Propeller gimbal and drone having same

Abstract

A propeller gimbal according to the present invention comprises: a lower frame and an upper frame spaced apart from each other in the vertical direction (z); a tilting shaft connection part that is formed in the middle of the lower frame in parallel to an x direction and is connected to a tilting shaft installed in a drone body; a movable shaft connection part that is formed in the middle of the upper frame in parallel to the tilting shaft connection part and is connected to a movable shaft installed in the drone body; a motor mount arm that is supported by the upper frame so as to be able to rotate about an axis parallel to a y direction; and a propeller assembly in which a propeller and a motor for rotating the propeller are arranged in a reverse direction so that the propeller is located below the motor when viewed in the vertical direction (z), wherein the propeller rotates about an axis parallel to the vertical direction (z), and the aerodynamic center (AC) of the propeller assembly is located on an extension line of the tilting shaft.

Description

Propeller gimbal and drone having the same

[0001] The present invention relates to a propeller gimbal and a drone having the same.

[0002]

[0003] A drone, also known as a multirotor or multifan aircraft, is a type of helicopter, typically equipped with three or more rotors. Compared to traditional single-rotor helicopters, drones offer the advantage of flight by varying the torque and speed of the rotors, as well as ease of maintenance and operation. These advantages, coupled with rapid advancements in electronic technology, have led to a rapid expansion of the applications of multirotor aircraft. While large, military-grade unmanned aerial vehicles (UAVs) were predominant in the past, smaller UAVs are now being produced for civilian use. Their applications are also expanding, ranging from videography to cargo transport.

[0004] Among the various types of small unmanned aerial vehicles (UAVs), multi-rotor aircraft, known as quadrotors, offer numerous advantages over other aircraft. The most significant advantage is their extremely simple mechanical mechanisms. Quadrotors eliminate the need for pre-flight trimming, generate minimal mechanical vibration, and have a low risk of component failure due to fatigue. Furthermore, their simple design makes them easy to model mathematically, making them ideal for automated flight. Unlike other small aircraft that require extensive training to control, quadrotors are easy to pilot, even for beginners. Furthermore, their use of multiple small propellers makes them relatively safe, even for those unfamiliar with piloting or maintenance. This means anyone can easily pilot, maintain, and service quadrotors, even without specialized knowledge or extensive training. Thanks to these advantages, quadrotors are gradually gaining traction among small civilian UAVs.

[0005] Many researchers have already conducted research on the control and guidance of quadrotors. First, in the field of control, to effectively address the nonlinear characteristics of a quadrotor model, techniques such as backstepping and sliding mode have been used to directly control nonlinear systems. Other attempts have also been made to linearize the quadrotor model and then control it using feedback linearization. Furthermore, in the field of guidance, it has become possible to perform flips, rotating the quadrotor body 360 degrees or more in one direction, perform rapid maneuvers such as following a specific trajectory and attitude, and even perform sophisticated maneuvers such as passing a ball back and forth.

[0006] Thanks to the contributions of numerous researchers, we've reached a point where we can precisely control and guide multi-rotor aircraft, such as quadrotors. However, there are still areas for functional improvement. Recalling that the precise position and attitude of an aircraft in three-dimensional space are expressed by six variables, a multi-rotor aircraft system ultimately becomes an under-actuated system, with the input dimensionality smaller than the output dimensionality. This limitation limits the control and guidance of multi-rotor aircraft. For example, to accelerate a multi-rotor aircraft forward, its main body must be tilted forward. If a multi-rotor aircraft is tilted backward, forward acceleration will never occur. This means that the attitude and acceleration of a multi-rotor aircraft cannot be completely independent.

[0007] Accordingly, when a camera is attached to the body of a multi-rotor aircraft to photograph an object, the body of the multi-rotor aircraft tilts when the multi-rotor aircraft changes direction, causing the camera's shooting direction to deviate from the subject. In addition, since the entire multi-rotor aircraft must tilt when changing direction, the responsiveness is relatively low, making rapid maneuvers difficult. For this reason, a separate device is used to maintain the camera according to the change in the body's angle, but this causes an increase in parts and cost, and it also increases weight, which shortens the battery life. In addition, because such a camera connection device is vulnerable to vibration, a separate absorption means is sometimes installed, which also has the disadvantage of making the device more complex.

