JP6592679B1 - Unmanned aerial vehicle - Google Patents

Abstract

The present invention provides an unmanned aerial vehicle capable of eliminating the troublesome adjustment of the optimal pitch of a propeller while suppressing the complexity and instability of a fuselage structure and a flight program. A pitch change mechanism that includes a plurality of rotors and changes a pitch angle of the plurality of rotors, and a speed controller that controls a rotation speed of each rotor, wherein the pitch change mechanism includes the rotors. The pitch angles of these rotors are changed so that the pitch angles of the rotors are all the same, and the movement in the air is performed by controlling the rotational speed of each of the rotors. [Selection] Figure 5

Description

  The present invention relates to unmanned aerial technology.

  In recent years, improvements in sensors and software used for attitude control and autonomous flight of unmanned aerial vehicles have advanced, and the performance and operability of unmanned aerial vehicles have improved dramatically. In particular, multi-copters flying with multiple fixed-pitch propellers have a simpler rotor structure than helicopters, and are easier to design and maintain, so applications for various missions in a wide range of industrial fields are being studied. .

  Patent Document 1 below discloses a multicopter including a variable pitch mechanism of a rotor.

JP 2017-185945 A

  While the fixed pitch propeller multicopter has the above-mentioned advantages, there is also a problem that the propeller itself must be replaced when the pitch angle of the propeller is changed. In particular, in order to identify the optimal pitch angle according to the weather conditions and payload at the time of flight, the propeller replacement work may have to be repeated several times before the flight.

  As a solution to such a problem, it is conceivable to employ a rotor having a variable pitch. However, the rotor pitch changing mechanism has a large number of parts, and there is a concern that the airframe structure and the flight program become complicated. The complexity of the design and the decrease in maintainability detract from the original advantages of the multicopter.

  In the invention of Patent Document 1, a servo motor that is a driving source of the pitch changing mechanism is directly connected to the pitch changing mechanism. In the invention of Patent Document 1, since each pitch changing mechanism is provided with a drive source, it is possible to individually adjust the pitch angle of each rotor, and flexibly cope with increase / decrease in the number of rotors. It is considered possible. On the other hand, since the tip weight of the arm is increased by the amount corresponding to the servo motor, the stability and agility of the flight operation is reduced. In addition, when the pitch angle control is accompanied by the movement in the air as in the multi-copter of Patent Document 1 (paragraph 0015), a commercially available general flight controller cannot cope with such control, so that it is separately separately provided. I need to create a flight controller.

  In view of the above problems, the problem to be solved by the present invention is to provide an unmanned aerial vehicle capable of eliminating the troublesome adjustment of the optimal pitch of the propeller while suppressing the complexity and instability of the airframe structure and the flight program. There is.

  In order to solve the above problems, an unmanned aerial vehicle according to the present invention includes a plurality of rotors, a pitch changing mechanism that changes a pitch angle of the plurality of rotors, and a speed controller that controls the rotational speed of each rotor, The pitch changing mechanism is characterized in that the pitch angles of the rotors are changed so that the pitch angles of the rotors are all the same, and the movement in the air is performed by controlling the rotational speed of the rotors.

  The pitch change mechanism provided in the unmanned aerial vehicle of the present invention changes these pitch angles so that the pitch angles of the rotors are all the same, and does not adjust the pitch angles of the individual rotors individually. . Therefore, the thrust of each rotor cannot be made unbalanced by controlling the pitch angle, and the unmanned aircraft cannot fly horizontally.

  The unmanned aerial vehicle of the present invention uses the pitch changing mechanism only to adjust the pitch angle of the rotor uniformly, and the movement in the air is performed exclusively by controlling the rotational speed of each rotor. In other words, the pitch changing mechanism of the present invention allows the pitch angle of the fixed pitch propeller to be changed without replacing the propeller. The pitch changing mechanism differs from the general pitch changing mechanism in its use and technical idea. ing.

  The pitch changing mechanism of the present invention can be simplified in structure by narrowing down its functions and applications. Furthermore, the unmanned aerial vehicle of the present invention can adopt an existing flight controller for a multicopter without modification by performing the movement in the air exclusively by controlling the rotational speed of the rotor. That is, according to the unmanned aircraft of the present invention, it is possible to eliminate the troublesome adjustment of the optimal pitch of the propeller while suppressing the complexity and instability of the airframe structure and the flight program.

  Further, it is preferable that the pitch changing mechanism is configured to simultaneously change the pitch angles of the plurality of rotors by the same amount while keeping the pitch angles of the rotors at the same angle.

