JP2017111529A - Obstacle determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an obstacle determination device with which it is possible to determine the presence of an obstacle by taking into account the effects of rain and snow.SOLUTION: An obstacle determination device 1 comprises: a distance measurement device 2 for emitting an electromagnetic wave for distance measurement to a prescribed range, and measuring the distance to a reflection point by a reflected wave on each prescribed cycle; and an obstacle determination unit 31 for determining the presence of an obstacle on the basis of the number of reflection points within a prescribed area provided within the prescribed range that were detected during the prescribed cycle. The obstacle determination unit 31 has an estimation unit 31c for estimating a noise point that is a reflection point due to snow and/or rain among the reflection points within the prescribed area, and a history storage unit 41d for storing a history on the number of reflection points per prescribed cycle within the prescribed area that were estimated to be noise points, the obstacle determination unit determining the presence of an obstacle on the basis of the number of reflection points on the prescribed cycle within the prescribed area and the history of a determination object.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an obstacle determination device, and more particularly to an obstacle determination device that determines the presence or absence of an obstacle based on a measurement result by a distance measuring device.

  A distance measuring device configured as a distance measuring sensor can measure a distance to an object existing within a measurement range, and can acquire a one-dimensional or two-dimensional distance data map. For example, the distance measuring device is used as a safety device that determines its own operation using the measured distance information, and an autonomous traveling device acting autonomously detects and avoids an obstacle.

  Among the distance measuring devices, the optical type has a light emitting part and a light receiving part inside the casing, and transmits and receives light through a transparent optical window, so that the distance to the object, that is, the distance to the reflection point Is calculated. The distance measuring device outputs distance information to the reflection point at coordinates within the measurement range.

  Patent Document 1 relates to an obstacle determination technique, and is a mobile robot that scans a road surface ahead by a laser sensor at a predetermined cycle while traveling at a predetermined speed, and a plurality of data obtained by a plurality of scans. Among them, there is disclosed one that determines whether there is an obstacle when data of a predetermined number of times or more is obtained at the same place. This mobile robot can detect an obstacle with high accuracy even when there is a puddle on the road surface.

JP 2008-9929 A

FIG. 6 is a diagram for explaining the problems of the prior art.
The distance measuring device of the moving body 100 in FIG. 6 emits laser light so as to scan radially, and calculates a distance to a reflection point based on reflected light with respect to the emitted light. The moving body 100 is equipped with an obstacle determination device that determines the presence or absence of an obstacle based on the measurement result of the distance measuring device, and travels based on the determination result of the obstacle determination device. A deceleration area A101 and a stop area A102 are provided for the moving body 100.

  The obstacle determination device of the moving body 100 determines that there is an obstacle when a predetermined number or more of reflection points P101 are detected in the deceleration area A101 or when a predetermined number or more of reflection points are detected in the stop area A102. . And according to this determination result, the mobile body 100 decelerates or stops.

However, the snow particles also reflect the laser beam, and the distance measuring device cannot determine whether the reflection point is due to the snow particles. Therefore, if the number of reflection points is simply a predetermined number or more and it is determined that there is an obstacle and the moving body 100 is decelerated / stopped, if there are many reflection points due to snow particles, there is no obstacle even though there are no obstacles. It will make a false decision that there is something.
The same applies to raindrops.
Patent Document 1 does not disclose or suggest this point.

  The present invention has been made in view of the above circumstances, and provides an obstacle determination device capable of determining the presence or absence of an obstacle in consideration of the influence of precipitation such as rain or snow. Objective.

  In order to solve the above-described problem, the first technical means of the present invention is a distance measuring method that emits a distance measuring electromagnetic wave to a predetermined range and measures a distance to a reflection point by a reflected wave at predetermined intervals An obstacle comprising: an apparatus; and an obstacle determination unit that determines the presence or absence of an obstacle based on the number of reflection points in a predetermined area provided within the predetermined range, detected during the predetermined period An object determination device, wherein the obstacle determination unit estimates a noise point that is a reflection point due to precipitation among the reflection points in the predetermined region, and the predetermined region in the predetermined region A history storage unit that stores a history of the number of reflection points estimated to be noise points, and based on the number of reflection points in the predetermined region in the predetermined period to be determined, and the history Determining the presence or absence of the obstacle. .

