JP2017211256A - Radar device and road side snow wall detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radar device with which it is possible to estimate the presence of a roadside snow wall even when a roadside object is buried in snow and estimate a road condition ahead the own vehicle.SOLUTION: The radar device comprises: a transmission/reception unit (11) for transmitting a radio wave as a transmitted signal to the front and receiving a reflected signal from a reflection object; a frequency analysis unit (12) for performing the frequency analysis of a beat signal between the transmitted signal and the reflected signal; a roadside snow wall candidate determination unit (14) for calculating the number of contiguous bins having signal strength greater than or equal to a first threshold among spectrum signals obtained from the analysis result and, when the number of contiguous bins is greater than or equal to determination bin counts, determining that a roadside snow wall candidate exists; a standard deviation calculation unit (15) for calculating the standard deviation of signal strength of each bin included in the number of contiguous bins; and a roadside snow wall determination unit (16) for determining that the roadside snow wall candidate is a roadside snow wall when the standard deviation is less than or equal to a determination standard deviation value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radar apparatus, and more particularly to a radar apparatus and a roadside snow wall detection method that are mounted on a vehicle and detect a road shape ahead of the host vehicle.

  Irradiate the surrounding area of the vehicle, receive the reflected signal from the target object, detect the object in front of the vehicle from the received signal, extract stationary object information from the detected object, and extract the stationary A radar device that estimates a road shape based on object information is known as a prior art (see, for example, Patent Document 1).

Japanese Patent No. 4637690

However, the prior art has the following problems.
In the case of Patent Document 1, the position of a stationary object on the road side is detected, and the road shape is estimated based on the position information.

  However, when there is a snow wall on the roadside, a stationary object or the like on the roadside object is buried in the snow. Therefore, the roadside stationary object is not detected due to the influence of the snow wall. For this reason, in the prior art like patent document 1, the number of roadside objects and position information required in order to estimate a road shape cannot be obtained, but there exists a subject that a road shape cannot be estimated.

  The present invention has been made to solve the above-described problems. Even when a roadside object such as a card rail, a tree, or a sign post is buried in snow, the presence or absence of a roadside snow wall is determined. An object of the present invention is to obtain a radar apparatus and a roadside snow wall detection method that can estimate the road shape ahead of the host vehicle.

  A radar apparatus according to the present invention is mounted on a vehicle, transmits a radio wave as a transmission signal to the front of the host vehicle, and receives a radio wave reflected by a transmission signal from a reflector in front of the host vehicle as a reflection signal; A frequency analysis unit that performs frequency analysis on the beat signal of the transmission signal and the reflection signal, and bins having a signal intensity equal to or higher than a predetermined first threshold among the spectrum signals obtained from the analysis result of the frequency analysis unit. When the number of continuous bins is equal to or greater than the predetermined number of determination bins, a roadside snow wall candidate determination unit that determines that a roadside snowwall candidate exists in the reflector, When the roadside snow wall candidate determination unit determines that there is a roadside snowwall candidate, a standard deviation calculation unit that calculates a standard deviation of the signal strength of each bin included in the continuous bin number, and a standard deviation calculation If determined following standard deviation standard deviation in the calculated is predetermined, roadside Yukikabe candidate is one that includes a a determining roadside Yukikabe determination unit is roadside Yukikabe.

  The roadside snow wall detection method according to the present invention is a roadside snow wall detection method executed in the radar apparatus of the present invention, wherein a transmission signal that is a radio wave transmitted in front of the host vehicle and the transmission signal is the host vehicle. The first step of analyzing the frequency of the beat signal with the reflected signal obtained by reflecting with the reflector existing in front of the signal, and the spectrum signal obtained from the frequency analysis result of the first step is predetermined. In the second step of calculating the number of consecutive bins having a signal intensity equal to or higher than the first threshold as the number of consecutive bins, and when the number of consecutive bins is equal to or greater than a predetermined number of determination bins, The third step for determining that there is a roadside snow wall candidate, and if it is determined in the third step that there is a roadside snowwall candidate, the standard of the signal strength of each bin included in the continuous bin number A fourth step for calculating the difference, and a fifth step for determining that the road-side snow wall candidate is a road-side snow wall if the standard deviation calculated in the fourth step is equal to or less than a predetermined determination standard deviation value. Is.