[0008] * Related prior art

[0009] Korean Patent Publication No. 10-2017-0061941 (published on June 7, 2017)

[0010] Korean Patent No. 10-1692315 (registered on December 28, 2016)

[0011] Korean Patent No. 10-2331583 (registered on November 23, 2021)

[0012]

[0013] The purpose of the present invention is to propose a propeller gimbal and a drone having the same that can secure dynamic stability by maintaining the center of the propeller at one point during gimbal operation.

[0014] The tasks of the present invention are not limited to those mentioned above, and other technical tasks can be clearly understood by those skilled in the art from the description below.

[0015]

[0016] A propeller gimbal according to the present invention comprises: a lower frame and an upper frame spaced apart in the vertical direction (z); a tilting shaft connection portion formed in the middle of the lower frame parallel to the x direction and connected to a tilting shaft installed in a drone body; a movable shaft connection portion formed in the middle of the upper frame parallel to the tilting shaft connection portion and connected to a movable shaft installed in the drone body; a motor mount arm rotatably supported about an axis parallel to the y direction on the upper frame; and a propeller assembly in which a propeller and a motor for rotating the propeller are arranged in reverse directions so that the propeller is positioned below the motor when viewed in the vertical direction (z), the propeller is arranged to rotate about an axis parallel to the vertical direction (z), and an aerodynamic center (AC) of the propeller assembly is formed to be located on an extension of the tilting shaft.

[0017] As an example according to the present invention, the lower frame and the upper frame may be formed in a 'C' or 'O' shape when viewed in the vertical direction (z).

[0018] As an example according to the present invention, the propeller gimbal may further include a linker whose one end is pin-connected to the tilting shaft connection portion and whose other end is pin-connected to the movable shaft connection portion.

[0019] As an example according to the present invention, the motor mount arm may include a pair of shafts extending inwardly from both ends of the upper frame along the y-direction and being rotatably supported about the y-direction with respect to the upper frame; a mount plate installed at the inner ends of the pair of shafts and to which the propeller assembly is fixed; and a pair of arm portions having one end coupled to the outer end of the pair of shafts and the other end rotatably connected to the lower frame, such that when the upper frame deviates from a neutral position with respect to the lower frame when viewed in the up-down direction (z), the pair of shafts are rotated about the y-direction in response to the deviation angle, thereby tilting the propeller assembly with respect to the upper frame.

[0020] As an example according to the present invention, a journal is formed on the outer end of the pair of shafts, and the journal can be rotatably connected to a pin connection formed in the upper frame.

[0021] As an example according to the present invention, the aerodynamic center of the propeller assembly may be located on an extension line of a pair of fins through which the pair of female parts are connected to the lower frame.

[0022] A drone according to the present invention comprises: a drone body; a tilting shaft extending from the drone body in the x-direction and pivoted relative to the drone body so as to be rotatable about the x-direction; a movable shaft extending in the x-direction parallel to the tilting shaft and arranged to be spaced apart in the vertical direction (z) with respect to the tilting shaft in a neutral state; a lower frame including a tilting shaft connecting portion for connecting to the tilting shaft; an upper frame spaced apart from the lower frame in the vertical direction (z) and including a movable shaft connecting portion for connecting to the movable shaft; a motor mount arm supported by the upper frame so as to be rotatable about an axis parallel to the y-direction; And the propeller and the motor that rotates the propeller are arranged in reverse so that the propeller is located below the motor when viewed in the vertical direction (z), the propeller is arranged to rotate around an axis parallel to the vertical direction (z), and the aerodynamic center (AC) of the propeller assembly is formed to be located on an extension line of the tilting shaft.

[0023]

[0024] According to the propeller gimbal according to the present invention, the propeller assembly is positioned on the upper frame, and the aerodynamic center of the propeller assembly is on the extension line of the tilting shaft connection, so that even if the propeller gimbal rotates, the center of the propeller is fixed to one point, thereby greatly improving dynamic stability.

[0025] In addition, according to the propeller gimbal and the drone having the same according to the present invention, a plurality of propeller gimbals can be configured to be independently tilted about the x-axis and the y-axis, and the main body can maintain the same posture or be set to a specific desired posture even when turning, changing posture, or changing speed, thereby enabling implementation of various flight modes.

[0026]

[0027] FIG. 1 is a perspective view of a propeller gimbal according to an example of the present invention.

[0028] Figure 2 is an exploded perspective view of the propeller gimbal of Figure 1.

[0029] Figure 3 is a perspective view of a propeller gimbal according to another example of the present invention.

[0030] FIG. 4 is a perspective view of an exemplary drone having a propeller gimbal in accordance with the present invention.

