Peripheral surveillance radar equipment

Abstract

This makes it possible to determine the road surface condition of the road being driven on. [Solution] A surrounding monitoring radar device 1 mounted on a tractor T transmits radar to the surroundings and receives reflected waves to monitor the surroundings, and includes a road surface condition determination unit that transmits radar to the road surface R at first predetermined time intervals to acquire the signal strength of the reflected waves from the road surface R, accumulates the signal strength for a second predetermined time interval which is longer than the first predetermined time interval, calculates at least one of the variance value and the maximum value of the accumulated signal strength, repeats this calculation process a predetermined number of times while shifting by the first predetermined time interval, and determines the state of the road surface R based on the calculation result.

Description

Technical Field

[0001] The present invention relates to a peripheral monitoring radar device that monitors the surroundings with a radar.

Background Art

[0002] When mounting a millimeter-wave radar device on a mobility moving object to monitor the surroundings, various techniques for suppressing clutter on the road surface have been conventionally proposed, and a technique for suppressing clutter on the road surface by dynamic threshold processing (Cell-Averaging Constant False Alarm Rate, hereinafter referred to as "CA-CFAR") is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, there are cases where it is desired to determine whether the place to travel is a paved road or a field (farm) according to the type of mobility and the purpose of travel. However, in the CA-CFAR described in Patent Document 1, it is not only necessary to set a plurality of parameters and is complicated, but it is also difficult to determine what state the traveling road is in.

[0005] Therefore, an object of the present invention is to provide a peripheral monitoring radar device capable of determining what kind of road surface state the traveling road is in.

Means for Solving the Problems

[0006] To solve the above problems, the invention described in claim 1 is a surrounding monitoring radar device mounted on a mobility device that transmits radar to the surroundings and receives reflected waves to monitor the surroundings, and is characterized by comprising a road surface condition determination unit that transmits radar to the road surface, obtains the signal strength of the reflected waves from the road surface, and determines the state of the road surface based on the characteristic quantities of the signal strength.

[0007] The invention described in claim 2 is characterized in that, in the surrounding monitoring radar device described in claim 1, the road surface condition determination unit is capable of determining various road surface conditions based on the feature quantities.

[0008] The invention described in claim 3 is characterized in that, in the surrounding monitoring radar device described in claim 1, the road surface condition determination unit transmits radar to the road surface at first predetermined time intervals to obtain the signal strength of the reflected wave from the road surface, accumulates the signal strength for a second predetermined time interval which is longer than the first predetermined time interval, calculates at least one of the variance value and the maximum value of the accumulated signal strength, repeats this calculation process a predetermined number of times while shifting by the first predetermined time interval, and determines the condition of the road surface based on the calculation result.

[0009] The invention described in claim 4 is characterized in that, in the surrounding monitoring radar device described in claim 3, the road surface condition determination unit determines the condition of the road surface based on predetermined thresholds for the dispersion value and maximum value of the signal intensity, and the predetermined thresholds are changeable. [Effects of the Invention]

[0010] According to the invention described in claim 1, the condition of the road surface is determined based on characteristic quantities determined by the signal intensity of the reflected wave. In other words, the condition of the road surface is determined based on characteristic quantities such as the variance and maximum value of the signal intensity. For example, if the variance or maximum value is large, the road surface is determined to be rough (uneven), making it possible to determine the condition of the road surface.

[0011] According to the invention described in claim 2, since various road surface conditions can be determined by feature quantities (for example, by changing the criteria for determining feature quantities), it becomes possible to determine various types of road surfaces (for example, whether it is a paved road or a field).

[0012] According to the invention described in claim 3, the signal intensity of reflected waves from the road surface acquired at first predetermined time intervals is accumulated for a second predetermined time interval, and the condition of the road surface is determined based on the dispersion value and maximum value. For example, if the dispersion value or maximum value is large, it is determined that the road surface is rough (uneven), making it possible to determine the condition of the road surface. Moreover, since the calculation process of accumulating the signal intensity of reflected waves from the road surface for a second predetermined time interval and calculating the dispersion value and maximum value is repeated a predetermined number of times while shifting by the first predetermined time interval, it is possible to determine the condition of the road surface appropriately and accurately.

[0013] According to the invention described in claim 4, since the threshold for determining the condition of the road surface is changeable, it is possible to determine various types of road surfaces by changing the threshold according to the type of road surface to be known (for example, paved road or field). [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic block diagram showing a peripheral monitoring radar device according to an embodiment of the present invention. [Figure 2] Figure 1 shows a conceptual diagram (a) illustrating the surrounding monitoring radar system mounted on a tractor and transmitting and receiving radar signals, and Figure (b) showing the measurement area by the radar. [Figure 3] This figure shows the determination method used by the road surface condition determination unit of the surrounding monitoring radar device shown in Figure 1. [Figure 4] Figure 1 shows an example of the road surface condition determination unit of the surrounding monitoring radar device calculating the variance value of signal strength for different road surfaces (Figure (a)) and an example of the maximum value of signal strength calculated (Figure (b)). [Figure 5] This figure shows the determination flow of the road surface condition determination unit of the surrounding monitoring radar device shown in Figure 1. [Modes for carrying out the invention]

[0015] The present invention will be described below based on the illustrated embodiments.

