Rollover risk detection method, rollover risk detection device, flying object, and program

Abstract

A rollover risk detection device (100) is provided with a first attitude angle information acquisition unit (101), a second attitude angle calculation unit (102), an attitude variation calculation unit (103), and a rollover risk detection unit (104). A first attitude angle information acquisition unit (101) acquires first attitude angle information relating to a first attitude angle, which is an attitude angle of a probe (1) based on an inertial system. A second attitude angle calculation unit (102) calculates a second attitude angle relating to the attitude angle of the probe (1) with respect to the gravitational acceleration direction on the basis of the attitude angle information, the gravitational acceleration direction of the celestial body with respect to the inertial system, and the shape information of the probe (1). A posture change calculation unit (103) calculates the posture change of the probe (1) on the basis of the second posture angle at the current time and the second posture angle at the starting point time before the current time. The rollover risk detection unit (104) detects the rollover risk when the probe (1) lands on the celestial body on the basis of the posture change and the positional relationship between the leg tip of the leg (20) that contacts the celestial body and the center of gravity of the probe (1).

Description

Technical Field

[0001] The present disclosure relates to a rollover risk detection method, a rollover risk detection device, a flying object, and a program. Background Art

[0002] Technologies for detecting the tipping risk of a flying object during landing are known. For example, Patent Document 1 discloses the following technology: When a probe, a type of flying object, lands on the surface of a celestial body, the probe's attitude angle relative to the ground is detected. Based on the detected attitude angle, whether there is a tipping risk is determined. If there is a tipping risk, the probe's attitude is controlled by jets.

[0003] Prior art literature

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-17086 Summary of the Invention

[0005] The technology described in Patent Document 1 does not account for celestial gravity, leading to the potential for inaccurate rollover risk detection. For example, if the landing surface is inclined, gravity also affects the aircraft in the horizontal direction relative to the ground, exerting forces on the aircraft in this horizontal direction. However, the technology described in Patent Document 1 does not account for this force, leading to the potential for inaccurate rollover risk detection.

[0006] The present disclosure aims to provide a rollover risk detection method, a rollover risk detection device, a flying object, and a program that can detect the rollover risk of a flying object during landing by taking into account the gravity of a celestial body.

[0007] In order to achieve the above-mentioned purpose, the rollover risk detection method involved in the present disclosure is a rollover risk detection method for detecting the rollover risk of a flying object with landing legs when landing on a celestial body, wherein first posture angle information related to a first posture angle as a posture angle of the flying object based on an inertial system is obtained, and based on the posture angle information, the direction of gravitational acceleration of the celestial body relative to the inertial system, and information on the shape of the flying object, a second posture angle as the posture angle of the flying object relative to the gravitational acceleration direction is calculated, and based on the second posture angle at the current moment and the second posture angle at the starting moment before the current moment, the posture change of the flying object is calculated, and based on the posture change and the positional relationship between the leg end of the leg contacting the celestial body and the center of gravity of the flying object, the rollover risk of the flying object when landing on the celestial body is detected.

[0008] According to the present disclosure, it is possible to detect the rollover risk of a flying object during landing by taking into account the gravity of a celestial body. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a diagram schematically showing a probe according to an embodiment of the present disclosure.

[0010] Figure 2 This is a block diagram showing the functional structure of a detector according to an embodiment of the present disclosure.

[0011] Figure 3 This is a diagram showing an example of posture changes of the probe during landing according to an embodiment of the present disclosure.

[0012] Figure 4 This is a diagram showing an example of the rotation of the probe during landing according to the embodiment of the present disclosure.

[0013] Figure 5 This is a diagram showing an example of the rotation of the probe during landing according to the embodiment of the present disclosure.

[0014] Figure 6 This is a diagram showing an example of a situation in which, when the probe according to the embodiment of the present disclosure lands, the leg tip that touches the ground is positioned in the direction of gravitational acceleration with reference to the center of gravity of the probe.

[0015] Figure 7 This is a diagram showing an example of the hardware configuration of the rollover risk detection device according to the embodiment of the present disclosure.

