End actuating mechanism of overhead working truck and control method of end actuating mechanism

Abstract

The invention discloses a tail end executing mechanism of an overhead working truck and a control method of the tail end executing mechanism, the tail end executing mechanism comprises an upper platform and a chassis which are coaxially arranged up and down, three through holes are formed in the chassis, the included angle between every two through holes is 120 degrees, and the distances from the through holes to the center of the chassis are equal; a lower electric cylinder is arranged in each through hole, the upper end of a cylinder barrel of each lower electric cylinder is rotationally connected into the corresponding through hole, and the rotating axis passes through the center of the base plate; an upper electric cylinder is arranged at the upper end of each lower electric cylinder, the upper end of a cylinder rod of each lower electric cylinder is rotationally connected with a base of the corresponding upper electric cylinder, and the rotating axis is perpendicular to the rotating axis of the corresponding lower electric cylinder; the upper end of a cylinder rod of the upper electric cylinder is connected to the bottom face of the upper platform through hooke hinges, the orientation of the three hooke hinges is consistent with the orientation of the three through holes in the base plate, and the distances between the hooke hinges and the center of the upper platform are equal. The chassis is mounted at the tail end of the overhead working truck; the actuator tool is installed on the upper platform. The device is good in adaptability with the overhead working truck, high in degree of freedom utilization rate and low in cost.

Description

Technical Field

[0001] The invention relates to an aerial work vehicle, and in particular to a terminal execution mechanism of the aerial work vehicle and a control method thereof. Background Art

[0002] The end effector of the aerial work vehicle is its key component, responsible for completing specific work tasks, such as spraying on the surface of the hull. The end effector of the aerial work vehicle usually adopts a serial six-degree-of-freedom robotic arm, such as the technical solution disclosed in CN2133910071U. It is not only costly, but also the six-degree-of-freedom robotic arm will be affected by the aerial work vehicle arm when working, resulting in the restriction of some joint movements. Secondly, the robotic arm only needs 3 to 4 degrees of freedom to perform simple tasks such as spraying. At this time, some of the six degrees of freedom are not fully utilized, the degree of freedom utilization rate is low, and there is a waste of degrees of freedom. Summary of the invention

[0003] Purpose of the invention: The first purpose of the present invention is to provide an end effector mechanism with low cost and good compatibility with aerial work vehicles; the second purpose of the present invention is to provide a control method for the end effector mechanism.

[0004] Technical solution: The end actuator of an aerial work vehicle of the present invention comprises an upper platform and a chassis which are coaxially arranged up and down, three through holes are provided on the chassis, the angle between any two of the through holes is 120°, and the distance from each through hole to the center of the chassis is equal; a lower electric cylinder is provided in each through hole, and the upper end of the cylinder barrel of the lower electric cylinder is rotatably connected to the through hole, and the rotation axis passes through the center of the chassis; an upper electric cylinder is provided on the upper end of each lower electric cylinder, and the upper end of the cylinder rod of the lower electric cylinder is rotatably connected to the base of the upper electric cylinder, and the rotation axis is perpendicular to the rotation axis of the lower electric cylinder; the upper end of the cylinder rod of the upper electric cylinder is connected to the bottom surface of the upper platform through a Hook's hinge, the directions of the three Hook's hinges are consistent with the three through holes on the chassis, and the distances from each Hook's hinge to the center of the upper platform are equal; the chassis is installed at the end of the aerial work vehicle; the actuator tool is installed on the upper platform.

[0005] Furthermore, a central through hole is formed on the upper platform, and the actuator tool passes through the central through hole and is fixed on the upper platform by three clamps, and the three clamps are distributed in a triangular shape.

[0006] Furthermore, a push rod is threadedly connected to the clamp, the outer end of the push rod has a hexagonal handle, and the inner end has an arc block; when the hexagonal handle is rotated, the push rod can move along the axial direction; the three push rods clamp the actuator tool from three directions.