[0016] Figures 1 to 5 illustrate embodiments of this invention, with Figure 1 being a schematic block diagram showing a peripheral monitoring radar device 1 according to this embodiment. This peripheral monitoring radar device 1 is mounted on a mobility vehicle and transmits radar to the surroundings from a transmitting unit 2, receives reflected waves from a receiving unit 3, and processes the reflected waves and received signals in a signal processing unit 4 to monitor the surroundings. Except for the inclusion of a road surface condition determination unit 5, it has the same configuration as commercially available and existing peripheral monitoring radar devices.

[0017] The road surface condition determination unit 5 is a processing determination unit that determines the condition and type of the road surface R on which the mobility vehicle is traveling. In this embodiment, as shown in Figure 2(a), a surrounding monitoring radar device 1 is mounted on the front of a tractor T, which is an industrial mobility vehicle, and the condition and type of the road surface R on which the tractor T is traveling is determined. However, this can also be applied to other mobility vehicles and road surfaces R.

[0018] The road surface condition determination unit 5 is activated when it is necessary to determine the condition of the road surface R. In this embodiment, it is automatically activated when the tractor T's engine is started, but it may also be set to be automatically activated periodically or to be manually activated at any time.

[0019] When it is activated, first, the radar is transmitted from the transmission unit 2 to the road surface R every first predetermined time. Here, the area (measurement area) on the road surface R where the radar is transmitted is, as shown in Fig. 2(b), an area evenly distributed on the left and right in front of the tractor T, and is set so that the state of the road surface R can be appropriately determined. For example, on the front axis (Y-axis) at the center of the tip of the tractor T, it is set in an area from 5.0 m to 8.5 m from the tip of the tractor T, and on the left and right axes (X-axis) perpendicular to the front axis, in an area of 2 m on each side. Also, the first predetermined time is set to a time such that the state of the road surface R can be appropriately and quickly determined, and in this embodiment, it is set to 100 ms.

[0020] Next, the reflected wave from the road surface R is received by the receiving unit 3, and the reflected wave / received signal is signal-processed by the signal processing unit 4 to sequentially acquire radar point cloud data (hereinafter referred to as "point cloud data") including the signal intensity of the reflected wave / received signal. This point cloud data includes, in addition to the signal intensity of the reflected wave / received signal, distance, azimuth, and speed (Doppler relative speed).

[0021] Subsequently, as shown in Fig. 3, such point cloud data (signal intensity) is accumulated for a second predetermined time longer than the first predetermined time. Here, the second predetermined time is set to a time such that the state of the road surface R can be appropriately and quickly determined, and in this embodiment, it is set to 2 s. That is, the point cloud data acquired at 100 ms intervals from t = 1 (100 ms) to t = 20 (2 s) is accumulated for 20 scans.

[0022] Next, at least one of the variance value and the maximum value of the signal intensity in the accumulated point cloud data is calculated. In this embodiment, both the variance value and the maximum value are calculated. That is, for the signal intensity for 20 scans acquired at 100 ms intervals from t = 1 (100 ms) to t = 20 (2 s), the variance value and the maximum value are calculated as statistical values.

[0023] This calculation process (calculation of statistical values) is repeated a predetermined number of times, with a first predetermined time shift. Specifically, point cloud data is acquired and stored at 100ms intervals from t=2 (200ms) to t=21 (2.1s), with a shift of 100ms, and the variance and maximum value of the signal intensity are calculated as statistical values. Furthermore, point cloud data is acquired and stored at 100ms intervals from t=3 (300ms) to t=22 (2.2s), with a shift of 100ms, and the variance and maximum value of the signal intensity are calculated as statistical values. This calculation is repeated a predetermined number of times.

[0024] Here, the predetermined number of times is set to a number that allows for a proper and rapid determination of the road surface R, and in this embodiment, it is set to 5 times. In other words, five statistical values ​​are calculated over a period of 2.4 seconds, from t=1 to t=20, from t=2 to t=21, from t=3 to t=22, from t=4 to t=23, and from t=5 to t=24.

[0025] Next, the state and type of the road surface R are determined based on the five calculated statistical values. That is, the state and type of the road surface R are determined based on the calculated variance and maximum value of the signal intensity and their respective predetermined thresholds. In this embodiment, we will describe the case of determining whether the road surface R is a paved road (asphalt paved road) or a field (other than an asphalt paved road), but it is also applicable to determining other locations other than paved roads.

