JP2022168474A - Onboard radar device - Google Patents

Abstract

To provide an onboard radar device which can efficiently detect the adherence of snow to a receive device.SOLUTION: An onboard radar device 1 comprises: a transmit device 10 for transmitting a radio wave toward the surrounding of a vehicle V; a receive device 20 for receiving a reflected wave of the transmitted radio wave; and a control device 30 for detecting an object existing in the surrounding of the vehicle V on the basis of the received reflected wave. The control device 30 is constituted so as to execute a snow adherence assessment process of assessing whether or not snow adheres to the receive device on the basis of the reflected wave. The control device 30 is constituted so as to exercise the snow adherence assessment process in only a range Z, of the entire range in which the object is detectable, that is preliminarily defined as a range Z where detection of the object is difficult due to the fact that the snow flung up during the travel of the vehicle adheres to a portion of the receive unit 20.SELECTED DRAWING: Figure 4

Description

The present invention relates to an in-vehicle radar device that is mounted in a vehicle and that recognizes (detects) objects existing around the vehicle.

Conventionally, an in-vehicle radar device (hereinafter referred to as "conventional device") that is mounted on a vehicle and recognizes objects existing around the vehicle is known (see, for example, Patent Document 1 below). A conventional device includes a transmitter, a receiver, a controller, and the like. Further, the conventional device includes a case (housing) that accommodates the transmitting device, the receiving device, the control device, and the like. The transmitting device transmits radio waves toward the surroundings of the vehicle (for example, obliquely to the rear). The radio waves are reflected by objects (vehicles, passers-by, road surfaces, etc.) located around the vehicle. The receiving device includes a receiving antenna that receives the reflected wave and outputs a signal representing the reflected wave (hereinafter referred to as "reflected wave signal"). Based on the reflected wave signal, the control device calculates the positions (distance from the vehicle, direction viewed from the vehicle, etc.) of multiple (several hundred) reflection points (reflection points of the transmitted radio wave), and performs the calculation. Based on the results, objects existing around the vehicle are recognized.

Conventional devices are attached, for example, to the corners of bumper covers of vehicles. Compared to the case where the corner of the bumper cover where the receiving antenna is attached (hereinafter referred to simply as "receiving antenna" or "receiving device") is exposed If there is snow on the receiving antenna (if the receiving antenna is partly covered with snow), the receiving antenna cannot easily receive the reflected wave. As a result, the object recognition accuracy (accuracy) of the conventional apparatus is lowered. Therefore, the conventional device has a function of determining "whether or not snow adheres to the receiving antenna". In the following description, the process of determining "whether or not snow adheres to the receiving antenna" is referred to as "snow adhesion determination process".

JP-A-2000-019242

For example, in the conventional device, based on the average value of the positions of all reflection points (reflection points located within the entire detection range (hereinafter referred to as the “field of view”) of the conventional device), "snow on the receiving antenna It is possible to adopt a method of determining whether or not there is adhesion. This determination method is hereinafter referred to as the first method. On the other hand, for example, in the conventional device, the field of view is divided into a plurality of regions, and the average value of the positions of the reflection points is calculated for each region. It is also possible to adopt a method of determining whether or not This determination method is hereinafter referred to as the second method.

By the way, there is a case where snow adheres to a part of the receiving antenna and does not adhere to other parts. In this state, when the first method is adopted, the reflection points located within the field of view of the portion where snow is not attached may have a large effect on the average value. In this case, it may be determined that "snow does not adhere to the receiving antenna". On the other hand, when the second method is adopted, the calculation amount of the arithmetic unit (the number of determinations per predetermined time) is larger than when the first method is adopted. That is, the computational load increases.

One of the objects of the present invention is to provide an in-vehicle radar device capable of efficiently detecting adhesion of snow to a receiving device.

