JP7324057B2 - Vehicle object detection device - Google Patents

Description

The present invention relates to a vehicle object detection device that detects an object existing around a vehicle using a radar device.

Vehicles such as automobiles are equipped with cameras and radar equipment to detect objects existing outside the vehicle, avoid collisions with obstacles in front, follow-up control for preceding vehicles, and provide warning control and steering for vehicle sway and lane departure. Systems that execute various types of support control for drivers, such as control, have been put into practical use, and automatic driving systems that do not require driver's driving operations are being put into practical use.

In particular, radar devices are less affected by weather conditions such as rain, snow, and fog, and backlight, compared to image sensors such as cameras that use visible light and infrared light. It is considered to be a promising sensor for detecting objects in the external world.

However, the radar apparatus has a problem in that, due to the shift in the direction of the time axis of the radio waves, a ghost is generated, which makes it appear as if an object exists even though the object does not actually exist. It is necessary to reliably discriminate between the object and the actual object.

For this reason, for example, in Patent Document 1, a radar beam is scanned substantially parallel to a road surface on which a vehicle is traveling, and an object within the radar beam scanning range is detected in each radar beam scanning once or twice or more. , proposes a technology for determining whether or not a first detected object, which is a detected object on one's own lane on a road surface, is a ghost, based on a second detected object, which is a detected object on an adjacent lane adjacent to one's own lane. It is

JP-A-2000-147115

Patent Document 1 uses the distance and relative speed between the second detection object and the first detection object, the angle formed by the respective azimuths, etc. as necessary conditions to determine whether the first detection object is a ghost. The condition is that the second sensed object is a real object that actually exists.

However, when the first detection object is a real object, the radar wave reflected by the first detection object, which is a real object, is reflected by another object, and the reflected wave is reflected again by the first detection object. Multipath reception by the apparatus may occur, and it may be difficult to distinguish whether the second detected object is a real object or a ghost.

In other words, if there is another object in the driving environment of the vehicle that generates multipath for the radar reflected wave from the detection target, the ghost may be erroneously detected as an actual object due to its influence. Conversely, there is a possibility that an actual object may be erroneously determined to be a ghost and removed, which may seriously hinder vehicle travel control.

The present invention has been made in view of the above circumstances, and eliminates the influence of other objects that generate multipaths on the radar reflected waves from the detection target when detecting an object outside the vehicle with a radar device, It is an object of the present invention to provide a vehicle object detection device capable of reliably distinguishing between a ghost and a real object.

A vehicle object detection device according to one aspect of the present invention transmits a radar transmission wave from a radar device, receives a reflected wave reflected by an object, and detects an object existing behind a vehicle. A detection device, wherein a reflection point is set in advance as a reflection point capable of reflecting a radar wave reflected by the first object at a position opposite to the first object detected by the radar device with the host vehicle interposed therebetween . a reflection point judgment unit for judging whether or not a predetermined object exists based on driving environment information around the own vehicle ; a first ghost condition for provisionally making the second object a ghost when an object is detected , based on the relative velocity of the first object with respect to the reflection point and the relative velocity of the second object with respect to the reflection point; is established, and if the relative velocity of the second object with respect to the reflection point is substantially equal to twice the relative velocity of the first object with respect to the reflection point, then the first ghost condition is established a first ghost determination unit that determines , and when the first ghost condition of the second object is satisfied , based on the condition of the distance between the reflection point, the host vehicle, the first object, and the second object; Then, it is determined whether or not a second ghost condition for finally making the second object a ghost is satisfied, and the distance from the host vehicle to the first object and the distance from the reflection point to the first object are determined. is substantially equal to the distance from the host vehicle to the second object, the second ghost determination unit determines that the second ghost condition is satisfied and removes the second object.

According to the present invention, when an object outside the vehicle is detected by a radar device, the effects of other objects that generate multipaths to the radar reflected waves from the detection target are eliminated, and ghosts and real objects are reliably detected. can be identified.

Configuration diagram of vehicle object detection device Explanatory diagram showing the influence of forward objects on radar waves to the rear of the vehicle Explanatory diagram showing the positional relationship between the own vehicle, the following vehicle, the forward object, and the approaching vehicle. Ghost Judgment Routine Flowchart

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an object detection device for a vehicle. A vehicle object detection device 1 shown in FIG. It is configured to be connected for two-way communication via.

The radar device 10 uses, for example, a millimeter wave as a radar transmission wave, and detects the relative speed, distance, and direction of an object existing around the own vehicle with respect to the own vehicle by a known FMCW (Frequency Modulated Continuous Wave) method or pulse method. do. The radar device 10 includes, for example, a plurality of radar units 11, and each radar unit 11 is arranged at a plurality of locations on the vehicle. FIG. 1 shows an example in which the radar device 10 has four radar units 11 .

