Flying object

Abstract

Provided is a flying object that can reverse an airflow when approaching an upper wall surface. This flying object (flying object body) (5) comprises one or more rotor wings (17) and a spacer (18) that keeps the rotor wings (17) from contacting an upper wall surface. The rotor wings (17) have: a hub part (77) that is attached to a rotary shaft (45) of the rotor wing (17) and rotates with the rotation of the rotary shaft (45); and a plurality of blade parts (79) that have a base part (81) that is formed at the hub part (77) and extend from the hub part (77) in the direction orthogonal to the rotary shaft (45). At the blade parts (79), the angle of attack α of at least the base part (81) is 10°–60°. The length (g) to which the spacer (18) protrudes beyond the upper surfaces of the rotor wings (17) is within an upcurrent start distance (grev) at which the direction of the airflow generated by the rotation of the rotor wings reverses from down to up.

Description

flying object

[0001] The present invention relates to an air vehicle.

[0002] Small unmanned aerial vehicles (drones) control the rotation of their rotors (propellers) to ascend, descend, and control their direction of travel. When the rotors rotate, lift is generated, which gives the aerial vehicle thrust. "Thrust" is the lift generated by the rotors minus drag (the force caused by friction between the rotor surface and the fluid air). When an aerial vehicle flies, a downward airflow is generated, with the upper side of the rotors being the inlet and the lower side being the outlet.

[0003] In recent years, the use of unmanned small aerial vehicles has been explored, for example, by flying them inside buildings to inspect ceilings and under floors. For example, Patent Document 1 discloses an aerial vehicle for inspecting structures that moves while attached to the wall of a structure. Figure 7 of Patent Document 1 illustrates the state of downward airflow.

[0004] Japanese Patent Application Laid-Open No. 2021-127583

[0005] As mentioned above, when flying, an aircraft generates a downward air current, so if the aircraft flies in a space with a narrow vertical gap, the air current bounces off the lower surface, making the aircraft's posture unstable. Furthermore, the downward air current can stir up dust that has accumulated on the lower surface, causing problems such as interfering with photography by the aircraft's camera.

[0006] An object of the present invention is to provide a flying body that can blow an airflow upward from below the flying body when approaching the upper wall surface.

[0007] In order to achieve the above object, the aircraft of the present invention includes one or more rotary wings and a spacer that prevents the rotary wings from contacting the upper wall surface. The rotary wing is attached to the rotation axis of the rotary wing and has a hub portion that rotates with the rotation of the rotation axis, and a root portion is formed in the hub portion, and the rotary wing has a plurality of blade portions extending from the hub portion in a direction orthogonal to the rotation axis. The blade portion has an angle of attack α of at least the root portion in the range of 10° or more and 60° or less. The spacer has a protruding length dimension from the upper surface of the rotary wing within the blow-up start distance dimension at which the direction of the air flow generated by the rotation of the rotary wing is reversed from downward to upward.

[0008] With such a configuration, when the aircraft of the present invention approaches the upper wall surface, it is possible to blow up the air flow from below the aircraft to above.

[0009] It is a block diagram of a small unmanned aircraft system with a small unmanned aircraft (drone), which is an example of an aircraft, as the aircraft body. It is a perspective view of the aircraft body. It is a side view of the aircraft body. It is a schematic diagram for explaining the details of the left and right drive wheel mechanisms. It is a schematic diagram for explaining the details of the left drive wheel mechanism after contacting the upper wall surface. It is a plan view schematically showing the aircraft body. It is a perspective view of the first type of rotary wing. It is a view taken along arrow A1 in FIG. 7A. It is a perspective view of the second type of rotary wing. It is a view taken along arrow A2 in FIG. 8A. It is a perspective view of the third type of rotary wing. It is a view taken along arrow A3 in FIG. 9A. It is a flowchart of flight control until the aircraft body contacts the upper wall surface. It is a flowchart of the "adsorption flight mode" after the drive wheel contacts the upper wall surface. It is a conceptual diagram of an experimental device. It is a diagram in which the air flow around the rotary wing is visualized and vector-displayed when the rotary wing is rotating at a position away from the upper wall surface. It is a diagram in which the air flow around the rotary wing is visualized and vector-displayed when the rotary wing is rotating near the upper wall surface. It is a graph in which the results of Experiment 2 are plotted with the horizontal axis being g / D and the vertical axis being the thrust T [N]. The results of Experiment 2 are plotted with the horizontal axis being the angle of attack α [°] and the vertical axis being g rev15A is a graph plotting s / D as g / D. FIG. 15B is a graph plotting an approximation curve based on Equation 4 on the graph of FIG. 15A. FIG. 15C is a graph plotting an approximation curve based on Equation 5 on the graph of FIG. 15A. FIG. 15D is a graph summarizing the relationship between s / D and angle of attack α. FIG. 15E is a graph plotting the results of Experiment 3 with g / D on the horizontal axis and thrust T [N] on the vertical axis.

[0010] Hereinafter, an embodiment of an aircraft according to the present invention will be described with reference to the drawings.

[0011] Fig. 1 is a block diagram of a small unmanned aerial vehicle system in which a small unmanned aerial vehicle (drone) is used as the aerial vehicle body, which is an example of an aerial vehicle, Fig. 2 is a perspective view of the aerial vehicle body, and Fig. 3 is a side view of the aerial vehicle body. In this embodiment, as shown in Fig. 2, the forward / backward direction (X), the left / right direction (Y), and the up / down direction (Z) are defined with respect to the aerial vehicle body.

[0012] As shown in Figure 1, the small unmanned aerial vehicle system 1 includes a remote control device 3 and an aircraft main body (air vehicle) 5. In this embodiment, the aircraft main body 5 generates a downward airflow during normal flight (when there are no surrounding walls or when flying without approaching a wall), but when it approaches an upper wall and the distance between the upper wall and the rotor is within a predetermined distance, the rotor generates a swirling flow between the upper surface of the rotor and the ceiling, which generates a centrifugal negative pressure that causes an upward airflow. As a result, even when flying in a narrow space, dust accumulated on the lower surface is not stirred up, and the increased thrust caused by the negative pressure allows the aircraft main body 5 to stick to the upper wall with less power consumption than when flying in the air.

