WO2019120214A1

WO2019120214A1 - Two-axis gimbal system

Info

Publication number: WO2019120214A1
Application number: PCT/CN2018/122020
Authority: WO
Inventors: Zhaozhe WANG; Qiong Liu
Original assignee: Hangzhou Zero Zero Technology Co., Ltd.
Priority date: 2017-12-19
Filing date: 2018-12-19
Publication date: 2019-06-27

Abstract

A two-axis gimbal system (10) includes a camera module (12) and a pitch axis motor assembly (14) including a stator part (16) and a rotary part (18) wherein the stator part (16) is coupled to the camera module (12) along a pitch axis (P) and the pitch axis motor assembly (14) drives the camera module (12) to pivot around the pitch axis (P). The system (10) also includes a roll axis motor assembly (20) including a second stator part (22) and a second rotary part (24). The system (10) further includes a first bracket (26) having two ends (46,48), wherein the first end (46) is coupled to the stator part (16) of the pitch axis motor assembly (14) along a roll axis (R) and the second end (48) is coupled to the second rotary part (24) of the roll axis motor assembly (20) such that the first bracket (26) is driven by the roll axis motor assembly (20) to pivot around the roll axis (R). The system (10) also includes a second bracket (28) and a control board assembly (30).

Description

TWO-AXIS GIMBAL SYSTEM

FIELD OF THE DISCLOSURE

The present disclosure relates generally to a two-axis gimbal system. More specifically, the present disclosure relates to a two-axis gimbal system that includes a pitch axis motor assembly to pivot a camera module around a pitch axis and a roll axis motor assembly to pivot the camera module around a roll axis.

BACKGROUND

Unmanned aerial vehicles or drones are aerial vehicles without a human operator or pilot aboard that may be used, for example, to take images from a high altitude. Drones tend to be difficult to control, as the drone has multiple degrees of freedom including translational motion (such as longitudinal, lateral, and vertical) and rotational motion (such as pitch, roll, and yaw) . Translational motion typically changes the position of the drone, and rotational motion typically changes the orientation of the drone. For drones that are lifted or propelled using four rotors, which are often referred to as quadrotor, two rotational motions are coupled with two translational motions (such as pitch-longitudinal motion and roll-lateral motion) , resulting in a total of four degrees of freedom (e.g., pitch-longitudinal, roll-lateral, vertical, and yaw) .

Typically, the position and/or orientation of the drone is controlled remotely, such as with a hand-held device or controller, a mobile computing device including smartphones and tablet computers. However, control of the orientation and/or movement of the drone can be difficult when the drone has an onboard camera. These drones, which may be referred to as camera drones or camera UAVs, may be used by the operator to take a photograph of himself/herself (i.e., a selfie) , agriculture monitoring, real-estate advertisement, recording of sporting events, property management, and/or geographical survey. The camera is typically mounted on a multi-degree rotor or gimbal, and the pointing direction (orientation) of the camera is free to rotate independently relative to the position and/or orientation of the drone.

To ease the operation burden on the operator, many drone and gimbals have self-stabilizing features, which are typically controlled by onboard accelerometers or gyroscopes and associated software programs or logic. The self-stabilizing features of the drone continuously adjust the motor so that the drone stays at the target position when the drone is subjected to external disturbance (s) , such as wind and impact by/with other objects. Similarly, self-stabilizing features of the gimbal continuously adjust the rotor so that the gimbal returns to the target orientation when the gimbal is subjected to the external disturbance (s) . With the self-stabilizing feature, the drone/gimbal can remain at the target position/orientation, even with no input or command from the operator. Nevertheless, such systems tend to have complicated line routings which take up space and add unneeded weight to the system. Moreover, in such systems, the load center of gravity of the camera is usually along one/more gimbal motor pivot axis (axes) . As a result, the power consumption of the gimbal at a normal position increases since the motors must continue to generate torque to counteract residual torque of the cables attached to the camera. The present disclosure is aimed at solving the problems identified above.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of the present disclosure will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings. It is to be understood that the drawings are purely illustrative and are not necessarily drawn to scale.

