Processing device, processing method, and program

Abstract

A processing device 1 comprises a calculation unit 21 that calculates respective positions for a plurality of reflectors R so that the positions of three or more of the plurality of reflectors R on a prescribed plane P can be identified by measurement with a millimeter-wave radar 111. The calculation unit 21 calculates respective positions for the plurality of reflectors R at which the difference in distance between the millimeter-wave radar 111 and each reflector R is equal to or greater than the distance resolution of the millimeter-wave radar 111.

Description

Processing device, processing method, and program

[0001] The present disclosure relates to a processing device, a processing method, and a program.

[0002] There are technologies for measuring the landing point of a drone using a camera, LiDAR (Light Detection and Ranging), and millimeter-wave radar (see Non-Patent Documents 1 to 8). Non-Patent Document 8 discloses a technology for embedding a reflector in the landing surface of a drone and estimating the slope of the landing surface using millimeter-wave radar. Since Non-Patent Document 8 uses millimeter-wave radar, it is possible to estimate the landing surface even in poor visibility conditions.

[0003] Non-Patent Document 9 discloses that a type of eigenvalue analysis called Root-MUSIC is applied to the analysis of the time series signal of the reflected wave received by the millimeter wave radar, thereby estimating the position of the reflection point with high accuracy.

[0004] Phong Ha Nguyen, et al. 5 others, "LightDenseYOLO: A fast and Accurate Marker Tracker for Autonomous UAV Landing by Visible Light Camera Sensor on Drone", Sensors 2018, 18, 24 May, 2018 Jonghwi Kim, et al. 2 others, "Lidar-guided Autonomous Landing of an Aerial Vehicle on a Ground Vehicle", 2017 14th International Conference on Ubiquitous Robots and Ambient Intelligence (URAI), IEEE, 2017, June 28 - July 1, 2017 Akash Deep Singh, et al. 3 others, "RADHAR: Human Activity Recognition from Point Clouds Generated through a Millimeter-wave Radar", Proceedings of the 3rd ACM Workshop on Millimeter-wave Networks and Sensing Systems, October 25, 2019, p.51-p.56 Girish Tiwari, et al. 2 others, "mmFiT: Contactless Fitness Tracker Using mmWave Radar and Edge Computing Enabled Deep Learning", IEEE INTERNET OF THINGS JOURNAL, 2021 Jaime Lien, et al. 7 others, "Soli: Ubiquitous Gesture Sensing with Millimeter Wave Radar", ACM Transactions on Graphics, Vol.35, No.4. Article 142, July 2016 Christopher Doer, 3 others, "Radar Based Autonomous Precision Takeoff and Landing System for VTOLs in GNSS Denied Environments", 2020 International Conference on Unmanned Aircraft Systems (ICUAS), IEEE, 2020, September 1 - 4, 2020 Tatsuya Iizuka, 5 others, "MilliSign: mmWave-Based Passive Signs for Guiding UAVs in Poor Visibility Conditions", Proceedings of the 29th Annual International Conference on Mobile Computing and Networking. 2023, October 2 - 6, 2023, p.752 - p.766 Tatsuya Iizuka, 5 others, "An inclination estimation method for UAV landing surfaces using millimeter wave radar", in IGARSS 2023 - 2023 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2023, p.2049 - p.2052. Tatsuya Iizuka, 3 others, "Root-MUSIC Based Power Estimation Method with Super-Resolution FMCW Radar", 2020 IEEE / MTT-S International Microwave Symposium (IMS), IEEE, 2020, p.1027 - p.1030.

[0005] Non-Patent Document 8 assumes that all reflectors embedded in the landing surface can be accurately measured by a millimeter wave radar. However, depending on the arrangement of the reflectors, there is a problem that the accuracy required for detecting reflectors cannot be achieved, such as a decrease in the accuracy of estimating the slope of the landing surface.

[0006] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a technology that can identify the positions of multiple reflectors using radar and determine the arrangement of reflectors.

[0007] A processing device according to one aspect of the present disclosure includes a calculation unit that calculates the position of each of three or more reflectors on a predetermined surface so that the positions of the reflectors can be identified by measurements using a millimeter-wave radar, and the calculation unit calculates the position of each of the reflectors such that the difference in distance between the millimeter-wave radar and each reflector is equal to or greater than the distance resolution of the millimeter-wave radar.

