Altitude calculation method and altitude calculation program for flying object, and flying body with same

Abstract

To provide an altitude calculation method and an altitude calculation program for a flying object that can calculate the accurate altitude without any additional measuring device even in a place where there is no structure as a marker in the circumference or in a place where there is another flying object under the flying object, and the flying object with the same.SOLUTION: The present invention relates to an altitude calculation method for a flying object, and the altitude calculation method includes calculating the altitude of the flying object using information on the horizontal coordinates of the flying object, reception signal intensity of a radio signal and previously acquired altitude calculation supplementary information.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a technique for calculating the altitude of an aircraft. [Background technology]

[0002] In response to recent social issues such as a decline in the working population and decarbonization, there is a demand for diversification and multi-stage development in the field of mobility. In particular, with the development of drone technology, there is an increasing demand for air mobility for logistics and short- and medium-distance travel, and the automation (unmanned) and high-speed operation of aircraft are expected to become essential technologies for sustainable development in the future.

[0003] Accurate identification of the current location is essential for automating flying objects, and various methods are being considered, such as satellite positioning such as GNSS (Global Navigation Satellite System) and pattern matching technology that searches for the corresponding location from images from cameras mounted on flying objects. Many flying objects can also measure the altitude of flying objects using barometers in addition to GNSS positioning. However, because GNSS uses satellites to calculate position, while it can calculate coordinates with high accuracy in the horizontal direction, there is a problem that errors are likely to occur in the vertical coordinates. In addition, the amount of change in air pressure with altitude is not large, making it difficult to measure precise altitude using a barometer.

[0004] In contrast, Patent Document 1 is a background technique in this technical field. Patent Document 1 discloses a technique for capturing images of the surroundings using a camera mounted on an aircraft, and estimating the flight position of the aircraft with high accuracy using landmark structures as references. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-212204 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Document 1, it is possible to estimate an accurate altitude based on an image captured by a camera and using landmark structures as a reference. However, when operating an aircraft in an urban area such as air mobility, it is assumed that the takeoff and landing port will be installed on the rooftop of a building. In this case, if there is no building higher than the takeoff and landing port in the vicinity, there will be no landmark structures for altitude, and therefore the altitude cannot be estimated by pattern matching and an accurate altitude cannot be obtained.

[0007] On the other hand, there is a method of measuring altitude using a laser range finder to measure the distance to the ground. Here, since air mobility may involve the simultaneous operation of many flying objects, it is assumed that multiple flying objects will be waiting above the departure and arrival port during takeoff and landing. In this case, if there is another flying object below the flying object, it will be blocked and the altitude cannot be measured with the laser range finder. In addition, adding equipment for measuring altitude such as a laser range finder will result in a burden in terms of aircraft weight and cost.

[0008] In view of the above problems, the present invention aims to provide an altitude calculation method and an altitude calculation program for an aircraft that can calculate an accurate altitude without additional measuring devices, even in places where there are no landmark structures in the vicinity or where there are other aircraft below the aircraft. [Means for solving the problem]

[0009] One example of the present invention is a method for calculating the altitude of an aircraft, which calculates the altitude of the aircraft using information on the horizontal coordinate of the aircraft, the received signal strength of a radio signal, and altitude calculation auxiliary information obtained in advance. Effect of the Invention