[0016] Figure 8 This is a flowchart illustrating an example of the operation of rollover risk detection performed by the rollover risk detection device according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] Hereinafter, an embodiment in which the flying object according to the present disclosure is applied to a probe will be described with reference to the accompanying drawings. In each of the drawings, the same or equivalent parts are denoted by the same reference numerals.

[0018] (Implementation Method)

[0019] While referring to Figure 1 , while briefly explaining the probe 1 involved in the embodiment. The probe 1 is a probe that travels in outer space and lands on the surface G of a celestial body P. The probe 1 includes a main body 10 and a plurality of legs 20. The legs 20 are used when the probe 1 lands on the surface G of the celestial body P, and the leg tips 21 of the legs 20 touch the surface G when the probe 1 lands. Figure 1 In the example shown, the ground G is an inclined surface, and the direction of gravitational acceleration of the celestial body P is not perpendicular to the ground G. The probe 1 is an example of a flying object according to the present disclosure.

[0020] The main body 10 of the probe 1 includes a tipping risk detection device 100. The tipping risk detection device 100 detects the risk of tipping when the probe 1 lands on the ground G. When the tipping risk detection device 100 detects the risk of tipping, the probe 1 controls its posture by, for example, controlling thrusters (not shown).

[0021] For example, Figure 1 Consider a situation where the probe 1 rotates counterclockwise. Depending on the magnitude and direction of the force acting on the probe 1, counterclockwise rotation may be suppressed, allowing the probe 1 to land normally by rotating clockwise. Alternatively, counterclockwise rotation may not be suppressed, leading to the probe directly tipping over. As described later, the tipping risk detection device 100 can detect the risk of tipping over in such a situation. The tipping risk detection device 100 is an example of a tipping risk detection device according to the present disclosure.

[0022] Next, refer to Figure 2 , while explaining the functional structure of the probe 1. As described above, the probe 1 includes a main body 10 and a plurality of legs 20. The main body 10 includes an inertial sensor 11, a leg end sensor 12, and a tipping risk detection device 100. The tipping risk detection device 100 includes a first posture angle information acquisition unit 101, a second posture angle calculation unit 102, a posture change calculation unit 103, a tipping risk detection unit 104, and a storage unit 105.

[0023] The inertial sensor 11 detects the attitude angle of the probe 1 relative to the inertial system, the gravitational acceleration of the celestial body P relative to the inertial system, and the like. Furthermore, the inertial sensor 11 may also detect the attitude angular velocity or attitude angular acceleration of the probe 1 in place of or in addition to the attitude angle of the probe 1.

[0024] Hereinafter, the posture angle of the probe 1 based on the inertial system is referred to as a first posture angle to distinguish it from the posture angle of the probe 1 based on the direction of gravitational acceleration, which will be described later.

[0025] The leg tip sensor 12 is provided at the leg tip 21 of the leg 20 , and detects the position of the leg tip 21 of the leg 20 of the probe 1 with reference to the inertial system and the contact of the leg tip 21 with the ground G.

[0026] The storage unit 105 stores shape information MD indicating information related to the shape of the probe 1 .

[0027] The first posture angle information acquisition unit 101 acquires first posture angle information regarding a first posture angle of the probe 1 with respect to the inertial system, detected by the inertial sensor 11. The first posture angle information acquisition unit 101 is an example of a first posture angle information acquisition means according to the present disclosure.

[0028] The first posture angle information includes at least one of information indicating the posture angle of probe 1 based on the inertial system, information indicating the posture angular velocity of probe 1, and information indicating the posture angular acceleration of probe 1. If any one of these information is known, the remaining information can be obtained through differential integration. However, for accuracy reasons, the first posture angle information preferably includes these multiple information.

[0029] The second posture angle calculation unit 102 calculates the posture angle of the probe 1 relative to the direction of gravitational acceleration based on the first posture angle information, the direction of gravitational acceleration relative to the inertial system detected by the inertial sensor 11, and the shape information MD stored in the storage unit 105. Hereinafter, the posture angle of the probe 1 relative to the direction of gravitational acceleration will be referred to as the second posture angle, to distinguish it from the first posture angle. The second posture angle calculation unit 102 is an example of the second posture angle calculation means involved in the present disclosure.

