Shipborne mechanical arm grabbing docking force control method for assisting landing of unmanned aerial vehicle

Abstract

The invention discloses a ship-borne mechanical arm grabbing butt joint force control method for assisting landing of an unmanned aerial vehicle, the position of a mechanical arm tail end executor is controlled through an established ship-borne mechanical arm dynamic model and an established ship motion model, and the ship-borne mechanical arm dynamic model receives a track of a tracking instruction. Comprising the steps that according to the position of an end effector of the mechanical arm, a track of a tracking instruction and a preset reference track, the position deviation between the track of the tracking instruction and the reference track is obtained; according to the position of the mechanical arm tail end executor and the position of the unmanned aerial vehicle to be landed, the actual contact pressure of the butt joint contact face is obtained; obtaining a force deviation according to the actual contact pressure and a preset expected tracking force; and obtaining an impedance control model according to the position deviation and the force deviation, and calculating a dynamic force tracking error by using the impedance control model to obtain a stable force tracking result.

Description

Technical Field

[0001] The present invention relates to the technical field of docking force control, and in particular to a method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a drone. Background Art

[0002] Unmanned ship-borne drones have begun to play an increasingly important role in many fields, such as over-the-horizon detection and air early warning in the development of marine resources. The recovery of traditional boat-borne drones follows or improves the fixed-point return method of land-based drones, unilaterally improving the adaptive all-terrain landing capability of drones, decoupling the recovery motion in terms of navigation accuracy and flight attitude control, and generating the optimal deck landing trajectory of drones through technologies such as equiangular glide path rate control, approach power compensation, and direct force control, and is mainly used in ideal water surface environments such as static water surface and uniform linear motion of the boat body.

[0003] However, in the "last meter" spatial scale of the landing process, the fixed-point return "carving a boat to find a sword" and the deck disturbance problem make the UAV landing in a dynamic environment dangerous and the accident rate high. Therefore, studying a reliable landing aid method is a necessary means to ensure the safe recovery of the UAV on board. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV, which can directly output the joint torque of the mechanical arm and estimate the disturbance force, thereby helping to improve the safety of autonomous recovery and landing of the UAV.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] The present invention provides a method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV, wherein the position of the end effector of the mechanical arm is controlled by using an established ship-borne mechanical arm dynamic model and a ship motion model, and the ship-borne mechanical arm dynamic model receives the track of the tracking instruction, and the method comprises:

[0007] Obtaining a position deviation between the track of the tracking instruction and the reference track according to the position of the end effector of the robot arm, the track of the tracking instruction and a preset reference track;

[0008] According to the position of the end effector of the robot arm and the position of the drone to be landed, an actual contact pressure of the docking contact surface is obtained; according to the actual contact pressure and a preset expected tracking force, a force deviation is obtained;

[0009] An impedance control model is obtained according to the position deviation and the force deviation, a dynamic force tracking error is calculated using the impedance control model, and a stable force tracking result is obtained according to the dynamic force tracking error.

[0010] Optionally, when the stiffness of the docking contact surface between the end effector of the manipulator and the drone to be landed cannot be obtained, the position of the docking contact surface is used as a reference track to obtain a new impedance control model;

[0011] Calculating a new stable force tracking result according to the new impedance control model;

[0012] According to the new stable force tracking result, an adaptive variable impedance contact force controller is obtained, which is used to adaptively adjust the stiffness of the butt contact surface.

[0013] Optionally, the dynamic model of the robotic arm is expressed as:

[0014] ;

[0015] In the formula, represents the inertial mass of the end effector of the robot arm; The vector representing the angular acceleration of the generalized joints of the robot; The vector representing the angular velocity of the generalized joints of the robot; represents the Coriolis force matrix of the robot arm; represents the gravitational torque of the robot arm; represents the inertia matrix of the ship; Represents the acceleration vector of the ship in the hull coordinate system; Represents the velocity vector of the ship in the hull coordinate system; represents the Coriolis force of the ship; Represents the driving torque of the robot joint; represents the disturbance caused by the friction of the robot joint; Represents the workspace position of the robot end effector in the inertial coordinate system; represents the Jacob matrix of the ship; Represents the Jacob matrix of the robotic arm.

