Distance calculation device

Abstract

To provide a multi-echo type distance calculation device for reducing the amount of data processing and the amount of data transfer and appropriately acquiring object detection information.SOLUTION: A distance calculation device includes: a light emission section for emitting pulsed light in variable directions; a light reception section for receiving reflection light obtained by reflection of pulsed light by an object and generating a light reception signal; a selection section for variably setting each of multiple individual time ranges included in a predetermined time range after emission of the pulsed light, and selecting a peak of at least one signal strength from among peaks of signal strength of the light reception signal in each of the multiple individual time ranges; and a calculation section for calculating distance to the object on the basis of the peak of signal strength selected by the selection section. The selection section sets each of the multiple individual time ranges to a time range according to a current position of the distance calculation device, a captured image captured by an imaging section for imaging scenery around the distance calculation device, or an environment around the distance calculation device specified based on weather around the distance calculation device received from an external server.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a distance calculation device, and more particularly to a multi-echo distance calculation device that uses light or electromagnetic waves. [Background technology]

[0002] Conventionally, devices that recognize objects using light or electromagnetic waves have been used. For example, Patent Document 1 discloses a laser radar device that detects objects in a predetermined area by scanning with a laser beam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-167479 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, a multi-echo laser radar device may be used that detects multiple targets by receiving multiple reflected beams of light generated when a single pulse of light is reflected by the targets, as in the radar device of Patent Document 1. When such a radar device is used, multiple peaks may occur in the received light signal that indicates the intensity of the light received by the radar device after emitting a single pulse of light.

[0005] For example, in Patent Document 1, the reflected light is classified as a primary echo, a secondary optical echo, and a tertiary optical echo in the order of the reflection position where the laser light is reflected from the laser radar device.The document discloses that when there are many primary echoes whose reflection positions are equal to or smaller than a predetermined value, calculations are performed to detect an object by giving priority to the secondary echo and the tertiary echo.

[0006] When using the above-mentioned multi-echo radar device, for example, if multiple objects are concentrated in a similar distance range, there is a possibility that the reflected light from the object that is actually being detected will be ignored, and significant information will be omitted.

[0007] The present invention has been made in consideration of the above-mentioned points, and one of its objects is to provide a multi-echo distance calculation device that can appropriately acquire meaningful object detection information while reducing the amount of data processing and data transfer. [Means for solving the problem]

[0008] The distance calculation device described in claim 1 includes a light emitting unit that emits pulsed light in a variable direction; a light receiving unit that receives light reflected from an object and generates a received light signal; a selection unit that variably sets each of a plurality of individual time ranges included in a predetermined time range after the pulsed light is emitted and selects at least one signal strength peak from among the signal strength peaks of the received light signal in each of the plurality of individual time ranges; and a calculation unit that calculates a distance to the object based on the signal strength peak selected by the selection unit, wherein the selection unit sets each of the plurality of individual time ranges to a time range corresponding to the surrounding environment of the distance calculation device, which is specified based on the current position of the distance calculation device, an image captured by an imaging unit that captures an image of a scenery around the distance calculation device, or weather around the distance calculation device received from an external server. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of an automobile equipped with a distance measuring device according to a first embodiment. [Figure 2] 2 is a diagram illustrating a distance measurement mode of the distance measuring device according to the first embodiment. FIG. [Figure 3] FIG. 2 is a functional block diagram of a controller of the distance measuring device according to the first embodiment. [Figure 4] FIG. 3 is a diagram showing a road information table of the distance measuring device according to the first embodiment. [Figure 5] FIG. 4 is a diagram showing a range pattern table of the distance measuring device according to the first embodiment. [Figure 6] FIG. 4 is a diagram showing a speed-notice distance table of the distance measuring device according to the first embodiment. [Figure 7] 10A and 10B are diagrams showing distance measurement modes when the target distance is "close." [Figure 8] 10 is a diagram showing a distance measurement mode when the target distance is "far."FIG. 11 is a side view of an automobile equipped with a distance measuring device according to a second embodiment. [Figure 9] FIG. 3 is a diagram illustrating an operation control routine of the distance measuring device according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, a detailed description will be given of an embodiment of the present invention, in which a distance measuring device as a distance calculation device is mounted on an automobile as an example of a moving body. [Example]

[0011] 1 is a perspective view of an automobile M equipped with a distance measuring device 10 as a distance calculation device according to Example 1. In Example 1, a case will be described in which the distance measuring device 10 is attached to the front bumper of the automobile M.