  According to the present invention, even when a general roadside object is buried in a snow wall and cannot be detected by a radar device, it is possible to determine the presence or absence of a snow wall by performing signal processing based on reflection information from the snow wall. In addition, it has a configuration that makes it possible to detect the shape of the road ahead of the host vehicle by a simple method using the information on the snow wall. As a result, even when a roadside object such as a card rail, a tree, or a sign post is buried in snow, the presence or absence of a roadside snow wall can be determined, and the road shape ahead of the host vehicle can be estimated. A radar device and a roadside snow wall detection method can be obtained.

1 is a structural diagram of a radar apparatus according to Embodiment 1 of the present invention. It is the flowchart which showed the series of processes performed by the radar apparatus in Embodiment 1 of this invention. In Embodiment 1 of this invention, it is the figure which showed the frequency-analysis result in the frequency-analysis part as a frequency bin and the vertical axis | shaft as the signal strength of the reflected signal. In Embodiment 1 of this invention, when the own vehicle is drive | working the side of a snow wall, it is explanatory drawing which showed the case where several other vehicles exist ahead. In Embodiment 1 of this invention, it is the figure which showed the result of having performed the distance correction | amendment by step S104 in the state of FIG. 4 as a frequency bin and the vertical axis | shaft as the signal strength of the reflected signal. In Embodiment 1 of this invention, when the own vehicle is driving the side of a snow wall, it is explanatory drawing which showed the case where there are few other vehicles ahead. In Embodiment 1 of this invention, it is the figure which showed the result of having performed the distance correction | amendment by step S104 in the state of FIG. 6 as a frequency bin and the vertical axis | shaft as the signal strength of the reflected signal. In Embodiment 1 of this invention, when calculating a standard deviation based on the result of FIG. 7, the horizontal axis represents the frequency bin and the vertical axis represents the signal intensity of the reflected signal. In Embodiment 1 of this invention, it is a figure for demonstrating the state of the reflective point at the time of drive | working the general road without a snow wall on the road side. In Embodiment 1 of this invention, when calculating a standard deviation in the state of FIG. 9, the horizontal axis shows the frequency bin and the vertical axis shows the signal intensity of the reflected signal. In Embodiment 1 of this invention, it is a figure for demonstrating the state of the reflective point at the time of drive | working the road with a snow wall on the road side. In Embodiment 1 of this invention, when calculating a standard deviation in the state of FIG. 11, it is the figure which showed the horizontal axis as the frequency bin and the vertical axis | shaft as the signal strength of the reflected signal. In Embodiment 1 of this invention, it is a figure for demonstrating the determination process of the determination conditions 3 performed by the curve road determination part.

  Hereinafter, preferred embodiments of a radar apparatus and a roadside snow wall detection method of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a structural diagram of a radar apparatus according to Embodiment 1 of the present invention. The radar apparatus 1 according to the first embodiment shown in FIG. 1 includes a transmission / reception unit 11, a frequency analysis unit 12, an object calculation unit 13, a roadside snow wall candidate determination unit 14, a standard deviation calculation unit 15, and a roadside snow wall determination unit 16. It is configured with. The roadside snow wall determining unit 16 includes a straight road determining unit 16a and a curved road determining unit 16b.

  The radar apparatus 1 radiates a transmission signal from the transmission / reception unit 11 as an electromagnetic wave. Furthermore, the transmission / reception unit 11 receives an electromagnetic wave reflected by an obstacle in front of the host vehicle, a roadside object such as a guard rail, a snow wall on the roadside, or the like as a reflected signal.

  The frequency analysis unit 12 performs A / D conversion on the transmission signal and the reflection signal, and frequency-analyzes the beat signal converted into digital data using FFT (Fast Fourier Transform) or the like. Then, the signal subjected to frequency analysis by the frequency analysis unit 12 is transmitted to the object calculation unit 13 and the roadside snow wall candidate determination unit 14.

  The object calculation unit 13 calculates the position and relative speed to the obstacle and roadside object based on the signal subjected to frequency analysis by the frequency analysis unit 12. Further, the roadside snow wall candidate determination unit 14 determines the presence / absence of a roadside snowwall candidate based on the signal frequency-analyzed by the frequency analysis unit 12.

  The standard deviation calculation unit 15 calculates the standard deviation of the frequency bin in which the roadside snow wall candidate selected by the roadside snowwall candidate determination unit 14 exists, and transmits the calculated standard deviation value to the roadside snowwall determination unit 16. .

  The roadside snow wall determination unit 16 determines whether there is a snow wall on the roadside from the standard deviation value. Further, the roadside snow wall determination unit 16 refers to the calculation result of the object calculation unit 13 as necessary by the straight road determination unit 16a and the curved road determination unit 16b, and determines whether the road ahead is a straight road or a curve. It is simply determined whether the road. And the roadside snow wall determination part 16 outputs the determined result to the exterior.