[0013] The present invention is based on the inventors' discovery of the above mechanism and further of the correlation between the shape of the blade portion of the rotor and the distance between the upper wall surface and the rotor at which the air flow reverses (the distance at which upwash begins).

[0014] The "upper wall" refers to a wall that exists above the aircraft main body 5 when it is flying, and includes, for example, the ceiling if it is inside a building. The upper wall surface is the surface of the upper wall that faces the aircraft main body 5. The upper wall surface may have a slight incline, and the surface may have some unevenness.

[0015] <Remote Control Device> The remote control device 3 is a device for remotely controlling the aircraft main body 5. The remote control device 3 includes a wireless communication device 7, an operation command device 9, and a monitoring device 11.

[0016] The wireless communication device 7 is a wireless communication device mounted on the remote control device 3 for communication between the remote control device 3 and the aircraft main body 5 (directly, the wireless communication device 19). The wireless communication device 7 uses radio waves in the 2.4 GHz frequency band, for example. The wireless communication device 7 has transmission and reception functions.

[0017] In this embodiment, the remote control device 3 and the aircraft main body 5 communicate via wireless communication using radio waves, but of course communication can also be performed via wired communication in which the remote control device 3 and the aircraft main body 5 are connected by a wire.

[0018] The motion command device 9 is a device operated by the operator to issue motion commands to the aircraft main body 5. The motion command device 9 may have a variety of configurations, such as a physical controller, a software-implemented controller, or a gesture recognition controller. A physical controller is a controller consisting of physical levers, buttons, etc. In this case, a game controller used to operate a game console may also be used. A software-implemented controller is a controller implemented in software and consisting of levers, buttons, etc. displayed graphically on a computer display screen. A gesture recognition controller is a controller that detects the operator's hand or neck movements (gestures) and commands the aircraft main body 5 to operate in response to those movements.

[0019] The monitoring device 11 is a telemetry device that monitors the internal state of the aircraft main body 5 .

[0020] <Aircraft Body> As shown in FIG. 2, the aircraft body 5 is a so-called quad rotor drone that includes a main body 13, four arm units 15A to 15D, and four rotors 17A to 17D.

[0021] As shown in FIG. 1, the aircraft main body 5 includes a wireless communication device 19, a control unit 21, a sensor unit 23, a battery 25, a voltage measurement device 27, a rotor drive unit 29, and a wheel drive unit 31.

[0022] The wireless communication device 19 is a wireless communication device mounted on the aircraft body 5 for communication between the aircraft body 5 and the remote control device 3 (directly, the wireless communication device 7). As with the wireless communication device 7, the wireless communication device 19 uses radio waves in the 2.4 GHz band, for example. The wireless communication device 19 has transmission and reception functions.

[0023] The control unit 21 is realized by a microcomputer mounted on the aircraft body 5, and a program for controlling the aircraft body 5 is executed.

[0024] The sensor unit 23 is a type of sensor that senses information necessary for flight, etc., and transmits signals to the control unit 21 of the aircraft main body 5. For example, in this embodiment, the sensor unit 23 includes a flight control sensor 33, a distance measurement sensor 35, proximity sensors 37A and 37B, and pressure sensors 39A and 39B.

[0025] The flight control sensor 33 is a sensor necessary for flight control of the aircraft main body 5. For example, it includes a three-axis gyro sensor that detects the angular velocity of the aircraft, a three-axis acceleration sensor that detects acceleration, a three-axis attitude angle sensor that detects the attitude angle of the aircraft, a GNSS (Global Navigation Satellite System) receiver, etc.

[0026] The distance sensor 35 is a distance sensor that measures the distance between the aircraft main body 5 and the upper wall surface. The proximity sensors 37A and 37B are proximity sensors that detect when the aircraft main body 5 approaches the upper wall surface below a certain threshold. The pressure sensors 39A and 39B are pressure sensors that measure the contact pressure when the drive wheels contact an upper wall surface such as a ceiling. The distance sensor 35, proximity sensors 37A and 37B, and pressure sensors 39A and 39B constitute contact detection units 61A and 61B (described below) that sense the contact state between the drive wheels 63A and the upper wall surface UW.

[0027] The battery 25 is the power source for the aircraft main body 5, and supplies power to the wireless communication device 19, the control unit 21, the sensor unit 23, the rotor drive unit 29, and the wheel drive unit 31. In this embodiment, the battery 25 is a secondary battery such as a lithium-ion secondary battery. The voltage measurement device 27 is a device that measures the voltage between the terminals of the battery 25 and transmits the voltage value to the control unit 21.

[0028] The rotor drive unit 29 has a first system consisting of a combination of a first motor driver 41A and a first motor 43A, a second system consisting of a combination of a second motor driver 41B and a second motor 43B, a third system consisting of a combination of a third motor driver 41C and a third motor 43C, and a fourth system consisting of a combination of a fourth motor driver 41D and a fourth motor 43D, corresponding to the four rotors 17A to 17D.

[0029] The first motor driver 41A to the fourth motor driver 41D are motor drive devices that control the rotation of the corresponding first motor 43A to the fourth motor 43D. Each of the first motor driver 41A to the fourth motor driver 41D has a function (ESC: Electronic Speed ​​Controller) that controls the rotation speed of the first motor 43A to the fourth motor 43D, automatically controlling the rotation speed to match an external command. The first motor driver 41A to the fourth motor 43D are also equipped with a function to output the current rotation speed to an external device. The first motor 43A to the fourth motor 43D are controlled by the corresponding first motor driver 41A to the fourth motor driver 41D to rotate the motor shafts 45A to 45D (see FIG. 2). Rotation of the shafts 45A to 45D rotates the rotors 17A to 17D fixed to the shafts 45A to 45D.

[0030] The wheel drive unit 31 has a left-side system consisting of a left-side motor driver 47A and a left-side motor 49A, and a right-side system consisting of a right-side motor driver 47B and a right-side motor 49B, corresponding to the left and right drive wheels. The left-side motor driver 47A and the right-side motor driver 47B are motor drive devices that control the rotation of the corresponding left-side motor 49A and the right-side motor 49B, respectively. The left-side motor 49A and the right-side motor 49B are controlled by the corresponding left-side motor driver 47A and the right-side motor driver 47B to rotate the motor shafts 51A and 51B (see also FIG. 4 for the shaft 51A). The rotation of the shafts 51A and 51B rotates the drive wheels 63A and 63B fixed to the shafts 51A and 51B.