[0012] The distance measuring device 10 is a laser distance measuring device that measures distance by emitting laser light LL, which is a pulsed laser (hereinafter also referred to as pulsed light), and receiving light reflected from an object that reflects the emitted pulsed light. The distance measuring device 10 is mounted in the center of the front bumper at the front end of the automobile M. The distance measuring device 10 is configured to be able to emit laser light LL from a laser exit / entrance window AP toward the front of the automobile M. The distance measuring device 10 is also configured to be able to receive reflected light RL, which is generated when the laser light LL is reflected by an object (not shown) located in front of the automobile M, via the laser exit / entrance window AP.

[0013] In the following example, when the distance measuring device 10 emits a laser beam LL, which is a single pulse of light, it detects each of multiple objects and calculates the distance to each of the objects based on the peaks of the signal intensity of the multiple reflected lights in a received light signal that includes multiple peaks due to the multiple reflected lights RL. That is, in the following example, the distance measuring device 10 is a so-called multi-echo type distance measuring device. In addition, in the following description, the distance measuring device 10 detects objects using five signal peaks in a received signal when it emits a laser beam LL, which is a single pulse of light.

[0014] FIG. 2 is a diagram showing the manner in which distance measurement is performed by the distance measuring device 10. FIG. 2 shows a top view of the automobile M and its surroundings during distance measurement, as well as a light detection signal WF including a peak due to reflected light RL. In FIG. 2, the laser light LL is indicated by diagonal lines. FIG. 2 also shows a bicycle BI, a pedestrian WM, and three automobiles M1, M2, and M3 as objects in the vicinity of the automobile M.

[0015] The distance measuring device 10 intermittently emits pulsed laser light LL ahead of the automobile M. The distance measuring device 10 emits one laser light LL, performs light detection during the period until the next laser light LL is emitted, and generates a light detection signal based on the light detection. The distance measuring device 10 selects a peak due to reflected light RL from the light detection signal and calculates the distance to the target based on the time the peak occurred.

[0016] The distance measuring device 10 divides the area irradiated with the laser light LL into a plurality of distance measuring areas based on the distance from the distance measuring device 10, detects an object in each divided area, and measures the distance to the object. In this embodiment, the area in front of the automobile M is divided into distance measuring areas AR1, AR2, AR3, AR4, and AR5, starting from the area closest to the distance measuring device 10 provided at the front end of the automobile M. In Figure 2 and similar figures below, the boundaries of the distance measuring areas AR1-AR5 are indicated by dashed two-dot lines.

[0017] The distance measuring device 10 sets a time range in which reflected light RL from an object in each region is expected to arrive after emitting laser light LL, based on the emission time. Then, one peak of the light detection signal, e.g., the peak with the largest signal value, is selected for each of the set time ranges, and the object is detected based on the selected peak to calculate the distance. In this embodiment, the time ranges in which reflected light RL from objects in regions AR1, AR2, AR3, AR4, and AR5 reaches the distance measuring device 10 are designated time ranges TR1, TR2, TR3, TR4, and TR5, respectively.

[0018] Time range TR1 is from time t1 to time t2, time range TR2 is from time t2 to time t3, time range TR1 is from time t1 to time t2, time range TR2 is from time t2 to time t3, time range TR3 is from time t3 to time t4, time range TR4 is from time t4 to time t5, and time range TR5 is after time t5.

[0019] 2, the peak due to reflected light RL from bicycle BI is P1, the peak due to reflected light RL from automobile M1 is P2, the peak due to reflected light RL from pedestrian WM is P3, the peak due to reflected light RL from automobile M2 is P4, and the peak due to reflected light RL from automobile M3 is P5. Other slightly smaller peaks PN are, for example, reflected light generated when laser light LL is reflected by rain, snow, other floating objects, etc., ambient light such as the headlights of oncoming vehicles, or signal noise.