[0008] A processing method according to one aspect of the present disclosure includes a computer calculating the positions of three or more reflectors on a predetermined surface so that the positions of the reflectors can be identified by measurements using a millimeter-wave radar, and the computer calculating the positions of the reflectors such that the difference in distance between the millimeter-wave radar and each reflector is equal to or greater than the distance resolution of the millimeter-wave radar.

[0009] A program according to one aspect of the present disclosure causes a computer to function as a calculation unit that calculates the positions of three or more reflectors on a predetermined surface so that the positions of the reflectors can be identified through measurements using a millimeter-wave radar, and the calculation unit calculates the positions of the reflectors such that the difference in distance between the millimeter-wave radar and each reflector is equal to or greater than the distance resolution of the millimeter-wave radar.

[0010] According to the present disclosure, it is possible to provide a technology that can identify the positions of multiple reflectors using radar and determine the arrangement of reflectors.

[0011] FIG. 1 is a diagram illustrating functional blocks of a processing device according to the present disclosure. FIG. 2 is a diagram illustrating a system configuration of a flight control system assumed by the processing device according to the present disclosure. FIG. 3 is a diagram illustrating a first perspective for determining a reflector installation position. FIG. 4 is a diagram illustrating a second perspective for determining a reflector installation position. FIG. 5 is a flowchart illustrating an example of the operation of the processing device. FIG. 6 is a diagram illustrating parameters in a processing method. FIG. 7 is a diagram illustrating the area of ​​a polygon having a reflector as a vertex. FIG. 8 is a diagram illustrating an example of the correspondence between area A obtained by simulation and inclination estimation accuracy. FIG. 9 is a diagram illustrating an example of a reflector position identified by the processing device. FIG. 10 is a diagram illustrating a coordinate system in an experimental environment. FIG. 11 is a diagram illustrating the positions of a reflector and a radar in the experimental environment. FIG. 12 is a distance intensity graph obtained by an experiment. FIG. 13 is a diagram illustrating an example of an estimation result of surface inclination. FIG. 14 is a diagram illustrating the hardware configuration of a computer used in the processing device.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

[0013] (Processing Device) The processing device 1 according to the present disclosure calculates the positions of multiple reflectors R so that the positions of the multiple reflectors R on a predetermined plane P can be identified through measurements using the millimeter-wave radar 111. In the present disclosure, the number of reflectors R installed on the plane P is three or more so that they can form a polygon. Note that in the present disclosure, the millimeter-wave radar 111 may be simply referred to as the radar 111.

[0014] The reflector R, whose position is determined by the processing device 1, is used in a flight control system 100 shown in Fig. 2. The flight control system 100 measures the position of the reflector R using, for example, a millimeter-wave radar 111, and estimates the inclination of a plane P on which a UAV (Unmanned Aerial Vehicle) 110, such as a drone, lands.

[0015] The flight control system 100 measures the three-dimensional positions of three or more reflectors R using a millimeter-wave radar 111 mounted on the UAV 110. The flight control system 100 estimates the center position of the plane P as seen from the millimeter-wave radar 111 using the arrangement position of each reflector relative to the known center position of the plane P, the irradiation direction of the millimeter-wave radar 111, and the measured three-dimensional position of each reflector R.

[0016] At this time, the flight control system 100 may use the measured three-dimensional position of each reflector R to measure the distance between the millimeter-wave radar 111 and each reflector R. Each measured distance is used to estimate the inclination of the plane P as seen from the millimeter-wave radar 111.

[0017] The processing device 1 calculates the position of the reflector R so that the position of the reflector R is appropriately measured by the millimeter wave radar 111. According to the calculation by the processing device 1, the reflector R is embedded in the surface P on which the UAV 110 lands. From the positions of the reflectors R calculated by the processing device 1, the placement positions of the reflectors R relative to the center position of the surface P in the flight control system 100 are identified.