[0007] Furthermore, a threaded hole is provided at the center of the chassis, which is fixedly connected to the end of the aerial work vehicle by bolts.

[0008] Furthermore, a U-shaped connector is fixed to the end of the cylinder rod of the lower electric cylinder, a bolt is fixed to the U-shaped connector, and a roller bearing is sleeved on the bolt; the base of the upper electric cylinder is fixedly connected to the roller bearing sleeved on the bolt.

[0009] The control method of the terminal actuator of the aerial work vehicle of the present invention comprises:

[0010] (1) Establish a coordinate system for the end effector, determine the coordinates of the three Hooke's hinges through DH coordinate transformation, and then determine the coordinates of the center position of the upper platform;

[0011] (2) According to the coordinates of the center position of the upper platform, the extensions of the three upper electric cylinders {l1, l2, l3} are inversely solved to determine the limit position of the center of the upper platform to determine the working range of the upper platform, and the expected position P of the center of the upper platform is determined within the working range. d =[X d ,Y d ,Z d ] T , and then inversely solve the extensions of the three lower electric cylinders {l4,l5,l6} according to the expected position to ensure that the moving path of the upper platform is correct;

[0012] (3) The inclination angle and extension of each electric cylinder are detected in real time, the deviation between the actual position and the expected position is calculated, and the trajectory is controlled using an adaptive PID control strategy.

[0013] Furthermore, an absolute coordinate system XOY is established with the center of the chassis as the origin O, the vertical direction as the Z axis, the horizontal direction along the right electric cylinder as the Y axis, and the horizontal direction perpendicular to this direction as the X axis; a relative coordinate system xoy is established with the center of the three Hooke's hinge rotation positions as the origin o, the horizontal direction of the right electric cylinder as the y axis, and the horizontal direction perpendicular to this direction as the x axis;

[0014] The coordinate points A, B, and C of the three Hooke's hinges in the absolute coordinate system are (x, y, z), (x', y', z'), and (x", y", z");

[0015] The coordinate expression of point A(x,y,z) is:

[0016]

[0017] Wherein, L is the length of the upper electric cylinder; s is sinα, α is the angle between the upper electric cylinder and the absolute coordinate plane in the normal state, and sinα is a constant; θ1 is the rotation angle between the absolute coordinate plane and the lower electric cylinder; c is cosα, also a constant; θ2 is the rotation angle between the upper electric cylinder and the lower electric cylinder;

[0018] Simplified to:

[0019]

[0020] Among them, ΔL is the length of the upper electric cylinder and the extension of the cylinder rod; Δp is the extension of the cylinder rod of the lower electric cylinder;

[0021] Point A, point B and point C are symmetrical in an equilateral triangle about the origin o in space;

[0022] The coordinates of the center position of the upper platform (x0, y0, z0) are expressed by the coordinates of three points A, B, and C:

[0023]

[0024] constraint:

[0025]

[0026] Where Z is the vertical distance from the center of the upper platform to the origin o.

[0027] Furthermore, the working range of the upper platform is determined by R, D, and r:

[0028]

[0029] Wherein, R represents the distance from the center of the upper platform to the absolute coordinate origin O when the upper electric cylinder on one side rotates to the left limit position; S is the distance from the axis of the lower electric cylinder to the center of the chassis; L is the length of the upper electric cylinder; Q is the distance between the Hooke's hinge and the center of the upper platform; γ is the angle between the upper electric cylinder on one side and the horizontal direction of the chassis;

[0030]

[0031] Where r represents the distance from the center of the upper platform to the absolute coordinate origin O when the extension of the lower electric cylinder on one side is the largest; P is the extension of the lower electric cylinder push rod;

[0032] D represents the distance from the center of the upper platform to the absolute coordinate origin O.

