JP3838418B2 - Ranging device for vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionRoad surfaceThe present invention relates to an optical distance measuring device (radar) that can distinguish and distinguish reflected light from other vehicles and the like.
[0002]
[Prior art]
As is well known, when the road surface is wet due to rain or the like, the braking performance or the like of the vehicle is greatly reduced, and a slip accident is likely to occur. In addition, a radar for a vehicle (for example, a laser radar) is indispensable for a monitoring function of a preceding vehicle or the like and a function of automatically following a preceding vehicle that are becoming popular in recent years. In some cases, performance deteriorates due to rain or wet roads.
In particular, as shown in FIG. 5 (b), if there are water droplets (splash) that are rolled up and scattered from a wet road surface by a preceding vehicle 2 traveling in front of the host vehicle 1, the radar 3 mounted on the host vehicle 1 Since most of the irradiation light 4 is irregularly reflected by the water droplets, the maximum detection distance of the preceding vehicle or the like by the radar 3 is remarkably reduced. For example, in the normal time, a preceding vehicle 100 m ahead can be recognized, but 50 m ahead There is a risk that extreme performance degradation such as recognition of only the preceding vehicle may occur, or in some cases, splashed water droplets or the like may be mistaken for the preceding vehicle. Also, when the road surface is wet, the amount of reflected light from the road surface tends to increase compared to the dry road surface, so depending on the setting of the detection area where the reflected light is observed by irradiating light, May be detected and the road surface may be mistaken for a preceding vehicle.
[0003]
For this reason, it is necessary to detect the wetness of the road surface in the vehicle and to identify the reflected light from the road surface (particularly wet road surface) in the vehicle radar. There was no technology to answer.
[0004]
[Problems to be solved by the invention]
Therefore, there were the following adverse effects.
(B) It was not possible to sufficiently detect the wet condition of the road surface to ensure the safety of the vehicle and to properly use the optical vehicle radar.
(B) In order to prevent misleading of the preceding vehicle due to road surface reflection, the vertical spread of the detection area of the vehicle radar (that is, the viewing angle in the vertical direction) is limited to prevent detection of road surface reflected light. There was a need to do. For this reason, the possibility of the failure of losing sight of the preceding vehicle (so-called preceding vehicle lost) due to a change in the posture of the vehicle due to the unevenness of the road surface could not be sufficiently reduced. In addition, since the vertical viewing angle is narrow and there is no room, there is a problem that vertical optical axis adjustment work (work to adjust the vertical center of the detection area to an appropriate position) is necessary for each vehicle. It was.
[0005]
FIG. 5A is a diagram showing a laser radar 11 (comparative example to the present invention) having a function of estimating a rainfall state from raindrops attached to the surface of the optical head. The laser radar 11 includes a scanning device (not shown), an LD (laser diode) 12, a light projecting circuit 13, a scanning position detector (not shown), a PD (photodiode) 15, a light receiving circuit 16, and a control circuit 17. And an LD 18 for detecting raindrops.
Here, the scanning device scans the laser beam output from the LD 12 at a predetermined angle in the left-right direction (horizontal direction), usually by a reflection mirror that is driven to oscillate. The angle range is slightly wider than the detection area in the left-right direction) and is controlled by the control circuit 7 to operate at a predetermined timing and cycle.
The light projecting circuit 13 is a circuit that is controlled by the control circuit 17 and operates the LD 12 at each light emission timing created by the control circuit 17 to output laser light.
The scanning position detection unit is an element that detects the scanning direction of the scanning device and inputs the signal (scan direction signal) to the control circuit 17.
The PD 15 receives the reflected light returned from the irradiated laser light reflected by the object to be detected at a sampling period corresponding to the light emission timing, and an electric signal corresponding to the amount of light (hereinafter referred to as a received light amount signal). The received light amount signal output from the PD 15 is input to the control circuit 17 via the light receiving circuit 16. The received light amount signal is set in advance as a stored value in the control circuit 17, for example, after the noise component is removed by filtering processing (for example, averaging processing of a plurality of data) in the control circuit 17 as necessary. When the received light amount signal exceeds this threshold, it is used as detected reflected light data.
[0006]
The LD 18 for detecting raindrops emits laser light for detecting raindrops. The laser light output from the LD18 is in this case detected by a detection head of the radar 11 by an optical system such as a light projecting lens (not shown). The light is obliquely projected onto the area near the light receiving surface.
