CN114400733A

CN114400733A - Robot for automatic charging of unmanned aerial vehicle

Info

Publication number: CN114400733A
Application number: CN202111543819.9A
Authority: CN
Inventors: 许明; 苏礼荣
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2021-12-16
Filing date: 2021-12-16
Publication date: 2022-04-26

Abstract

The invention discloses a robot for automatic charging of an unmanned aerial vehicle. The robot includes an end effector and a position adjustment mechanism. The position adjusting mechanism can drive the end effector to move freely in a horizontal plane and rotate around a vertical axis. The end effector comprises a mounting plate, a charging interface, a second pressure sensor and a distance measuring sensor. Two side edges forming an included angle of 90 degrees are arranged on the mounting plate; the two sides are respectively used as a first detection side and a second detection side. The two ends of the first detection edge are provided with second pressure sensors; and distance measuring sensors are arranged in the middle positions of the first detection edge and the second detection edge. The interface that charges is installed in the centre bore of mounting panel, and towards below. After the initial alignment, the high-precision alignment of the charging interface and the charging socket is realized through the directional movement of the end effector and the matching of the two pressure sensors and the two distance measuring sensors.

Description

Robot for automatic charging of unmanned aerial vehicle

Technical Field

The invention belongs to the field of charging robots, and particularly relates to an unmanned aerial vehicle automatic charging robot capable of accurately positioning and a driving method thereof.

Background

Nowadays, the number of mobile robots is increasing. They are used in different fields such as logistics, inventory, assembly of furniture, education, etc. However, the operation time of all mobile robots is limited, which limits the range of motion of the mobile robot. For indoor robots, this factor is not important, as the increased workspace can be compensated for by more docking stations. On the other hand, for an outdoor robot (such as a coal mine rescue robot) for exploring an unknown area, the operation time problem is very important.

There have been many studies on increasing the working range of a mobile robot. One of the most effective methods is to use renewable energy as a power source for the robot, such as solar energy. This makes the working range of mobile robots infinitely possible. However, it also has disadvantages such as sensitivity to external conditions and low charging speed. The most common way to increase the walking distance of a mobile robot is to increase the battery capacity. However, in this case, the size and weight of the mobile robot are also sharply increasing. Another approach may be taken from the aerospace industry. To increase the range of the aircraft, additional fuel tanks or fuel dispensers are required to be used to fill the aircraft. Based on the above, a new mobile charging robot is designed, which is simpler and cheaper than the original robot, can charge the main robot and increase the moving range of the main robot.

Disclosure of Invention

The invention aims to provide an unmanned aerial vehicle automatic charging robot with accurate positioning and a driving method thereof.

The invention relates to a robot for automatic charging of an unmanned aerial vehicle, which comprises an end effector and a position adjusting mechanism. The position adjusting mechanism can drive the end effector to move randomly in a horizontal plane and rotate around a vertical axis. The tail end executor comprises a mounting plate, a charging interface, a second pressure sensor and a distance measuring sensor. Two side edges forming an included angle of 90 degrees are arranged on the mounting plate; the two sides are respectively used as a first detection side and a second detection side. The two ends of the first detection edge are provided with second pressure sensors; and distance measuring sensors are arranged in the middle positions of the first detection edge and the second detection edge. The interface that charges is installed on the mounting panel, and is towards below. A square groove is formed in the top of the unmanned aerial vehicle capable of being in butt joint with the robot; the mounting plate can stretch into square groove.

This a charging process for automatic robot that charges of unmanned aerial vehicle is as follows:

step one, the charged unmanned aerial vehicle and the robot move relatively to a state that the square groove is located right below the end effector.

Secondly, the charged unmanned aerial vehicle moves upwards or the end effector moves downwards until the mounting plate abuts against the bottom surface of the square groove;

taking the orientation of a first detection edge on the moving block as a first target direction, and driving the end effector to move along the first target direction by the position adjusting mechanism; until one of the second pressure sensors detects a pressure value.

If the two second pressure sensors detect the pressure signals, the angle deviation does not exist in the charging interface.

