Arm-equipped unmanned aerial vehicle and control method therefor

Abstract

An arm-equipped unmanned aerial vehicle and a control method therefor, the arm-equipped unmanned aerial vehicle comprising a tilting quadrotor unmanned aerial vehicle, a mechanical arm, and a control module (7). The tilting quadrotor unmanned aerial vehicle comprises a fuselage, tilting driving devices and tilting arms, the mechanical arm being mounted below the fuselage, the control module (7) being mounted above the fuselage, and the tilting driving devices being respectively arranged on two sides of the fuselage. Each tilting driving device is in drive connection to a tilting arm, the tilting arms extending from the head of the fuselage to the rear of the fuselage, and the tilting driving devices being used for driving the tilting arms to rotate in a vertical plane. The two ends of each tilting arm are each provided with a rotor mechanism that can be driven to rotate. The mechanical arm, the tilting driving devices and the rotor mechanisms are all connected and driven by the control module (7).

Description

A drone with arms and control method thereof Technical Field

[0001] The present invention relates to the technical field of flying robots, and in particular to an arm-mounted drone and a control method thereof. Background Art

[0002] With the rapid development and widespread adoption of drone technology, drones are increasingly being used in production and daily life, for example, in high-altitude harvesting, aerial transportation, power system maintenance, and high-altitude cleaning. Drone technology has brought convenience to many high-altitude work scenarios, improved safety, and reduced operating costs, resulting in significant economic benefits. Consequently, a number of flying robots incorporating drone technology have emerged. Among these flying robots, drones with arms are a particularly popular type. By combining drones with robotic arms, they combine the flexibility and maneuverability of drones with the interactive capabilities of robotic arms, significantly expanding their application scenarios. The maneuverability and interactivity of drones with arms enable them to replace humans in delicate operations in dangerous or challenging situations, presenting them with enormous potential for development.

[0003] Most current drones with arms are based on multi-rotor drones. However, traditional multi-rotor drones only have four controllable degrees of freedom. This underactuation leads to coupling between the drone's position control and attitude control, posing challenges to the drone's positioning and operational accuracy. This also increases the difficulty of control system design, significantly impacting the drone's reliability and safety during high-altitude operations. Although some drones with arms currently exist based on fully-driven multi-rotor drones, their complex control technology and low reliability make them difficult to implement in practice.

[0004] Summary of the Invention

[0005] In response to the problems existing in the prior art, one of the objectives of the present invention is to provide a drone with arms that can increase independent control of the drone's pitch movement and achieve higher-precision tracking and positioning.

[0006] A second object of the present invention is to provide a control method for an unmanned aerial vehicle with arms.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] An arm-equipped drone, comprising a tilt-rotating quad-rotor drone, a robotic arm, and a control module;

[0009] The tilt-quadrotor drone is equipped with a vision module and a positioning module for target detection and positioning, and a tilt drive device is installed on both sides of the fuselage;

[0010] Each tilt drive device is connected to a tilt arm, which extends horizontally from the front of the fuselage to the rear of the fuselage. The tilt drive device is used to drive the tilt arm to rotate in a vertical plane.

[0011] Each tilt arm is provided with a rotor mechanism at both ends;

[0012] The tilting drive device is connected to the control module, and the control module is used to control the action of the tilting drive device;

[0013] The robotic arm is installed directly below the tilt-rotating quadrotor drone, and the end of the robotic arm is suitable for installing different types of end effectors.

[0014] Furthermore, the tilt drive device includes a steering gear and a steering wheel. The steering gear is fixed to the fuselage, and the steering gear and the tilt arm are connected through the steering wheel.

[0015] Furthermore, the tilt arm includes a tilt arm fixing part, a tilt arm cross bar and a support shaft. The support shaft is horizontally hinged to the fuselage. The tilt arm fixing part is fixed to the steering wheel and sleeved on the support shaft. The middle part of the tilt arm cross bar is fixed to the tilt arm fixing part. The rotor mechanism includes a motor and blades. Motors are respectively installed at both ends of the tilt arm cross bar, and the motor drive is connected to the blades.