[0018] Here, when appropriately estimating the inclination of the surface P in which the reflector is embedded, the following two viewpoints (1) and (2) can be considered in order to determine the placement of the reflector.

[0019] (1) Any two reflectors R are arranged at an interval greater than the distance from the radar 111 that is equal to or greater than the spatial resolution of the radar 111. If the difference between the distances from the radar 111 of any two reflectors R is smaller than the spatial resolution of the radar 111, the point cloud corresponding to the position of the reflector R obtained by measurement by the radar 111 will be degenerate. As shown in FIG. 3A, erroneous recognition will occur, such as recognizing two reflectors R as one reflector R, and the estimation accuracy of the tilt of the plane P will be significantly reduced.

[0020] 3B, it is necessary to position each of the multiple reflectors R so that the difference in distance between the millimeter-wave radar 111 and each reflector R is equal to or greater than the distance resolution of the millimeter-wave radar 111. This allows the position of each reflector R to be recognized, improving the accuracy of estimating the tilt of the surface P.

[0021] (2) The reflectors R are arranged on the surface P so as to form a polygon with vertices of the reflectors R, the polygon having an area equal to or greater than a predetermined value. As shown by the solid line on the surface P in Figure 4(a), when the reflectors R are arranged near a certain straight line, the accuracy of estimating the rotation angle around the straight line decreases, and the position of the reflector R is not measured correctly. This results in a large difference between the estimated tilt and the true tilt.

[0022] Therefore, as shown by the solid lines on the plane P in Fig. 4(b), it is necessary to arrange the reflectors R so that the area of ​​a polygon on the plane P, with the reflectors R as vertices, becomes large. Here, the area of ​​the polygon is a geometric area.

[0023] Here, the multiple reflectors R must be arranged so that the area of ​​a polygon on the plane P, with the multiple reflectors R as vertices, is equal to or greater than a predetermined threshold. Here, the predetermined threshold is an area that satisfies the accuracy required for the flight control system 100. This reduces the difference between the estimated tilt and the true tilt.

[0024] The processing device 1 according to the present disclosure calculates the position of the reflector R on the plane P so as to satisfy the above requirements (1) and (2), and shares the calculated position of the reflector R with the flight control system 100.

[0025] 1, the processing device 1 includes requirement data 11 and placement data 12, and the function of a calculation unit 21. Each piece of data is stored in a storage device such as a memory 902 or a storage 903. The function is implemented in a CPU 901.

[0026] The requirement data 11 includes data related to the performance required for the flight control system 100, and data necessary for calculating the position of the reflector R. The requirement data 11 is data that specifies, for example, the possible arrangement area of ​​the reflector R, the irradiation position of the radar 111, the distance resolution of the radar 111, the position measurement error of the radar 111, the allowable estimated tilt error of the plane P, and the signal-to-noise ratio of the reflected signal of the reflector R. The requirement data 11 is specified from the system requirements of the flight control system 100.

[0027] The arrangement data 12 is data that specifies the position of each of a plurality of reflectors R arranged on the surface P. When three reflectors R are arranged on the surface P, the arrangement data 12 includes three pieces of position information.

[0028] The calculation unit 21 calculates the positions of the plurality of reflectors R so that the positions of three or more reflectors R on a predetermined plane P can be identified by measurement using the millimeter-wave radar 111. The calculation unit 21 calculates the positions of the reflectors from both the above-mentioned viewpoints (1) and (2).

[0029] With respect to the above aspect (1), the calculation unit 21 calculates the position of each of the multiple reflectors such that the difference in distance between the millimeter-wave radar 111 and each reflector R is equal to or greater than the distance resolution of the millimeter-wave radar 111. The distance between the i-th reflector Ri and the irradiation position of the radar 111 is set to di (0≦i<N, where N is the number of reflectors arranged on the plane P). The calculation unit 21 calculates the position of each reflector R for any two reflectors Ri and Ri+1 such that the difference in distance between the reflector and the irradiation position of the radar 111, specifically the difference between di and di+1, is equal to or greater than the distance resolution of the millimeter-wave radar 111. When three reflectors R are used, the calculation unit 21 repeats the process of calculating the difference in distance between any two reflectors R and the millimeter-wave radar 111 three times, and calculates the position of each reflector R such that each of the three differences is equal to or greater than the distance resolution of the millimeter-wave radar 111.