If only one second pressure sensor detects a pressure signal, the charging interface has an angle deviation; calculating deviation angle

Wherein x is a distance value x measured by a distance measuring sensor on the first detection side; l denotes the side length of the mounting plate. The position adjusting mechanism drives the end effector to rotate around a vertical axis by a deviation angle alpha; the rotation direction is determined according to the position of the second pressure sensor which detects the signal; if the second pressure sensor close to the second detection edge detects the pressure signal, the rotation direction of the end effector is the direction in which the second detection edge is far away from the first detection edge. If the second pressure sensor far away from the second detection edge detects the pressure signal, the rotation direction of the end effector is the direction in which the second detection edge approaches the first detection edge.

Step four, the distance between the two distance measuring sensors and the side wall of the square groove is detected, and the position of the distance measuring sensors in the square groove and the relative position of the distance measuring sensors and the charging socket of the unmanned aerial vehicle are determined according to the two obtained distance values. According to the relative position, the position adjusting mechanism drives the end effector to move right above a charging socket of the charged unmanned aerial vehicle, and the butt joint of a charging interface on the end effector and the charging socket on the charged unmanned aerial vehicle is realized.

Preferably, at least three first pressure sensors are arranged at different positions on the bottom surface of the mounting plate.

Preferably, in the second step, the mounting plate is judged to be abutted against the bottom surface of the square groove by detecting the pressure signals by all the first pressure sensors.

Preferably, after the third step is performed once, the third step is performed again to ensure that the two second pressure sensors detect the pressure signals at the same time.

Preferably, the mounting plate is square; the first pressure sensors are four in number. Four first pressure sensors are respectively installed on four corners of the bottom surface of the square installation plate.

Preferably, the charging interface and the mounting plate form a vertical sliding pair. The charging interface slides up and down under the driving of the push-pull power assembly. The charging interface can be inserted into a charging socket at the top of the unmanned aerial vehicle below in a push-out state; in the retracted state of the charging interface, the bottom edge is higher than the bottom surface of the first pressure sensor.

Preferably, two groups of jacks staggered by 90 degrees along the circumferential direction are arranged on the charging socket; when the interface that charges is pegged graft with arbitrary a set of jack, the homoenergetic charges for unmanned aerial vehicle.

Preferably, the position adjusting mechanism comprises a plane driving module and a configuration ring. The plane driving module comprises a vertical rotating motor, a moving block, a frame and a Y-axis guide frame. The frame and the upper frame form a rotating pair with a common axis vertically arranged, and the rotating pair is driven to rotate by a vertical rotating motor. The Y-axis guide frame and the frame form a first sliding pair; the moving block and the Y-axis guide frame form a second sliding pair. The Y-axis guide frame is driven by a motor matched with a conveyor belt. The moving block is driven by matching a lead screw nut through a motor. The configuration ring is fixed on the moving block. The mounting plate is mounted below the configuration ring.

Preferably, the position adjustment mechanism further comprises a driving member. The driving member is disposed between the mounting plate and the disposition ring. Three driving motors are uniformly arranged on the edge of the configuration ring along the circumferential direction. The driving part comprises a driving motor, an upper rod piece and a lower rod piece. One end of each upper rod piece is rotationally connected with the configuration ring and is driven to rotate by the driving motor. The other ends of the three upper rod pieces and one ends of the three lower rod pieces form spherical pairs respectively; the other ends of the three lower rods and three different positions of the mounting plate on the end effector respectively form a revolute pair.

The invention has the following beneficial effects:

1. after the initial alignment, the high-precision alignment of the charging interface and the charging socket is realized through the directional movement of the end effector and the matching of the two pressure sensors and the two distance measuring sensors.

2. The present invention provides a reliable connection between robots by using encoders and pressure sensors. Angular, vertical, and horizontal deviations on the end effector may be estimated using pressure data on the interface.

3. The invention adopts the inverted driver, which is more compact than the traditional driver, so that the whole robot is smaller.

4. The mobile robot has strong adaptability and can be applied to various scenes.

Drawings

FIG. 1 is a schematic overall appearance of the present invention;

FIG. 2 is a perspective view of a planar drive module of the present invention;

FIG. 3 is a perspective view of a deployment ring of the present invention;

FIG. 4 is a schematic view of a drive member of the present invention;

FIG. 5 is a perspective view of an end effector of the present invention;

