Distance measuring device

Abstract

The present invention provides a distance measuring device. A background light calculation unit (S90) calculates background light quantity parameters associated with the quantity of background light from the azimuth area for multiple azimuth areas. A coefficient calculation unit (S260) calculates the cumulative coefficient of the object azimuth area and multiple surrounding azimuth areas in a manner that has a negative correlation with the difference between the background light quantity parameters of the surrounding azimuth areas and the background light quantity parameters of the object azimuth area. A multiple waveform generation unit (S270) generates coefficient-multiplied waveform data for the distance measurement waveform data of the object azimuth area and multiple surrounding azimuth areas by multiplying the distance measurement waveform data by the corresponding cumulative coefficient. A cumulative waveform generation unit (S280) generates cumulative waveform data by accumulating the coefficient-multiplied waveform data of the object azimuth area and multiple surrounding azimuth areas.

Description

Technical Field

[0001] The present invention relates to a distance measuring device for irradiating light and measuring the distance to an object reflecting the light. Background Art

[0002] Patent document 1 describes a distance measuring device comprising: a scanning unit that scans a laser projected by a light-projecting unit; a light-receiving unit that receives reflected light corresponding to the laser projected at a predetermined interval; an accumulation unit that accumulates a time series of light intensity signals output by the light-receiving unit; and a distance calculation unit that calculates the distance to an object based on the accumulation performed by the accumulation unit.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-109560

[0004] However, as a result of detailed studies, the inventors have discovered the following problem: in the technology described in Patent Document 1, the detection sensitivity of reflected light is low due to the influence of noise detected by the light receiving unit. Summary of the invention

[0005] The present invention improves the detection sensitivity of reflected light.

[0006] One embodiment of the present invention is a distance measuring device including an irradiation unit, a light detection unit, a background light calculation unit, an object direction selection unit, a coefficient calculation unit, a distance measurement waveform generation unit, a multiple waveform generation unit, an accumulation waveform generation unit, and a measurement unit.

[0007] The irradiation unit is configured to irradiate light, and the light detection unit is configured to detect reflected light.

[0008] The background light calculation unit is configured to calculate a background light amount parameter associated with the amount of background light from the azimuth area based on the detection result of the light detection unit for each of the plurality of azimuth areas formed by dividing the light irradiation area of ​​the irradiated light.

[0009] The target direction selection unit is configured to sequentially select one direction area from among the plurality of direction areas as the target direction area.

[0010] The coefficient calculation unit is configured to calculate the cumulative coefficient of the target azimuth area and each of the plurality of surrounding azimuth areas in a manner that is negatively correlated with the difference between the background light amount parameter of the surrounding azimuth area and the background light amount parameter of the target azimuth area. The surrounding azimuth area is an azimuth area arranged around the target azimuth area selected by the target azimuth selection unit.

[0011] The distance measurement waveform generation unit is configured to generate distance measurement waveform data representing a time change of a light detection parameter from the time of irradiation of light to the time when a preset distance measurement period has elapsed for each of the plurality of azimuth regions. The light detection parameter is a parameter representing a detection result of the light detection unit.

[0012] The multiplied waveform generating unit is configured to generate coefficient-multiplied waveform data by multiplying the distance measurement waveform data by a corresponding accumulation coefficient for each of the distance measurement waveform data of the target azimuth region and the plurality of peripheral azimuth regions.

[0013] The cumulative waveform generating unit is configured to generate cumulative waveform data by accumulating the coefficient-multiplied waveform data of the target azimuth region and the plurality of peripheral azimuth regions.

[0014] The measuring unit is configured to measure a distance to an object reflecting light using the integrated waveform data generated by the integrated waveform generating unit.

[0015] The distance measuring device of the present invention constructed in this way accumulates coefficient-multiplied waveform data of the target azimuth region and multiple peripheral azimuth regions in order to measure the distance to an object existing in the azimuth corresponding to the target azimuth region, thereby reducing randomly generated noise in the accumulated waveform data.

[0016] Furthermore, the distance measuring device of the present invention calculates the cumulative coefficient in a manner that has a negative correlation with the difference between the background light amount parameter of the peripheral azimuth region and the background light amount parameter of the target azimuth region, and generates the coefficient-multiplied waveform data by multiplying the distance measuring waveform data by the corresponding cumulative coefficient. Thus, in the case where the background light amount of the peripheral azimuth region is greater than the background light amount of the target azimuth region, the distance measuring device of the present invention can reduce the contribution of the distance measuring waveform data of the peripheral azimuth region in the accumulated waveform data. Therefore, in the case where the background light amount of the peripheral azimuth region is greater than the background light amount of the target azimuth region, the distance measuring device of the present invention can suppress the situation where the noise of the accumulated waveform data is greater than the noise of the distance measuring waveform data of the target azimuth region, and can further reduce the noise in the accumulated waveform data.

[0017] In summary, the distance measuring device of the present invention can improve the detection sensitivity of the reflected light detected by the light detection unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a block diagram showing the brief structure of an optical radar device.

[0019] Figure 2 It is a three-dimensional diagram of an optical radar device.

[0020] Figure 3 is a three-dimensional diagram of the light detection module.

[0021] Figure 4 FIG. 1 is a front view of the light detection module with a portion of the frame removed.

[0022] Figure 5 It is a top view of the optical radar device without the shell.

[0023] Figure 6 It is a diagram showing the structure of a reflector module.

[0024] Figure 7 It is a diagram showing the structure of a light source.

[0025] Figure 8 It is a diagram showing the structure of a light receiving element.

[0026] Fig. 9 It is a diagram showing the path of light when projecting light.

[0027] Fig.10 It is a diagram showing the path of light when receiving light.

[0028] Fig.11 This is a diagram for explaining the position adjustment of the light source and the light receiving element.

[0029] Fig.12 It is a diagram showing the irradiation range of the light beam emitted from the deflecting mirror.

[0030] Fig.13 This is a diagram showing the correspondence between the light emitting area of ​​the light source and the light receiving area of ​​the light receiving element.

[0031] Fig.14 : is a flowchart showing the data acquisition process.

[0032] Fig.15 This is a diagram showing a plurality of azimuth areas and background light waveform data set in a two-dimensional matrix.

[0033] Fig.16 This is a diagram showing a plurality of azimuth areas and distance measurement waveform data set in a two-dimensional matrix.

[0034] Fig.17 : is a flowchart showing the cumulative distance measurement process according to the first embodiment.

[0035] Fig.18 It is a diagram showing the position of an object and the positions of its neighbors.

[0036] Fig.19 This is a diagram for explaining the calculation of the noise value.

[0037] Fig. 20 It is a diagram showing a specific example of the cumulative coefficient and a specific example of the formula (1).

[0038] Fig.21 This is a diagram for explaining calculation of accumulated waveform data.

[0039] Fig. 22 : is a flowchart showing the cumulative distance measurement process according to the second embodiment.

[0040] Fig.23 : is a flowchart showing the cumulative distance measurement process according to the third embodiment.

[0041] Fig.24 : is a flowchart showing the cumulative distance measurement process according to the fourth embodiment.

[0042] Fig.25 : is a flowchart showing the cumulative distance measurement process according to the fifth embodiment.

[0043] Fig.26 It is a diagram showing a normal distribution of a low light intensity standard deviation and a normal distribution of a high light intensity standard deviation. DETAILED DESCRIPTION

[0044] (First Embodiment)

[0045] Hereinafter, a first embodiment of the present invention will be described based on the drawings.