[0030] When the millimeter-wave radar 111 uses Range-FFT (Fast Fourier Transform), the distance resolution of the millimeter-wave radar is c / 2BW (c: speed of light, BW: bandwidth of the millimeter-wave radar). The calculation unit 21 calculates the position of each reflector R so that the difference in distance between the millimeter-wave radar 111 and each reflector R is c / 2BW or more.

[0031] Regarding the above aspect (2), the calculation unit 21 calculates the positions of the plurality of reflectors R at which the area of ​​a polygon on the plane P, with the plurality of reflectors as vertices, is equal to or greater than a predetermined threshold. The threshold is calculated by the threshold calculation unit 22. The processing of the threshold calculation unit 22 will be described in detail later.

[0032] (Processing Method) A processing method according to the present disclosure will be described with reference to Fig. 5. The processing method shown in Fig. 5 identifies the position of the reflector R using the minimum value dint of the distance interval between the reflectors R and the area A formed by a polygon having the reflector R as a vertex.

[0033] In step S1, the calculation unit 21 acquires requirement data 11. Here, the requirement data 11 includes the possible arrangement area of ​​the reflector R, the irradiation position of the radar 111, the distance resolution of the radar 111, the position measurement error of the radar 111, the allowable estimated tilt error of the plane P, the S / N ratio of the reflected signal of the reflector R, etc.

[0034] In step S2, the calculation unit 21 sets the number N of reflectors R to 3. In order to form a polygon with the reflectors R, at least three reflectors R are required. In subsequent processing, if the positions of three reflectors R that satisfy the requirements cannot be determined, the calculation unit 21 determines the positions of the reflectors R while incrementing the number of reflectors R by one.

[0035] In step S3, the calculation unit 21 calculates the arrangement interval dint of the reflectors R on the surface P to achieve a low false detection rate. The arrangement interval dint is obtained by simulation. For example, the calculation unit 21 calculates the false detection rate for each of a plurality of reflector arrangement intervals and identifies the arrangement interval that achieves the minimum false detection rate.

[0036] In step S4, the calculation unit 21 calculates a threshold Ath of the area A of the polygon formed by the reflector R.

[0037] In step S5, the calculation unit 21 determines whether a reflector arrangement that satisfies the system requirements identified by the requirement data 11 acquired in step S1 is possible. The calculation unit 21 determines whether a reflector arrangement is possible using equation (1). dmax and dmin are the maximum and minimum distances from the radar irradiation position to the reflector arrangement possible area, as defined as shown in Figure 6. The radar irradiation position is the entry position of the UAV 110 in the flight control system 100 in Figure 2.

[0038]

[0039] If the calculation unit 21 determines that the formula (1) is not satisfied, the process returns to step S1, where the calculation unit 21 reconsiders the requirement data 11. If the formula (1) is satisfied, the process proceeds to step S6.

[0040] In step S6, the calculation unit 21 sets the distance distribution of each reflector R. The calculation unit 21 determines the distance at which N reflectors R are arranged from equation (2). This distance di is the distance from the position of the radar 111 to the reflector R. In equation (2), the distance distribution of each reflector R is set so as to satisfy the minimum interval dint determined in step S3. Note that the identifier i of the reflector R is assigned in ascending order in order of proximity to the radar irradiation position.

[0041]

[0042] Once the distance distribution of each reflector R is set according to equation (2), in step S7 the calculation unit 21 determines a combination of placement positions of each reflector R that maximizes the area A. For example, as shown in Fig. 7 , the calculation unit 21 identifies a combination of placement positions that satisfies the distance distribution set in step S6. The calculation unit 21 calculates the area A for each combination and determines the combination that maximizes the area A.

[0043] In step S8, the calculation unit 21 determines whether the area A of the arrangement position determined in step S7 is larger than the threshold value Ath calculated in step S4.