[0020] In reality, the intensity of the photodetection signal varies depending on the distance to the object reflecting the laser light LL and the reflectivity of the object. Therefore, for example, a peak of the photodetection signal detected due to a nearby floating object may be greater than a peak of the photodetection signal detected due to a distant vehicle. However, for simplicity of explanation, peaks P1, P2, P3, P4, and P5 of the photodetection signal caused by the objects present in each region, namely, a bicycle BI, a pedestrian WM, and three vehicles M1, M2, and M3, are emphasized in FIG. 2 .

[0021] Similarly, in FIGS. 7 and 8 described later, peaks P1, P2, P3, P4, and P5 of the photodetection signals caused by the objects present in each region are emphasized.

[0022] 2, the maximum peaks in each time range TR1-TR5 are peak P1 due to bicycle BI, peak P2 due to car M1, peak P3 due to pedestrian WM, peak P4 due to car M2, and peak P5 due to car M3. Therefore, if an object is detected using the maximum peak in each time range as described above and the distance to the object is calculated, the distance to each object is calculated based on each of peaks P1-P5.

[0023] 2, only a portion of the area AR5 is shown, but the area AR5 ends at a predetermined distance from the automobile M. Therefore, the time range TR5 also ends at a predetermined time after t5.

[0024] [Configuration of distance measuring device] 3 is a diagram showing the configuration of the distance measuring device 10. The laser emitting and receiving unit 20 has a light emitting unit 21 that emits laser light LL and a light receiving unit 23 that receives light including reflected light RL generated when the laser light LL is reflected by an object (not shown) and is capable of outputting a light receiving signal that changes depending on the intensity of the received light. As described above, the laser light LL and reflected light RL are emitted and received through the laser exit / entrance window AP. That is, the light emitting unit 21 can emit the laser light LL through the laser exit / entrance window AP, and the light receiving unit 23 can receive the reflected light RL through the laser exit / entrance window AP.

[0025] The light receiving unit 23 may be composed of, for example, a laser element that emits laser light LL and a deflecting element such as a MEMS mirror that variably polarizes the laser light LL emitted by the laser element. Alternatively, the light receiving unit 23 may be composed of a light receiving element that can receive the reflected light RL and generate an electrical signal.

[0026] The controller 30 is a device in which a mass storage device 33 , a control unit 35 , an emission control unit 36 ​​, an input unit 37 , and a data communication unit 38 cooperate with each other via a system bus 31 , for example.

[0027] The mass storage device 33 is configured with, for example, a hard disk drive, a solid state drive (SSD), a flash memory, etc., and stores various programs such as an operating system and terminal software. Note that the various programs may be obtained, for example, from another server device or the like via a network, or may be recorded on a recording medium and read via various drive devices.

[0028] In other words, the various programs stored in the large-capacity storage device 33 (including programs for controlling the laser emitting / receiving unit 20 and for executing processes for calculating the distance to the target object) can be transmitted via a network, and can also be recorded on a computer-readable recording medium and transferred.

[0029] A map information database (map information DB) 33A is constructed in the mass storage device 33. The map information database 33A is a database that holds map information including road maps. The map information database 33A holds information indicating the road conditions and the like for each road or road section, along with the road maps.

[0030] Fig. 4 is an example of a road information table TB1 included in the map information database 33A. As shown in Fig. 4, the road information table TB1 includes, for example, road names (general road names, expressway names), kilometer post information for the start and end points of road sections, road attributes of the road sections, and attention distances, which are distances at which it is expected that there will be many notable objects on the roads, i.e., objects whose distances should be detected and calculated. The attention distance can also be said to be a distance at which attention should be paid. In the road information table TB1, for example, the attention distances are listed in descending order as "close," "near," "medium," "fairly far," and "far."