[0010] According to the present invention, it is possible to provide an altitude calculation method and an altitude calculation program for an aircraft, which can calculate an accurate altitude without additional measuring devices even in places where there are no landmark structures in the vicinity or where there are other aircraft below the aircraft, and an aircraft having the same. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a configuration diagram of an altitude calculation system according to a first embodiment. [Diagram 2] FIG. 2 is a hardware configuration diagram of an aircraft in the first embodiment. [Diagram 3] FIG. 2 is a functional configuration diagram of an aircraft in the first embodiment. [Figure 4] FIG. 4 is a diagram showing correspondence information between altitude and received signal strength in the first embodiment. [Diagram 5] 4 is a process flowchart of an altitude calculation unit in the first embodiment. [Figure 6] FIG. 11 is a diagram for explaining a method for calculating the altitude of an aircraft in the second embodiment. [Figure 7] FIG. 11 is a diagram illustrating base station information in the second embodiment. [Figure 8] 13 is a process flowchart of an altitude calculation unit in the second embodiment. [Figure 9] FIG. 11 is a diagram for explaining a method for calculating the altitude of an aircraft in the third embodiment. [Figure 10] FIG. 13 is a diagram showing reception intensity change information in the third embodiment. [Figure 11] 13 is a process flowchart of an altitude calculation unit in the third embodiment. [Figure 12] FIG. 13 is a diagram for explaining a method for calculating the altitude of an aircraft in the fourth embodiment. [Figure 13] FIG. 13 is a diagram showing change amount correspondence information in the fourth embodiment. [Figure 14] 13 is a process flowchart of an altitude calculation unit in the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0013] Fig. 1 is a configuration diagram of an altitude calculation system in this embodiment. In Fig. 1, the altitude calculation system is composed of aircraft 1a, 1b, and 1c (hereinafter collectively referred to as aircraft 1) capable of wireless communication, wireless base stations 2a and 2b (hereinafter collectively referred to as wireless base station 2 or base station 2) that perform wireless communication with the aircraft 1, takeoff and landing ports 3a and 3b (hereinafter collectively referred to as takeoff and landing port 3) where the aircraft 1 takes off and lands, and a control system 4 that controls the aircraft 1.

[0014] Aircraft 1 flies from takeoff and landing ports 3 installed in various locations to a destination carrying luggage, people, etc., and lands at the destination's takeoff and landing port 3 to transport the people and luggage. A control system 4 obtains information on the position, status, destination, etc. of the aircraft 1 within its airspace, and based on that information, formulates instructions for the safe operation of all aircraft 1 within the airspace, and issues these instructions to each aircraft 1 via wireless communication. Each aircraft 1 operates according to instructions from the control system 4, such as movement, waiting, takeoff and landing.

[0015] Fig. 2 is a hardware configuration diagram of an aircraft in this embodiment. In Fig. 2, aircraft 1 has a propulsion device 11 such as a motor and rotor that is an engine for moving the aircraft, a communication device 12 that communicates with the outside such as a control system, a group of sensors 13 that measures the attitude of the aircraft, a storage device 14 that records necessary information, and a control device (computer) 15 that controls each device. The control device 15 is composed of a CPU 21, a RAM 22, and a flash ROM (FROM) 23. In the control device 15, the CPU etc. interprets an operating program and executes various functions by software processing.

[0016] The FROM 23 stores, as processing programs, a flight control program 24 for performing overall control of the aircraft, a position calculation program 25, and an altitude calculation program 26 for calculating the current altitude of the aircraft. These processing programs are loaded into the RAM 22 and executed by the CPU 21. The FROM 23 may be one memory medium as shown in the figure, or may be composed of multiple memory media. Furthermore, it may be a non-volatile memory medium other than a flash ROM.

[0017] The flight control program 24 controls the propulsion device 11 based on measurement data from a group of sensors 13, such as a gyro sensor and an acceleration sensor, to control the attitude of the aircraft. The position calculation program 25 performs a process of calculating the current position of the aircraft using GNSS or the like. The flight control program 24 also performs a process of notifying the control system 4 of the aircraft position information, which is the result of the calculation by the position calculation program 25 and the altitude information calculated by the altitude calculation program 26, and information such as the destination recorded in the storage device 14, using the communication device 12, and receiving instructions from the control system 4. The flight control program 24 also performs processes such as takeoff and landing, waiting in the sky, and movement using the propulsion device 11 according to instructions from the control system 4. The contents of this embodiment can be executed even when the aircraft is operated by a pilot on board the aircraft or a remote pilot who operates the aircraft through wireless communication from a remote location.

[0018] Fig. 3 is a functional configuration diagram of an aircraft in this embodiment. In Fig. 3, the same components as those in Fig. 2 are given the same reference numerals, and their description will be omitted. In Fig. 3, the difference from the hardware configuration diagram in Fig. 2 is that the control device 15 is configured as a flight control unit 16 that performs processing according to a flight control program 24 in Fig. 2, a position calculation unit 17 that performs processing according to a position calculation program 25, and an altitude calculation unit 18 that performs processing according to an altitude calculation program 26.

