JP6631228B2 - Perimeter monitoring device - Google Patents

Description

  The present invention relates to a technique for monitoring a side of a vehicle.

  Patent Literature 1 discloses a light receiving unit configured to include a light emitting unit that emits a laser beam to a predetermined monitoring area and a plurality of light receiving elements arranged in a horizontal direction, wherein each light receiving element receives reflected light coming from a different direction. And a peripheral monitoring device that detects an object existing in a monitoring area based on a reception signal obtained from a light receiving unit.

JP 2014-190812 A

  When this peripheral monitoring device is used as a technology for realizing automatic driving of a vehicle, the side of the vehicle is monitored in order to cause the peripheral monitoring device to detect an interrupting vehicle or the like that interrupts in front of the vehicle. Can be set to In this case, it is required that a lane adjacent to at least the traveling lane in which the own vehicle is traveling be regarded as an adjacent lane and that an adjacent vehicle that is a vehicle traveling in the adjacent lane be detected with high accuracy.

  However, when the target is an adjacent vehicle having a vehicle body of a color (for example, black) having a low reflection intensity, strong reflection intensity is not obtained from the vehicle body portion, and strong reflection intensity is obtained only in a portion where the tire wheel exists. For this reason, the reception signal obtained by scanning the monitoring area in the horizontal direction has a pulse-like signal waveform, which is similar to the case where the target is a roadside reflector which is a reflector installed at the roadside. Signal waveform. That is, it is difficult to distinguish an adjacent vehicle having a vehicle body of a color (for example, black) having a low reflection intensity from the roadside reflector from the received waveform, which causes a problem of erroneous detection.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a technique for improving the detection accuracy of another vehicle existing on the side of a vehicle.

  The surroundings monitoring device of the present invention is mounted on a vehicle and used, and includes a light emitting unit, a light receiving unit, and a signal processing unit. The light emitting unit emits light to a monitoring area set on a side of the vehicle. The light receiving unit receives the reflected light from the object that reflects the light projected by the light emitting unit for each of a plurality of horizontal divided regions obtained by dividing the monitoring region in the horizontal direction. The signal processing unit obtains the position of the object reflecting light from the light receiving signal obtained from the light receiving unit. Here, a vehicle traveling in a lane adjacent to the traveling lane of the own vehicle which is a vehicle equipped with the periphery monitoring device is defined as an adjacent vehicle. The monitoring area is configured by a plurality of vertical divided areas divided in the height direction so as to include a part of the adjacent vehicle when the adjacent vehicle exists. Then, the light receiving unit generates a light receiving signal for each vertical division region.

  According to such a configuration, each of the plurality of reception signals obtained from each of the vertical divided areas has a unique pattern, reflecting the structure of the object to be detected and the like. Therefore, the detection accuracy can be improved as compared with the case where the presence or absence of an object to be detected is determined based on one type of received signal.

  Note that the reference numerals in parentheses described in this column and in the claims indicate the correspondence with specific means described in the embodiment described below as one aspect, and denote the technical scope of the present invention. There is no limitation.

FIG. 2 is a block diagram illustrating a configuration of a peripheral monitoring device. FIG. 3 is an explanatory diagram showing a configuration and a positional relationship of a light emitting unit and a light receiving unit, and a relationship with a monitoring region and a vertical division region. FIG. 4 is an explanatory diagram regarding setting of a monitoring area. FIG. 4 is an explanatory diagram showing the configuration of the photodiode array when the light receiving unit is viewed from below and the operation of the light receiving lens. FIG. 4 is an explanatory diagram illustrating a connection state of a power supply line and a signal line of a light receiving unit. FIG. 4 is a timing chart illustrating an operation example of a light emitting unit and a light receiving unit. It is a flowchart which shows the content of the vehicle determination function which a signal processing part implement | achieves. It is explanatory drawing which shows the situation which is the premise of an operation example. FIG. 7 is an explanatory diagram showing a light reception waveform for each target and a light reception waveform in a comparative example. It is a graph which shows the area of the light-receiving surface of a light-receiving element, a noise floor, and the relationship with detection capability. It is an explanatory view showing the composition etc. of the light sensing portion in a 2nd embodiment. It is explanatory drawing which shows the structure of a photodiode array when the light receiving part in 2nd Embodiment is seen from below, and the effect | action of a light receiving lens. It is explanatory drawing which shows the connection state of the power supply line and signal line of the light receiving part in 2nd Embodiment. FIG. 11 is a timing chart illustrating an operation example of a light emitting unit and a light receiving unit according to the second embodiment. It is an explanatory view showing another example of composition of a transmitting part.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.
[1. First Embodiment]
[1-1. Constitution]
The periphery monitoring device 1 is used, for example, mounted on a vehicle such as a passenger car (hereinafter also referred to as “own vehicle”). As an example, it is conceivable that the periphery monitoring device 1 is installed near a position at the height near the upper end of the tire on the left and right side surfaces of the vehicle, and each of them detects an object existing on the right side or left side of the vehicle. The periphery monitoring device 1 is not limited to this position, and may be set at an arbitrary position (height). The object to be detected includes at least an adjacent vehicle that is a vehicle traveling in a lane adjacent to a traveling lane in which the host vehicle travels.