[0016] Optionally, the ship motion model is expressed as:

[0017] ;

[0018] In the formula, Indicates the rate of change of ship position; represents the rotation matrix of the ship; Represents the acceleration vector of the ship in the hull coordinate system; Represents the velocity vector of the ship in the hull coordinate system; represents the nominal part of the inertia matrix of the ship motion model; represents the nominal part of the Coriolis centripetal force matrix of the ship motion model; represents the nominal part of the damping matrix of the ship motion model; The inertia matrix representing the ship motion model; The vector representing the angular acceleration of the generalized joints of the robot; The vector representing the angular velocity of the generalized joints of the robot; The Coriolis centripetal force matrix representing the ship motion model; represents the ship control torque; Represents the external main coupled disturbance used on board a ship.

[0019] Optionally, the position deviation between the track of the tracking instruction and the reference track is expressed as:

[0020] ;

[0021] The force deviation is expressed as:

[0022] ;

[0023] ;

[0024] In the formula, Indicates force deviation; Indicates the actual contact pressure; represents the expected tracking force; Indicates stiffness; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; Indicates the position of the end effector of the robot arm; Indicates the position of the reference track; Indicates the position of the track that follows the instruction.

[0025] Optionally, the dynamic force tracking error is expressed as:

[0026] ;

[0027] ;

[0028] In the formula, represents the dynamic force tracking error; Indicates stiffness; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; Indicates the position of the reference track; represents the expected tracking force; represents the impedance controlled model; represents the mass matrix; represents the damping matrix; represents the stiffness matrix.

[0029] Optionally, the stable force tracking result is the result when the dynamic force tracking error is zero, and the reference track is expressed as:

[0030] .

[0031] Optionally, the new impedance control model is expressed as:

[0032] ;

[0033] In the formula, represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the acceleration of the trajectory following the instruction; It represents the acceleration of the end effector of the manipulator approaching the docking contact surface between the UAV to be landed; Indicates the speed of the track following the instruction; It indicates the speed of the end effector of the robot arm approaching the docking contact surface between the UAV to be landed; The position of the track indicating the tracking instruction; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; Indicates force deviation.

[0034] Optionally, the new stable force tracking result is the result when the stiffness of the new impedance control model is zero. At this time, the new impedance control model is expressed as:

[0035] ;

[0036] In the formula, represents the expected tracking force; represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the track of the tracking instruction; Indicates the location of the docking contact surface between the end effector of the robotic arm and the UAV to be landed.

[0037] Optionally, the adaptive variable impedance contact force controller is expressed as:

[0038] ;

[0039] In the formula, represents the preset expected tracking force; represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the acceleration of the trajectory following the instruction; It represents the acceleration of the end effector of the manipulator approaching the docking contact surface between the UAV to be landed; Indicates the speed of the track following the instruction; It indicates the speed of the end effector of the robot arm approaching the docking contact surface between the UAV to be landed; The position of the track indicating the tracking instruction; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; represents the damping coefficient; represents the adaptive adjustment function; represents an intermediate variable; represents the adaptive regulation function after the time delay corresponding to the sampling frequency; Indicates the sampling update rate of the control system; represents the value of the expected tracking force after the time delay corresponding to the sampling frequency; represents the value of the actual contact force after the time delay corresponding to the sampling frequency; Indicates time; Indicates the sampling frequency.