[0019] Next, the altitude calculation method in this embodiment will be described. In this embodiment, the received signal strength of the wireless signal for communication is measured, and an accurate altitude is estimated by comparing it with a previously measured distribution map of the received signal strength in the relevant airspace. In this embodiment, the altitude of the flying object is calculated at a specific location where the received signal is measured. For example, a location where the position is clearly known, such as above a takeoff and landing port, and where the wireless environment is stable, is set as the altitude calculation location.

[0020] At the altitude calculation location, the received signal strength of the signal from the wireless base station at each altitude is measured in advance, and correspondence information (correspondence table) between altitude and received signal strength is created as altitude calculation auxiliary information. If there are multiple base stations from which reception is possible, these are compiled to create correspondence information. An example of correspondence information between altitude and received signal strength is shown in Figure 4. In Figure 4, base stations A, B, and C are listed as correspondence information 5 between altitude and received signal strength.

[0021] FIG. 5 is a process flow chart of the altitude calculation unit showing the altitude calculation procedure of the flying object in this embodiment. In FIG. 5, when the flying object calculates its own altitude, first, the flying object moves to a predetermined reception signal measurement location using the position calculation unit 22 (step S1). Next, at that location, the received signal strength of the wireless signal from the base station 2 is measured using the communication device 12 (step S2). For example, when LTE (Long Term Evolution) is used as the wireless communication, the received signal strength is determined as the RSSI (Received Signal Strength Indicator) acquired by the receiving device during communication. At this time, in order to improve the measurement accuracy, the same base station may be measured multiple times, and the results may be statistically processed to obtain the received signal strength. After the measurement, it is confirmed whether there is still an unmeasured base station that can be received at the measurement point (step S3), and if there is, the base station is switched to (step S4) to measure the received signal strength. If there is not, necessary statistical processing is performed on each measurement result, and the measurement result is recorded in the storage device 14 for each base station (step S5).

[0022] Next, in step S6, the altitude that best matches the measurement result of the received signal strength is determined by referring to the correspondence information between altitude and received signal strength stored in storage device 14 (step S7). Methods for determining whether the altitude matches include a method of selecting the altitude that minimizes the total absolute error with the received signal strength of each base station, and a method of evaluating the magnitude of the error by weighting base stations with strong received signal strength.

[0023] In this way, according to this embodiment, accurate altitude can be calculated even in a place where there are no landmarks around or where there is another flying object below the flying object. In addition, since wireless equipment is used for communication, accurate altitude can be calculated without any additional measuring equipment. EXAMPLES

[0024] In the first embodiment, the altitude of the flying object is calculated at a specific calculation location. In contrast, in the present embodiment, a method for calculating the altitude of the flying object at an arbitrary location is described. Fig. 6 is a diagram for explaining the altitude calculation method of the flying object in the present embodiment.

[0025] As a premise of this embodiment, the flying object has base station information, including the horizontal coordinates of the wireless base station, the antenna installation height (H1), and the transmission power strength, stored in a storage device as altitude calculation auxiliary information. An example of the base station information is shown in Fig. 7. In Fig. 7, the base station information 6 includes the position coordinates X, Y, Z and the transmission power strength Tx for base stations A, B, and C.

[0026] 6, the horizontal distance (L1) between the aircraft 1 and the wireless base station 2 is calculated using base station information 6 and the aircraft's own position information measured by the aircraft. For example, if the coordinates of the base station 2 are (x1, y1) and the coordinates of the aircraft 1 are (x2, y2), the horizontal distance (L1) can be calculated using the following formula (1).

[0027] L1^2=(x1-x2)^2+(y1-y2)^2 ···(1) Next, the aircraft 1 measures the strength of the signal received from the base station 2 at that position. The signal propagation distance is calculated from the result of this reception power strength measurement and the information on the transmission power strength of the base station 2, and this is set as the straight-line distance (L2) between the base station 2 and the aircraft 1. The amount of attenuation of a wireless signal due to distance can be calculated from the Friis propagation formula. In addition, in urban areas, where there is an obstruction between the base station and the aircraft, the propagation distance can be estimated using a propagation model such as the Walfisch-Ikegami model. From L2 and L1 obtained as above, the relative altitude (H2) between the aircraft 1 and the base station 2 is calculated using the following formula (2).