[0030] The posture change calculation unit 103 calculates the posture change of the probe 1 based on the second posture angle at the current time and the second posture angle at the starting point before the current time. This will be described in more detail below. The posture change calculation unit 103 is an example of a posture change calculation unit according to the present disclosure.

[0031] First, the posture change calculation unit 103 determines a certain time as the starting time. For example, the starting time can be the time when one of the leg tips 21 of the legs 20 contacts the ground G of the celestial body P, i.e., the time when landing begins. The posture change calculation unit 103 temporarily stores the second posture angle calculated by the second posture angle calculation unit 102 at the starting time.

[0032] Thereafter, the posture change calculation unit 103 calculates the posture change of the probe 1 based on the temporarily stored second posture angle at the starting point time and the second posture angle calculated by the second posture angle calculation unit 102 at the current time.

[0033] While referring to Figure 3 , while describing a specific example of posture change calculation performed by the posture change calculation unit 103. The posture change calculation unit 103 fixes a vector parallel to the gravitational acceleration direction vector at the starting point on the probe 1 and sets it as the probe fixed vector. This probe fixed vector is fixed in the coordinate system based on the probe 1. That is, even if the probe 1 rotates, the probe fixed vector remains fixed when viewed from within the probe 1. On the other hand, when viewed from outside the probe 1, such as from an inertial system, the probe fixed vector appears to rotate in sync with the rotation of the probe 1.

[0034] Next, the posture change calculation unit 103 calculates the angle formed by the current probe fixed vector and the gravitational acceleration direction vector at the current time. At the starting point, the probe fixed vector is parallel to the gravitational acceleration direction vector. Therefore, the angle formed by the current probe fixed vector and the gravitational acceleration direction vector is the angle formed by the current probe fixed vector and the probe fixed vector at the starting point. Therefore, the calculated angle becomes the posture change angle of the probe 1. In this example, the "posture change angle" is referred to as the "calculated posture change."

[0035] Furthermore, the probe fixed vector at the current time is calculated, for example, as follows. First, the posture change calculation unit 103 temporarily stores the second posture angle at the starting time. Next, the posture change calculation unit 103 calculates the probe fixed vector at the current time based on the probe fixed vector at the starting time and the difference between the second posture angle at the starting time and the second posture angle at the current time. Since the probe fixed vector is fixed in the coordinate system based on the probe 1, the difference between the second posture angle at the starting time and the second posture angle at the current time directly represents the angular difference between the probe fixed vector at the starting time and the probe fixed vector at the current time.

[0036] Refer again Figure 2 The tipping risk detection unit 104 detects the tipping risk based on the posture change and the positional relationship between the leg end 21 and the center of gravity of the detector 1. More specifically, the tipping risk detection unit 104 detects the tipping risk based on the comparison result of the posture change and the threshold value, and the positional relationship between the leg end 21 in contact with the ground G at the current moment and the center of gravity of the detector 1. As described in detail later, the threshold value is predetermined based on the geometric positional relationship between the leg end 21 and the center of gravity of the detector 1. Details on how to determine the threshold value will be described later. The tipping risk detection unit 104 is an example of the tipping risk detection unit involved in the present disclosure.

[0037] The tipping risk detection unit 104 detects the position of the leg tip 21 using the leg tip sensor 12 , and detects the position of the center of gravity of the probe 1 by referring to the shape information MD stored in the storage unit 105 .

[0038] The threshold value is predetermined based on the geometric relationship between leg tip 21 and the center of gravity of probe 1, as well as the maximum angle of inclination of the ground surface G of the assumed celestial body P. Furthermore, the geometric relationship between leg tip 21 and the center of gravity of probe 1 can be determined based on the shape of probe 1. The threshold value is determined in this way because, assuming probe 1 is not rotating immediately prior to landing, the direction of rotation of probe 1 from the moment leg tip 21 contacts ground surface G is determined by gravity, based on the position of leg tip 21 upon contact and the position of the center of gravity of probe 1.