The radar unit 11 combines or integrates a transmitting antenna for radiating a radar transmission wave into space and a receiving antenna for receiving a reflected wave that is returned after the radar transmission wave is reflected by an object. It has become. The radar units 11 are arranged, for example, at the left and right corners of the front and rear bumpers of the vehicle.

In the radar device 10, the distance to an object can be calculated, for example, based on a signal processing algorithm based on the time difference between radar transmission waves and reception waves. In addition, the velocity (relative velocity) of an object can be calculated based on a signal processing algorithm based on the Doppler effect and changes in distance. Furthermore, the orientation of an object can be calculated based on a signal processing algorithm using the amplitude and phase of received waves. The processing for calculating the distance, speed, and direction of an object using such a radar device 10 can be performed using a general algorithm, and detailed description thereof will be omitted here.

The driving environment detection device 20 includes a locator unit 21 that detects the vehicle position of the vehicle based on signals from a plurality of navigation satellites such as GNSS (Global Navigation Satellite System) satellites, and processes an image of the surroundings of the vehicle. and an image processing unit 22 for recognizing the external environment.

The locator unit 21 receives signals containing information about orbits and times transmitted from a plurality of navigation satellites, and based on the received signals, the self-position of the own vehicle, including longitude, latitude, altitude, and time information. Measure as an absolute position. In addition, when the positioning accuracy deteriorates due to the capture state of signals (radio waves) from satellites or the influence of multipath due to the reflection of radio waves, the locator unit 21 can The vehicle position is measured as a relative positional change.

Furthermore, the locator unit 21 includes a map database DB, and specifies the position on the map data of the map database DB from the position data of the own vehicle that has been positioned. The map database DB is a database that holds high-precision maps created for travel control including automatic driving, and is stored in large-capacity storage media such as HDDs (hard disk drives) and SSDs (solid state drives). .

In detail, a high-definition map is a multi-dimensional map that holds static information such as road shapes and connections between roads, and dynamic information such as traffic information collected by infrastructure communication in multiple layers. (dynamic map). Road data includes types of road white lines, number of lanes, width of lanes, sequence of points data indicating center positions in the width direction of lanes, curvature of lanes, azimuth angles of travel lanes, speed limits, etc. include.

The image processing unit 22 recognizes the external environment around the own vehicle by processing the image captured by the camera unit 22a mounted on the vehicle. As the camera unit 22a, a single monocular camera or a stereo camera composed of two cameras that capture images of the same object from different viewpoints is used.

When a stereo camera is used, the external environment is three-dimensionally recognized by stereo-processing a pair of left and right images captured by the stereo camera. The camera unit 22a as a stereo camera includes, for example, two shutter-synchronized color cameras each having an imaging device such as a CCD or CMOS near the rearview mirror on the inside of the front window in the upper part of the passenger compartment. It is configured to be arranged on the left and right.

A pair of left and right images captured by a stereo camera are subjected to matching processing, and the amount of pixel shift (parallax) at corresponding positions between the left and right images is obtained. Then, the pixel shift amount is converted into luminance data or the like to generate a distance image. Based on the principle of triangulation, the points on the range image are coordinate-transformed into points on the real space centered on the vehicle, and the left and right white lines, obstacles, and lanes of the road on which the vehicle travels are demarcated. A vehicle or the like traveling in front of the vehicle is recognized three-dimensionally.

White lines on the left and right of a road can be recognized by extracting point groups that are candidates for white lines from an image and calculating straight lines and curves that connect the candidate points. For example, in a white line detection area set on an image, edges whose luminance changes more than a predetermined amount are detected on a plurality of search lines set in the horizontal direction (vehicle width direction), and one set of white lines is detected for each search line. By detecting the start point and the white line end point, an intermediate area between the white line start point and the white line end point is extracted as a white line candidate point.

Then, the white line is recognized by processing the time-series data of the spatial coordinate positions of the white line candidate points based on the amount of vehicle movement per unit time and calculating a model that approximates the left and right white lines. As the approximation model of the white line, it is possible to use an approximation model obtained by connecting straight line components obtained by Hough transform, or a model approximating with a curve such as a quadratic equation.

The radar status monitoring device 30 monitors the status of object detection by the radar device 10 based on the information from the driving environment detection device 20, and determines whether the object detected by the radar device 10 is a real object that actually exists or does not actually exist. Determine ghost. Therefore, the radar situation monitoring device 30 includes a reflection point determination section 31 , a first ghost determination section 32 and a second ghost determination section 33 .

