JP2019086402A - Obstacle detector for vehicles - Google Patents

Abstract

To prevent misdetection of an obstacle caused by the inclination of a road surface when detecting an obstacle present in the travel direction of the vehicle.SOLUTION: A road surface inclination determination unit 11 processes the image captured by a camera 2, estimates the relative angle of inclination of a road surface behind the vehicle relative to a reference plane fixed to the vehicle, and determines the inclination state of the backward road surface. A height calculation unit 12 recognizes an object present behind the vehicle from the captured image of the camera 2 and calculates the height of the object. An inclination state determination unit 13 determines the inclination state of a road surface where the vehicle is currently located from the inclination of the vehicle detected by an acceleration sensor 4. Then, in a detection level adjustment unit 14, information from the road surface inclination determination unit 11, the height calculation unit 12 and the inclination state determination unit 13 are integrated, a detection level when detecting an obstacle by an ultrasonic sensor 3 is adjusted by an obstacle detection unit 15, and misdetection of an obstacle caused by the inclination of a road surface is thereby prevented.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle obstacle detection device for detecting an obstacle present in the traveling direction of a vehicle.

  In a vehicle such as a car, a device or system is known that outputs an exploration wave such as an ultrasonic wave or a millimeter wave toward an object, and detects an obstacle by examining a reflection wave reflected by the exploration wave. It is.

  For example, in Patent Document 1, when an ultrasonic sensor is used to detect the distance between an obstacle and a vehicle present in the traveling direction of the vehicle, and the distance between the obstacle and the vehicle becomes less than a predetermined threshold, obstacle A vehicle periphery monitoring system is disclosed that notifies a driver of the presence of an object or operates a brake to avoid a collision with an obstacle.

JP, 2015-135301, A

  However, when the attitude of the vehicle changes due to the slope of the road, such as when moving backward from a flat road surface to an inclined road surface or when moving backward from an inclined road surface to a flat road surface, the car stops or the road surface itself Although there is no risk of contact or collision with the vehicle, it may be erroneously detected as an obstacle contacting or colliding with the host vehicle, which may result in false alarm or erroneous operation of the brake.

  The present invention has been made in view of the above circumstances, and when detecting an obstacle present in the traveling direction of the host vehicle, an obstacle for a vehicle capable of preventing erroneous detection of the obstacle due to the inclination of the road surface. The purpose is to provide a detection device.

  The obstacle detection device for a vehicle according to one aspect of the present invention receives a reflection wave in which a search wave emitted from a host vehicle is reflected by an object, and an object whose reflection intensity exceeds a predetermined threshold is an obstacle. An obstacle detection device for detecting an inclination of the road surface on which the vehicle travels with respect to a reference plane fixed to the vehicle and a height of the object on the road surface; The height calculation unit to be calculated, the inclination state determination unit that detects the inclination of the host vehicle relative to the gravity direction, and determines the inclination state of the reference plane, the inclination state of the traveling road, and the height of the object on the traveling road And a detection level adjustment unit that adjusts the detection level of the obstacle by changing the threshold value based on the inclination of the reference plane and the reference plane.

  According to the present invention, when detecting an obstacle present in the traveling direction of the host vehicle, it is possible to prevent erroneous detection of the obstacle caused by the inclination of the road surface.

Block diagram of obstacle detection device for vehicles An explanatory view showing adjustment of an obstacle detection level at the time of a vehicle retreating from a slope road surface to a flat road surface An explanatory view showing adjustment of an obstacle detection level at the time of a vehicle retreating from a flat road surface to a slope road surface Explanatory drawing showing adjustment of the obstacle detection level in case a solid object exists on a slope road surface Flow chart of obstacle detection process

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes an obstacle detection device for a vehicle mounted on a vehicle such as a car and emitting a search wave in the traveling direction of the vehicle to detect an obstacle (hereinafter simply referred to as “obstacle detection device” ). In the present embodiment, the obstacle detection device 1 uses ultrasonic waves as a search wave for detecting an obstacle, and the camera 2 and the ultrasonic sensor 3 installed at the rear of the vehicle A situation and an obstacle are detected, and further, information from the acceleration sensor 4 and the accelerator opening degree sensor 5 is added to detect an external environment at the time of backward movement of the vehicle and a state of the own vehicle.

