Immunity testing device for unmanned aerial vehicle

Abstract

To solve the problem that there is no established method for testing the immunity of an unmanned aerial vehicle, and because the unmanned aerial vehicle originally flies and moves, it is difficult to perform an immunity test in an actual operation state.SOLUTION: The immunity testing device and the immunity testing method of the present disclosure enable a test in a state close to an actual operation of an unmanned aerial vehicle by using a test environment used for general electronic equipment or the like. A simulation signal is used for performing an immunity test as a simulated flight state equivalent to an actual operation state while the unmanned aerial vehicle stays at a fixed position in a certain space. A GTEM cell can be used as a shield structure for housing the unmanned aerial vehicle. The present disclosure also provides an evaluation configuration for analyzing a part vulnerable to an interference electromagnetic wave and specifying a part that may cause a malfunction in an unmanned aerial vehicle.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an apparatus for testing the electromagnetic immunity of unmanned aerial vehicles. [Background technology]

[0002] An unmanned aerial vehicle (UAV) is a type of aircraft used for aviation, such as airplanes, rotorcraft, gliders, and airships, that cannot carry people due to their structure and can be flown by remote control or automatic piloting. Initially, their uses were limited to military and observation purposes, but with the recent emergence of civilian drones, they have spread to a wide range of industrial fields, including aerial photography, agriculture, inspection, logistics, crime prevention, civil engineering, and construction.

[0003] As unmanned aerial vehicles such as drones become more widely used near human habitations, they will be exposed to a variety of electromagnetic wave environments and be subject to electromagnetic interference. Electromagnetic interference includes natural sources such as lightning strikes and cosmic rays, as well as man-made phenomena emitted from communication devices and other devices that use electromagnetic waves, and even those generated intentionally with malicious intent. If an unmanned aerial vehicle becomes uncontrollable and falls due to electromagnetic interference, it could immediately lead to a serious accident. Therefore, it is important to evaluate the immunity of unmanned aerial vehicles to electromagnetic waves.

[0004] For general electrical and electronic equipment, international standards specify the levels of electromagnetic interference and test methods according to the various radio wave environments and types of electromagnetic interference. The interference level is the magnitude of electromagnetic interference measured using a specified method depending on the type of noise. The equipment being tested must be able to withstand electromagnetic waves that exceed this interference level. Immunity testing does not measure the immunity level of individual equipment, but rather classifies the equipment according to its function and performance, determines the interference level that each equipment group must meet, and judges whether it passes or fails. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] IEC 61000-4-20 Ed. 3.0:2022 (b), Testing and measurement techniques - Emission and immunity tests for transverse electromagnetic (TEM) waveguides Standard Summary of the Invention [Problem to be solved by the invention]

[0006] However, no established method has yet been established for immunity testing of unmanned aircraft, and the unique mobile nature of unmanned aircraft has made it difficult to conduct appropriate tests. Below, we will explain the issues surrounding immunity testing using drones as a representative example of unmanned aircraft.

[0007] FIG. 1 is a block diagram showing the configuration and functions of the electronics of a drone, a typical unmanned aerial vehicle. Drone 10 is powered by battery 15, and a voltage converter 14 supplies the necessary stabilized power supply voltage to each component. Overall control of the drone is performed by a flight controller (FCU: Flight Control Unit) 12. The drone obtains its location information from signals received by antenna 11 from a Global Positioning System (GPS). A remote controller receiver 17 and a telemetry transmitter 16 exchange control information, status information, and the like via antenna 19. FCU 12 drives multiple motors 18 for flight via a speed controller 13.

[0008] Figure 2 is a schematic diagram showing the mechanical configuration and function of a drone. Drone 10 has motors 18-1 to 18-4 fixed to a frame 21 to obtain power for flight. Each block of electronic equipment shown in Figure 1 is mounted on a board 22 in the center of frame 21. In Figure 2, the layout of each block on the board differs from the actual layout, and details such as wiring between each block are omitted.

[0009] In the worst case scenario, an unmanned aerial vehicle such as a drone could crash if struck by lightning, for example. The FCU 12 of the drone 10 described above is equipped with many sensors, which can cause the sensor itself to malfunction or communication errors in the sensor signals to prevent attitude control. Furthermore, various factors, such as a voltage supply interruption due to a malfunction of the voltage converter 14, thermal damage to the drivers of the motors 18-1 to 18-4, or a short circuit in the coil windings, could cause the motors to stop and lead to a crash. Even if a crash does not occur, if GPS signals cannot be received, the drone will become uncontrollable and enter a dangerous state. Evaluating the resistance of unmanned aerial vehicles to electromagnetic waves and conducting immunity tests is extremely important.