[0031] 2 is a perspective view of the aircraft main body 5. As described above, the aircraft main body 5 includes the main body 13, four arm sections 15A to 15D, four rotors 17A to 17D, and the spacer 18.

[0032] The main body 13 is a part that includes a control unit 21, a sensor unit 23, a battery 25, a voltage measuring device 27, and the like.

[0033] The four arms 15A to 15D extend radially from the main body 13, and have corresponding first to fourth motors 43A to 43D attached to their tips. As described above, the first to fourth motors 43A to 43D are controlled by corresponding first to fourth motor drivers 41A to 41D, and rotate the rotors 17A to 17D fixed to the rotary shafts 45A to 45D of the motors.

[0034] The four rotors 17A to 17D are also called propellers or rotors. Rotors 17A and 17C, which are arranged diagonally across the main body 13, have the same shape and dimensions, while rotors 17B and 17D have blade angles that are opposite to those of rotors 17A and 17C. Rotors 17A and 17C rotate in the same direction, while rotors 17B and 17D rotate in the opposite direction to rotors 17A and 17C, enabling flight. In this embodiment, the diameter of rotors 17A to 17D is 127 mm. Hereinafter, unless otherwise specified, rotors 17A to 17D will be referred to as "rotors 17."

[0035] Rotor guards 53A to 53D are provided radially outward of each of the rotor blades 17A to 17D to prevent contact of the rotor blades. The rotor guard 53A has a center 53Aa at the rotation center of the rotor shaft 45A and a sector shape with an arc-shaped portion 53Ad extending from one end 53Ab to the other end 53Ac. The rotor guard 53B has a center 53Ba at the rotation center of the rotor shaft 45B and a sector shape with an arc-shaped portion 53Bd extending from one end 53Bb to the other end 53Bc. The rotor guard 53C has a center 53Ca at the rotation center of the rotor shaft 45C and a sector shape with an arc-shaped portion 53Cd extending from one end 53Cb to the other end 53Cc. The rotor guard 53D has a central portion 53Da at the rotation center of the rotary shaft 45D and is fan-shaped with an arc-shaped portion 53Dd extending from one end 53Db to the other end 53Dc.

[0036] The spacers 18 prevent the rotors 17 from colliding with the upper wall surface UW when the aircraft body 5 approaches the upper wall surface UW, while maintaining a distance between the upper wall surface UW and the rotors 17 within the upward blow-up start distance dimension at which the airflow begins to reverse. As shown in Figures 2 and 3, in this embodiment, the left and right drive wheel mechanisms 32A and 32B, and the ball casters 55 and 57, which also serve as the movement mechanisms for the aircraft body 5, are spacers 18. When the left and right drive wheel mechanisms 32A and 32B and the ball casters 55 and 57 come into contact with the upper wall surface UW, the aircraft body 5 can travel along the upper wall surface UW by rotation of the left and right drive wheel mechanisms 32A and 32B.

[0037] 3, in this embodiment, when the left drive wheel mechanism 32A and the right drive wheel mechanism 32B are separated from the upper wall surface UW, the left drive wheel mechanism 32A and the right drive wheel mechanism 32B protrude slightly upward beyond the ball casters 55, 57 (see the dashed line). This is because, when the aircraft body 5 comes into contact with the upper wall surface UW, the left drive wheel mechanism 32A and the right drive wheel mechanism 32B come into contact with the upper wall surface UW first, and the ball casters 55, 57 come into contact with the upper wall surface UW only after the aircraft body 5 is parallel to the upper wall surface UW.

[0038] The ball casters 55 and 57 have ball-shaped rollers 55a and 57a at their tips. The ball caster 55 is provided between the other end 53Ac of the rotor guard 53A and one end 53Bb of the rotor guard 53B, with the roller 55a facing upward. The ball caster 55 connects the other end 53Ac of the rotor guard 53A to one end 53Bb of the rotor guard 53B. Similarly, the ball caster 57 is provided between one end 53Db of the rotor guard 53D, with the roller 57a facing upward. The ball caster 57 connects the other end 53Cc of the rotor guard 53C to one end 53Db of the rotor guard 53D.

[0039] A gap is formed between one end 53Ab of rotor guard 53A and the other end 53Dc of rotor guard 53D. Similarly, a gap is formed between one end 53Cb of rotor guard 53C and the other end 53Bc of rotor guard 53B.

[0040] Next, the left drive wheel mechanism 32A and the right drive wheel mechanism 32B will be described using Figures 4 and 5. Figure 4 is a schematic diagram of the left drive wheel mechanism 32A and the right drive wheel mechanism 32B, showing the aircraft main body 5 flying in the air. Figure 5 is a schematic diagram of the left drive wheel mechanism 32A after contacting the upper wall surface UW.

[0041] The left drive wheel mechanism 32A is provided between the bases of the arm portions 15A and 15D and on the upper surface of the main body portion 13. The right drive wheel mechanism 32B is provided between the bases of the arm portions 15B and 15C and on the upper surface of the main body portion 13. Because the left drive wheel mechanism 32A and the right drive wheel mechanism 32B are symmetrical and have the same configuration, only the details of the left drive wheel mechanism 32A will be described below, and the right drive wheel mechanism 32B will be assigned a reference number with the letter "B" added to the reference numbers of the respective components of the left drive wheel mechanism 32A, and a description thereof will be omitted.

[0042] As shown in detail in FIG. 4, the left drive wheel mechanism 32A is provided on the upper surface of the main body 13, and includes a running part 59A and a contact detection part 61A.

[0043] The travel unit 59A is composed of the left motor 49A, the drive wheel 63A, and the motor fixing unit 65A. As described above, the left motor 49A is controlled by the left motor driver 47A to rotate the rotary shaft 51A. The rotation of the rotary shaft 51A rotates the drive wheel 63A fixed to the rotary shaft 51A.