  The peripheral monitoring device 1 includes a signal processing unit 2, a light emitting unit 3, and a light receiving unit 4, as shown in FIG. The light emitting unit 3 periodically irradiates the laser beam and notifies the signal processing unit 2 of the irradiation timing. The light receiving unit 4 receives the reflected light from the object reflecting the laser light emitted by the light emitting unit 3 and notifies the signal processing unit 2 of the light receiving timing. The signal processing unit 2 detects an object reflecting the laser beam from the irradiation timing and the light receiving timing, and obtains a distance from the object.

  The light emitting section 3 includes a pair of light emitting elements 31 and 32 and a light projecting lens 33 as shown in FIG. The pair of light emitting elements 31 and 32 are constituted by a pair of laser diodes arranged in the height direction of the vehicle. Hereinafter, the light emitting element 31 located on the upper side is referred to as LD1, and the light emitting element 32 located on the lower side is referred to as LD2. The light projecting lens 33 is arranged so as to stop the laser light output from the LD 1 and project the light downward, and to stop the laser light output from the LD 2 and project the light upward. . The area where the laser light output from the LD 1 is projected via the light projecting lens 33 is referred to as a first divided area A1, and the area where the laser light output from the LD 2 is projected via the light projecting lens 33 is referred to as a second area. It is called a divided area A2. The whole of the first divided area A1 and the second divided area is referred to as a monitoring area. That is, the first divided area A1 and the second divided area are obtained by dividing the monitoring area into a plurality of parts in the vertical direction, and are also referred to as vertical divided areas. Specifically, as shown in FIG. 3, a region below the vicinity of the upper end of the tire of an adjacent vehicle existing at a distance of about 2 to 5 m on the side of the own vehicle is a first divided region A1, and the region is closer to the upper end of the tire. The upper region is set to be the second divided region A2.

  Returning to FIG. 2, the light receiving unit 4 includes a pair of light receiving element arrays 41 and 42 and a light receiving lens 43. The light receiving unit 4 is provided below the light emitting unit 3 and is arranged closer to the center of the vehicle body than the light emitting unit 3 is. The pair of light receiving element arrays 41 and 42 are arranged in the height direction of the vehicle. Hereinafter, the light receiving element array 41 located on the upper side is referred to as PDA1, and the light receiving element array 42 located on the lower side is referred to as PDA2. The light receiving lens 43 is arranged so that the reflected wave arriving from the direction of the first divided area A1 is focused and condensed on the PDA1 and the reflected wave arriving from the direction of the second divided area A2 is condensed on the PDA2. Have been. Since PDA1 and PDA2 have the same configuration, unless it is particularly necessary to distinguish them, they are denoted as PDAi with i = 1,2.

  As shown in FIG. 4, the PDAi includes ten light receiving elements arranged in a line in the horizontal direction. Reflected light is incident on the PDAi from an angle range of about ± 20 ° with the front direction of the PDAi, that is, the rightward or leftward direction of the vehicle as 0 °. In other words, each of the ten light receiving elements constituting the LDAi receives reflected light from an angle range of about 4 degrees through the light receiving lens 43. The light receiving range of each of these light receiving elements is called a horizontal division area. Note that the number of light receiving elements constituting the PDAi is not limited to ten, but can be set to any number.