Figure 1 is first perspective view of one embodiment of a two-axis gimbal system;

Figure 2 is an exploded perspective view of one embodiment of a two-axis gimbal system;

Figure 3 is a perspective view of portions of a two-axis gimbal system including a control module and a second bracket;

Figure 4 is a top cut away view of one embodiment of a camera module coupled to a pitch axis motor and including a coaxial cable connecting the camera module to the motor;

Figure 5 is a second top cut away view of an embodiment of a camera module coupled to a pitch axis motor and including a coaxial cable emerging from the camera module;

Figure 6A is an exploded view of one embodiment of the first bracket and the pitch axis motor;

Figure 6B is a perspective view of the first bracket and the pitch axis motor after assembly;

Figure 6C is an exploded perspective view of the camera module rotated 90 degrees and including a rear cover;

Figure 6D is a perspective view of Figure 6C wherein the rear cover is coupled to the camera module;

Figure 6E is an exploded perspective view of a gimbal system that includes a roll arm cover;

Figure 6F is a perspective view of Figure 6E wherein the roll arm cover is coupled to a side of the gimbal system;

Figure 7A is an exploded perspective view of a gimbal system that includes a yaw arm assembly and a flexible printed circuit; and

Figure 7B is a perspective view of Figure 7A wherein the flexible printed circuit is folded and fixed on a back of the yaw arm assembly.

DETAILED DESCRIPTION

With reference to the drawings and in operation, an aerial device (not shown in Figures) and a two-axis gimbal system 10 for the aerial device are described in detail below.

Aerial Device

The aerial device may be a drone or unmanned aircraft. In one embodiment, the aerial device is a rotorcraft, such as a quadcopter, helicopter, cyclocopter, and the like. In alternative embodiments, the aerial device may be a fixed-wing aircraft, an aerostat, or any other suitable aircraft. The aerial device is generally configured to fly within a physical space and, in certain embodiments, the aerial device is further designed to capture images (such as photographs and/or video) , and stream the images in near-real time to a remote device. In another embodiment, the aerial device is designed to capture and stream audio to a remote device. The aerial device may be designed to perform a variety of other functions, such as surveillance for industry, for monitoring weather conditions, for border patrols, for military operations, etc.

The aerial device may have a body or fuselage and a control interface disposed on the body. The control interface provides a control platform enabling the operator to control certain operations of the aerial device without direct or physical interaction with a remote device. The body of the aerial device mechanically protects and/or retains internal components of the aerial device. In an embodiment, the body substantially encapsulates at least a communication system, a power supply, and a processing system. The body may have any suitable configuration, size, and/or shape. In an embodiment, the body has a platform and/or a housing. In an example, the body has a housing for carrying or supporting at least the communication system, the power supply, and the processing system.

The aerial device may also include a communication system. The communication system functions to send and/or receive information from the remote device. The communication system may include wired or wireless communication systems. Non-limiting examples of communication systems include radios supporting long-range systems (e.g., Wi-Fi, cellular, WLAN, WiMAX, microwave, IR, radio frequency, etc. ) , short-range systems (e.g., BLE, BLE long range, NFC, ZigBee, RF, audio, optical, etc. ) , or any other suitable communication system. The communication system typically shares at least one system protocol (e.g., BLE, RF, etc. ) with the remote device. Alternatively, the communication system may communicate with the remote device via an intermediary communication system (e.g., a protocol translation system) .

The aerial device also includes a lift mechanism which functions to enable aerial system flight. More particularly, the lift mechanism functions to provide lift of the aerial device, and typically includes a set of rotors driven (individually or collectively) by one or more motors. Each rotor rotates about a corresponding rotor axis, defines a corresponding rotor plane normal to the rotor axis, and sweeps out a swept area on the rotor plane. The motors typically provide sufficient power to the rotors to enable aerial system flight, and may operate in two or more modes. At least one of the modes provides sufficient power for flight, and at least one of the modes provides less power than required for flight (e.g., providing zero power, providing 10%of a minimum flight power, etc. ) . The power provided by the motors affects the angular velocities at which the rotors rotate about their respective rotor axes. During aerial system flight, the set of rotors cooperatively or individually generate (e.g., by rotating about their rotor axes) substantially all (e.g., more than 99%, more than 95%, more than 90%, more than 75%) of the total aerodynamic force generated by the aerial device (possibly excluding a drag force generated by the body such as during flight at high airspeeds) . Alternatively or additionally, the aerial device includes any other suitable flight components that function to generate forces for aerial system flight, such as jet engines, rocket engines, wings, solar sails, and/or any other suitable force-generating components.