The control circuit 17 includes a microcomputer (hereinafter referred to as a microcomputer) composed of, for example, a CPU, a ROM, a RAM, and the like, and performs a distance measuring operation by the following control process during normal operation of the apparatus.
In other words, the scanning device and the light projecting circuit 13 are controlled as described above, and the propagation delay time from the light emission to the light reception of the detected reflected light (that is, the reflected light whose light amount exceeds the threshold value) is monitored. The distance to the detection object (measurement distance) is calculated, the direction of the detection target is determined from the scanning direction at that time, the intensity of the reflected light is determined based on the magnitude of the received light amount signal, and these data (distance, From the direction and the amount of light received, the detection object is discriminated and moved, and detection data including type information, position information, size information, etc. of the detection object is output.
In this case, the control circuit 17 performs a rain detection process separately from the distance measuring operation. That is, for example, the LD 18 is periodically operated to emit laser light via a drive circuit (not shown), and the received light amount signal is read from the PD 5 at a sampling period corresponding to this light emission timing, and is applied to an area near the light receiving surface. Based on the fact that the read light amount signal exceeds the threshold value set so that the reflected light of a raindrop 20 can be detected (for example, the threshold value set separately for raindrop detection), the raindrop 20 For example, when raindrops 20 are detected intermittently, a signal indicating that the raindrop is present (a state where the raindrops sequentially flow down the light receiving surface) is output to the outside.
[0007]
  According to the laser radar 11 described above, it is possible to determine the rainfall state with a certain degree of reliability, and further to estimate that the road surface is wet as a result. However, since the road surface is not directly determined to be wet, its reliability is not always sufficient. In particular, when it is not raining but the road surface is wet, it is likely to be erroneously determined as a normal state. Moreover, the raindrop detection LD 18 and its peripheral elements (such as an optical system and a drive circuit for the LD 18) are required, and there is a disadvantage that the apparatus becomes complicated and large, and the cost is high.
  Therefore, the present invention mainly aims to eliminate the adverse effects on the vehicle caused by the wet road surface,For more information,It is an object of the present invention to provide an optical vehicle distance measuring device that can distinguish reflected light from a road surface from reflected light from other vehicles.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, the inventors conducted a driving experiment on a radar-equipped vehicle. As a result, the distance measured for the reflection from the road surface is almost constant, and the detection head of the distance measuring means (radar) is It is within a specific distance range near the vehicle determined by the mounting position and angle, the light level may increase when the road surface is wet, and it may exceed the normal threshold for detecting the preceding vehicle, etc. The amount of light reflected from the wet road surface may fluctuate irregularly across the above threshold.found.
[0012]
  Each invention of the present application has been made on the basis of the above knowledge.The vehicle distance measuring device irradiates light to a detection area covering the road surface around the vehicle, receives reflected light of the irradiated light, and when the amount of received reflected light exceeds a set threshold value, A vehicle capable of performing a distance measuring operation for generating distance data as a distance information to a detected object based on a time until reception of the reflected light based on detection of the reflected light. Range finding device,
  When the distance measuring operation is performed a plurality of times, the reflected light is reflected from the road surface based on the fact that the generated distance data is in a specific distance range in the plurality of distance measuring operations. Control processing means for identifying
  According to the present invention, the reflected light from the road surface is identified only by the basic function (ranging operation) of the distance measuring means, and for example, the data of the reflected light from the road surface can be excluded.
  For this reason, even if the viewing angle in the vertical direction is widened to receive reflected light from the road surface, malfunctions that misidentify the road surface as a preceding vehicle do not occur, and it is necessary to limit this viewing angle narrowly as in the past. Disappears. And since the vertical field of view can be set widely in this way, the possibility of the preceding vehicle lost due to the change in the posture of the vehicle due to the unevenness of the road surface can be sufficiently reduced, and the optical axis adjustment work in the vertical direction becomes unnecessary or simple. Adjustment work is required.
[0013]
  The first vehicle distance measuring device of the present application isIn the plurality of distance measuring operations, the control processing means has the determined distance data in a specific distance range, and the reflected light in the specific distance range is detected more than a specified number of times, and is detected more than a specified number of times. If not (that is, if the amount of reflected light in the distance range fluctuates across the threshold), the reflected light is identified as reflected light from the road surface.