FIG. 6 is a bottom view of an end effector of the present invention;

fig. 7a-7d are schematic diagrams illustrating the alignment process of the charging interface and the charging dock according to the present invention.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1, 2 and 3, a robot for automatic charging of a drone includes a planar drive module 1, a configuration ring 2, a drive component 3 and an end effector 4. The plane driving module 1 comprises a vertical rotating motor 1-1, a moving block 1-2, a frame 1-3, two belts 1-4, three guide rods 1-5, a ball screw 1-6 and two Y-axis guide frames 1-7. The frame 1-3 and the upper machine frame form a rotating pair with a common axis arranged vertically. The vertical rotating motor 1-1 is arranged on the frame and is positioned right above the frame 1-3. An output shaft of the vertical rotating motor 1-1 is fixed with the frame 1-3 and is used for controlling the plane driving module 1 to rotate around a vertical axis. Two belts 1-4 are arranged on a plurality of belt wheels at two sides of the frame 1-3; the movement of the moving block 1-2 on the X axis is controlled in a belt transmission manner. Eight belt wheels are arranged on the frame 1-3 and are used for matching with the two belts 1-4. Two of the wheels are driving parts, and the remaining six wheels are driven parts. Two wheels of the driving part are connected by a guide rod 1-5 and controlled by a driving motor. The driving motor is arranged on the outer side of the driving wheel. The belt 1-4 is provided with a Y-axis guide frame 1-7 which is mutually fixed with the belt 1-4 and is also connected with the moving block 1-2. And a driving motor is arranged on one of the Y-axis guide frames 1-7. The moving block 1-2 is connected with the Y-axis guide frame 1-7 in a ball screw 1-6 mode, namely a belt 1-4 drives the Y-axis guide frame 1-7 to move transversely, and the moving block 1-2 is controlled to move in the X-axis direction. Meanwhile, a hole is formed above the moving block 1-2 and is connected with the guide rod 1-5 on the Y-axis guide frame 1-7 to ensure that the moving block 1-2 cannot deflect. Meanwhile, a hole is formed in the Y-axis guide frame 1-7 and is connected with the guide rod 1-5 on the frame 1-3, so that the Y-axis guide frame 1-7 is ensured not to deflect in the movement process.

The plane driving module 1 provided in this embodiment is only an example, and other existing plane driving modules 1 capable of realizing two-degree-of-freedom movement on a horizontal plane and rotating around a vertical axis can be used.

As shown in fig. 3, the configuration ring 2 is fixed on the bottom of the moving block 1-2; the plane drive module 1 controls the movement of the configuration ring 2 in the X-axis and the Y-axis and the rotation around the Z-axis. Three motor grooves are uniformly formed in the edge of the configuration ring 2 along the circumferential direction and are respectively used for fixedly mounting three driving motors.

The driving part 3 comprises a driving motor, an upper rod piece 3-1 and a lower rod piece 3-2. One ends of the three upper rod pieces 3-1 are respectively fixed with output shafts of the three driving motors. The other ends of the three upper rod pieces 3-1 are respectively connected with one ends of the three lower rod pieces 3-2 through ball hinges; the other ends of the three lower rods 3-2 and three positions which are uniformly distributed on the edge of the mounting plate 4-3 on the end effector 4 along the circumferential direction of the axis of the mounting plate respectively form a revolute pair.

As shown in fig. 5 and 6, the end effector 4 includes four first pressure sensors 4-1, two second pressure sensors 4-6, two distance measuring sensors 4-2, a mounting plate 4-3, a push-pull power assembly 4-4 and a charging interface 4-5.

The mounting plate 4-3 is square; four first pressure sensors 4-1 are respectively arranged on four corners of the bottom surface of the square mounting plate 4-3. Two adjacent side edges on the mounting plate 4-3 are respectively used as a first detection edge and a second detection edge. Two second pressure sensors 4-6 are respectively arranged at two ends of the first detection edge; two distance measuring sensors 4-2 are respectively arranged at the middle positions of the first detection edge and the second detection edge.

The charging interface 4-5 is arranged in the central hole of the mounting plate 4-3 and faces downwards. The charging interface 4-5 and the mounting plate 4-3 form a sliding pair in the vertical direction. The charging interface 4-5 slides up and down under the driving of the push-pull power assembly 4-4. The push-pull power assembly 4-4 adopts a cylinder. The air cylinder is connected with an air pump arranged on the mounting plate 4-3 through a reversing valve so as to control the pushing-out and retracting of the charging interface 4-5. The charging interface 4-5 can be inserted into a charging socket at the top of the unmanned aerial vehicle below in a pushed state; in the retracted state of the charging interface 4-5, the bottom edge is higher than the bottom surface of the first pressure sensor 4-1, thereby avoiding affecting the detection of the first pressure sensor 4-1.