  Next, the road-side snow wall determination process and the road shape determination process in front of the traveling road executed by the radar apparatus 1 according to the first embodiment will be specifically described. FIG. 2 is a flowchart showing a series of processes executed by the radar apparatus 1 according to Embodiment 1 of the present invention.

  First, in step S100, the radar apparatus 1 determines whether or not the determination result in the previous cycle is a curved road. If the radar apparatus 1 determines that the road is a curved road in the previous cycle, the process proceeds to step S115. Operations after step S115 will be described later.

  On the other hand, if the radar apparatus 1 determines that it is not a curved road in the previous cycle, the process proceeds to step S101. In step S101, the transmission / reception unit 11 in the radar apparatus 1 radiates the transmission signal as an electromagnetic wave, and receives the reflected electromagnetic wave as a reflection signal from the snow wall on the road side ahead of the host vehicle. Further, the transmission / reception unit 11 transmits the received reflected signal to the frequency analysis unit 12.

  Next, in step S102, the frequency analysis unit 12 performs frequency analysis of the transmitted reflected signal. Next, in step S103, the roadside snow wall candidate determination unit 14 receives the signal frequency-analyzed by the frequency analysis unit 12, and determines whether there is a roadside snow wall candidate.

  Here, the presence / absence determination process of the roadside snow wall candidate in step S103 will be described with reference to FIG. FIG. 3 is a diagram showing the result of frequency analysis performed by the frequency analysis unit 12 in the first embodiment of the present invention, where the horizontal axis indicates frequency bins and the vertical axis indicates the signal strength of the reflected signal.

  As shown in FIG. 3, the roadside snow wall candidate determination unit 14 calculates a width in which bins having a reflected signal intensity equal to or higher than the first threshold are continuous. Further, the roadside snow wall candidate determination unit 14 determines whether or not the calculated width is equal to or greater than a predetermined continuous bin width.

  For example, in the case of an FMCW radar, one bin for the relative distance is calculated from C / (2 · ΔF). When the frequency is 600 MHz, one bin corresponds to 0.25 m. Here, c is the speed of light, and ΔF is the modulation width.

  When the predetermined continuous bin width is 200 bins, the distance is approximately 50 m. In FIG. 3, for simplification of description, bins from which relative velocity components have been removed are shown.

  In step S103, the road-side snow wall candidate determination unit 14 determines that there is no road-side snow wall candidate if the width in which the bins equal to or greater than the first threshold are less than the predetermined continuous bin width, and performs a series of processes. Exit. On the other hand, in step S103, the roadside snow wall candidate determination unit 14 determines that there is a roadside snowwall candidate if the width in which the bins equal to or greater than the first threshold are equal to or greater than the predetermined continuous bin width, Proceed to step S104.

  In step S <b> 104, the roadside snow wall candidate determination unit 14 corrects the amount of change due to distance with respect to each signal intensity of the continuous bins equal to or higher than the first threshold.

  In general, it is known from the radar equation that the signal intensity of the reflected signal of the radar is reduced by 1/4 of the distance. Therefore, the roadside snow wall candidate determination unit 14 stores a predetermined correction amount, calculates each signal intensity obtained by subtracting the signal change due to the distance, and proceeds to step S105.

  Next, in step S105, the roadside snow wall candidate determination unit 14 calculates the number of bins in which the signal strength of each bin subjected to the correction of the distance of each signal strength is equal to or greater than the second threshold.

  Here, the operation in step S105 will be described with reference to FIGS. FIG. 4 is an explanatory diagram showing a case where there are a plurality of other vehicles ahead when the host vehicle is running beside the snow wall in the first embodiment of the present invention. FIG. 5 is a diagram showing the result of the distance correction performed in step S104 in the state of FIG. 4 in the first embodiment of the present invention, with the horizontal axis representing the frequency bin and the vertical axis representing the signal strength of the reflected signal. is there.

  For example, as shown in FIG. 4, when there are a plurality of other vehicles ahead of the host vehicle even when the host vehicle is next to a snow wall, as shown in FIG. 5, a bin with a peak equal to or higher than the second threshold is obtained. There are several.