[0016] Furthermore, the fuselage is fixedly connected to a tilting base, the tilting base is provided with two upward protrusions at intervals, the support shaft is horizontally passed through the two protrusions, and the tilting arm is embedded between the two protrusions.

[0017] Furthermore, the fuselage includes a crossbeam extending from the left side of the fuselage to the right side of the fuselage. The crossbeam is perpendicular to the tilt arm cross bars on both sides. The tilt base and the steering gear are respectively fixed to the crossbeam.

[0018] Furthermore, the robotic arm is equipped with a built-in control core board for identifying the connected end effector device ID and communicating with the control module to adjust the control mode of the end effector to achieve compatibility with different end effectors.

[0019] A control method for an arm-mounted drone comprises the following steps:

[0020] The tilting arm is driven to rotate in a vertical plane by a tilting drive device, so that the tilting arm and the rotor mechanisms arranged at both ends of the tilting arm are tilted;

[0021] Lift is generated by driving the rotor mechanism, and the direction of the lift changes as the tilt arm tilts, increasing independent control over the pitch movement of the drone.

[0022] Furthermore, the motor lift and torque required for the drone to reach the target position are calculated;

[0023] The calculated motor lift and torque are converted into the required servo tilt angle and motor speed using the control allocation scheme;

[0024] According to the conversion results, the steering angle of the servo and the speed of the motor are adjusted accordingly.

[0025] Furthermore, the allocation scheme includes obtaining the mapping relationship between the servo angle and the motor speed to generate the motor lift and torque through force analysis, and converting the problem of solving the mapping relationship between the motor lift and torque and the servo angle and the motor speed into a quadratic programming problem through substitution;

[0026] The Lagrange multiplier method is used to solve the quadratic programming problem and obtain a set of optimal solutions, thereby obtaining the mapping relationship between the motor lift and torque to the servo angle and motor speed.

[0027] Furthermore, the overall control process includes the following steps:

[0028] Automatically identify the type of end effector installed at the end of the robotic arm and match the control mode;

[0029] In flight mode, the robotic arm retracts directly below the drone and remains relatively stationary. Based on the information of the given target operation point, the positioning module and control module control the drone to fly near the target operation point.

[0030] The positioning module and the vision module determine that the drone has reached a suitable position for operation and switches to the operation mode. The control module controls the drone to maintain a stable attitude and position.

[0031] The visual module identifies the work target and the control module controls the end of the robotic arm to approach the work point to perform the work;

[0032] After confirming that the current task is completed, switch to flight mode and fly to the next target operation point;

[0033] Repeat the above steps until all tasks are completed and return.

[0034] In general, the present invention has the following advantages:

[0035] 1. The tilt-quadrotor drone of this invention builds upon traditional quadrotor drones by installing tilt drive mechanisms on both sides of the fuselage. This allows the tilt arms to rotate in the vertical plane, changing the direction of lift generated by the rotor mechanism. This provides independent control over the drone's pitch motion, enabling higher-precision tracking and positioning. Compared to existing fully-driven multi-rotor drones, the drone of this invention has fewer actuator mechanisms, facilitating the practical application of arm-mounted drones.

[0036] 2. The arm-mounted drone designed by the present invention constructs an aerial interactive platform. By designing a unified interface at the end of the robotic arm, it achieves compatibility and automatic recognition of different types of end effectors, enabling the arm-mounted drone to handle different types of work tasks, thereby improving its scope of application and expanding its application space. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic structural diagram of an embodiment of the present invention.

[0038] FIG2 is a connection diagram of the tilting mechanism.

[0039] FIG3 is a schematic structural diagram of the tilting base.

[0040] FIG4 is a schematic structural diagram of the tilt arm.

[0041] FIG5 is a flow chart of a control algorithm of a tilt-quadrotor UAV according to an embodiment of the present invention.

[0042] FIG6 is a schematic structural diagram of the second joint end of the robotic arm.

[0043] FIG7 is a flowchart of high-altitude operations of a drone with arms according to an embodiment of the present invention.