  The fixed-pitch propeller multicopter maintains its altitude by lowering the number of revolutions of the propeller (synonymous with the rotational speed) when the aircraft is pushed up by an updraft during flight. Naturally, when it is blown by a strong updraft, it is necessary to reduce the rotation speed accordingly. However, in order for the propeller to perform its original function, a rotation speed sufficient to obtain a gyro effect is required. When the speed of the propeller is lowered beyond its lower limit, the propeller stalls and the multicopter becomes unsteerable. In order to increase the energy efficiency of the rotor, it is desirable to rotate the propeller at a low speed, but this also means that it becomes vulnerable to the updraft.

  The pitch change mechanism can change the pitch angle of these rotors at the same time while keeping all the pitch angles of the rotors at the same angle. When it is likely to happen, the pitch angle is temporarily reduced to reduce the thrust with respect to the rotational speed of each rotor, so that the rotational speed can be maintained and stalling of these rotors can be avoided.

  The pitch changing mechanism preferably includes one or a plurality of motors that are driving sources of the pitch changing mechanism, and the number of the motors is preferably smaller than the number of the rotors. At this time, it is more preferable that the pitch changing mechanism changes all pitch angles of the plurality of rotors by one motor that is a driving source of the pitch changing mechanism.

  The pitch changing mechanism of the present invention changes the plurality of rotors so that the pitch angles of these rotors are all the same. This feature allows the pitch angles of all rotors to be operated simultaneously with a small number of motors. When the pitch changing mechanism includes a motor for each rotor, the number of motors to be mounted is increased by the number of rotors, the body weight is increased, and the power consumption is also increased. By driving the pitch changing mechanism with a smaller number of motors than the number of rotors, such difficulties associated with the adoption of the pitch changing mechanism can be alleviated. In particular, when a single motor is used, the pitch angle synchronization accuracy can be increased in addition to maximizing the weight reduction effect and power saving effect of the pitch changing mechanism.

  The pitch changing mechanism preferably changes the pitch angle of each rotor by collective pitch control, and does not perform cyclic pitch control for the plurality of rotors.

  As described above, the unmanned aerial vehicle of the present invention uses the pitch changing mechanism only for adjusting the pitch angle of the rotor uniformly, and the movement in the air is performed exclusively by controlling the rotational speed of each rotor. Therefore, the pitch changing mechanism of the present invention does not need to perform cyclic pitch control. By removing the structure related to cyclic pitch control from the pitch changing mechanism, the pitch changing mechanism can be simplified.

  The unmanned aerial vehicle of the present invention includes a center frame that is a center portion of the fuselage, and a plurality of arms that extend radially from the center frame in plan view, and the plurality of rotors are respectively supported by the arms. Each rotor has a blade that is a rotor blade, and a rotor hub to which the blade is connected, and the rotor hub is coupled to a rotor shaft that is a rotating shaft, and the pitch changing mechanism is provided for each rotor. Further, a slider member connected to the blade by a pitch link that is a link member, a pitch leveler that is a mechanism for moving the slider member up and down along the rotor shaft, and a rod-like link member that operates the pitch leveler. A first control rod, wherein the first control rod includes the center frame. Al wherein are arranged along each arm, the pitch changing mechanism may be configured to all the first control rod along said each arm to the same amount back and forth at the same time.

  In general, as the weight of the arm tip increases, the posture of the multicopter becomes less stable due to the inertia of the arm tip, and the agility of the flight operation is impaired. Furthermore, the load at the end of the arm hinders the exhaust flow of the rotor and disturbs the propulsion direction of the rotor. By making the pitch angle of each rotor operable from the center frame side via the first control rod, the drive source of the pitch changing mechanism can be disposed on the center side of the machine body. Thereby, the weight of the tip of each arm can be reduced, and the influence on the stability and agility of the flight operation due to the pitch changing mechanism can be reduced.

  Also, at this time, a control hub, which is a hub member that rotates horizontally by the output of the motor, is disposed on the center frame, and each of the first control rods has a base end connected to the control hub. It is good.

  More specifically, the four rotators are provided, and a servo horn that is an output portion of the motor is disposed in the center of the center frame, and the center frame has the above-mentioned when the center frame is viewed in plan view. A pair of the control hubs are arranged at positions that are point-symmetric with respect to the rotational center of the servo horn, and the servo horn and each control hub are connected by a second control rod that is a rod-shaped link member, Each of the control hubs is connected with two first control rods, and the pair of control hubs are configured to simultaneously connect the four first control rods along the arms by the rotation of the servo horn. It is good also as a structure which carries out quantity advance / retreat.

  When changing the pitch angle of all the rotors with one motor, the operation of all the first control rods can be mechanically synchronized with a simple structure, thereby improving the reliability of the pitch angle changing operation. Further, the weight of the pitch changing mechanism can be suppressed.