  The light receiving unit 4 includes switches 44 and 45, as shown in FIG. The switch 44 selects one of PDA1 and PDA2 and selectively supplies power according to the switching signal Sx from the signal processing unit 2. The switch 45 similarly selects the side of the PDA1 or PDA2 to which power is supplied according to the switching signal Sx, and supplies the reception signal R output from the selected PDAi to the signal processing unit 2. That is, the PDAi is configured to operate alternatively, and to supply power only to the operating one.

  The signal processing unit 2 is mainly configured by a known microcomputer having a CPU 21 and a semiconductor memory (hereinafter, a memory 22) such as a RAM, a ROM, and a flash memory. Various functions of the signal processing unit 2 are realized by the CPU 21 executing a program stored in a non-transitional substantial recording medium. In this example, the memory 22 corresponds to a non-transitional substantive recording medium storing a program. In addition, by executing this program, a method corresponding to the program is executed. The number of microcomputers constituting the signal processing unit 2 may be one or more.

  The signal processing unit 2 includes, as functions realized by the CPU 21 executing the program, a distance calculation function for calculating a distance to an object reflecting a radar wave, and a vehicle for determining whether the detected object is a vehicle. At least a determination function. The method of realizing these functions of the signal processing unit 2 is not limited to software, and some or all of the elements may be realized using hardware combining logic circuits, analog circuits, and the like.

[1-2. processing]
Among the functions of the signal processing unit 2, in the distance calculation function, the LD1 and LD2 forming the light emitting unit 3 and the PDA1 and PDA2 forming the light receiving unit 4 are operated at a preset timing, and the laser light by the LD1 and LD2 is operated. The distance to the object that reflected the laser light is determined from the time difference from the irradiation timing of the laser beam to the reception timing of the reflected light by the PDA1 and PDA2. At this time, as shown in FIG. 6, the signal processing unit 2 outputs the switching signal Sx so that the set of LD1 and PDA1 and the set of LD2 and PDA2 operate alternately in a time-sharing manner.

  Next, a process executed by the signal processing unit 2 to realize the vehicle determination function will be described with reference to the flowchart of FIG. This process is started every time a reception signal from both PDA1 and PDA2 is obtained.

In the following, it is assumed that the number of light receiving elements constituting PDAi is Np, and the output of each light receiving element is described as Oi (0), Oi (1),..., Oi (Np-1).
When this process is started, the CPU 21 first initializes, in S110, a parameter j used as an identifier for designating a light receiving element, and eventually an identifier for designating a horizontal divided area, to zero.

In subsequent S120, it is determined whether or not j is equal to or larger than Np. If j ≧ Np, the process proceeds to S190, while if j <Np, the process proceeds to S130.
In S130, it is determined whether or not the output O1 (j) of the j-th light receiving element of the PDA1 is equal to or higher than a preset high threshold value Sh. If O1 (j) ≧ Sh, the process proceeds to S140, and if O1 (j) <Sh, the process proceeds to S180.

  In S140, it is determined whether or not the output O2 (j) of the j-th light receiving element of the PDA 2 is equal to or higher than the high threshold Sh. If O2 (j) ≧ Sh, the process proceeds to S150. If O2 (j) <Sh, the process proceeds to S160.

In S150, it is determined that a vehicle candidate exists in the horizontal divided area corresponding to the j-th light receiving element, and the process proceeds to S180.
In S160, it is determined whether or not the output O2 (j) of the j-th light receiving element of the PDA 2 is equal to or greater than a low threshold Sl set to a value lower than the high threshold Sh. If O2 (j) ≧ S1, the process proceeds to S170, and if O2 (j) <S1, the process proceeds to S180.

In S170, it is determined that the vehicle wheel exists in the horizontal divided area corresponding to the i-th light receiving element, and the process proceeds to S180.
In S180, the parameter j is incremented, that is, the value is increased by 1, and the process returns to S120.