[0044] In the figure: 1-propeller blade; 2-motor; 3-crossbeam; 4-servo; 5-servo bracket; 6-positioning module; 7-control module; 8-motor base; 9-tilt arm crossbar; 10-first tilt arm fixing part; 11-second tilt arm fixing part; 12-power distribution board; 13-battery compartment; 14-robotic arm base; 15-first joint of the robotic arm; 16-second joint of the robotic arm; 17-end effector; 18-battery; 19-vision module; 20-support shaft; 21-tilt base; 22-first bearing; 23-second bearing; 24-steering wheel; 25-motor base fixing part; 26-motor base platform; 27-cross base. DETAILED DESCRIPTION

[0045] The present invention will be described in further detail below.

[0046] As shown in Figure 1, an arm-mounted drone includes a special "H"-shaped structure consisting of a beam 3 main body and two tilting mechanisms, specifically including a fuselage, a tilting arm, a robotic arm, a replaceable end effector 17, a vision module 19, a positioning module 6 and a control module 7.

[0047] The main body of the crossbeam 3 features a battery compartment 13 for housing the battery 18. Mounting platforms are located on both the upper and lower sides of the battery compartment 13, allowing modules such as the positioning module 6, control module 7, power distribution board 12, robotic arm base 14, and vision module 19 to be placed and connected in their pre-set locations. Fixing holes are designed on both sides of the crossbeam 3 for mounting and connecting the tilt mechanism.

[0048] The visual module 19 is located on the outside of the lower part of the drone and is used for identifying and locating targets;

[0049] The positioning module 6 is located above the drone body and includes various sensors such as GPS and barometer for spatial positioning of the drone;

[0050] The control module 7 is the control core of the UAV, which is used to control the position and posture of the UAV, the motion trajectory of the robotic arm and the action of the end effector 17, as well as the data processing of the positioning module 6 and the vision module 19;

[0051] The tilt mechanism includes a steering gear 4 , a steering gear bracket 5 , a tilt base 21 , a tilt arm, and a support shaft 20 . The tilt arm can rotate around the support shaft 20 .

[0052] The specific connection method of the tilt mechanism is shown in Figure 2. The steering gear 4 is fixed to a suitable position on the side of the crossbeam 3 via the steering gear bracket 5. The tilt base 21 is also fixed to a suitable position on the side of the crossbeam 3 via the fixing holes. The tilt arm is connected to the tilt base 21 via the support shaft 20, allowing the tilt arm to tilt around the support shaft 20. The tilt arm is connected to the steering gear 4 via the steering wheel 24.

[0053] To reduce friction during tilt arm rotation and improve tilting accuracy and service life, a dual-bearing structure is designed on tilt base 21. As shown in Figure 3, tilt base 21 features two raised inverted U-shaped columns with coaxial through-holes for mounting support shaft 20. Furthermore, the two inverted U-shaped columns have two bearing mounting holes for mounting a first bearing 22 and a second bearing 23. Support shaft 20 passes through these through-holes.

[0054] In addition, the tilt arm is an integral structure, and its specific structure is shown in FIG4 , including: a tilt arm cross bar 9, a tilt arm fixing member, a motor base platform 26, a motor base fixing member 25, and a cross base 27;

[0055] The tilt arm fixtures consist of a first tilt arm fixture 10 and a second tilt arm fixture 11, arranged in a vertical arrangement. The tilt arm crossbar 9 is secured to the first and second tilt arm fixtures 10, 11 via screws and nuts. The side of the second tilt arm fixture 11 has four mounting holes for the steering wheel 24 and a through-hole for the support shaft 20.

[0056] Motor bases 8 are symmetrically mounted on either side of the tilt arm crossbar 9. These motor bases 8 comprise a motor base platform 26, a motor base fixture 25, and a cross base 27. The motor base platform 26 is secured to the tilt arm crossbar 9 via fixing holes and reinforced by the motor base fixture 25. The cross base 27 is secured to the motor base platform 26 via fixing holes and is used to mount and secure the motor 2. Motor 2 is equipped with blades 1, which generate lift when driven by the motor 2. When the tilt arm tilts, the blades 1 at each end of the tilt arm can rotate accordingly, changing the direction of the lift.