[0040] Beneficial Effects

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention aims at the docking force problem of the UAV shipborne mechanical arm in a dynamic non-structural environment, and proposes a method of directly outputting the joint torque of the mechanical arm and estimating the disturbance force. Compared with the traditional impedance control method which can only suppress the disturbance force in the workspace by adjusting the position bias, the response time and speed are faster, which helps to improve the safety of autonomous recovery and landing of the UAV, and reliably realizes the landing of the shipborne UAV; the proposed adaptive variable impedance contact force controller can adaptively adjust the stiffness of the docking contact surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic flow chart of a method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV in one embodiment of the present invention;

[0044] Figure 2 The figure shows a control framework schematic diagram of a method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV in one embodiment of the present invention;

[0045] Figure 3 Shown is a schematic diagram of a coordinate system of a shipborne mechanical arm of the present invention in one embodiment;

[0046] Figure 4 The figure shows a schematic diagram of docking between a ship-borne mechanical arm and a UAV to be landed in one embodiment of the present invention;

[0047] Figure 5 It is a schematic diagram of the control framework of another embodiment of the method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to the present invention;

[0048] Figure 6 It is a schematic diagram of position tracking simulation results of a method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to the present invention in one embodiment;

[0049] Figure 7 It is a schematic diagram of the force tracking simulation results of the shipborne mechanical arm grabbing and docking force control method for assisting the landing of the UAV in one embodiment of the present invention. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention. The embodiments of the present invention and the technical features in the embodiments may be combined with each other unless there is a conflict.

[0051] The term "and / or" is only a description of the association relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " generally indicates that the related objects are in an "or" relationship.

[0052] Example 1

[0053] like Figure 1 As shown, this embodiment introduces a method for controlling the grabbing and docking force of a ship-borne mechanical arm to assist the landing of a UAV. The control framework is as follows Figure 2 As shown, the specific steps include:

[0054] The dynamic model of the ship-borne mechanical arm and the ship motion model are established. The coordinate systems of the dynamic model of the ship-borne mechanical arm and the ship motion model are as follows: Figure 3 shown.

[0055] represents the inertial coordinate system, represents the ship coordinate system with the ship's center of mass as the origin. In addition, , , Respectively represent the center points of the circle with the manipulator’s shoulder joint, elbow joint, and wrist joint as the center, Represents the position of the end effector of the manipulator. Using the Newton-Euler iteration method and the Denavit-Hartenberg transformation law of rigid bodies, the dynamic model of the shipborne manipulator is established, which is expressed as:

[0056] ;

[0057] In the formula, represents the inertial mass of the end effector of the robot arm; The vector representing the generalized joint coordinate angles of the robot arm, namely the shoulder joint angular velocity, elbow joint angular velocity and wrist joint angle; represents the Coriolis force matrix of the robot arm; The vector representing the angular acceleration of the generalized joints of the robot; The vector representing the angular velocity of the generalized joints of the robot; represents the gravitational torque of the robot arm; represents the inertia matrix of the ship; Represents the acceleration vector of the ship in the hull coordinate system; Represents the velocity vector of the ship in the hull coordinate system; represents the Coriolis force of the ship; Represents the driving torque of the robot joint; represents the disturbance caused by the friction of the robot joint; Represents the workspace position of the robot end effector in the inertial coordinate system; represents the Jacob matrix of the ship; Represents the Jacob matrix of the robot arm; represents the state vector; represents the position of the ship in the inertial coordinate system; ; Represents the inertial force and centripetal force generated on the end effector of the manipulator due to the motion of the ship.

[0058] In the inertial coordinate system, based on the dynamic main interference source, the dynamic main coupling force is defined in the forward, rolling and yaw plane motions, and the ship motion model can be written as:

[0059] ;

[0060] In the formula, Indicates the rate of change of ship position; Indicates the position of the ship in the inertial coordinate system; represents the rotation matrix of the ship, represents the yaw angle; represents the nominal part of the inertia matrix of the ship motion model; represents the nominal part of the Coriolis centripetal force matrix of the ship motion model; represents the nominal part of the damping matrix of the ship motion model; The inertia matrix representing the ship motion model; A vector representing the angles of the robot arm's joint coordinates; The Coriolis centripetal force matrix representing the ship motion model; represents the ship control torque; represents the external main coupled disturbance used on board the ship; Represents the inertial and centripetal forces acting on the ship due to the movement of the manipulator.