[0033] Furthermore, the working range angle of the upper platform is β, and the angle of β is determined by the rotation angle of the Hooke's hinge; the maximum moving range of the upper platform is (L+maxΔL)sinα, where α is the angle between the upper electric cylinder and the chassis, and α changes with the change of the electric cylinder elongation ΔL; the vertical direction change range of the upper platform is [0, (L+maxΔL)sinα].

[0034] Furthermore, the adaptive PID control strategy is:

[0035]

[0036] Among them, u i is the control signal applied to the i-th electric cylinder, K p, K i , K d They are proportional, integral, and differential gain, respectively; e i is the position error.

[0037] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0038] (1) Good compatibility with aerial work vehicles. The present invention provides a parallel end-effector with a large working space and range of motion and high flexibility. After being connected to the end of the aerial work vehicle, it is subject to fewer constraints during operation than a serial six-DOF robot arm, and the motion joints are not affected by the constraints of the aerial work vehicle.

[0039] (2) The end effector can provide six degrees of freedom, which can be fully utilized even when performing simple tasks such as spraying, and is cheaper than a serial six-degree-of-freedom robot arm.

[0040] (3) Good stability. The parallel end effector has the advantages of strong load-bearing capacity, high rigidity and low inertia.

[0041] (4) The control method of the end effector can accurately control the end movement trajectory and better adapt to operational requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a structural diagram of the end effector;

[0043] Figure 2 This is a bottom view of the upper platform;

[0044] Figure 3 It is a structural diagram of the end actuator installed at the end of the aerial work vehicle;

[0045] Figure 4 It is a schematic diagram of establishing a coordinate system on the end effector;

[0046] Figure 5 (b) is the normal position of the end actuator, Figure 5 (a) and Figure 5 (c) are the two extreme positions of the end actuator, where Figure 5 (a) The electric cylinder on the lower side is in the initial state. Figure 5 (c) The electric cylinder on the lower middle side is in the extreme extension state;

[0047] Figure 6 The upper platform is Figure 5 Schematic diagram of the trajectory between the three locations shown;

[0048] Figure 7It is a forward schematic diagram of the upper platform in the normal position and two extreme positions;

[0049] Figure 8 It is a schematic diagram of the positive angular orientation of the upper platform;

[0050] Fig. 9 It is a schematic diagram of the working range of the end actuator;

[0051] Fig.10 It is the PID control strategy of the electric cylinder;

[0052] Fig.11 It is a flow chart of the control method of the terminal actuator;

[0053] Fig.12 It is a schematic diagram of the straight line spraying path;

[0054] Fig.13 It is a schematic diagram of the arc spraying path. DETAILED DESCRIPTION

[0055] The present invention will be further described below in conjunction with the accompanying drawings.

[0056] Attached Figures 1 to 13 The reference numerals in the figures are as follows:

[0057] 1-1, upper platform; 1-2, clamp; 1-3, Hook hinge; 1-4, upper electric cylinder; 1-5, U-shaped connector; 1-6, chassis; 1-7, lower electric cylinder; 1-8, bolt; 1-9, actuator tool; 1-10, hexagonal handle; 1-11, countersunk bolt; 1-12, push rod.

[0058] like Figure 1 As shown, an embodiment of the present invention provides an end actuator of an aerial work vehicle, including an upper platform 1-1 and a chassis 1-6 coaxially arranged up and down, a threaded hole is arranged at the center of the chassis 1-6, and is fixedly connected to the end of the aerial work vehicle by bolts to ensure that the chassis 1-6 is absolutely stationary relative to the entire end actuator, such as Figure 3 The end effector is rotated with the help of the turntable of the aerial work vehicle.