[0031] In the mass storage device 33, a range pattern database (range pattern DB) 33B is constructed, which stores information on the relationship between the speed of the automobile M and the target distance, or the setting patterns of the individual distance ranges or time ranges.

[0032] 5 shows an example of distance range pattern table TB2 included in range pattern database 33B. Distance range pattern table TB2 is a table intended for the case where distance is calculated using five peaks from the received signal, as explained above.

[0033] 5, range pattern table TB2 shows, for example, for each pattern, the individual distance ranges of the five ranging areas AR1-AR5 described above, in order from the range closest to automobile M. In range pattern table TB2, range patterns 1-5 correspond to the target distances of road information table TB1: "close," "near," "medium," "fairly far," and "far," respectively.

[0034] The distance measuring device 10 converts the distance ranges shown in the range pattern table TB2 into time ranges in which reflected light RL reflected from an object within the distance range is received, and sets and uses the converted time ranges as individual time ranges. This conversion may be performed, for example, by dividing twice the distance shown in the range pattern table TB2 by the speed of light. Alternatively, a table showing time ranges corresponding to the distance ranges shown in the range pattern table TB2, such as the above-mentioned t1-t5, may be stored in advance, and the individual time ranges may be set using this table.

[0035] As shown in range pattern table TB2, all distance ranges or corresponding time ranges do not have to be evenly allocated in one pattern. Also, the start point of the distance range of range 1 does not have to be 0 m. In other words, individual distance ranges or individual time ranges may be set so that object detection and distance calculation are not performed for a certain distance from automobile M.

[0036] In addition, in TB2, the end of range 5 (AR5) is set to 100 m as an example, but the end distance is not limited to this. For example, the end may be the end position of an area where an object can be detected and the distance can be calculated using pulsed light 1. The time range corresponding to range 5 (AR5) ends at the time when the reflected light is received when pulsed light is reflected by an object located at the end position.

[0037] FIG. 6 is an example of a speed-attention distance table TB3 included in range pattern database 33B. The speed-attention distance table TB3 is a table showing the relationship between the vehicle speed of automobile M and the attention distance. In the speed-attention distance table TB3, speed categories are defined in order of decreasing vehicle speed as "very slow," "low," "medium," "medium-high speed," and "high speed." The speeds corresponding to each category are as follows: "very slow" is 0-20 km / h, "low" is 20-40 km / h, "medium" is 40-60 km / h, "medium-high speed" is 60-80 km / h, and "high" is speeds higher than 80 km / h. The attention distances corresponding to the speed categories are defined in order of decreasing vehicle speed as "close," "near," "medium," "slightly far," and "far."

[0038] In the distance measuring device 10, for example, based on the information stored in the map information database 33A and the range pattern database 33B, a peak of the light receiving signal based on the reflected light RL to be used for detecting the target object is selected from the light receiving signals at a predetermined time after emitting a pulse of laser light LL.

[0039] Specifically, in the distance measuring device 10, a plurality of individual time ranges corresponding to a plurality of individual distance ranges are individually set during a reception period in which reflected light RL of laser light LL, which is one pulsed light, is received, based on, for example, information stored in the map information database 33A or the range pattern database 33B. These individual time ranges are set, for example, based on the attention distance determined based on the road information table TB1 and the speed-attention distance table TB3 and the range pattern table TB2.

[0040] Then, in each of the individual time ranges, a peak of the light receiving signal based on the reflected light RL to be used for detecting the object is selected. For example, as described above, in each of the individual time ranges, the highest peak of the light receiving signal is selected, and the selected peak of the light receiving signal is used for detecting the object and calculating the distance to the object.

[0041] As described above, in the distance measuring device 10, for example, each of the individual distance ranges is set variably depending on the distance of interest. In other words, in the distance measuring device 10, each of the individual time ranges is set variably.

[0042] The control unit 35 is configured with a CPU (Central Processing Unit) 35A, a ROM (Read Only Memory) 35B, a RAM (Random Access Memory) 35C, etc., and functions as a computer. The CPU 35A reads and executes various programs stored in the ROM 35B and the large-capacity storage device 33, thereby realizing various functions.