[0039] For example, the positional relationship between the grounded leg end 21 and the center of gravity O of the detector 1 is Figure 4 In the case of the relationship shown in Figure 4 The center of gravity O is located to the right of the grounded leg tip 21 , so if the probe 1 does not rotate immediately before landing, the probe 1 rotates clockwise and the grounded leg tip 21 contacts the ground G. That is, the probe 1 lands stably.

[0040] On the other hand, the positional relationship between the grounded leg end 21 and the center of gravity O of the probe 1 is Figure 5 In the case of the relationship shown in Figure 5 The center of gravity O is located to the left of the grounded leg tips 21 , so if the probe 1 does not rotate immediately before landing, the probe 1 rotates counterclockwise and the main body 10 contacts the ground G. In other words, the probe 1 will tip over.

[0041] Therefore, considering the static relationship between the position of the leg tip 21 and the center of gravity O, it is considered that the threshold value is a posture angle above which the probe 1 will tip over if tilted. However, in reality, the probe 1 may have dynamic factors such as rotational speed and rotational acceleration that may cause it to tip over, so the threshold value is determined taking into account these static relationships and dynamic factors.

[0042] While referring to Figure 6 , while explaining an example of the rollover risk detection performed by the rollover risk detection unit 104. Figure 6 In the case of the probe 1, the center of gravity O is taken as the reference, and the grounded leg end 21 is located in the direction of gravity acceleration. Figure 6 If the time point of the state shown is set as the starting point, and if it is determined that there is no tipping risk from this state until the posture change exceeds the threshold, there is a possibility that the movement in the tipping direction will accelerate significantly at the time the posture change exceeds the threshold. Therefore, in this case, the tipping risk detection unit 104 preferably places greater emphasis on the positional relationship between the leg tip 21 in contact with the ground G and the center of gravity of the detector 1 at the current moment than on the comparison result of the posture change with the threshold when detecting tipping risk.

[0043] On the contrary, at the starting moment, when the position of the leg end 21 in contact with the ground G with reference to the center of gravity O of the detector 1 deviates significantly from the direction of gravitational acceleration, it can be expected that the movement in the direction of tipping will not accelerate much even at the time point when the posture change exceeds the threshold. Therefore, in this case, the tipping risk detection unit 104 preferably pays more attention to the comparison result of the posture change and the threshold than the positional relationship between the leg end 21 in contact with the ground G and the center of gravity of the detector 1 at the current moment to detect the tipping risk.

[0044] Next, refer to Figure 7 , while explaining an example of the hardware configuration of the rollover risk detection device 100. Figure 7 The rollover risk detection device 100 shown is implemented by, for example, a microcontroller, which is a type of computer. In addition, since the probe 1 is a probe that travels in outer space, it is preferably a computer that is resistant to cosmic rays.

[0045] The rollover risk detection device 100 includes a processor 1001 , a memory 1002 , an interface 1003 , and a secondary storage device 1004 , which are interconnected via a bus 1000 .

[0046] The processor 1001 is, for example, a CPU (Central Processing Unit). The processor 1001 reads an operating program stored in the secondary storage device 1004 into the memory 1002 and executes the program, thereby realizing various functions of the rollover risk detection device 100 .

[0047] The memory 1002 is a main storage device composed of, for example, a RAM (Random Access Memory). The memory 1002 stores the operating program read by the processor 1001 from the secondary storage device 1004. The memory 1002 also functions as a working memory when the processor 1001 executes the operating program.

[0048] The interface 1003 is an I / O (Input / Output) interface such as a serial port, a USB (Universal Serial Bus) port, a network interface, etc. The inertial sensor 11 and the leg end sensor 12 are connected to the interface 1003 .

[0049] The secondary storage device 1004 is, for example, a flash memory, a hard disk drive (HDD), or a solid state drive (SSD). The secondary storage device 1004 stores the operating program executed by the processor 1001. The secondary storage device 1004 realizes the function of the storage unit 105.

[0050] Next, refer to Figure 8 , while explaining an example of the operation of the rollover risk detection performed by the rollover risk detection device 100 of the detector 1. Figure 8 The operation shown starts, for example, when one leg end 21 of the leg 20 of the probe 1 touches the ground G of the celestial body P and the leg end sensor 12 detects the ground contact of the leg end 21. Figure 8 The actions shown begin, for example, upon landing of the probe 1 .