[0046] The optical radar device 1 of this embodiment is mounted on a vehicle and used to detect various objects existing around the vehicle. An optical radar is also referred to as LIDAR. LIDAR is an abbreviation of Light Detection and Ranging.

[0047] like Figure 1 As shown, the optical radar device 1 includes a light detection module 2 and a control unit 3 described later. The control unit 3 is an electronic control device centered on a microcomputer including a CPU 61, a ROM 62, and a RAM 63. The various functions of the microcomputer are realized by the CPU 61 executing a program stored in a non-transitional physical recording medium. In this example, the ROM 62 is equivalent to a non-transitional physical recording medium storing a program. In addition, by executing the program, a method corresponding to the program is executed. In addition, a part or all of the functions performed by the CPU 61 may be constituted in hardware by one or more ICs, etc. In addition, the number of microcomputers constituting the control unit 3 may be one or more.

[0048] The vehicle speed sensor 71, the front camera 72, and the navigation device 73 are connected to the control unit 3. The vehicle speed sensor 71 detects the travel speed (hereinafter, the vehicle speed) of the vehicle (hereinafter, the vehicle) equipped with the optical radar device 1, and outputs a vehicle speed detection signal indicating the detection result to the control unit 3. The front camera 72 is installed on the front side of the vehicle and repeatedly photographs the ground in front of the vehicle.

[0049] The navigation device 73 acquires the road map data from a map recording medium recording the road map data and various information, detects the current position of the vehicle based on the GPS signal received via the GPS antenna, and performs route guidance from the current position to the destination, etc. In addition, the above-mentioned road map data includes various data such as road position, road type, road shape, road width, road name, number of lanes, and road slope.

[0050] like Figure 2 As shown, the optical radar device 1 includes a housing 100 and an optical window 200 .

[0051] The housing 100 is a resin box body formed into a rectangular parallelepiped having an opening on one of the six sides, and accommodates a light detection module 2 to be described later.

[0052] The optical window 200 is a resin cover fixed to the housing 100 so as to cover the opening of the housing 100. The laser beam irradiated from the light detection module 2 provided inside the housing 100 passes through the inside of the optical window 200.

[0053] Hereinafter, the direction along the long side of the opening formed in a substantially rectangular shape is defined as the X-axis direction, the direction along the short side of the opening is defined as the Y-axis direction, and the direction orthogonal to the X-axis direction and the Y-axis direction is defined as the Z-axis direction. In addition, the left and right in the X-axis direction and the up and down in the Y-axis direction are defined as viewed from the opening side of the housing 100. In addition, the front and back in the Z-axis direction define the opening side of the housing 100 as the front, and the depth side as the back.

[0054] like Figure 3 , Figure 4 as well as Figure 5 As shown, the light detection module 2 includes a light projecting unit 10, a scanning unit 20, a light receiving unit 30, and a frame 40. The light detection module 2 is assembled to the housing 100 via the frame 40.

[0055] The scanning unit 20 includes a mirror module 21 , a partition plate 22 , and a motor 23 .

[0056] like Figure 6 As shown, the mirror module 21 includes a pair of deflecting mirrors 211 and 212 and a mirror frame 213 .

[0057] A pair of deflection mirrors 211 and 212 are flat plate-shaped components having a reflecting surface for reflecting light. The reflector frame 213 includes a circular plate portion 213a and a fixed portion 213b. The circular plate portion 213a is a circular plate-shaped portion, the center of which is fixed to the rotating shaft of the motor 23. The fixed portion 213b is a plate-shaped portion to which the deflection mirrors 211 and 212 are fixed on both sides. The fixed portion 213b is formed to protrude vertically from the circular surface of the circular plate portion 213a relative to the circular surface of the circular plate portion 213a.

[0058] The deflecting mirrors 211, 212 and the fixed portion 213b each have a shape in which two rectangles of different widths in the long side direction are integrated. Specifically, the two rectangles have a shape in which the central axes along the short side direction are aligned and arranged along the central axis and integrated. Hereinafter, in the reflector module 21, the portion of the rectangle with a narrower long side direction among the portions in which the deflecting mirrors 211, 212 and the fixed portion 213b are integrated is referred to as a narrow width portion, and the portion of the rectangle with a wider long side direction is referred to as a wide width portion.

[0059] The pair of deflecting mirrors 211 and 212 integrated via the reflector frame 213 are arranged so that the position of the central axis coincides with the center of the circle of the circular plate portion 213a when the wide portion is lower than the narrow portion, and protrudes perpendicularly from the circular surface of the circular plate portion 213a relative to the circular surface of the circular plate portion 213a. Thus, the deflecting mirrors 211 and 212 can rotate around the rotation axis of the motor 23 according to the drive of the motor 23. In addition, the reflecting surfaces of the deflecting mirrors 211 and 212 are always parallel to the rotation axis of the motor 23 regardless of the rotation position of the motor 23.

[0060] The partition plate 22 is a disc-shaped member having the same diameter as the width in the long-side direction of the wide width portion of the reflector module 21. The partition plate 22 is divided into two semicircular portions. Moreover, these two semicircular portions sandwich the narrow width portion of the reflector module 21 from both sides and are fixed in a state of contact with the stepped portion of the wide width portion and the narrow width portion of the reflector module 21.

[0061] Hereinafter, in the deflecting mirrors 211 and 212, the portion above the partition plate 22 (i.e., the portion on the narrow width side) is referred to as the light projection deflection portion 20a, and the portion below the partition plate 22 (i.e., the portion on the wide width side) is referred to as the light receiving deflection portion 20b.

[0062] like Figure 3 to Figure 5 As shown, the light projecting unit 10 includes a pair of light sources 11 and 12 , a pair of light projecting lenses 13 and 14 , and a light projecting reflecting mirror 15 .

[0063] Since the light sources 11 and 12 have the same structure, only the structure of the light source 11 will be described here. Figure 7As shown, the light source 11 is a so-called multi-stripe semiconductor laser having a plurality of light-emitting regions A1 and A2. The light-emitting regions A1 and A2 are formed into a rectangular shape with their arrangement direction as the long side direction. Moreover, the area width L along the arrangement direction of the light-emitting regions A1 and A2 is set to be greater than the area interval S between the light-emitting regions A1 and A2. Light beams parallel to each other's optical axes are irradiated from each light-emitting region A1 and A2.

[0064] Hereinafter, in the light projection and deflection unit 20a, a point on which the light beams from the light sources 11 and 12 are incident is referred to as a reflection point. In addition, a plane that is orthogonal to the rotation axis and includes the reflection point is referred to as a reference plane.

[0065] like Figure 3 to Figure 5 As shown, the light source 11 is arranged at a position away from the reflection point toward the left side along the X-axis, so that the light-emitting surface is facing the projection deflection unit 20a. The light source 12 is arranged at a position away from the back side along the Z-axis near the turning point of the path from the reflection point to the center of the light source 11, so that the light-emitting surface is facing the front side of the Z-axis. Moreover, regarding the position of the light sources 11 and 12 in the Y-axis direction, the light source 11 is arranged at a position lower than the reference plane, and the light source 12 is arranged at a position higher than the reference plane. In addition, the light sources 11 and 12 are arranged so that the arrangement direction of the light-emitting areas A1 and A2 is consistent with the Y-axis direction.

[0066] The light projection lens 13 is disposed opposite to the light emitting surface of the light source 11. Similarly, the light projection lens 14 is disposed opposite to the light emitting surface of the light source 12. The light sources 11 and 12 are disposed near the focal points of the light projection lenses 13 and 14, respectively.

