JP5712900B2 - Peripheral object detection device - Google Patents

Description

  The present invention relates to a peripheral object detection device that uses a radar sensor to detect a peripheral object based on past detection results of a peripheral object around a vehicle and the current detection result.

  In various driving assistances such as generation of a route that avoids an obstacle and prevention (reduction) of collision with the obstacle, it is important to detect the obstacle with high accuracy without delay. In Patent Document 1, an obstacle is detected using a radar sensor, a safe area in which no interference between a traveling route candidate of the own vehicle and an obstacle around the own vehicle is assumed, and driving is permitted based on the safe area. It describes that an area is set.

JP 2011-131838 A JP-A-10-124799

  In the obstacle detection method, in order to take into account past obstacle detection results, an obstacle map (grid map showing the existence probability of obstacles) obtained at regular intervals is accumulated and the latest obstacles are stored. There is a method of generating a final obstacle map by superimposing an object map and a past obstacle map. When a new object is detected by the radar sensor in a direction in which no object has been detected in the past by the radar sensor, the existence probability in that direction is 0 in the past obstacle map. The probability of existence for a newly detected object with the probability added is reduced. As a result, a new object is detected by the radar sensor, but it is not detected as an obstacle immediately after detection, and there is room for improvement in terms of early detection timing of the obstacle.

  Therefore, an object of the present invention is to provide a peripheral object detection device that improves detection performance in peripheral object detection using a radar sensor.

  A peripheral object detection device according to the present invention is a peripheral object detection device that uses a radar sensor to detect a peripheral object based on past detection results of the peripheral object around the vehicle and the current detection result. Based on the sensor information, the detection direction information acquisition means for acquiring information on the direction in which the peripheral object is detected and the direction in which the peripheral object is not detected, and the reliability for each direction information acquired by the detection direction information acquisition means. A reliability granting means for granting, and a peripheral object detection means for detecting information on peripheral objects based on the information on each direction acquired by the detection direction information acquisition means and the reliability given by the reliability granting means. The degree of imparting means is characterized in that the degree of reliability given to the information in the direction in which the peripheral object is not detected is lower than the degree of reliability given to the information in the direction in which the peripheral object is detected.

  In this peripheral object detection device, each direction is scanned by a radar sensor at predetermined time intervals, and sensor information (particularly, information about reflection points) in each direction is detected. In the peripheral object detection device, the detection direction information acquisition unit acquires information on each direction (direction in which the peripheral object is detected, direction in which the peripheral object is not detected) scanned by the radar sensor using the sensor information. To do. Further, in the peripheral object detection device, the reliability providing unit assigns reliability to the information in each direction scanned by the radar sensor. At this time, since the information on the direction in which the peripheral object is detected is detected by the radar sensor and is reliable information, high reliability is given. On the other hand, since the information on the direction in which the peripheral object is not detected is not detected by the radar sensor, a reliability lower than that is given. In the peripheral object detection device, the peripheral object information is detected at predetermined time intervals based on information on each direction scanned by the radar sensor and the reliability assigned thereto. Further, the peripheral object detection device acquires the final detection result of the peripheral object based on the current detection result obtained every predetermined time and the past detection results obtained up to the previous time. At this time, since the low reliability is set for the information in the direction in which the peripheral object is not detected (the direction in which the reflection point cannot be obtained by the radar sensor), the peripheral object is not detected in the past detection result. The degree to which the information about the direction is taken into account becomes low (not easily affected). As a result, if a new object is detected by the radar sensor in the direction in which no surrounding object was detected in the past (a reflection point was obtained), the final surroundings based on the current detection result and the previous detection result Even if an object detection result is generated, a newly detected object can be obtained as a final peripheral object detection result without delay. As described above, in the peripheral object detection device, the past detection result is obtained by assigning a lower reliability to the information in the direction in which the peripheral object is not detected than the reliability in the information in the direction in which the peripheral object is detected. The detection performance (especially the detection timing) is improved in the detection of peripheral objects that take into account.

  In the peripheral object detection apparatus of the present invention, the detection direction information acquisition unit may acquire the existence probability of the peripheral object, and the reliability providing unit may provide the reliability with respect to the presence probability of the peripheral object.