[0044] If the area A does not exceed the threshold value Ath in step S8, the calculation unit 21 determines in step S9 whether or not the search for each distance distribution of each reflector R has been completed for the current number of reflectors. If the search for each distance distribution of each reflector R has not been completed for the current number of reflectors, the process returns to step S6, and the calculation unit 21 repeats the processes of steps S6 to S8 for the distance distribution of each reflector R that has not been searched.

[0045] In step S9, if it is determined that the search for each distance distribution of each reflector R has been completed for the current number of reflectors, the calculation unit 21 determines that, for the current number of reflectors, there is no placement position of a reflector R that satisfies the requirements of the requirement data 11. In step S10, the calculation unit 21 increments the number of reflectors by one and returns to step S3. The calculation unit 21 repeats the processes of steps S3 to S8 for the number of reflectors that has increased by one.

[0046] If the area A exceeds the threshold value Ath in step S8, in step S11, the calculation unit 21 determines the placement positions of each reflector set in step S7 as the positions of the reflectors R that satisfy each requirement in the requirement data 11. The calculation unit 21 outputs the determined positions of each reflector R as placement data 12.

[0047] The content and order of the processing shown in FIG. 5 are merely an example and are not limited to this.

[0048] (Threshold Calculation Unit) The threshold calculation unit 22 calculates a threshold that is referred to when the calculation unit 21 calculates the area of ​​a polygon on the plane P having a plurality of reflectors as vertices.

[0049] The threshold calculation unit 22 calculates a threshold based on the required accuracy. Specifically, the threshold calculation unit 22 generates a plurality of arrangement patterns of a plurality of reflectors R. In order to satisfy the estimation accuracy required in estimating the inclination of the surface P, the calculation unit 21 calculates the area of ​​the polygon and the estimation accuracy in estimating the inclination of the surface for each of the plurality of arrangement patterns, and specifies a correspondence relationship between the calculated area and the estimation accuracy. From the specified correspondence relationship, the calculation unit 21 calculates, as the threshold, the minimum value of the area that satisfies the required estimation accuracy.

[0050] The threshold calculation unit 22 calculates the threshold Ath through simulation.

[0051] The threshold calculation unit 22 first determines input parameters, such as the required tilt estimation accuracy, the radar irradiation position, the possible range for reflector placement, the number N of reflectors to be installed, and the position measurement error of the radar 111. The threshold calculation unit 22 assumes that the position measurement error of the radar 111 follows a normal distribution, and sets variance values ​​for the distance, azimuth angle, and elevation angle.

[0052] Next, the threshold calculation unit 22 calculates the correspondence relationship between the area A and the inclination estimation accuracy through simulation. Specifically, the threshold calculation unit 22 obtains the correspondence relationship between the area A and the inclination estimation accuracy by repeating the following two steps (i) and (ii) a sufficient number of times.

[0053] (i) The threshold calculation unit 22 generates various reflector arrangement patterns using random numbers.

[0054] (ii) The threshold calculation unit 22 performs tilt estimation based on the reflector arrangement obtained in (i) and predetermined input parameters, and calculates the estimation accuracy. Since radar measurement errors follow a normal distribution, the accuracy varies for each trial. The threshold calculation unit 22 calculates the average of the estimation accuracy obtained through multiple trials.

[0055] Figure 8 shows an example of the correspondence relationship between area A and tilt estimation accuracy obtained by simulation. Figure 8(a) shows the correspondence relationship when the number N of reflectors R is changed while the radar position measurement error is kept constant. The larger the number N of reflectors R, the larger the maximum value of area A. However, Figure 8(a) shows that the relationship between geometric area and tilt estimation accuracy does not change significantly with N, but is determined by area A. Figure 8(b) shows the correspondence relationship when the radar position measurement error is changed while the number N of reflectors is kept constant at 4.

[0056] The threshold calculation unit 22 can calculate the required threshold value Ath for the area A from the correspondence relationship between the area A and the tilt estimation accuracy shown in Fig. 8(b) and the required tilt estimation accuracy. Note that Fig. 8(b) shows the correspondence relationship between the area A and the tilt estimation error when N = 4, but the correspondence relationship between the area A and the tilt estimation error may be calculated in advance for N = 3 or any other natural number.

[0057] (Example) Next, an example will be described in which the reflector R is arranged according to the position specified by the processing device 1, and the reflector R is detected by the radar 111 in an experimental environment.