[0067] The light reflection mirror 15 is disposed at the reflection point, reflects the light emitted from the light source 12 and guides it to the reflection point. Fig. 9 As shown, the light-reflecting mirror 15 is arranged above the path so as not to block the path of the light irradiated from the light source 11 and directed toward the reflection point. In addition, the path of the light from the light source 11 to the reflection point and the path of the light from the light source 12 to the reflection point via the light-reflecting mirror 15 are set to be the same length as each other. In addition, the light source 11 is set so that the optical axis is inclined upward by 1 to 2° relative to the reference plane, and the light source 12 is set so that the optical axis is inclined downward by 1 to 2° relative to the reference plane. In other words, the optical axes of the light sources 11 and 12 are oriented in directions symmetrical with respect to the reference plane. This angle is not limited to 1 to 2° and can be appropriately set according to the desired light beam emission angle in the sub-scanning direction.

[0068] like Figure 3 to Figure 5 As shown, the light receiving unit 30 includes a light receiving element 31 , a light receiving lens 32 , and a light receiving reflecting mirror 33 .

[0069] like Figure 8As shown, the light receiving element 31 includes an avalanche photodiode array 311 (hereinafter, APD array 311) and a lens array 312. APD is the abbreviation of Avalanche Photo Diode. The APD array 311 arranges 12 avalanche photodiodes (hereinafter, APD) in a row. The lens array 312 is 12 lenses arranged opposite to the 12 APDs constituting the APD array 311, and converges the light incident on the light receiving element 31 and guides it to each APD.

[0070] like Figure 4 as well as Fig.10 As shown, the light receiving element 31 is arranged below the light receiving mirror 33 in such a manner that the light receiving surface faces the upper side along the Y axis and the arrangement direction of the APDs in the APD array 311 coincides with the X axis direction. Figure 4 In the figure, a part of the frame 40 is omitted to make it easier to see the configuration of each part.

[0071] The light receiving mirror 33 is disposed on the left side of the light receiving deflection unit 20b along the X axis. The light receiving mirror 33 bends the light path by approximately 90 degrees downward along the Y axis so that light incident from the light receiving deflection unit 20b via the light receiving lens 32 reaches the light receiving element 31.

[0072] The light receiving lens 32 is disposed between the light receiving deflection unit 20b and the light receiving folding mirror 33. The light receiving lens 32 focuses the width of the light beam incident on the light receiving element 31 along the Z-axis direction to about the element width of the APD.

[0073] The frame 40 is a member for integrally assembling the components of the light projector 10, the scanner 20, and the light receiver 30. That is, the components of the light projector 10, the scanner 20, and the light receiver 30 are assembled in the housing 100 with their positional relationships determined.

[0074] like Figure 3 to Figure 5 As shown, the frame 40 includes a frame lower portion 41 , a frame side portion 42 , a frame rear portion 43 , and a partition portion 44 .

[0075] A light receiving substrate 51 on which the light receiving element 31 is assembled and a motor substrate 52 on which the scanning unit 20 is assembled are mounted on the lower side of the frame lower portion 41. Therefore, holes are provided in the frame lower portion 41 at the portion of the path of light from the light receiving reflecting mirror 33 to the light receiving element 31 and at the portion where the motor 23 of the scanning unit 20 is arranged.

[0076] The frame side portion 42 has a surface facing the scanning unit 20, and a cylindrical holder 421 is provided on the surface. The projection lens 13 is assembled to the surface side end (i.e., the right side end in the X-axis direction) of the holder 421 so as to close its opening. In addition, the light emitting substrate 53 assembled with the light source 11 is mounted on the back side of the frame side portion 42. When the light emitting substrate 53 is mounted on the frame side portion 42, the light source 11 is arranged on the back side end (i.e., the left side end in the X-axis direction) of the holder 421.

[0077] The frame back portion 43 is provided with a holder 431 similarly to the frame side portion 42. The projection lens 14 is assembled to the surface side end (i.e., the front side end in the Z-axis direction) of the holder 431. In addition, the light emitting substrate 54 assembled with the light source 12 is mounted on the back side of the frame back portion 43. When the light emitting substrate 54 is mounted on the frame back portion 43, the light source 12 is arranged on the back side end (i.e., the rear side end in the Z-axis direction) of the holder 431.

[0078] The partition 44 is provided at a position to partition a space where components constituting the light projecting unit 10 are arranged and a space where components constituting the light receiving unit 30 are arranged. The light projecting and reflecting mirror 15 , the light receiving and reflecting mirror 33 , and the light receiving lens 32 are assembled in the partition 44 .

[0079] In addition, the light receiving substrate 51 and the light emitting substrates 53 and 54 are fixed to the frame 40 by screws. The optical radar device 1 is configured to independently finely adjust the installation positions and angles of the light receiving element 31 and the light sources 11 and 12 in three dimensions by adjusting the installation positions and angles of the light receiving substrate 51 and the light emitting substrates 53 and 54. In the present embodiment, the holders 421 and 431 are respectively provided integrally with the frame side surface portion 42 and the frame back surface portion 43, but may also be provided integrally with the light emitting substrate 53 and the light emitting substrate 54.

[0080] The control unit 3 is assembled in the housing 100, for example. The control unit 3 controls the light emission timing of the light sources 11 and 12 in synchronization with the rotation of the mirror module 21 of the scanning unit 20. Specifically, the control unit 3 controls so that the light beam from the light source 11 is incident on the deflection mirror 211 and the light beam from the light source 12 is incident on the deflection mirror 212.

[0081] like Fig. 9 As shown, the light irradiated from the light source 11 is incident on the reflection point P of the projection deflection unit 20a via the projection lens 13. In addition, the light irradiated from the light source 12 is incident on the reflection point P of the projection deflection unit 20a after passing through the projection lens 14, and the traveling direction is bent by approximately 90 degrees at the projection return mirror 15. However, different surfaces of the projection deflection unit 20a are used in the light source 11 and the light source 12. The light incident on the reflection point P is emitted in a direction corresponding to the rotation position of the reflector module 21.

[0082] like Fig.10 As shown, the reflected light from the object to be detected located in a predetermined direction corresponding to the rotation position of the reflector module 21 (i.e., the emission direction of the light from the light-projecting deflection unit 20a) is reflected by the light-receiving deflection unit 20b, and is detected by the light-receiving element 31 via the light-receiving lens 32 and the light-receiving reflective mirror 33. In addition, the object to be detected is various object marks that become the detection object of the optical radar device 1.

[0083] That is, in the optical radar device 1, horizontal scanning along the X-axis direction (hereinafter, main scanning) is mechanically realized by the rotation of the reflector module 21. In addition, vertical scanning along the Y-axis direction (hereinafter, sub-scanning) is electronically realized by the light sources 11 and 12 that output four light beams arranged in the vertical direction and the APD array 311 that receives the above four light beams.

[0084] like Figures 9 to 11 As shown, the light sources 11 and 12 are arranged so that the optical path lengths to the reflection point P of the projection and deflection unit 20 a are equal to each other and the optical axes intersect each other at the reflection point P. In addition, the light receiving element 31 is arranged near the focus of the light receiving lens 32 .