  In addition, although the ultrasonic sensor 3 is represented and demonstrated by one sensor in the following, it is also the same as in the case where a some sensor is provided. Also, as a sensor for emitting a probe wave for detecting an obstacle, a millimeter wave radar or a lidar (Light Detection and Ranging) may be used instead of the ultrasonic sensor 3. Furthermore, the camera 2 may be replaced by a millimeter wave radar or a rider.

  The obstacle detection device 1 includes a controller 10 as a control unit that processes information from the camera 2, the ultrasonic sensor 3, the acceleration sensor 4, and the accelerator opening sensor 5. The controller 10 is configured around 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 cause a collision in the vehicle body at the time of backward movement of the vehicle, the controller 10 transmits information on the obstacle to a warning device or a braking device (not shown) via the communication bus 100 And brakes to avoid collision with obstacles.

  At this time, the controller 10 determines the inclination of the road surface behind the host vehicle and the height of the object from the captured image of the camera 2 to adjust the detection level of the ultrasonic sensor 3 and disturbs the object exceeding the adjusted detection level. By detecting the object as an object, it is possible to prevent a false alarm or an erroneous operation of the brake for an object without a risk of collision. Therefore, the controller 10 includes a road surface inclination determination unit 11, a height calculation unit 12, an inclination state determination unit 13, a detection level adjustment unit 14, and an obstacle detection unit 15 as functional units related to obstacle detection.

  The road surface inclination determination unit 11 processes the image captured by the camera 2 to estimate the relative inclination angle of the road surface behind the host vehicle with respect to the reference plane fixed to the host vehicle, and determines the inclination state of the road surface behind Do. For example, in the case of adopting a stereo camera that arranges two cameras at predetermined intervals and images the same object from different viewpoints as the camera 2, multiple feature points are extracted from the captured image, and the parallax of each feature point is extracted. From this, coordinate values in a three-dimensional space of the feature points fixed to the vehicle are determined according to the principle of triangulation, and a plane equation approximating the road surface is calculated using statistical processing such as least squares method or Hough transform. Then, the inclination angle of the plane represented by the plane formula is taken as the inclination angle relative to the road surface behind the host vehicle with respect to the reference plane assuming the flat road surface under the host vehicle.

  The height calculation unit 12 recognizes an object present behind the host vehicle from the captured image of the camera 2 and calculates the height of the object. For example, when a stereo camera is adopted as the camera 2, a flat road surface in the lower part of the vehicle is used as a reference plane, and feature points projecting from the reference plane are extracted. Then, the extracted feature points are grouped to recognize a three-dimensional object, and the protruding height H1 of the recognized three-dimensional object from the reference plane is calculated as the height of the object.

  In addition to the height H1 of the object relative to the road surface below the own vehicle, the height calculation unit 12 also calculates the height H2 of the object on the inclined road surface determined by the road surface inclination determination unit 11. For example, in the case where the own vehicle is stopped on a flat ground and the road surface on the rear is the same flat ground, the heights H1 and H2 of the objects are equal, but the ground road on the rear is uphill or downhill The heights H1 and H2 have different values in the case of the inclined surface of The object here is not limited to a three-dimensional object protruding from the road surface, and includes the road surface itself, and the road surface height according to the distance from the host vehicle is calculated as the height of the object.

  From the inclination of the host vehicle detected by the acceleration sensor 4, the inclination state determination unit 13 determines the inclination state of the road surface on which the host vehicle is currently located. 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, and Whether the road surface is uneven or uneven is determined.

  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 degree sensor 5 to obtain an ultrasonic sensor by the obstacle detection unit 15. Adjust the detection level when detecting an obstacle by 3. Specifically, the ultrasonic wave emitted from the ultrasonic sensor 3 receives the reflection wave reflected by the object, and the reflection intensity above the predetermined threshold (voltage value of electromotive force generated in the sensor element by the reflection wave) When detecting the presence or absence and distance of an object, adjust the detection level of the obstacle by changing the threshold according to the inclination of the vehicle, the road slope behind, and the height of the object on the road Do.

  For example, as shown in FIG. 2A, when the host vehicle C retreats from the inclined road surface K1 toward the flat road surface F1 and there is no three-dimensional object in the detection area R1 of the ultrasonic sensor 3 on the flat road surface F1: The reflected wave in which the ultrasonic wave emitted from the ultrasonic sensor 3 is reflected by the flat road surface F1 has a waveform as shown in FIG. 2B with respect to time t.