[0028] H2^2=L2^2-L1^2 (2) From this relative altitude (H2) and the antenna installation height (H1) from the zero altitude position 30 of the base station 2, the altitude (H3) of the aircraft from the zero altitude position 30 is calculated using the following formula (3).

[0029] H3 = H1 + H2 (3) Fig. 8 is a process flow chart of the altitude calculation unit showing the altitude calculation procedure of the aircraft in this embodiment. In Fig. 8, the aircraft first calculates its own position in the position calculation unit 22 (step S21). Next, the aircraft measures the received signal strength of the signal from the wireless base station at that position using the communication device 12 (step S22), and performs and records the necessary statistical processing (step S23). Next, the altitude calculation unit refers to the position information of the base station received from the base station information in the storage device, and calculates the horizontal distance (L1) between the base station and the aircraft using formula (1) (step S24).

[0030] Next, the altitude calculation unit calculates the straight-line distance between the base station and the aircraft from the measured received signal strength and the transmitted signal strength obtained from the base station information (step S25). Next, the altitude calculation unit calculates the relative altitude (H2) between the base station and the aircraft using equation (2) from the horizontal distance (L1) and straight-line distance (L2) between the base station and the aircraft obtained so far (step S26). Then, the altitude calculation unit calculates the altitude (H3) of the aircraft using equation (3) from the relative altitude (H2) and the antenna installation height (H1) of the base station described in the base station information (step S27). Note that the above measurements may be performed for multiple base stations that can receive signals, and the altitude of the aircraft may be calculated by statistical processing of the measurement results.

[0031] In this way, according to this embodiment, in addition to the effect of the first embodiment, it is possible to calculate the altitude of the flying object at any location. EXAMPLES

[0032] In this embodiment, a method for calculating the altitude of an aircraft in an environment where the received signal strength changes greatly will be described. Fig. 9 is a diagram for explaining the method for calculating the altitude of an aircraft in this embodiment.

[0033] As a premise of this embodiment, the flying object has, in a storage device, reception strength change information, which indicates the change altitude (H4) at which the received signal strength from the wireless base station changes and the amount of change, as altitude calculation auxiliary information at the calculation point. An example of reception strength change information is shown in Fig. 10. In Fig. 10, the reception strength change information 7 includes the change altitude at which the received signal strength changes for base stations A, B, and C, and the amount of change.

[0034] 9, when the aircraft 1 reaches the sky above the measurement location, it changes its altitude while receiving a signal from the wireless base station 2. At this time, if the received signal strength at the aircraft 1 changes significantly due to factors such as the presence of an obstruction 31 between the base station 2 and the aircraft 1 blocking visibility, the amount of change is recorded. Based on this amount of change, the reception strength change information 7 for that measurement point is referenced to determine the altitude at which the change occurs, and this is taken as the aircraft's altitude.

[0035] FIG. 11 is a process flow chart of the altitude calculation unit showing the altitude calculation procedure of the flying object in this embodiment. In FIG. 11, the flying object first moves to a reception signal measurement location (step S31). Next, the flying object uses the communication device 12 to measure the reception signal strength of the signal from the base station at that location (step S32). The flying object descends from there (step S33), and measures the reception signal strength again at the position after the descent (step S34). The altitude calculation unit compares the reception signal strength before and after this movement and checks whether it exceeds a predetermined conversion amount (step S35). If it does not exceed it, it further descends using that point as a reference point, and repeats the same measurement and comparison. If the amount of change exceeds the specified value, the altitude calculation unit records the amount of change (step S36), and checks at what altitude that amount of change occurs by referring to the reception intensity change information 7 (step S37). As a result, the altitude calculation unit calculates the altitude of the flying object at that time (step S38). In this embodiment, the altitude of the aircraft is calculated in an environment where the received signal strength changes greatly, and therefore in step S35, it is assumed that the received signal strength exceeds a predetermined conversion amount at some altitude during the aircraft's descent. However, assuming that the change in the received signal strength does not exceed the specified value, in step S35, a process may be performed to disable altitude calculation if the aircraft's altitude falls below a predetermined value.