[0085] Here, the light beams from the light emitting areas A1 and A2 of the light source 11 are set as B11 and B12, and the light beams from the light emitting areas A1 and A2 of the light source 12 are set as B21 and B22. Fig.12 As shown, among the light beams emitted from the reflection point P of the projection deflection unit 20a, the light beam B11, the light beam B21, the light beam B12, and the light beam B22 are arranged in order from the upper side to the lower side along the Y axis. In addition, the positions of the light sources 11 and 12 are finely adjusted so that there is no gap between the light beams B11, B21, B12, and B22. Fig.13 As shown, on the APD array 311 of the light receiving element 31, fine adjustment is performed in such a way that the reflected light from the object to be detected irradiated with each light beam B11, B21, B12, and B22 is irradiated to the center of each APD in the Z-axis direction and to each of the three different elements.

[0086] In addition, since the reflection surface of the projection and deflection unit 20a is parallel to the rotation axis of the reflector module 21, the inclination angle of the reflection surface in the vertical plane including the incident path of the light toward the projection and deflection unit 20a does not change due to the rotation position of the reflector module 21. The vertical plane here refers to the plane along the Y axis. In other words, Fig.12As shown in the diagram of , no matter what the emission angle (i.e., horizontal angle) of the light emitted from the projection deflection unit 20a toward the X-axis direction as the main scanning direction, the emission angle (i.e., vertical angle) toward the Y-axis direction as the sub-scanning direction is constant. Therefore, within the scanning range set two-dimensionally, the light beam is irradiated without gaps. Hereinafter, the emission angle toward the X-axis direction is referred to as the main scanning angle, and the emission angle toward the Y-axis direction is referred to as the sub-scanning angle.

[0087] Next, the procedure of the data acquisition process executed by the CPU 61 of the control unit 3 will be described. The data acquisition process is a process that is repeatedly executed during the operation of the control unit 3.

[0088] If the data acquisition process is executed, Fig.14 As shown, first, in S10, the CPU 61 determines whether it is the time to obtain the background light after each preset distance measurement cycle. Here, if it is not the time to obtain the background light, the CPU 61 waits by repeatedly performing the processing of S10 until it is the time to obtain the background light. And, if it is the time to obtain the background light, then in S20, the CPU 61 detects the rotation position (i.e., the main scanning angle) of the reflector module 21 by acquiring the scanning angle detection signal from the reflector module 21.

[0089] Then, in S30, the CPU 61 acquires the light detection signal of the light receiving element 31. Furthermore, in S40, the CPU 61 stores the background light detection data indicating the signal intensity of the light detection signal acquired in S30 in the RAM 63.

[0090] like Fig.15 As shown, CPU 61 establishes a correspondence between the light irradiation area Ri of the irradiated laser and any area in a plurality of azimuth areas divided into a two-dimensional matrix according to the main scanning angle and the sub-scanning angle to store background light detection data. The light irradiation area Ri of this embodiment is an area including a main scanning angle of -60° to +60° and a sub-scanning angle of -4° to +4°.

[0091] The plurality of azimuth regions are regions that are equally spaced along the main scanning direction by Nm main scanning direction ranges Rm and equally spaced along the sub-scanning direction by 12 sub-scanning direction ranges Rs. The Nm main scanning direction ranges Rm are recorded as main scanning direction ranges Rm_1, Rm_2, ..., Rm_Nm-1, Rm_Nm in the order of the main scanning angle from small to large. In addition, the 12 sub-scanning direction ranges Rs are recorded as sub-scanning direction ranges Rs_1, Rs_2, Rs_3, Rs_4 ..., Rm_11, Rm_12 in the order of the sub-scanning angle from large to small. In addition, the azimuth region determined by the main scanning direction range Rm_i and the sub-scanning direction range Rs_j is recorded as azimuth region OR(i, j). i is an integer from 1 to Nm. j is an integer from 1 to 12.

[0092] In S40 , specifically, first, the CPU 61 sets one main scanning direction range Rm among the Nm main scanning direction ranges Rm based on the scanning angle detected in S20 .

[0093] Moreover, CPU61 stores each of the signal intensities of the light detection signals from the 12 APDs in a state in which a correspondence is established with the moment when the light detection signal is acquired, the main scanning direction range Rm set above, and the sub-scanning direction range Rs pre-set for the APD (that is, a state in which a correspondence is established between the moment and the azimuth area) as background light detection data in RAM63. In addition, the signal intensities obtained from the three APDs corresponding to the light beam B11 are respectively corresponding to the sub-scanning direction ranges Rs_1, Rs_2, and Rs-3. Similarly, the signal intensities obtained from the three APDs corresponding to the light beam B21 are respectively corresponding to the sub-scanning direction ranges Rs_4, Rs_5, and Rs_6. The signal intensities obtained from the three APDs corresponding to the light beam B12 are respectively corresponding to the sub-scanning direction ranges Rs_7, Rs-8, and Rs_9. The signal intensities obtained from the three APDs corresponding to the light beam B22 are respectively corresponding to the sub-scanning direction ranges Rs_10, Rs_11, and Rs_12.

[0094] Next, if Fig.14 As shown, in S50, CPU61 determines whether the irradiation timing of the background light acquisition period set in advance has been reached since the background light acquisition timing. Here, if the irradiation timing has not been reached, CPU61 moves to S30. On the other hand, if the irradiation timing has been reached, in S60, CPU61 causes light sources 11 and 12 to irradiate light beams.

[0095] Then, in S70, the CPU 61 generates 12 background light waveform data corresponding to each of the sub-scanning direction ranges Rs_1, Rs_2, Rs_3, ..., Rs_11, and Rs_12 based on the background light detection data acquired through the processing of S30 and S40, and stores the data in the RAM 63. The background light waveform data represents the time change of the signal intensity from the background light acquisition timing to the irradiation timing.

[0096] Furthermore, any one of the main scanning direction range Rm and the sub-scanning direction ranges Rs_1, Rs_2, Rs_3, ..., Rs_11, and Rs_12 set above is set in the background light waveform data. Fig.15 As shown by arrow L1, the background light waveform data D1 is stored in the RAM 63 in a state of being associated with the azimuth area.

[0097] Next, if Fig.14 As shown, in S80, the CPU 61 performs filtering processing on the background light waveform data generated in S70. In this embodiment, the CPU 61 performs filtering processing using a bidirectional filter. The bidirectional filter is a filter that maintains edges and performs smoothing.

[0098] In addition, in S90, the CPU 61 calculates the noise value of the background light waveform data subjected to the filtering process in S80, and stores it in the RAM 63. Fig.15 As shown in FIG. 1 , the noise value is the standard deviation of the signal intensity in the background light waveform data. As described above, the background light waveform data is set with any of the main scanning direction range Rm and the sub-scanning direction ranges Rs_1, Rs_2, Rs_3, ..., Rs_11, and Rs_12. Therefore, Fig.15 As shown by arrow L2, the noise value is stored in RAM 63 in a state of being associated with the azimuth area.

[0099] Next, if Fig.14 As shown, in S100, the CPU 61 calculates the full-range standard deviation Var. The full-range standard deviation Var is the standard deviation of the noise values ​​in all azimuth regions OR (i, j). However, when the noise value in at least one azimuth (i, j) in all azimuth regions OR (i, j) is not stored in the RAM 63, the CPU 61 does not calculate the full-range standard deviation Var.

[0100] Next, in S110, the CPU 61 acquires the light detection signal of the light receiving element 31. Furthermore, in S120, the CPU 61 stores the distance measurement data indicating the signal strength of the light detection signal acquired in S110 in the RAM 63.

[0101] Specifically, in S120 , first, the CPU 61 sets one main scanning direction range Rm among the Nm main scanning direction ranges Rm based on the scanning angle detected in S20 .