In order to solve the above problems, the in-vehicle radar device (1) of the present invention comprises:
a transmitting device (10) for transmitting radio waves toward the surroundings of the vehicle;
a receiving device (20) for receiving reflected waves of the transmitted radio waves;
a control device (30) for detecting an object existing around the vehicle based on the received reflected wave;
Prepare.
The control device is configured to execute snow adhesion determination processing for determining whether or not snow adheres to the reception device based on the reflected wave.
The control device is
A range defined in advance as a range in which detection of the object becomes difficult due to adhesion of snow picked up while the vehicle is running to a part of the receiving device, out of the entire range (Va) in which the object can be detected. It is configured such that only (Z) is subjected to the snow adhesion determination process.

As described above, in the in-vehicle radar device according to the present invention, the range in which it becomes difficult to detect an object when snow adheres to the receiving device while the vehicle is running is defined in advance, out of the total detection range (field of view). Then, the control device treats only that range as the target of the snow adhesion determination process. Therefore, it is possible to improve the determination accuracy (accuracy) of whether or not snow adheres to the receiving unit, as compared with the case of adopting the first method described above. Furthermore, since the amount of calculation is less than when the above-described second method is adopted, the calculation load of the control device can be reduced. Thus, according to the present invention, it is possible to efficiently determine snow adhesion to the receiving device.

FIG. 1 is a perspective view showing the rear part of a vehicle to which an in-vehicle radar device 1 according to one embodiment of the invention is applied. FIG. 2 is a block diagram of the vehicle-mounted radar device 1 shown in FIG. FIG. 3A is an enlarged plan view of the right rear portion of the vehicle. FIG. 3B is an enlarged perspective view of the right rear portion of the vehicle. FIG. 4 is a flow chart of the snow adhesion determination program.

(Constitution)
As shown in FIG. 1, an in-vehicle radar device 1 according to an embodiment of the present invention is provided, for example, at corners (left and right ends) of a rear bumper cover of a vehicle V, and is mounted on the rear and side of the vehicle. Recognize objects in the direction. As will be described later in detail, the vehicle-mounted radar device 1 has a function of determining whether or not snow adheres to the surface of the receiving antenna 21 .

The in-vehicle radar device 1 includes a transmitting device 10, a receiving device 20, and a control device 30, as shown in FIG. 2, like conventional devices.

Transmitting device 10 includes transmitter 11 and transmitting antenna 12 . The transmitter 11 includes a signal source 11a that outputs a signal of constant frequency (for example, a sine wave) and a modulator 11b that changes the frequency of the signal output from the signal source 11a at a predetermined cycle. The transmitting antenna 12 transmits the signal (modulated signal) output from the modulating device 11b obliquely rearward from the vehicle V. As shown in FIG.

The receiving device 20 includes a receiving antenna 21 and an amplifying device 22 . The receiving antenna 21 is provided at the corner of the rear bumper cover of the vehicle V. As shown in FIG. As shown in FIG. 3A, in a plan view of the vehicle V, the central axis C of the receiving antenna 21 is oriented obliquely rearward. It includes a plurality of antenna elements 21a. The receiving antenna 21 is composed of a plurality of antenna elements 21a, 21b, . Each of the antenna elements 21a, 21b, . RSb, . . . are respectively output. Each of the antenna elements 21a, 21b, . Each antenna element 21a, 21b, . . . is oriented in a different direction. This realizes a wide FOV (=Field Of View). That is, although the detection range (receiving range) of each antenna element 21a, 21b, . . . By arranging the plurality of antenna elements 21a, 21b, . 3A, the detection range of 1 (hereinafter referred to as "field of view") is "±75°" centered on the central axis C. Here, with respect to the central axis C, the vehicle The front side is defined as the "+" side, and the rear side of the vehicle is defined as the "-" side.The above detection range is an example, and it may be slightly wider or narrower than this example. good.

Referring to FIG. 2 again, the amplifier 22 amplifies the reflected wave signal output from each antenna element 21 a and supplies the amplified signal to the controller 30 .