  In other words, it is determined that a vehicle exists in the horizontal divisional area in which both the areas A1 and A2 are equal to or higher than the high threshold Sh. It is determined that the tire wheel of the vehicle exists, and otherwise, the determination is suspended. The high threshold value Sh detects reflected light from a highly reflective object such as a vehicle body having a large reflection intensity (for example, white) or a roadside reflector which is a reflection plate installed at a roadside, but has a low reflection intensity. The size is set such that reflected light from a low-reflection object such as a color (for example, black) vehicle body is not detected. Further, the low threshold value Sl is set to such a size that the reflected light from the tire wheel can be received.

In S190, from the determination results in S150 and S170, the presence / absence of an adjacent vehicle which is a vehicle traveling in the adjacent lane, the position of the adjacent vehicle, and the like are comprehensively determined, and this processing ends.
[1-3. Operation example]
Next, an operation example of the periphery monitoring device 1 will be described.

  Here, as shown in FIG. 8, a description will be given of a result of performing detection with the roadside reflector T1 and the vehicle T2 installed at the roadside as targets. It is assumed that most of the roadside reflector T1 is located in the second divided area A2. Further, the vehicle T2 has a vehicle body of a color (for example, black) with a small reflection intensity, in which the entire tire is located in the first divided area A1. Note that the first divided area A1 and the second divided area A2 are not clearly divided as shown in the figure, and a portion where the two areas A1 and A2 overlap is present near the boundary.

  As shown in FIG. 9, when the roadside reflector T1 is the target, in the second divided area A2, a large peak equal to or higher than the high threshold Sh is detected in the direction in which the roadside reflector T1 exists (that is, the horizontal divided area). Is done. In the first divided area A1, a small peak less than the high threshold Sh is detected in the direction in which the roadside reflector T1 exists due to the influence of the reflected light from near the lower end of the roadside reflector T1.

  On the other hand, when the vehicle T2 is a target, since the vehicle body is a color (for example, black) having a small reflection intensity, both the first divided area A1 and the second divided area A2 have the low threshold value Sl in most directions. The received light intensity is below the level. However, in the first divided area A1, a large peak equal to or higher than the high threshold value Sh is detected in the azimuth where the tire wheel exists. In the azimuth in which there is, a peak that is less than the high threshold Sh but is equal to or greater than the low threshold Sl is detected.

  In the case where the vehicle body of the vehicle T2 is a color having a large reflection intensity (for example, white), although not shown, in the second divided region A2, the light reception intensity equal to or higher than the high threshold Sh is detected in all directions, and the second divided region A2 is detected. In one divided area A1, light reception intensity equal to or higher than the high threshold value Sh is detected except for the direction in which the rubber portion of the tire exists. That is, when there is a vehicle T2 having a vehicle body of a color (for example, white) having a large reflection intensity, in most cases, the light reception intensity equal to or higher than the high threshold Sh is detected in both the first divided region A1 and the second divided region A2. Will be.

  Here, a comparative example in which the first divided area A1 and the second divided area A2 are collectively detected as a single area, that is, in the case of the related art in which only one line is scanned when a lateral object is detected. Will be described. In this case, when the roadside reflector T1 is a target, a large peak equal to or higher than the high threshold Sh is detected in the direction in which the roadside reflector T1 exists. On the other hand, if the target is the vehicle T2 having a vehicle body of a color (for example, black) with a low vehicle reflection intensity, a large peak equal to or higher than the high threshold Sh is detected in the direction in which the tire wheel exists.

  While it is not possible to distinguish whether the peak is due to the roadside reflector T1 or the peak due to the tire wheels of the vehicle T2 from the received light waveform of the comparative example, the received light waveform obtained by the periphery monitoring device 1 clearly indicates both. You can see that there are some differences.

[1-4. effect]
According to the first embodiment described in detail above, the following effects can be obtained.
(1a) In the periphery monitoring device 1, the monitoring area is vertically divided into a first divided area A1 and a second divided area A2, and the first divided area A1 is a portion near a height at which a tire of an adjacent vehicle exists. The second divided area A2 detects a portion higher than the first divided area A1. Therefore, the received light waveform based on the received signals obtained from each of the divided areas A1 and A2 has a unique pattern, reflecting the structure of the object to be detected and the like. Therefore, when judging whether or not the object reflecting the laser light is a vehicle, the accuracy of the judgment, and hence the judgment of a specific object such as a vehicle, is compared with the prior art in which judgment is made based on a single received light waveform. Detection accuracy can be improved.