[0102] Then, similar to S40, CPU61 stores the signal strengths of the light detection signals from the 12 APDs in RAM63 as ranging data in a state in which a correspondence is established between the moment when the light detection signal is acquired, the main scanning direction range Rm set above, and the sub-scanning direction range Rs pre-set for the APD (i.e., a state in which a correspondence is established between the moment and the azimuth area).

[0103] Next, in S130, CPU61 determines whether the ranging end timing has been reached after a preset ranging period has passed since the irradiation timing. Here, if the ranging end timing has not been reached, CPU61 moves to S110. On the other hand, in the case of reaching the end timing, in S140, CPU61 generates 12 ranging waveform data corresponding to each range in the sub-scanning direction ranges Rs_1, Rs_2, Rs_3, ..., Rs_11, and Rs_12 based on the ranging data acquired in the processing of S110 and S120, and stores them in RAM63. The ranging waveform data represents the time change of the signal intensity from the irradiation timing to the ranging end timing.

[0104] Furthermore, any one of the main scanning direction range Rm and the sub-scanning direction ranges Rs_1, Rs_2, Rs_3, ..., Rs_11, and Rs_12 set above is set in the distance measurement waveform data. Fig.16 As shown by arrow L3, the distance measurement waveform data D2 is stored in RAM 63 in a state of being associated with the azimuth area.

[0105] Then, when the process of S140 is completed, the CPU 61 ends the data acquisition process.

[0106] Next, the procedure of the cumulative distance measurement process executed by the CPU 61 of the control unit 3 will be described. The cumulative distance measurement process is a process that is repeatedly executed during the operation of the control unit 3.

[0107] If cumulative ranging processing is performed, Fig.17 As shown, first, in S210, the CPU 61 determines whether the latest omnidirectional standard deviation Var calculated in S100 is greater than a preset distance determination value J1. Here, when the omnidirectional standard deviation Var is less than the distance determination value J1, the CPU 61 ends the cumulative distance measurement process.

[0108] On the other hand, when the omnidirectional standard deviation Var is greater than the distance determination value J1, in S220, the CPU 61 sets the column indication value n set in the RAM 63 to 1, and sets the end column indication value Nend set in the RAM 63 to Nm. Hereinafter, the azimuth area OR (n, 1), the azimuth area OR (n, 2), the azimuth area OR (n, 3), and the azimuth area OR (n, 4) are referred to as the nth column azimuth area.

[0109] Then, in S230, the CPU 61 determines whether the background light waveform data corresponding to the azimuth area of ​​the (n+1)th column is updated according to the previous cumulative ranging process. Here, when the background light waveform data of the azimuth area of ​​the (n+1)th column is not updated, the CPU 61 waits by repeating the process of S230 until the background light waveform data is updated. And, if the background light waveform data is updated, then in S240, the CPU 61 sets the row indication value m set in the RAM 63 to 1. Hereinafter, the azimuth area OR (n, m) is referred to as the azimuth area of ​​the nth column and the mth row.

[0110] Next, in S250, CPU61 sets the azimuth area of ​​the nth column and the mth row as the object azimuth area. Further, in S260, CPU61 calculates the cumulative coefficient for the object azimuth area and the adjacent azimuth areas adjacent to the object azimuth area using the noise value calculated in S90. The object azimuth area is the azimuth area OR(n, m). The adjacent azimuth areas are the azimuth area OR(n-1, m-1), the azimuth area OR(n-1, m), the azimuth area OR(n-1, m+1), the azimuth area OR(n, m-1), the azimuth area OR(n, m+1), the azimuth area OR(n+1, m-1), the azimuth area OR(n+1, m), and the azimuth area OR(n+1, m+1). For example, Fig.18 As shown, when the direction at the second row of the nth column is set as the target direction area, the target direction area is the direction area OR0, and the adjacent direction areas are the direction areas OR1, OR2, OR3, OR4, OR5, OR6, OR7, and OR8.

[0111] In the following, the azimuth area OR (n-1, m-1) is referred to as the first adjacent azimuth. The azimuth area OR (n-1, m) is referred to as the second adjacent azimuth area. The azimuth area OR (n-1, m+1) is referred to as the third adjacent azimuth area. The azimuth area OR (n, m-1) is referred to as the fourth adjacent azimuth area. The azimuth area OR (n, m+1) is referred to as the fifth adjacent azimuth area. The azimuth area OR (n+1, m-1) is referred to as the sixth adjacent azimuth area. The azimuth area OR (n+1, m) is referred to as the seventh adjacent azimuth area. The azimuth area OR (n+1, m+1) is referred to as the eighth adjacent azimuth area.

[0112] Specifically, in S260, the CPU 61 sets the noise value of the target orientation area to Vn(0), such as Fig.19 As shown, the noise value of the kth adjacent azimuth area is set to Vn(k), and the cumulative coefficient W(0) of the target azimuth area and the cumulative coefficient W(k) of the kth adjacent azimuth area are calculated by the following formula (1). σ in the following formula (1) is the standard deviation of the normal distribution. The value of σ is preset.

[0113] W(k)=exp{(Vn(0)-Vn(k)) 2 / 2σ 2}…(1)

[0114] Fig. 20 The graph G1 is a specific example of the formula (1). (Vn(0)-Vn(k)) in the formula (1) corresponds to the noise value difference on the horizontal axis of the graph G1.

[0115] Fig. 20 The matrix M1 is a specific example of the cumulative coefficients of the object azimuth region and the first to eighth adjacent azimuth regions. The matrix M1 indicates that the cumulative coefficient of the object azimuth region is 1, the cumulative coefficient of the first to third adjacent azimuth regions is 0.1, the cumulative coefficient of the fourth, fifth, and seventh adjacent azimuth regions is 0.6, and the cumulative coefficient of the sixth and eighth adjacent azimuth regions is 0.9.

[0116] Further, if Fig.17 As shown, in S270, the CPU 61 multiplies the signal strength of the ranging waveform data of each data in the ranging waveform data of the target azimuth area and the first to eighth adjacent azimuth areas by the cumulative coefficient calculated in S260. That is, the CPU 61 multiplies the signal strength of the ranging waveform data of the kth adjacent azimuth area by the cumulative coefficient W(k). Hereinafter, the data obtained by multiplying the signal strength of the ranging waveform data by the cumulative coefficient is referred to as coefficient-multiplied waveform data.

[0117] In S280, the CPU 61 accumulates the coefficient-multiplied waveform data of the target azimuth region and the first to eighth adjacent azimuth regions. Hereinafter, the data obtained by accumulating the coefficient-multiplied waveform data of the target azimuth region and the first to eighth adjacent azimuth regions is referred to as accumulated waveform data. Fig.21 This shows a case where the accumulated waveform data is obtained by multiplying the ranging waveform data of the target azimuth region and the first to eighth adjacent azimuth regions by an accumulation coefficient and accumulating the data.

[0118] Then, if Fig.17As shown, in S290, the CPU 61 uses the accumulated waveform data obtained in S280 to calculate the time from the irradiation of the light beam to the detection of the light beam by the light receiving element 31, thereby executing a distance measurement process to measure the distance to the object reflecting the light beam.

[0119] Next, in S300, CPU61 increments the row indication value m (i.e., adds 1). Then, in S310, CPU61 determines whether the row indication value m is greater than 12. Here, in the case where the row indication value m is less than 12, CPU61 moves to S250. On the other hand, in the case where the row indication value m is greater than 12, in S320, CPU61 increments the column indication value n. Then, in S330, CPU61 determines whether the column indication value n is greater than the end column indication value Nend. Here, in the case where the column indication value n is less than the end column indication value Nend, CPU61 moves to S230. On the other hand, in the case where the column indication value n is greater than the end column indication value Nend, CPU61 ends the cumulative ranging process.