The upper rod piece 3-1 and the lower rod piece 3-2 are respectively made of polylactic acid (PLA) materials and hollow aluminum tubes. The first pressure sensor 4-1 and the second pressure sensor 4-6 are both conductive rubber type pressure sensors, and conductive rubber is used as a sensitive element. When the contact contacts with the external object and is pressed, the conductive rubber is pressed, so that the resistance of the conductive rubber is changed, and the current flowing through the conductive rubber is changed. The charging interfaces 4-5 are made of hard aluminum, have higher strength and can bear the current of 18A.

The working range of the end effector 4 is 110mm on the positive and negative x-axis, 110mm on the positive and negative y-axis and 60mm on the positive and negative z-axis.

An encoder is arranged behind each driving motor rotating shaft, phase pulses of each rotation are directly sent to a PLC (programmable logic controller), the phase pulses are read through a high-speed measuring port of the PLC, the PLC can read the number of the pulses for a certain time in an interruption mode, and the number of the pulses in one minute can be calculated through simple multiplication and division operation, which is equivalent to the number of the rotations.

Each driving motor is powered by a power module; the power module consists of a battery and two DC-DC voltage regulators. The battery output voltage is 22.7-29.8 VDC. The drive motor requires 12VDC and the intel NUC requires 19 VDC. Dc-dc voltage regulators are used to achieve these voltages. The charging interface 4-5 in the end effector 4 is charged by a battery to transfer energy.

A square groove is formed in the top of the unmanned aerial vehicle matched with the charger robot; the depth of the square groove is larger than or equal to the thickness of the mounting plate 4-3. And a charging socket matched with the charging interface 4-5 is arranged at the center of the square groove. The side length of the square groove is 5 times of that of the mounting plate 4-3. Two groups of jacks staggered by 90 degrees along the circumferential direction are arranged on the charging socket; when charging interface and arbitrary a set of jack are pegged graft, the homoenergetic charges for unmanned aerial vehicle. Therefore, the charging interface has a correct charging posture every time the charging interface rotates by 90 degrees.

As shown in fig. 7a to 7d, the working process of the charger robot is as follows:

the method comprises the steps that firstly, a charger robot obtains a current unmanned aerial vehicle route and a current position of the unmanned aerial vehicle to be charged, and the robot is carried on a power system to automatically approach the unmanned aerial vehicle to be charged. The power system is an aircraft for carrying the charging robot to fly.

And step two, the power system carries the charging robot to hover above the charged unmanned aerial vehicle.

And step three, the current azimuth information is transmitted to the charger robot through the Bluetooth module by the electronic compass in the charged unmanned aerial vehicle, the charger robot compares the current azimuth information with the own azimuth information and adjusts the current azimuth information, and the vertical rotating motor 1-1 on the plane driving module 1 rotates forwards until the azimuth information of the plane driving module 1 is approximately aligned with the azimuth information of the charged unmanned aerial vehicle. At this time, the square groove on the unmanned aerial vehicle to be charged is located right below the end effector 4. Because the size of the square groove is larger than that of the end effector 4, the requirement on the alignment precision is low, and the unmanned aerial vehicle can fly under the guidance of a communication and positioning system; guidance may also be provided by machine vision.

Step four, three driving motors on the configuration ring 2 rotate forwards synchronously to drive the end effector 4 to descend, so that the bottom surface of the end effector 4 extends into the square groove of the charged unmanned aerial vehicle and abuts against the bottom surface of the square groove; when the first pressure sensors 4-1 are in contact with the bottom surface of the square groove of the charged unmanned aerial vehicle and sense current, the fact that the end effector 4 is attached to the charged unmanned aerial vehicle on the Z axis is shown, and the driving motor stops rotating. If the end effector 4 moves downwards to the limit position, the four first pressure sensors 4-1 do not sense all currents, the driving motor on the configuration ring 2 rotates reversely, the driving part 3 moves to enable the end effector 4 to ascend, and the charging robot moves to the position above the charged unmanned aerial vehicle again to align again.

Taking the orientation of the first detection edge on the moving block 1-2 as a first target direction (the direction U in fig. 7 a), the moving block 1-2 on the plane driving module 1 drives the end effector 4 to move along the first target direction until one of the second pressure sensors 4-6 detects a pressure value; at this time, one of the included angles is considered to abut against the side wall edge of the square groove.