[0051] The posture change calculation unit 103 sets the current time as the starting time (step S101). Step S101 is executed immediately after the probe 1 lands, so the current time in step S101 is suitable as the starting time.

[0052] The first posture angle information acquisition unit 101 acquires the first posture angle information (step S102 ). Step S102 is executed immediately after step S101 , so the first posture angle information acquired in this step is the first posture angle information at the starting point.

[0053] The second posture angle calculation unit 102 calculates the second posture angle at the starting time based on the first posture angle information obtained in step S102, the direction of gravity acceleration relative to the inertial system detected by the inertial sensor 11, and the shape information MD stored in the storage unit 105, and temporarily stores it (step S103).

[0054] The posture change calculation unit 103 calculates the probe fixed vector at the starting time (step S104). The probe fixed vector at the starting time is a vector parallel to the direction of gravitational acceleration. Since step S104 is executed immediately following step S101, the probe fixed vector calculated in step S104 becomes the probe fixed vector at the starting time.

[0055] The operations of step S105 to step S109 described below are repeatedly executed, so all the data obtained in these steps become the data at the current time.

[0056] The first posture angle information acquisition unit 101 acquires the first posture angle information (step S105 ). The first posture angle information acquired in this step is information related to the first posture angle at the current moment.

[0057] The second posture angle calculation unit 102 calculates the second posture angle at the current moment based on the first posture angle information acquired in step S105 , the direction of gravity acceleration relative to the inertial system detected by the inertial sensor 11 , and the shape information MD stored in the storage unit 105 (step S106 ).

[0058] The posture change calculation unit 103 calculates the probe fixed vector at the current moment (step S107) based on the second posture angle at the current moment calculated in step S106, the second posture angle at the starting moment calculated and temporarily stored in step S103, and the probe fixed vector at the starting moment calculated in step S104.

[0059] The posture change calculation unit 103 calculates the posture change angle by obtaining the angle formed by the probe fixed vector at the starting point time obtained in step S104 and the probe fixed vector at the current time obtained in step S107 (step S108 ).

[0060] The tipping risk detection unit 104 detects tipping risk based on the posture change and the positional relationship between the leg end 21 and the center of gravity of the probe 1 (step S109). More specifically, the tipping risk detection unit 104 detects tipping risk of the probe 1 based on the comparison result of the posture change angle calculated in step S108 with the threshold value and the positional relationship between the currently grounded leg end 21 and the center of gravity of the probe 1 (step S109). The process from step S105 onwards is repeated.

[0061] The above describes the probe 1 involved in the embodiment. The tipping risk detection device 100 of the probe 1 calculates the second posture angle of the probe 1 relative to the direction of the gravitational acceleration of the celestial body P, and calculates the posture change based on the second posture angle at the starting time and the second posture angle at the current time. The tipping risk detection device 100 detects the tipping risk based on the comparison result of the posture change with the threshold value and the positional relationship between the grounded leg end 21 and the center of gravity of the probe 1 at the current time. In addition to considering the direction of the gravitational acceleration, the threshold value used in detecting the tipping risk is determined by considering a static relationship such as the geometric positional relationship between the grounded leg end 21 and the center of gravity of the probe 1. Therefore, according to the tipping risk detection device 100, the tipping risk of the probe 1 during landing can be detected by taking into account the gravity of the celestial body P.

[0062] (Variation 1)

[0063] In the embodiments, an example of the starting time is shown, using the time at the start of landing. On the other hand, if a long time has passed since the starting time, errors may accumulate in data calculated based on sensor values, such as the second posture angle and the probe fixed vector, potentially leading to erroneous detection of a rollover risk. For example, when the inertial sensor 11 detects the posture angular velocity and integrates it to calculate the posture angle, it is believed that integrated errors and errors caused by drift may accumulate. To address this issue, the starting time may be updated at regular intervals in the rollover risk detection device 100. When the starting time is updated at regular intervals, even if errors accumulate, the accumulated errors serve as a reference, thereby reducing erroneous detections of rollover risks.