  On the other hand, FIG. 6 is an explanatory diagram showing a case where there are few other vehicles ahead when the host vehicle is running beside the snow wall in Embodiment 1 of the present invention. The case where there is one other vehicle is illustrated. FIG. 7 is a diagram showing the result of the distance correction performed in step S104 in the state of FIG. 6 in the first embodiment of the present invention, with the horizontal axis representing the frequency bin and the vertical axis representing the signal strength of the reflected signal. is there.

  For example, as shown in FIG. 6, when there are few other vehicles ahead of the host vehicle even if the host vehicle is next to a snow wall, as shown in FIG. Less.

  Therefore, the road-side snow wall candidate determination unit 14 determines that the presence or absence of a snow wall on the road side cannot be determined when the electromagnetic wave reflected from the snow wall cannot be received. In step S105, the road-side snow wall candidate determination unit 14 exceeds the second threshold. Calculate the number of bins in the peak.

Next, in step S106, the roadside snow wall candidate determination unit 14 determines whether or not the following determination condition 1 is satisfied.
[Determination condition 1] It is determined whether or not the ratio between the number of bins equal to or higher than the second threshold and the number of bins continuously equal to or higher than the first threshold is equal to or higher than a predetermined first ratio.

  For example, when the first ratio is 0.25, the roadside snow wall candidate determination unit 14 determines whether or not the determination condition 1 that the ratio calculated as the determination condition 1 is 0.25 or more is satisfied. . Then, when the determination condition 1 is satisfied, the road-side snow wall candidate determination unit 14 determines that the presence / absence determination of the snow wall is impossible and ends the series of processes. On the other hand, when the determination condition 1 is not satisfied, the roadside snow wall candidate determination unit 14 determines that there is no influence on the calculation of a standard deviation described later, and proceeds to step S107.

  Note that steps S104 to S106 described above can be executed by the standard deviation calculation unit 15 instead of the roadside snow wall candidate determination unit 14.

  In step S107, the standard deviation calculation unit 15 calculates the standard deviation of the signal intensity of each bin by removing the bins equal to or higher than the second threshold and the ± n bins adjacent to the bins equal to or higher than the second threshold. Proceed to step S108.

  FIG. 8 is a diagram showing the case where the standard deviation is calculated based on the result of FIG. 7 in the first embodiment of the present invention, where the horizontal axis is the frequency bin and the vertical axis is the signal intensity of the reflected signal. More specifically, in the case of FIG. 8, the standard deviation calculation unit 15 sets n = 1, and the standard of the signal strength of each remaining bin obtained by removing the signals of the five bins illustrated by the dotted line. The deviation will be calculated.

  Next, in step S108, the standard deviation calculator 15 determines whether or not there is a snow wall on the road side by determining whether or not the standard deviation calculated in step S107 is equal to or less than a predetermined value. . The concept will be described with reference to FIGS.

  FIG. 9 is a diagram for explaining a state of reflection points when traveling on a general road having no snow wall on the road side in the first embodiment of the present invention. FIG. 10 is a diagram showing the case where the standard deviation is calculated in the state shown in FIG. 9 in the first embodiment of the present invention, where the horizontal axis is the frequency bin and the vertical axis is the signal intensity of the reflected signal.

  As shown in FIG. 9, when traveling on a general road having no snow wall on the road side, the reflection from the road-side object is received with a certain distance apart. Therefore, as shown in FIG. 10, the signal intensity of the bin corresponding to the distance reflected from the roadside object increases. In addition, since roadside objects include various objects such as guardrails, trees, curbs, and sign posts, the fluctuation range of the signal intensity of the reflected signal also increases.

  On the other hand, FIG. 11 is a diagram for explaining the state of reflection points when traveling on a road having a snow wall on the road side in Embodiment 1 of the present invention. FIG. 12 is a diagram showing the case where the standard deviation is calculated in the state of FIG. 11 in the first embodiment of the present invention, where the horizontal axis represents frequency bins and the vertical axis represents the signal strength of the reflected signal.

  As shown in FIG. 11, when there is a snow wall on the road side, a guard rail or the like existing on a general road is buried in the snow wall, so that the reflection reflected from the road side and received by the transmitting / receiving unit 11 The signal is dominated by the roadside snow wall.

  Here, the snow wall on the road side is a compacted snow such as a tight snow or a rough snow, or a compacted ice lump. Therefore, as shown in FIG. 11, there are an infinite number of reflection points. When the reflected signal is subjected to frequency analysis, the signal intensity fluctuation is small as shown in FIG. 12, unlike the reflection from the general roadside object of FIG. Become.

