JP7122101B2 - Vehicle obstacle detection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle obstacle detection device that detects obstacles present in the direction in which a vehicle travels.

In vehicles such as automobiles, devices and systems that detect obstacles by outputting search waves such as ultrasonic waves and millimeter waves toward an object and examining the reflected waves of the search waves that are reflected by the object are well known. is.

For example, in Patent Document 1, an ultrasonic sensor is used to detect the distance between an obstacle present in the direction in which the vehicle is traveling and the vehicle. A vehicle surroundings monitoring system has been disclosed that notifies a driver of the existence of an object and operates a brake to avoid a collision with an obstacle.

JP 2015-135301 A

However, when the vehicle attitude changes due to the slope of the road surface, such as when reversing from a flat road surface to a sloped road surface, or when reversing from a sloped road surface to a flat road surface, etc., the vehicle stops and the road surface itself may be moved by itself. Even though there is no risk of contact or collision with the vehicle, the object may be erroneously detected as an obstacle that will contact or collide with the own vehicle, leading to false alarms or malfunction of the brakes.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. The object is to provide a detection device.

A vehicular obstacle detection device according to one aspect of the present invention receives a reflected wave of a survey wave emitted from a vehicle and is reflected by an object, and detects an object whose reflection intensity exceeds a predetermined threshold as an obstacle. A vehicular obstacle detection device that detects an obstacle by processing an image captured by a camera of a road surface on which a vehicle is traveling, and determining a relative inclination state of the road surface on which the vehicle is traveling with respect to a reference plane fixed to the vehicle. a height calculation unit that calculates the height of an object on the traveling road surface; and a tilt state determination unit that detects the tilt of the own vehicle with respect to the direction of gravity and determines the tilt state of the reference plane. Then, the movement state of the vehicle is determined from the inclination state of the reference plane and the output state of the driving force based on the accelerator opening of the vehicle. and a detection level adjustment unit that adjusts the detection level of the obstacle by varying the threshold based on the height of the object on the road surface.

ADVANTAGE OF THE INVENTION According to this invention, when detecting the obstacle which exists in the advancing direction of the own vehicle, the erroneous detection of the obstacle resulting from the inclination of a road surface can be prevented.

Configuration diagram of vehicle obstacle detection device Explanatory drawing showing the adjustment of the obstacle detection level when the vehicle reverses from an inclined road surface to a flat road surface. Explanatory drawing showing the adjustment of the obstacle detection level when the vehicle reverses from a flat road surface to a sloping road surface. Explanatory diagram showing the adjustment of the obstacle detection level when there is a three-dimensional object on the sloping road surface Flowchart of obstacle detection processing

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a vehicle obstacle detection device (hereinafter simply referred to as "obstacle detection device") that is mounted on a vehicle such as an automobile and detects an obstacle by emitting a survey wave in the direction of travel of the vehicle. ). In this embodiment, the obstacle detection device 1 uses ultrasonic waves as search waves for detecting obstacles. The situation and obstacles are detected, and information from the acceleration sensor 4 and the accelerator opening sensor 5 is added to detect the external environment and the state of the own vehicle when the vehicle is backing up.

In the following description, one ultrasonic sensor 3 will be described as a representative, but the same applies when a plurality of sensors are provided. Further, as a sensor that emits search waves for detecting obstacles, instead of the ultrasonic sensor 3, a millimeter wave radar or a lidar (LIDAR: Light Detection and Ranging) may be used. Furthermore, the camera 2 may be replaced with a millimeter wave radar or lidar.

The obstacle detection device 1 includes a controller 10 as a control unit that processes information from the camera 2 , ultrasonic sensor 3 , acceleration sensor 4 and accelerator opening sensor 5 . The controller 10 is composed mainly of a microcomputer and is connected to a communication bus 100 forming an in-vehicle network. When the obstacle detection device 1 detects an obstacle that may collide with the vehicle body when the vehicle is moving backward, the obstacle detection device 1 transmits information about the obstacle to an alarm device and a brake device (not shown) from the controller 10 via the communication bus 100, and issues an alarm. and brakes to avoid collisions with obstacles.

