as shown in FIG. 6D, the outline of the irradiation window W is divided by a division number (here, five divisions) larger by one than the number divided by the width Lx of the laser light L, and divided regions A1 to A1 are divided. A5 is formed. At this time, the width Ax of the divided regions A1 to A5 has a relationship of Ax <Lx. When divided in this way, the shielding object 21 shown in FIG. 6C completely blocks the divided area A3, so that the shielding object 21 can be detected and the detection capability can be improved.

  Furthermore, in order to improve the detection capability of the shielding object 21, for example, as shown in FIG. 6E, the outline of the irradiation window W may be divided by half the width Lx of the laser light L. . Here, the irradiation window W is divided into eight, and the width Ax = Lx / 2. In this way, when the laser beam L is equally divided by half the width Lx, no matter where the shield 21 is attached, there is a divided region that is always blocked by the shield 21; The shielding object 21 can be detected effectively. Although the case where the laser beam L has a rectangular shape has been described here, even when the laser beam L has a circular shape, an elliptical shape, or the like, the laser beam L is similarly divided according to the length of the diameter in the width direction and the height direction. Regions can be formed.

  Further, as shown in FIG. 6F, the widths Ax of the divided regions are not necessarily equal. In the dividing method shown in FIG. 6 (F), the contour of the irradiation window W is equally divided by a division number (here, five divisions) larger by one than the number divided by the width Lx of the laser light L, The divided areas A1 and A6 obtained by further dividing the above area into half are arranged at both ends, and the remaining four divided areas A2 to A5 are arranged at the center. Here, the divided areas A1 and A6 having a narrow width Ax are arranged at both ends. However, the divided areas having a narrow width Ax may be arranged in a portion where the shield 21 is easily attached.

  In the above description, the case of Ly> Wy has been described. However, even when Ly <Wy, the above-described method of forming the divided regions can be applied in the height direction. Now, it is assumed that the height Ly of the laser light L has a relationship of Wy / 2 <Ly <Wy, as shown in FIG. Here, if the quotient when the height Wy of the irradiation window W is divided by the height Ly of the laser beam L is P and the remainder is Q, in the case shown in FIG. 6G, 1 <P <2. It becomes. At this time, if the quotient P is applied as the number of divisions, the height Ay of the divided region becomes larger than the height Ly of the laser light L, and thus the irradiation window W needs to be divided by the number of divisions of the quotient P + 1. Therefore, here, as shown in FIG. 6 (H), the height Wy of the irradiation window W is divided into two. Further, as described above, if the number of divisions is calculated based on half the height Ly of the laser light L, the detection capability of the shielding object 21 can be further improved. Note that the concept in the case where the size of the irradiation window W is not divisible by the size of the laser light L can be applied to the above-described division in the width direction.

  Next, the operation of the shielding object detection unit 53 will be described with reference to FIGS. Here, FIG. 7 is a diagram illustrating a shielding object detection flow, FIG. 8 is a diagram illustrating a first modification example of the shielding object detection flow, and FIG. 9 is a diagram illustrating a second modification example of the shielding object detection flow. is there.

  The shielding object detection unit 53 of the laser distance measuring apparatus shown in FIG. 5 is configured to process the measurement data D according to the flowchart shown in FIG. 7 and detect the presence of the shielding object. That is, the processing flow of the shielding object detection unit 53 includes an acquisition step 71 for acquiring the measurement data D of the reflected light R and the measurement range when calculating the measurement image within the measurement range from the measurement data D of the reflected light R. A classification process 72 that classifies the measurement data D for each divided area divided into a plurality of areas, a totalization process 73 that totals the measurement data D for each divided area, and the entire irradiation window W once (this is referred to as “1 frame A sum total amount confirmation step 74 for confirming whether or not the measurement data D for a portion) has been summed up, an error region detection step 75 for detecting a divided region where the measurement data D could not be summed as an error region, A counting step 76 that counts the number of detections of the error region; a determination step 77 that determines whether or not the number of detections of the error region exceeds a threshold; a shielding object detection step 78 that detects and outputs the presence of the shielding object; A. The divided areas are divided by the divided area forming method shown in FIG.

  The acquisition step 71 is a step of receiving measurement data D transmitted from the signal processing unit 51. The classification step 72 is a step of distributing the measurement data D acquired in the acquisition step 71 for each divided region. For example, when the irradiation window W is divided into five as shown in FIG. 6D, the measurement data D is classified for each of the divided regions A1 to A5. Note that the measurement data D includes information such as distance data, a scan angle, and a swing angle, and from which position the measurement data D can be analyzed. The counting step is a step of counting the measurement data D classified for each of the divided areas A1 to A5, for example, for each of the divided areas A1 to A5.