[0043] The emission control unit 36 ​​is communicatively connected to the laser emission and reception unit 20, and can transmit a control signal to the laser emission and reception unit 20 to control the operation of the laser emission and reception unit 20. For example, in response to a control signal from the emission control unit 36, the light emission unit 21 can scan the laser light LL as pulsed light toward a predetermined area, for example, in front of the automobile M.

[0044] The input unit 37 is communicatively connected to the laser emitting and receiving unit 20, and can receive from the laser emitting and receiving unit 20 a received light signal that includes a peak when the light receiving unit 23 receives the reflected light RL. The control unit 35 can calculate the distance between the object that reflected the laser light LL and the distance measuring device 10 or the automobile M, based on the peak included in the received signal. For example, the control unit 35 can calculate the distance to the object using a so-called TOF (Time Of Flight) method, based on the emission time of the laser light LL and the occurrence time of the peak included in the received light signal.

[0045] The data communication unit 38 is an interface unit that communicably connects the distance measuring device 10 with an external device that is a device outside the distance measuring device 10. For example, the control unit 35 is communicably connected via the data communication unit 38 to a GPS receiver GP that can receive signals (GPS signals) from GPS (Global Positioning System) satellites. This GPS receiver GP may be mounted on the automobile M or may be built into the distance measuring device 10.

[0046] The control unit 35 can acquire GPS signals from the GPS receiver GP via the data communication unit 38 and recognize the current position of the distance measuring device 10 or the automobile M equipped with the distance measuring device 10. For example, the control unit 35 identifies the road and section on which the automobile M is currently traveling from the recognized current position, and compares the identified section with the road information table TB1 to determine the above-mentioned target distance.

[0047] Furthermore, for example, the control unit 35 is communicably connected via the data communication unit 38 to a speed sensor SS that is mounted on the automobile M and is capable of detecting the speed of the automobile M. The control unit 35 can acquire a speed signal from the speed sensor SS via the data communication unit 38 and recognize the speed of the distance measuring device 10 or the automobile M in which the distance measuring device 10 is mounted. For example, the control unit 35 compares the recognized speed with a speed-attention distance table TB3 to determine the above-mentioned attention distance.

[0048] Furthermore, for example, the control unit 35 is communicably connected via the data communication unit 38 to a camera CM that is mounted on the automobile M and is capable of capturing images of the surroundings of the automobile M. The control unit 35 may determine the attention distance based on the video or images captured by the camera CM. Based on the video or images captured by the camera CM, it is possible to obtain information useful for determining the attention distance, such as the number and positions of objects present around the automobile M, the road environment, or weather conditions.

[0049] Furthermore, for example, the control unit 35 may be communicably connected to an external server (not shown) via the data communication unit 38. The control unit 35 may determine the attention distance based on information obtained from the external server. Examples of information obtained from the external server include the weather around the automobile M.

[0050] In addition, the control unit 35 can obtain the driving conditions of the automobile M and the environment and conditions around the automobile M by comprehensively using the GPS signal from the GPS receiver GP, the image from the camera CM mentioned above, the speed signal from the speed sensor SS, or information from an external server (not shown), and determine the attention distance.

[0051] Specifically, in the distance measuring device 10, a plurality of individual time ranges are individually set in a reception period for receiving reflected light RL of laser light LL, which is one pulsed light, based on the traveling conditions of the automobile M and the environment and conditions around the automobile M. Then, in each of the individual time ranges, a peak of the light reception signal based on the reflected light RL to be used for detecting the target object may be selected.

[0052] The control unit 35 may also transmit the results of determining the distance of interest and the results of setting the individual time ranges together with information about the position or area where the determination and setting were made to an external server via the data communication unit 38. By using this information, it is possible to derive, from statistical processing, a preferred setting mode for the individual time ranges when calculating the distance in a specific position or area, and it is also possible to feed back the results of the statistical processing to the distance measuring device 10.

[0053] [Distance measurement mode] Below, as examples of distance measurement modes, we will explain the modes of distance measurement when the target distance is determined to be "close" and when the target distance is determined to be "far." The target distance is determined and the distance range (areas AR1-AR5) is decided using the above-mentioned tables TB1-TB3.