[0120] The optical radar device 1 configured in this manner includes a light projecting unit 10 , a scanning unit 20 , a light receiving unit 30 , and a control unit 3 .

[0121] The light projecting unit 10 and the scanning unit 20 irradiate laser light, and the light receiving unit 30 detects the reflected laser light.

[0122] The control unit 3 calculates a noise value associated with the amount of background light from the orientation area OR(i, j) based on the detection result of the light receiving unit 30 for each of the plurality of orientation areas OR(i, j) formed by dividing the light irradiation area Ri.

[0123] The control unit 3 sequentially selects one orientation region OR(i, j) from among the plurality of orientation regions OR(i, j) as a target orientation region.

[0124] The control unit 3 calculates the cumulative coefficient of the target azimuth region and each of the plurality of adjacent azimuth regions in such a manner that there is a negative correlation between the difference between the noise value of the adjacent azimuth region and the noise value of the target azimuth region. In addition, the so-called "negative correlation with the difference" includes not only the case where the cumulative coefficient decreases continuously as the difference increases, but also the case where the cumulative coefficient decreases step by step as the difference increases.

[0125] The control unit 3 generates distance measurement waveform data indicating a temporal change in signal intensity from the time when the laser beam is irradiated to the time when a preset distance measurement period elapses, for each of the plurality of azimuth regions OR(i, j).

[0126] The control unit 3 generates coefficient-multiplied waveform data by multiplying the distance measurement waveform data of each of the target azimuth region and the plurality of adjacent azimuth regions by the corresponding integration coefficient.

[0127] The control unit 3 generates cumulative waveform data by accumulating the coefficient-multiplied waveform data of the target azimuth region and a plurality of adjacent azimuth regions.

[0128] The control unit 3 measures the distance to the object reflecting the laser light using the generated accumulated waveform data.

[0129] In this way, the optical radar device 1 accumulates coefficient-multiplied waveform data of the target azimuth region and multiple adjacent azimuth regions in order to measure the distance to an object existing in the azimuth corresponding to the target azimuth region, thereby reducing randomly generated noise in the accumulated waveform data.

[0130] Furthermore, the optical radar device 1 calculates the cumulative coefficient in a manner that has a negative correlation with the difference between the noise value of the adjacent azimuth area and the noise value of the target azimuth area, and generates the coefficient-times waveform data by multiplying the ranging waveform data by the corresponding cumulative coefficient. Thus, when the amount of background light in the adjacent azimuth area is greater than the amount of background light in the target azimuth area, the optical radar device 1 can reduce the contribution of the ranging waveform data of the adjacent azimuth area in the accumulated waveform data. Therefore, when the amount of background light in the adjacent azimuth area is greater than the amount of background light in the target azimuth area, the optical radar device 1 can suppress the occurrence of a situation where the noise of the accumulated waveform data is greater than the noise of the ranging waveform data of the target azimuth area, and the noise can be further reduced in the accumulated waveform data.

[0131] As described above, the optical radar device 1 can improve the detection sensitivity of the reflected laser light detected by the light receiving unit 30 .

[0132] In addition, the control unit 3 calculates the omnidirectional standard deviation Var related to the standard deviation of the amount of background light in the entire light irradiation area Ri. Moreover, when the omnidirectional standard deviation Var is less than the preset distance determination value J1, the control unit 3 prohibits the execution of the processing of S220 to S330. That is, the optical radar device 1 can prohibit the generation of cumulative waveform data in a situation where the background light is small, such as at night and in a tunnel, and the accumulation coefficient of the adjacent azimuth area cannot be properly calculated. Thereby, the control unit 3 can suppress the reduction of the measurement accuracy of the distance to the object reflecting the laser.

[0133] In addition, the control unit 3 generates background light waveform data indicating the time change of the signal intensity in the background light acquisition period set not to overlap with the distance measurement period for each of the plurality of azimuth regions OR (i, j) based on the detection result of the light receiving unit 30. Furthermore, the control unit 3 performs filtering processing on the background light waveform data for each of the plurality of azimuth regions OR (i, j). Furthermore, the control unit 3 calculates the noise value using the background light waveform data on which the filtering processing is performed for each of the plurality of azimuth regions OR (i, j).

[0134] Thus, since the optical radar device 1 can suppress the noise of the background light in the background light waveform data, it is possible to further improve the detection sensitivity of the reflected laser light by the light receiving unit 30 .

[0135] In addition, the control unit 3 calculates the noise value based on the detection result of the light receiving unit 30 before the start of the ranging period. Therefore, since the optical radar device 1 can detect background light through the light receiving unit 30 without providing a sensor for detecting background light, the structure of the optical radar device 1 can be simplified.

[0136] In the above-described embodiment, the optical radar device 1 corresponds to the distance measuring device, the light projecting unit 10 and the scanning unit 20 correspond to the irradiating unit, the light receiving unit 30 corresponds to the light detecting unit, and S90 corresponds to the processing as the background light calculating unit.

[0137] In addition, S220, S240, S250, S300~S330 are equivalent to the processing as the object direction selection unit, S260 is equivalent to the processing as the coefficient calculation unit, S20, S110~S140 are equivalent to the processing as the distance measurement waveform generation unit, and S270 is equivalent to the processing as the multiple waveform generation unit.

[0138] In addition, S280 corresponds to the processing as the cumulative waveform generating unit, and S290 corresponds to the processing as the measuring unit.

[0139] In addition, the noise value corresponds to the background light amount parameter, the adjacent azimuth area corresponds to the peripheral azimuth area, and the signal intensity corresponds to the light detection parameter.

[0140] In addition, S100 corresponds to the processing as a standard deviation calculation unit, S210 corresponds to the processing as a deviation prohibition unit, the omnidirectional standard deviation Var corresponds to the standard deviation parameter, and the distance measurement determination value J1 corresponds to the deviation determination value.

[0141] In addition, S10 to S50 and S70 correspond to the processing as a background light waveform generating unit, and S80 corresponds to the processing as a filter processing unit.

[0142] (Second Embodiment)

[0143] Hereinafter, a second embodiment of the present invention will be described based on the drawings. In the second embodiment, the parts different from the first embodiment will be described. The same reference numerals are given to the common structures.

[0144] The optical radar device 1 of the second embodiment is different from the first embodiment in that the cumulative ranging process is changed.

[0145] The cumulative distance measurement process of the second embodiment is different from that of the first embodiment in that the process of S210 is omitted and the process of S212 is added.

[0146] That is, if the cumulative distance measurement process of the second embodiment is executed, Fig. 22 As shown, first in S212, the CPU 61 determines whether the vehicle speed Vv indicated by the latest vehicle speed detection signal obtained from the vehicle speed sensor 71 is greater than a preset distance determination value J2 (in this embodiment, for example, 60 km / h). Here, when the vehicle speed Vv is less than the distance determination value J2, the CPU 61 ends the cumulative distance measurement process. On the other hand, when the vehicle speed Vv is greater than the distance determination value J2, the CPU 61 moves to S220.

[0147] In the optical radar device 1 configured as above, the control unit 3 determines whether the vehicle speed Vv of the host vehicle is less than or equal to the ranging judgment value J2. Furthermore, when it is determined that the vehicle speed Vv is less than or equal to the ranging judgment value J2, the control unit 3 prohibits the execution of the processing of S220 to S330. That is, the optical radar device 1 generates the accumulated waveform data only when the vehicle is traveling at a high speed.