Reflection point determination unit 31 detects an object (first object) detected by radar device 10, and determines if there is another object in the running environment of the host vehicle that serves as a reflection point for reflecting the radar wave reflected by the first object. Determine if it exists. For example, when a radar wave is transmitted from the radar unit 11 at the rear of the own vehicle and a following vehicle traveling behind the own vehicle is detected, if there is a reflection point in front of the own vehicle, the reflected wave reflected by the following vehicle is multiplied. A ghost occurs due to the pass, and the possibility of misdetecting the ghost as an actual object increases.

FIG. 2 is an explanatory diagram showing the influence of a forward object on the radar wave to the rear of the own vehicle. In the scene shown in FIG. 2, an object SG serving as a reflection point for reflecting radar waves exists in front of the own vehicle Cs, and a following vehicle as a first object OBJ1 to be detected exists behind the own vehicle Cs. are doing. In such a scene where the object SG (reflection point) exists on the opposite side of the first object OBJ1 across the own vehicle Cs, if a radar wave is transmitted from the radar unit 11 at the rear of the own vehicle Cs, , this radar wave is reflected by the first object (following vehicle) OBJ1, the reflected wave is received by the radar unit 11, and the first object OBJ1 is detected.

At the same time, the reflected wave reflected by the first object OBJ1 travels toward the object SG in front of the vehicle Cs and is reflected by the object SG. The radar wave reflected by the object SG is again reflected by the first object OBJ1 and received by the radar unit 11, causing the radar unit 11 to generate a ghost. Therefore, when the radar unit 11 detects the second object OBJ2 approaching from the rear side of the first object OBJ1, even if the second object OBJ2 is an actual physical object, the second object OBJ2 is an object. The possibility of erroneously determining that it is a ghost generated by the reflected wave of SG and removing it increases.

The reflection point determination unit 31 determines whether or not there is an object as a reflection point that may cause ghosts due to such multipaths in the running environment of the host vehicle. Specifically, the reflection point determination unit 31 displays the destination and the road exit around the vehicle based on the vehicle position information and map information from the locator unit 21 and the image recognition information from the image processing unit 22. It is determined whether or not there is a reflection point that reflects the radar wave, such as a signboard, an upper wall surface of a tunnel, or a preceding vehicle higher than the own vehicle, such as a trailer.

When the reflection point determination unit 31 determines that a reflection point exists and detects a second object following the first object, the first ghost determination unit 32 determines the relative speed of the reflection point with respect to the vehicle and the speed of the reflection point with respect to the vehicle. Based on the relative velocity of the first object and the relative velocity of the second object with respect to the host vehicle, it is determined whether or not a first ghost condition for provisionally making the second object a ghost is satisfied.

In the example of FIG. 2, Vos is the relative velocity between the own vehicle Cs and the object (reflection point) SG, Vrel1 is the relative velocity between the own vehicle Cs and the first object (following vehicle) OBJ1, Vrel1 is the relative velocity between the own vehicle Cs and the second object (following vehicle) OBJ1 Assuming that the relative velocity with respect to the object OBJ2 is Vrel2, it is determined whether or not the first ghost condition shown in the following equation (1) is satisfied within the allowable range set from the velocity resolution of the radar unit 11.
2×(Vos+Vrel1)=Vos+Vrel2→Vos+2×Vrel1=Vrel2 (1)

Equation (1) states that when the relative velocity (Vos+Vrel2) of the second object OBJ2 with respect to the object SG is equal to twice the relative velocity (Vos+Vrel1) of the first object OBJ1 with respect to the object SG, the second object OBJ2 is equal to the first This means that there is a high possibility that the reflected wave from the object OBJ was reflected by the object SG, then reflected again by the first object OBJ1, received by the radar unit 11, and detected. Therefore, the first ghost determination unit 32 provisionally determines that the second object OBJ2 is a ghost when the condition of formula (1) is satisfied. Based on this provisional ghost determination, the second object OBJ2 is removed as noise.

When the first ghost condition for the second object is satisfied, the second ghost determination unit 33 determines whether the second object is really a ghost based on a second ghost condition related to the positional relationship at least in which the second object is detected. To prevent the second object from being mistakenly removed by making a final judgment as to whether or not. The second ghost condition includes, for example, a lane condition in which the second object exists in an area where the vehicle can travel, such as on an adjacent lane adjacent to the lane of the own vehicle, a reflection point, the own vehicle, the first object, and the second object. Mainly the distance condition related to the distance between and, including conditions related to the size of the second object such as trucks and motorcycles, conditions of driving roads such as highways and general roads, etc., weighting these conditions as appropriate and combine.