[0036] Thus, according to this embodiment, in addition to the effects of the first and second embodiments, the accurate altitude of the flying object can be calculated even in an environment where the received signal strength changes greatly. EXAMPLES

[0037] In this embodiment, another method for calculating the altitude of an aircraft will be described. Fig. 12 is a diagram for explaining the method for calculating the altitude of an aircraft in this embodiment.

[0038] As a premise of this embodiment, the flying object calculates the altitude at a specific reception signal measurement location. The flying object also has, in a storage device, correspondence information between the amount of change in the reception signal strength from the wireless base station and the amount of change in the altitude at the measurement location as altitude calculation auxiliary information. An example of the change amount correspondence information is shown in FIG. 13. In FIG. 13, the relationship between the amount of change in the altitude and the amount of change in the reception signal strength is shown as the change amount correspondence information 8 for base stations A, B, and C.

[0039] In this embodiment, the flying object can measure the relative change in altitude using an acceleration sensor or the like. In FIG. 12, when the flying object reaches the sky above the measurement point, it changes its altitude while receiving a signal from the wireless base station. At this time, the flying object also measures the amount of change in altitude. Therefore, the amount of change in the received signal strength when a predefined altitude change is made is recorded. The amount of change in altitude (H5) and the amount of change in the received signal strength are referred to in the change amount correspondence information 8 to calculate the altitude (H6) of the flying object.

[0040] FIG. 14 is a process flow chart of the altitude calculation unit showing the altitude calculation procedure of the flying object in this embodiment. In FIG. 14, the flying object first moves to a position where the received signal can be measured (step S41). Next, the flying object uses the communication device 12 to measure the received signal strength of the signal from the base station at that position (step S42). From there, the aircraft descends by a predefined altitude change amount (H5) (step S43), and measures the received signal strength again at the position after the descent (step S44). The measurement result is recorded in the storage device 14 (step S45). Then, the altitude calculation unit refers to the change amount of the received signal strength before and after this movement with the change amount correspondence information 8 in the storage device 14 (step S46). If there is an altitude change corresponding to that change amount, that altitude is set as the aircraft altitude (H6) (step S47). At this time, the received signal strength may be measured for multiple base stations that can receive the signal, and the altitude may be calculated based on the result. If a change amount suitable for the change amount correspondence information 8 cannot be found in one measurement, it is also possible to change the altitude and measure again.

[0041] Thus, according to this embodiment, the altitude is calculated using the amount of change in altitude as well as the amount of change in received signal strength, so that the altitude can be calculated with higher accuracy than in embodiment 1. In addition, since the altitude can be calculated while descending, there is also an advantage that the calculation can be performed during the landing sequence.

[0042] The above describes an embodiment of the present invention, but the present invention uses existing wireless devices used for communication to calculate altitude, so accurate altitude can be calculated without additional measuring devices. Therefore, resources can be utilized by using existing wireless devices, and the present invention contributes to waste reduction, especially in item 12 of the Sustainable Development Goals (SDGs), which is responsible consumption and production.

[0043] Furthermore, the present invention is not limited to the above-mentioned embodiment, and various modified examples are included. For example, the above-mentioned embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to those having all of the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. [Explanation of symbols]

[0044] 1, 1a, 1b, 1c: aircraft, 2, 2a, 2b: radio base station (base station), 3, 3a, 3b: takeoff and landing port, 4: control system, 5: correspondence information between altitude and received signal strength, 6: base station information, 7: reception strength change information, 8: change amount correspondence information, 11: propulsion device, 12: communication device, 13: sensor group, 14: storage device, 15: control device, 16: flight control unit, 17: position calculation unit, 18: altitude calculation unit, 30: altitude zero position, 31: obstruction

Claims

1. A method for calculating the altitude of an aircraft, comprising: An altitude calculation method comprising the steps of: calculating the altitude of the aircraft using information on the horizontal coordinates of the aircraft, the received signal strength of a radio signal, and altitude calculation auxiliary information obtained in advance.