The control device 30 includes an arithmetic device 31 (hereinafter referred to as "CPU"), a storage device 32 (RAM, ROM, etc.), a communication device 33, and the like. The CPU executes computer programs pre-stored in the storage device 32 . The CPU is connected to the communication network CAN via the communication device 33 . A control device (main ECU) of the vehicle V (not shown) is also connected to the communication network CAN, and information about objects existing around the vehicle V can be transmitted and received between the CPU and the main ECU.

(motion)
When the vehicle V is started (the engine is started), the CPU executes an object detection program (not shown) at a predetermined cycle, and sequentially acquires the reflected wave signals RSa, RSb, . , and analyze them to recognize objects existing around the vehicle V (particularly obliquely behind). The CPU then transmits the recognition result to the main ECU via the communication device 33 . However, the CPU executes the object detection program when the object detection permission flag F, which will be described later, is "1", and does not execute the object detection program when the object detection permission flag F is "0".

By the way, when the vehicle V runs in the snow, the rear wheels of the vehicle V roll up the snow to the rear of the vehicle V. As shown in FIG. Since the air behind the vehicle V has a negative pressure, the snow that has been rolled up as described above adheres to the rear surface of the vehicle V. As shown in FIG. That is, mainly the region X extending from the vicinity of the center axis C of the receiving antenna 21 to the rear half side is covered with snow (see FIG. 3B). As a result, the field of view of the in-vehicle radar device 1 becomes narrower than in normal times. When the receiving antenna 21 (the corner of the rear bumper cover) is completely exposed, the field of view Va of the vehicle-mounted radar device 1 is "-75°" to "+75°" as described above (Fig. 3A ). On the other hand, when the area X of the receiving antenna 21 (the corner of the rear bumper cover) is covered with snow, the field of view Vb of the vehicle-mounted radar device 1 is about "-5°" to "+75°". . That is, when the vehicle V travels in the snow, the vehicle-mounted radar device 1 detects an object located within a range Z (“−75°” to “−5°” (invisible range)) of the field of view Va excluding the field of view Vb. difficult to recognize. The range Z is measured (or calculated) in advance, and data representing the range Z is stored in the storage device 32 . It should be noted that the numerical value of the range Z described above is an example, and the numerical value may vary depending on the vehicle type.

As described above, in principle, the CPU periodically executes the object detection program, but executes the snow adhesion determination program shown in FIG. 4 during periods when the object detection program is not executed. That is, the CPU alternately executes the object detection program and the snow adhesion determination program.

The CPU starts the snow adhesion determination program from step 400 . Next, at step 401 , the CPU controls the transmitting device 10 to transmit radio waves from the transmitting antenna 12 . The CPU temporarily stops the transmission of radio waves when a predetermined short time Δt elapses after starting the transmission of radio waves.

Next, in step 402, the CPU acquires the reflected wave signals RSa, RSb, . Compute the position of a point.

Next, at step 403, the CPU selects, from among the plurality of reflection points, reflection points included in the range Z preset as described above.

Next, in step 404, the CPU executes snow adhesion determination processing as follows. Here, if the area X is not covered with snow, the reflected wave from the ground is incident on the area X. That is, in this case, the multiple reflection points are uniformly distributed in the lower part of the range Z, and the distance between the center O of the receiving antenna 21 and each reflection point is relatively long. On the other hand, when the area X is covered with snow, a plurality of reflection points are distributed over substantially the entire range Z, and the distance between the center O and the reflection points is very short. Therefore, based on the distribution shape of the selected reflection points, the distance between the center O and the reflection points, and the like, the CPU determines whether or not the area X of the receiving antenna 21 is covered with snow (the area X is covered with snow). (whether or not)” is determined. For example, when the average nearest distance of the plurality of selected reflection points is greater than a predetermined value D and the average value of the distances between the center O and each reflection point is equal to or less than a predetermined short distance Δd, the CPU 21 is covered with snow (area X is covered with snow)", and the process proceeds to step 405.