[0057] The above-mentioned tilt mechanism withstands the longitudinal force generated by the tilt arm and the blade 1 through the support shaft 20 and the tilt base 21, and the servo 4 only needs to provide the torque required for tilting, which can reduce the workload of the servo 4 and thus improve the service life and control accuracy of the tilt mechanism.

[0058] Since the quadcopter drone of this embodiment is a new type of structure, its control algorithm needs to be specifically designed. The specific control algorithm process for the drone's position and attitude control is shown in Figure 5: First, the desired position and attitude information as well as the drone's current actual position and attitude information are input; then the position controller, position and attitude decoupler, and attitude controller are used to calculate the force and torque required to reach the desired position and attitude; finally, the required force and torque are converted into the servo 4 angle and motor 2 speed that the drone can provide through the designed control allocation algorithm and output. Here, the design of the position controller and attitude controller can adopt the traditional PID algorithm (existing technology). The key to the control algorithm design lies in the design of the control allocation scheme.

[0059] The specific steps of controlling the allocation plan are as follows:

[0060] Since there is a mapping relationship between the lift f of motor 2 and the speed ω: f=C T ω 2 ;

[0061] Among them C T is the tension coefficient of motor 2, which is a known constant.

[0062] For convenience, we first consider the relationship between force and torque and the steering gear 4 rotation angle and motor 2 lift. Through the mechanism of force and torque generation, we obtain the mapping relationship between the steering gear 4 rotation angle and motor 2 lift force and torque (1):

[0063] Among them F x ,F y ,F z ,τ x ,τ y ,τz is the generated force and torque, f l1 ,f l2 ,f r1 ,f r2 ,α l ,α r The lift provided by the four motors 2 and the tilt angle of the two tilt servos 4, l, h, d, k are known constants, c(·) represents cos(·), and s(·) represents sin(·).

[0064] Let f lx =(f l1 +f l2 )sin(a l );f lz =(f l1 +f l2 )cos(a l ); f rx =(f r1 +f r2 )sin(a r );f lz =(f r1 +f r2 )cos(a r ); f=[f lx ,f rx ,f lz ,f rz ] T ; F=[F x ,F z ,τ x ,τ z ] T ;

[0065] Thus, we can get a four-to-four linear mapping relationship:

[0066] A is a reversible matrix, so the value of f can be solved by F, f = A -1 F.

[0067] Further, by α l =arctan(f lx / f lx ); α r =arctan(f rx / f rz );

[0068] We can solve for f l1 +f l2 ,f r1 +f r2 ,α l ,αr The value of f can be obtained by combining the mapping relationship (1) with three equations. l1 ,f l2 ,f r1 ,f r2 This is a multi-solution problem and some constraints need to be added to determine a set of feasible solutions.

[0069] Given the following objective function J = (f l1 -f l2 ) 2 +(f r1 -f r2 ) 2 ;

[0070] The control allocation problem is converted into a quadratic programming problem, and then the Lagrange multiplier method (existing technology) is used to solve the optimal solution to obtain the required tilt angle and motor 2 lift, which are finally further converted into the required steering gear 4 angle and motor 2 speed.

[0071] Under the premise of ensuring that the output can generate the force and torque required by the drone, the above objective function has the following advantages: on the one hand, it ensures that the overall speed of the four motors 2 is relatively low, which can reduce the possibility of the speed of a motor 2 being too high or too low, and ensure that the speed of the motor 2 is within the feasible range as much as possible, thereby improving the service life of the motor 2 to a certain extent; on the other hand, it ensures that the speed difference of the motors 2 on the same side is small, so that the lift difference generated by the two motors 2 on the same side is also small, thereby reducing the torque on the tilt arm and reducing the burden on the tilt mechanism.