[0061] The dynamic model of the ship-borne manipulator and the ship motion model are established. The goal is to control the position of the end effector of the ship-borne manipulator and track the zero force so that the UAV can be docked smoothly in the docking space, such as Figure 4 The figure shows a docking diagram between a ship-borne mechanical arm and a UAV to be landed. The position of the mechanical arm end effector is controlled by using the ship-borne mechanical arm dynamic model and the ship motion model, and the ship-borne mechanical arm dynamic model receives the track of the tracking instruction.

[0062] Since there is a position deviation between the position of the end effector of the robot arm and the reference track, there is a position deviation between the track of the tracking instruction and the reference track, and the position deviation is obtained according to the position of the end effector of the robot arm, the track of the tracking instruction and the preset reference track.

[0063] in, Indicates the position of the end effector of the robot arm With expected position The difference, at this time, ; Indicates the position of the end effector of the robot arm; Indicates the position of the reference track; Indicates the position of the track following the instruction. For position control, Usually the conditions are met and the position deviation can be written as:

[0064] ;

[0065] According to the position of the end effector of the robot arm and the position of the drone to be landed, the actual contact pressure of the docking contact surface is obtained; according to the actual contact pressure and the preset expected tracking force, the force deviation is obtained.

[0066] The impedance models of the end effector of the robot arm and the drone to be landed can be simplified to a second-order spring system and a first-order spring system, respectively. Assume that the first-order stiffness is , the actual contact pressure of the butt joint can be written as:

[0067] ;

[0068] in, It represents the position of the docking contact surface between the end effector of the manipulator and the UAV to be landed, and the force is zero. It can be obtained by the six-dimensional force sensor in the actual docking model. Assume that the expected tracking force is , the force deviation between the expected tracking force and the actual contact force can be written as:

[0069] .

[0070] for Figure 5 The control framework in represents the joint angle of the robot arm, and the input force deviation is , the output is the position deviation , the impedance control model is obtained according to the position deviation and force deviation. For the conduction (position-based impedance) control model, the second-order transfer function of the impedance control model can be written as:

[0071] ;

[0072] The position deviation and force deviation It can be written as a second-order differential system of "mass damper spring":

[0073] ;

[0074] in, represents the mass matrix; represents the damping matrix; represents the stiffness matrix.

[0075] can be written as:

[0076] ;

[0077] The impedance control model is used to calculate the dynamic force tracking error, and the force tracking result when stable is obtained according to the dynamic force tracking error. The dynamic force tracking error is expressed as:

[0078] ;

[0079] The derivation process is as follows:

[0080] ;

[0081] can be written as:

[0082] ;

[0083] The stable force tracking result is the result when the dynamic force tracking error is zero, that is, , then the reference track needs to meet the following conditions:

[0084] .

[0085] It can be seen that in the known and On the premise of The force acting on the robot is zero, so the ideal force tracking effect can be achieved. However, the exact position and stiffness of the environmental contact surface are difficult to obtain. In addition, even if the environmental position and environmental stiffness are compensated, it is still difficult to achieve zero force tracking. Based on this, when the stiffness of the docking contact surface is unknown, it is difficult to obtain the precise position of the reference track after the end effector of the robot arm contacts and deforms. ,at this time, use Instead, the new position deviation is:

[0086] ;

[0087] The new impedance control model is obtained, which is expressed as:

[0088] ;

[0089] in , only when The equation is satisfied when the end effector of the ship-borne manipulator is in rigid contact with the surface of the drone with zero force, which is true under any environmental stiffness.

[0090] when Only when When , the condition of the equation is not satisfied, that is The new stable force tracking result is calculated according to the new impedance control model. The new stable force tracking result is the result when the stiffness of the new impedance control model is zero. In order to control the dynamic force tracking error in the stable state , assuming , then the new impedance control model can be written as:

[0091] ;

[0092] in , the new impedance control model is rewritten as:

[0093] .