At this time, the controller 10 determines the inclination of the road behind the vehicle and the height of the object from the image captured by the camera 2, adjusts the detection level of the ultrasonic sensor 3, and detects objects exceeding the adjusted detection level. By detecting it as an object, it is possible to prevent false alarms and malfunction of the brakes for objects that have no risk of collision. For this reason, the controller 10 includes a road surface inclination determination section 11, a height calculation section 12, an inclination state determination section 13, a detection level adjustment section 14, and an obstacle detection section 15 as functional sections related to obstacle detection.

The road surface inclination determining unit 11 processes the image captured by the camera 2, estimates the relative inclination angle of the road surface behind the vehicle with respect to a reference plane fixed to the vehicle, and determines the inclination state of the road surface behind the vehicle. do. For example, when a stereo camera is used as the camera 2, two cameras are arranged at a predetermined interval to capture images of the same object from different viewpoints. Based on the principle of triangulation, the coordinate values of feature points in a three-dimensional space fixed to the own vehicle are obtained, and a plane formula for approximating the road surface is calculated using statistical processing such as the least squares method or Hough transform. Then, the tilt angle of the plane represented by this plane formula is used as the relative tilt angle of the road surface behind the vehicle with respect to a reference plane that assumes a flat road surface under the vehicle.

The height calculator 12 recognizes an object existing behind the vehicle from the image captured by the camera 2 and calculates the height of the object. For example, when a stereo camera is used as the camera 2, a flat road surface under the vehicle is used as a reference plane, and feature points protruding from the reference plane are extracted. Then, the three-dimensional object is recognized by grouping the extracted feature points, and the projection height H1 of the recognized three-dimensional object from the reference plane is calculated as the height of the object.

The height calculator 12 also calculates the height H2 of the object on the inclined road surface determined by the road surface inclination determination unit 11 in addition to the height H1 of the object based on the road surface below the vehicle. For example, when the vehicle is parked on a flat surface and the road surface behind it is also flat, the heights H1 and H2 of the objects are equal, but the vehicle is on a flat surface and the road surface behind it slopes up or down. , the heights H1 and H2 are different values. The object here is not limited to a three-dimensional object projecting from the road surface, but includes the road surface itself, and the height of the road surface according to the distance from the vehicle is calculated as the height of the object.

The tilt state determination unit 13 determines the tilt state of the road surface on which the vehicle is currently located from the tilt of the vehicle detected by the acceleration sensor 4 . That is, with respect to the relative inclination angle between the own vehicle and the road surface behind the own vehicle by the camera 2, the inclination angle of the own vehicle based on gravity is detected to determine whether the road surface on which the own vehicle is currently located is a sloped road. To determine the inclination state such as whether the road surface has steps or is flat.

The detection level adjustment unit 14 integrates the information from the road surface inclination determination unit 11, the height calculation unit 12, the inclination state determination unit 13, and the information from the accelerator opening sensor 5. 3 adjusts the detection level when detecting an obstacle. Specifically, the ultrasonic wave emitted from the ultrasonic sensor 3 receives the reflected wave reflected by the object, and the reflection intensity (the voltage value of the electromotive force generated in the sensor element by the reflected wave) equal to or greater than a predetermined threshold value When detecting the presence or absence of an object and its distance depending on whether or not it has a do.

For example, as shown in FIG. 2A, when the vehicle C moves backward from the sloping road surface K1 toward the flat road surface F1 and there is no three-dimensional object within the detection area R1 of the ultrasonic sensor 3 on the flat road surface F1, A reflected wave of the ultrasonic wave emitted from the ultrasonic sensor 3 reflected by the flat road surface F1 has a waveform as shown in FIG. 2(b) with respect to time t.

Therefore, if a threshold value TH is used with respect to the intensity (amplitude) W1 of the measured reflected wave on the assumption that the inclination of the vehicle does not change, depending on the inclination angle of the inclined road surface K1, the flat road surface in the detection area R1 The relative road surface height of F1 with the sloped road surface K1 as the reference plane becomes equal to or greater than the set value corresponding to the height of the bumper of the host vehicle, and the intensity W1 of the reflected wave exceeds the threshold value TH. There is a risk of erroneously detecting itself as an obstacle that may collide with the own vehicle.

For this reason, the detection level adjustment unit 14 adjusts the driving force output state based on the information from the inclination state determination unit 13 and the accelerator opening detected by the accelerator opening sensor 5 to change from a slope road or a road surface with steps to a flat road. movement, moving from a flat road to a sloping road or a road surface with a step, etc. Check if there is a three-dimensional object with a height of .