[0044] The motor fixing part 65A includes a pair of motor support columns 67A and a tension spring 69A. The pair of motor support columns 67A are provided facing each other on the upper surface of the main body 13 and have a rotation center shaft 71A at their upper ends (note that FIG. 4 shows only one of the pair of motor support columns, with the other hidden behind the other). The pair of motor support columns 67A rotatably support the left motor 49A at a position near the rotation shaft 51A on the side of the left motor 49A, with the rotation center shaft 71A as a fulcrum. One end 69Aa of the tension spring 69A is fixed to the upper surface of the main body 13 and the other end 69Ab is fixed to a position opposite the rotation shaft 51A of the left motor 49A, and exerts a tension that pulls the left motor 49A toward the main body 13. The left motor 49A is pulled by the tension spring 69A, and is fixed in an inclined position with the rotation shaft 51A side of the left motor 49A (i.e., the drive wheel 63A side) raised upward and the opposite side of the rotation shaft 51A lowered downward, with the rotation center shaft 71A as the fulcrum, as shown in FIG. 4 . When the drive wheel 63A contacts the upper wall surface UW, the drive wheel 63A is pushed down by the upper wall surface UW, as shown in FIG. 5 . The left motor 49A rotates around the rotation center shaft 71A as the fulcrum, and the tension spring 69A is stretched. This reduces the impact caused when the drive wheel 63A contacts the upper wall surface UW. When the drive wheel 63A subsequently separates from the upper wall, the force pushing down the drive wheel 63A is released, and the restoring force of the tension spring 69A returns the left motor 49A to the state shown in FIG. 4 .

[0045] The contact detection unit 61A senses the contact state between the drive wheel 63A and the upper wall surface UW and includes a distance measurement sensor 35, a proximity sensor 37A, and a pressure sensor 39A. The distance measurement sensor 35 measures the distance between the drive wheel 63A and the upper wall surface UW (this distance is considered to be the distance between the upper wall and the aircraft main body 5), acquires distance measurements at predetermined time intervals, and transmits the distance measurements to the control unit 21. In this embodiment, one distance measurement sensor 35 is provided for each of the left drive wheel mechanism 32A and the right drive wheel mechanism 32B. Of course, one distance measurement sensor may be provided for each of the left drive wheel mechanism 32A and the right drive wheel mechanism 32B.

[0046] The proximity sensor 37A is provided on the upper end surface of the proximity sensor support 38A, and detects when the aircraft body 5 approaches the upper wall surface UW to a certain threshold or less, and sends a signal to the control unit 21.

[0047] The pressure sensor 39A is sandwiched and installed between the upper surface of the main body 13 and the motor support pillar 67A. As shown in Fig. 5, when the drive wheel 63A contacts the upper wall surface UW, the contact pressure of the drive wheel 63A is transmitted to the pair of motor support pillars 67A, 67A via the left motor 49A, and the pressure sensor 39A is compressed by the pair of motor support pillars 67A, 67A and the upper surface of the main body 13. The pressure sensor 39A transmits the measurement value at this time to the control unit 21 as the contact pressure.

[0048] [Arrangement of Rotating Wings and Drive Wheels] Figure 6 is a plan view schematically illustrating the aircraft main body 5. In Figure 6, the four arms 15A to 15D are shown as being combined to form a schematic X-shaped frame. The four rotating wings 17A to 17D are shown with solid lines as rotation ranges 73A to 73D, each representing a circle with a radius D1. Furthermore, in Figure 6, marginal ranges 75A to 75D are shown with dashed double-dashed lines around the rotation ranges 73A to 73D. The marginal ranges 75A to 75D are concentric with the rotation ranges 73A to 73D and have a radius D2 longer than the radius D1 of the rotation ranges 73A to 73D. Only the drive wheels 63A and 63B of the left drive wheel mechanism 32A and the right drive wheel mechanism 32B are shown.

[0049] The distance L between the rotation axis 45A of the rotor 17A and the rotation axis 45D of the rotor 17D is set to 200 mm, and the distance W between the rotation axis 45A of the rotor 17A and the rotation axis 45B of the rotor 17B is set to 150 mm.

[0050] As shown in FIG. 6, the drive wheels 63A, 63B are arranged so as not to enter within the margin ranges 75A to 75D so as not to interfere with the rotors 17A to 17D.

[0051] The separation distance SD between the drive wheels 63A, 63B is set in consideration of the running characteristics of the drive wheels 63A, 63B on the upper wall surface UW of the aircraft body 5. That is, if the separation distance SD is too short, the straight-line running ability of the aircraft body 5 decreases, and if it is too long, the turning ability of the aircraft body 5 decreases;

[0052] In this embodiment, the four arm sections 15A to 15D are combined to form an X-shaped frame, but it goes without saying that other frame shapes may be used, such as a so-called I-shape (a frame shape consisting of a first arm section connecting the rotation shaft 45A and the rotation shaft 45B, a second arm section connecting the rotation shaft 45C and the rotation shaft 45D, and a central arm section connecting the central sections of the first and second arm sections) or an H-shape (a frame shape consisting of a first arm section connecting the rotation shaft 45A and the rotation shaft 45D, a second arm section connecting the rotation shaft 45B and the rotation shaft 45C, and a central arm section connecting the central sections of the first and second arm sections).

[0053] [Details of Rotor] Figures 7A to 9B are diagrams showing examples of three types of rotors used for rotors 17A to 17D. However, the examples shown in Figures 7A to 9B are specifically used for rotors 17B and 17D, and as described above, the blade angles used for rotors 17A and 17C are opposite on the left and right. Here, for convenience of explanation, rotors 17A to 17D are collectively referred to as "rotor 17."

[0054] The type shown in Figure 7A (perspective view) and Figure 7B (view from the arrow A1 in Figure 7A) is a first type in which the blade has a twisted-down shape, the type shown in Figure 8A (perspective view) and Figure 8B (view from the arrow A2 in Figure 8A) is a second type in which the blade has a rectangular shape, and the type shown in Figure 9A (perspective view) and Figure 9B (view from the arrow A3 in Figure 9A) is a third type in which the blade has a twisted-up shape. The second type is indicated by adding "'" to the symbol of the first type, and the third type is indicated by adding """ to the symbol of the first type, and the explanation will be partially omitted.