2. 2. The altitude calculation method according to claim 1, The altitude calculation assistance information is correspondence information between altitude and received signal strength at a specific horizontal coordinate position, Using information on the horizontal coordinate of the aircraft, move the aircraft to the specific horizontal coordinate position; measuring a received signal strength of the wireless signal at the particular horizontal coordinate location; An altitude calculation method comprising the steps of: calculating the altitude of the flying object from the received signal strength at the specific horizontal coordinate position and the correspondence information between the altitude and the received signal strength.

3. 2. The altitude calculation method according to claim 1, The altitude calculation assistance information is information regarding horizontal coordinates and altitude position information and transmission power of a radio base station that can be received by the flying object, performing wireless communication with the wireless base station, and calculating a linear distance between the wireless base station and the aircraft from a received signal strength of the wireless communication and a transmission power of the wireless base station that performed the wireless communication; calculating a horizontal distance between the aircraft and the wireless base station from position information of the horizontal coordinates of the aircraft and the horizontal coordinates of the wireless base station obtained from the position calculation device of the aircraft; calculating an altitude difference between the wireless base station and the aircraft from the straight-line distance and the horizontal distance; An altitude calculation method, comprising the steps of: calculating the altitude of the flying object from the altitude difference and position information of the altitude of the wireless base station;

4. 2. The altitude calculation method according to claim 1, The altitude calculation assistance information is information on a change altitude at which a received signal strength at a specific horizontal coordinate position changes and a correspondence between the change amount and the change altitude, Using information on the horizontal coordinate of the aircraft, move the aircraft to the specific horizontal coordinate position; The altitude calculation method is characterized by measuring the received signal strength of the radio signal in response to a change in altitude of the aircraft at the specific horizontal coordinate position, and when the amount of change in the measured received signal strength exceeds the amount of change in the corresponding information, calculating the altitude of the aircraft from the change in altitude of the corresponding information in response to the amount of change.

5. 2. The altitude calculation method according to claim 1, The altitude calculation auxiliary information is correspondence information indicating a relationship between an amount of change in altitude and an amount of change in received signal strength at a specific horizontal coordinate position, Using information on the horizontal coordinate of the aircraft, move the aircraft to the specific horizontal coordinate position; An altitude calculation method comprising the steps of: measuring the received signal strength of the radio signal in response to a change in altitude of the aircraft at a specific horizontal coordinate position; referencing the correspondence information based on an amount of change in the received signal strength of the radio signal in response to the measured change in altitude; and calculating the altitude of the aircraft from the change in altitude at which the received signal strength changes.

6. An aircraft having a propulsion device for moving, a communication device for communicating with the outside, a memory device, and a control device, The storage device stores altitude calculation auxiliary information previously obtained, The control device controls the propulsion device to move the aircraft, calculates information on the horizontal coordinate of the aircraft while it is moving, measures the received signal strength of a radio signal using the communication device, and calculates the altitude of the aircraft using the information on the horizontal coordinate of the aircraft, the received signal strength of the radio signal, and altitude calculation auxiliary information read from the memory device.

7. 7. The flying object according to claim 6, The altitude calculation assistance information is correspondence information between altitude and received signal strength at a specific horizontal coordinate position, The control device controls the propulsion device to move the aircraft to the specific horizontal coordinate position using the information on the horizontal coordinate of the aircraft; measuring a received signal strength of the wireless signal at the specific horizontal coordinate position using the communication device; The altitude of the flying object is calculated from the received signal strength at the specific horizontal coordinate position and the correspondence information between the altitude and the received signal strength.

8. 7. The flying object according to claim 6, The altitude calculation assistance information is information regarding horizontal coordinates and altitude position information and transmission power of a radio base station that can be received by the flying object, The control device includes: performing wireless communication with the wireless base station using the communication device, and calculating a linear distance between the wireless base station and the aircraft from a received signal strength of the wireless communication and a transmission power of the wireless base station that performed the wireless communication; calculating a horizontal distance between the aircraft and the wireless base station from position information of the horizontal coordinates of the aircraft and the horizontal coordinates of the wireless base station obtained from the position calculation device of the aircraft; calculating an altitude difference between the wireless base station and the aircraft from the straight-line distance and the horizontal distance; An aircraft characterized in that the altitude of the aircraft is calculated from the altitude difference and position information of the altitude of the wireless base station.