  For this reasonThe reflected light from the road surface can be identified more reliably. This is because the reflected light from the road surface varies in an unstable manner unlike the reflected light from the reflectors of other vehicles.
[0014]
  The first vehicle distance measuring device of the present application isIn the plurality of distance measuring operations, the control processing means sets the light emission power of the irradiation light and / or the light receiving sensitivity of the reflected light to a high setting that makes it easy to detect the reflected light from the road surface and difficult to detect the reflected light from the road surface. To a low setting.
  For this reasonThe light reflected from the road surface can be identified with higher reliability. This is because when the light emission power changes, the reflected light from the road surface fluctuates more greatly, and the phenomenon of being detected or not detected becomes more reliable and clear.
[0015]
  Further, the second vehicle distance measuring device of the present application irradiates light to a detection area extending over the road surface around the vehicle, receives reflected light of the irradiated light, and sets a threshold value of the amount of the received reflected light Ranging to generate distance data to the reflection point of the reflected light as distance information to the detected object based on the time until the reflected light is received, assuming that the reflected light is detected A vehicle ranging device capable of performing an action,
  High setting that makes it easy to detect the reflected light from the road surface within the range where the reflected light from other vehicles can be detected.WhenLow setting where the reflected light from the road surface is difficult to detectWhenThe distance measurement operation is executed a plurality of times, and when the distance data to the closest object to be detected changes discontinuously in the plurality of distance measurement operations, the low setting state is set. Control processing means for identifying the reflected light detected as the reflection from the closest object to be detected as the reflection from the road surface is provided.
  According to the present invention, the presence of the reflected light from the road surface and its distance can be determined by the relative change of the distance data in the state where the reflected light from the road surface is detected unstable (change in the observation distance of the closest object). Deciding. That is, data in a specific distance range set in advance as in the above-described invention is not estimated as data of reflected light from the road surface. For this reason, even if the mounting position and angle of the detection head of the distance measuring device change due to vibrations when the vehicle travels and the actual distance range of the reflected light from the road surface changes, the reflected light from the road surface Identification can always be realized with high reliability, and as a result, it is possible to more reliably avoid problems such as misidentifying the road surface as a preceding vehicle.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
  1A and 1B are diagrams for explaining the apparatus configuration and the like of the first embodiment. FIG. 1A is a block diagram showing the configuration of the laser radar 21, and FIG. FIG. FIG. 2 is a flowchart showing a characteristic processing operation of the radar 21 of this embodiment. Here, the same elements as those shown in FIG. 5 (comparative example) described above are denoted by the same reference numerals, and redundant description is omitted.
  In addition, the utilization form in the vehicle of the information obtained by the radar 21 of this example is not specifically limited, What kind of thing may be sufficient. In any case, it can be effectively used to realize advanced functions such as the preceding vehicle monitoring function (including inter-vehicle distance monitoring) and preceding vehicle following control. In particular, the radar 21 of this embodiment isThe vehicle road surface condition detection device itselfIn addition to the position information of the preceding vehicle (detected object), etc., information on whether or not the road surface is wet can be obtained, so the braking force is limited according to the road surface state. It is possible to realize a control function that enhances safety, such as limiting the vehicle speed according to the road surface condition, increasing the target inter-vehicle distance, or canceling or prohibiting the preceding vehicle following control or auto cruising driving according to the road surface condition. It becomes.
[0017]
  Radar 21 (Ranging device of the present inventionIs equivalent to the radar 11 shown in FIG. 5, the scanning unit, the LD 12, the light projecting circuit 13, the scanning position detecting unit, the PD 15, the light receiving circuit 16, and the control circuit 27 (Control processing means of the present inventionEquivalent).
  The control circuit 27 includes a microcomputer, and controls the distance measuring operation and determines whether or not the road surface is wet when the apparatus is in operation (details will be described later).
  Note that in a vehicular radar, a detection area is usually set only in front of the vehicle in order to obtain information about an object to be detected in front of the vehicle, and a method of scanning only in the left-right direction (horizontal direction) is generally used. Is. The present invention is not limited to this, but the present embodiment also assumes such a configuration.