Next, at step 405, the CPU sets the object detection permission flag F to "0". After that, the CPU does not execute the object detection program until the object detection permission flag F is reset to "1". That is, execution of object detection processing is prohibited.

Next, in step 406, the CPU receives information indicating that "an object around the vehicle V cannot be detected because the receiving antenna 21 is covered with snow (area X is covered with snow)". is transmitted to the main ECU via the communication device 33 . The main ECU controls, for example, an audio device, a video display device, and the like to present the same information (sound, image, etc.) to the driver.

Then, at step 407, the CPU terminates the snow adhesion determination program.

On the other hand, in step 404, for example, when the average nearest distance is equal to or less than a predetermined value D, or when the average value of the distances between the center O and each reflection point is greater than a predetermined short distance Δd, the CPU selects the "receiving antenna 21 area X is not covered with snow (area X is not covered with snow)", and the process proceeds to step 408.

Next, at step 408, the CPU sets the object detection permission flag F to "1". That is, execution of object detection processing is permitted. Next, in step 409, the CPU transmits to the main ECU via the communication device 33 information indicating that "objects around the vehicle V can be detected." The main ECU controls, for example, an audio device, a video display device, and the like to present the same information (sound, image, etc.) to the driver. Then, the CPU proceeds to step 407 and terminates the snow adhesion determination program.

Note that the CPU periodically executes the snow adhesion determination program even in a state in which execution of the object detection program is prohibited (a state in which the object detection permission flag F is "0").

(effect)
As described above, in the in-vehicle radar device 1, the range Z within the field of view Va is defined in advance in which it becomes difficult to detect an object when snow adheres to the receiving antenna 21 (the corner of the rear bumper cover) while driving. . Then, the CPU targets only the range Z for the snow adhesion determination process. Therefore, it is possible to improve the determination accuracy (accuracy) of whether or not snow adheres to the receiving antenna 21, as compared with the case where the first method described above is employed. Furthermore, since the field of view Vb is not subject to snow adhesion determination processing, the amount of calculation is less than in the case of adopting the above-described second method, so the computation load on the CPU can be reduced. Thus, according to the present embodiment, it is possible to efficiently determine whether or not snow has adhered to the reception antenna 21 (the corner of the rear bumper cover).

The present invention is not limited to the above embodiments, and various modifications can be adopted within the scope of the present invention as described below.

<Modification 1>
For example, in the above embodiment, snow adhesion to the receiving antenna 21 is judged based on the distribution of reflection points in the range Z and the distance from the center O in step 404 of the snow adhesion judgment program. Other techniques may be employed instead of or in addition to this technique. For example, based on the frequency characteristics (pattern) of the reflected wave, it may be determined whether snow has adhered to the receiving antenna 21 .

<Modification 2>
The above embodiment is an example in which the present invention is applied to the on-vehicle radar device 1 mounted on the rear portion of the vehicle V, but the present invention can also be applied to the on-vehicle radar device 1 mounted on other parts of the vehicle. is.

DESCRIPTION OF SYMBOLS 1... Vehicle-mounted radar apparatus, 10... Transmission apparatus, 11... Transmitter, 12... Transmission antenna, 20... Reception apparatus, 21... Reception antenna, 22... Amplifier, 30... Control apparatus, C... Central axis, F... Object detection permission flag, RSa, RSb...reflected wave signal, V...vehicle

Claims (1)

a transmitting device that transmits radio waves toward the surroundings of the vehicle;
a receiving device for receiving reflected waves of the transmitted radio waves;
a control device that detects an object existing around the vehicle based on the received reflected wave;
with
The control device is configured to execute a snow adhesion determination process for determining whether or not snow adheres to the receiving device based on the reflected wave.
An in-vehicle radar device,
The control device is
Among the entire range in which the object can be detected, only a range defined in advance as a range in which the detection of the object becomes difficult due to adhesion of snow picked up while the vehicle is running to a part of the receiving device. Configured to be subject to snow adhesion determination processing,
In-vehicle radar equipment.

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