  The unmanned aerial vehicle of the present invention has a pitch adjustment program that is a program for automatically controlling the pitch changing mechanism, and when the rotational speed of each rotor falls below a predetermined threshold value, the plurality of pitch adjustment programs are the plurality of pitch adjustment programs. The pitch angle of the rotor may be automatically reduced.

  When there is a risk that the attitude control may be disturbed due to the rotor speed falling below a predetermined threshold, such as when it is swept up by an updraft, the pitch adjustment program will automatically reduce the pitch angle to reduce the thrust for each rotor speed. By lowering the value and maintaining the rotational speed of the rotor, it is possible to prevent the rotor from stalling.

  In addition, the unmanned aerial vehicle of the present invention may be configured such that the pitch adjustment program automatically reduces the pitch angles of the plurality of rotors when the rotational speed of each rotor falls below a predetermined threshold.

  As mentioned above, in order to increase the energy efficiency of the rotor, it is desirable to rotate the rotor at a low speed, but at the same time, it is also vulnerable to the updraft. The pitch adjustment program monitors the rotational speed of the rotor and automatically keeps the pitch angle large within a safe range, thereby improving the energy efficiency of the rotor while avoiding the stall of the rotor.

  As described above, according to the unmanned aerial vehicle of the present invention, it is possible to eliminate the troublesome adjustment of the optimum pitch of the propeller while suppressing the complexity and instability of the airframe structure and the flight program.

It is a perspective view which shows the external appearance of the multicopter concerning this embodiment. It is a see-through | perspective perspective view which shows the structure in the center frame of FIG. It is a see-through | perspective perspective view which shows the structure of the pitch change mechanism of a multicopter. It is the elements on larger scale which show the mechanism of an arm front-end | tip. It is a side view which shows the pitch angle change operation | movement of a rotor by a pitch change mechanism. It is a side view sectional view showing the drive mechanism of a rotor. It is a block diagram which shows the function structure of a multicopter. It is a block diagram which shows the function structure of the modification of a multicopter.

  Hereinafter, embodiments of the present invention will be described. The following embodiment is an example of the multicopter 10 that is an unmanned aerial vehicle including a plurality of rotors. In the following description, “upper”, “lower”, and “vertical” are directions parallel to the Z axis in the coordinate axis display depicted in FIGS. 1 and 2, and the arrow direction of the Z axis is the upper direction. To do. “Horizontal” means an XY plane (direction) in the same coordinate axis display.

(Configuration overview)
FIG. 1 is a perspective view showing an appearance of a multicopter 10 according to the present embodiment (hereinafter also referred to as “this example”). FIG. 2 is a perspective view showing a configuration inside the center frame 11 of FIG. FIGS. 1 and 2 illustrate a mechanical structure related to driving and control of the rotor 43 included in the multicopter 10, and actually a flight controller FC, ESC 24, battery 60, and the like, which will be described later, are mounted thereon. In addition, for example, a cover member that covers the center frame 11, a landing gear, an external device according to various uses, and the like may be provided.

  The multicopter 10 of this example includes a center frame 11 that is a frame member disposed at the center of the airframe, and four arms 12 that extend radially from the center frame 11 in plan view. The center frame 11 is configured by flat plate members having a substantially cross shape in plan view arranged in parallel vertically. The arm 12 is a cylindrical pipe material, and is arranged so as to extend from each end of the cross of the center frame 11 in the same direction as these ends. Each arm 12 is fixed in the center frame 11 with an arm clamp 121 as a clamp member at the base end, and a rotor 43 is supported at the tip of each arm 12.

  In the multicopter 10 of this example, a motor 41 that is a drive source of each rotor 43 is disposed in the center frame 11. These motors 41 are fixed to a motor mount 419 provided on the center frame 11 so that their output shafts face each arm 12 side. Outputs of these motors 41 are transmitted to the rotor 43 through power transmission members disposed in the respective arms 12.

  Commercially available general multicopters often employ a structure in which a motor is disposed at the tip of each arm and a fixed pitch propeller is directly connected to the output portion. However, as the weight of the tip of the multicopter increases, the posture of the multicopter becomes less stable due to the inertia of the tip of the arm, and the agility of the flight operation is impaired. In the multicopter 10 of this example, the motor 41 is disposed on the center frame 11 to reduce the weight of the tip of the arm 12 and to improve the stability and agility of the flight operation.

  Further, the rotor 43 of this example is a variable pitch propeller capable of changing the pitch angle. As will be described in detail later, the multicopter 10 of this example adjusts the pitch angles of the rotors 43 so that the pitch angles of the rotors 43 are all the same, and the movement in the air is exclusively the rotational speed of the rotors 43. Perform by control. As a result, the complexity and instability of the airframe structure and flight program are suppressed, and the trouble of adjusting the optimal pitch of the propeller is eliminated.