[0064] Furthermore, the rollover risk detection device 100 may be configured to switch between a mode in which the start time is set at the start of landing and a mode in which the start time is updated at regular intervals. For example, if the posture angle fluctuates drastically, the rollover risk detection device 100 may operate in a mode in which the start time is set at the start of landing, while if the posture angle fluctuates smoothly, the rollover risk detection device 100 may operate in a mode in which the start time is updated at regular intervals.

[0065] (Variation 2)

[0066] In the embodiment, the flying object of the present disclosure is applied to the probe 1. However, the flying object of the present disclosure can also be applied to flying objects other than probes. For example, the flying object of the present disclosure can also be applied to unmanned aerial vehicles (UAVs) that navigate within the atmosphere. UAVs also have the risk of tipping over during landing, so the flying object of the present disclosure can be applied.

[0067] (Variation 3)

[0068] In the embodiment, the rollover risk detection device 100 performs all calculations required for detecting a rollover risk. Alternatively, a device external to the rollover risk detection device 100 may perform some of the calculations, and the rollover risk detection device 100 may communicate with the external device. For example, the function of the posture change calculation unit 103 within the rollover risk detection device 100 may be transferred to an external device. In particular, when the flying object of the present disclosure is applied to a drone, the external device may be installed on the ground, and the drone, while navigating in the atmosphere, may communicate with the external device, with the external device performing the calculations related to posture change calculations.

[0069] (Variation 4)

[0070] In the embodiment, the rollover risk detection device 100 determines the direction of the gravitational acceleration of the celestial body P using the inertial sensor 11. Alternatively, a device external to the rollover risk detection device 100 may transmit information regarding the direction of the gravitational acceleration of the celestial body P via wireless communication, and the rollover risk detection device 100 may determine the direction of the gravitational acceleration of the celestial body P by receiving this information. For example, information regarding the direction of the gravitational acceleration of the celestial body P may be transmitted by a base station located on Earth.

[0071] (Variant 5)

[0072] In the embodiment, the tipping risk detection device 100 uses the inertial sensor 11 to determine the direction of gravitational acceleration. However, when the probe 1 is in free fall, the inertial sensor 11 cannot directly detect gravitational acceleration. This is because gravitational acceleration appears to be zero within the probe system during free fall. To address this issue, the tipping risk detection device 100 may also include the following functions.

[0073] The tipping risk detection device 100 estimates the acceleration direction during free fall in real time based on the acceleration direction determined by the inertial sensor 11 before the start of free fall. Specifically, the device calculates and estimates the direction of gravitational acceleration in real time based on the acceleration direction before the start of free fall, taking into account the positional changes of the probe 1 during free fall. This calculation along the time axis performed at the start of free fall is referred to as "propagation calculation."

[0074] Furthermore, even when the celestial body P is a microgravity celestial body and the performance of the inertial sensor 11 is not very high and does not have a resolution sufficient to directly measure the gravity of the celestial body P, the above-described propagation calculation can be utilized.

[0075] (Other Modifications)

[0076] exist Figure 7 In the illustrated hardware configuration, the tipping risk detection device 100 includes a secondary storage device 1004. However, this is not limiting. Alternatively, the secondary storage device 1004 may be installed externally to the tipping risk detection device 100, and connected to the secondary storage device 1004 via an interface 1003. In this configuration, removable media such as a USB flash drive or memory card can also be used as the secondary storage device 1004.

[0077] Alternatively, you can replace Figure 7 Instead of the hardware structure shown in FIG, the rollover risk detection device 100 is constructed by using a dedicated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). Figure 7 In the hardware structure shown, part of the functions of the tipping risk detection device 100 may also be implemented by, for example, a dedicated circuit connected to the interface 1003 .

[0078] The program used in the rollover risk detection device 100 can be distributed by storing it on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD (Digital Versatile Disc), a USB flash drive, a memory card, or a HDD. Furthermore, by installing this program on a specific or general-purpose computer, the computer can function as the rollover risk detection device 100.

[0079] Alternatively, the program may be stored in a storage device of another server on the Internet and downloaded from the server.