[0094] In order to adaptively adjust and compensate for the influence of continuous change of contact surface stiffness, an adaptive variable impedance contact force controller is proposed, which is expressed as:

[0095] ;

[0096] In the formula, represents the damping coefficient; represents the adaptive adjustment function; represents an intermediate variable; represents the adaptive regulation function after the time delay corresponding to the sampling frequency; Indicates the sampling update rate of the control system; represents the value of the expected tracking force after the time delay corresponding to the sampling frequency; represents the value of the actual contact force after the time delay corresponding to the sampling frequency; Indicates time; Indicates the sampling frequency.

[0097] Example 2

[0098] This embodiment introduces a specific experimental design of a method for controlling the grabbing and docking force of a ship-borne mechanical arm to assist in landing a UAV, including the following steps:

[0099] The simulation was performed based on the one-dimensional physical parameters listed in Table 1.

[0100] Table 1 Parameters based on one-dimensional docking force control

[0101]

[0102] The initial position of the drone waiting to land is adjusted to =0.05m; the initial position of the end effector of the robot arm on the z-axis is adjusted to =0.025m; the contact force is simplified to the pressure of the end effector of the robot arm in the vertical direction of the z-axis; the docking speed of the end effector of the robot arm is adjusted to = 0.05m / s. When the pressure tracks to the desired constant force, the motion of the end effector of the robot arm must be stopped; the reason is that excessive contact pressure will cause the drone to crash while hovering.

[0103] Based on the conditions in Table 1, the position tracking simulation results and force tracking simulation results using the proposed control method are shown in Table 1. Figure 6 , 7 As shown in the figure. According to the simulation results, the linear motion distance from the vertical direction of the z-axis of the robot end effector to the stop of pressing is about 0.005m. This short distance of motion results in negligible changes in the angles of each robot joint obtained by inverse kinematics at the beginning of pressing. = 0.5s, the operating manipulator and the lock button begin to contact, and after a short adjustment, the pressing pressure stabilizes at 5 N. In addition, for the docking process between the shipborne manipulator and the UAV, a suitable expected constant pressing force value can be given to avoid possible damage to the UAV caused by overload contact force.

[0104] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0105] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0106] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0108] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV, characterized in that: The position of the end effector of the mechanical arm is controlled by using the established shipboard mechanical arm dynamic model and the ship motion model, and the shipboard mechanical arm dynamic model receives the track of the tracking instruction, and the method includes: Obtaining a position deviation between the track of the tracking instruction and the reference track according to the position of the end effector of the robot arm, the track of the tracking instruction and a preset reference track; According to the position of the end effector of the robot arm and the position of the drone to be landed, an actual contact pressure of the docking contact surface is obtained; according to the actual contact pressure and a preset expected tracking force, a force deviation is obtained; An impedance control model is obtained according to the position deviation and the force deviation, a dynamic force tracking error is calculated using the impedance control model, and a stable force tracking result is obtained according to the dynamic force tracking error.

2. The method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to claim 1 is characterized in that: When the stiffness of the docking contact surface between the end effector of the manipulator and the unmanned aerial vehicle to be landed cannot be obtained, the position of the docking contact surface is used as a reference track to obtain a new impedance control model; Calculating a new stable force tracking result according to the new impedance control model; According to the new stable force tracking result, an adaptive variable impedance contact force controller is obtained, which is used to adaptively adjust the stiffness of the butt contact surface.

3. The method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to claim 1 is characterized in that: The dynamic model of the robotic arm is expressed as: ； In the formula, represents the inertial mass of the end effector of the robot arm; The vector representing the angular acceleration of the generalized joints of the robot; The vector representing the angular velocity of the generalized joints of the robot; represents the Coriolis force matrix of the robot arm; represents the gravitational torque of the robot arm; represents the inertia matrix of the ship; Represents the acceleration vector of the ship in the hull coordinate system; Represents the velocity vector of the ship in the hull coordinate system; represents the Coriolis force of the ship; Represents the driving torque of the robot joint; represents the disturbance caused by the friction of the robot joint; Represents the workspace position of the robot end effector in the inertial coordinate system; represents the Jacob matrix of the ship; Represents the Jacob matrix of the robotic arm.