As for the movement state of the vehicle, for example, the inclination of the vehicle detected by the acceleration sensor 4 detects that the vehicle is on a slope, and the accelerator opening sensor 5 detects that the accelerator opening is smaller than a predetermined value. In this case, it can be determined that the vehicle is moving backward while going down a sloped road surface. Conversely, when it is detected that the vehicle is on a sloped road and the accelerator opening is greater than a predetermined value, it can be determined that the vehicle is moving backward while climbing the sloped road.

Based on the information from the road surface inclination determination unit 11 and the height calculation unit 12, the detection level adjustment unit 14 determines that there is no three-dimensional object higher than the height of the bumper within the detection area R1 of the ultrasonic sensor 3, and the detection area When the road surface height on R1 with the sloped road surface K1 of the flat road surface F1 as the reference plane is greater than or equal to the set value corresponding to the height of the bumper, as shown in FIG. A threshold value TH1 is set to be greater than the peak value of the intensity W1 of . As a result, it is possible to prevent the rear road surface from being erroneously detected as an obstacle when the vehicle moves backward from an inclined road surface toward a flat road surface.

Also, as shown in FIG. 3(a), when the vehicle C moves backward from the flat road surface F2 toward the sloping road surface K2 and there is no three-dimensional object within the detection area R2 of the ultrasonic sensor 3 on the sloping road surface K2. The same is true for That is, the detection level adjustment unit 14 determines that there is an uphill road surface behind the vehicle and a three-dimensional object higher than the bumper height based on the information from the inclination state determination unit 13 and the information from the accelerator opening sensor 5 . does not exist, and when it is determined that the road surface height with respect to the flat road surface F1 of the sloped road surface K2 in the detection area R2 is greater than or equal to the set value corresponding to the height of the bumper, as shown in FIG. , the threshold TH is adjusted to a threshold TH2 larger than the peak value of the intensity W2 of the reflected wave with respect to the intensity W2 of the reflected wave reflected on the inclined road surface K2, assuming that the inclination of the vehicle does not change. As a result, it is possible to prevent the rear road surface from being erroneously detected as an obstacle when the vehicle moves backward from a flat road surface toward an inclined road surface.

Furthermore, when there is a three-dimensional object projecting from the road surface behind the vehicle, the detection level is adjusted in consideration of the state of the road surface on which the three-dimensional object exists and the height of the three-dimensional object. For example, as shown in FIG. 4A, when the host vehicle C moves backward from a flat road surface F3 toward an uphill inclined road surface K3, the height of the three-dimensional object A projecting from the inclined road surface K3 from the inclined road surface K3 is Even if H3 is lower than the height of the rear bumper of the vehicle, the intensity W3 of the reflected wave from the three-dimensional object A in the detection area R3 of the ultrasonic sensor 3 increases before the vehicle starts climbing the slope K3. There is a possibility that the threshold TH may be exceeded, and there is a risk of erroneous detection as an obstacle that may collide with the own vehicle.

Therefore, as shown in FIG. 4B, the detection level adjustment unit 14 assumes that the inclination of the vehicle does not change with respect to the reflected wave W3 including the three-dimensional object A and reflected by the inclined road surface K3. The threshold TH thus obtained is adjusted to a threshold TH3 larger than the peak value of the intensity W3 of the measured reflected wave. That is, the threshold TH3 is set so as not to detect an object whose reflected wave intensity does not exceed (the height of the bumper) + (the height of the inclined road surface K3 from the flat road surface F2) when the vehicle is on the flat road surface F2. do. As a result, when the vehicle moves backward in a situation where the road surface behind the vehicle is sloping upward and a three-dimensional object that is lower than the height of the bumper protrudes from the inclined road surface, the three-dimensional object that is lower than the height of the bumper can be prevented from being erroneously detected as an obstacle.

The obstacle detection unit 15 checks the output voltage of the sensor element generated by the reflected wave of the ultrasonic wave emitted from the ultrasonic sensor 3, and the number of times the output voltage exceeds the threshold adjusted by the detection level adjustment unit 14 is a predetermined number of times. If it continues, it is detected as an obstacle that may collide with the own vehicle, and the distance to the obstacle is calculated from the time from transmission to reception of ultrasonic waves and the speed of sound. When the obstacle detection unit 15 detects an obstacle that may collide with the own vehicle, the obstacle detection unit 15 transmits detection information including distance data to an alarm device and a brake device (not shown) via the communication bus 100, Activate the brakes to prevent collisions with obstacles.