[0055] The rotor 17 has a hub portion 77 and a plurality of (three in this example) blade portions 79. The hub portion 77 is attached to the rotary shaft (45A to 45D) and rotates together with the rotary shaft (45A to 45D). Each of the plurality of blade portions 79 has a root portion 81 formed in the hub portion 77 and extends from the hub portion 77 in a direction perpendicular to the rotary shaft (45A to 45D).

[0056] In the first type, the blade portion 79 has a twisted downward shape in which the angle of attack decreases from the root portion 81 to the tip portion 83, as shown in Fig. 7B. The angle of attack is the angle formed between the direction of the flow of air, which is a fluid, and the blade portion 79. Specifically, the angle of attack α of the root portion 81 is １ The angle of attack β of the tip 83 １ is greater than (α １ >β １ ).

[0057] In the second type, the blade portion 79′ has a rectangular shape with a constant angle of attack from the root portion 81′ to the tip portion 83′, as shown in FIG. ２ and the angle of attack β of the tip 83′. ２ is the same (α ２ = β ２ )

[0058] In the third type, as shown in FIG. 9B, the blade portion 79″ has a twisted shape in which the angle of attack increases from the root portion 81″ toward the tip portion 83″. Specifically, the angle of attack β ３ The angle of attack α of the root portion 81″ ３ is greater than (α ３ <β ３ ).

[0059] In an experiment conducted by the inventors, which will be described later, the blow-up phenomenon occurred in all three types, namely, the first type, the second type, and the third type. The conditions under which the blow-up phenomenon occurs will be described later.

[0060] In the following description, the first to third types will be collectively referred to as "rotor 17" without distinguishing between the shapes of the rotors.

[0061] <Flowchart> Next, an example of the control flow of the small unmanned aerial vehicle system will be described with reference to FIGS. 10 and 11. FIG.

[0062] As described above, when the distance between the upper wall surface and the rotors of the aircraft main body 5 is within a predetermined distance, a force (herein referred to as an "adsorption force") is generated that attracts the aircraft main body 5 toward the upper wall surface, and an increase in thrust occurs due to negative pressure. Therefore, based on the flowcharts of Figures 10 and 11, the aircraft main body 5 flies in "air flight mode" during normal flight, and when the spacer 18 (drive wheels 63A, 63B) comes into contact with the upper wall surface UW, the mode is switched to "adsorption flight mode" in which the rotation speed of the rotors 17A to 17D is reduced to the level necessary to maintain adhesion (contact state) to the upper wall surface UW, taking into account the adsorption force.

[0063] FIG. 10 is a flowchart of flight control until the aircraft main body 5 contacts the upper wall surface UW. First, the operator uses the motion command device 9 of the remote control device 3 to send a motion command to ascend the aircraft main body 5. The motion command is sent to the control unit 21 via the wireless communication devices 7 and 19. The control unit 21 determines the rotation speeds of the first motor 43A through the fourth motor 43D based on the motion command (step ST1) and transmits these as command values ​​to the first motor driver 41A through the fourth motor driver 41D (step ST2). During flight, the contact detection units 61A and 61B sense the contact state between the drive wheels 63A and 63B and the upper wall surface UW (step ST3). When the control unit 21 detects that the drive wheels 63A and 63B have contacted the upper wall surface UW (step ST4), the approach to the upper wall surface UW is completed, and the process proceeds to the flowchart of FIG. 11.

[0064] The control unit 21 performs contact detection (step ST4) using, for example, any of the following methods (1) to (3): (1) Method using distance measurement sensor 35 and proximity sensors 37A, 37B: The control unit 21 acquires measurement values ​​from distance measurement sensor 35 and proximity sensors 37A, 37B at predetermined time intervals. When the measurement value from distance measurement sensor 35 is within the distance at which it can be determined that contact has occurred with the upper wall surface UW and when the proximity sensors 37A, 37B detect the presence of an object (upper wall surface UW) nearby, the control unit 21 determines that the drive wheels 63A, 63B have come into contact with the upper wall surface UW. (2) Method using pressure sensors 39A, 39B: The control unit 21 acquires measurement values ​​from pressure sensors 39A, 39B at predetermined time intervals. The control unit 21 compares the measurement values ​​of the pressure sensors 39A, 39B with a threshold value Pc of the pressure sensors 39A, 39B, which is determined in advance by experimentally acquiring the measurement values ​​of the pressure sensors 39A, 39B immediately before the drive wheels 63A, 63B leave the upper wall surface UW, and determines that the drive wheels 63A, 63B have come into contact with the upper wall surface UW when the measurement values ​​of the pressure sensors 39A, 39B are equal to or greater than the threshold value Pc. (3) A method combining methods (1) and (2)

[0065] 11 is a flowchart of the "adhesion flight mode" after the drive wheels 63A, 63B come into contact with the upper wall surface UW. When the control unit 21 detects that the drive wheels 63A, 63B have come into contact with the upper wall surface UW, it switches the flight mode to the "adhesion flight mode" (steps ST11 to ST17). The adhesion flight mode continues until the operator uses the remote control device 3 to instruct the robot to leave the upper wall surface UW.

[0066] When the flight mode switches to the "adsorption flight mode," the control unit 21 first performs sensing to determine the command values ​​for the first motor 43A to the fourth motor 43D (step ST12), and determines the rotation speed of the rotors 17A to 17D (i.e., the command values ​​for the first motor driver 41A to the fourth motor driver 41D) (step ST13).