[0148] Thus, in a situation where it is necessary to measure the distance to a complex and small structure (e.g., a roadside object such as a guardrail or a pedestrian) near the vehicle, the optical radar device 1 can prohibit the measurement of the distance based on the accumulated waveform data. In addition, for a complex and small structure near the vehicle, there is a situation where the accumulation coefficient of the adjacent azimuth area cannot be properly calculated. Therefore, the optical radar device 1 can suppress the reduction in the measurement accuracy when measuring the distance to an object near the vehicle.

[0149] In the above-described embodiment, S212 corresponds to the vehicle speed determination unit and the vehicle speed prohibition unit, the vehicle speed Vv corresponds to the running speed, and the distance measurement determination value J2 corresponds to the vehicle speed determination value.

[0150] (Third Embodiment)

[0151] Hereinafter, a third embodiment of the present invention will be described based on the drawings. In the third embodiment, the parts different from the first embodiment will be described. The same reference numerals are given to the common structures.

[0152] The optical radar device 1 of the third embodiment is different from the first embodiment in that the cumulative ranging process is changed.

[0153] The cumulative distance measurement process of the third embodiment is different from that of the first embodiment in that the process of S210 is omitted and the processes of S214, S216, and S218 are added.

[0154] That is, if the cumulative distance measurement process of the third embodiment is executed, Fig.23 As shown, first in S214, the CPU 61 acquires image data from the front camera 72. Next, in S216, the CPU 61 detects the left and right boundary positions of the lane in which the host vehicle is traveling (hereinafter, the host vehicle traveling lane) by performing image recognition processing using the image data acquired in S214. For example, the boundary position of the host vehicle traveling lane can be detected by recognizing the white line of the lane using image recognition processing.

[0155] Then, in S218, the CPU 61 sets the column indication value n based on the left boundary position in the lane where the vehicle is traveling, and sets the end column indication value Nend based on the right boundary position in the lane where the vehicle is traveling, and moves to S230. Specifically, the CPU 61 sets the column indication value n by referring to, for example, a left setting map in which a correspondence relationship between the left boundary position and the column indication value n is pre-set. In addition, the CPU 61 sets the end column indication value Nend by referring to, for example, a right setting map in which a correspondence relationship between the right boundary position and the end column indication value Nend is pre-set.

[0156] In the optical radar device 1 configured as above, the control unit 3 detects the position of the driving lane in which the host vehicle is traveling. Furthermore, the control unit 3 selects the azimuth area OR(i, j) in which the driving lane is arranged among the plurality of azimuth areas OR(i, j) as the target azimuth area. Thus, the optical radar device 1 can reduce the number of target azimuth areas for generating accumulated waveform data, and can reduce the processing load of the control unit 3.

[0157] In the above-described embodiment, S214 and S216 correspond to the processing of the lane detection unit, and S218, S240, S250, and S300 to S330 correspond to the processing of the target direction selection unit.

[0158] (Fourth Embodiment)

[0159] Next, the fourth embodiment of the present invention and the attached Figure 1 In the fourth embodiment, the parts different from the first embodiment are described. The same reference numerals are given to the common structures.

[0160] The optical radar device 1 of the fourth embodiment is different from the first embodiment in that the cumulative ranging process is changed.

[0161] The cumulative distance measurement process of the fourth embodiment is different from the first embodiment in that the processes of S210 and S220 are omitted and the processes of S222 and S224 are added.

[0162] That is, if the cumulative distance measurement process of the fourth embodiment is executed, Fig.24 As shown, first in S222 , the CPU 61 acquires road map data indicating the shape of the road ahead of the host vehicle from the navigation device 73 .

[0163] Then, in S224, CPU61 sets the column indication value n and the end column indication value Nend based on the road shape represented by the road map data obtained in S222. Specifically, when the road in front of the vehicle is straight, CPU61 sets the column indication value n and the end column indication value Nend in such a way that the average values ​​of the column indication value n and the end column indication value Nend correspond to the scanning angle of 0°. Moreover, when the road in front of the vehicle turns to the left, the greater the degree of turning to the left, the more CPU61 reduces the column indication value n and the end column indication value Nend. In addition, when the road in front of the vehicle turns to the right, the greater the degree of turning to the right, the more CPU61 increases the column indication value n and the end column indication value Nend.

[0164] In the optical radar device 1 configured as above, the control unit 3 acquires road map data indicating the shape of the road in front of the vehicle. Furthermore, the control unit 3 selects, from among the plurality of orientation areas OR(i, j), an orientation area OR(i, j) where the road in front of the vehicle is arranged as a target orientation area based on the acquired road map data. Thus, the optical radar device 1 can reduce the number of target orientation areas for generating accumulated waveform data, and can reduce the processing load of the control unit 3.

[0165] In the above-described embodiment, S222 corresponds to the process of the road shape acquisition unit, and S224, S240, S250, and S300 to S330 correspond to the process of the target direction selection unit.

[0166] (Fifth Embodiment)

[0167] Hereinafter, a fifth embodiment of the present invention will be described based on the drawings. In the fifth embodiment, the parts different from the first embodiment will be described. The same reference numerals are given to the common structures.

[0168] The optical radar device 1 of the fifth embodiment is different from the first embodiment in that the cumulative ranging process is changed.

[0169] The cumulative distance measurement process of the fifth embodiment is different from the first embodiment in that the process of S252 is added.

[0170] That is, Fig.25 As shown, if the processing of S250 is completed, then in S252, CPU61 sets the standard deviation σ of the normal distribution represented by the above formula (1) based on the noise value of the object orientation area calculated in S90, and moves to S260. In the present embodiment, specifically, when the noise value of the object orientation area is below a preset standard deviation judgment value, CPU61 sets the standard deviation σ to a preset low light standard deviation σ1. In addition, when the noise value of the object orientation area is greater than the standard deviation judgment value, CPU61 sets the standard deviation σ to a preset high light standard deviation σ2. In addition, the low light standard deviation σ1 is smaller than the high light standard deviation σ2. In the present embodiment, the low light standard deviation σ1 is Fig.26 The standard deviation of the normal distribution ND1 is shown. The standard deviation of the high light intensity σ2 is Fig.26 The standard deviation of the normal distribution ND2 is shown.

[0171] In the optical radar device 1 configured as above, the control unit 3 calculates the cumulative coefficient for each of the plurality of azimuth regions OR (i, j) in such a manner that the cumulative coefficient has a positive correlation with the amount of background light in the target azimuth region. In addition, the so-called "having a positive correlation with the amount of background light" includes not only that the cumulative coefficient increases continuously as the amount of background light increases, but also that the cumulative coefficient increases in stages as the amount of background light increases.

[0172] That is, when a vehicle is present in the target direction area, the accumulation coefficient decreases for a vehicle color with less background light (eg, black), and increases for a vehicle color with more background light (eg, white).

[0173] Therefore, the optical radar device 1 can suppress the accumulation of inappropriate coefficient-multiplied waveform data in the case of a vehicle color with a small amount of background light, and can improve the detection sensitivity of the light receiving unit 30 by accumulating coefficient-multiplied waveform data in the case of a vehicle color with a large amount of background light.

[0174] In the above-described embodiment, S252 and S260 correspond to the processing as a coefficient calculation unit.