  However, in this case, as shown in FIG. 1B, for example, the vertical spread of the detection area (viewing angle in the vertical direction) is increased by expanding the vertical spread of the laser beam 24 to be irradiated. It is larger than before, and is configured to actively receive reflected light from the road surface.
[0018]
Next, the operation of the radar 21 will be described. First, the basic operation (ranging operation) as a radar will be described.
The LD 12 is controlled by the light projecting circuit 13 to output laser light at each light emission timing created by the control circuit 27. Then, the laser beam 24 from the LD 12 is scanned in the left-right direction by a scanning device, and is irradiated as illustrated in FIG. Note that the detection area in the left-right direction is usually set to be slightly smaller than the scanning range (scan area) where laser light is actually irradiated.
When the irradiated laser light is reflected back to the detection target (for example, a reflector on the rear surface of the preceding vehicle 2), the reflected light is received by the PD 15 and the received light amount signal is passed through the light receiving circuit 16. Is input to the control circuit 27 and detected. The control circuit 27 first generates measurement data (distance, direction, received light amount) from the received light amount signal and the scan direction signal input from the scanning position detector.
Note that this measurement data (distance, direction, received light amount) includes the distance data of the present invention, and is generated each time detection of light emission and reflected light is performed in the detection area. A plurality can be obtained according to the resolution in the horizontal direction.
[0019]
The control circuit 27 performs the following processing based on the above data (distance, direction, received light amount) and speed data V of the host vehicle input from a vehicle speed sensor (not shown) in a predetermined cycle (in this case, laser (Cycle in which light is scanned).
That is, first, the distance to the object and the direction data (polar coordinate data) are converted into X and Y coordinates (Cartesian coordinate data) and stored in a memory (not shown) for each region together with the received light amount data. Here, each area is an area set in advance by dividing the detection area in the left-right direction into, for example, equal divisions.
[0020]
Next, based on the distance data in the memory converted into the Cartesian coordinate system and registered for each region, the data is grouped to extract the target object, and the laser emission unit of the grouped target object The distance in the X direction (for example, the left-right direction) and the Y direction (for example, the front-rear direction) and the width dimension are calculated.
Here, the grouping is a process of collecting adjacent data that are close to each other in the individual data of each region and making it one object. Specifically, for example, windows (areas on the Cartesian coordinate system) having a certain width are provided for each data in the front-rear direction and the left-right direction, and the other data included in this window are grouped together. Note that the data grouped in this way (hereinafter referred to as group data) is handled collectively as one object in the subsequent processing.
[0021]
Next, the object detected during the previous scan is associated with the object detected during the current scan, and the relative speed of the detected object is further calculated.
That is, a fixed window is set around the position where the group data is estimated to appear during the current scan from the previous group data position and its relative speed. Then, it is determined whether or not the current group data is in this window, and if it is within this range, the previous group data and the current group data are handled as being for the same object. In addition, relative speeds Vx (left-right direction) and Vy (front-back direction) are calculated from the movement distances.
Next, stop object discrimination of the object is performed based on the relative speed of the object.
That is, by comparing the relative speed Vy of the object with the speed V of the host vehicle (speed detected by the vehicle speed sensor), it is determined whether the object is stopped or moving. That is, for example, when the vehicle speed V and the relative speed Vy are approximately equal in the reverse direction, it is determined that the vehicle is a stopped object.
[0022]
Next, based on the determination result, for example, a preceding vehicle that is a target of a front obstacle monitoring system or a follow-up traveling control system is specified. Information (position data, relative speed data, etc.) relating to the identified preceding vehicle and the like is sequentially transmitted to the control means of the front obstacle monitoring system and the follow-up traveling control system, and used for operation control of these systems. .
[0023]
Next, processing relating to the road surface state executed by the control circuit 27 will be described. For example, when the radar 21 is in operation, the control circuit 27 repeatedly executes the processing shown in FIG.
First, the same process as the series of distance measuring operations described above (at least the process of generating the above-described measurement data for one scan) is executed a predetermined number of times a plurality of times (step S1). Note that the processing in step S1 may be performed as a normal distance measuring operation as the radar described above (performed for follow-up traveling control or the like), or separately from the road surface. It may be performed only to determine the state. In addition, the prescribed number of times is set by an experiment or the like so that the reliability of road surface condition determination can be obtained sufficiently. In addition, when performing separately from the normal distance measuring operation, the threshold value of the light amount for detecting reflected light in the distance measuring operation in step S1 is set to a value different from that of the normal distance measuring operation as necessary. May be. However, the threshold value in this case needs to be set according to the light emission power or the like so as to be between the maximum value and the minimum value of the amount of reflected light from the wet road surface that fluctuates in an unstable manner. For example, as shown in FIG. 3A, the threshold value is set to such a value that the amount of reflected light from the wet road surface (in this case, the value at the top of the waveform) fluctuates between detection and non-detection. Is preferably set.