[0067] The sensing target and the rotation speed of the rotors 17A to 17D are determined, for example, by either of the following methods (1) or (2): (1) Method using pressure sensors 39A and 39B In this method, the output values ​​P of the pressure sensors 39A and 39B are measured in advance when the aircraft body 5 is horizontal with respect to the horizontal upper wall surface UW, and the drive wheels 63A and 63B are in contact with the upper wall surface UW and are maintained in sufficient contact with the upper wall surface UW (the state shown in FIG. 5). ｆｃ The control unit 21 then acquires the measurement values ​​P of the pressure sensors 39A and 39B at predetermined time intervals, and determines the rotation speed ω of the rotors 17A to 17D using the measurement values ​​according to the following equation:

[0068]

[0069] (2) Method using voltage measuring device 27 In this method, the rotation speed of the rotors 17A to 17D is gradually reduced, and the power supply voltage and the rotation speed of the rotors 17A to 17D are obtained when the drive wheels 63A, 63B start to separate from the upper wall surface UW. The rotation speed ω is calculated by adding a margin for stable adhesion to the upper wall surface from the rotation speed. O Then, the control unit 21 determines the rotation speed of the rotors 17A to 17D as ω O The first motor driver 41A to the fourth motor driver 41D are instructed to maintain the above.

[0070] After determining the rotation speed ω of the rotors 17A to 17D by any of the above methods, the control unit 21 determines the rotation speeds of the first motor 43A to the fourth motor 43D (step ST13) and sends these as command values ​​to the first motor driver 41A to the fourth motor driver 41D (step ST14). In this state, the rotation speeds of the rotors 17A to 17D are lower than the rotation speed required for the aircraft main body 5 to maintain airborne flight, thereby reducing power consumption of the battery 25.

[0071] While the aircraft main body 5 is in contact with the upper wall surface UW, the operator can cause the aircraft main body 5 to travel on the upper wall surface UW using the motion command device 9 of the remote control device 3. That is, the control unit 21 receives motion commands from the motion command device 9 for forward or backward linear movement or for turning on the spot clockwise or counterclockwise, and based on these commands, calculates motion commands for the left motor 49A and right motor 49B corresponding to the drive wheels 63A and 63B (step ST15), and transmits command values ​​to the left motor driver 47A that controls the left motor 49A and the right motor driver 47B that controls the right motor 49B, thereby causing the aircraft main body 5 to travel on the upper wall surface UW (step ST16).

[0072] <Confirmation Experiments> Experiments 1 to 3 were carried out using the experimental device ED shown in FIG.

[0073] The experimental device ED includes a simulator SM simulating the aircraft main body 5, a load cell LC, and a support base SS. Because the simulator SM simulates the aircraft main body 5, the following description omits the same reference numerals as those used for the aircraft main body 5, and the components of the simulator SM are denoted by the same reference numerals. The simulator SM differs from the aircraft main body 5 in that it includes a motor 43 built into the main body 13. The rotational force of the motor 43 is transmitted to a rotation shaft 45 at the tip of the arm 15 via a drive transmission mechanism built into the arm 15, causing the rotors 17 to rotate. In other words, all rotors 17 are designed to rotate at the same speed. Herein, the rotors are referred to as "rotors 17" regardless of their shape, number of blades, etc.

[0074] The load cell LC is a force detection sensor, and in this example, it is fixed to the support base SS and detects the force that the simulator SM pulls in the vertical direction as "thrust." In this experiment, "thrust" is the vertical component of the lift force generated by the rotor minus the vertical component of the drag force (the force caused by friction between the rotor surface and the fluid air).

[0075] The experimental device ED was installed in a laboratory with an upper wall above. The height from the floor of the laboratory to the upper wall was 976 mm. The height from the ground to the upper surface of the rotor 17 was h mm, and the height from the upper surface of the rotor 17 to the upper wall was g mm, where g was the distance from infinity to 3 mm (the limit distance g to the upper wall in this experiment). lim The thrust T [N] was measured when the rotor 17 was changed from 127 [mm] to 127 [mm].

[0076] [Experiment 1 (Experiment to confirm the blow-up phenomenon)] In Experiment 1, the above-mentioned first type (twisted down shape), second type (rectangular shape), and third type (twisted up shape) of rotors 17 were prepared, and the blow-up phenomenon of the air flow was confirmed.

[0077] 13A and 13B are vector diagrams showing the airflow around the rotor 17 visualized using the experimental apparatus shown in FIG. 12. In this experiment, the rotor 17 used was a second type (rectangular) rotor with two blades. In FIGS. 13A and 13B, the direction and speed of the airflow are shown by arrows, and the length of the arrows represents the speed of the airflow. FIG. 13A shows a state in which the rotor is not close to the upper wall surface, and FIG. 13B shows a state in which the rotor is close to the upper wall surface and upflow of the airflow occurs.

[0078] When the aircraft body 5 is not close to the upper wall surface UW, the rotor 17 of the aircraft body 5 generates a downward airflow (area AF1) as shown in Fig. 13A. In contrast, when the aircraft body 5 is close to the upper wall surface UW, the airflow reverses and becomes upward as shown in Fig. 13B (area AF2). The upward airflow hits the upper wall surface UW and then moves radially outward of the rotor 17 as the rotor 17 rotates (area AF3).

[0079] Here, the figure shows only the second type (rectangular shape) of rotor 17, but similarly, when the aircraft body 5 approaches the upper wall surface UW, the air flow reverses (blowing up phenomenon) as observed in the first type (twisted down shape) and the third type (twisted up shape).

[0080] [Experiment 2 (Experiment to Confirm the Distance at which Upwash Starts)] In Experiment 2, in order to investigate the distance between the upper wall surface and the rotor where the upwash phenomenon occurs (the distance at which upwash starts), a plurality of second type (rectangular) rotors 17 with angles of attack α of 5°, 10°, 15°, 20°, 30°, 40°, 50°, and 60° were prepared, and g was set to a value ranging from infinity to 3 mm (the limit distance g to the upper wall surface in this experiment). lim The thrust T [N] was measured when the rotation speed was changed from 0.01 to 0.15. The rotation speed of the rotor 17 was kept constant at 4000 rpm.

[0081] 14 is a graph plotting the experimental results, with the horizontal axis representing g / D (height from the top surface of the impeller 17 to the upper wall surface / diameter of the impeller 17) and the vertical axis representing thrust T [N]. The point at which thrust T becomes large is the upwash start distance, and is plotted in white in FIG.

[0082] As an additional experiment to Experiment 2, a second type (rectangular) rotor 17 with an angle of attack α = 60° was also examined, and it was confirmed that a reversal of the air flow (upward blowing) similarly occurred.