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

  For this reason, the detection level adjustment unit 14 changes the road surface having a graded road or a step from a road surface having a level difference to a flat road according to the information from the inclination state determination unit 13 and the output state of the driving force based on the opening degree detected by the accelerator opening degree sensor 5 Determines the movement state of the vehicle when moving backward, such as movement from a flat road to a slope road or a road surface with steps, and the information from the height calculation unit 12 determines the rear bumper of the vehicle. Check if there is a three-dimensional object above the height of.

  The moving state of the host vehicle is detected, for example, from the inclination of the host vehicle detected by the acceleration sensor 4 that the host vehicle is on the slope road, 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 slope road surface. On the contrary, it is detected that the host vehicle is on the slope road, and when the accelerator opening degree is larger than the predetermined value, it can be determined that the vehicle is moving backward while climbing the slope road surface.

  Then, according to the information from the road surface inclination determination unit 11 and the height calculation unit 12, the detection level adjustment unit 14 does not have a three-dimensional object greater than the height of the bumper in the detection area R1 of the ultrasonic sensor 3. When the height of the road surface with reference to the inclined road surface K1 of the flat road surface F1 in R1 is equal to or greater than the set value corresponding to the height of the bumper, as shown in FIG. The threshold value TH1 is larger than the peak value of the intensity W1. This makes it possible to prevent the rear road surface from being erroneously detected as an obstacle when the host vehicle moves backward from the inclined road surface toward the flat road surface.

  Further, as shown in FIG. 3A, when the host vehicle C retreats from the flat road surface F2 toward the inclined road surface K2 and there is no three-dimensional object in the detection area R2 of the ultrasonic sensor 3 on the inclined road surface K2. The same is true. That is, based on the information from the inclination state determination unit 13 and the information from the accelerator opening degree sensor 5, the detection level adjustment unit 14 has a road surface of a rising slope behind the host vehicle, When it is determined that the road surface height with the flat road surface F1 of the inclined road surface K2 in the detection area R2 as the reference plane is equal to or greater than the set value corresponding to the height of the bumper, as shown in FIG. With respect to the intensity W2 of the reflected wave reflected by the inclined road surface K2, the threshold TH on the premise that the inclination of the host vehicle does not change is adjusted to a threshold TH2 larger than the peak value of the intensity W2 of the reflected wave. This makes it possible to prevent the rear road surface from being erroneously detected as an obstacle when the host vehicle moves backward from a flat road surface toward an inclined road surface.

  Furthermore, the same applies to the case where a three-dimensional object protruding from the road surface is present behind the host vehicle, and the detection level is adjusted in consideration of the state of the road surface where 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 the flat road surface F3 toward the uphill slope road surface K3, the height from the slope road surface K3 of the three-dimensional object A protruding from the slope road surface K3 Even if H3 is lower than the height of the rear bumper of the vehicle, the intensity W3 of the reflected wave from the solid object A in the detection area R3 of the ultrasonic sensor 3 is before the vehicle starts to climb the inclined road surface K3. There is a possibility that the threshold TH is exceeded, and there is a possibility that the obstacle may be erroneously detected as an obstacle which may cause a collision with the host 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 reflected by the inclined road surface K3 including the three-dimensional object A. The threshold TH is adjusted to a threshold TH3 larger than the peak value of the measured intensity W3 of the reflected wave. That is, when the vehicle is on the flat road surface F2, the threshold TH3 is set so as not to detect an object that does not exceed the reflected wave intensity of (the height of the bumper) + (the height of the inclined road surface K3 from the flat road F2). Do. As a result, when the road surface behind the host vehicle is inclined upward, and the host vehicle retreats in a situation where a solid object lower than the height of the bumper protrudes from the inclined road surface, the solid object lower than the height of the bumper Can be prevented from being falsely detected as an obstacle.