[0024]
Next, in step S2, the reflected light estimated to be reflected light from the road surface based on the distance data among the measurement data generated in the distance measuring operation in step S1 is detected more than the specified number of times, and the specified number of times. It is determined whether or not it has been detected. In addition, what is necessary is just to determine the prescription | regulation frequency here suitably in the range of at least 1 time or more. If this specified number of times is set large, the reliability of road surface condition determination will increase, but if it is too large, the processing speed of the determination will decrease, so it is set to the minimum value that can provide the necessary and sufficient reliability. Is preferred. Further, a different specified number of times may be set such that the detected specified number of times is two or more and the specified number of undetected times is one or more. Here, “reflected light estimated to be reflected light from the road surface based on distance data” is reflected light from a specific distance range that may cause road surface reflection. That is, when a graph is drawn with the horizontal axis as the distance data and the vertical axis as the amount of received light, the reflected light from the road surface is always within a specific distance range (for example, about 12 to 13 m) as shown in FIG. It has been demonstrated by the inventors' research that this distance range is uniquely determined (also theoretically required) by the mounting position and angle of the radar detection head (the portion that emits and receives light). Therefore, here, focusing on the reflected light in such a distance range, the detection state of the reflected light is determined a plurality of times. As for the scan angle, the detection state of reflected light in such a specific distance range may be determined for the entire angle range, or only a specific scan angle (for example, the front direction of the vehicle) may be determined. May be.
[0025]
And, since the reflected light in the distance range is detected more than a specified number of times (for example, twice) and not more than a specified number of times (for example, once), the result of the determination in step S2 becomes affirmative (ie, If the amount of reflected light in the distance range fluctuates across the threshold and is not detected), the process proceeds to step S3, where it is determined that the road surface is wet, and if necessary, The signal is output to the outside.
On the other hand, the reflected light in the distance range is detected less than the specified number of times (for example, 2 times), or detected more than the specified number of times (for example, 2 times), but the detected number of times reaches the specified number of times (for example, 1 time). If the result of the determination in step S2 is negative (ie, the amount of reflected light in the distance range is stable below the threshold or exceeds the threshold) If the road surface is stable, the process proceeds to step S5, where it is determined that the road surface is not wet (or whether it is unknown whether the road surface is wet), and a signal to that effect is output to the outside as necessary. The reason why the road surface is not determined to be wet when the amount of reflected light in the distance range is stable in the state of exceeding the threshold is as follows. In other words, the reflected light from the road surface fluctuates in an unstable manner as described above. Therefore, if the threshold value is set appropriately, the reflected light having such a stable detection state is not reflected by the reflected light from the road surface. This is because the vehicle is a preceding vehicle or a roadside reflector (appropriate monitoring target).
[0026]
  After step S3, in step S4, the reflected light data in the distance range determined to be unstable in step S2 is excluded from the monitoring target as road surface data (for example, The above-described calculation of relative speed and determination processing such as whether or not the vehicle is a stationary object are not performed, and are not adopted as data for follow-up traveling control or the like).
  Further, after step S4 or S5, the processing of one sequence is finished.
In the multiple ranging operations executed in step S1 (FIG. 2), the light emission power or / and the light receiving sensitivity of the radar is set to a high setting that makes it easy to detect the reflected light from the wet road surface and from the wet road surface. The reflected light is changed to a low setting that is difficult to detect. Thereby, the detection state of the reflected light from the road surface changes more reliably, and the determination in step S2 (determination of whether or not the road surface is wet) is more reliable. When the light emission power is low to some extent, as shown in FIG. 3B, the preceding vehicle or the like is detected exceeding the threshold value, but the reflected light from the road surface (including a wet road surface) is hardly received ( This is because it is not detected at all).
