Screwing manipulator and screwing robot

Abstract

The invention discloses a screwing manipulator and a screwing robot. The screwing robot comprises a screwing manipulator, a moving platform, a position and posture adjusting module and a control module, the position and posture adjusting module is fixedly assembled on the moving platform, the screwing manipulator is fixedly assembled on the position and posture adjusting module, the position and posture adjusting module is used for adjusting the posture of the screwing manipulator in a three-dimensional coordinate system, and the position and posture adjusting module is used for adjusting the posture of the screwing manipulator in the three-dimensional coordinate system. The control module is connected with the moving platform, the position and posture adjusting module and the screwing mechanical arm and at least used for adjusting the working states and working parameters of the moving platform, the position and posture adjusting module and the screwing mechanical arm. High torque is provided for the step fingers through the screwing driving mechanism with high torque output so as to drive the valve hand wheel to rotate, and active compensation is conducted on parasitic motion through force sensor information in combination with the pose adjusting module.

Description

Technical Field

[0001] The present invention particularly relates to a screwing manipulator and a screwing robot, belonging to the technical field of screwing robots. Background Art

[0002] In high-risk areas such as nuclear power plants and petrochemicals, valves are a key safety control component. They usually have a spoke-type handwheel, which is turned to open and close the valve. Some valves have large torque, and some valves need to turn the handwheel thousands of times before they can be closed. In the event of emergency safety situations such as leaks, the high-risk characteristics of the site make it difficult to manually close the valve. Therefore, the demand for automatic valve tightening manipulators and robots is increasing.

[0003] At present, most valve screwing robots use a light mechanical arm plus a multi-finger (more than three fingers) manipulator to insert into the gap of the valve handwheel and contact the spoke inside the valve to drive its rotation to open and close the valve. This design has the advantages of being small and flexible, but it also has some limitations. For example, when facing high-torque valves, the output torque at the end of the light mechanical arm is limited and cannot effectively open and close the valve. (High-torque actuators mean that the weight increases exponentially, and a larger mechanical arm and mobile chassis are required to carry its movement, which is not allowed in a narrow troubleshooting environment. Therefore, it is necessary to increase the output torque density instead of simply replacing the high-torque structure). Due to factors such as robot accuracy and environment, the manipulator will produce deviations and radial contact forces when docking with the handwheel. Excessive deviations and contact forces will lead to docking failures. In addition, the valve handwheel will produce axial parasitic motion during the screwing process. Excessive axial motion will damage the screwing device or cause the valve handwheel to lose contact with the manipulator.

[0004] Some devices use a passive compliant end manipulator to achieve compliant docking with the valve handwheel, and impedance control of the manipulator arm to achieve following the position of the valve handwheel and thus compensate for axial motion. They all have the problem of small passive compensation and uncontrollable compensation speed. For example, CN105082115A discloses a compliant adaptive valve screwing manipulator mechanism, in which the Hooke hinge mechanism of the screwing manipulator can only passively adjust the posture of the manipulator input end at a small angle when docking with the valve. The adjustable range is small, and the axial parasitic motion of the valve screwing can easily cause damage to the device. CN108000477A discloses a full-pose active and passive compliant robot and a method for screwing valves using the robot, which mainly relies on human visual operation and cannot be effectively positioned and operated in high-risk scenarios and when humans cannot intervene; the output torque of the end of the four-degree-of-freedom manipulator is limited, and it cannot effectively operate medium and large valves; its impedance control passively compensates for axial parasitic motion, and there are problems of small motion compensation and uncontrollable compensation speed. CN110667845A discloses a dual-arm operation flying robot system and method for valve screwing, but it can only manually connect the valve screwing device and the valve, lacks axial parasitic motion compensation, is easily stuck, and has poor applicability. Summary of the invention

[0005] The main purpose of the present invention is to provide a screwing manipulator and a screwing robot, so as to overcome the deficiencies in the prior art.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: A first aspect of an embodiment of the present invention provides a screwing robot, which comprises: a base, m stepped fingers, a linear drive mechanism and a screwing drive mechanism; The m step fingers are arranged on the base, and the m step fingers are configured to form a screwing fixing structure that can press against the screwing target in the radial direction of the screwing target. The step fingers and the base are movable in the radial direction of the base. The linear drive mechanism is in transmission cooperation with the m step fingers and is used to drive the step fingers to move in the radial direction of the base, so that the m step fingers gather or disperse; the screwing drive mechanism is rotationally cooperated with the base, and the screwing drive mechanism is used to drive the base and the m step fingers to rotate around the central axis of the base; Among them, the outer side surface of the step finger facing away from the central area of ​​the screwing fixing structure is an n-level step surface, and the n-level step surfaces are arranged in sequence along the axial direction of the base. The n-level step surfaces of the m step fingers are configured to form n supporting contour surfaces, and the radial dimensions of the n supporting contour surfaces are different, m≥2, n≥2.

[0007] Furthermore, the m step fingers are arranged at intervals on a circle, or the m step fingers are distributed radially from a central area of ​​a circle to all sides, and the center of the circle is located on the rotation axis of the base and the step fingers.

[0008] Furthermore, m guide structures are provided on the base, and each of the step fingers is movably matched with the base via a guide structure, and the guide structure is configured to enable the step fingers and the base to generate relative movement only in the radial direction of the base.

[0009] Furthermore, the guide structure is a guide groove extending radially along the base.

[0010] Furthermore, the guide groove is a T-shaped groove.