(Pitch change mechanism)
FIG. 3 is a perspective view illustrating the configuration of the pitch changing mechanism PC of the multicopter 10. FIG. 4 is a partially enlarged view showing the mechanism at the tip of the arm 12.

  As described above, the pitch changing mechanism PC of this example does not individually adjust the pitch angles of the individual rotors 43, but keeps the pitch angles of the respective rotors 43 at the same angle while maintaining the pitch angles of the rotors 43. The pitch angle is simultaneously changed by the same amount. Therefore, the pitch changing mechanism PC cannot control the pitch angle so that the thrust of each rotor 43 is unbalanced, and cannot use it to fly the aircraft horizontally.

  The pitch changing mechanism PC of this example is mainly composed of a servo motor 71, a first control rod 81, a pitch lever 82, and a slider member S.

  The servo motor 71 is a drive source for the pitch changing mechanism PC. The servo motor 71 is fixed to the center frame 11, and an oval servo horn 711, which is an output part thereof, is disposed at the center of the center frame 11. One end of a second control rod 73 that is a rod-shaped link member is connected to both ends of the servo horn 11 in the longitudinal direction, and the other end of the second control rod 73 is connected to the control hub 72.

  The control hub 72 is a hub member supported by a lower plate constituting the center frame 11. A pair of control hubs 72 in this example are disposed at positions that are point-symmetric with respect to the center of rotation of the servo horn 711 when the center frame 11 is viewed in plan. Each control hub 72 is a fan-shaped member in a plan view, and can be rotated horizontally around a portion corresponding to the central angle of the fan-shaped center. The other end of the second control rod 73 is connected to a portion corresponding to the center of the arc constituting the sector of each control hub 72. As a result, the pair of control hubs 72 rotate symmetrically within a predetermined angle range in conjunction with the servo horn 11.

  One end (base end portion) of a first control rod 81 that is a rod-shaped link member is connected to a portion corresponding to the vicinity of the distal ends of the two radii constituting the fan shape of each control hub 72. Two first control rods 81 are connected to each control hub 72, and these control hubs 72 operate a total of four first control rods 81. The four first control rods 81 are arranged along different arms 12.

  With the above configuration, the pitch changing mechanism PC of the present example can simultaneously advance and retract the four first control rods 81 by the same servo motor 71 by the same amount. Although the details will be described later, the other ends of the first control rods 81 are connected to the slider members S. By moving the first control rods 81 along the respective arms 12, the slider members S are interposed. Thus, the pitch angles of all the rotors 43 can be changed.

  As described above, the pitch changing mechanism PC in this example changes the four rotors 43 so that the pitch angles of the rotors 43 are all the same. This feature makes it possible to simultaneously operate the pitch angles of all the rotors 43 with one servo motor 71. When the pitch changing mechanism includes a motor for each rotor, the number of motors to be mounted is increased by the number of rotors, the body weight is increased, and the power consumption is also increased. In the multicopter 10 of this example, such a difficulty associated with the adoption of the pitch changing mechanism PC is alleviated by driving the pitch changing mechanism PC with one servo motor 71. In this example, the accuracy of pitch angle synchronization is improved by using one servomotor 71. However, the pitch change mechanism PC is driven by a smaller number of servomotors 71 than the number of rotors 43 to a certain extent. The lightening effect and power saving effect can be obtained.

  In general, as the weight of the tip of the multicopter increases, the posture of the multicopter becomes less stable due to the inertia of the arm tip, and the agility of the flight operation is impaired. Furthermore, the load at the end of the arm hinders the exhaust flow of the rotor and disturbs the propulsion direction of the rotor. In the pitch changing mechanism PC of the present example, the pitch angle of each rotor 43 can be operated from the center frame 11 side via the first control rod 81, whereby the drive source (servo motor 71) of the pitch changing mechanism PC is set. It can be placed on the center side of the aircraft. Thereby, the weight of the tip of each arm 43 is reduced, and the influence on the stability and agility of the flight operation due to the provision of the pitch changing mechanism PC is suppressed.

  When the pitch angle of all the rotors 43 is changed by one servo motor 71, the operation of all the first control rods 81 is mechanically synchronized with a simple structure, so that the reliability of the pitch angle changing operation can be improved. In addition, the weight of the pitch changing mechanism PC itself is suppressed.

  Hereinafter, the pitch lever 82 and the slider member S will be described with reference to FIG. In the following description based on FIG. 4, the front end side (the arrow f side in FIG. 4) of the arm 12 is “front”, and the opposite side (the arrow r side in FIG. 4) is “rear”.