[0059] Three through holes are provided on the chassis 1-6, and the angle between two through holes is 120°. The distance between each through hole and the center of the chassis 1-6 is equal. A lower electric cylinder 1-7 is provided in each through hole, and the upper end of the cylinder barrel of the lower electric cylinder 1-7 is rotatably connected to the through hole through a rotating shaft, and the rotation axis passes through the center of the chassis 1-6. A U-shaped connector 1-5 is fixed to the end of the cylinder rod of the lower electric cylinder 1-7, and a bolt 1-8 is fixed to the U-shaped connector 1-5. A roller bearing is sleeved on the bolt 1-8, and the bolt 1-8 is perpendicular to the rotation axis of the lower electric cylinder 1-7. An upper electric cylinder 1-4 is provided on the upper end of each lower electric cylinder 1-7, and the base of the upper electric cylinder 1-4 is fixedly connected to the roller bearing sleeved on the bolt 1-8.

[0060] Combination Figure 2 The upper end of the cylinder rod of the upper electric cylinder 1-4 is connected to the bottom surface of the upper platform 1-1 through the thread on the Hook's hinge 1-3. The orientation of the three Hook's hinges 1-3 is consistent with the three through holes on the chassis 1-6. The three threaded connections of the upper platform 1-1 are 120° in each pair, and the distances from each Hook's hinge 1-3 to the center of the upper platform 1-1 are equal. The rotation range of the Hook's hinge 1-3 itself is 0 to 180°.

[0061] The lower electric cylinder 1-7 is initially perpendicular to the chassis 1-6, while the upper electric cylinder 1-4 is at a fixed angle to the chassis 1-6, and the extension of the lower electric cylinder 1-7 is only two-thirds of the extension of the upper electric cylinder 1-4.

[0062] A clamp 1-2 is installed in the middle position of the two Hooke hinges 1-3 through a countersunk bolt 1-11, and the three clamps 1-2 are distributed in a triangle. A push rod 1-12 is threadedly connected to the clamp 1-2, and the outer end of the push rod 1-12 has a hexagonal handle 1-10, and the inner end has an arc block. When the hexagonal handle 1-10 is turned, the push rod 1-12 can move along the axial direction. A through hole is left in the center of the upper platform 1-1, and the actuator tool 1-9 passes through the central through hole. The three push rods 1-12 clamp the actuator tool 1-9 from three directions.

[0063] The embodiment of the present invention also provides a control method for the end actuator of the aerial work vehicle according to the embodiment of the present invention, comprising the following steps:

[0064] (1) Establishing a coordinate system for the end effector, determining the coordinates of the three Hooke's hinges 1-3 through DH coordinate transformation, and then determining the coordinates of the center position of the upper platform 1-1;

[0065] Figure 4 The figure shows the normal position of the end actuator, with the center position of the chassis 1-6 as the origin O, the vertical direction as the Z axis, the horizontal direction along the right electric cylinder as the Y axis, and the horizontal direction perpendicular to this direction as the X axis, establishing an absolute coordinate system XOY.

[0066] With the center of the rotation position of the three Hooke's hinges 1-3 as the origin o, the horizontal direction of the right electric cylinder as the y-axis, and the horizontal direction perpendicular to this direction as the x-axis, a relative coordinate system xoy is established.

[0067] The coordinate points A, B, and C of the three Hooke's hinges 1-3 in the absolute coordinate system are (x, y, z), (x', y', z'), and (x", y", z").

[0068] According to the DH coordinate establishment rules, the rods related to point A are determined to be the upper electric cylinder 1-4, the lower electric cylinder 1-7, the intersection of the two electric cylinders and the absolute coordinate system XOY. After determining the connecting rod and the joint, the relative coordinate system is established to produce the DH parameters. Through coordinate transformation, including rotation transformation and translation transformation, the coordinate expression of point A (x, y, z) is obtained as follows:

[0069]

[0070] Where, L is the length of the upper electric cylinder; s is sinα, α is the angle between the upper electric cylinder and the absolute coordinate plane in the normal state, and sinα is a constant; θ1 is the rotation angle between the absolute coordinate plane and the lower electric cylinder, and the normal state is 90°; c is cosα, which is also a constant; θ2 is the rotation angle between the upper electric cylinder and the lower electric cylinder.