  Therefore, in step S108, the standard deviation calculation unit 15 determines that there is a snow wall as described with reference to FIGS. 11 and 12 when the standard deviation calculated in step S107 is equal to or less than a predetermined value. Determination is made and the process proceeds to step S109.

  On the other hand, if the standard deviation calculated in step S107 exceeds a predetermined value in step S108, the standard deviation calculation unit 15 determines that there is no snow wall as described with reference to FIGS. Then, the series of processes is finished.

  When the process proceeds to step S109, the standard deviation calculation unit 15 calculates the standard deviation. Note that the standard deviation calculated in step S109 can be a standard deviation value of signal intensity averaged over one or more observation times. By performing such averaging, the presence or absence of a roadside snow wall can be more easily determined.

Next, in step S110, the straight road determination unit 16a in the roadside snow wall determination unit 16 determines whether or not the following determination condition 2 is satisfied.
[Determination condition 2] It is determined whether or not the difference between the maximum value and the minimum value of the signal intensity in the number of bins in which the bins equal to or higher than the first threshold are equal to or greater than a predetermined determination value.

  Then, if it is determined that the determination condition 2 is satisfied, the straight road determination unit 16a proceeds to step S111, determines that the road shape ahead of the host vehicle is a straight road, and the road shape is a straight road. Store and finish the series of processes. For example, when the predetermined determination value is 400 bins or more, it corresponds to considering a straight road at 100 m or more.

On the other hand, if the straight road determination unit 16a determines that the determination condition 2 is not satisfied, the process proceeds to step S112. In step S112, the curved road determination unit 16b in the road-side snow wall determination unit 16 determines whether or not the following determination condition 3 is satisfied, whereby the road shape ahead of the host vehicle is a curved road. Determine whether.
[Determination Condition 3] It is determined whether or not the object calculation unit 13 has calculated a stationary object at a distance equal to or greater than the distance corresponding to the maximum bin of the bins having the first threshold or higher.

  Here, the concept of determining that the road shape ahead of the host vehicle is a curved road according to the determination condition 3 will be described with reference to FIG. FIG. 13 is a diagram for explaining the determination process of the determination condition 3 executed by the curved road determination unit 16b in the first embodiment of the present invention.

  When the road shape in front of the host vehicle is a curved road with a snow wall, even if there is an object ahead of the snow wall, it is blocked by the snow wall. Accordingly, in this case, since the reflected signal from the object cannot be received and the object is not detected, the determination condition 3 is satisfied.

  Accordingly, when the above-described determination condition 3 is satisfied, the curved road determination unit 16b proceeds to step S114, determines that the road shape ahead of the host vehicle is a curved road, and ends the series of processes. On the other hand, if it is determined in step S112 that the road is not a curved road, the process proceeds to step S113, and determination is impossible, and the series of processes ends.

Next, the process after step S115 when it determines with Yes by previous step S100 is demonstrated. In step S100, when it is determined that the road is a curved road in the previous cycle, in step S115, the curved road determination unit 16b determines whether or not the following determination condition 4 is satisfied. It is determined whether the road shape is a curved road.
[Determination Condition 4] The first distance obtained by subtracting the movement distance from the previous cycle from the distance corresponding to the maximum bin is equal to or greater than a predetermined distance, and the object calculation unit 13 sets the distance to the distance equal to or greater than the first distance. Determine if is not calculated

  In this way, when the determination condition 4 is satisfied, the curved road determination unit 16b proceeds to step S116, determines that the curved road continues, and ends the series of processes. On the other hand, if the determination condition 4 is not satisfied, the curved road determination unit 16b proceeds to step S117, determines that determination is impossible, and ends the series of processes.

  The travel distance from the previous cycle is calculated, for example, by multiplying the average value of the vehicle speed of the previous cycle and the current cycle by the time of one cycle.

  As described above, according to the first embodiment, even when a general roadside object is buried in the snow wall and cannot be detected by the radar device, by performing signal processing based on the reflection information from the snow wall, It is possible to determine whether or not there is a snow wall and to use a simple method to detect the road shape ahead of the host vehicle using the information on the snow wall. As a result, even when a roadside object such as a card rail, a tree, or a sign post is buried in snow, the presence or absence of a roadside snow wall can be determined and the road shape ahead of the host vehicle can be estimated. A radar device can be realized.

  DESCRIPTION OF SYMBOLS 1 Radar apparatus, 11 Transmission / reception part, 12 Frequency analysis part, 13 Object calculation part, 14 Road side snow wall candidate determination part, 15 Standard deviation calculation part, 16 Road side snow wall determination part, 16a Straight road determination part, 16b Curve road determination part .