[0072] As shown in Figure 1, the arm-mounted drone of this embodiment is equipped with a two-link robotic arm consisting of a first joint 15 and a second joint 16, capable of moving within the plane of the drone's pitch angle. The robotic arm base 14 is fixed to the center of the platform below the drone, and the robotic arm moves only in a plane perpendicular to the drone's crossbar 3. The end of the robotic arm can be used to mount an end effector 17. Details of the end of the second joint 16 are shown in Figure 6. A control core board is housed within the second joint 16, while a mounting interface and a signal transmission interface for the end effector 17 are located on the outer side of the end of the second joint 16. The end effector 17 is secured to the end of the robotic arm via the mounting interface, while signal transmission and control are achieved via the signal transmission interface. The built-in control core board automatically identifies the device ID of the connected end effector 17 and communicates with the control module 7 to adjust the control mode of the end effector 17, ensuring compatibility with different end effectors 17.

[0073] The replaceable end effector 17 includes various types such as grippers, magnetic heads, nozzles, and shearing mechanisms, which can be used for various operations such as clamping, magnetic suction, cleaning, and shearing. Each end effector 17 uses a universal mounting interface and signal transmission interface, and is provided with a different identifiable device ID number.

[0074] In this embodiment, the drone part of the arm-mounted drone has five independently controllable degrees of freedom, which can realize independent control of the drone's position, yaw angle and pitch angle; compared with the traditional four-rotor drone, independent control of the drone's pitch angle is added, and combined with the two-link robotic arm inverted under the drone, a movable flight interactive platform is formed, which has higher maneuverability and adaptability, can achieve higher-precision position and attitude control, and can perform more precise operations. By carrying different end effectors 17 at the end of the robotic arm, various high-altitude operation needs such as high-altitude grasping, transportation, cleaning, and picking can be realized.

[0075] In this embodiment, the drone with arms has two working modes: flight mode and operation mode. The switching between the two is determined by the positioning module 6 and the visual module 19 to detect whether the target operation point has been reached.

[0076] As shown in Figure 7, in flight mode, the robotic arm retracts directly below the drone and remains relatively stationary. The controller controls the drone's posture and position and moves it to the vicinity of the target operation point.

[0077] When the positioning module 6 and the visual module 19 determine that the target operation point has been reached, the operation mode is switched;

[0078] When in operation mode, the controller starts to control the robotic arm. At this time, the drone serves as the mobile base of the robotic arm, keeping its posture as stable as possible so that the trajectory control of the end of the robotic arm can achieve a higher accuracy. Different types of end effectors 17 can be selected to be loaded at the end of the robotic arm according to different operation types.

[0079] Based on the above embodiment, the present invention also provides a control method for an arm-mounted drone, comprising the following steps:

[0080] Step 1: Select the appropriate end effector 17 according to the required task and install it at the end of the robotic arm. The robotic arm automatically identifies the type of end effector 17 and matches the control mode.

[0081] Step 2: The UAV with arms enters flight mode. Given the information of the target operation point, the positioning module 6 and the control module 7 use the designed control algorithm to control the UAV to fly near the target operation point.

[0082] Step 3: The positioning module 6 and the visual module 19 determine that the position suitable for the operation has been reached and switch to the operation mode;

[0083] Step 4: Identify the work target through the visual module 19, and control the end of the manipulator arm to approach the work point through the control module 7, while ensuring the stability of the UAV's posture and the stability of the manipulator arm base 14 to carry out the current work task;

[0084] Step 5: After confirming the completion of the current task, the drone switches to flight mode and flies to the next target operation point;

[0085] Step 6: Repeat steps 1 to 5 until all tasks are completed and returned.

[0086] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An arm-equipped drone, characterized in that: It includes a tilt-rotor quadcopter, a robotic arm, and a control module; The fuselage of the tilt-rotor quadcopter is equipped with a vision module and a positioning module for target detection and positioning. Tilt drive devices are respectively arranged on both sides of the fuselage; Each tilt drive device is drivingly connected to a tilt arm. The tilt arm extends horizontally from the front of the fuselage to the rear of the fuselage. The tilt drive device is used to drive the tilt arm to rotate in the vertical plane; Rotary wing mechanisms are respectively arranged at both ends of each tilt arm; The tilt drive device is connected to the control module, and the control module is used to control the actions of the tilt drive device; The robotic arm is installed directly below the tilt-rotor quadcopter, and different types of end effectors are adaptively installed at the end of the robotic arm.