In various embodiments, the aerial device has 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 rotors, placed as determined by one of skill in the art. The rotors may be substantially evenly dispersed about the aerial system body, and each rotor plane may be substantially parallel (e.g., within 10 degrees) to a lateral plane of the aerial system body (e.g., encompassing the longitudinal and lateral axes) . The rotors typically occupy a relatively large portion of the entire aerial device (e.g., 90%, 80%, 75%, or majority of the aerial system footprint, or any other suitable proportion of the aerial device) . For example, the sum of the square of the diameter of each rotor can be greater than a threshold amount (e.g., 10%, 50%, 75%, 90%, 110%, etc. ) of the convex hull of the projection of the aerial device onto a primary plane of the system (e.g., the lateral plane) . However, the rotors can be otherwise arranged.

The aerial device may further include sensors for recording signals indicative of aerial system operation, the ambient environment surrounding the aerial device (e.g., the physical space proximal the aerial device) , and/or other parameters. The sensors are typically mounted to the body, powered by the power supply, and controlled by the processing system. Non-limiting examples of sensors include additional cameras (e.g., CCD, CMOS, multispectral, visual range, hyperspectral, stereoscopic, etc. ) , orientation sensors (e.g., inertial measurement sensors, accelerometer, gyroscope, altimeter, magnetometer, etc. ) , audio sensors (e.g., transducer, microphone, etc. ) , barometers, light sensors, temperature sensors, current sensor (e.g., Hall effect sensor) , air flow meter, voltmeters, touch sensors (e.g., resistive, capacitive, etc. ) , proximity sensors, force sensors (e.g., strain gauge meter, load cell) , vibration sensors, chemical sensors, sonar sensors, location sensor (e.g., GPS, GNSS, triangulation, etc. ) , and/or the like.

The aerial device also includes a power supply which provides power to the active components of the aerial device. The power supply may be mounted to the body and electrically connected to all of the active components of the aerial device (e.g., directly or indirectly) . The power supply may be a primary battery, secondary battery (e.g., rechargeable battery) , fuel cell, energy harvester (e.g., solar, wind, etc. ) , or be any other suitable power supply. Non-limiting examples of secondary batteries include batteries including lithium chemistry (e.g., lithium ion, lithium ion polymer, etc. ) , nickel chemistry (e.g., NiCad, NiMH, etc. ) , or batteries with any other suitable chemistry.

Two-Axis Gimbal System 10

Referring back now to the system 10, itself, the system 10 includes a camera module 12. The camera module 12 typically includes a camera board 64, camera electronics, connector devices, and fixing frames 62, each of which can be selected by one of skill in the art. The camera module 12 may include one or more individual cameras 72. The cameras 72 may include a single lens camera (e.g., CCD camera, CMOS camera, etc. ) , a stereo-camera, a hyperspectral camera, a multispectral camera, or any other suitable imaging or optical sensor. The camera module 12 may define one or more active surfaces that receive light, but can alternatively include any other suitable component. For example, an active surface of a camera 72 can be an active surface of a camera sensor (e.g., CCD sensor, CMOS sensor, etc. ) , typically including a regular array of sensor pixels. The camera sensor or other active surface may be substantially planar and rectangular (e.g., having a first sensor edge, a second sensor edge opposing the first sensor edge, and third and fourth sensor edges each perpendicular to and extending from the first sensor edge to the second sensor edge) . Alternatively, the camera sensor can have any suitable shape and/or topography. The camera 72 can produce an image frame, which typically corresponds with the shape of the active surface (e.g., rectangular, having a first and second frame edge opposing each other, etc. ) . The image frame also defines a regular array of pixel locations, with each pixel location corresponding to a sensor pixel of the active surface and/or pixels of the images sampled by the camera 72. Alternatively, the image frame can have any suitable shape. The image frame may also define aspects of the images sampled by the camera 72 (e.g., image dimensions, resolution, pixel size and/or shape, etc. ) . In addition, the camera 72 may include a zoom lens, digital zoom, fisheye lens, filter, or any other suitable active or passive optical adjustment. Application of the optical adjustment can be actively controlled by the remote device, by another controller, or manually by an operator (e.g., where the operator manually sets the adjustment) . In an embodiment, the camera module 12 includes a housing 74 enclosing at least some of the optical system components.