[0010] However, immunity test methods for unmanned aircraft are still being developed, and no established ones have been established. Because unmanned aircraft have evolved from military and observation applications, immunity test methods and immunity levels have not been made public. Unmanned aircraft can move anywhere, just like automobiles, and are exposed to a variety of electromagnetic phenomena. However, there are no EMC regulations established for unmanned aircraft, such as those for civilian automobiles, railways, and ships.

[0011] Because unmanned aircraft are inherently mobile and flight-oriented, it is difficult to keep them within a fixed, shielded test environment for immunity testing under actual operating conditions. The inherent mobility of unmanned aircraft makes immunity testing itself a practical challenge. Even if a fixed, shielded space for testing can be prepared, for example, in the case of drones, expensive radio repeaters are required to re-radiate GPS signals into that space. Unmanned aircraft are rapidly expanding into civilian applications, and at the same time, their use in close proximity to living spaces is also increasing. Therefore, establishing an immunity test method for unmanned aircraft was an urgent need.

[0012] The present invention has been made in consideration of such problems, and its purpose is to propose an immunity test method and test device for unmanned aerial vehicles that can utilize the test environment of conventional electronic devices, etc. [Means for solving the problem]

[0013] One embodiment of the present invention is an immunity testing device comprising an electromagnetically shielded structure that houses a target unmanned aerial vehicle inside, a test signal source that generates interfering electromagnetic waves for the unmanned aerial vehicle, a simulated signal transmitter that generates a simulated signal including information for identifying a virtual position of the unmanned aerial vehicle, and a control unit that generates the information, and based on the virtual position, determines whether or not a malfunction occurs due to the interfering electromagnetic waves in a simulated flight state equivalent to the unmanned aerial vehicle being stationary or moving in a predetermined direction and at a predetermined speed. [Effects of the Invention]

[0014] As described above, a novel immunity test device for unmanned aerial vehicles is provided. [Brief explanation of the drawings]

[0015] [Figure 1] This is a block diagram showing the configuration and functions of the side of the electronic equipment of the drone. [Figure 2]This is a schematic diagram showing the configuration and function of the mechanical aspects of the drone. [Figure 3] 1 is a diagram showing the configuration of an immunity test device for an unmanned aerial vehicle according to the present disclosure. [Figure 4] 10A and 10B are diagrams illustrating simulated GPS signals of the immunity test device of the present disclosure. [Figure 5] 3A and 3B are diagrams illustrating state information and control information of the immunity test apparatus of the present disclosure. [Figure 6] 10A and 10B are diagrams showing fault determination results obtained by the immunity test apparatus of the present disclosure. [Figure 7] 1 is a diagram showing the configuration of an immunity test device for parts of an unmanned aerial vehicle. [Figure 8] This is a diagram showing the FCU immunity test equipment from the viewpoint of physical configuration. [Figure 9] FIG. 1 shows the actual immunity test status for an FCU. [Figure 10] This is a diagram comparing immunity tests for the entire drone and parts of it. [Figure 11] Another diagram comparing immunity testing of the whole drone and parts. [Figure 12] This is a diagram showing the electrical signals observed during the ESC immunity test. [Figure 13] FIG. 10 is another diagram of the electrical signals observed during the immunity test of the ESC. DETAILED DESCRIPTION OF THE INVENTION

[0016] The immunity test device and test method disclosed herein utilize a test environment commonly used for general electronic devices, enabling testing of unmanned aerial vehicles under conditions close to their actual operation. A simulated signal is used to conduct immunity testing of the unmanned aerial vehicle in a simulated flight state equivalent to its actual operating state. For example, in the case of a drone, a simulated GPS signal is used. A Gigahertz TEM cell (GTEM cell) can be used as the immunity test environment. An evaluation configuration is also proposed for analyzing areas of the unmanned aerial vehicle that are vulnerable to electromagnetic interference and identifying areas that may cause malfunctions.