  The obstacle detection unit 15 examines 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 becomes equal to or higher than the threshold adjusted by the detection level adjustment unit 14 is a predetermined number of times When continuing, while detecting as an obstacle which has a possibility of a collision with a self-vehicle, time from transmission of ultrasonic waves to reception and distance from an acoustic velocity are calculated. Then, when the obstacle detection unit 15 detects an obstacle that may cause a collision in the own vehicle, the obstacle detection unit 15 transmits detection information including distance data to an alarm device or a brake device (not shown) via the communication bus 100, Activate the brake to prevent a collision with an obstacle.

  Next, processing relating to obstacle detection of the obstacle detection device 1 will be described using the flowchart shown in FIG.

  In the obstacle detection process, first, in the first step S1, it is checked from the shift information of the vehicle received via the communication bus 100 whether or not the host vehicle is in the backward traveling state. Then, if the vehicle is not set back, the process is skipped, and if the vehicle is set back, the process proceeds to step S2 to calculate the relative inclination angle of the road surface behind the host vehicle from the captured image of the camera 2 Calculate the presence / absence and height of the protruding three-dimensional object.

  Next, the process proceeds to step S3, the movement state of the vehicle is determined from the processing result in step S2 and the accelerator opening detected by the accelerator opening sensor 5, and the detection level of obstacle detection for the reflected wave of the ultrasonic sensor 3 ( Adjust the threshold). Then, the process proceeds from step S3 to step S4, and it is checked whether the intensity (peak value) of the reflected wave is equal to or higher than a threshold.

  In step S4, if the intensity of the reflected wave is less than the threshold, it is judged that there is no obstacle that may collide with the host vehicle, and the process is exited, and if the peak value of the reflected wave is equal to or more than the threshold, the step From step S4 to step S5, a corresponding object is detected as an obstacle, and the distance from the host vehicle to the obstacle is calculated. Then, detection information including distance data of the obstacle is transmitted to an alarm device or a brake device (not shown) via the communication bus 100, and an alarm or a brake is operated to prevent a collision with the obstacle.

  As described above, in the present embodiment, when detecting an obstacle present behind the host vehicle, the relative inclination angle of the road surface behind the host vehicle from the captured image of the camera 2 and the three-dimensional object protruding from the road surface To determine the relationship between the inclination angle of the vehicle measured by the acceleration sensor 4 and the road surface behind it, and adjust the detection level of obstacle detection for the reflected wave of the ultrasonic sensor 3 . As a result, it is possible to prevent an erroneous detection of an obstacle caused by the inclination of the road surface, and to avoid an erroneous alarm or an erroneous operation of the brake.

DESCRIPTION OF SYMBOLS 1 obstacle detection apparatus 2 camera 3 ultrasonic sensor 4 acceleration sensor 5 accelerator opening degree sensor 10 controller 11 road surface inclination determination part 12 height calculation part 13 inclination state determination part 14 detection level adjustment part 15 obstacle detection part

Claims (4)

An obstacle detection device that receives a reflected wave in which a survey wave emitted from a host vehicle is reflected by an object and detects an object whose reflection intensity exceeds a predetermined threshold as an obstacle.
A road surface inclination determination unit that determines an inclination state of a traveling road surface on which the vehicle travels with respect to a reference plane fixed to the vehicle;
A height calculation unit that calculates the height of the object on the traveling road surface;
An inclination state determination unit that detects the inclination of the host vehicle with respect to the gravity direction and determines the inclination state of the reference plane;
A detection level adjustment unit that adjusts the detection level of the obstacle by varying the threshold value based on the inclination state of the traveling road surface, the height of the object on the traveling road surface, and the inclination state of the reference plane. Obstacle detection device characterized by.   The obstacle detection device according to claim 1, wherein the road surface inclination determination unit calculates an inclination angle of the traveling road surface relative to the reference plane from the image of the traveling road surface captured by a camera. The height calculation unit calculates, as the height of the object on the traveling road surface, the road surface height from the reference plane of 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 road surface height from the reference plane of the traveling road surface in the detection area by the search wave is equal to or greater than a set value. The obstacle detection device according to claim 1 or 2, characterized by The height calculation unit calculates, as the height of the object on the traveling road surface, the height from the traveling road surface of the three-dimensional object protruding from the traveling road surface,
The detection level adjustment unit may set the threshold to a value exceeding the reflection intensity from the three-dimensional object when the height from the traveling road surface of the three-dimensional object in the detection area by the exploration wave is equal to or less than a set value. The obstacle detection device according to claim 1 or 2, characterized in that:

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