When judging the lane conditions, the second ghost judgment section 33 acquires the vehicle position information and map information from the locator section 21 and the image recognition information from the image processing section 22, and determines the lane in which the vehicle is currently traveling. Check if there is a lane next to As shown in FIG. 2, when there is an adjacent lane LNr adjacent to the lane LNs of the own vehicle, and the second object OBJ2 is detected on this adjacent lane LNr (lane condition satisfied), the second ghost determination unit 33 determines that the second object OBJ2 is not a ghost but a real object (approaching vehicle) as the second ghost condition is not met. On the other hand, if the adjacent lane does not exist or the second object OBJ2 is outside the adjacent lane (lane condition not satisfied), the second ghost determination unit 33 determines that the second object OBJ2 is a ghost as the second ghost condition is satisfied. to decide.

On the other hand, when judging the distance condition, the second ghost judging section 33 examines the relationship between the distances DB, DS and DE as shown in FIG. FIG. 3 is an explanatory diagram showing the positional relationship among the own vehicle, the following vehicle, the forward object, and the approaching vehicle. In FIG. 3, DB is the distance from the own vehicle Cs to the first object (following vehicle) OBJ1, DS is the distance from the object (reflection point) SG to the first object OBJ1, and DS is the second object (approaching vehicle) from the own vehicle Cs. Assuming that the distance to OBJ2 is DE, the second ghost judgment section 33 determines that the relationship between these distances DB, DS, and DE satisfies the condition of the following equation (2) within the allowable range set from the range resolution of the radar unit 11. to see if you are satisfied with
DS + DB = DE (2)

Equation (2) is the sum of the distance DB from the own vehicle Cs to the first object (following vehicle) OBJ1 and the distance DS from the object (reflection point) SG to the first object OBJ1, that is, from the own vehicle Cs to the first object This means that the path length of the radio wave reflected by OBJ1 and reaching the object SG is equal to the path length of the radio wave from the host vehicle Cs to the second object OBJ2. Therefore, when the first ghost determination unit 32 provisionally determines that the second object OBJ2 is a ghost and the condition of expression (2) is satisfied, the second ghost determination unit 33 determines that the second ghost condition is satisfied. It is determined that the second object OBJ2 is a ghost.

The above lane conditions and distance conditions may be used alone or in combination. However, when a lane condition and a distance condition are combined, priority is given to the lane condition. For example, when the second object is tentatively determined to be a ghost and the lane condition is satisfied, the second object is determined to be a real object regardless of the distance condition, and the lane condition is not satisfied. However, if the distance condition is satisfied, it is determined that the second object is a ghost.

When the second object determination unit 33 finally determines that the second object is a ghost, it removes the data of the second object, and when it finally determines that the second object is not a ghost but a real object. , the data of the first object and the second object are transmitted to a not-shown running control device or the like via the communication bus 100 . The travel control device executes travel control while ensuring safety for objects detected by the radar units 11 of the radar device 10 .

Next, ghost determination processing in the radar condition monitoring device 30 will be described using the flowchart of FIG. FIG. 4 is a flow chart of the ghost determination routine. Although FIG. 4 shows an example of processing when the radar unit 11 monitors the rear area of the vehicle, the same applies to monitoring the front area.

In step S1, the radar condition monitoring device 30 checks whether or not a vehicle behind the host vehicle (rear vehicle) is detected by the radar unit 11 at the rear of the vehicle. If the vehicle behind is not detected, the radar condition monitoring device 30 exits this routine and returns to the processing of step S1 in the next control cycle. move on.

In step S<b>2 , the radar condition monitoring device 30 acquires the position of the rear vehicle (the distance from the own vehicle to the rear vehicle) and the relative speed of the rear vehicle with respect to the own vehicle from the radar unit 11 . Next, proceeding to step S3, the radar condition monitoring device 30 checks whether or not the radar unit 11 detects a moving object (rear approaching object) approaching the own vehicle following the rear vehicle.

If no rearward approaching object is detected in step S3, the radar condition monitoring device 30 exits the routine from step S3 and restarts the process of step S1 in the next control cycle. If an object approaching from behind is detected, the radar condition monitoring device 30 proceeds to the process from step S3 to step S4, and obtains the position of the object from the radar unit 11 (distance from the own vehicle to the object approaching from behind) and the object from the own vehicle. Get the relative velocity of the rear-approaching object to

Next, the radar condition monitoring device 30 advances from step S4 to step S5 to read vehicle position information, map information, and image recognition information from the locator section 21 and image processing section 22 of the driving environment detection device 20 . Based on the vehicle position information, the map information, and the image recognition information, the radar condition monitoring device 30 detects the vehicle ahead of the vehicle, such as a signboard indicating the destination and road exit, the upper wall surface of a tunnel, and a trailer. It is determined whether or not there is a reflection point that reflects the radar wave of a high preceding vehicle or the like.