9. 7. The flying object according to claim 6, The altitude calculation assistance information is information on a change altitude at which a received signal strength at a specific horizontal coordinate position changes and a correspondence between the change amount and the change altitude, The control device includes: Using information on the horizontal coordinate of the flying object, control the propulsion device to move the flying object to the specific horizontal coordinate position; An aircraft characterized in that, at the specific horizontal coordinate position, the communication device is used to measure the received signal strength of the radio signal relative to a change in the altitude of the aircraft, and when the amount of change in the measured received signal strength exceeds the amount of change in the corresponding information, the altitude of the aircraft is calculated from the change in altitude of the corresponding information relative to the amount of change.

10. 7. The flying object according to claim 6, The altitude calculation auxiliary information is correspondence information indicating a relationship between an amount of change in altitude and an amount of change in received signal strength at a specific horizontal coordinate position, The control device includes: Using information on the horizontal coordinate of the flying object, control the propulsion device to move the flying object to the specific horizontal coordinate position; An aircraft characterized in that, at the specific horizontal coordinate position, the communication device is used to measure the received signal strength of the radio signal in response to changes in the altitude of the aircraft, the correspondence information is referenced based on the amount of change in the received signal strength of the radio signal in response to the measured change in altitude, and the altitude of the aircraft is calculated from the change in altitude at which the received signal strength changes.

11. An altitude calculation program for causing a computer to execute an altitude calculation process for an aircraft, The computer is provided with a storage device that stores altitude calculation auxiliary information, The altitude calculation program is characterized in that it causes the computer to execute a process of calculating the altitude of the aircraft using information on the horizontal coordinates of the aircraft, the received signal strength of a radio signal, and altitude calculation auxiliary information stored in the storage device.

12. The altitude calculation program according to claim 11, The altitude calculation assistance information is correspondence information between altitude and received signal strength at a specific horizontal coordinate position, The altitude calculation program moving the aircraft to the specific horizontal coordinate position using information of the horizontal coordinate of the aircraft; measuring a received signal strength of the wireless signal at the particular horizontal coordinate location; and calculating the altitude of the aircraft from the received signal strength at the specific horizontal coordinate position and the correspondence information between the altitude and the received signal strength.

13. The altitude calculation program according to claim 11, The altitude calculation assistance information is information regarding horizontal coordinates and altitude position information and transmission power of a radio base station that can be received by the flying object, The altitude calculation program performing wireless communication with the wireless base station, and calculating a linear distance between the wireless base station and the aircraft based on a received signal strength of the wireless communication and a transmission power of the wireless base station that performed the wireless communication; calculating a horizontal distance between the aircraft and the wireless base station from position information of the horizontal coordinates of the aircraft and the horizontal coordinates of the wireless base station obtained from a position calculation device of the aircraft; calculating an altitude difference between the wireless base station and the aircraft from the straight-line distance and the horizontal distance; and calculating the altitude of the flying object from the altitude difference and position information of the altitude of the wireless base station.

14. The altitude calculation program according to claim 11, The altitude calculation assistance information is information on a change altitude at which a received signal strength at a specific horizontal coordinate position changes and a correspondence between the change amount and the change altitude, The altitude calculation program moving the aircraft to the specific horizontal coordinate position using information of the horizontal coordinate of the aircraft; measuring the received signal strength of the radio signal in response to a change in altitude of the aircraft at the specific horizontal coordinate position, and, when the amount of change in the measured received signal strength exceeds the amount of change in the corresponding information, calculating the altitude of the aircraft from the change in altitude of the corresponding information in response to the amount of change.

15. The altitude calculation program according to claim 11, The altitude calculation auxiliary information is correspondence information indicating a relationship between an amount of change in altitude and an amount of change in received signal strength at a specific horizontal coordinate position, The altitude calculation program moving the aircraft to the specific horizontal coordinate position using information of the horizontal coordinate of the aircraft; At a specific horizontal coordinate position, the received signal strength of the radio signal is measured with respect to the change in altitude of the flying object, and the measured altitude and referencing the correspondence information based on an amount of change in received signal strength of the wireless signal in response to a change in altitude, and calculating the altitude of the flying object from the change in altitude at which the received signal strength changes.

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