Radar device

Abstract

A radar device 200 according to one embodiment of the present invention is configured to: integrate (e.g., coherently integrate) the reception levels of reflected waves corresponding to radar transmission waves using one of two integration schemes, specifically coherent integration or incoherent integration; execute a process for detecting abnormalities on the basis of the result of integrating the reception levels of the reflected waves; and, in cases in which an abnormality candidate that could be an abnormality is detected through the detection process, integrate (e.g., incoherently integrate) the reception levels of reflected waves in the direction where the abnormality candidate was detected using the other of the two integration schemes in the next radar operation.

Description

Technical Field

[0001] The present invention relates to a radar device that performs a radar operation for measuring the reception level of a reflected wave with respect to a transmission wave.

Background Art

[0002] As a radar device using microwaves, millimeter waves, etc., there is, for example, an FMCW (Frequency Modulated Continuous-Wave) radar device having a structure as shown in FIG. 1. The radar device 100 in FIG. 1 amplifies a frequency-modulated radar signal from an FMCW transmission source 101 with a transmission power amplifier 103 and transmits it from a transmission antenna 104. When an object T (reflector) exists within the detection range of the radar device 100, the radar transmission wave is reflected by the object T. The reflected wave from the object T is received by the reception antenna 105 of the radar device 100, amplified by the reception power amplifier 106, and then mixed by a mixer 107 with the transmission radar signal component from a power distributor 102 and converted into an IF signal. The IF signal output from the mixer 107 is A / D converted and signal-processed by a signal processing unit 108. As a result, radar detection results such as the reflected reception power (reflected wave power) of the object T, the distance to the object T, the azimuth of the object T (angle as seen from the radar device 100), and the speed (relative speed with respect to the radar device 100) when the object T is moving are obtained.

[0003] As prior arts in the technical field related to the present invention, there are the following. For example, Patent Document 1 discloses a radar system that controls the angle of an antenna based on the positional relationship between a reference reflector installed at a predetermined position, the antenna of the radar device, and the detection range of the radar device, and the reception result of the reflected wave from the reference reflector by the antenna. Further, Patent Document 2 discloses a radar system including a plurality of object shape acquisition devices installed at different positions and configured to acquire shape information of an object detected by a radar device as seen from the self-position, and a display device configured to display an object shape image based on the plurality of shape information acquired by the plurality of object shape acquisition devices. Further, Patent Document 3 discloses a monitoring management system that receives a user designation of a first monitoring area in the measurement ranges of a plurality of radar devices, stores the position information of the first monitoring area in monitoring area management information, selects the measurement data values of the measurement points included in the first monitoring area from the measurement data values of the plurality of radar devices, determines the presence or absence of a foreign object in the first monitoring area based on the selected measurement data values, and outputs a monitoring result image indicating the presence or absence of a foreign object in the first monitoring area.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] As a use of the radar device, there is a use for detecting foreign objects existing on road surfaces such as roads and runways. For example, in a system for detecting foreign objects on an airport runway, a linear cell radar system in which a plurality of radar devices are arranged side by side along the runway is adopted so as to be able to monitor a wide area. Here, there are usually no foreign objects such as dropped objects or abandoned objects on the airport runway. Therefore, the radar device continuously sends radar transmission waves to the detection range and detects the foreign object based on the received wave (reflected wave) that appears when any foreign object exists within the detection range.

[0006] The radar device used for the above-described use performs a radar operation of measuring the reception level of the reflected wave with respect to the radar transmission wave while rotating so as to scan the detection range in an arc shape. Here, when the RCS (Radar cross-section) of the foreign object is small, the reception level of the reflected wave from the foreign object also becomes small. As a result, as shown in FIG. 2, the reflected wave from the foreign object is buried in the noise generated by the weather conditions and the surrounding environment, making it difficult to find, so it takes time to detect the foreign object, and in some cases, the foreign object cannot be detected.

[0007] The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to improve the accuracy of detecting foreign objects by a radar device that measures the reception level of the reflected wave with respect to the radar transmission wave.