  (1b) In the periphery monitoring device 1, different PDAs 1 and 2 are used to receive reflected light from the first divided area A1 and the second divided area A2, respectively. For this reason, compared with the case where light is collectively received in the monitoring area, the light receiving element constituting the PDAi can use a light receiving element having a small light receiving surface. As a result, as shown in FIG. 10, the floor level of the received light noise is reduced, so that a smaller peak of the received light intensity can be detected, and the detection capability can be improved.

[2. Second Embodiment]
[2-1. Differences from First Embodiment]
Since the second embodiment has the same basic configuration as the first embodiment, the description of the common configuration will be omitted, and the description will focus on the differences. The same reference numerals as in the first embodiment denote the same components, and refer to the preceding description.

  In the first embodiment described above, the light receiving section 4 is configured using two light receiving element arrays 41 and 42 (that is, PDA1 and PDA2). On the other hand, the second embodiment is different from the first embodiment in that the light receiving unit 4a is configured using a single light receiving element array 46.

[2-2. Constitution]
As shown in FIG. 11, the light receiving unit 4a includes a single light receiving element array 46 instead of the pair of light receiving element arrays 41 and 42. Hereinafter, the light receiving element array 46 is referred to as a PDA. The PDA receives, via the light receiving lens 43, a reflected wave coming from the direction of the first divided region A1, and also receives a reflected wave coming from the direction of the second divided region A2.

  The PDA is configured similarly to the PDAi, as shown in FIG. However, in the following, a partial array composed of five light receiving elements for receiving reflected light coming from the range of -20 ° to 0 ° is a PDR, and five partial light receiving elements for receiving reflected light coming from the range of 0 ° to 20 °. Are referred to as PDL. The PDR and PDL are configured to receive power individually. The number of light receiving elements constituting the PDA is not limited to ten, but can be set to an arbitrary number. Further, the number of partial arrays is not limited to two, but may be three or more.

  Then, as shown in FIG. 13, the switches 44 and 45 select one of the partial arrays PDR and PDL instead of selecting one of the PDA1 and PDA2 according to the switching signal Sx, as shown in FIG. In addition, power is supplied alternatively, and the received signal R output from the selected partial array is supplied to the signal processing unit 2. In other words, the PDR and the PDL operate alternately, and power is supplied only to the operating one.

[2-3. processing]
Among the functions of the signal processing unit 2, in the distance calculation function, the LD1 and LD2 forming the light emitting unit 3 and the PDR and PDL forming the light receiving unit 4a are operated at a preset timing, and the laser light by the LD1 and LD2 is operated. The distance to the object reflecting the laser light is determined from the time difference from the irradiation timing of the laser beam to the timing of receiving the reflected light by the PDR and PDL. At this time, as shown in FIG. 14, the signal processing unit 2 outputs the switching signal Sx so that the PDR and the PDL are alternately operated in a time division manner. LD1 and LD2 control so that the operation state of LD1 and LD2 is alternately switched each time PDR and PDL operate once. That is, control is performed such that the received signals O (0) to O (9) from all the horizontal divided areas are obtained for each operation period of the LDi.

[2-3. effect]
According to the second embodiment described in detail above, the following effect is obtained in addition to the effect (1a) of the first embodiment described above.

  (2a) In the present embodiment, a single receiving element array PDA is divided into two partial arrays PDR and PDL, and when power is supplied to one partial array, power supply to the other partial array is stopped. ing. This reduces the floor level of the received light noise as compared with the case where power is constantly supplied to the entire PDA, so that a smaller peak of the received light intensity can be detected and the detection capability can be improved.

[3. Other Embodiments]
The embodiments for carrying out the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and can be implemented with various modifications.

  (3a) In the above embodiment, the monitoring area is divided into two in the vertical direction by configuring the light emitting unit 3 using the two light emitting elements 31 and 32 (that is, LD1 and LD2). However, the present invention is not limited to this. For example, as shown in FIG. 15, the light emitting unit 3a is configured by using three light emitting elements LD1 to LD3, and the monitoring area is divided into three vertically divided areas A1 to A3, or four or more light emitting elements. The device may be divided into four or more divided regions.