4. The method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to claim 1 is characterized in that: The ship motion model is expressed as: ； In the formula, Indicates the rate of change of ship position; represents the rotation matrix of the ship; Represents the acceleration vector of the ship in the hull coordinate system; Represents the velocity vector of the ship in the hull coordinate system; represents the nominal part of the inertia matrix of the ship motion model; represents the nominal part of the Coriolis centripetal force matrix of the ship motion model; represents the nominal part of the damping matrix of the ship motion model; The inertia matrix representing the ship motion model; The vector representing the angular acceleration of the generalized joints of the robot; The vector representing the angular velocity of the generalized joints of the robot; The Coriolis centripetal force matrix representing the ship motion model; represents the ship control torque; Represents the external main coupled disturbance used on board a ship.

5. The method for controlling the grabbing and docking force of a shipborne mechanical arm for assisting the landing of a UAV according to claim 1, characterized in that: The position deviation between the track of the tracking instruction and the reference track is expressed as: ； The force deviation is expressed as: ； ； In the formula, Indicates force deviation; Indicates the actual contact pressure; represents the expected tracking force; Indicates stiffness; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; Indicates the position of the end effector of the robot arm; Indicates the position of the reference track; Indicates the position of the track that follows the instruction.

6. The method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to claim 1, characterized in that: The dynamic force tracking error is expressed as: ； ； In the formula, represents the dynamic force tracking error; Indicates stiffness; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; Indicates the position of the reference track; represents the expected tracking force; represents the impedance controlled model; represents the mass matrix; represents the damping matrix; represents the stiffness matrix.

7. The method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to claim 6 is characterized in that: The stable force tracking result is the result when the dynamic force tracking error is zero. At this time, the reference track is expressed as: 。 8. The method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to claim 2, characterized in that: The new impedance control model is expressed as: ； In the formula, represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the acceleration of the trajectory following the instruction; It represents the acceleration of the end effector of the manipulator approaching the docking contact surface between the UAV to be landed; Indicates the speed of the track following the instruction; It indicates the speed of the end effector of the robot arm approaching the docking contact surface between the UAV to be landed; The position of the track indicating the tracking instruction; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; Indicates force deviation.

9. The method for controlling the grabbing and docking force of a ship-borne mechanical arm for assisting the landing of a UAV according to claim 2, characterized in that: The new stable force tracking result is the result when the stiffness of the new impedance control model is zero. At this time, the new impedance control model is expressed as: ； In the formula, represents the expected tracking force; represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the acceleration of the trajectory following the instruction; It represents the acceleration of the end effector of the manipulator approaching the docking contact surface between the UAV to be landed; Indicates the speed of the track following the instruction; It indicates the speed of the end effector of the robot arm approaching the docking contact surface between the UAV to be landed; The position of the track indicating the tracking instruction; Indicates the location of the docking contact surface between the end effector of the robotic arm and the UAV to be landed.

10. The method for controlling the grabbing and docking force of a shipborne mechanical arm for assisting the landing of a UAV according to claim 2, characterized in that: The adaptive variable impedance contact force controller is expressed as: ； In the formula, represents the preset expected tracking force; represents the mass matrix; represents the damping matrix; represents the stiffness matrix; represents the acceleration of the trajectory following the instruction; It represents the acceleration of the end effector of the manipulator approaching the docking contact surface between the UAV to be landed; Indicates the speed of the track following the instruction; It indicates the speed of the end effector of the robot arm approaching the docking contact surface between the UAV to be landed; The position of the track indicating the tracking instruction; Indicates the position of the docking contact surface between the end effector of the robotic arm and the UAV to be landed; represents the damping coefficient; represents the adaptive adjustment function; represents an intermediate variable; represents the adaptive regulation function after the time delay corresponding to the sampling frequency; Indicates the sampling update rate of the control system; represents the value of the expected tracking force after the time delay corresponding to the sampling frequency; represents the value of the actual contact force after the time delay corresponding to the sampling frequency; Indicates time; Indicates the sampling frequency.

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