[0080] The present disclosure is capable of various embodiments and variations without departing from the broad spirit and scope of the present disclosure. Furthermore, the aforementioned embodiments are intended only to illustrate the present disclosure and do not limit its scope. That is, the scope of the present disclosure is defined not by the embodiments but by the claims. Furthermore, variations implemented within the meaning of the claims and their equivalents are considered to be within the scope of the present disclosure.

[0081] Explanation of symbols

[0082] 1: Detector; 10: Main body; 11: Inertial sensor; 12: Leg end sensor; 20: Leg; 21: Leg end; 100: Tipping risk detection device; 101: First posture angle information acquisition unit; 102: Second posture angle calculation unit; 103: Posture change calculation unit; 104: Tipping risk detection unit; 105: Storage unit; 1000: Bus; 1001: Processor; 1002: Memory; 1003: Interface; 1004: Secondary storage device; G: Ground; MD: Shape information; O: Center of gravity; P: Celestial body.

Claims

1. A method for detecting a rollover risk when a flying object having landing legs lands on a celestial body, wherein: Acquiring first posture angle information related to a first posture angle that is a posture angle of the flying object based on an inertial system, Calculating a second posture angle as the posture angle of the flying object relative to the gravitational acceleration direction based on the posture angle information, the gravitational acceleration direction of the celestial body relative to the inertial system, and information on the shape of the flying object; Calculating the posture change of the flying object based on the second posture angle at the current time and the second posture angle at the starting point time before the current time, The risk of the flying object rolling over when landing on the celestial body is detected based on the posture change and the positional relationship between the leg tip of the leg contacting the celestial body and the center of gravity of the flying body.

2. The rollover risk detection method according to claim 1, wherein: The first posture angle information includes at least one of information indicating the posture angle of the flying object, information indicating the posture angular velocity of the flying object, and information indicating the posture angular acceleration of the flying object.

3. The rollover risk detection method according to claim 1 or 2, wherein: The direction of the gravitational acceleration is determined based on at least one of information obtained from sensors possessed by the flying body, information delivered to the flying body from outside the flying body, and information obtained by propagation calculation based on information related to acceleration obtained from sensors possessed by the flying body before the flying body starts free fall and the posture change of the flying body during free fall.

4. The rollover risk detection method according to any one of claims 1 to 3, wherein: The starting point time is the time when the flying object starts to land on the celestial body.

5. The rollover risk detection method according to any one of claims 1 to 3, wherein: The starting point time is updated at regular intervals.

6. The rollover risk detection method according to any one of claims 1 to 3, wherein: A mode in which the starting point time is the time when the flying object starts landing on the celestial body and a mode in which the starting point time is updated at regular intervals can be switched.

7. A rollover risk detection device for detecting the rollover risk of a flying object having landing legs when landing on a celestial body, wherein: The tipping risk detection device comprises: a first posture angle information acquisition unit that acquires first posture angle information related to a first posture angle that is a posture angle of the flying object with respect to an inertial system; a second posture angle calculation unit for calculating a second posture angle, which is a posture angle of the flying object relative to the direction of gravitational acceleration, based on the posture angle information, the direction of gravitational acceleration of the celestial body relative to the inertial system, and information on the shape of the flying object; a posture change calculation unit that calculates a posture change of the flying object based on the second posture angle at a current time and the second posture angle at a starting time before the current time; as well as The tipping risk detection unit detects a tipping risk when the flying object lands on the celestial body based on the posture change and the positional relationship between the leg tip of the leg contacting the celestial body and the center of gravity of the flying object.

8. A flying object comprising the rollover risk detection device according to claim 7.

9. A program for causing a computer to detect the risk of a flying object having landing legs rolling over when landing on a celestial body, wherein: The program causes the computer to: Acquiring first posture angle information related to a first posture angle that is a posture angle of the flying object based on an inertial system, Calculating a second posture angle as the posture angle of the flying object relative to the gravitational acceleration direction based on the posture angle information, the gravitational acceleration direction of the celestial body relative to the inertial system, and information on the shape of the flying object; Calculating the posture change of the flying object based on the second posture angle at the current time and the second posture angle at the starting point time before the current time, The risk of the flying object rolling over when landing on the celestial body is detected based on the posture change and the positional relationship between the leg tip of the leg contacting the celestial body and the center of gravity of the flying body.

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