[0071] The extension and retraction of the upper electric cylinder push rod directly affects the coordinate of point A, and the extension and retraction of the lower electric cylinder push rod directly affects the coordinate z of point A, and indirectly affects the coordinates x and y.

[0072] The formula simplifies to:

[0073]

[0074] Among them, ΔL is the length of the upper electric cylinder itself and the extension and contraction of the cylinder rod; Δp is the extension and contraction of the cylinder rod of the lower electric cylinder.

[0075] like Figure 4 , point A, point B and point C are equilaterally symmetrical about the origin o in space. In this coordinate system, the relative positions of the coordinates of the three points are fixed, that is, the coordinate expressions of point B and point C are almost the same as those of point A. The difference is that the joint rotation angle θ corresponding to the absolute coordinate system of each point and the relative coordinate of the lower electric cylinder is different.

[0076] The coordinates of the center position of the upper platform (x0, y0, z0) are expressed by the coordinates of three points A, B, and C:

[0077]

[0078] constraint:

[0079]

[0080] Where Z is the vertical distance from the center of the upper platform to the origin o.

[0081] (2) According to the coordinates of the center position of the upper platform, the extensions of the three upper electric cylinders {l1, l2, l3} are inversely solved to determine the limit position of the center of the upper platform to determine the working range of the upper platform, and the expected position P of the center of the upper platform is determined within the working range. d =[X d ,Y d ,Z d ] T , and then inversely solve the extensions of the three lower electric cylinders {l4,l5,l6} according to the expected position to ensure that the moving path of the upper platform is correct;

[0082] The working range of the upper platform is determined by the following method:

[0083] like Figure 5 The figure shows a schematic diagram of one side of the electric cylinder reaching the limit position. Figure 5 In (a), the arc is rotated with bolt 1-8 as the center and the rotation radius is R. The elongation of the upper electric cylinder push rod is 0, and the two lower electric cylinders on the right have a certain elongation. Figure 5 (a) Calculate:

[0084]

[0085] Among them, R means when the upper electric cylinder on one side rotates to the left limit position, the center of the upper platform reaches Figure 6 The distance between the absolute coordinate origin O in the figure; S is the distance between the axis of the lower electric cylinder and the center of the chassis; L is the length of the upper electric cylinder; Q is the distance between the center of the Hooke's hinge and the upper platform; γ is the angle between the upper electric cylinder on one side and the horizontal direction of the chassis.

[0086] Figure 5 In (b), the instantaneous rotation radius of the platform center is the distance D from the platform to the chassis. Figure 5 In (c), the extension of the lower left electric cylinder push rod is the largest, the extension of the three upper electric cylinder push rods is 0, and the extension of the two lower right electric cylinder push rods is 0. Figure 5 (c) Calculate:

[0087]

[0088] Among them, r represents the distance from the center of the upper platform to the maximum when the electric cylinder on one side is extended to the maximum. Figure 6 The distance from the absolute coordinate origin O in the figure; P is the extension of the electric cylinder push rod below.

[0089] Figure 5 In the figure, the dotted line is the trajectory of the center position of the upper platform when the upper electric cylinder and the platform are kept relatively stationary. The upper platform is driven by the upper electric cylinder to face the extreme position of the diagonal direction. Figure 7shown.

[0090] like Figure 8 As shown in the figure, the working range angle of the upper platform is β, and the angle of β is determined by the rotation angle of the Hooke's hinge. The maximum moving range of the upper platform is (L+maxΔL)sinα, where α is the angle between the upper electric cylinder and the chassis. When the electric cylinder elongation ΔL changes, α also changes accordingly; the vertical direction change range of the upper platform is [0, (L+maxΔL)sinα], and the two-dimensional working space of the entire mechanism is as follows Fig. 9 shown.