  According to a second technical means of the present invention, in the first technical means, the obstacle determination unit includes the number of the reflection points in the predetermined area in the predetermined period of the determination target and the predetermined period. It is characterized in that the presence or absence of the obstacle is determined based on the number of reflection points estimated to be noise points and the most frequent frequency in a predetermined latest period.

  According to a third technical means of the present invention, in the first technical means, the obstacle determination unit includes the number of the reflection points in the predetermined area in the predetermined period of the determination target and the predetermined period. The presence or absence of the obstacle is determined based on an average value of the number of reflection points estimated to be noise points in a predetermined most recent period.

  According to a fourth technical means of the present invention, in the second or third technical means, the obstacle determination unit outputs the determination result when the determination result that there is an obstacle is continued twice. It is what.

  According to a fifth technical means of the present invention, in any one of the first to fourth technical means, the predetermined area is provided outside the obstacle determination device.

  According to a sixth technical means of the present invention, in any one of the first to fifth technical means, the estimation unit determines only the noise existing at a specific position among the reflection points in the predetermined area. It is characterized in that it is a determination target of whether or not it is a point.

  According to the obstacle determination device of the present invention, the presence or absence of an obstacle can be determined in consideration of the influence of precipitation.

It is a block diagram showing an example of composition of an obstacle judging device concerning a 1st embodiment of the present invention. It is a figure which shows the example of an external appearance structure of the obstruction determination apparatus of FIG. It is a figure explaining an example of the method of estimating the thing by noise among reflection points. It is a figure explaining an example of the method of determining the presence or absence of an obstruction. It is a simplified top view of the obstacle determination device according to another embodiment of the present invention. It is a figure for demonstrating the subject of a prior art.

  Hereinafter, preferred embodiments of the obstacle determination device of the present invention will be described with reference to the drawings. In the following inventions, the same reference numerals in different drawings are the same, and the description thereof may be omitted.

(First embodiment)
FIG. 1 is a block diagram illustrating a configuration example of an obstacle determination apparatus according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating an external configuration example of the obstacle determination apparatus in FIG. 1. The obstacle determination device of the present example is configured as an autonomous traveling device that autonomously travels such as detecting an obstacle and decelerating or stopping according to the distance from the obstacle.
The obstacle determination device 1 includes a main body 3 and an optical distance measuring device 2 attached to the main body 3. The distance measuring device 2 measures the distance to the measurement object by an optical method.

  The optical distance measuring device 2 irradiates the light for distance measurement (hereinafter referred to as measurement light) output from the laser light source with an eccentricity, and detects the reflected light from the measurement object with the light receiving element through the optical window. Then, the distance to the measurement object, that is, the distance to the reflection point is measured. An AM (Amplitude Modify) method and a TOF (Time of Flight) method have been put to practical use as measurement light modulation methods. In the AM method, the measurement light that has been AM-modulated with a sine wave and its reflected light are photoelectrically converted, a phase difference between these signals is calculated, and a distance is calculated from the phase difference. The TOF method is a method in which a measurement light modulated in a pulse shape and its reflected light are photoelectrically converted, and a distance is calculated from a delay time between these signals. Any of the above-described methods can be applied to the distance measuring apparatus of the present embodiment.

The distance measuring device 2 emits measurement light and measures a distance to a reflection point (also referred to as a measurement point) with reflected light for a predetermined range every predetermined period. The distance measuring device 2 scans a predetermined range (hereinafter referred to as a measurement range) one-dimensionally or two-dimensionally with measurement light and receives reflected light at predetermined intervals, for example, to reflect points within the measurement range. The distance to is calculated. In the case of performing one-dimensional scanning, the measurement range of the distance measuring device 2 has a sector shape centered on an optical mechanism unit 23 described later of the distance measuring device 2. In addition, the measurement range in the case of two-dimensional scanning has a vertical and horizontal sector shape centered on the optical mechanism 23 of the distance measuring device 2.
Typical examples of the distance measuring apparatus 2 include 2D-LIDAR (Light Detection and Ranging or Laser Imaging Detection and Ranging), 3D-LIDAR, and laser range finder. The laser range finder is a distance measuring sensor that employs the TOF method. By providing one or two scanning axes, two-dimensional plane measurement and three-dimensional measurement are possible. LIDAR can also be said to be a kind of laser range finder.