[0017] [Immunity test equipment] FIG. 3 illustrates the configuration of an unmanned aerial vehicle immunity test apparatus according to the present disclosure. The immunity test apparatus 100 comprises a GTEM cell 101 housing the unmanned aerial vehicle (UAV) to be tested and a test control and monitor unit 105. The GTEM cell 101, as defined in, for example, Non-Patent Document 1, generates electromagnetic waves internally and is entirely shielded. The vertical cross section of the GTEM cell has a tapered shape, with a coaxial connector attached to the tip of the taper. The test signal 121, which is an interfering electromagnetic wave, is emitted from a septum 103, a flat conductor in the center. The opposite end of the tapered tip is unconstricted and terminated by a terminator 102 and a radio wave absorber (not shown). Because the GTEM cell 101 is an electromagnetically shielded structure, no additional anechoic chamber or other device is required for immunity testing.

[0018] A UAV 10 to be tested is placed inside the GTEM cell 101, and the following description will use a drone 10 as an example of the UAV. The drone 10 is installed at a predetermined position (height range x to y from the bottom) relative to the septum 103 as defined in Non-Patent Document 1.

[0019] The GTEM cell 101 can be replaced with another shielded structure, and the drone 10 can be placed inside this structure, using a means for emitting test electromagnetic waves such as an antenna. Specifically, as in vehicle immunity testing, a stripline or antenna can be placed inside an anechoic chamber to radiate test electromagnetic waves to the drone.

[0020] In addition to receiving a test signal 121 via a coaxial cable, the inside and outside of the GTEM cell 101 are coupled via antennas 116 and 117. A simulated GPS signal 118 (described below) is sent to the drone 10 via antenna 116, and a signal 119 containing control and status information is sent to and received from the drone 10 via antenna 117.

[0021] The test control and monitoring unit 105 includes a test signal generator 111 that generates a test signal 121 and a high-frequency amplifier 110 that amplifies the test signal to a predetermined level. The test signal control unit 112 controls the test signal generator 111 and the high-frequency amplifier 110 and monitors their status. The simulated GPS signal control unit 113 controls the simulated GPS signal transmitter 114 and the drone control transceiver 115. Although the test signal control unit 112 and the simulated GPS signal control unit 113 are shown as separate units in FIG. 3, they may also be integrated into a single control unit. Both control units can be implemented by a computer including a processor and may also include an input device and a display device.

[0022] [Simulated GPS signal] The immunity test device 100 of the present disclosure generates simulated GPS signals to set the drone 10 in simulated flight conditions equivalent to real flight conditions, allowing the drone to remain within a storable shielded structure. When the propellers (rotating wings) 23 of a drone such as that shown in FIG. 2 are removed, the drone remains stationary and does not move. Within the limited space of the GTEM cell 101 in FIG. 3, the motors can operate in accordance with the simulated flight conditions based on position information obtained from the simulated GPS signals and control information obtained from the control transceiver 115. The simulated GPS signals that enable drone immunity testing are further described below.

[0023] FIG. 4 is a diagram illustrating simulated GPS signals in the immunity test apparatus of the present disclosure. (a) of FIG. 4 is a schematic diagram of an actual GPS signal received by a drone. A GPS device 303 receives GPS signals 301a-1, 301b-1, and 301c-1 from three satellites 300a to 300c, respectively. Each satellite transmits a GPS signal including time information synchronized with terrestrial time. The GPS device uses the time information from three or more GPS signals from different satellites to determine location information 302-1 based on the time difference between the time information, and can identify the location of the GPS device on the ground.

[0024] If the GPS device 303 moves a certain distance in a certain direction, new location information 302-2 can be obtained at the new location, updated from GPS signals 301a-2, 301b-2, and 301c-2. If the updated location information 302-2 is the same as the previous location information 302-1, the GPS device is determined to be stationary. A stationary state includes a state in which the GPS device is hovering in the sky or landed on the ground. The principle of determining location using GPS signals can be to use time or the difference in time information as long as three or more signals containing synchronized time information from different transmission sources are obtained. Furthermore, this method can be used to determine the location of unmanned aerial vehicles not only in GPS systems but also in systems using other similar satellite signals and systems using radio waves from ground-based transmission facilities.

[0025] The GPS device recognizes its moving state based on GPS signals 301a-1, 301b-1, and 301c-1 when deriving the above-mentioned location information 302-1, and GPS signals 301a-2, 301b-2, and 301c-2 when deriving location information 302-2. Therefore, if the GPS device can receive these GPS signals continuously or intermittently, it is in a state equivalent to being moving.