The system 10 also includes a pitch axis motor assembly 14 including a stator part 16 and a rotary part 18 wherein the stator part 16 is coupled to the camera module 12 along a pitch axis P. The pitch axis motor assembly 14 drives the camera module 12 to pivot around the pitch axis P. The pitch axis motor assembly 14 includes electrical devices and connections as chosen by one of skill in the art.

The system 10 also includes a roll axis motor assembly 20 including a second stator part 22 and a second rotary part 24. The roll axis motor assembly 20 includes electrical devices and connections as chosen by one of skill in the art. One or both of these motor assemblies 14, 20 can be any suitable pitch axis motor assembly 14 or roll axis motor assembly 20 known in the art, respectively. For example, one or both motor assemblies 14, 20 may be or include an electric motor or any other suitable motor. Non-limiting examples of electric motors that can be used include DC motors (e.g., brushed motors) , EC motors (e.g., brushless motors) , induction motor, synchronous motor, magnetic motor, or any other suitable electric motor.

The system 10 further includes a first bracket 26 having two ends (e.g. a first end and a second end) 46, 48 wherein one end 46 of the first bracket 26 is coupled to the stator part 16 of the pitch axis motor assembly 14 along a roll axis R and the other end 48 is coupled to the second rotary part 24 of the roll axis motor assembly 20 such that the first bracket 26 is driven directly by the roll axis motor assembly 20 to pivot around the roll axis R. The system 10 further includes a second bracket 28 having two ends (e.g. a first end and a second end) 50, 52 wherein one end 50 is coupled to the second stator part 22 of the roll axis motor assembly 20.

The system 10 also includes a control board assembly 30 including a main control board and connector devices. The main control includes a processor for executing computer-readable instructions, wherein the control board assembly 30 is coupled to the camera module 12, the pitch axis motor assembly 14, and the roll axis motor assembly 20 for data transmission, control signal transmission, and power supply. The control board assembly 30 includes one or more processors configured to execute one or more software programs for controlling the operation of the system 10 and/or the aerial device. In an example, the control board assembly 30 may receive operation instructions (such as from various components) , interpret the operation instructions into machine instructions, and control the system 10 based on the machine instructions (individually or as a set) . The control board assembly 30 may additionally or alternatively process images recorded by the camera module 12, stream images to a remote device (e.g., in real-or near-real time) , and/or perform any other suitable functionality. The processor (s) of the control board assembly 30 may be a CPU, GPU, and/or the like. In addition, the control board assembly 30 may include a memory (such as a Flash memory, RAM, etc. ) , or any other suitable processing component. In an embodiment, the control board assembly 30 may also include dedicated hardware that automatically processes images obtained from the camera module 12 (e.g., de-warps the image, filters the image, crops the image, etc. ) prior to transmission.

The system 10 further includes a cable connection assembly 32. The cable connection assembly 32 can include a transmission cable assembly of the camera module 40, a connection cable assembly of the pitch axis motor 42, and a connection cable assembly of the roll axis motor 44. The system 10 may also include a cable guiding/concealing cover 34 which may cover all or a portion of any one or more components of the system 10.

The transmission cable assembly of the camera module 40 includes electrical connector devices 54 at both ends and an intermediate flexible cable 58, wherein the electrical connector device 54 at one end is connected with the camera module 12 and the other end is connected with a connector device of control assembly 56. The intermediate flexible cable 58 is typically a coaxial cable which is drawn from an end of the camera module 12 that is not connected with the pitch motor assembly 14. Then the intermediate flexible cable 58 is typically bent and passed through a channel 76 reserved on the first bracket 26, and then is typically bent again turning to the back of the second bracket 28, and then typically extends upward to the control assembly 30.