Means for Solving the Problem

[0008] In order to achieve the above object, a radar device according to an aspect of the present invention is configured as follows. That is, in a radar device that performs a radar operation for measuring the reception level of a reflected wave with respect to a radar transmission wave, the reception level of the reflected wave is integrated by one of two integration methods, coherent integration and incoherent integration, and based on the integration result of the reception level of the reflected wave, a foreign object detection process is executed. When a foreign object candidate that may be a foreign object is detected by the detection process, in the next radar operation, the reception level of the reflected wave in the direction where the foreign object candidate is detected is integrated by the other of the two integration methods.

[0009] Here, in the radar device according to the present invention, when a foreign object candidate is detected by the detection process, in the next radar operation, the radar rotation speed in the direction where the foreign object candidate is detected may be configured to change.

[0010] Also, in the radar device according to the present invention, when a foreign object candidate is detected by the detection process, the radar rotation direction may be configured to temporarily change in the reverse direction.

Advantages of the Invention

[0011] According to the present invention, it is possible to improve the accuracy of foreign object detection by a radar device that measures the reception level of a reflected wave with respect to a radar transmission wave.

Brief Description of the Drawings

[0012]

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Embodiments for Carrying Out the Invention

[0013] An embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows a configuration example of a radar system according to an embodiment of the present invention. The radar system of this example includes a radar device 200 and a camera device 220 installed facing a predetermined detection range R such as a runway, and a radar monitoring device 300 and a display device 320 installed in a control room or a monitoring room in an air traffic control tower. In FIG. 3, only one radar device 200 and one camera device 220 are shown, but a plurality of radar devices 200 and camera devices 220 may be provided.

[0014] The radar device 200 receives the reflected wave of the radar transmission wave transmitted to the detection range R, and outputs the result of signal processing to the radar monitoring device 300. The radar monitoring device 300 causes the display device 320 to display the position information of an object (foreign object such as a dropped object or an abandoned object) T existing within the detection range R based on the data output from the radar device 200. The radar monitoring device 300 further controls the camera device 220 based on the position information of the object T, and causes the display device 320 to display an image obtained by photographing the object T. As a result, a monitor who views the display on the display device 320 can confirm the position and appearance of the object T detected by the radar device 200, and can instruct an operator to remove it if it is a foreign object.

[0015] As described above, in a conventional radar device, when the RCS of an object existing within the detection range R is small, the reflected wave from the object is buried in noise and becomes difficult to find. As a result, it takes time to detect a foreign object, and in some cases, the foreign object cannot be detected as such. As a countermeasure against such a problem, the radar device 200, which is an example of the present invention, has a function of integrating the reception level of the reflected wave with respect to the radar transmission wave.

[0016] The radar device 200 in this example can selectively use two integration methods: coherent integration, which is integration in the time domain, and incoherent integration, which is integration in the frequency domain. When coherent integration is performed, as illustrated in FIG. 4, the reception level of the reflected wave from the foreign object remains unchanged, and only the noise is averaged. When incoherent integration is performed, as illustrated in FIG. 5, the reception level of the reflected wave from the foreign object remains unchanged, the noise becomes rough and fluctuates, but the level decreases. In the graphs of FIGS. 4 and 5, the horizontal axis represents the distance from the radar device 200, and the vertical axis represents the reception level of the reflected wave (including noise). Thus, by performing coherent integration or incoherent integration on the reception level of the reflected wave with respect to the radar transmission wave, it becomes easier to detect the reflected wave from the foreign object.

[0017] In this example, coherent integration is used as the basis, and when a foreign object candidate that may be a foreign object is detected, it is set to use incoherent integration in the next radar operation in the detection direction. That is, in the normal radar operation (before detecting a foreign object candidate), the radar device 200 performs coherent integration on the reception level of the reflected wave with respect to the radar transmission wave to execute the foreign object detection process. On the other hand, in the next radar operation when a foreign object candidate is detected, the radar device 200 performs incoherent integration on the reception level in the detection direction to re - execute the foreign object detection process. By using two types of integration methods with different characteristics in this way, further improvement in the detection accuracy of foreign objects is achieved. Note that, conversely, it may be set to use incoherent integration as the basis and use coherent integration in the next radar operation when a foreign object candidate is detected.

[0018] The operation of the radar device 200 will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram showing an example of radar operation when a foreign object candidate is detected. FIG. 7 is a diagram showing an example of the next radar operation when a foreign object candidate is detected. As shown in these figures, the radar device 200 performs radar operation while rotating so as to scan the detection range R in an arc shape. In this example, the antenna of the radar device 200 is mechanically rotated to perform radar operation, but the present invention is not limited to such a configuration. For example, an array antenna composed of a plurality of antenna elements may be provided in the radar device 200, and the radar operation may be performed by a beam scanning method in which the beam angle of the radar transmission wave is electronically changed by controlling the phase shift amount of each antenna element.