  In this peripheral object detection device, the detection direction information acquisition unit acquires the existence probability of the peripheral object in each direction scanned by the radar sensor at every predetermined time. In the peripheral object detection device, the reliability providing unit assigns reliability to the existence probabilities for the respective directions scanned by the radar sensor. In this case, since the low reliability is set for the existence probability (lowest existence probability) of the direction in which no surrounding object is detected, the direction in which the surrounding object has not been detected in the past detection result is the most. The degree to which a low existence probability is taken into account is reduced. As a result, when a new object is detected by the radar sensor in a direction in which no surrounding object has been detected in the past, a final detection result of the surrounding object is generated based on the current detection result and the past detection result. However, the probability of existence with respect to a newly detected object is unlikely to be low, and a newly detected object can be obtained as a final peripheral object detection result without delay.

  In the above peripheral object detection device of the present invention, the radar sensor is preferably a laser radar.

  According to the present invention, the information in the direction in which the peripheral object has not been detected is given a reliability lower than the reliability in the information in the direction in which the peripheral object has been detected, thereby taking into account past detection results. Detection performance (particularly detection timing) is improved in object detection.

It is a block diagram of the obstruction detection apparatus which concerns on this Embodiment. It is an example of a shielding origin reliability model. It is a relationship figure of shielding origin reliability and existence probability. It is an example of an obstacle map. It is a flowchart which shows the flow of a process in EUC which concerns on this Embodiment.

  Embodiments of a peripheral object detection device according to the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected about the element which is the same or it corresponds in each figure, and the overlapping description is abbreviate | omitted.

  In the present embodiment, the peripheral object detection device of the present invention is applied to an obstacle detection device mounted on a vehicle. The obstacle detection device according to the present embodiment is active sensing using laser radar, and is an object that obstructs the running of the host vehicle (for example, a vehicle, a motorcycle, a bicycle, a pedestrian, a fallen object from the vehicle, Detects obstacles related to road construction, and displays obstacle maps that indicate the existence probability of the detected obstacles to prevent collisions with various driving support devices (for example, devices that generate routes to avoid obstacles and obstacles) ) Device). The obstacle detection device according to the present embodiment is finally provided by superimposing the obstacle map of the latest (current) frame and the obstacle map of the past frame at regular intervals (for each frame). An obstacle map is generated.

  The obstacle detection apparatus 1 according to the present embodiment will be described with reference to FIGS. FIG. 1 is a configuration diagram of an obstacle detection apparatus according to the present embodiment. FIG. 2 is an example of a shielding-derived reliability model. FIG. 3 is a relationship diagram between the shielding-derived reliability and the existence probability. FIG. 4 is an example of an obstacle map.

  The obstacle detection device 1 generates, for each frame, three-dimensional point cloud data composed of reflection point (detection point) information using radar information from the laser radar, and each of the laser radars based on the three-dimensional point cloud data. An existence probability in the scan direction is calculated, an obstacle map indicating the existence probability is generated, and a final obstacle map is generated by superimposing the obstacle map of the latest frame and the obstacle map of the past frame. In particular, in the obstacle detection apparatus 1, in order to detect a newly appearing obstacle with high performance, reliability is given to the existence probability in each scan direction, and the reflection point is not obtained. A small reliability is given to the existence probability. In this embodiment, the reflection point by the laser radar is handled as three-dimensional, but it may be handled in two dimensions in the horizontal direction with a constant height.

  The obstacle detection apparatus 1 includes a laser radar 10, an ECU [Electronic Control Unit] 20 (a distance measurement unit 21, an existence probability calculation unit 22, an obstacle map generation unit 23, an obstacle map superposition unit 24, an existence probability model database 25. A shielding-derived reliability model database 26 and a time-derived reliability model database 27).

  In the present embodiment, the laser radar 10 corresponds to the radar sensor described in the claims, and the distance measuring unit 21, the existence probability calculating unit 22, and the existence probability model database 25 are detected in the claims. It corresponds to direction information acquisition means, the existence probability calculation unit 22 and the shielding-derived reliability model database 26 correspond to reliability provision means described in the claims, and an obstacle map generation unit 23 and an obstacle map superposition unit Reference numeral 24 corresponds to the peripheral object detection means described in the claims.