In addition, the distance measuring device 2 emits light such as infrared light from the light emitting unit without scanning light, and the light receiving element is irradiated with a two-dimensional light receiving sensor (for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). Image Sensor)) can be used to measure the distance to the reflection point within a certain measurement range based on the light reception result of the two-dimensional light receiving sensor.
In the following description, the distance measuring device 2 will be described as an example in which a predetermined measurement range is one-dimensionally scanned with measurement light.

  The distance measuring device 2 in FIG. 1 drives and scans a light emitting unit 22 that outputs measurement light, a light receiving unit 24 that receives reflected light of the measurement light emitted from the light emitting unit 22, and an optical path of the emitted measurement light. An optical mechanism unit 23 provided with an optical path adjusting means such as a mirror for guiding the reflected light to the light receiving element, and a drive control unit 21 for performing light emission driving of the light emitting unit 22 and driving control of the optical path adjusting unit of the optical mechanism unit 23; And a distance calculation unit 25 that calculates the distance to the reflection point based on the output signal photoelectrically converted by the light receiving unit 24 and the optical path drive information from the drive control unit 21. The distance measuring device 2 outputs the information on the distance to the reflection point calculated by the distance calculation unit 25 as the position information of the reflection point together with the emission angle of the measurement light when the reflection point is obtained.

The position information of the reflection point output from the distance calculation unit 25, that is, the distance measurement result is input to the obstacle determination unit 31 of the main body unit 3.
The obstacle determination unit 31 determines the presence or absence of an obstacle in a predetermined area provided within the measurement range of the distance measuring device 2 based on the measurement result by the distance measuring device 2. When it is determined that there is an object (an object to be recognized as an obstacle as an obstacle) in the predetermined area in front of the obstacle determination device 1, the obstacle determination unit 31 determines that there is an obstacle. Is a feature of the present embodiment and will be described later. The predetermined area is a so-called measurement area (obstacle detection area) and can be said to be an area indicating a coordinate space of a reflection point (measurement point).
The obstacle determination unit 31 outputs the determination result to the main body operation control unit 32 of the main body unit 3.

The main body 3 includes a drive unit 34 that causes the obstacle determination apparatus 1 to travel. The drive unit 34 includes, for example, a plurality of wheels and a motor for rotating the wheels. The drive control unit 33 controls the drive of the drive unit 34 according to the control of the main body operation control unit 32.
The main body operation control unit 32 controls the operation of the main body unit 3.

  The drive control unit 33 controlled by the main body operation control unit 32 drives the drive unit 34 according to the control of the main body operation control unit 32. For example, the drive control unit 33 rotates the four wheels to cause the obstacle determination apparatus 1 to travel, or changes the rotation direction and rotation speed of the four wheels to change the direction of the main body unit 3. Take control.

The obstacle determination unit 31 determines an obstacle to be avoided by the obstacle determination device 1, and outputs position information (distance, angle) of the obstacle to the main body operation control unit 32 as a determination result.
The main body operation control unit 32 controls the travel of the obstacle determination device 1 based on the determination result of the obstacle determination unit 31, and is based on the position information of the obstacle input from the obstacle determination unit 31. The drive control unit 33 is controlled to perform an operation for avoiding the obstacle. Here, for example, control is performed such that the traveling direction of the traveling obstacle determination device 1 is changed, or the vehicle is decelerated or stopped before the obstacle.

The obstacle determination device 1 as described above is configured by mounting the distance measuring device 2 on the upper portion of the main body 3 as illustrated in FIG. Units constituting the obstacle determination unit 31, the main body operation control unit 32, and the like are mounted inside the main body unit 3.
Further, in the example shown in the figure, four wheels 4 are attached as the drive unit of the main body unit 3 to enable automatic traveling. Each wheel 4 can be rotated forward and backward, and at least one of the rotation direction, the rotation speed, and the direction of each wheel is controlled, whereby the obstacle determination device 1 can travel.