[0091] like Fig.10 As shown in the figure, in the initial state, the upper platform moves at a speed v while being parallel to the spray target. During the platform movement, the upper platform remains parallel to the spray target. The three electric cylinders above are located according to the desired position P of the platform center. d =[X d ,Y d ,Z d ] T , solve the length {l1,l2,l3} that each upper electric cylinder should be adjusted to. Taking the linear model as an example, the platform obtains contributions in the X, Y and Z directions, and the inverse kinematics equation can be simplified to:

[0092]

[0093] Among them, k i 、j i , g i are the coefficients related to the contribution of the change in length of the cylinder i to the X, Y and Z positions of the platform.

[0094]

[0095] Among them, Li is the length of six cylinders; P ix , P iy , P iz is the coordinate value of the 6 moving points on the upper platform, B ix , B iy , B iz is the initial coordinate value of the following 6 static points. The 6 moving points include the 6 points at the ends of the 6 electric cylinder push rods, and the 6 static points include the 6 points at the ends of the 6 electric cylinder bases. The 6 static points are relative static points, including 3 static points relative to the three electric cylinders above and 3 static points relative to the three electric cylinders below. The lengths of the six electric cylinders are calculated by the coordinates of the moving points and the static points.

[0096] The three electric cylinders below are located according to the desired position P of the platform. d, solve the length {l4,l5,l6} that each lower electric cylinder should be adjusted to. Here, the solution equation group using the spatial position point A is solved, and the expected position coordinates and the elongation of the lower electric cylinder are solved by analytical method. The nonlinear inverse kinematics equation group can be expressed as:

[0097]

[0098] Where f(·) is the nonlinear mapping function from the connecting rod length to the platform displacement.

[0099] (3) The inclination angle and extension of each electric cylinder are detected in real time, the deviation between the actual position and the expected position is calculated, and the trajectory is controlled using an adaptive PID control strategy.

[0100] During the movement of the platform, the sensor device collects the actual motion state data of the mechanical system in real time, processes and analyzes the collected data, extracts useful information and calculates the deviation from the expected trajectory. At this time, the adaptive PID control strategy is adopted:

[0101]

[0102] Among them, u i is the control signal applied to the i-th electric cylinder, K p , K i , K d They are proportional, integral, and differential gain, respectively; e i is the position error.

[0103] Based on the output of the adaptive PID control algorithm, a control command for the mechanical system is generated. The control command is sent to the drive cylinder of the mechanical system, which takes corresponding actions according to the signal sent by the control and monitors the motion state of the mechanical system in real time for feedback. PID takes the data fed back by the sensor into consideration, further outputs the result, and generates a signal to send to the drive cylinder to execute the action.

[0104] The end actuator provided by the present invention is a parallel mechanical structure, which can realize a wide range of work and can be used for spraying or polishing. For example, after the mechanical end is clamped with a spray gun, it can be used for spraying the outer plate of a ship.

[0105] The aerial work robot of the terminal execution structure of the present invention is as follows Fig.11The process shown works. Step 1, parameter initialization, task start. Enter step 2, the aerial work robot uses sensors to visually scan the target outer panel, moves the body, rotates the turntable to move the connecting terminal mechanical structure to the vicinity of the target, and enters step 3 to determine whether the distance between the target and the terminal mechanical structure meets the requirements of the terminal mechanical structure. If not, adjust the aerial work robot. If it meets the requirements, enter step 4, pass the target outer panel coordinates to the terminal mechanical structure, and then enter step 5. The obtained target coordinates are calculated by the PID algorithm to further move the platform terminal to the vicinity of the target and implement the movement. Enter step 6, the platform uses radar ranging to calculate the working angle that the platform and the target should form to ensure the operation of the spray gun, and then enter step 7. The visual sensor detects the outer panel range centered on the target that is larger than the target plane, and the feedback system calculates the starting and ending points of the platform spraying path. The spray gun starts working, and the mechanical structure moves according to the planned spraying path. Go to step 8 to determine whether the end point of the current path is the final task end point. If not, go to step 9. The content of step 9 is: determine whether the platform is approaching the limit position. If so, return to step 7. The aerial work robot moves the main arm and quickly moves to the end point of the platform spraying path calculated by the feedback system. During this process, the spray gun and the platform continue to work, and the platform movement remains unchanged. The feedback system re-feeds back the starting point and end point of the spraying path, the spray gun works, and the platform moves according to the planned path; if not, the platform continues to work and returns to step 8; if the task is about to end, go to step 10, and the platform completes the remaining part of the task. Go to step 11, the feedback system feeds back information to the control unit, controls the platform to return to the initial position, and the aerial work robot exits, and finally goes to step 12, and the task ends.