  A rotor base 13 that is a support member of the rotor 43 is attached to the tip of the arm 12. The rotor base 13 of this example includes a socket part 131, a support plate 132, and a reinforcing post. The socket part 131 is a cylindrical connection member that is screwed to the tip of the arm 12. The support plate 132 is two plate-like portions extending forward from the socket portion 131, and these are arranged horizontally and parallel in the vertical direction. The reinforcing post 133 is a cylindrical reinforcing material that prevents the support plate 132 from being bent. The reinforcing posts 133 are vertically arranged between the front end portions of the two support plates 132. The two support plates 132 restrict each other's deflection through the reinforcing posts 133, thereby increasing the rigidity of the support plate 132.

  The pitch lever 82 is a mechanism for moving the slider member S up and down along the rotor shaft 44, and is a form of the pitch leveler of the present invention. The pitch lever 82 is a hinge member whose one end is rotatably supported by a pitch lever base 821 which is a pedestal fixed to the upper surface of the support plate 132. The first control rod 81 is connected to the pitch lever 82 via a pitch lever link 811 which is a link member. The pitch lever 82 pivots up and down around the connecting portion with the pitch lever base 821 as the first control rod 81 advances and retreats along the arm 12.

  The slider member S moves up and down along the rotor shaft 44 to rotate the feathering hinge 88 to which the blade 432 of the rotor 43 is connected in the pitch direction of the blade 432. That is, the pitch angle of the rotor 43 is changed.

  The rotor 43 of this example includes a rotor hub 431 on which a feathering hinge 88 is rotatably supported, a blade 432 that is a rotary blade, and a blade base 433 that holds the blade 432 in a foldable manner. The rotor hub 431 is coupled to the rotor shaft 44 and rotates integrally with the rotor shaft 44. The blade base 433 is coupled to the feathering hinge 88 and rotates integrally with the feathering hinge 88.

  The slider member S of this example is mainly composed of a pitch control plate 85 and a slider ring 86.

  The pitch control plate 85 has a cylindrical body portion through which the rotor shaft 44 is inserted, and a pair of arm portions extending in the front-rear direction from the body portion, and these arm portions are connected to the feathering hinges 88. One end of the two pitch links 851 is rotatably supported. The slider ring 86 is provided with two annular flange portions 861 which are continuous in the circumferential direction on the outer peripheral surface of the cylindrical body portion. Between these flange parts 861, the groove part 862 continued in the circumferential direction of the outer peripheral surface is formed.

  The pitch control plate 85 and the slider ring 86 are coupled by a slider sleeve 87, which is a cylindrical sleeve member 87 disposed inside these barrels, and move integrally up and down. The slider sleeve 87 is a half screw member having a head part whose outer peripheral surface is enlarged in a flange shape, and is arranged with the head part facing down and the thread part facing up. A pitch control plate 85 is screwed into the threaded portion of the slider sleeve 87, and a slider ring 86 is disposed between the pitch control plate 85 and the head of the slider sleeve 87. The slider ring 86 is supported by the slider sleeve 87 with a bearing interposed therebetween, whereby the pitch control plate 85 rotates integrally with the rotor shaft 44 and the slider sleeve 87 independently of the slider ring 86. .

  A pair of bosses 822 provided at the tip of the pitch lever 82 are fitted into the groove portion 862 of the slider ring 86. As a result, the slider portion S moves up and down in conjunction with the vertical movement of the pitch lever 82.

  FIG. 5 is a side view showing the pitch angle changing operation of the rotor 43 by the pitch changing mechanism PC.

  When the servo motor 71 is driven in the CW direction in plan view, the second control rod 73 connected to the servo horn 711 rotates each control hub 72. Each control hub 72 pushes the first control rod 81 connected thereto to the distal end side of each arm 12. The pushed first control rod 81 lifts the pitch lever 82 via the pitch lever link 811. The lifted pitch lever 82 raises the slider ring 86 and the pitch control plate 85 integrated therewith. The raised pitch control plate 85 rotates the feathering hinge 88 via the pitch link 851, thereby increasing the angle of attack (pitch angle) of the blade 432.

  FIG. 5 shows the operation when the pitch angle of the rotor 43 is increased. However, if the servo motor 71 is driven in the CCW direction, the pitch angle of the rotor 43 is decreased through a process reverse to the above process. Become.

  Thus, the pitch changing mechanism PC of this example changes the pitch angle of each rotor 43 by collective pitch control (control to increase or decrease the pitch angle of all blades of one rotor simultaneously by the same amount), and the main rotor of the helicopter The cyclic pitch control that is generally performed in is not performed. In the pitch changing mechanism PC of this example, the structure related to the cyclic pitch control is removed from the pitch changing mechanism PC, thereby simplifying the pitch changing mechanism PC.