  Next, the main features of the present embodiment will be described with reference to FIG. 1 and FIG. 3 and FIG. FIG. 3 is a diagram illustrating an example of a measurement range in the distance measuring device 2 of the obstacle determination device 1 and a predetermined area where the presence / absence of an obstacle is determined, and an example of reflection points in the measurement range. 4 (A), 4 (B), and 4 (C) are estimated as the number of reflection points in a predetermined region for each predetermined period, and noise points due to precipitation such as snow and rain among the reflection points. It is a figure which shows the example of the number of the reflection points excluding the number of objects and the influence of precipitation.

The distance measuring device 2 of the obstacle determination device 1 periodically scans the measurement range R in FIG. 3 with laser light, and calculates / measures the distance to the reflection point with the reflected light.
The obstacle determination unit 31 that acquires distance information to the reflection point from the distance measuring device 2 includes a reflection point position storage unit 31a, a reflection point count unit 31b, an estimation unit 31c, and a history storage unit 31d.

The reflection point position storage unit 31a stores the position information of the reflection points obtained from the distance measuring device 2 so as to be distinguishable for each scanning cycle (every frame) of the distance measuring device 2.
The reflection point count unit 31b counts the number of reflection points detected in the determination target frame and within the deceleration area A1 provided in the measurement range R. This counting is performed with reference to the stored contents of the reflection point position storage unit 31a.

  The estimation unit 31c refers to the reflection point position storage unit 31a, and estimates noise points that are reflection points due to precipitation such as snow, rain, hail, and hail among the reflection points in the deceleration area A1. If the reflection point is due to snow or rain, another reflection point is not detected in the same frame, or even if it is detected, other reflection points are only located at a position away from a predetermined distance (for example, 1 m) like the reflection point P11 in FIG. It is presumed that the reflection point P12 often does not exist. Therefore, the estimation unit 31c estimates a reflection point in the deceleration area A1 that has no other reflection point within a predetermined distance (for example, within 1 m) in the same frame as a noise point due to snow or the like.

  The history storage unit 31d stores the number of reflection points in the deceleration area A1 estimated as noise points by the estimation unit 31c for each frame. That is, the history storage unit 31d stores a history of the number of reflection points estimated to be noise points in the deceleration area A1 for each frame (hereinafter referred to as noise points).

  The obstacle determination unit 31 stores in the history storage unit 31d the number of reflection points in the deceleration area A1 in the frame subject to determination of the presence or absence of an obstacle (hereinafter referred to as determination target frame) counted by the reflection point number counting unit 31b. The presence / absence of an obstacle is determined based on the history of noise points in the deceleration area A1 for each frame. For example, the obstacle determination unit 31 subtracts the number of noise points in the deceleration area A1 for each frame that has the highest frequency (mode) from the number of reflection points in the deceleration area A in the determination target frame. If the subtracted value is larger than the threshold value, it is determined that there is an obstacle. The mode value is preferably a number having the highest frequency out of “0”, and the mode value in a predetermined latest period of the determination target frame, for example, the mode value in the immediately preceding tens of frames is preferable. .

  A more specific example will be described with reference to FIGS. 4 (A) and 4 (B). In this example, it is assumed that the mode value is the value with the highest frequency out of “0”, and the mode value in the last 20 frames is used. Further, it is assumed that the number of reflection points and the number of noise points in the deceleration area A1 in each frame change as shown in FIGS. 4A and 4B, respectively. Further, it is assumed that the threshold is 3.

  When the determination target frame is the 85th frame, the obstacle determination unit 31 has “4” as the number of reflection points in the deceleration area A1 of the 85th frame as shown in FIG. "Greater than." However, the mode value of the noise score in the deceleration area A1 for each frame in the 10 frames immediately before the 85th frame, that is, the 65th to 84th frames is “1”, and from the number “4” of the reflection points in the 83rd frame. Since the value obtained by subtracting the mode value “1” is “3” as shown in FIG. 4C and is equal to or less than the threshold value “3”, the obstacle determination unit 31 sets the “obstacle” for the 85th frame. It is not determined as “present”, but is determined as “no obstacle”.