  The total amount confirmation step 74 is a step of confirming whether or not the processing from the acquisition step 71 to the totalization step 73 has completed one frame. If the processing for one frame has not been completed (in the case of N), the process of end → start → acquisition process 71 → classification process 72 → aggregation process 73 → aggregation amount confirmation process 74 is repeated. When the processing for one frame is completed (in the case of Y), the process proceeds to an error area detection process 75 which is the next process.

  The error region detection step 75 is a step of detecting whether or not there is a divided region where the measurement data D does not exist as a result of counting the measurement data D in the counting step 73. As described in the description of FIG. 6, when there is a shield larger than the size of the laser beam L, one of the divided areas is completely blocked, and thus the measurement data D is acquired. I can't. Therefore, the divided areas where the measurement data D cannot be aggregated are detected as error areas. Then, only when the error area is detected, the process proceeds to the counting process 76 which is the next process. This counting step 76 is a step of counting the number of times of error area detection. This is because in the case of a temporary shield, the influence on the distance measurement is small, so that only the shield staying for a certain time is detected. Then, in the determination step 77, when the number of error detections exceeds the threshold value (in the case of Y), an output of “there is a shield” is output in the shield detection step 78. The threshold value for the number of error detections can be set arbitrarily. If the number of error detections does not exceed the threshold (in the case of N), the process returns from the end to the start and continues. Note that the counting step 76 and the determining step 77 are not essential steps, and if it is desired to detect even a temporary shield, a flow in which these steps are omitted may be employed.

  Further, as shown in the first modification of FIG. 8, a reset process 81 is added between the counting process 76 and the determination process 77 to reset the number of error detections when the error area detection interval has passed a predetermined time. May be. In general, when a shield adheres to the irradiation window W and stays, error regions should be detected continuously. If the error area is detected intermittently, it may be determined that the error is not based on the same shielding object. Therefore, the error detection count is reset after a certain time has elapsed after counting the error area (0 times). To prevent false detection. In addition, since it is preferable to detect as a shielding object, when a part of shielding object is fluttering by the influence of a wind etc., it is good to set a reset interval to about several seconds-several tens of seconds. In the flowchart shown in FIG. 8, the other processes are the same as those shown in FIG. 7, and thus detailed description thereof is omitted here.

  Further, as shown in the second modification example in FIG. 9, a divided region changing step 92 for changing the size or boundary of the divided region may be inserted between the obtaining step 71 and the classification step 72. In the divided area changing step 92, when the number of measurement frames exceeds a predetermined threshold (for example, 10 frames) by the measurement frame number determination step 91 for determining whether or not the number of measurement frames exceeds the threshold (in the case of Y). Act on. When the number of measurement frames does not exceed the threshold value (in the case of N), the measurement data is aggregated for each divided area based on the preset divided areas by the aggregation step 73. In this divided area changing step 92, if the detection of the shielding object is continued in a certain divided area, there may be a shielding object that is difficult to detect or a shielding object that is rarely detected. In the middle of repeatedly performing the detection step 78, it is preferable to periodically change the size or boundary of the divided regions. For example, divided areas A1 to A5 shown in FIG. 6D are divided into divided areas A1 to A8 shown in FIG. 6E and divided areas A1 to A1 shown in FIG. It is changed to A6, and is changed to the original divided areas A1 to A5 at the next timing. Here, the timing of changing the divided area is counted by the number of measurement frames, but it may be based on the elapsed time (for example, every 5 seconds).