[0106] Fig.12 The straight line shown is a schematic diagram of the spraying path during the spraying process. The aerial work vehicle moves the mechanical end to the target first movement starting point. The controller plans the first movement trajectory and end position and implements the command. The platform moves according to the linear interpolation method. When it is about to approach the first movement end point, the controller uses the first movement end point as the second movement starting point and plans the second movement trajectory and end position. If the distance of a single movement exceeds the platform's own limit range S, when the platform approaches the limit position, the controller calculates the moving spray trajectory in advance and issues a command to control the aerial work robot to move the mechanical end for the second movement.

[0107] Fig.13 The curve shown is a schematic diagram of the spraying path during the spraying process. The aerial work vehicle moves the mechanical end to the starting point of the first movement of the target. The controller plans the starting point, end point and circular interpolation algorithm movement path along the tangent direction of the desired curve for the first movement. During the movement, two points on the curve are continuously obtained for interpolation in the tangent direction until it moves to the end point of the curve.

Claims

1. An end effector of an aerial work vehicle, characterized in that: It comprises an upper platform and a chassis coaxially arranged up and down, three through holes are provided on the chassis, the angle between two through holes is 120°, and the distance between each through hole and the center of the chassis is equal; a lower electric cylinder is provided in each through hole, and the upper end of the cylinder barrel of the lower electric cylinder is rotatably connected to the through hole, and the rotation axis passes through the center of the chassis; an upper electric cylinder is provided on the upper end of each lower electric cylinder, and the upper end of the cylinder rod of the lower electric cylinder is rotatably connected to the base of the upper electric cylinder, and the rotation axis is perpendicular to the rotation axis of the lower electric cylinder; the upper end of the cylinder rod of the upper electric cylinder is connected to the bottom surface of the upper platform through a Hook's hinge, the directions of the three Hook's hinges are consistent with the three through holes on the chassis, and the distance between each Hook's hinge and the center of the upper platform is equal; The chassis is installed at the end of the aerial work vehicle; the actuator tool is installed on the upper platform.

2. The end effector of the aerial work vehicle according to claim 1, characterized in that: The upper platform is provided with a central through hole, the actuator tool passes through the central through hole and is fixed on the upper platform by three clamps, and the three clamps are distributed in a triangular shape.

3. The end effector of the aerial work vehicle according to claim 2, characterized in that: A push rod is threadedly connected to the clamp, and the outer end of the push rod has a hexagonal handle and the inner end has an arc block; when the hexagonal handle is turned, the push rod can move along the axial direction; the three push rods clamp the actuator tool from three directions.

4. The end effector of the aerial work vehicle according to claim 1, characterized in that: A threaded hole is provided in the center of the chassis, which is fixedly connected to the end of the aerial work vehicle by bolts.

5. The end effector of the aerial work vehicle according to claim 1, characterized in that: A U-shaped connector is fixed to the end of the cylinder rod of the lower electric cylinder, a bolt is fixed to the U-shaped connector, and a roller bearing is sleeved on the bolt; the base of the upper electric cylinder is fixedly connected to the roller bearing sleeved on the bolt.