[0031] Figure 5 is a perspective view showing the drone of Figure 4 with the main body cover removed.

[0032] Fig. 6 is an exemplary operating state diagram showing various modes of the propeller gimbal applied to the drone of Fig. 4.

[0033] Figure 7 is an operating state diagram showing the propeller gimbal related to the present invention in two modes compared to the prior art.

[0034]

[0035] Hereinafter, a propeller gimbal and a drone having the same according to the present invention will be described in detail with reference to the attached drawings. The terms used in this specification and claims are not limited to their dictionary meanings, but are appropriately defined and understood to best describe the present invention.

[0036] In this specification and claims, the term 'propeller gimbal' is used to mean a device that has a rotating blade, i.e. a propeller, to obtain propulsion or lift, and also has a function of compensating for the shaking of an object of the 'gimbal' through a supporting mechanism structure and control.

[0037] Fig. 1 is an exemplary diagram illustrating a propeller gimbal according to the present invention. Referring to Fig. 1, the propeller gimbal (100) comprises a lower frame (110) and an upper frame (120) that are spaced apart from each other approximately vertically. The lower frame (110) and the upper frame (120) may be formed in an approximately 'C' shape when viewed from above to provide a rotational space for a propeller assembly (150) disposed therein.

[0038] The lower frame (110) and the upper frame (120) have a connection structure for connecting to respective objects extending from the drone body. Specifically, as such connection structures, the lower frame (110) has a pivot shaft connection portion (111), and the upper frame (120) has a movable shaft connection portion (121). The objects to which the pivot shaft connection portion (111) is connected and the objects to which the movable shaft connection portion (121) is connected will be exemplarily described in FIG. 4 and below.

[0039] The lower frame (110) and the upper frame (120) may have similar shapes in terms of form, and are positioned so as to be spaced apart in the vertical direction (z direction) in a neutral state. While the lower frame (110) and the upper frame (120) are spaced apart in the vertical direction, the upper frame (120) is allowed to move in a specific direction with respect to the lower frame (110) by the linker (130) and the motor mount arm (140). For example, assuming that the lower frame (110) is fixed, when a force that pushes or pulls the upper frame (120) in the x direction is applied through the movable shaft connection (121), the upper frame (120) moves in parallel with the lower frame (110) while being restrained by the linker (130) and the motor mount arm (140). When viewed in the vertical direction (z), when the upper frame (120) deviates from the neutral position of the lower frame (110), the rotation axis of the propeller assembly (150) changes at a different angle with respect to the upper frame (120) or the lower frame (110) in response to the deviation angle. This enables steering (e.g., rolling) when the drone moves. As another example, when the lower frame (110) is pivoted with respect to the drone body through the tilting shaft connection (111), an external force in the y direction applied to the movable shaft connection (121) acts as a torque that rotates the propeller gimbal (100) about the rotation axis parallel to the x direction passing through the tilting shaft connection (111). This enables other steering (e.g., pitching) when the drone moves. The transmission of force in the x-direction or the transmission of force in the y-direction to this movable shaft connection (121) can be independent, and accordingly, the propeller gimbal (100) can have various degrees of freedom.

[0040] Fig. 2 shows the disassembled state of the propeller gimbal (100) of Fig. 1. According to Fig. 2, the motor mount arm (140) has a pair of shafts (141) that extend inwardly in the y-direction from both ends of the upper frame (120) and are rotatably supported about the y-direction with respect to the upper frame (120). A mount plate (142) for fixing a propeller assembly (150) is installed on the inner ends of the pair of shafts (141). An arm portion (144) is coupled to the outer ends of the pair of shafts (141). One end of the arm portion (144) is coupled to a journal (143) formed on the outer end of the shaft (141), and the other end is coupled to a pin connection portion (112) of the lower frame (110) and a pin (145). The journal (143) is also pin-connected to the pin connection (122) of the upper frame (120), thereby allowing rotation around the y direction.

[0041] The propeller assembly (150) includes a propeller (151) and a motor (152) that rotates the propeller (151), and the propeller (151) and the motor (152) are arranged in reverse so that the propeller (151) is positioned below the motor (152) when viewed in the vertical direction (z). The propeller (151) is arranged to rotate around an axis parallel to the vertical direction (z). The motor (152) can be fastened to the mount plate (142) by a screw (146).