  According to the laser distance measuring apparatus and the shielding object detection method of the present invention described above, a part of the light reception signal Sr or the measurement data D in the normal distance measurement process is used. This eliminates the need for additional equipment such as a scatter plate and a scattering plate, eliminates factors that increase the size and cost of the device, and does not hinder normal distance measurement processing and control, and has an impact on distance measurement. Objects can be detected effectively. In the case of the laser distance measuring device and the shielding object detection method thereof according to the second embodiment, the shielding object can be detected even when the laser distance measuring device has a gate function. Note that the gate function is configured not to receive the reflected light R within a predetermined time after the laser light L is irradiated so as not to receive scattered light such as vapor and dust in a range relatively close to the irradiation window W. It is a function.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Light projection part 1a Laser diode 1b Light projection lens 1c Driver 2 Light reception part 2a Light reception lens 2b Light reception part main body 3 Light reception signal selection part 4 Shielding object detection signal processing part 5 Shielding object detection part 6 Laser radar head 11 Signal processing part 11a Distance measuring signal processing unit 12 Time measuring unit 12a Light receiving signal processing unit 13 Polygon mirror 13a Polygon motor 13b Motor driver 14 Swing mirror 14a Swing motor 14b Motor driver 15 Controller 15a Image processing unit 16 Output device 21 Shielding object 51 Signal processing unit 52 Time Measurement Unit 53 Shielding Object Detection Unit 71 Acquisition Process 72 Classification Process 73 Aggregation Process 74 Aggregation Amount Confirmation Process 75 Error Area Detection Process 76 Counting Process 77 Determination Process 78 Shielding Object Detection Process 81 Reset Process 91 Measurement Frame Number Determination Process 92 Division Area change process

Claims (8)

A laser distance measuring device that irradiates laser light through an irradiation window and receives reflected light from an object to measure the distance of the object within the measurement range,
A light projecting unit for transmitting a light emission synchronization signal simultaneously with the light emission of the laser beam;
A light receiving unit that receives the reflected light and transmits a light reception signal;
A light reception signal selection unit that selects a light reception signal from a distance corresponding to a shielding object detection position set between the irradiation window and the measurement range based on the light emission synchronization signal;
A shielding object detection signal processing unit for transmitting measurement data in association with a light projection condition corresponding to the selected light reception signal;
A shielding object detecting unit for calculating the shape of the object from the measurement data and detecting the presence of the shielding object ,
The shield detection unit compares the width, height, or area of the shield with the width, height, or area of the laser beam to determine whether the shield is a shield that affects distance measurement. Is configured to determine the
A laser distance measuring device. The light emitting sync signal and the time measuring unit for calculating a flying light time of the laser beam from the timing of the received light signal, the signal that transmits measurement data including the distance data of the calculated object from the velocity of the flying optical time and light A processing unit ,
The shielding object detection unit aggregates the measurement data for each divided area obtained by dividing the measurement range into a plurality of areas, and outputs the divided areas where the measurement data could not be aggregated as an error area. Is configured to detect the presence of
The divided region is a region obtained by dividing the outline of the irradiation window into a size equal to or smaller than the outer shape of the laser beam.
The laser distance measuring device according to claim 1 . A shielding distance detection method for a laser distance measuring device that irradiates a laser beam through an irradiation window and receives reflected light from an object to measure the distance of the object within the measurement range,
A light reception signal selection step of selecting a light reception signal from a distance corresponding to a shielding object detection position set between the irradiation window and the measurement range;
A shielding object detection signal processing step for transmitting measurement data in association with a light projection condition corresponding to the selected light reception signal;
A shielding object detecting step of calculating a shape of the object from the measurement data and detecting the shielding object,
The shielding object detecting step compares the width, height, or area of the shielding object with the width, height, or area of the laser beam, and determines whether the shielding object has an influence on distance measurement. To judge,
A shielding object detection method for a laser distance measuring device. The shielding object detecting step classifies the measurement data for each divided region obtained by dividing the measurement range into a plurality of regions when calculating a measurement image in the measurement range from the measurement data of the reflected light; A totaling step of totaling the measurement data for each of the divided regions, and an error region detecting step of detecting a divided region that could not be totaled the measurement data as an error region ,
The divided region is a region obtained by dividing the outline of the irradiation window into a size equal to or smaller than the outer shape of the laser beam.
The shielding object detection method of the laser distance measuring device according to claim 3 characterized by things.   A counting step for counting the number of detections of the error region, and a determination step for determining whether or not the number of detections exceeds a threshold, and the shielding object detection step is performed when the number of detections exceeds the threshold. The method for detecting a shielding object of a laser distance measuring device according to claim 4, wherein the presence of the shielding object is detected.   5. The shielding distance detecting method for a laser distance measuring device according to claim 4, further comprising a resetting step of resetting the number of times of error detection when a predetermined time has passed in the detection interval of the error area.   The divided region is a region that is evenly divided by a number that is larger by at least one in both the width direction and the height direction than the number obtained by dividing the outline of the irradiation window by the size of the laser beam. The shielding object detection method of the laser distance measuring device according to claim 4.   In the middle of repeatedly performing the classification step, the counting step, the error region detection step, and the shielding object detection step, a divided region changing step for changing the size or boundary of the divided region is inserted. The shielding object detection method of the laser distance measuring device according to claim 4.