  On the other hand, when the determination target frame is the 89th frame, as shown in FIG. 4A, the number of reflection points in the deceleration area A1 of the frame is “7”. Further, the mode value of the number of noise points in the deceleration area A1 for each frame in 20 frames immediately before the 89th frame, that is, the 69th to 88th frames is “1”, and the number of reflection points in the 89th frame is “7”. The value obtained by subtracting the mode value “1” is “6” as shown in FIG. 4C and is larger than the threshold value “3”. Therefore, the obstacle determination unit 31 determines that “there is an obstacle” for the 89th frame. Is determined.

  In the above example, the obstacle determination unit 31 subtracts the mode value of the number of noise points in the deceleration area A1 for each frame from the number of reflection points in the deceleration area A in the determination target frame, and subtracts the value and the threshold value. However, the mode value may be added to the threshold value, and the added value may be compared with the number of reflection points.

(Second Embodiment)
In the first embodiment, when determining the presence or absence of an obstacle, the obstacle determination unit 31 extracts and uses the mode value of the noise score in the deceleration area A1 for each frame in a predetermined latest period. On the other hand, in the second embodiment, when the obstacle determination unit 31 determines the presence or absence of an obstacle, a predetermined nearest period of the noise score in the deceleration area A1 for each frame (for example, 3 to 10 frames immediately before). The average value is calculated and used instead of the mode value of the first embodiment. When using the average value for the calculation, the part after the decimal point may be rounded down or rounded off. Further, as an average value, an average value of frames excluding a frame having the noise score of “0” may be used.

(Third embodiment)
In the above embodiment, the obstacle determination unit 31 outputs the determination result of “There is an obstacle” when it is determined that “there is an obstacle” for the determination target frame. On the other hand, in the third embodiment, when the obstacle determination unit 31 determines that “there is an obstacle” for the determination target frame, at that stage, the obstacle determination unit 31 does not output the determination result of “there is an obstacle”. When it is determined that “there is an obstacle” in the frame, the determination result of “there is an obstacle” is output.

  This is because it is rare that the number of reflection points in the deceleration area due to snow or rain becomes the same value for two consecutive frames. If it is determined that there is no obstacle in the frame next to the frame that is determined to be “obstacle”, the determination of the previous frame may be an erroneous determination. The judgment result “No obstacle” is output.

(Fourth embodiment)
FIG. 5 is a simplified top view of an obstacle determination apparatus according to the fourth embodiment of the present invention.
The distance measuring device 2 of the obstacle determination device 1 configured as an autonomous traveling device is provided near the center on the upper surface of the obstacle determination device 1 as illustrated, and is not provided at the end. For example, there is a distance from the front end of the bumper 5 provided at the front of the obstacle determination device 1 to the distance measuring device 2. It is not assumed that an obstacle exists in an area inside the contour of the obstacle determination device 1 when viewed from directly above.

  Therefore, the obstacle determination device 1 according to the fourth embodiment provides a predetermined region where the presence / absence of an obstacle is determined outside the outline of the obstacle determination device 1 when viewed from directly above. By providing the predetermined area on the outside of the obstacle determination device 1 in this manner, when there is an obstacle, for example, from the distance measurement device 2 such as a position from the distance measurement device 2 to the front end of the obstacle determination device 1. Close reflection points can be ignored. Since it is not assumed that there is an obstacle as described above at such a close position, it is clear that the reflection point at that position is not a reflection point due to the obstacle, so it is effective to ignore it. Also, at a close position such as several tens of centimeters, multiple reflection points are detected even for small objects such as snow and raindrops, so the reflection points are ignored within a range that does not affect the determination of the presence or absence of obstacles. Is effective.

(Fifth embodiment)
In the above embodiment, the estimation part 31c made all the reflection points in a predetermined area | region the determination object whether it is a noise point.
However, the reflection point from the raindrop tends to be easily detected when the raindrop is located at a short distance of 1 to 3 m from the distance measuring device 2. For this reason, when the reflection point exists at a position of 0 to 1 m from the distance measuring device 2 or at a position away from 3 m, it is not necessary to determine whether or not the reflection point is due to raindrops.
In addition, the closer the snow particles are, the easier it is to detect the reflected light of the laser beam, so it becomes easier to detect the reflected points due to the snow particles, but the reflected light is difficult to detect if the snow particles are separated. Is difficult to detect. For this reason, when the reflection point exists at a position separated from the distance measuring device 2 by a predetermined distance or more, it is not necessary to estimate whether or not the reflection point is caused by snow particles.