[0026] FIG. 4(b) shows the immunity test apparatus 100 of the present disclosure transmitting a simulated GPS signal 118 into the GTEM cell from the simulated GPS signal transmitter 114. The drone 10 under test can receive the simulated GPS signal 118 via the GPS antenna 11, thereby achieving a simulated flight condition. The baseband signal of the simulated GPS signal 118 is generated by the simulated GPS signal control unit 113. The simulated GPS signal control unit 113 creates a baseband signal structure for the GPS signal, including synchronized time information. The simulated GPS transmitter generates three wireless GPS signals with a carrier frequency of a predetermined frequency for the baseband signal, combines them, and transmits them from the antenna 116. The target drone 10 within the GTEM cell receives the simulated GPS signal 118 with its propellers removed, creating a simulated flight condition equivalent to that of a real flight, enabling an immunity test to be performed under conditions identical to the actual flight environment. The simulated flight state includes a state equivalent to moving in a predetermined direction at a predetermined speed, or a state equivalent to stopping at a predetermined position. A stopping state corresponds to, for example, a state in which the drone is hovering.

[0027] The simulated GPS signal 118 described above is a simulated signal that, when received, includes information for identifying the virtual location of the drone 10 under test. The drone 10 determines its current virtual location based on the simulated signal, and can achieve a simulated flight or stationary state based on this virtual location and control information from a remote control transmitter, which will be described later.

[0028] The simulated GPS signal, which allows the target drone to virtually recognize whether it is moving or stationary, is preferably continuously updated with time information, just like a real GPS signal. It should be updated at intervals shorter than the update time of the drone's position information, according to the position, speed, direction, etc. set for the target drone.

[0029] GPS signals are used to determine positioning using signals from three or more different satellites. Therefore, the simulated signals include three or more signals each containing time information synchronized with each other, and the virtual position of the drone under test is determined based on the time difference between the time information of the three or more signals. Examples of unmanned aerial vehicles that can be tested using the immunity test apparatus 100 of the present disclosure include drones.

[0030] To conduct an immunity test, a test signal 121 of a predetermined level must be applied to the target drone 10 to determine whether a malfunction or failure has occurred. This determination can be made by receiving status information generated in the drone 10 (described later) with a telemetry receiver and monitoring it in the simulated GPS signal control unit 113.

[0031] FIG. 5 is a diagram illustrating the transmission and reception of status information and control information in the immunity test apparatus of the present disclosure. As shown in FIG. 1, the target drone 10 transmits downlink status information 122 generated by the drone from the telemetry transmitter 16. The telemetry receiver 115a of the test control and monitor unit 105, which is connected to the telemetry transmitter 16, receives the downlink status information 122. In addition, to control the movement and stopping of the drone, the remote control transmitter (RC transmitter) 115b of the test control and monitor unit 105 transmits uplink control information 123 to the drone under test. The RC receiver 17 of the drone 10, which is connected to the RC transmitter 115b, receives the uplink control information 123. By transmitting and receiving the downlink status information 122 and the uplink control information 123, any malfunctions or failures occurring in the drone can be identified.

[0032] In this way, in the immunity test device 100, the simulated GPS signal control unit 113 can receive downstream status information 122, i.e., status information of the unmanned aerial vehicle, using the telemetry receiver 115a, and transmit upstream control information 123, i.e., control information for the unmanned aerial vehicle, from the RC transmitter 115b.

[0033] From the standpoint of immunity testing, the control information for the unmanned aerial vehicle is control information for setting the unmanned aerial vehicle to be tested in a stopped state or a simulated flight state. More specifically, when the drone is stopped, the control information includes information on the stopping position. When the drone is set in a simulated flight state, the control information includes information on the target position and the speed of movement.

[0034] The unmanned aerial vehicle status information includes information on the current location related to the flight status, information on the movement speed, information on the movement direction, information on the flight altitude, etc. It also includes information related to the obstacle class described below. Note that the above-mentioned current location information during the test is obtained based on the simulated GPS signal generated by the simulated GPS signal control unit 113.

[0035] In the following description, the drone under test is assumed to be set in a simulated flight state by control information from the RC transmitter 115b. However, if the drone can operate with an autopilot program, the drone can autonomously maintain the simulated flight state by simply receiving the simulated GPS signal 118 and activating the autopilot program.