[0026] Prior to this, the variance values ​​of signal intensity when the road surface R is a paved road and when the road surface R is a field were measured in multiple paved roads and fields at different locations, as shown in Figure 4(a). It was confirmed that variance value C1 is the approximate boundary between the paved road and the field, with areas above variance value C1 being fields and areas below variance value C1 being paved roads. Similarly, prior to this, the maximum value of signal intensity when the road surface R is a paved road and when the road surface R is a field were measured, as shown in Figure 4(b). It was confirmed that the maximum value C2 is the approximate boundary between the paved road and the field, with areas above maximum value C2 being fields and areas below maximum value C2 being paved roads.

[0027] In this embodiment, as shown in Figure 5, if the variance values ​​of the signal intensity in the five calculated statistical values ​​are all greater than or equal to "C1+α" (the threshold value for variance) (when the result is "Y" in step S1), the road surface R is determined to be a field. Similarly, if the maximum values ​​of the signal intensity in the five calculated statistical values ​​are all greater than or equal to "C2+β" (the threshold value for maximum value) (when the result is "Y" in step S2), the road surface R is determined to be a field. In all other cases, that is, if there is a signal intensity variance value less than "C1+α" and there is a signal intensity maximum value less than "C2+β", the road surface R is determined to be a paved road.

[0028] Here, "α" and "β" are set to appropriately determine the state and type of the road surface radius (R) based on the variance and maximum value of the measured signal intensity, as shown in Figures 4(a) and (b). Furthermore, predetermined thresholds, namely the thresholds for the variance and maximum value, can be changed according to the type of road surface radius (R) to be determined. For example, when determining whether the road surface radius (R) is paved or a rice paddy, the thresholds for the variance and maximum value can be changed accordingly.

[0029] Thus, this surrounding monitoring radar device 1 accumulates the signal intensity of reflected waves from the road surface R acquired at a first predetermined time interval (100 ms) for a second predetermined time interval (2 s), and determines the state of the road surface R based on its variance and maximum value. For example, if the variance or maximum value of the signal intensity is large, it is determined that the road surface R is rough (uneven) and is a field, making it possible to determine the road surface condition of the road. Moreover, since the calculation process of accumulating the signal intensity of reflected waves from the road surface R for a second predetermined time interval (2 s) and calculating the variance and maximum value is repeated a predetermined number of times with a first predetermined time interval (100 ms) shift, it is possible to determine the state of the road surface R appropriately and accurately.

[0030] Furthermore, since the thresholds for determining the condition and type of road surface radius (dispersion threshold and maximum value threshold) can be changed, it becomes possible to determine a variety of road surface radius types by changing the thresholds according to the type of road surface radius you want to know (for example, paved road or rice paddy).

[0031] Although embodiments of this invention have been described above, the specific configuration is not limited to the embodiments described above, and any design changes, etc., that do not depart from the gist of this invention are also included. For example, in the embodiments described above, the state and type of the road surface R are determined based on the dispersion value and the maximum value of the signal intensity of the reflected wave from the road surface R, but depending on the type of road surface R to be determined and the surrounding environment, the determination may be made based on only one of them.

[0032] Furthermore, the determination flow and procedure of the road surface condition determination unit 5 are not limited to the above embodiment, and may differ depending on the type of road surface R to be determined and the purpose of determination. For example, in step S1 of Figure 5, if at least one of the signal intensity dispersion values ​​is "C1 + α" or greater, the road surface R may be determined to be a field, or in step S2 of Figure 5, if at least one of the signal intensity maximum values ​​is "C2 + β" or greater, the road surface R may be determined to be a field.

[0033] 1. Surrounding radar system 2. Transmitter 3. Receiving Unit 4. Signal Processing Unit 5. Road surface condition determination unit T Tractor (Mobility) R Road surface

Claims

1. A peripheral surveillance radar system mounted on a mobility device that transmits radar signals to the surroundings and receives reflected waves to monitor the surroundings, The system includes a road surface condition determination unit that transmits radar to the road surface to acquire the signal strength of the reflected wave from the road surface and determines the condition of the road surface based on the characteristic quantities of the signal strength. A peripheral surveillance radar device characterized by the following features.

2. The road surface condition determination unit is capable of determining various road surface conditions based on the feature quantities. The peripheral monitoring radar device according to feature 1.

3. The road surface condition determination unit transmits radar to the road surface at first predetermined intervals to obtain the signal strength of the reflected waves from the road surface, accumulates the signal strength for a second predetermined interval which is longer than the first predetermined interval, and calculates at least one of the variance value and the maximum value of the accumulated signal strength. This calculation process is repeated a predetermined number of times with a shift of the first predetermined interval, and the road surface condition is determined based on the calculation result. The peripheral monitoring radar device according to feature 1.

4. The road surface condition determination unit determines the road surface condition based on predetermined thresholds for the variance and maximum value of the signal intensity, and the predetermined thresholds are changeable. The peripheral monitoring radar device according to feature 3.

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