(Rotor drive mechanism)
FIG. 6 is a side sectional view showing the drive mechanism of the rotor 43. Hereinafter, the rotor drive mechanism of this example will be described with reference to FIGS. 4 and 6. In the description based on FIG. 6, the front end side (the arrow f side in FIG. 6) of the arm 12 is “front”, and the opposite side (the arrow r side in FIG. 6) is “rear”.

  As described above, in the multicopter 10 of this example, the motor 41 that is the driving source of each rotor 43 is disposed in the center frame 11, and these motors 41 have their output shafts 411 on the side of each arm 12. It is fixed to the motor mount 419 so as to face toward.

  One end (base end) of a shaft adapter 412, which is a cylindrical connection member, is attached to the output shaft 411 of the motor 41, and the power transmission member of the motor 41 is connected to the other end (tip end) of the shaft adapter 412. A certain drive shaft 42 is connected. The drive shaft 42 is a cylindrical rod body, and a drive gear 421 that is a bevel gear is attached to the front end portion thereof.

  The drive gear 421 is disposed in the rotor base 13. A driven gear 441 that is a bevel gear that meshes with the drive gear 421 is disposed at the lower end (base end) of the rotor shaft 44 that is rotatably supported by the support plate 132. Thereby, the output of the motor 41 is sequentially transmitted to the shaft adapter 412, the drive shaft 42, the drive gear 421, the driven gear 441, the rotor shaft 44, and the rotor hub 431, and the rotor 43 is rotated.

  As described above, as the weight of the tip of the multicopter increases, the posture of the multicopter becomes less stable due to the inertia of the arm tip, and the agility of the flight operation is impaired. In the multicopter 10 of this example, a motor 41 is arranged on the center frame 11 and the output of the motor 12 is transmitted to the rotor 43 via the drive shaft 42 to reduce the weight of the tip of the arm 12, thereby enabling the flight operation. Improves stability and agility.

  The power transmission member that transmits the output of the motor 41 to the rotor 43 is not limited to the drive shaft 42 of this example, and for example, a toothed belt may be employed. However, in that case, the output shaft 411 of the motor 41 needs to be arranged vertically (vertically) in the center frame 11, and the space efficiency in the center frame 11 is reduced. In the multicopter 10 of this example, by adopting the drive shaft 42, it is possible to arrange the motor 41 so that the output shaft 411 faces each arm 12 side. Space efficiency is increased.

(Functional configuration)
7 and 8 are block diagrams showing the functional configuration of the multicopter 10.

  The functions of the multicopter 10 are mainly the flight controller FC that is the control unit, the four rotors 43 and the motor 41, and the ESC 24 (Electric Speed) that is a motor drive circuit that controls the rotation speed (synonymous with the rotation speed) of the motor 41. Controller), a communication device 52 that communicates with the operator (operator terminal 51), the above-described pitch change mechanism PC, and a battery 60 that supplies electric power thereto.

  The flight controller FC has a control device 20 which is a microcontroller. The control device 20 includes a CPU 21 that is a central processing unit, and a memory 22 that includes a storage device such as a RAM, a ROM, and a flash memory.

  The flight controller FC further includes a flight control sensor group 30 including an IMU 31 (Inertial Measurement Unit), a GPS receiver 32, an atmospheric pressure sensor 33, and an electronic compass 34, which are connected to the control device 20. Has been.

  The IMU 31 is a sensor that detects the inclination of the multicopter 10 and mainly includes a triaxial acceleration sensor and a triaxial angular velocity sensor. The atmospheric pressure sensor 33 is an altitude sensor that obtains the altitude (altitude) of the multicopter 10 from the detected atmospheric pressure value. The electronic compass 34 is a sensor that detects the azimuth of the nose of the multicopter 10. A triaxial geomagnetic sensor is used for the electronic compass 34 of this example. The GPS receiver 32 is precisely a navigation satellite system (NSS) receiver. The GPS receiver 32 obtains the current longitude and latitude values from the Global Navigation Satellite System (GNSS) or the Regional Navigational Satellite System (RNSS).

  The flight controller FC uses the flight control sensor group 30 to acquire position information of its own aircraft including the inclination and rotation of the aircraft, as well as the longitude and latitude of the aircraft during flight, and the azimuth angle of the nose.

  The control device 20 has a flight control program FS that controls the attitude and basic flight operation of the multicopter 10 during flight. The flight control program FS adjusts the rotational speed of each rotor 43 based on the information acquired from the flight control sensor group 30 and causes the multicopter 10 to fly while correcting the posture and position disturbance of the airframe.

  The control device 20 further includes an autonomous flight program AP that is a program for autonomously flying the multicopter 10. In the memory 22 of the control device 20, a flight plan FP, which is a parameter in which the longitude and latitude of the route on which the multicopter 10 is made to fly, the altitude and the speed during the flight, etc., is designated is registered. The autonomous flight program AP causes the multicopter 10 to fly autonomously in accordance with the flight plan FP using an instruction from the operator terminal 51 as a start condition.