[0058] 9(a) and 9(b) show the positions of the reflector R identified by the processing device 1. Fig. 9(a) shows the radar irradiation position, i.e., the placement position of the reflector R when it is assumed that the intrusion direction of the UAV 110 is diagonal. Fig. 9(b) shows the radar irradiation position, i.e., the placement position of the reflector R when it is assumed that the intrusion direction of the UAV 110 is directly above.

[0059] In Figure 9(a), the system variables are set as follows: the reflector placement area is a circle with a radius of 0.4 m, the radar irradiation position is (x, y, z) = (1 m, 0 m, 1 m), the radar distance resolution is 37.5 mm, the radar position measurement error (distance, azimuth angle, elevation angle) is (10 mm, 1°, 1°), the allowable estimated tilt error is 3°, and the S / N ratio of the reflected signal from the reflector is 10 dB.

[0060] In Figure 9(b), the system variables are set as follows: the reflector placement area is a circle with a radius of 0.48 m, the radar irradiation position is (x, y, z) = (0 m, 0 m, 0.5 m), the radar distance resolution is 37.5 mm, the radar position measurement error (distance, azimuth angle, elevation angle) is (10 mm, 1°, 1°), the allowable estimated tilt error is 3°, and the S / N ratio of the reflected signal from the reflector is 10 dB.

[0061] An example will be described in which the inclination of a plane P on which a reflector R is arranged is estimated by a millimeter-wave radar 111 as shown in Fig. 9. The position of the millimeter-wave radar 111 is (x, y, z) = (1 m, 0 m, 1 m) in the coordinate system of Fig. 10. The irradiation direction of the millimeter-wave radar 111 is fixed so as to face the center of the plane P. The position Si of the reflector R is determined as shown in equation (4) when expressed in polar coordinates shown in equation (3) with N = 4.

[0062]

[0063]

[0064] The position of the reflector R and the position of the radar 111 thus identified are shown in FIG.

[0065] Next, the specifications of the millimeter-wave radar 111 will be described. The millimeter-wave radar 111 is a 79 GHz millimeter-wave FMCW (Frequency-Modulated Continuous-Wave) radar, and uses the 77-81 GHz band. The millimeter-wave radar 111 achieves a ranging resolution of 37.5 mm. The distance resolution is calculated from the speed of light (2 × the used bandwidth). The millimeter-wave radar 111 has three transmitting antennas and four receiving antennas. The azimuth and elevation angles at which the reflector R is located are calculated based on the measurement results of the MIMO (Multi-Input Multi-Output) antennas, and the three-dimensional position is estimated in addition to the distance.

[0066] The millimeter wave radar signal is used for highly accurate position estimation by Root-MUSIC (see Non-Patent Document 9).

[0067] The surface P is realized by a disk-shaped polystyrene foam with a thickness of 3 cm and a radius of 0.5 m. Holes are cut out at the locations where the reflectors R are to be installed. Each reflector R is fitted into the hole and fixed.

[0068] Fig. 12 is a distance intensity graph obtained by performing measurements in the experimental environment shown in Fig. 11 and analyzing the millimeter wave radar 111. Fig. 12 shows that four reflection points are detected near the position of plane P (near 1.4 m), and therefore it can be seen that four reflectors R were detected.

[0069] From this result, the tilt of the plane P is estimated as shown in Fig. 13. Fig. 13 shows that the three-dimensional position of the reflector R is measured.

[0070] The processing device 1 according to the present disclosure can form a plane P that enables highly accurate and reliable tilt estimation even if the position estimation accuracy of the radar 111 is limited. The plane P is used for a port where the UAV 110 lands, etc.

[0071] The processing device 1 is capable of creating a landing port suitable for the use case by taking into account various system requirements such as the direction of entry of the UAV 110, radar performance, and the size of the landing surface.

[0072] This enables the UAV 110 to land on a moving landing surface such as a truck bed, a ship's deck, or an offshore floating port in all weather conditions, including poor visibility conditions such as fog, rain, and nighttime. The processing device 1 can broaden the scope of use of UAVs 110 such as drones in the delivery industry, marine environment observation fields, etc.