[0036] Table 1 below defines fault classes for malfunctions and abnormal behavior that may occur during drone immunity testing. Fault Class 1 occurs when one of the four motors experiences a phenomenon known as "lost synchronization." This phenomenon, described in detail below, causes the motor control pulse signal and motor rotation to become out of sync, resulting in abnormal noise from the out-of-synchronization motor. Fault Class 2 is a GPS or inertial measurement unit (IMU) error, output as fault information from the FCU12 shown in Figure 2. Examples include errors in which the received GPS signal is lost, making the current position unknown, or errors in attitude control that cause the drone to tilt left or right instead of maintaining a horizontal position. Fault Class 3 indicates that at least one of the multiple motors has stopped, making normal flight impossible and resulting in a serious malfunction that could lead to a crash. For fault Classes 1 and 3, the motor status can be visually observed through a window inside the GTEM cell or by using a camera installed inside. TIFF2025173813000002.tif31148 [Example]

[0037] The following describes a more specific example of the configuration of the immunity test device 100 shown in Fig. 3. The drone to be tested was configured using the following available products for each block shown in Fig. 2. TIFF2025173813000003.tif52156 A software radio (Hack RF One) was used to generate the simulated GPS signal. The software radio corresponds to the simulated GPS signal transmitter 114 of the immunity test equipment 100 in Fig. 3. The simulated GPS signal 118 was generated by modulating the baseband signal generated by the simulated GPS signal control unit 113 with the simulated GPS signal transmitter 114.

[0038] To obtain the status information 122 of the drone 10 under test, we used a telemetry device using the 2.45 GHz band and a full-featured ground station application (Mission Planner) for the open source autopilot project, which corresponds to the telemetry transmitter 16 of the drone 10 and the telemetry receiver 115a of the test device.

[0039] The following three types of modulation methods were adopted for a frequency sweep RF signal as the test signal 121, which is an electromagnetic interference wave for evaluating immunity resistance. (1) 1 kHz, 80% modulation AM wave (e.g., as specified in IEC 61000-4-39) (2) Pulse modulated wave (repetition period 20 ms, pulse width 2 ms) (3) Pulse modulated wave (repetition period 2 ms, pulse width 1 ms) The test signal 121 with the above modulation was changed in 0.1 MHz steps between 0.1 MHz and 80 MHz, and in 1 MHz steps between 0.1 MHz and 80 MHz. The dwell time at each frequency was 3 seconds. The electric field strength at the drone's installation position inside the GTEM cell during the test was 100 V / m, which is the maximum electric field strength of the test equipment.

[0040] Figure 6 shows an example of fault class determination results using the immunity test device disclosed herein. The horizontal axis shows the frequency of the test signal, and the vertical axis shows the fault class that was confirmed to have occurred. Each plot point indicates that a fault of that class occurred in the drone. Faults were detected at the plot points of test signal 1 (circle), test signal 2 (pulse width 2 ms) (triangle), and test signal 2 (pulse width 1 ms) (square). A motor stop of fault class 3 was also confirmed near 200 MHz. Errors in the GPS and inertial measurement unit of fault class 2 were also confirmed across a wide range of frequencies.

[0041] The immunity test equipment 100 shown in Figure 6 utilizes a GTEM cell 101, an existing test environment similar to that used for general electronic devices, to perform immunity testing on drones while they remain stationary. This simulated flight state of the drone under test is equivalent to an unmanned aerial vehicle stationary or moving in a specified direction and at a specified speed, allowing for drone immunity testing to be performed under conditions similar to actual operating conditions. However, immunity testing can be performed on drones set in a simulated flight state using simulated GPS signals in any shielded environment or shielded structure that can accommodate the drone under test. The configuration is not limited to the GTEM cell shown in Figure 3. The GTEM cell 101 in Figure 3 can be replaced with a shielded room (anechoic chamber), and the test signal can be transmitted using a single antenna. Antennas such as striplines, biconical antennas, and log-periodic antennas, which are commonly used in vehicle immunity testing, can be used.

[0042] Therefore, the immunity testing device disclosed herein comprises an electromagnetically shielded structure 101 that houses the target unmanned aerial vehicle 10 inside, a test signal source 111 that generates interfering electromagnetic waves for the unmanned aerial vehicle, a simulated signal transmitter 114 that generates a simulated signal including information for identifying the virtual position of the unmanned aerial vehicle, and a control unit 113 that generates the information, and can be implemented to determine whether or not a malfunction caused by the interfering electromagnetic waves occurs based on the virtual position in a simulated flight state equivalent to the unmanned aerial vehicle being stationary or moving in a predetermined direction and at a predetermined speed.