If the two second pressure sensors 4-6 sense current, the coordinate axis of the plane driving module 1 of the charging robot is aligned with the coordinate axis of the unmanned aerial vehicle to be charged, and the posture of the charging interface is not required to be adjusted.

If only one second pressure sensor 4-6 senses current, it is indicated that an angle deviation exists between the charging interface and a charging socket on the unmanned aerial vehicle to be charged; the distance measuring sensor 4-2 positioned on the first detection edge detects the current distance value x; controllerCalculating deviation angle

Wherein l represents the side length of the mounting plate 4-3. A vertical rotating motor 1-1 on the plane driving module 1 drives an end effector to rotate by a deviation angle alpha, and the rotating direction is determined according to the position of a second pressure sensor 4-6 for detecting a signal; if the second pressure sensor 4-6 near the second detection edge contacts the side wall of the square groove, the end effector rotates in the forward direction (clockwise direction in fig. 7 c); the forward rotation is the rotation direction in which the second detection edge is far away from the first detection edge. If the second pressure sensor 4-6, which is far from the second detection edge, contacts the side wall of the square groove, the end effector rotates reversely (counterclockwise direction in fig. 7 c); the reverse rotation is the rotation direction of the second detection edge close to the first detection edge.

Step six, repeating the step five, and confirming that the two second pressure sensors 4-6 detect signals simultaneously; the posture of the charging interface is considered to be correct at this time.

And seventhly, the two distance measuring sensors detect the distance between the distance measuring sensors and the side wall of the square groove, and the position of the distance measuring sensors in the square groove is determined according to the two obtained distance values (because the length and the width of the square groove are consistent, the distance between the end effector and two adjacent side walls of the square groove can be obtained according to the distance values measured by the two distance measuring sensors, and then the position of the end effector in the square groove is determined), and the relative position between the distance measuring sensors and a charging socket of the unmanned aerial vehicle is determined. According to the relative position, the plane driving module 1 drives the end effector to move right above the charging socket of the charged unmanned aerial vehicle.

Step eight, the charging interface in the end effector stretches out, is in butt joint with a charging socket, and starts to charge the charged unmanned aerial vehicle.

Claims

1. The utility model provides a robot for unmanned aerial vehicle is automatic to be charged which characterized in that: comprises an end effector (4) and a position adjusting mechanism; the position adjusting mechanism can drive the end effector (4) to move randomly in a horizontal plane and rotate around a vertical axis; the end effector (4) comprises a mounting plate (4-3), a charging interface (4-5), a second pressure sensor (4-6) and a distance measuring sensor (4-2); two side edges forming an included angle of 90 degrees are arranged on the mounting plate (4-3); the two side edges are respectively used as a first detection edge and a second detection edge; two ends of the first detection edge are respectively provided with a second pressure sensor (4-6); distance measuring sensors (4-2) are arranged in the middle positions of the first detection edge and the second detection edge; the charging interface (4-5) is arranged on the mounting plate (4-3) and faces downwards; a square groove is formed in the top of the unmanned aerial vehicle capable of being in butt joint with the robot; the mounting plate (4-3) can extend into the square groove;

the method comprises the following steps that firstly, a charged unmanned aerial vehicle and a robot relatively move to a state that a square groove is located right below an end effector (4);

secondly, the charged unmanned aerial vehicle moves upwards or the end effector (4) moves downwards until the mounting plate (4-3) abuts against the bottom surface of the square groove;

taking the orientation of a first detection edge on the moving block (1-2) as a first target direction, and driving the end effector (4) to move along the first target direction by the position adjusting mechanism; until one of the second pressure sensors (4-6) detects a pressure value;

if the two second pressure sensors (4-6) detect pressure signals, the angle deviation does not exist in the charging interface;

if only one second pressure sensor (4-6) detects a pressure signal, an angle deviation exists in the charging interface; calculating deviation angle