[0042] The placement of the aerodynamic center (AC) of the propeller assembly (150), which is the main focus of the present disclosure, is arranged so as to be placed on an imaginary extension line extending in the x direction from the tilting shaft connection part (111). In addition, by placing the aerodynamic center (AC) of the propeller assembly (150) on an imaginary extension line connecting the pin (145) of the motor mount arm (140) and another pin (145) or an imaginary extension line connecting the pin connection part (112) of the lower frame (110) and another pin connection part (112), the dynamic stability can be improved even when the propeller (151) rotates during the operation of the propeller gimbal (100).

[0043] Fig. 3 illustrates a propeller gimbal (100') according to another example of the present invention. In this example, unlike Fig. 1 where the lower frame (110) and the upper frame (120) are formed in a 'C' shape, the lower frame (110') and the upper frame (120') are formed in an 'O' shape. In this case, a method of assembling 'C'-shaped frame pieces to complete the lower frame (110') and the upper frame (120') to form an 'O' shape is also possible.

[0044] FIG. 4 is a perspective view of an exemplary drone (200) having a propeller gimbal related to the present invention, and FIG. 5 is a perspective view showing the drone (200) of FIG. 4 with the main body cover removed.

[0045] As shown in these drawings, the drone (200) has a drone body (210) positioned in the center of the previously described propeller gimbals (100) installed at four predetermined locations. In order for each propeller gimbal (100) to be connected to the drone body (210), a pair of tilting shafts (220, 221) extending left and right in the x-direction and a movable shaft (230, 231) spaced apart from the upper portions of the tilting shafts (220, 221) when viewed in the vertical direction (z) are installed on the drone body (210). The movable shafts (230, 231) also extend left and right in the x-direction in parallel with the tilting shafts (220, 221). The tilting shaft (220, 221) is an object connected to the tilting shaft connection (111) of the propeller gimbal (100) described above, and the movable shaft (230, 231) is an object connected to the movable shaft connection (121) of the propeller gimbal (100). The movable shaft (230, 231) transmits the force in the x direction to the upper frame (120) of each propeller gimbal (100) by the first drive motor (240) and the first transmission shaft (241). In this case, the propeller assembly (150) is tilted with respect to the upper frame (120) and the drone body (210) in the y direction. In addition, the movable shafts (230, 231) can transmit the force in the y direction to the upper frame (120) of each propeller gimbal (100) by means of the second drive motor (250) and the second transmission shaft (251). In this case, the propeller assembly (150) is tilted with respect to the tilting shafts (220, 221) and the drone body (210) with respect to the x direction. This is specifically illustrated in FIG. 6.

[0046] As shown in Fig. 6, the aerodynamic center (AC) of the propeller assembly (150) is located on the extension line (x) of the tilting shaft (220) (a). In this state, as shown in (b), when an x-direction force is transmitted to the movable shaft (230), the upper frame (120) tilts the propeller assembly (150) around the y-direction by the motor mount arm (140) (roll rotation). If, as shown in (c), an external force in the y-direction is transmitted to the movable shaft (230) and applied to the upper frame (120), the propeller assembly (150) tilts around the extension line (x) of the tilting shaft (220) (pitch rotation). During roll rotation or pitch rotation in this way, the aerodynamic center (AC) of the propeller assembly (150) is located on the extension line of the tilting shaft (220) and the extension line of the pin connection part (112) of the lower frame (110), thereby ensuring dynamic stability.

[0047] Figure 7 shows a comparison of the propeller gimbal according to the present invention with the prior art in two modes. (a) and (c) show pitch rotation situations, and (b) and (d) show roll rotation situations, respectively.

[0048] According to the prior art (a, b), the propeller assembly (50) is installed on the lower frame (10), the propeller is positioned on the upper part of the motor, the center of gravity (CM) of the propeller assembly (50) is positioned on an extension of the tilting shaft connection portion (11), and the aerodynamic center (AC) of the propeller assembly (50) is positioned approximately near the upper frame (20). In this case, when the propeller assembly (50) is tilted, the influence of the aerodynamic center (AC) becomes greater than that of the center of gravity (CM), which may generate unintended torque and adversely affect the attitude control of the drone. On the other hand, according to the techniques (c, d) according to the present invention, the aerodynamic center (AC) of the propeller assembly (150) is positioned on an extension of the tilting shaft connection portion (111), so that almost no torque is generated due to the tilting of the propeller assembly (150).

[0049] The propeller gimbal and drone having the same described above are not limited to the configurations and methods of the described embodiments. The above embodiments may be selectively combined in whole or in part to allow for various modifications to be made into equivalent, replaceable components.