[0043] The immunity test for unmanned aerial vehicles disclosed herein is characterized by providing the target unmanned aerial vehicle with simulated signals that can derive virtual position information similar to that obtained in actual flight conditions, placing the unmanned aerial vehicle in a "simulated flight state." While the immunity test device 100 in FIG. 3 was described above using an example of a drone that operates using GPS, it is also acceptable for the unmanned aerial vehicle to operate using other satellite positioning systems. The unmanned aerial vehicle to be tested may be one that uses radio waves from a terrestrial base station (not a satellite) and can identify its position based on the time information contained in the radio waves.

[0044] As shown in Figure 6, the immunity test device 100 in Figure 3 can perform some kind of pass / fail judgment on whether abnormal operation occurs for a drone set in a simulated flight state using a simulated GPS signal. Although the immunity test device in Figure 3 can perform immunity testing on the entire drone, it cannot determine which parts of the drone are vulnerable. Therefore, we next propose a test device that can identify parts of an unmanned aerial vehicle that have immunity vulnerabilities.

[0045] [Immunity test equipment for unmanned aerial vehicles] FIG. 7 is a diagram showing the configuration of an immunity test device for parts of an unmanned aerial vehicle. In contrast to the test device 100 for testing the entire unmanned aerial vehicle using a GTEM cell shown in FIG. 3, in the test device 200 of FIG. 7, all elements are housed in an anechoic chamber 206. FIG. 7 also uses a drone 10 as an example of the unmanned aerial vehicle. Part 10-1 (EUT: Equipment Under Test) of the drone 10 for which immunity resistance is to be evaluated is housed in a TEM cell 201 via extension wiring 204. In this example, the part 10-1 of the drone to be tested is the FCU 12 of the drone shown in FIG. 2.

[0046] The TEM (Transverse Electromagnetic) cell has a structure in which a coaxial cable is expanded and the central conductor is a septum 203. Both ends of the TEM cell 201 are tapered, and a coaxial connector is attached to the end of each. A disturbance electromagnetic wave test signal 121 is input from one end of the coaxial cable, and the other end is terminated by a terminator 202. The entire cell is shielded, and the electromagnetic field generated within the cell is confined within the cell and radiated only to the FCU 12.

[0047] The main body of the drone, excluding the FCU 12, is located outside the TEM cell 201 and includes a test control and monitor unit 205 similar to that shown in Fig. 3. A simulated GPS signal 118 is provided to the main body of the drone 10 from an antenna 116. The configurations of the test signal generator 111, test signal control unit 112, simulated GPS signal control unit 113, simulated GPS signal transmitter 114, and control transceiver 115 are the same as those of the immunity test apparatus 100 in Fig. 3.

[0048] FIG. 8 is a diagram illustrating a drone's immunity test equipment for FCUs from the perspective of physical configuration. The immunity test equipment of FIG. 7 illustrates a state in which an immunity test is performed on the FCU 12, which is a part of the drone. The FCU 12, housed in the TEM cell, is connected to the main body of the drone 10 via an extension wiring 204, and is functionally capable of normal operation. Although FIG. 7 illustrates the extension wiring 204 as a single wire, it may be multiple wires. Within the TEM cell 201, a test signal 121 can be emitted only to the FCU 12, which is the part of the drone being tested. The drone 10 is set in a simulated flight state by a simulated GPS signal 118 from a simulated GPS signal control unit 113 and a simulated GPS signal transmitter 114. By selectively applying the test signal 121 only to the target FCU 12 within the TEM cell, immunity testing can be performed on the drone in a state similar to the actual operating environment. The target drone 10 in the radio wave anechoic chamber 206 receives a simulated GPS signal 118 with its propellers removed, and remains stationary in a simulated flight state equivalent to flying in real life.

[0049] Figure 9 shows the actual immunity test state for the FCU. On the left side of the photo, a window is open so that the inside of the TEM cell can be seen, revealing the FCU. During actual testing, the window is closed. On the right side of the TEM cell, a drone is shown with each block except the FCU mounted on a frame. In the drone block diagram shown in Figure 2, all parts other than antennas 11 and 19 can be placed within the TEM cell, separated from the drone body, by extension wiring 204 or extension transmission lines. This makes it possible to individually and selectively evaluate the immunity resistance of each part (block) inside the drone.