[0054] Figure 7 shows the distance measurement mode when the target distance is determined to be "close," for example, when automobile M is traveling on a road section whose road attribute is a shopping street, or when automobile M is traveling at a speed in a low speed category (for example, 20 km / h or less).

[0055] When the attention distance is "close," the distance measurement area AR1 is 0m-2m, AR2 is 2m-4m, AR3 is 4m-6m, AR4 is 6m-8m, and AR5 is 8m-100m. In other words, when the attention distance is set to "close," the area very close to the automobile M, less than 10m, is divided into five areas, and detailed detection and distance measurement of the object is performed.

[0056] When the attention distance is set to "close," the area that is very close, 10 m or less, from automobile M is area 1 determined by the attention distance, and it can be said that more individual time ranges are allocated to the time range corresponding to area 1 than to other time ranges. By doing so, for example, in an environment with many pedestrians or when automobile M is traveling at a low speed and there are many objects requiring attention near automobile M, it becomes possible to detect and measure the distance to each object without missing any.

[0057] Figure 8 shows the distance measurement mode when the target distance is determined to be "far," for example, when automobile M is traveling on a road section whose road attribute is a motorway only, or when automobile M is traveling at a speed whose speed classification is high (for example, 80 km / h or higher).

[0058] When the attention distance is "far," the distance measurement area AR1 is 20m-60m, AR2 is 60m-65m, AR3 is 65m-70m, AR4 is 70m-90m, and AR5 is 90m-100m. In other words, when the attention distance is set to "far," detection and distance measurement of objects are not performed in areas closer than 20m from the automobile M.

[0059] In this case, for example, the appropriate inter-vehicle distance at a speed faster than 80 km / h is 60 m or more, that is, the distance where many other vehicles are expected to be present, is divided into multiple regions and object detection and distance measurement are performed in detail. When the attention distance is set to "far," the relatively far region of 60 m to 90 m from vehicle M is region 1 determined by the attention distance, and it can be said that more individual time ranges are allocated to the time range corresponding to this one region than to other time ranges.

[0060] By doing this, for example, in an environment where there are only cars traveling at high speeds around, or when car M is traveling at high speed and there are no objects requiring attention near car M but there are many objects requiring attention in the distance, it becomes possible to detect and measure the distance to all objects without missing any.

[0061] According to the configuration described above, it is possible to detect an object and calculate the distance while changing the distance range to be noted depending on, for example, the surrounding environment or driving conditions of the automobile M equipped with the multi-echo distance measuring device 10. Specifically, for example, in the distance range to be noted, it is possible to select or extract signal peaks for each range that is smaller than the other distance ranges and calculate the distance to the object.

[0062] This allows for the proper selection or extraction of truly necessary signal peaks related to an object of interest, enabling more appropriate and efficient detection of the object and calculation of the distance to the detected object. In other words, it is possible to efficiently detect an object of interest and calculate the distance while keeping the data processing and data transfer load low without increasing the number of peaks used for object detection and distance calculation. In other words, the distance measuring device 10 of this embodiment makes it possible to realize a multi-echo distance calculation device that can properly acquire meaningful object detection information while reducing the amount of data processing and data transfer.

[0063] [Distance measurement control routine] The following describes a distance calculation routine executed by the control unit 35 to realize the distance calculation operation of the distance measuring device 10 of the first embodiment.

[0064] 9 is a flow diagram of a distance calculation routine R1, which is an example of a distance calculation routine. For example, the distance calculation routine R1 is started and repeatedly executed when power is supplied to the distance measuring device 10. The distance calculation routine R1 may also be started when the ACC power supply of the automobile in which the distance measuring device 10 is installed is turned on.

[0065] In addition, the distance measuring operation of the distance measuring device 10 starts when power is supplied to the distance measuring device 10, and when the distance measuring operation of the distance measuring device 10 starts, pulsed light is scanned from the light emitting unit 21 of the laser emitting and receiving unit 20 toward the front of the automobile M, and a light receiving signal corresponding to the light incident on the light receiving unit 23 is sent to the control unit 35.