[0083] From Experiment 2 and Figure 14, the following became clear: The limit distance g to the upper wall surface lim When the angle of attack α is 0.024, the thrust T increases as the angle of attack α increases. The larger the angle of attack α, the farther the upwash start distance becomes from the upper wall surface UW. When the angle of attack α is in the range of α > 30°, the thrust reaches a plateau when approaching the upper wall surface UW. Even when the angle of attack α = 5°, the upwash phenomenon was confirmed, but the generated thrust was small and the tendency of the upwash start distance was different from the other cases. From the above, it is considered preferable that the angle of attack α of at least the root portion 81 of the blade portion 79 of the rotor 17 be in the range of 10° to 60°, and particularly 10° to 40°.

[0084] Figure 15 shows the distance from the start of blowing up. rev [mm], the horizontal axis is the angle of attack α [°], and the vertical axis is g rev From the graph in FIG. 15A, g rev / D is the angle of attack α and g rev It was found that the results could be expressed by an approximate curve obtained by regression analysis based on the relationship between σ and σ.

[0085] Here, the regression equation will be explained using [Equation 2].

[0086] Here, A and B are the blade shape and solidity S d Solidity is a dimensionless quantity defined as (blade area per rotor) / (rotating area per rotor), and is expressed by [Equation 3].

[0087] Here, b is the number of blades, c is the chord length, R b is the radius of each blade, R is the radius of the entire rotor, and π is the constant of the circumference of a circle.

[0088] For example, b=3, c=14.8 mm, R b = 63.5 mm, R = 63.5 mm, and the regression analysis method is rev When the exponential approximation curve that minimizes the error of the linear equation obtained by taking the logarithm of both sides of [Equation 2] is obtained using the regression equation for / D, g rev / D is expressed by [Equation 4].

[0089] FIG. 15B is a graph of [Equation 4].

[0090] As another regression analysis method, when the approximate equation is obtained by the least squares method using [Equation 2] as the regression equation, g rev / D is expressed by [Equation 5].

[0091] FIG. 15C is a graph of [Equation 5].

[0092] Therefore, the protruding length g of the spacer 18 from the upper surface of the rotor 17 is equal to the blow-up start distance g, which is calculated by modifying [Equation 4] or [Equation 5] and substituting the rotor diameter D. rev If the distance is set within this range, when the aircraft body 5 comes into contact with the upper wall surface UW, the airflow generated by the rotor will be blown up.

[0093] Although the regression equation described here is the exponential function of α, which is represented by [Equation 2], it goes without saying that a polynomial of α may also be used as the regression equation.

[0094] FIG. 16 shows the effective spacer height (height of the spacer 18 capable of maintaining the blow-up phenomenon (length of protrusion from the upper surface of the rotor blade 17)) s [mm], where s = g rev -g lim 16 is a graph showing the relationship between s / D and angle of attack α (10°, 15°, 20°, 30°, 40°, 50°, 60°) with the definition: From Fig. 16, it was found that the range of effective spacer height s [mm] expands as the angle of attack α increases.

[0095] [Experiment 3 (Experiment to Confirm Differences Due to Rotor Shape)] In Experiment 3, in order to investigate differences due to the rotor shape, multiple rotors 17 of the first type (twisted down shape), the second type (rectangular shape), and the third type (twisted up shape) were prepared, and g was set to 3 mm from infinity (the approach limit distance g to the upper wall surface in this experiment). lim ), and the thrust T [N] was measured when the g / D was changed from 0.01 to 0.15. Figure 17 is a graph plotting the results of Experiment 3, with the horizontal axis representing g / D and the vertical axis representing thrust T [N]. Five types of rotors 17, No. 1 to No. 5, were prepared, as shown in the legend in Figure 17. The rotation speed of the rotors 17 was kept constant at 4000 rpm. For No. 3 to No. 5, the thrust T at infinity was roughly the same. The "twist down / twist up" column is written as "angle of attack α of root portion 81 - angle of attack β of tip portion," and a "-" is written for rectangular shapes.

[0096] From Experiment 3 and Figure 17, the following became clear: ・In all of No. 1 to No. 5, the upflow phenomenon was confirmed, and an increase in thrust was observed. ・Comparing No. 3 to No. 5, the approach limit distance g to the upper wall surface was limAt (g / D = 0.024), No. 3 (third type (up-twist shape)) has the greatest increase in thrust, followed by No. 5 (first type (down-twist shape)). However, in the case of No. 3 (third type (up-twist shape)), the angle of attack increases toward the tip 83, resulting in greater torque and therefore greater power consumption. In contrast, No. 5 (first type (down-twist shape)) has a smaller torque than No. 3 (third type (up-twist shape)), and therefore has the advantage of less power consumption than No. 3 (third type (up-twist shape)). Comparing No. 2 and No. 5, which are first type (down-twist shape), No. 5 has a greater increase in thrust.

[0097] To summarize Experiments 1 to 3, the following can be said: To obtain the effect of increasing thrust due to the upwash phenomenon, it is preferable that the angle of attack α of at least the root portion 81 be in the range of 10° to 60°, and particularly 10° to 40°. The spacer 18 only needs to have a protruding length dimension g from the upper surface of the rotor 17 that is within the upwash start distance dimension. In this embodiment, from the perspective of increasing thrust due to the upwash phenomenon and reducing power consumption, the rotor 17 of the first type (twisted down shape) is suitable. When the angle of attack α of the root portion 81 is in the range of 30° to 40°, it is preferable that the angle of attack β of the tip portion 83 be in the range of 10° to 15°. As an additional experiment to Experiment 3, the first type (twisted down shape) rotor 17 with an angle of attack α of 40° and an angle of attack β of 15° was also checked, and it was confirmed that the thrust at the approach limit was greater than that of the first type (twisted down shape) with an angle of attack α of 30° and an angle of attack β of 15°. Therefore, for example, in the case of the rotors prepared in Experiment 3, rotor No. 5, with an angle of attack α of 30° at the root portion 81 and an angle of attack β of 15° at the tip portion 83, has a good balance between the increase in thrust due to the upwash phenomenon and power consumption.

[0098] <Function of the Flying Object> The function of the flying object will be described below.