  The laser radar 10 is a radar sensor and detects an object using laser light. The laser radar 10 is attached to the center of the front end of the host vehicle. The laser radar 10 has a mechanism for rotating a light emitting part and a light receiving part of a laser beam in a horizontal direction and a vertical direction. In the laser radar 10, the light emitting unit and the light receiving unit are rotated in the horizontal direction and the light emitting unit and the light receiving unit are rotated in the vertical direction for each frame (at regular time intervals), and laser light is emitted in each scanning direction and reflected. The received laser beam is received. As a scanning method, for example, there are a method in which the direction angle on the center line of the vehicle is 0 ° and the direction is changed by a certain angle, and a method in which the direction is changed at a smaller angle near the center line. In the laser radar 10, information about each reflection point (each detection point) that can be received for each frame (horizontal scan direction angle, vertical scan direction angle, emission time, light reception time, light reception intensity (reflection) The radar signal consisting of intensity) is transmitted to the ECU 20. By the way, for each direction where reflection is not obtained, there is no object or there is an object, but whether the radar light reflected by the relative angle relationship between the object and the laser beam could not be received by the laser radar 10 or not. I do not know. In the two-dimensional case, the laser radar 10 scans only in the horizontal direction, and only the horizontal scanning direction angle is obtained from the reflection point information. Moreover, although it is set as the structure provided with the one laser radar 10, it is good also as a structure provided with the several laser radar 10. FIG.

  The ECU 20 is an electronic control unit including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and comprehensively controls the obstacle detection apparatus 1. The ECU 20 loads the application program for the obstacle detection device 1 stored in the ROM into the RAM and executes it by the CPU, thereby executing the distance measuring unit 21, the existence probability calculating unit 22, the obstacle map generating unit 23, the obstacle Each processing unit of the map superposition unit 24 is configured, and an existence probability model database 25, a shielding-derived reliability model database 26, and a time-derived reliability model database 27 are constructed in advance. The ECU 20 receives a radar signal from the laser radar 10 for each frame, performs processing in each of the processing units 21, 22, 23, and 24, and transmits an obstacle map to the driving support device.

  The distance measurement unit 21 obtains the distance to the reflection point by dividing the speed of the laser beam by the time difference between the emission time and the light reception time for each reflection point included in the radar signal. Since the information of each reflection point includes a horizontal scanning direction angle and a vertical scanning direction angle (information on the direction in which the object can be detected), the obtained distance is determined based on the position of the laser radar 10 as the origin. As a distance to an object in a direction (direction in which the object can be detected) composed of a horizontal scanning direction angle and a vertical scanning direction angle. Here, three-dimensional group data consisting of distance information (relative position with respect to the laser radar 10) in the direction of each reflection point for all reflection points is obtained. Incidentally, this distance information cannot be obtained in the direction in which the reflection point is not obtained by the laser radar 10 (the direction in which the object cannot be detected).

  The existence probability calculation unit 22 calculates the existence probability in the direction in which the reflection point exists for each reflection point included in the three-dimensional group data obtained by the distance measurement unit 21. In this calculation, an existence probability model is extracted from the existence probability model stored in the existence probability model database 25 according to the distance of the reflection point, and the distance (position) of the reflection point is extracted using the extracted existence probability model. Is used to calculate the existence probability at each distance (each position) in the direction in which the reflection point exists. The existence probability model stored in the existence probability model database 25 is prepared for each distance from the laser radar 10 (origin) (for example, every 1 m, 3 m, 5 m, and 10 m). As the existence probability model, for example, a model in which the existence probability is normally distributed with the position of the reflection point as the center (the existence probability is the maximum), the existence probability of the position of the reflection point is the maximum, and the existence probabilities of the other positions are the minimum. There is a model. The existence probability is represented by, for example, 1 (maximum) to 0 (minimum), 100 [%] (maximum) to 0 [%] (minimum). By the way, when a normal distribution existence probability model is used, it is possible to set an existence probability that suppresses noise and reflection point variation when detecting a reflection point.