Claims

1. Lower frame and upper frame spaced apart in the vertical direction (z); A tilting shaft connecting portion formed parallel to the x-direction in the middle of the above-mentioned lower frame and connected to a tilting shaft installed in the drone body; A movable shaft connection portion formed parallel to the tilting shaft connection portion in the middle of the upper frame and connected to the movable shaft installed in the drone body; A motor mount arm that is rotatably supported about an axis parallel to the y direction on the upper frame; and A propeller gimbal including a propeller assembly, wherein the propeller and the motor that rotates the propeller are arranged in reverse directions so that the propeller is located below the motor when viewed in the vertical direction (z), the propeller is arranged to rotate around an axis parallel to the vertical direction (z), and an aerodynamic center (AC) of the propeller assembly is formed to be located on an extension of the tilting shaft.

2. In paragraph 1, A propeller gimbal in which the lower frame and the upper frame are formed in a 'C' or 'O' shape when viewed in the upper-lower direction (z).

3. In paragraph 1, A propeller gimbal further comprising a linker, one end of which is pin-connected to the tilting shaft connection portion and the other end of which is pin-connected to the movable shaft connection portion.

4. In paragraph 1, The above motor mount arm is, A pair of shafts extending inwardly along the y direction from both ends of the upper frame and being rotatably supported about the y direction with respect to the upper frame; A mount plate installed on the inner end of the above pair of shafts and to which the propeller assembly is fixed; and A propeller gimbal comprising a pair of arm parts, one end of which is connected to the outer ends of the pair of shafts and the other end of which is rotatably connected to the lower frame, such that when the upper frame deviates from the neutral position with respect to the lower frame when viewed in the up-down direction (z), the pair of shafts are rotated about the y direction in response to the deviation angle, thereby tilting the propeller assembly with respect to the upper frame.

5. In paragraph 4, A propeller gimbal in which a journal is formed on the outer end of the above pair of shafts, and the journal is rotatably connected to a pin connection formed in the upper frame.

6. In paragraph 4, A propeller gimbal, wherein the aerodynamic center of the propeller assembly is located on an extension line of a pair of fins through which the pair of female parts are connected to the lower frame.

7. Drone body; A tilting shaft extending in the x-direction from the drone body and pivoted relative to the drone body so as to be able to rotate around the x-direction; A movable shaft extending in the x direction parallel to the tilting shaft and arranged to be spaced apart in the vertical direction (z) with respect to the tilting shaft in a neutral state; A lower frame including a tilting shaft connecting portion for connecting to the above tilting shaft; An upper frame spaced apart from the lower frame in the vertical direction (z) and including a movable shaft connecting portion for connecting to the movable shaft; A motor mount arm that is rotatably supported about an axis parallel to the y direction on the upper frame; and A drone including a propeller assembly, wherein the propeller and the motor that rotates the propeller are arranged in reverse directions so that the propeller is located below the motor when viewed in the vertical direction (z), the propeller is arranged to rotate around an axis parallel to the vertical direction (z), and an aerodynamic center (AC) of the propeller assembly is formed to be located on an extension of the tilting shaft.

8. In paragraph 7, A drone in which the lower frame and the upper frame are formed in a 'C' or 'O' shape when viewed in the upper-lower direction (z).

9. In paragraph 7, A drone further comprising a linker, one end of which is pin-connected to the tilting shaft connection portion, and the other end of which is pin-connected to the movable shaft connection portion.

10. In paragraph 7, The above motor mount arm is, A pair of shafts extending inwardly along the y direction from both ends of the upper frame and being rotatably supported about the y direction with respect to the upper frame; A mount plate installed on the inner end of the above pair of shafts and to which the propeller assembly is fixed; and A drone including a pair of arm parts, one end of which is connected to the outer ends of the pair of shafts and the other end of which is rotatably connected to the lower frame, such that when the upper frame deviates from the neutral position with respect to the lower frame when viewed in the up-down direction (z), the pair of shafts are rotated about the y direction in response to the deviation angle, thereby tilting the propeller assembly with respect to the upper frame.

11. In paragraph 10, A drone in which a journal is formed on the outer end of the pair of shafts, and the journal is rotatably connected to a pin connection formed in the upper frame.

12. In paragraph 10, A drone wherein the aerodynamic center of the propeller assembly is located on an extension line of a pair of fins through which the pair of female parts are connected to the lower frame.

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