[0099] The rotor 17 of the aircraft (aircraft body) 5 of this embodiment has a blade portion 79 with an angle of attack α of at least the base portion 81 in the range of 10° to 60°, and the spacer 18 has a protruding length dimension g from the upper surface of the rotor 17 that is equal to or larger than the upward blowing start distance dimension g at which the direction of the airflow generated by the rotation of the rotor 17 reverses from downward to upward. rev Within.

[0100] By providing the rotors 17 and spacers 18 in this manner, when the flying object 5 rises to the upper wall surface UW until the spacers 18 come into contact with it, the direction of the airflow generated by the rotation of the rotors 17 reverses from downward to upward (blowing-up phenomenon). This makes it less likely for turbulence to occur below the flying object 5, stabilizing the flying object's posture even when the flying object 5 flies in a narrow space above and below. It also prevents dust that has accumulated on the underside from being stirred up. Furthermore, due to the force of attraction (adsorption) that pulls the flying object 5 toward the upper wall surface, it is possible to maintain contact with the upper wall surface UW with fewer rotations than when hovering at a constant altitude.

[0101] The angle of attack α [°], the diameter of the rotor 17 is D [mm], and the upflow start distance is g rev When expressed in [mm], g rev / D is the angle of attack α and g rev The regression equation is expressed by an approximate curve obtained by regression analysis based on the relationship between σ and D. For example, the regression equation is given by Equation 2.

[0102] Here, A and B are the blade shape and solidity S d Solidity is a dimensionless quantity defined as (blade area per rotor) / (rotating area per rotor), and is expressed by [Equation 3].

[0103] Here, b is the number of blades, c is the chord length, R b is the radius of each blade, R is the radius of the entire rotor, and π is the constant of the circumference of a circle.

[0104] Therefore, the spacer 18 has a protruding length g from the upper surface of the rotor 17, which is calculated by modifying [Equation 2] to the blow-up start distance g rev It is preferable to make it within.

[0105] The blade portion 79 may have a rectangular shape or an up-twisted shape in which the angle of attack increases from the root portion 81 to the tip portion 83, but it is more advantageous if the blade portion 79 has a down-twisted shape in which the angle of attack decreases from the root portion 81 to the tip portion 83. When the blade portion 79 has a down-twisted shape, a better balance is achieved between the increase in thrust due to the upflow phenomenon and power consumption compared to a rectangular shape or an up-twisted shape.

[0106] Furthermore, experiments have shown that when the angle of attack of the tip 83 of the blade portion 79 is β [°], if the angle of attack α is in the range of 30° or more and 40° or less, and the angle of attack β is in the range of 10° or more and 15° or less, then there is a good balance between the increase in thrust due to the updraft phenomenon and power consumption.

[0107] Since the flying vehicle 5 is in contact with the upper wall surface UW, it may further include a movement mechanism for traveling along the upper wall surface UW. For example, the movement mechanism (left drive wheel mechanism 32A, right drive wheel mechanism 32B, ball casters 55, 57) may also serve as the spacer 18. Of course, the movement mechanism may also include a ducted fan that generates horizontal thrust. When the flying vehicle 5 is in contact with the upper wall surface UW and an airflow is blowing up, the airflow generated by the rotor 17 does not interfere with the airflow generated by the ducted fan, allowing the ducted fan to efficiently generate horizontal thrust.

[0108] Furthermore, as described above, in this embodiment, when the flying object 5 is in contact with the upper wall surface, a force (adsorption force) is generated in the flying object 5 that pulls the flying object 5 toward the upper wall surface. Therefore, the rotation speed of the rotors may be reduced to maintain the flying object 5 in contact with the upper wall surface UW. Therefore, the control unit 21 is provided with a control unit that controls the rotation speed of one or more rotors 17 and contact detectors 61A, 61B that sense the contact state between the spacer 18 and the upper wall surface UW. When the control unit 21 detects via the contact detectors 61A, 61B that the spacer 18 has come into contact with the upper wall surface UW, the control unit 21 may reduce the rotation speed of one or more rotors 17 to a rotation speed at which the spacer 18 can maintain contact with the upper wall surface UW.

[0109] Although the embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments, and it goes without saying that modifications are possible within the scope of the technical concept of the present invention.

[0110] For example, in the above example, the angle of attack of the rotor increases or decreases linearly as it approaches the tip from the root, but it may of course increase or decrease nonlinearly.

Claims

1. An aircraft comprising: one or more rotors; and a spacer that prevents the rotors from contacting an upper wall surface, wherein the rotors have a hub portion that is attached to the rotor shaft of the rotor and rotates together with the rotor shaft; and a base portion formed on the hub portion and a plurality of blade portions extending from the hub portion in a direction perpendicular to the rotor shaft, wherein the angle of attack α of at least the base portion of the blade portions is in the range of 10° to 60°, and the protruding length dimension of the spacer from the upper surface of the rotor is within the upflow start distance dimension at which the direction of the airflow generated by the rotation of the rotor reverses from downward to upward.

2. The angle of attack α [°], the diameter of the rotor blade D [mm], and the blow-up start distance g rev When expressed in [mm], g rev / D is the angle of attack α and g rev 2. The flying object according to claim 1, characterized in that the abscissa is represented by an approximation curve obtained by regression analysis based on the relationship between the ordinate and abscissa and the abscissa.

3. The aircraft according to claim 1, characterized in that the blade portion has a twisted shape in which the angle of attack decreases as it approaches the tip from the base portion.

4. The flying object described in claim 3, characterized in that, when the angle of attack of the tip of the blade portion is β [°], the angle of attack α is in the range of 30° to 40°, and the angle of attack β is in the range of 10° to 15°.

5. The flying object according to claim 1, further comprising a movement mechanism for traveling on the upper wall surface.

6. The aircraft described in claim 1, further comprising: a control unit that controls the rotation speed of the one or more rotors; and a contact detection unit that senses the contact state between the spacer and the upper wall surface, wherein when the contact detection unit detects that the spacer has come into contact with the upper wall surface, the control unit reduces the rotation speed of the one or more rotors to a rotation speed at which the spacer can maintain its contact with the upper wall surface.