  The operator terminal 51 may be a radio control transmitter or a device generally called GCS (Ground Control Station) in the unmanned aerial vehicle field. In addition, the operator terminal 51 may be a terminal of an operation management system (UTM: UAV Traffic Management) that controls many multicopters 10.

  As long as the communication device 52 and the operator terminal 51 of the multicopter 10 can transmit and receive control signals and data, their specific communication methods and protocols are not limited. For example, Wi-Fi (Wireless Fidelity), which is a two-way communication, is used for uploading the flight plan FP to the multicopter 10 and receiving telemetry data, and the control signal at the time of manual control is a frequency hopping method in the 2.4 GHz band. A configuration in which a PCM (pulse code modulation) signal is transmitted can be considered. In addition, the multicopter 10 and the operator terminal 51 may be connected via a mobile communication network such as 3G, LTE (Long Term Evolution), or WiMAX (Worldwide Interoperability for Microwave Access). By doing so, the operator (operator terminal 51) can control the multicopter 10 from anywhere within the service area of the mobile communication network.

  In addition, although the flight control sensor group 30 of this example is set as the structure for outdoor, the multicopter 10 may fly indoors. For example, a beacon that transmits a radio signal is placed at a predetermined location in a facility, and the relative distance between the multicopter 10 and each beacon is measured from the radio wave intensity of the signal received from these beacons, It is conceivable to specify the position of the multicopter 10. Alternatively, it is also possible to mount a camera or an optical flow sensor separately on the multicopter 10 and specify the current position in the facility by image recognition. Similarly, a distance measuring sensor using laser, infrared rays, ultrasonic waves, or the like is separately mounted, the distance between the floor surface (or ceiling surface) or wall surface in the facility and the multicopter 10 is measured, and the multicopter in the facility is measured. Ten positions may be specified.

  The multicopter 10 of this example uses only the pitch changing mechanism PC to adjust the pitch angle of the rotor 43 in a unified manner, and the movement in the air is performed exclusively by controlling the rotational speed of each rotor 43. In other words, the pitch changing mechanism PC is, so to speak, capable of changing the pitch angle of the fixed pitch propeller without replacing the propeller, and has a different use and technical idea from a general pitch changing mechanism. . The pitch change mechanism PC of the present example is not only simplified in structure by narrowing down its functions and applications, but also by moving the air in the air exclusively by controlling the rotational speed of the rotor 43, It is possible to adopt the flight controller without modification. Thereby, the multicopter 10 eliminates the troublesome adjustment of the optimum pitch of the propeller without complicating and destabilizing the airframe structure and the flight program.

  Note that the pitch angle changing operation in the multicopter 10 of the present example assumes that the operator manually issues an instruction to the pitch changing mechanism PC based on his / her own judgment. For example, as shown in FIG. A pitch adjustment program PP for automatically controlling the pitch changing mechanism PC may be separately provided.

  The pitch adjustment program PP can automatically control the pitch change mechanism PC according to a predetermined condition in addition to transferring the control signal of the pitch change mechanism PC received from the communication device 52 to the pitch change mechanism PC. . Even in this case, since the movement in the air is performed exclusively by the rotational speed control of each rotor 43, it is not necessary to modify the existing flight program such as the flight control program FS. In the example of FIG. 8, the pitch adjustment program PP is installed in the control device 20 of the flight controller FC, so that the output values of the flight control sensor group 30 and the flight control program FS provided in the flight controller FC are changed to those of the pitch change mechanism PC. Although it is also used for control, a control device or sensors dedicated to the pitch adjustment program PP may be prepared separately. By doing so, the pitch adjustment program PP can be made completely independent from the flight controller FC.

  The pitch changing mechanism PC can simultaneously change the pitch angle of the rotor 43 by the same amount while keeping all the pitch angles of the rotor 43 at the same angle. By applying this function, the pitch adjustment program PP can realize the following automatic control.

  For example, the pitch adjustment program PP monitors the output values of the flight control sensor group 30 and the flight control program FS, and when the rotational speed of the rotor 43 falls below a predetermined threshold and the posture control may be disturbed, the pitch adjustment program PP It is conceivable to prevent the rotor 43 from stalling by temporarily reducing the pitch angle to lower the thrust with respect to the rotational speed of each rotor 43 and maintaining the rotational speed of each rotor 43.