6. A control method for the end effector of an aerial work vehicle according to claim 1, characterized in that: include: (1) Establish a coordinate system for the end effector, determine the coordinates of the three Hooke's hinges through DH coordinate transformation, and then determine the coordinates of the center position of the upper platform; (2) According to the coordinates of the center position of the upper platform, the extensions of the three upper electric cylinders {l1, l2, l3} are inversely solved to determine the limit position of the center of the upper platform to determine the working range of the upper platform, and the expected position P of the center of the upper platform is determined within the working range. d =[X d ,Y d ,Z d ] T , and then inversely solve the extensions of the three lower electric cylinders {l4,l5,l6} according to the expected position to ensure that the moving path of the upper platform is correct; (3) The inclination angle and extension of each electric cylinder are detected in real time, the deviation between the actual position and the expected position is calculated, and the trajectory is controlled using an adaptive PID control strategy.

7. The control method of the end effector according to claim 6, characterized in that: With the center of the chassis as the origin O, the vertical direction as the Z axis, the horizontal direction along the right electric cylinder as the Y axis, and the horizontal direction perpendicular to this direction as the X axis, an absolute coordinate system XOY is established; with the center of the three Hooke's hinge rotation positions as the origin o, the horizontal direction of the right electric cylinder as the y axis, and the horizontal direction perpendicular to this direction as the x axis, a relative coordinate system xoy is established; The coordinate points A, B, and C of the three Hooke's hinges in the absolute coordinate system are (x, y, z), (x', y', z'), and (x", y", z"); The coordinate expression of point A(x,y,z) is: Wherein, L is the length of the upper electric cylinder; s is sinα, α is the angle between the upper electric cylinder and the absolute coordinate plane in the normal state, and sinα is a constant; θ1 is the rotation angle between the absolute coordinate plane and the lower electric cylinder; c is cosα, also a constant; θ2 is the rotation angle between the upper electric cylinder and the lower electric cylinder; Simplified to: Among them, ΔL is the length of the upper electric cylinder and the extension of the cylinder rod; Δp is the extension of the cylinder rod of the lower electric cylinder; Point A, point B and point C are symmetrical in an equilateral triangle about the origin o in space; The coordinates of the center position of the upper platform (x0, y0, z0) are expressed by the coordinates of three points A, B, and C: constraint: Where Z is the vertical distance from the center of the upper platform to the origin o.

8. The control method of the end effector according to claim 7, characterized in that: Determine the working range of the upper platform through R, D, and r: Wherein, R represents the distance from the center of the upper platform to the absolute coordinate origin O when the upper electric cylinder on one side rotates to the left limit position; S is the distance from the axis of the lower electric cylinder to the center of the chassis; L is the length of the upper electric cylinder; Q is the distance between the Hooke's hinge and the center of the upper platform; γ is the angle between the upper electric cylinder on one side and the horizontal direction of the chassis; Where r represents the distance from the center of the upper platform to the absolute coordinate origin O when the extension of the lower electric cylinder on one side is the largest; P is the extension of the lower electric cylinder push rod; D represents the distance from the center of the upper platform to the absolute coordinate origin O.

9. The control method of the end effector according to claim 8, characterized in that: The working range angle of the upper platform is β, and the angle of β is determined by the rotation angle of the Hooke's hinge; the maximum moving range of the upper platform is (L+maxΔL)sinα, where α is the angle between the upper electric cylinder and the chassis. When the elongation ΔL of the electric cylinder changes, α also changes accordingly; the vertical direction change range of the upper platform is [0, (L+maxΔL)sinα].

10. The control method of the end effector according to claim 6, characterized in that: The adaptive PID control strategy is: Among them, u i is the control signal applied to the i-th electric cylinder, K p , K i , K d They are proportional, integral, and differential gain, respectively; e i is the position error.

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