  Further, the existence probability calculation unit 22 sets the existence probability in a direction other than the direction in which the reflection point included in the three-dimensional group data exists in the detection range of the laser radar 10 (that is, the direction in which no reflection point exists). Here, a minimum value is set as the existence probability in a direction where there is no reflection point.

  Further, the existence probability calculation unit 22 gives a reliability derived from shielding to the existence probability in each direction. Here, a shielding-derived reliability model is extracted from the shielding-derived reliability model stored in the shielding-derived reliability model database 26 according to the presence or absence of a reflection point, and each direction is determined according to the extracted shielding-derived reliability model. The reliability derived from shielding is given to the existence probability in. The reliability is represented by a value of 1 to 0, with 1 being the highest reliability and 0 being the lowest reliability.

  FIG. 2 shows an example of the shielding-derived reliability model, in which the horizontal axis represents the distance with the position of the laser radar 10 as the origin, and the vertical axis represents the shielding-derived reliability. In FIG. 2, the distance indicated by the broken line B1 is the maximum detection distance of the laser radar 10, and the broken line B2 is the distance to the reflection point RP as a sample. The shielding-derived reliability model indicated by reference numeral S1 is a reliability model when a reflection point exists (when an object exists), and indicates that no object exists from the laser radar 10 to the point before the reflection point (object). Since it is possible to believe 100%, the maximum value of 1 is set as the reliability, and since the back side of the reflection point (object) is shielded by the object and it is not known whether the object exists, the lower limit ( This is a model in which the value is very close to 0 and may be 0), and the reliability is changed from the maximum value to the lower limit value based on the position of the reflection point (object). The shielding-derived reliability model indicated by reference sign S2 is a reliability model when there is no reflection point (when there is no object or there is an object but it is unknown whether reflected light has not returned to the laser radar 10), Since the situation is unknown and the reliability is low, this is a model in which a certain low value is set as the reliability. As this low reliability, for example, a value slightly higher than the lower limit of reliability (1.1 times the lower limit, etc.) is used.

  In addition to assigning the shielding-derived reliability to the existence probability in each direction, the existence probability may be calculated by adding the shielding-derived reliability to the existence probability at each position in the direction. . For example, as shown in FIG. 3, in the case of the existence probability (existence probability of normal distribution) P in the direction in which the reflection point exists and the reliability S given to the existence probability in that direction, each position in that direction ( When the existence probability of each distance) is multiplied by the reliability, the existence probability of the normal distribution is dulled before and after the reflection point, and the existence probability changes more gently than the convex shape of the normal distribution.

  The obstacle map generation unit 23 pastes the existence probability and the reliability on each grid of the grid map using the existence probability in each direction calculated by the existence probability calculation unit 22 and the assigned shielding-derived reliability, and the obstacle map Is generated. The obstacle map is a map made up of a large number of grid-like grids formed on a plane set on the left and right and the front with respect to the position of the laser radar 10, and at least the existence probability is pasted on each grid. In the obstacle map, the higher the existence probability of the grid, the higher the possibility that an obstacle exists at that position. The obstacle map may be a single map or a plurality of maps corresponding to each direction in the vertical direction. FIG. 4 shows an example of the obstacle map GM. When the existence probability of the normal distribution is calculated around the position of the reflection point in a certain direction D where the reflection point exists, the obstacle map GM A large existence probability and a large shielding-derived reliability are pasted on the grid G1, and a smaller existence probability and a small shielding-derived reliability are pasted on the grids G2 and G3 before and after the grid G1, and the existence probability in the direction D is 0. The existence probability of 0 and the maximum shielding-derived reliability are pasted to each grid corresponding to the front side of the reflection point, and the existence probability in the direction D is 0 and 0 to each grid corresponding to the rear side of the reflection point. The existence probability and the shielding-derived reliability of the lower limit value are pasted. However, when the shielding-derived reliability falls below a certain threshold, the existence probability of the grid is handled as 0.5 (an area where it is unknown whether there is an object). When the latest obstacle map is generated for each frame, the obstacle map generation unit 23 stores the obstacle map in a predetermined area of the RAM in the ECU 20. The accumulated obstacle maps are used in the obstacle map superposition unit 24, and obstacle maps for the past number of frames used in the obstacle map superposition unit 24 are sequentially accumulated. If the existence probability calculation unit 22 calculates the existence probability taking into account the shielding-derived reliability with respect to the existence probability at each position, the existence probability with the shielding-derived reliability taken into account is calculated on the grid map. Paste to each grid.