[0019] In the radar operation at a certain timing, as a result of performing the detection process of a foreign object by coherently integrating the reception level of the reflected wave with respect to the radar transmission wave, it is assumed that a signal having a possibility of being a foreign object (for example, about +1 dB with respect to noise) is found (see FIG. 6). At this time, the radar device 200 determines that a foreign object candidate has been detected, but the probability that it is a foreign object is not very high. In the next radar operation when a foreign object candidate is detected, the radar device 200 re-executes the detection process of a foreign object by incoherently integrating the reception level of the reflected wave in a target range Ra of a predetermined angle (for example, ±10°) centered on the detection direction of the foreign object candidate. As a result, the level difference between the foreign object candidate and the noise becomes clear at about 2 dB, and the probability that it is a foreign object increases (see FIG. 7). Note that in the next radar operation when a foreign object candidate is detected, the radar device 200 normally performs the detection process of a foreign object by coherently integrating the reception level of the reflected wave for the portion other than the target range Ra in the detection range R.

[0020] Here, in the above embodiments, in the next radar operation when a foreign object candidate is detected, the integration method of the reception level in the detection direction is switched. However, the radar rotation speed may be changed along with the switching of the integration method. For example, normally, while performing radar operation at a rotation speed suitable for coherent integration, the reception level of the reflected wave is coherently integrated to execute foreign object detection processing. On the other hand, in the next radar operation when a foreign object candidate is detected, the radar rotation speed in the target range Ra is changed to a rotation speed suitable for non-coherent integration, and the reception level of the reflected wave is non-coherently integrated to execute foreign object detection processing again. Thereby, it becomes possible to further improve the detection accuracy of foreign objects.

[0021] Also, when a foreign object candidate is detected, the radar rotation direction may be temporarily changed in the reverse direction. For example, normally, while performing a counterclockwise radar operation, the reception level of the reflected wave is coherently integrated to execute foreign object detection processing. Then, when a foreign object candidate is detected, the radar operation is switched to a clockwise operation so as to scan the target range Ra in the reverse direction, and the reception level of the reflected wave is non-coherently integrated to execute foreign object detection processing again. At this time, the radar rotation speed may be changed to a rotation speed suitable for non-coherent integration. After finishing the reverse scan of the target range Ra, return to the normal counterclockwise radar operation and coherently integrate the reception level of the reflected wave to execute foreign object detection processing. Thereby, not only can the detection accuracy of foreign objects be improved, but also the time required for foreign object detection can be shortened.

[0022] Also, when a foreign object candidate is detected, the angle of the radar transmission wave in the vertical direction may be changed. For example, normally, the radar transmission wave is transmitted at an angle that covers the detection range R, and the reception level of the reflected wave is coherently integrated to execute foreign object detection processing. On the other hand, in the next radar operation when a foreign object candidate is detected, the radar transmission wave is transmitted at an angle that is optimal for the distance to the foreign object candidate, and the reception level of the reflected wave is non-coherently integrated to execute foreign object detection processing.

[0023] Also, when a foreign object candidate is detected, the beam width of the radar transmission wave may be changed. For example, during normal operation, the radar transmission wave is transmitted with a relatively wide beam width, and the reception level of the reflected wave is coherently integrated to perform foreign object detection processing. On the other hand, in the next radar operation when a foreign object candidate is detected, the radar transmission wave is transmitted with a narrower beam width, and the reception level of the reflected wave is incoherently integrated to perform foreign object detection processing.

[0024] In this example, the radar device 200 autonomously performs the above control (such as switching the integration method, changing the radar rotation speed, changing the radar rotation direction, etc.) associated with the detection of foreign object candidates. However, the above control may also be performed according to a control command from another device. For example, the radar monitoring device 300 may determine the necessity of the above control based on the data output from the radar device 200 and send a control command to the radar device 200.