  As another example, it is conceivable that the pitch adjustment program PP automatically keeps the pitch angle large enough that the rotational speed of the rotor 43 does not fall below a predetermined threshold. In order to increase the energy efficiency of the rotor 43, it is desirable to rotate the rotor 43 at a low speed, but this also means that the rotor 43 becomes vulnerable to the rising airflow at the same time. The pitch adjustment program PP monitors the rotational speed of the rotor 43 and automatically increases the pitch angle within a safe range, so that the energy efficiency of the rotor 43 can be enhanced while avoiding the stall of the rotor 43. The rotation speed of the rotor 43 can be calculated by monitoring a control signal such as a PWM (Pulse Width Modulation) signal input to the ESC 24. In addition to this, a sensor for directly measuring the rotation speed of the rotor 43 may be separately mounted, or a current sensor may be attached to the motor 41.

  As mentioned above, although embodiment of this invention was described, the range of this invention is not limited to this, A various change can be added in the range which does not deviate from the main point of invention.

10: Multicopter (unmanned aerial vehicle), 11: Center frame, 12: Arm, 13: Rotor base, FC: Flight controller, PP: Pitch adjustment program, 24: ESC, 41: Motor, 411: Output shaft, 412: Shaft Adapter, 419: Motor mount, 42: Drive shaft, 421: Drive gear (bevel gear), 43: Rotor, 431: Rotor hub, 432: Blade, 44: Rotor shaft, 441: Drive gear (bevel gear), 51 : Operator terminal, 52: communication device, PC: pitch change mechanism, 71: servo motor, 711: servo horn, 72: control hub, 73: second control rod, 81: first control rod, 811: pitch lever link, 82: Pitch lever (pitch leveler), 821: Pick Lever base, 822: boss, S: slider member, 85: pitch control plate, 851: pitch link, 86: slider ring, 861: flange, 862: groove, 863: bearing, 87: slider sleeve, 88: feathering Hinge

Claims (8)

An unmanned aerial vehicle having a plurality of rotors,
A pitch changing mechanism for changing a pitch angle of the plurality of rotors;
A speed controller for controlling the rotational speed of each of the rotors;
With
The pitch changing mechanism has one or more motors that are driving sources of the pitch changing mechanism,
The number of motors is less than the number of rotors,
The pitch changing mechanism changes the pitch angle of the plurality of rotors simultaneously by the same amount while keeping all the pitch angles of the rotors at the same angle.
An unmanned aerial vehicle characterized in that movement in the air is performed by controlling the rotational speed of each rotor. The unmanned aerial vehicle according to claim 1 , wherein the pitch changing mechanism changes all pitch angles of the plurality of rotors by a single motor that is a drive source of the pitch changing mechanism.   2. The unmanned aerial vehicle according to claim 1, wherein the pitch changing mechanism changes a pitch angle of each rotor by collective pitch control and does not perform cyclic pitch control on the plurality of rotors. A center frame that is the center of the aircraft,
A plurality of arms extending radially from the center frame in plan view,
Each of the plurality of rotors is supported by the arm,
Each rotor is
A blade that is a rotor blade,
A rotor hub to which the blade is connected,
The rotor hub is coupled to a rotor shaft that is a rotating shaft,
The pitch changing mechanism is provided for each rotor.
A slider member connected to the blade by a pitch link which is a link member;
A pitch leveler that is a mechanism for raising and lowering the slider member along the rotor shaft;
A first control rod that is a rod-shaped link member for operating the pitch leveler,
The first control rod is disposed along the arms from the center frame,
2. The unmanned aerial vehicle according to claim 1, wherein the pitch changing mechanism changes the pitch angle of each rotor by simultaneously advancing and retracting all the first control rods along the respective arms by the same amount. A control hub, which is a hub member that rotates horizontally with the output of the motor, is disposed on the center frame,
The unmanned aerial vehicle according to claim 4 , wherein a base end portion of each of the first control rods is connected to the control hub. Comprising four rotors,
In the center of the center frame, a servo horn that is an output part of the motor is arranged,
In the center frame, a pair of the control hubs are arranged at positions that are point-symmetric with respect to the rotation center of the servo horn when the center frame is viewed in plan,
The servo horn and each control hub are connected by a second control rod that is a rod-shaped link member,
Two first control rods are connected to each control hub,
5. The unmanned aerial vehicle according to claim 4 , wherein the pair of control hubs simultaneously advance and retract the four first control rods along the arms by the rotation of the servo horn. A pitch adjustment program which is a program for automatically controlling the pitch change mechanism;
2. The unmanned aerial vehicle according to claim 1, wherein the pitch adjustment program automatically reduces the pitch angle of the plurality of rotors when a rotational speed of each of the rotors falls below a predetermined threshold value. A pitch adjustment program which is a program for automatically controlling the pitch change mechanism;
2. The unmanned aerial vehicle according to claim 1, wherein the pitch adjustment program automatically keeps the pitch angles of the plurality of rotors large so that a rotation speed of each of the rotors does not fall below a predetermined threshold.

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