Next, processing related to obstacle detection by the obstacle detection device 1 will be described with reference to the flowchart shown in FIG.

In this obstacle detection process, first, in step S1, it is checked from the gear shift information of the vehicle received via the communication bus 100 whether or not the own vehicle is in the reverse running state. If the vehicle is not backing up, this process is exited, and if the vehicle is backing up, the process proceeds to step S2 to calculate the relative inclination angle of the road surface behind the vehicle from the image captured by the camera 2, and Calculate the presence and height of protruding three-dimensional objects.

Next, in step S3, the movement state of the own vehicle is determined from the processing result of step S2 and the accelerator opening detected by the accelerator opening sensor 5, and the obstacle detection level ( threshold). Then, proceeding from step S3 to step S4, it is checked whether or not the intensity (peak value) of the reflected wave is equal to or greater than the threshold.

In step S4, if the intensity of the reflected wave is less than the threshold, it is determined that there is no obstacle that may collide with the host vehicle, and this process is exited. If the peak value of the reflected wave is greater than the threshold, step S4 Proceeding from S4 to step S5, the corresponding object is detected as an obstacle, and the distance from the own vehicle to the obstacle is calculated. Then, detection information including distance data of the obstacle is transmitted to an alarm device and a braking device (not shown) via the communication bus 100, and alarms and brakes are activated to prevent collision with the obstacle.

As described above, in the present embodiment, when detecting an obstacle existing behind the own vehicle, from the captured image of the camera 2, the relative inclination angle of the road surface behind the own vehicle and the three-dimensional object protruding from the road surface are detected. In addition to determining the presence and height of the obstacle, the relationship with the road surface behind the vehicle is determined from the inclination angle of the vehicle measured by the acceleration sensor 4, and the detection level of the obstacle detection for the reflected wave of the ultrasonic sensor 3 is adjusted. . As a result, erroneous detection of obstacles caused by the slope of the road surface can be prevented, and erroneous alarms and erroneous brake operations can be avoided.

1 Obstacle Detection Device 2 Camera 3 Ultrasonic Sensor 4 Acceleration Sensor 5 Accelerator Opening Sensor 10 Controller 11 Road Inclination Determining Section 12 Height Calculating Section 13 Inclination State Determining Section 14 Detection Level Adjusting Section 15 Obstacle Detecting Section

Claims (3)

A vehicular obstacle detection device for receiving a reflected wave of an investigation wave emitted from the own vehicle and reflected by an object, and detecting an object whose reflection intensity exceeds a predetermined threshold as an obstacle,
a road surface inclination determining unit that processes an image captured by a camera of a traveling road surface on which the vehicle is traveling and determines a relative inclination state of the traveling road surface with respect to a reference plane fixed to the own vehicle;
a height calculation unit that calculates the height of an object on the traveling road surface;
a tilt state determination unit that detects the tilt of the vehicle with respect to the direction of gravity and determines the tilt state of the reference plane;
A movement state of the vehicle is discriminated from an inclination state of the reference plane and a driving force output state based on the accelerator opening of the vehicle, and the inclination state of the travel road surface and the travel road surface are determined according to the determined movement state. and a detection level adjustment unit that adjusts the detection level of the obstacle by varying the threshold based on the height of the object. The height calculation unit calculates a road surface height of the traveling road surface from the reference plane as the height of the object on the traveling road surface,
The detection level adjustment unit sets the threshold to a value exceeding the reflection intensity from the traveling road surface when the height of the traveling road surface from the reference plane in the detection area by the exploration wave is greater than or equal to a set value. The vehicle obstacle detection device according to claim 1, characterized by: The height calculation unit calculates the height of a three-dimensional object projecting from the travel road surface from the travel road surface as the height of the object on the travel road surface,
The detection level adjustment unit sets the threshold to a value exceeding the reflection intensity from the three-dimensional object when the height of the three-dimensional object from the traveling road surface in the detection area by the search wave is equal to or less than a set value. The vehicle obstacle detection device according to claim 1.

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