[0025] Also, when using such a radar monitoring device 300, the image captured by the camera device 220 may be utilized to determine the necessity of the above control. For example, when a foreign object candidate is detected, the camera device 220 captures the foreign object candidate, and the image is subjected to analysis processing or confirmed by a monitor. As a result, if it is determined that it is a foreign object, the above control is not executed. On the other hand, when it is determined that it is unclear whether it is a foreign object, the above control is executed. This makes it possible to more efficiently detect foreign objects.

[0026] As described above, the radar device 200 in this example integrates the reception level of the reflected wave with respect to the radar transmission wave by one of two integration methods, coherent integration and incoherent integration (for example, coherent integration), and based on the integration result of the reception level of the reflected wave, executes a foreign object detection process. When a foreign object candidate, which may be a foreign object, is detected by the detection process, in the next radar operation, the reception level of the reflected wave in the direction where the foreign object candidate is detected is integrated by the other of the two integration methods (for example, incoherent integration). Therefore, since the foreign object detection process can be executed using two types of integration methods with different characteristics, it is possible to further improve the detection accuracy of foreign objects.

[0027] In the above description, the integration method is switched when a foreign object candidate is detected, but the integration method may be switched regardless of the detection of the foreign object candidate. That is, a step of integrating the reception level of the reflected wave by one of the two integration methods, coherent integration and incoherent integration, a step of executing a foreign object detection process based on the result of integrating the reception level of the reflected wave by one of the integration methods, a step of switching the integration method used for integrating the reception level of the reflected wave to the other of the two integration methods, a step of integrating the reception level of the reflected wave by the other integration method, and a step of executing a foreign object detection process based on the result of integrating the reception level of the reflected wave by the other integration method may be implemented. The switching of the integration method can be performed, for example, every time the radar makes one rotation.

[0028] The embodiments of the present invention have been described above, but these embodiments are merely examples and do not limit the technical scope of the present invention. The present invention can take various other embodiments, and various modifications such as omission and substitution can be made without departing from the gist of the present invention. These embodiments and their modifications are included in the scope and gist of the invention described in this specification and the like, and are also included in the invention described in the claims and its equivalent scope.

[0029] Furthermore, the present invention can be provided not only as the devices as described above and a system composed of these devices, but also as a method executed by these devices, a program for causing a processor to realize the functions of these devices, a storage medium that stores such a program in a computer-readable manner, and the like.

Industrial Applicability

[0030] The present invention can be used in a radar device that performs a radar operation for measuring the reception level of a reflected wave with respect to a transmission wave.

Explanation of Signs

[0031] 100: Radar device, 101: FMCW transmission source, 102: Power distributor, 103: Transmission power amplifier, 104: Transmission antenna, 105: Reception antenna, 106: Reception power amplifier, 107: Mixer, 108: Signal processing unit, 200: Radar device, 220: Camera device, 300: Radar monitoring device, 320: Display device

Claims

1. In a radar device that performs a radar operation for measuring the reception level of a reflected wave with respect to a radar transmission wave, integrating the reception level of the reflected wave by one of two integration methods, namely coherent integration and incoherent integration; executing a foreign object detection process based on the integration result of the reception level of the reflected wave; When a foreign object candidate that may be a foreign object is detected by the detection process, in the next radar operation, integrating the reception level of the reflected wave in the direction where the foreign object candidate is detected by the other of the two integration methods. A radar device characterized by this.

2. In the radar device according to Claim 1, When the foreign object candidate is detected by the detection process, in the next radar operation, changing the radar rotation speed in the direction where the foreign object candidate is detected. A radar device characterized by this.

3. In the radar device according to Claim 1, When the foreign object candidate is detected by the detection process, temporarily changing the radar rotation direction to the reverse direction. A radar device characterized by this.

4. In the radar device according to Claim 2, When the foreign object candidate is detected by the detection process, temporarily changing the radar rotation direction to the reverse direction. A radar device characterized by this.

5. A method for measuring the reception level of a reflected wave with respect to a radar transmission wave, comprising: integrating the reception level of the reflected wave by one of two integration methods, namely coherent integration and incoherent integration; executing a foreign object detection process based on the result of integrating the reception level of the reflected wave by the one integration method; switching the integration method used for integrating the reception level of the reflected wave to the other of the two integration methods; integrating the reception level of the reflected wave by the other integration method; and executing a foreign object detection process based on the result of integrating the reception level of the reflected wave by the other integration method. A reception level measurement method characterized by this.

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