  (3b) In the first embodiment, power is alternately supplied to the two light receiving element arrays 41 and 42 (that is, PDA1 and PDA2) provided corresponding to the divided areas A1 and A2. This technique may be combined with the technique of the second embodiment to divide each PDAi into two or more partial arrays and to selectively supply power to one of the partial arrays to operate. Good.

  (3c) The function of one component in the above embodiment may be realized by a plurality of components, or one function may be realized by a plurality of components. Also, a plurality of functions of a plurality of components may be realized by one component, or one function realized by a plurality of components may be realized by one component. Further, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above-described embodiment may be added to or replaced by the configuration of another above-described embodiment. In addition, all aspects included in the technical idea specified only by the language described in the claims are embodiments of the present invention.

  (3c) In addition to the above-described peripheral monitoring device, a system including the peripheral monitoring device as a component, a program for causing a computer to function as a signal processing unit of the peripheral monitoring device, and a non-transition device such as a semiconductor memory storing the program. The present invention can also be realized in various forms, such as a recording medium, a method of detecting an adjacent vehicle, and the like.

  DESCRIPTION OF SYMBOLS 1 ... Perimeter monitoring device, 2 ... Signal processing part, 3, 3a ... Light emitting part, 4, 4a ... Light receiving part, 21 ... CPU, 22 ... Memory, 31, 32 ... Light emitting element, 33 ... Light emitting lens, 41, 42 , 46: light receiving element array, 43: light receiving lens, 44, 45: switch, A1: first divided area, A2: second divided area, LD1, LD2: light emitting element, PDA1, PDA2, PDA: receiving element array, PDR , PDL: partial array, T1: roadside reflector, T2: vehicle.

Claims (7)

A peripheral monitoring device (1) mounted on a vehicle for use,
A light emitting unit (3, 3a) for projecting light to a monitoring area set on a side of the vehicle;
A light receiving unit (4, 4a) for receiving reflected light from an object reflecting light emitted by the light emitting unit for each of a plurality of horizontal divided regions obtained by dividing the monitoring region in a horizontal direction;
A signal processing unit (2) for determining a position of an object reflecting the light from a light reception signal obtained from the light receiving unit;
With
A vehicle traveling in a lane adjacent to the traveling lane of the vehicle is an adjacent vehicle,
The monitoring area is configured by a plurality of vertical divided areas divided in the height direction so as to include a part of the adjacent vehicle when the adjacent vehicle is present,
The light-emitting unit includes a plurality of light-emitting elements for sequentially selecting any of the vertical divided regions and projecting light to the selected vertical divided region,
The periphery monitoring device, wherein the light receiving unit generates the light receiving signal for each of the vertical divided areas. The peripheral monitoring device according to claim 1,
A first divided area, which is one of the vertical divided areas, is set in a range including a tire of the adjacent vehicle, and a second divided area, which is another one of the vertical divided areas, is a reflection indicating a road edge. A peripheral monitoring device that is set in a range that includes a road-side reflector that is a plate. The periphery monitoring device according to claim 2, wherein
The signal processing unit, when the intensity of the received light signal obtained in the same horizontal divided region is equal to or greater than a predetermined threshold in both the first divided region and the second divided region, A peripheral monitoring device that determines that there is a vehicle inside. The peripheral monitoring device according to any one of claims 1 to 3 , wherein
A peripheral monitoring device, wherein the light receiving unit includes a light receiving element array (41, 42, 46) configured by a plurality of light receiving elements that receive light for each of the horizontal divided areas. The periphery monitoring device according to claim 4 , wherein
The periphery monitoring device, wherein the light receiving unit includes the light receiving element array (41, 42) for each of the vertical divided areas. The periphery monitoring device according to claim 5 , wherein
A power supply control unit that sequentially selects one of the light receiving element arrays, activates the selected light receiving element array, and stops power supply to the non-operating light receiving element array; A peripheral monitoring device further comprising: The peripheral monitoring device according to claim 5 or 6 , wherein:
The light receiving element array (46) is constituted by a plurality of partial arrays,
The light receiving unit further includes a power supply control unit (44) that sequentially selects any of the partial arrays, activates the selected partial array, and stops power supply to the inactive partial array. Monitoring device.