Claims (9)

A transmission / reception unit mounted on a vehicle, for transmitting a radio wave as a transmission signal in front of the host vehicle, and receiving a radio wave reflected by the transmission signal from a reflector in front of the host vehicle as a reflection signal;
A frequency analysis unit that analyzes a frequency of a beat signal of the transmission signal and the reflection signal;
Of the spectrum signal obtained from the analysis result of the frequency analysis unit, the number of consecutive bins having a signal intensity equal to or higher than a predetermined first threshold is calculated as the number of continuous bins. A roadside snow wall candidate determination unit that determines that a roadside snow wall candidate exists in the reflector, when the number of determination bins is greater than or equal to
When the roadside snow wall candidate determination unit determines that there is a roadside snowwall candidate, a standard deviation calculation unit that calculates the standard deviation of the signal intensity of each bin included in the continuous bin number;
A radar apparatus comprising: a roadside snow wall determining unit that determines that the roadside snow wall candidate is a roadside snow wall if the standard deviation calculated by the standard deviation calculating unit is equal to or less than a predetermined determination standard deviation value. The radar apparatus according to claim 1, wherein the standard deviation calculation unit calculates the standard deviation of the signal intensity after correcting a change in signal intensity due to a distance for the signal intensity of each bin included in the number of continuous bins. The standard deviation calculating unit includes ± n bins adjacent to a signal intensity equal to or higher than a predetermined second threshold and a signal intensity equal to or higher than the second threshold among signal intensity of each bin included in the number of consecutive bins. The radar apparatus according to claim 1, wherein a standard deviation of the signal intensity is calculated after removing the signal intensity. The roadside snow wall candidate determination unit determines whether or not there is a roadside snow wall when the ratio between the number of bins having a signal intensity equal to or higher than the second threshold and the number of continuous bins is equal to or higher than a predetermined first ratio. The radar apparatus according to claim 3, which is not determined. The radar device according to any one of claims 1 to 4, wherein the standard deviation calculation unit calculates the standard deviation of the signal intensity as an average value of observation times of one period or more. When the road-side snow wall determining unit determines that the road-side snow wall candidate is a road-side snow wall, a difference value between the maximum value and the minimum value of the signal strength of each bin included in the continuous bin number is determined in advance. The radar apparatus according to any one of claims 1 to 5, further including a straight road determination unit that determines that a road shape ahead of the host vehicle is a straight line if the determination value is equal to or greater than the determination value. An object calculator that calculates the position, speed, and number up to the reflector in front of the host vehicle based on the analysis result of the frequency analyzer, and detects the presence or absence of a stationary object or a moving object;
When the road-side snow wall determining unit determines that the road-side snow wall candidate is a road-side snow wall, a difference value between the maximum value and the minimum value of the signal strength of each bin included in the continuous bin number is determined in advance. If a stationary object is not detected by the object calculation unit at a distance equal to or greater than the maximum bin included in the number of continuous bins, the road shape ahead of the host vehicle is The radar apparatus according to claim 1, further comprising a curved road determination unit that determines that the road is a curved road. The curved road determination unit determines that the road is a curved road in the previous cycle, and the object calculation unit performs a stationary object at a distance equal to or greater than the distance obtained by subtracting the movement distance from the previous cycle from the distance corresponding to the maximum bin. The radar device according to claim 7, wherein when the vehicle is not detected, the road shape ahead of the host vehicle is determined to be a curved road. A roadside snow wall detection method executed in the radar device according to any one of claims 1 to 8,
A first step of performing frequency analysis on a beat signal of a transmission signal that is a radio wave transmitted in front of the host vehicle and a reflection signal obtained by reflecting the transmission signal on a reflector existing in front of the host vehicle; ,
A second step of calculating, as a continuous bin number, the number of consecutive bins having a signal intensity equal to or higher than a predetermined first threshold among the spectrum signals obtained from the frequency analysis result of the first step;
A third step of determining that a roadside snow wall candidate is present in the reflector when the number of continuous bins is equal to or greater than a predetermined number of determination bins;
A fourth step of calculating a standard deviation of the signal intensity of each bin included in the number of continuous bins when it is determined in the third step that a roadside snow wall candidate exists;
A road-side snow wall detection method comprising: a fifth step of determining that the road-side snow wall candidate is a road-side snow wall if the standard deviation calculated in the fourth step is equal to or less than a predetermined determination standard deviation value.

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