[0066] When the distance calculation routine R1 starts, the control unit 35 waits for reception of a light reception signal from the light receiving unit 23, and in step S11 determines whether or not at least one light reception signal to be used for calculating the distance using one pulse of light has been acquired. Specifically, it determines whether or not at least one series of light reception signals has been acquired from the emission time of one pulse of light to the time when reflected light from the end point of the distance measurement range is expected to return to the light receiving unit 23.

[0067] If it is determined that the series of light receiving signals has not been acquired (step S11: NO), the control unit 35 waits until the series of light receiving signals is acquired, and repeats step S11.

[0068] When the control unit 35 determines that a series of light receiving signals has been acquired (step S11: YES), it acquires a target distance that should be noted in distance measurement (step S12). The target distance is acquired based on, for example, the position of the automobile M, the speed of the automobile M, or the environment around the automobile M, as described above.

[0069] After acquiring the attention distance in step S12, the control unit 35 sets, based on the attention distance, an individual time range for selecting a peak of a received light signal based on the reflected light RL to be used for detecting an object, as described above (step S13). This individual time range may be set based on the acquired attention distance, as described above. Specifically, for example, the individual time range may be set by calculating an individual time range corresponding to the individual distance range determined based on the attention distance.

[0070] For example, each of the individual time ranges is set as the range between the time at which the reflected light RL reaches the light receiving unit 23 when the laser light LL is reflected at the start of each of the individual distance ranges and the time at which the reflected light RL reaches the light receiving unit 23 when the laser light LL is reflected at the end of each of the individual distance ranges.

[0071] After step S13 is completed, the control unit 35 selects a peak of the received light signal for each of the set individual time ranges (step S14). This selection may be performed, for example, by selecting the largest peak of the received light signal for each of the individual time ranges. In steps S12 to S14, the control unit 35 functions as a selection unit.

[0072] After step S14 is completed, the control unit 35 detects the object and calculates the distance using the selected peak of the received light signal (step S15). This detection of the object and calculation of the distance are performed using the so-called TOF (Time Of Flight) method, as described above. Specifically, for example, the distance can be calculated by subtracting the emission time of the laser light LL from the detection time of the peak in the received light signal, multiplying the result by the speed of light, and dividing the result by 2. In step S15, the control unit 35 also functions as a calculation unit.

[0073] After step S15 is completed, the distance calculation routine R1 is completed.

[0074] In the above embodiment, the maximum peak of the received light signal is selected for each individual time range, and the distance is calculated based on the selected peak. However, multiple peaks of the received light signal may be selected for each individual time range as the peak to be used for calculating the distance.

[0075] In the above embodiment, individual time ranges are set by dividing a series of time ranges, but the individual time ranges may be discontinuous or overlap each other.

[0076] In the above embodiment, the attention distance is determined using the road information table TB1 and the speed-attention distance table TB3. However, the attention distance and individual time ranges may be determined based on other information in addition to these. For example, the attention distance may be corrected depending on the weather conditions. For example, in bad weather such as rain or snow, visibility may be reduced and it may be necessary to pay attention to relatively closer positions than usual. Therefore, the attention distance may be shortened or individual time ranges may be adjusted depending on the poor weather.

[0077] Alternatively, the focus distance and the individual time ranges may be determined based solely on weather conditions. For example, when the weather is good, the focus distance may be set to a relatively long distance, and the individual time ranges may be allocated more to the time ranges corresponding to the long distance. Furthermore, the worse the weather, for example, the worse the visibility, the closer the focus distance may be set, and the more the individual time ranges may be allocated to the time ranges corresponding to the short distance.

[0078] Furthermore, the attention distance and the individual time ranges may be determined according to the emission direction of the laser light LL. For example, when the laser light LL is emitted toward the front of the automobile M, the attention distance may be set to a relatively long distance, and many of the individual time ranges may be allocated to time ranges corresponding to that long distance. And, for example, the larger the angle formed between the front direction of the automobile M and the emission direction of the laser light LL, i.e., the more the emission direction of the laser light LL is directed toward the side of the automobile M, the closer the attention distance may be set to a short distance, and many of the individual time ranges may be allocated to time ranges corresponding to short distances.