[0027]
According to the laser radar 21 described above, the reflected light from the road surface is identified only by the basic configuration as a radar, and it is possible to directly detect that the road surface is wet from the light quantity and distance data of the reflected light.
For this reason, it is possible to sufficiently detect the wet state of the road surface with high reliability and to ensure the safety of the vehicle and appropriately utilize the optical vehicle radar. Specifically, the vehicle driver is warned by sound or display that the road surface is wet and dangerous, or control is performed so that excessively strong braking does not work when the road surface is wet, Limiting the maximum speed when the road surface is wet, increasing the target inter-vehicle distance in automatic tracking when the road surface is wet, or prohibiting automatic tracking control by radar when the road surface is wet Alternatively, it is possible to accurately cope with the road surface condition such as forced stop.
Even if the reflected light from the road surface is received by widening the viewing angle in the vertical direction, malfunctions that misidentify the road surface as a preceding vehicle will not occur, so it is necessary to limit this viewing angle narrowly as before. Disappears. And since the vertical field of view can be set widely in this way, the possibility of the preceding vehicle lost due to the change in the posture of the vehicle due to the unevenness of the road surface can be sufficiently reduced, and the optical axis adjustment work in the vertical direction becomes unnecessary or simple. Adjustment work is required.
In addition, unlike the comparative example shown in FIG. 5A, there is no need to add a special element other than the basic configuration, so that the apparatus can be reduced in size and cost.
[0028]
(Second embodiment)
Next, FIG. 4 is a flowchart showing characteristic processing operations of the second embodiment. In addition, this example illustrates another form of the configuration for identifying the reflected light from the road surface, and the other configuration (including the device configuration) may be the same as the first embodiment.
In this case, the control circuit 27 does not execute at least the process of step S4 shown in FIG. 2, but repeatedly executes the process shown in FIG. First, the same process as the series of distance measuring operations described above (at least the process of generating the above-described measurement data for one scan) is executed a predetermined number of times a plurality of times (step S11). Note that the processing in step S11 may also be performed as a normal ranging operation as the above-described radar, or separately performed only for identifying reflected light from the road surface. But you can. However, in this case, the light emission power of the irradiation light and / or the light reception sensitivity of the reflected light is set within a range where the reflected light from other vehicles can be detected, and the reflected light from the road surface is easily detected and reflected from the road surface. The distance measurement operation is executed a plurality of times by changing to a low setting where light is difficult to detect (for example, by alternately changing).
[0029]
Next, in step S12, in order to identify the reflected light from the road surface, as a result of the distance measuring operation in step S11, the distance data of the reflected light from the closest reflection point in front of the vehicle changed discontinuously. It is determined whether or not. Specifically, for example, it is determined whether or not the amount of change in the distance data exceeds a value that cannot be normal (a value that makes the relative speed abnormally large). This is because if the reflected light from an appropriate target object (other than the road surface) such as the preceding vehicle is always observed as the shortest distance, the change in the distance data will affect the relative speed of the target object. However, if the reflected light on the road surface between the vehicle and the preceding vehicle is detected in an unstable manner, it is observed as the shortest distance to the vehicle. Whether the object is a road surface or a preceding vehicle changes in an unstable manner for each measurement, and accordingly, the distance data to the closest object also fluctuates in an unstable manner. Particularly in step S11 in this case, the reflected light from the road surface is reliably detected because the light emission power of the irradiation light and / or the light receiving sensitivity of the reflected light are changed between the high setting and the low setting as described above. Or will not be detected. Therefore, in step S12, the reflected light data on the road surface is identified using such a phenomenon.
[0030]
If the determination in step S12 is affirmative, it can be determined that there is reflected light from the road surface, and therefore the process proceeds to step S13 to exclude the data of reflected light from the road surface. Specifically, the reflected light detected as the reflection from the closest object to be detected in the high setting state described above is identified as the reflection from the road surface, and the reflected light data is excluded from the monitoring target. To do. Note that after step S12 or S13, the processing of one sequence is completed.
[0031]
According to the second embodiment described above, the reflected light from the road surface is changed by the relative change in the distance data in the state where the reflected light from the road surface is detected in an unstable manner (change in the observation distance of the closest object). Judging existence and its distance. That is, data in a specific distance range set in advance as in the first embodiment described above is not estimated as data of reflected light from the road surface. For this reason, even if the mounting position and angle of the radar detection head change due to vibrations during traveling of the vehicle and the actual distance range of the reflected light from the road surface changes, the reflected light from the road surface can be identified. It can always be realized with high reliability, and as a result, it is possible to more reliably avoid problems such as misidentifying the road surface as a preceding vehicle.