  The obstacle map superimposing unit 24 superimposes the latest obstacle map generated by the obstacle map generating unit 23 and the accumulated obstacle maps of several past frames (or several tens of frames), An obstacle map to be finally provided is generated. Here, a time-derived reliability model is extracted from the time-derived reliability models stored in the time-derived reliability model database 27, and according to the reliability of each time frame of the extracted time-derived reliability model, The existence probability is calculated by adding the existence probability of the corresponding grid in the obstacle map of each past frame to the existence probability of each grid of the latest obstacle map. As the time-derived reliability model stored in the time-derived reliability model database 27, for example, a model in which the degree of consideration is reduced as the past frame is reduced (the latest frame has the highest reliability and the most past frame has the lowest reliability). Model). Further, since the shielding-derived reliability is attached to each grid in the obstacle map, the existence probability is calculated in consideration of the shielding-derived reliability in the calculation of the existence probability for each grid. Therefore, the final existence probability using the latest frame existence probability, time-derived reliability, and shielding-derived reliability, and the past frame existence probability, time-derived reliability, and shielding-derived reliability, for each grid. And the existence probability is pasted on each grid of the obstacle map.

Here, by introducing the reliability derived from shielding, when a reflection point is obtained in the latest frame in the direction where the reflection point was not obtained in the past, the reflection point is obtained in the final obstacle map. An example of a high existence probability in a grid at a certain position is shown. In this example, in order to simplify the explanation, only one frame is used as the past frame used for the overlay process, and the time-derived reliability of the latest frame and the past frame is both 1 (therefore, in the following equation, The time-derived reliability is omitted). In the latest frame, since the reflection point is obtained, the grid-derived reliability C ₁ of the grid at the position of the reflection point is set to 1, and the existence probability P _{1 is set} to 1. In the past frame, since no reflection point is obtained, the shielding-derived reliability C ₀ of the corresponding grid is set to 0.05, and the existence probability P _{0 is set} to 0. In this case, the final existence probability of the grid is ((P ₀ × C ₀ ) + (P ₁ × C ₁ )) / (C ₀ + C ₁ ) = about 0.95 in the calculation of the overlay process. . In this way, a high existence probability can be obtained immediately after a new reflection point is detected, and it is detected as an obstacle without delay. However, conventionally, since the reliability derived from shielding is not taken into consideration, in the case of the above example, the superposition processing is performed by setting both C ₁ and C ₀ to 1. In this case, the final existence probability of the grid is ((P ₀ × C ₀ ) + (P ₁ × C ₁ )) / (C ₀ + C ₁ ) = 0.5 in the calculation of the overlay process. Thus, a low existence probability is obtained immediately after a new reflection point is detected, and the existence probability gradually increases each time frames are overlapped, and is detected as an obstacle with a delay.

  As described above, since the obstacle detection apparatus 1 has a low shielding-derived reliability for the direction in which the reflection point has not been obtained in the past (the object has not been detected), In the obstacle map, the degree to which the existence probability 0 in the direction in which the reflection point is not obtained is taken into consideration is low (it is difficult to be affected by the existence probability 0). As a result, when a new reflection point is obtained by the laser radar 10 in a direction in which no reflection point has been obtained in the past, the final obstacle is determined based on the obstacle map of the latest frame and the obstacle map of the past frame. Even if the object map is generated, it is possible to obtain a final obstacle map having a high existence probability at a newly obtained reflection point without delay.

  With reference to FIGS. 1-4, the operation | movement in the obstruction detection apparatus 1 is demonstrated. In particular, processing in the ECU 20 will be described along the flowchart of FIG. FIG. 5 is a flowchart showing the flow of processing in the EUC according to the present embodiment. The obstacle detection apparatus 1 repeatedly performs the operations described below for each frame.