If no reflection point exists in front of the own vehicle, the radar condition monitoring device 30 proceeds from step S5 to step S9, and determines that the object approaching from behind is an actual object (vehicle approaching from behind). Then, the data of the vehicle approaching from behind is transmitted together with the data of the vehicle behind, and this routine is exited.

On the other hand, if there is a reflection point in front of the vehicle, the radar condition monitoring device 30 proceeds from step S5 to step S6 to determine whether or not the first ghost condition is established to tentatively make the object approaching from the rear a ghost. find out if If the first ghost condition is not satisfied, the radar condition monitoring device 30 advances from step S6 to step S9 to determine that the object approaching from behind is a real object, and transmits the data of the object approaching from behind together with the data of the vehicle behind.

On the other hand, if the first ghost condition is satisfied in step S6, the radar situation monitoring device 30 further checks in step S7 whether or not the second ghost condition is satisfied to determine whether the rearward approaching object is really a ghost. is an entity that exists in As a result, if the second ghost condition is satisfied, the radar condition monitoring device 30 determines that the object approaching from behind is a ghost in step S8 and removes the data. In S9, it is determined that the rearward approaching object is a real object.

As described above, in the present embodiment, it is determined whether or not there is a reflection point for reflecting the radar wave reflected by the first object in the vicinity of the own vehicle with respect to the first object detected by the radar device, When the second object is detected by the radar device after the first object in the presence of the reflection point, the relative velocity of the reflection point with respect to the own vehicle, the relative velocity of the first object with respect to the own vehicle, and the second object with respect to the own vehicle. Based on the relative velocity of the object, it is determined whether or not a first ghost condition for provisionally making the second object a ghost is satisfied. Then, if the first ghost condition for the second object is satisfied, it is determined whether or not the second object is a ghost based on at least the second ghost condition related to the positional relationship in which the second object is detected. As a result, when an object outside the vehicle is detected by the radar device, the effects of other objects that generate multipaths to the radar reflected waves from the detection target are eliminated, and ghosts and real objects are reliably discriminated. be able to.

1 vehicle object detection device 10 radar device 11 radar unit 20 driving environment detection device 21 locator section 22 image processing section 30 radar condition monitoring device 31 reflection point determination section 32 first ghost determination section 33 second ghost determination section

Claims (3)

A vehicle object detection device for detecting an object existing behind the own vehicle by transmitting a radar transmission wave from a radar device and receiving a reflected wave reflected by an object,
A predetermined object preset as a reflection point capable of reflecting the radar wave reflected by the first object exists at a position opposite to the first object detected by the radar device with respect to the own vehicle. A reflection point determination unit that determines whether or not to perform based on the driving environment information around the own vehicle ;
When the radar device detects a second object following the first object while the reflection point exists, the relative speed of the first object with respect to the reflection point and the relative speed of the second object with respect to the reflection point determining whether or not a first ghost condition for tentatively making the second object a ghost is satisfied based on the velocity and the relative velocity of the second object with respect to the reflection point; a first ghost judgment unit that judges that the first ghost condition is satisfied when the speed is approximately twice the relative speed of one object ;
When the first ghost condition for the second object is satisfied, the second object is finally removed based on the distance condition between the reflection point, the host vehicle, the first object, and the second object. the sum of the distance from the own vehicle to the first object and the distance from the reflection point to the first object is determined from the own vehicle and a second ghost determination unit that determines that the second ghost condition is satisfied and removes the second object when the distance to the second object is substantially equal to the distance to the second object. The second ghost determination unit includes, in the second ghost conditions, a condition that the second object is detected behind the vehicle on an adjacent lane adjacent to the lane of the vehicle, and the second object is When detected behind the own vehicle on the adjacent lane, the sum of the distance from the own vehicle to the first object and the distance from the reflection point to the first object is the distance from the own vehicle to the first object. 2. The vehicle object detection device according to claim 1, wherein the second ghost condition is not satisfied and the second object is not removed even if the distance to the two objects is substantially equal. 2. The predetermined object set in advance includes at least one of a signboard indicating a destination and a road exit, an upper wall surface of a tunnel, and a preceding vehicle having a higher vehicle height than the own vehicle. 2. The vehicle object detection device according to 2.

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