[0073] The processing device 1 according to the present disclosure described above is, for example, a general-purpose computer system including a CPU (Central Processing Unit, processor) 901, a memory 902, a storage 903 (HDD: Hard Disk Drive, SSD: Solid State Drive), a communication device 904, an input device 905, and an output device 906. In this computer system, the CPU 901 executes a program loaded on the memory 902, thereby realizing each function of the processing device 1.

[0074] The processing device 1 may be implemented by one computer or by multiple computers, or may be a virtual machine implemented on a computer.

[0075] The program of the processing device 1 can be stored in a computer-readable recording medium such as a HDD, SSD, USB (Universal Serial Bus) memory, CD (Compact Disc), DVD (Digital Versatile Disc), or can be distributed via a network. The computer-readable recording medium is, for example, a non-transitory recording medium.

[0076] The functionality of each element of this disclosure may be implemented using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), general circuitry, and / or combinations thereof, that are programmed using one or more programs stored in one or more memories or otherwise configured to perform the disclosed functions. A processor is considered a circuit or processing circuit because it includes transistors and other circuitry. A processor may also be a programmed processor that executes programs stored in a memory. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or is hardware that is programmed to perform the recited functions. Hardware may be any hardware of this disclosure that is programmed or configured to perform the recited functions.

[0077] The memory stores a computer program including computer instructions. These computer instructions provide the logic and routines that enable the hardware (e.g., circuitry or processing circuitry) to perform the methods of the present disclosure. The computer program can be implemented in a common form as a computer-readable storage medium, a computer program product, a memory device, a recording medium such as a CD-ROM or DVD, and / or memory of an FPGA or ASIC.

[0078] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the present disclosure.

[0079] REFERENCE SIGNS LIST 1 Processing device 11 Requirement data 12 Placement data 21 Calculation unit 22 Threshold calculation unit 100 Flight control system 110 UAV 111 Millimeter wave radar (radar) 901 CPU 902 Memory 903 Storage 904 Communication device 905 Input device 906 Output device P Surface R Reflector

Claims

1. A processing device comprising a calculation unit that calculates the position of each of three or more reflectors on a given surface so that the positions of the reflectors can be identified by measurement using a millimeter-wave radar, wherein the calculation unit calculates the position of each of the reflectors such that the difference in distance between the millimeter-wave radar and each reflector is equal to or greater than the distance resolution of the millimeter-wave radar.

2. The processing device according to claim 1, wherein when the millimeter-wave radar uses Range-FFT, the difference in distance between the millimeter-wave radar and each reflector is equal to or greater than c / 2BW (c: speed of light, BW: bandwidth of the millimeter-wave radar).

3. The processing device according to claim 1, wherein the calculation unit calculates the positions of the plurality of reflectors such that the area of ​​a polygon on the surface having the plurality of reflectors as vertices is equal to or greater than a predetermined threshold value.

4. The processing device according to claim 3, wherein the calculation unit calculates the threshold value from the estimation accuracy required in estimating the inclination of the surface.

5. The processing device according to claim 4, wherein the calculation unit generates a plurality of arrangement patterns of the plurality of reflectors, calculates the area of ​​the polygon and the estimation accuracy in estimating the inclination of the surface for each of the plurality of arrangement patterns, identifies a correspondence between the calculated area and the estimation accuracy, and calculates, from the identified correspondence, the minimum value of the area that satisfies the required estimation accuracy as the threshold value.

6. A processing method in which a computer calculates the position of each of three or more reflectors on a given surface so that the positions of the reflectors can be identified by measurements using a millimeter-wave radar, and the computer calculates the position of each of the reflectors so that the difference in distance between the millimeter-wave radar and each reflector is equal to or greater than the distance resolution of the millimeter-wave radar.

7. A program that causes a computer to function as a calculation unit that calculates the positions of three or more reflectors on a specified surface so that the positions of the reflectors can be identified by measurement using a millimeter-wave radar, wherein the calculation unit calculates the positions of the reflectors such that the difference in distance between the millimeter-wave radar and each reflector is equal to or greater than the distance resolution of the millimeter-wave radar.

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