2. The arm - equipped drone according to claim 1, wherein: The tilt drive device includes a servo motor and a steering wheel. The servo motor is fixedly connected to the fuselage, and the servo motor and the tilt arm are connected through the steering wheel.

3. The arm - equipped drone according to claim 2, wherein: The tilt arm includes a tilt arm fixing member, a tilt arm cross bar, and a support shaft. The support shaft is horizontally hinged to the fuselage. The tilt arm fixing member is fixedly connected to the steering wheel and sleeved on the support shaft. The middle of the tilt arm cross bar is fixedly connected to the tilt arm fixing member. The rotary wing mechanism includes a motor and a propeller. Motors are respectively installed at both ends of the tilt arm cross bar, and the motors are drivingly connected to the propellers.

4. The arm - equipped drone according to claim 3, characterized in that: The fuselage is fixedly connected with a tilt base. Two upward protrusions are arranged at intervals on the tilt base. The support shaft horizontally penetrates through the two protrusions, and the tilt arm is embedded between the two protrusions.

5. The arm - equipped drone according to claim 4, wherein: The fuselage includes a cross beam that extends from the left side of the fuselage to the right side of the fuselage. The cross beam is perpendicular to the tilt arm cross bars on both sides. The tilt base and the servo motor are respectively fixedly connected to the cross beam.

6. The quadrotor UAV according to claim 1, characterized in that: The robotic arm is internally provided with a control core board, which is used to identify the ID of the connected end effector device and communicate with the control module to adjust the control mode of the end effector, so as to achieve the compatibility of different end effectors.

7. A control method for an arm-equipped unmanned aerial vehicle according to any one of claims 1-6, characterized in that: It includes the following steps, Drive the tilt arm to rotate in the vertical plane through the tilt drive device, so that the tilt arm and the rotary wing mechanisms arranged at both ends of the tilt arm are tilted; Generate lift by driving the rotary wing mechanism. The direction of the lift changes with the tilt of the tilt arm, increasing the independent control of the pitch movement of the drone.

8. A control method for an arm-equipped drone according to claim 7, characterized in that: Calculate the motor lift and torque required for the drone to reach the target position; Using a control allocation scheme, convert the calculated motor lift and torque into the required servo motor tilt angle and motor speed; Adjust the rotation angle of the servo motor and the rotation speed of the motor according to the conversion results.

9. A control method for an arm-equipped unmanned aerial vehicle according to claim 8, characterized in that: The allocation scheme includes obtaining the mapping relationship between the servo motor tilt angle and motor speed to generate motor lift and torque through force analysis. Through substitution, the problem of solving the mapping relationship between motor lift and torque to servo motor tilt angle and motor speed is converted into a quadratic programming problem; Use the Lagrange multiplier method to solve the quadratic programming problem to obtain a set of optimal solutions, so as to obtain the mapping relationship between motor lift and torque to servo motor tilt angle and motor speed.

10. A control method for an arm-equipped unmanned aerial vehicle according to claim 8, characterized in that: Overall control process It includes the following steps, Automatically identify the type of the end effector installed at the end of the robotic arm and match the control mode; Enter the flight mode. The robotic arm retracts directly below the drone and remains relatively stationary. According to the information of the given target operation point, control the drone to fly near the target operation point through the positioning module and the control module; Determine the position suitable for operation through the positioning module and the vision module, switch to the operation mode, and the control module controls the UAV to maintain stable attitude and position; Identify the operation target through the vision module, and control the end of the robotic arm to approach the operation point for operation through the control module; After confirming the completion of the current operation task, switch to the flight mode and fly to the next target operation point; Repeat the above steps until all operation tasks are completed and return.

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