Wherein x is a distance value x measured by a distance measuring sensor (4-2) on the first detection side; l represents the side length of the mounting plate (4-3); the position adjusting mechanism drives the end effector (4) to rotate around a vertical axis by a deviation angle alpha; the direction of rotation is determined according to the position of the second pressure sensor (4-6) which detects the signal; if the second pressure sensor (4-6) close to the second detection edge detects a pressure signal, the rotation direction of the end effector is such that the second detection edge is far away from the first detection edgeDetecting the direction of the edge; if the second pressure sensor (4-6) far away from the second detection edge detects the pressure signal, the rotation direction of the end effector is the direction that the second detection edge approaches the first detection edge;

step four, two distance measuring sensors detect the distance between the distance measuring sensors and the side wall of the square groove, and the position of the distance measuring sensors in the square groove and the relative position of the distance measuring sensors and a charging socket of the unmanned aerial vehicle are determined according to the two obtained distance values; according to the relative position, the position adjusting mechanism drives the end effector to move right above a charging socket of the charged unmanned aerial vehicle, and the butt joint of a charging interface on the end effector and the charging socket on the charged unmanned aerial vehicle is realized.

2. The robot of claim 1, wherein the robot is configured to automatically charge the unmanned aerial vehicle by: at least three first pressure sensors (4-1) are arranged at different positions of the bottom surface of the mounting plate (4-3).

3. The robot for unmanned aerial vehicle automatic charging of claim 2, characterized in that: in the second step, the fact that the mounting plate (4-3) is abutted against the bottom surface of the square groove is judged by detecting pressure signals through all the first pressure sensors (4-1).

4. The robot of claim 1, wherein the robot is configured to automatically charge the unmanned aerial vehicle by: after the third step is executed once, the third step is executed again to ensure that the two second pressure sensors (4-6) detect the pressure signals at the same time.

5. A robot for unmanned aerial vehicle automatic charging according to claim 2 or 3, characterized in that: the mounting plate (4-3) is square; the number of the first pressure sensors (4-1) is four; the four first pressure sensors (4-1) are respectively arranged at four corners of the bottom surface of the square mounting plate (4-3).

6. The robot of claim 1, wherein the robot is configured to automatically charge the unmanned aerial vehicle by: the charging interface (4-5) and the mounting plate (4-3) form a sliding pair in the vertical direction; the charging interface (4-5) slides up and down under the driving of the push-pull power assembly (4-4); the charging interface (4-5) can be inserted into a charging socket at the top of the unmanned aerial vehicle below in a push-out state; in the retracted state of the charging interface (4-5), the bottom edge is higher than the bottom surface of the first pressure sensor (4-1).

7. The robot of claim 1, wherein the robot is configured to automatically charge the unmanned aerial vehicle by: two groups of jacks staggered by 90 degrees along the circumferential direction are arranged on the charging socket; when the interface that charges is pegged graft with arbitrary a set of jack, the homoenergetic charges for unmanned aerial vehicle.

8. The robot of claim 1, wherein the robot is configured to automatically charge the unmanned aerial vehicle by: the position adjusting mechanism comprises a plane driving module (1) and a configuration ring (2); the plane driving module (1) comprises a vertical rotating motor (1-1), a moving block (1-2), a frame (1-3) and a Y-axis guide frame (1-7); the frame (1-3) and the upper frame form a rotating pair with a common axis arranged vertically, and the rotating pair is driven to rotate by a vertical rotating motor (1-1); the Y-axis guide frame (1-7) and the frame (1-3) form a first sliding pair; the moving block (1-2) and the Y-axis guide frame (1-7) form a second sliding pair; the Y-axis guide frames (1-7) are driven by a motor matched with a conveyor belt; the moving block (1-2) is driven by matching a motor with a lead screw nut; the configuration ring (2) is fixed on the moving block (1-2); the mounting plate (4-3) is mounted below the configuration ring (2).

9. The robot of claim 8, wherein the robot is configured to automatically charge the drone: the position adjusting mechanism also comprises a driving part (3); the driving component (3) is arranged between the mounting plate (4-3) and the configuration ring (2); three driving motors are uniformly arranged on the edge of the configuration ring (2) along the circumferential direction; the driving part (3) comprises a driving motor, an upper rod piece (3-1) and a lower rod piece (3-2); one end of each upper rod piece (3-1) is rotationally connected with the configuration ring (2) and is driven to rotate by a driving motor; the other ends of the three upper rod pieces (3-1) and one ends of the three lower rod pieces (3-2) respectively form a spherical pair; the other ends of the three lower rods (3-2) and three different positions of the mounting plate (4-3) on the end effector (4) respectively form a revolute pair.