[0034]
In addition, this invention is not restricted to the said example of an aspect, There can exist various aspects and deformation | transformation.
For example,When the multiple distance measuring operations executed in step S1 (FIG. 2) of the first embodiment are performed only for the determination of the road surface state, the scanning operation is not necessarily required, for example, directly in front of the vehicle. Ranging operation may be performed only in the direction.
Also,The light irradiation direction (the direction of the detection area) is not limited to the front of the vehicle. In some cases, the vehicle may be irradiated to the rear or side of the vehicle.
  Also,Ranging device of the present inventionIs not limited to a laser radar using laser light, but may be any radar as long as it uses reflection of light (or a wave equivalent to light in the behavior with respect to a wet road surface or water droplets).
[0035]
【The invention's effect】
  According to the vehicle distance measuring device of the present application, the reflected light from the road surface is identified only by the basic function (ranging operation) of the distance measuring means, and for example, the data of the reflected light from the road surface can be excluded. For this reason, even if the viewing angle in the vertical direction is widened to receive reflected light from the road surface, malfunctions that misidentify the road surface as a preceding vehicle do not occur, and it is necessary to limit this viewing angle narrowly as in the past. Disappears. And since the vertical field of view can be set widely in this way, the possibility of the preceding vehicle lost due to the change in the posture of the vehicle due to the unevenness of the road surface can be sufficiently reduced, and the optical axis adjustment work in the vertical direction becomes unnecessary or simple. Adjustment work is required.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a radar device and the like.
FIG. 2 is a flowchart showing road surface condition determination processing and the like.
FIG. 3 is an example of data explaining the principle of road surface reflected light identification and road surface state determination.
FIG. 4 is a flowchart showing road surface reflected light identification processing (another example).
FIG. 5 is a diagram for explaining a device configuration of a conventional radar.
[Explanation of symbols]
21 Laser radar (ranging means, distance measuring device, road surface condition detecting device)
24 Laser light
27 Control circuit (road surface condition judging means, control processing means)

Claims (2)

It is assumed that the reflected light is detected when the detection area covering the road surface around the vehicle is irradiated with light, the reflected light of the irradiated light is received, and the amount of the received reflected light exceeds the set threshold value. A vehicle distance measuring device capable of performing a distance measuring operation for generating distance data to a reflection point of the reflected light as distance information to the detected object based on a time until the reflected light is received. ,
When the distance measuring operation is performed a plurality of times, the reflected light is reflected from the road surface based on the fact that the generated distance data is in a specific distance range in the plurality of distance measuring operations. Control processing means for identifying
The control processing means includes
When the determined distance data is in a specific distance range and the reflected light in this specific distance range is detected more than the specified number of times and not detected more than the specified number of times in the plurality of distance measuring operations, this reflection is performed. While identifying the light as reflected from the road surface,
In the multiple distance measurement operations, the emission power of the irradiated light and / or the sensitivity of the reflected light is changed to a high setting where the reflected light from the road surface is easy to detect and a low setting where the reflected light from the road surface is difficult to detect. A vehicle ranging device characterized in that the vehicle ranging device is provided. It is assumed that the reflected light is detected when the detection area covering the road surface around the vehicle is irradiated with light, the reflected light of the irradiated light is received, and the amount of the received reflected light exceeds the set threshold value. A vehicle distance measuring device capable of performing a distance measuring operation for generating distance data to a reflection point of the reflected light as distance information to the detected object based on a time until the reflected light is received. ,
The light emission power of the irradiation light and / or the light receiving sensitivity of the reflected light are within a range where the reflected light from other vehicles can be detected, and the setting is high so that the reflected light from the road surface can be easily detected, and the reflected light from the road surface is difficult to detect. by changing the settings and the distance measuring operation is performed a plurality of times, the distance measuring operation of the plurality of times, when the closest distance of the distance data up to the object is changed discontinuously, the height setting A vehicle distance measuring device comprising control processing means for identifying reflected light detected as reflection from an object to be detected at a shortest distance in the state as reflection from a road surface.

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