[0175] As mentioned above, although one embodiment of the present invention has been described, the present invention is not limited to the above-mentioned embodiment, and can be implemented with various modifications.

[0176] [Modification 1]

[0177] For example, in the above embodiment, a method of accumulating coefficient-multiplied waveform data of an azimuth region adjacent to the target azimuth region (i.e., an azimuth region that is one column or one row away from the target azimuth region) is shown. However, coefficient-multiplied waveform data of an azimuth region that is one column to multiple columns or one row to multiple rows away from the target azimuth region may also be accumulated.

[0178] [Modification 2]

[0179] In the above-mentioned embodiment, a method of performing filtering using a bidirectional filter is shown, but the present invention is not limited to the bidirectional filter, and any filter may be used as long as it maintains the edge of a waveform and smoothes it.

[0180] [Variation 3]

[0181] In the second embodiment, the mode of prohibiting accumulation when the vehicle speed Vv is less than the distance determination value J2 is shown. However, the control unit 3 may also determine whether the vehicle is traveling on a highway based on information from the navigation device 73, and prohibit accumulation when it is determined that the vehicle is traveling on a highway. That is, when it is determined that the vehicle is traveling on a highway, the control unit 3 determines that the vehicle speed Vv exceeds 80 km / h.

[0182] [Variation 4]

[0183] In the first embodiment described above, the omnidirectional standard deviation Var is calculated using the detection result of the light receiving unit 30. However, the omnidirectional standard deviation Var may be calculated based on image data acquired from a camera that captures the surroundings of the vehicle.

[0184] [Variation 5]

[0185] In the fifth embodiment, the standard deviation σ of the normal distribution shown in the above equation (1) is set stepwise according to the noise value of the target direction region. However, the standard deviation σ may be changed continuously according to the noise value of the target direction region.

[0186] The control unit 3 and the method thereof described in the present invention may also be implemented by a special-purpose computer, which is provided by a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit 3 and the method thereof described in the present invention may also be implemented by a special-purpose computer provided by a processor constituted by one or more special-purpose hardware logic circuits. Alternatively, the control unit 3 and the method thereof described in the present invention may also be implemented by one or more special-purpose computers, which are composed of a combination of a processor and a memory programmed to execute one or more functions, and a processor constituted by one or more hardware logic circuits. In addition, the computer program may also be stored as an instruction executed by a computer in a computer-readable non-transitional tangible recording medium. The method for realizing the functions of each part included in the control unit 3 does not necessarily need to include software, and one or more hardware may be used to realize all of its functions.

[0187] Multiple functions of one component in the above-mentioned embodiment can be realized by multiple components, or a function of one component can be realized by multiple components. In addition, multiple functions of multiple components can be realized by one component, or a function realized by multiple components can be realized by one component. In addition, a part of the structure of the above-mentioned embodiment can also be omitted. In addition, at least a part of the structure of the above-mentioned embodiment can also be added to or replaced with the structure of other above-mentioned embodiments.

[0188] In addition to the above-mentioned optical radar device 1, the present invention can also be implemented in various ways such as a system with the optical radar device 1 as a constituent element, a program for making a computer function as the optical radar device 1, a non-transitional physical recording medium such as a semiconductor memory recording the program, a ranging method, etc.

Claims

1. A distance measuring device, comprising: an irradiation portion configured to irradiate light; a light detection unit configured to detect the reflected light; a background light calculation unit configured to calculate, for each of a plurality of azimuth areas formed by dividing the light irradiation area irradiated with the light, a background light amount parameter associated with the amount of background light from the azimuth area based on the detection result of the light detection unit; A target orientation selection unit is configured to sequentially select one of the plurality of orientation areas as a target orientation area; a coefficient calculation unit configured to set the above-mentioned azimuth area arranged around the above-mentioned object azimuth area selected by the above-mentioned object azimuth selection unit as a peripheral azimuth area, and calculate the cumulative coefficient of the above-mentioned object azimuth area and each area of ​​the plurality of the above-mentioned peripheral azimuth areas in a manner that has a negative correlation with the difference between the above-mentioned background light amount parameter of the above-mentioned peripheral azimuth area and the above-mentioned background light amount parameter of the above-mentioned object azimuth area; a distance measurement waveform generating unit configured to generate, for each of the plurality of azimuth regions, distance measurement waveform data representing a time change of the light detection parameter from irradiation of the light to elapse of a preset distance measurement period, using a parameter representing a detection result of the light detection unit as a light detection parameter; a multiple waveform generating unit configured to generate coefficient-multiplied waveform data by multiplying the distance measurement waveform data of the target azimuth region and the plurality of peripheral azimuth regions by the corresponding accumulation coefficient; a cumulative waveform generating unit configured to generate cumulative waveform data by accumulating the coefficient-multiplied waveform data of the target azimuth region and the plurality of peripheral azimuth regions; as well as The measuring unit is configured to measure a distance to an object reflecting the light using the cumulative waveform data generated by the cumulative waveform generating unit.

2. The distance measuring device according to claim 1, wherein: have: a standard deviation calculation unit configured to calculate a standard deviation parameter associated with a standard deviation of the amount of the background light in the entire light irradiation area; and The deviation prohibition unit is configured to prohibit execution of at least the processing by the background light calculation unit, the object direction selection unit, and the coefficient calculation unit when the standard deviation parameter is equal to or less than a preset deviation determination value.

3. The distance measuring device according to claim 1, wherein: The coefficient calculation unit calculates the integration coefficient for each of the plurality of peripheral azimuth areas so as to have a positive correlation with the amount of the background light in the target azimuth area.

4. The distance measuring device according to any one of claims 1 to 3, wherein: have: A background light waveform generating unit is configured to generate background light waveform data representing a time change of the light detection parameter during a background light acquisition period for each of the plurality of azimuth areas based on a detection result of the light detection unit, wherein the background light acquisition period is set not to overlap with the distance measurement period; and The filter processing unit is configured to perform a filter process on the background light waveform data for each of the plurality of azimuth areas. The background light calculation unit calculates the background light amount parameter for each of the plurality of azimuth areas using the background light waveform data on which the filtering process has been performed by the filtering unit.

5. The distance measuring device according to any one of claims 1 to 3, wherein: The background light calculation unit calculates the background light amount parameter based on a detection result of the light detection unit before the start of the distance measurement period.

6. The distance measuring device according to any one of claims 1 to 3, wherein: The distance measuring device is mounted on a vehicle. The above-mentioned distance measuring device has: a vehicle speed determination unit configured to determine whether the running speed of the vehicle is equal to or less than a preset vehicle speed determination value; and The vehicle speed prohibition unit is configured to prohibit execution of at least processing by the background light calculation unit, the object direction selection unit, and the coefficient calculation unit when the vehicle speed determination unit determines that the traveling speed is equal to or less than the vehicle speed determination value.

7. The distance measuring device according to any one of claims 1 to 3, wherein: The distance measuring device is mounted on a vehicle. The distance measuring device includes a lane detection unit configured to detect the position of a lane in which the vehicle is traveling. The target direction selection unit selects the direction area in which the driving lane is arranged from among the plurality of direction areas as the target direction area based on the detection result of the lane detection unit.

8. The distance measuring device according to any one of claims 1 to 3, wherein: The distance measuring device is mounted on a vehicle. The distance measuring device includes a road shape acquiring unit configured to acquire road map data indicating the shape of the road around the vehicle. The target direction selection unit selects, based on the acquired road map data, the direction area in which the road around the vehicle is arranged among the plurality of direction areas as the target direction area.

Images