The connection cable assembly of the pitch axis motor 42 includes electrical connector devices at both ends and a second intermediate flexible cable, wherein the electrical connector device at one end is connected with an electrical connector device of the pitch axis motor 36 and the other is connected with a connector device of control assembly 56. The second intermediate flexible cable is typically a coaxial cable, which shares one channel with the flexible cable of the transmission cable assembly of camera module 40. First, the second intermediate flexible cable typically enters the inside of the frame 62/camera module 12 from one end and then emerges from the other end. Then the second intermediate flexible cable is typically bent, passing through the channel reserved on the first bracket 26. Then the second intermediate flexible cable is typically bent again turning to the back of the second bracket 28 and typically extends upward to the control assembly 30.

The connection cable assembly of the roll axis motor 44 includes electrical connector devices at both ends and a third intermediate flexible cable 80, wherein the electrical connector device at one end is connected with an electrical connector device of the roll axis motor 38 and the other is connected with the connector device of control assembly 56. The third intermediate flexible cable 80 passes through a channel reserved on the second bracket 28 and extends upward to the control assembly 30.

In other embodiments, such as the embodiment set forth in Figure 2, by adjusting the weight and position of one or more counterweights 60 on the first bracket 26, or by directly adjusting the arrangement of the components without any additional counterweight, the load center of gravity of the camera module 12 can be shifted away from the roll axis R. By adjusting the distance of center of gravity of the load portion to the roll axis R, the torque generated by the center of gravity relative to the roll axis R can counteract the torque generated by the bending of the transmission cable assembly of the camera module 40 and the connection cable assembly of the pitch axis motor assembly 42. As a result, the power consumption of the roll axis motor assembly 20 can be reduced as the camera angle is at or near a normal or default position.

System Assembly Procedure

This disclosure also provides a system 10 assembly procedure. In various embodiments, the pitch axis motor assembly 14 is mounted on the side of the camera module 12. A coaxial cable connecting the pitch axis motor assembly 14 is inside the camera module 12, and emerges through an orifice on the side of the camera module 12, e.g., as shown in Figure 4. A camera board 64 can be affixed by any suitable adhesive. In another embodiment, the camera coaxial cable emerges through the orifice on the side as well, e.g., as shown in Figure 5. In still another embodiment, the roll axis motor assembly 20 is fixed on a roll arm 66 and the counterweight 60 is fixed on the side of the roll arm 66. A roll arm 66 can be vertically mounted with the camera module 12 from the side, e.g., as shown in Figures 6A and 6B. Further, as is shown in Figures 6C and 6D the camera module 12 may be rotated 90 degrees followed by fitting of a rear cover and fastening of screws. Moreover, as shown in Figures 6E and 6F, a roll arm cover 82 may then be mounted with buckles and screws at both ends to prevent deformation. Subsequently, after a flexible printed circuit 68 is connected, a yaw arm assembly 70 can be mounted. Then screws can be fastened and the flexible printed circuit 68 can be folded and fixed on the back of the yaw arm assembly 70 by double-sided tape, e.g., as shown in Figures 7A and 7B. In various embodiments, a shifted center of mass/gravity counteracts the residual torque generated by the bending cables. Such design concepts can be further extended to any single axis/multiple axes gimbal systems.

The invention has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. It is now apparent to those skilled in the art that many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that the invention may be practiced otherwise than as specifically described.

Claims

A two-axis gimbal system comprising:

a camera module;

a pitch axis motor assembly comprising a stator part and a rotary part wherein said stator part is coupled to said camera module along a pitch axis and wherein said pitch axis motor assembly drives said camera module to pivot around the pitch axis;

a roll axis motor assembly comprising a second stator part and a second rotary part;

a first bracket having two ends wherein a first end is coupled to said stator part of said pitch axis motor assembly along a roll axis and a second end is coupled to said second rotary part of said roll axis motor assembly such that said first bracket is driven by said roll axis motor assembly to pivot around the roll axis;

a second bracket having a first end coupled to said second stator part of said roll axis motor; and

a control board assembly including a processor for executing computer-readable instructions, wherein said control board assembly is coupled to said camera module, said pitch axis motor assembly, and said roll axis motor assembly for data transmission, control signal transmission, and power supply.