[0050] The immunity test equipment for the unmanned aerial vehicle parts shown in Figure 7 must be entirely performed inside the anechoic chamber 206. This is because the simulated GPS signal 118 from the simulated GPS signal transmitter 114 will cause malfunctions in drones other than the one being tested. [Example]

[0051] 8 illustrates an example in which immunity testing was performed on only the FCU of a drone using immunity testing equipment 200 for parts of an unmanned aerial vehicle. Similarly, testing can also be performed on other parts of the drone, such as the speed controller (ESC) or the voltage converter (BEC). Therefore, the results of the immunity test on the entire drone using the GTEM cell in FIG. 3 were compared with the test results of each part using the TEM cell in FIG. 7.

[0052] Figure 10 compares immunity tests of a drone as a whole and at individual parts. The horizontal axis shows the frequency of the test signal, and the vertical axis shows the three fault classes. The AM-modulated wave described above was used as the test signal, and the graph shows the results of a drone as a whole test using the GTEM cell in Figure 3 and a test of three drone parts using the TEM cell in Figure 7. The circle plot indicates a drone as a whole (UAV) test using the GTEM cell. For the TEM cell tests, the triangle plot indicates a part test on the FCU, the square plot indicates a part test on the ESC, and the black plot indicates a part test on the voltage converter (BEC).

[0053] Comparing the UAV plot ◯ with the BEC plot ● reveals that malfunctions of fault class 1 and fault class 3 have occurred at the same frequency, and it can be inferred that the cause of these malfunctions is the BEC. Furthermore, comparing the UAV plot ◯ with the FCU plot △ reveals that a malfunction of fault class 2 has occurred, and it can be inferred that the cause of the malfunction is the FCU.

[0054] Figure 11 is another graph comparing immunity tests of a drone as a whole and at individual parts. The horizontal axis shows the frequency of the test signal, and the vertical axis shows the three fault classes. The test signal uses the pulse-modulated wave described above. The graph shows the results of a drone as a whole test using the GTEM cell in Figure 3 and a drone's three parts test using the TEM cell in Figure 7. The circle plot indicates a drone as a whole (UAV) test using the GTEM cell. For the TEM cell test, the triangle plot indicates a part test for the FCU, the square plot indicates a part test for the ESC, and the black plot indicates a part test for the BEC.

[0055] Comparing the UAV plot ◯ and the ESC plot □, it is clear that a fault class 1 malfunction occurred at a similar frequency, and it can be inferred that the cause of fault class 1 is the ESC. Fault class 2 occurred at the UAV plot ◯ and the FCU plot △ at the same frequency, and it can be inferred that the cause of the fault is the FCU. Fault class 3 occurred at the UAV plot ◯ and the BEC plot ● at the same frequency, and it can be inferred that the cause of the fault is the BEC.

[0056] Figures 10 and 11 show a clear correspondence between the occurrence of faults during the overall drone test using the GTEM cell and the occurrence of faults in parts of the drone using the TEM cell. In other words, it is clear that the parts that cause faults in the drone can be identified using the immunity test equipment 200 using the TEM cell shown in Figure 7. Figures 10 and 11 show that fault class 1, which indicates a motor step-out, has occurred, and a fault in the ESC, shown by the square plot, has also been confirmed. Therefore, we observed the electrical signals around ESC 13 when the ESC was tested using the immunity test equipment 200 using the TEM cell shown in Figure 7.

[0057] Figure 12 shows electrical signals observed during an ESC immunity test. In the test equipment configuration shown in Figure 8, only the ESC 13 was placed inside the TEM cell via the extension cable 204. In this state, differential voltage probes were connected to two locations within the drone: between the FCU 12 and ESC 13 (waveform A: ESC-FCU) and between the ESC 13 and the motor (waveform B: ESC-motor). Figure 12 shows the results of an AM-modulated test signal, with two overlapping waveforms observed for a single event. Waveform B between the ESC 13 and the motor shows the PWM signal used to drive the motor, and the motor completely stopped in 0.46 s. After the motor stopped, waveform B between the ESC 13 and the motor became very weak, revealing the amplitude waveform of the combined AM-modulated wave as waveform A. It appears that high-level electromagnetic interference was irradiated onto the ESC 13, which controls the motor speed, causing a Class 3 motor failure, which stopped the motor.