Therefore, in the fifth embodiment, the estimation unit 31c sets only a reflection point in a predetermined area that exists at a specific position as a determination target as to whether or not it is a noise point.
Thereby, the processing amount concerning estimation can be reduced.
The specific position is, for example, a position 1 to 3 m from the distance measuring device 2 and a position at which the distance measuring device 2 can receive reflected light from the snow particles so that it can be detected as a reflection point.

(Sixth embodiment)
As described above, the estimation unit 31c employs an estimation method in which a reflection point in a predetermined region is estimated as a noise point when no other reflection point exists within a predetermined distance in the same frame.
However, depending on the distance measuring device 2, the interval of the irradiation angle of the laser beam at the time of scanning is fine, and a plurality of reflection points may be detected from one snow particle or one rain particle. In this case, the noise point cannot be appropriately estimated by the above-described estimation method.

Therefore, in this embodiment, the estimation unit 31c estimates that the reflection point to be estimated is a noise point when the following condition is satisfied.
The condition is that the reflection point to be estimated constitutes a group of reflection points within a first predetermined distance (for example, 20 mm) together with other reflection points. It is a condition that there is no other reflection point within a second predetermined distance (for example, 1 m) other than the reflection point.

  Thereby, even when the interval of the laser irradiation angle of the distance measuring device 2 is fine and a plurality of reflection points are detected from one snow particle or the like, the noise point can be estimated appropriately.

  The technical features (components) described in each of the above embodiments can be combined with each other, and new technical features can be formed by combining them.

DESCRIPTION OF SYMBOLS 1 ... Obstacle determination apparatus, 2 ... Distance measuring device, 21 ... Drive control part, 22 ... Light emission part, 23 ... Optical mechanism part, 24 ... Light receiving part, 25 ... Distance calculation part, 3 ... Main-body part, 31 ... Obstacle Determination unit, 31a: Reflection point position storage unit, 31b ... Reflection point count unit, 31c ... Estimation unit, 31d ... History storage unit, 32 ... Main body operation control unit, 33 ... Drive control unit, 34 ... Drive unit, 4 ... Wheel 5 ... Bumper.

Claims (6)

A distance measuring device that emits a distance measuring electromagnetic wave for a predetermined range, and measures a distance to a reflection point by a reflected wave for each predetermined period;
An obstacle determination device comprising: an obstacle determination unit that determines the presence or absence of an obstacle based on the number of reflection points in a predetermined area provided within the predetermined range, detected during the predetermined period. Because
The obstacle determination unit
An estimation unit that estimates a noise point that is a reflection point due to precipitation among the reflection points in the predetermined region;
A history storage unit that stores a history of the number of reflection points estimated to be the noise points in the predetermined area for each predetermined period;
An obstacle determination device, wherein the presence or absence of the obstacle is determined based on the number of reflection points in the predetermined area in the predetermined period to be determined and the history.   The obstacle determination unit has a predetermined nearest period as the number of the reflection points in the predetermined area in the predetermined period of the determination target and the number of reflection points estimated to be the noise points in the predetermined period. The obstacle determination device according to claim 1, wherein presence / absence of the obstacle is determined based on a number having the highest frequency of occurrence of the obstacle.   The obstacle determination unit is a predetermined nearest period of the number of the reflection points in the predetermined area in the predetermined period of the determination target and the number of reflection points estimated to be the noise points in the predetermined period. The obstacle determination device according to claim 1, wherein presence / absence of the obstacle is determined based on an average value of the obstacle.   The obstacle determination device according to any one of claims 1 to 3, wherein the obstacle determination unit outputs the determination result when the determination result that there is an obstacle is continued twice.   The obstacle determination apparatus according to claim 1, wherein the predetermined area is provided outside the obstacle determination apparatus. The said estimation part makes only the thing which exists in a specific position among the reflective points in the said predetermined | prescribed area | region as the determination object whether it is the said noise point, The any one of Claims 1-5 characterized by the above-mentioned. The obstacle determination apparatus according to item 1.

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