  The laser radar 10 emits laser light and receives the reflected light in each horizontal scanning direction and vertical scanning direction for each frame. The laser radar 10 transmits information about each reflection point that has been received as a radar signal to the ECU 20.

  For each frame, the ECU 20 measures (calculates) the distance to each reflection point detected by the laser radar 10 based on the received radar signal (S1). Here, three-dimensional group data consisting of information on reflection points detected in the latest frame is obtained.

  In the EUU 20, for each reflection point included in the three-dimensional group data, an existence probability model is extracted from the existence probability model database 25 according to the distance to the reflection point, and the reflection point is obtained using the existence probability model. The existence probability in the direction is calculated (S2). Further, the EUU 20 extracts a shielding-derived reliability model from the shielding-derived reliability model database 26 according to the presence / absence of a reflection point, and uses the shielding-derived reliability model for the existence probability in each direction. (S2). Here, the existence probability taking into account the shielding-derived reliability may be calculated. Then, the ECU 20 generates the latest obstacle map using the existence probability and reliability in each direction (S3). Further, the ECU 20 stores the latest obstacle map (S4).

  The ECU 20 extracts the time-derived reliability model from the time-derived reliability model database 27, and uses the latest obstacle map and the accumulated obstacle maps of the past frames for each time frame of the time-derived reliability model. The final obstacle map is generated by superimposing according to the time-derived reliability and the shielding-derived reliability of each grid (S5). Then, the ECU 20 transmits the final obstacle map to the driving support device.

  According to the obstacle detection apparatus 1, the detection performance of the obstacle is improved by introducing the shielding-derived reliability and imparting the shielding-derived reliability to the existence probability in each direction. In particular, according to the obstacle detection device 1, by setting the shielding-derived reliability for the existence probability (minimum value 0) in the direction where the reflection point is not obtained by the laser radar 10 to a low value, a new value is obtained in that direction. When the reflection point is obtained, the existence probability after the superimposition process can be increased immediately after the reflection point is obtained, and the obstacle can be detected without delay.

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the present invention is applied to an obstacle detection device that obstructs the running of the host vehicle. However, a pedestrian detection device that detects a pedestrian around the host vehicle and an other vehicle detection device that detects a vehicle around the host vehicle The present invention can also be applied to other peripheral object detection devices.

  In this embodiment, laser radar is applied as a radar sensor, but other radar sensors such as millimeter wave radar may be applied.

  In the present embodiment, the final obstacle map is generated by superimposing the past obstacle map and the latest obstacle map. However, the past detection results of the surrounding objects and the latest (this time) are used. Other methods may be used as a method of detecting the peripheral object based on the detection result of.

  In the present embodiment, the existence probability is used as the obstacle presence information, but other information may be used. For example, there is 0/1 information indicating whether or not it exists.

  DESCRIPTION OF SYMBOLS 1 ... Obstacle detection apparatus, 10 ... Laser radar, 20 ... ECU, 21 ... Distance measurement part, 22 ... Existence probability calculation part, 23 ... Obstacle map production | generation part, 24 ... Obstacle map superimposition part, 25 ... Existence probability Model database, 26 ... shielding-derived reliability model database, 27 ... time-derived reliability model database.

Claims (2)

A surrounding object detection device that detects a surrounding object based on a past detection result of a surrounding object around the vehicle and a current detection result using a radar sensor,
Detection direction information acquisition means for acquiring information on a direction in which a peripheral object is detected based on sensor information from the radar sensor and a direction in which the peripheral object is not detected;
A reliability providing unit that provides reliability to the information in each direction acquired by the detection direction information acquiring unit;
Peripheral object detection means for detecting information on peripheral objects based on the information of each direction acquired by the detection direction information acquisition means and the reliability given by the reliability provision means;
With
The reliability applying means, the reliability to be applied to the direction of the information is not detected around the object, and lower reliability than the reliability of imparting the direction information detected peripheral object,
The detection direction information acquisition means acquires the existence probability of a peripheral object,
The surrounding object detection apparatus, wherein the reliability providing unit provides a reliability with respect to the existence probability of the surrounding object. The peripheral object detection apparatus according to claim 1, wherein the radar sensor is a laser radar.

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