[0058] Figure 13 is another diagram showing electrical signals observed during an ESC immunity test. As in Figure 12, only the ESC 13 was placed inside the TEM cell via the extension wiring 204. In this state, signals appearing at two locations within the drone were measured: between the FCU 12 and ESC 13 (waveform A: ESC-FCU) and between the ESC 13 and the motor (waveform B: ESC-motor). Figure 13 shows the results when a pulse-modulated wave was used as the test signal. It shows a repetitive phenomenon with a shorter period than the observation time in Figure 12. Waveform B between the ESC 13 and the motor reveals a PWM signal (period: 2 msec) for driving the motor. Waveform A between the FCU 12 and ESC 13 also reveals the original PWM signal. Waveform B shows an irregular noise waveform labeled "out of step." This noise waveform indicates an abnormality in the motor's rotation, resulting in a loss of step corresponding to fault class 1. It is believed that the electromagnetic interference pulses are causing irregular abnormalities in the motor's rotation.

[0059] As shown in Figures 12 and 13, the immunity test apparatus 200 for the parts of the unmanned aerial vehicle shown in Figure 7 made it possible to identify the part causing the fault and also observed the abnormal signal waveform corresponding to the fault. With the immunity test apparatus 200 in Figure 7, a simulated signal is applied to the target unmanned aerial vehicle in a normal anechoic chamber, placing it in a "simulated flight state," making it possible to test the immunity resistance of specific parts of the unmanned aerial vehicle.

[0060] The immunity test equipment disclosed herein can conduct immunity tests on unmanned aircraft while the aircraft remains stationary at a fixed position in a fixed space, under conditions nearly equivalent to flight conditions in a real operating environment. Immunity tests on unmanned aircraft can be conducted using existing simple equipment configurations, such as a GTEM cell or a combination of a regular anechoic chamber and a TEM cell, and do not require repeater equipment for positioning signals such as GPS signals. [Industrial Applicability]

[0061] The present invention can be used for immunity testing of unmanned aerial vehicles. [Explanation of symbols]

[0062] 10. Drone 11 GPS antenna 12 Flight Controller (FCU) 13 Speed ​​controller (ESC) 18, 18-1 to 18-4 motor 100, 200 Immunity Test Equipment 101 GTEM cells 103, 203 septum 111 Test Signal Generator 113 Simulated GPS signal control unit 114 Simulated GPS signal transmitter 115 Control transmitter / receiver 201 TEM Cell

Claims

1. An immunity test apparatus comprising: an electromagnetically shielded structure for housing the target unmanned aerial vehicle therein; a test signal source that generates electromagnetic interference waves for the unmanned aerial vehicle; a simulated signal transmitter that generates a simulated signal including information for identifying a virtual location of the unmanned aerial vehicle; a control unit that generates the information; Equipped with Based on the virtual position, it is determined whether or not a fault occurs due to the interfering electromagnetic waves in a simulated flight state equivalent to the unmanned aerial vehicle being stationary or moving in a predetermined direction and at a predetermined speed. Test equipment.

2. The test device of claim 1 , wherein the control unit is further configured to transmit control information for setting the unmanned aerial vehicle to the stopped state or the simulated flight state and to receive status information of the unmanned aerial vehicle.

3. 2. The test apparatus according to claim 1, wherein the simulation signal includes three or more signals each containing time information synchronized with each other, and the virtual position is determined based on a time difference between the time information of the three or more signals.

4. 2. The test apparatus of claim 1, wherein the simulated signal corresponds to a signal obtained by combining radio waves from a transmission source including a satellite or a base station.

5. The test device according to claim 1 , wherein the unmanned aerial vehicle is a drone, and the simulated signal corresponds to a signal obtained by combining positioning signals from different satellites.

6. 2. The test device of claim 1, wherein the structure is a GTEM cell, and the simulated signal is applied to the unmanned aerial vehicle disposed inside the GTEM cell.

7. The test device of claim 1, wherein the structure is an anechoic chamber, a portion of the unmanned aerial vehicle is housed inside a TEM cell, and another portion of the unmanned aerial vehicle is housed in the anechoic chamber, and the simulated signal is applied to the other portion.

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