[0079] Furthermore, the attention distance or the individual time range may be adjusted based on the video from the camera CM or the calculation result of the actual distance by the distance measuring device 10. For example, a position where many objects actually exist or are predicted to exist may be identified based on the video from the camera CM or the calculation result of the actual distance by the distance measuring device 10, and the attention distance or the individual time range may be adjusted based on the identification result. Specifically, a large number of individual time ranges may be arranged for an area around a position where many objects actually exist or are predicted to exist.

[0080] When passing a predetermined position, the distance measuring device 10 may determine whether a landmark as an object detectable from that position has been detected, thereby determining whether distance measurement has been performed properly. The distance measuring device 10 may also transmit the landmark detection result to an external server, and feedback may be provided based on that information to enable better distance measurement.

[0081] Specifically, for example, if a landmark cannot be detected, feedback may be given that the individual time range set at that time is inappropriate and that a different individual time range should be set to calculate the distance.Furthermore, for example, if a landmark is detected, feedback may be given that the individual time range set at that time is appropriate and that the distance should be calculated using the individual time range set.

[0082] The various configurations in the above-described embodiments are merely examples, and can be selected appropriately depending on the application. [Explanation of symbols]

[0083] 10 Ranging device 20 Light emitting / receiving part 21 Light emitting part 23 Light receiving part 30 Controllers 33 Mass storage 35 Control Unit 36. Emission control section 37 Input section 38 Data Communications Department TB1 Road Information Table TB2 Range Pattern Table TB3 Speed-Notice Distance Table

Claims

1. a light emitting unit that emits pulsed light in a variable direction; a light receiving unit that receives light reflected by an object from the pulsed light and generates a light receiving signal; a selector that variably sets each of a plurality of individual time ranges included in a predetermined time range after the pulsed light is emitted, and selects at least one signal intensity peak from among the signal intensity peaks of the received light signal in each of the plurality of individual time ranges; a calculation unit that calculates a distance to the object based on the peak of signal strength selected by the selection unit, a selection unit that sets each of the plurality of individual time ranges to a time range corresponding to the surrounding environment of the distance calculation device, the surrounding environment being determined based on the current position of the distance calculation device, an image captured by an imaging unit that captures the scenery around the distance calculation device, or the weather around the distance calculation device received from an external server.

2. The distance calculation device according to claim 1, characterized in that the light receiving unit receives a plurality of reflected lights of the pulsed light reflected by a plurality of the objects for each of the pulsed light, and generates a series of light receiving signals in which the light receiving signals corresponding to each of the pulsed light are connected.

3. 3. The distance calculation device according to claim 1, wherein the surrounding environment includes attributes of a road on which the distance calculation device is located, weather around the distance calculation device, or the number or locations of objects around the distance calculation device.

4. 2. The distance calculation device according to claim 1, wherein the selection unit variably sets each of the plurality of individual time ranges according to the emission direction of each of the pulsed beams with respect to the plurality of objects.

5. The distance calculation device according to claim 1 , wherein the selection unit variably sets each of the individual time ranges depending on the state of distance measurement of the plurality of objects.

6. the distance calculation device is mounted on a moving body, 5. The distance calculation device according to claim 1, wherein the selection unit variably sets each of the individual time ranges based on a traveling state of the mobile object.

7. 7. The distance calculation device according to claim 6, wherein the selection unit variably sets each of the individual time ranges in accordance with the moving speed of the moving object.

8. The distance calculation device according to claim 6, characterized in that the selection unit determines a cautionary distance, which is a distance at which there are many objects to be measured, based on the surrounding conditions of the distance calculation device, and sets the individual time range based on the cautionary distance.

9. The distance calculation device according to claim 8 , wherein the selection unit sets the individual time ranges so that more of the individual time ranges are located in one time range determined based on the distance to be careful than in other time range periods.

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