[0011] Furthermore, m locking mechanisms are provided on the base, each of which is matched with a step finger, and the locking mechanism has a locked state and an unlocked state. When the locking mechanism is in the locked state, the step finger and the base are fixed by the locking mechanism, and when the locking mechanism is in the unlocked state, the step finger and the base can move radially along the base.

[0012] Furthermore, n force monitoring components are arranged in the step finger, and the n force monitoring components correspond to the n-level step surfaces respectively. The force monitoring component is used to monitor the axial contact force information when the step surface where the force monitoring component is located contacts with the screwing target.

[0013] Furthermore, the screwing drive mechanism is a high-torque screwing drive mechanism.

[0014] Furthermore, the screwing drive mechanism includes a rotary motor, a planetary gear set and a rotary output shaft, the rotary motor is transmission-connected to the rotary output shaft via the planetary gear set, and the rotary output shaft is fixedly connected to the base.

[0015] A second aspect of an embodiment of the present invention provides a screwing robot, comprising: The screwing manipulator; And, a mobile platform, a posture adjustment module and a control module, the posture adjustment module is fixedly mounted on the mobile platform, the screwing robot is fixedly mounted on the posture adjustment module, the posture adjustment module is used to adjust the posture of the screwing robot in a three-dimensional coordinate system, the control module is connected to the mobile platform, the posture adjustment module, and the screwing robot, and is at least used to adjust the working state and working parameters of the mobile platform, the posture adjustment module, and the screwing robot.

[0016] Furthermore, the posture adjustment module includes a position adjustment module and a posture adjustment module, the position adjustment module is fixedly mounted on the mobile platform, the posture adjustment module is fixedly mounted on the position adjustment module, and the screwing robot is fixedly mounted on the posture adjustment module, the posture adjustment module is at least used to drive the screwing robot to rotate around the x-axis or y-axis of the three-dimensional coordinate system, and the position adjustment module is at least used to drive the posture adjustment module and the screwing robot to move along at least one of the x-axis, y-axis, and z-axis of the three-dimensional coordinate system.

[0017] Further, the position adjustment module includes a serial slider guide rail group and a mounting base, wherein the mounting base is mounted on the serial slider guide rail group and can move on the serial slider guide rail group along at least one of the x-axis, y-axis, and z-axis of the three-dimensional coordinate system; The posture adjustment module includes a fixed workbench, a rotating workbench and a posture adjustment drive mechanism. The fixed workbench is fixedly assembled on the mounting base. The rotating workbench rotates with the fixed workbench via a rotating shaft. The posture adjustment drive mechanism is fixedly arranged on the fixed workbench and is transmission-connected to the rotating shaft. The posture adjustment drive mechanism is used to drive the rotating workbench to rotate around the rotating shaft, and the axial direction of the rotating shaft is parallel to the x-axis or y-axis of the three-dimensional coordinate system.

[0018] Furthermore, the posture adjustment drive mechanism includes a rotary motor and a worm gear assembly, and the rotary motor is transmission-connected to the rotating shaft via the worm gear assembly.

[0019] Furthermore, the posture adjustment module also includes a visual module, which is used to obtain real-time posture information of the screwing target and transmit it to the control module. The control module adjusts the working state and working parameters of the mobile platform, the posture adjustment module, and the screwing robot according to the real-time posture information of the screwing target.

[0020] Furthermore, when the screwing robot performs a screwing action on a screwing target, the control module also adjusts the working parameters of the posture adjustment module according to the axial contact force when the screwing robot contacts the screwing target, so as to compensate for the axial motion of the screwing robot.

[0021] Compared with the prior art, the advantages of the present invention include: a screwing robot provided by an embodiment of the present invention has an omnidirectional four-wheel drive mobile platform, which can adapt to complex road conditions and perform rapid rough positioning. A screwing robot provided by an embodiment of the present invention adopts a high-torque valve screwing manipulator based on a two-way locking mechanism and a multi-cascade planetary gear to achieve a large torque and stable output of the valve, and a four-degree-of-freedom valve axial parasitic motion active compensation platform based on a gantry robot and a worm gear mechanism to perform high-response, large-stroke active compensation for different parasitic displacements of the valve. During the screwing process, when the pressure of the force sensor is detected to increase, the axial parasitic displacement is actively compensated by the three-degree-of-freedom gantry robot and the worm gear mechanism to ensure that the valve will not be stuck. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of a screwing robot provided in a typical implementation case of the present invention; Figure 2 It is a structural schematic diagram of a position adjustment module of a screwing robot provided in a typical implementation case of the present invention; Figure 3 It is a structural schematic diagram of a posture adjustment module of a screwing robot provided in a typical implementation case of the present invention; Figure 4 It is a schematic diagram of the internal structure of a posture adjustment module of a screwing robot provided in a typical implementation case of the present invention; Figure 5 It is a structural schematic diagram of a screwing manipulator of a screwing robot provided in a typical implementation case of the present invention; Figure 6 It is a structural schematic diagram of a single step finger of a screwing robot provided in a typical implementation case of the present invention; Figure 7 It is a structural schematic diagram of a high-torque screwing drive mechanism of a screwing robot provided in a typical implementation case of the present invention. DETAILED DESCRIPTION

[0023] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The following will further explain the technical solution, its implementation process and principle, etc. in conjunction with the accompanying drawings and specific implementation cases.

[0024] In a typical implementation, see Figure 1A screwing robot comprises: a mobile platform 1, a position adjustment module 2, a posture adjustment module 3, a vision module 4, a (pipe valve) screwing manipulator 5 and a control module, the screwing manipulator 5 is fixedly assembled on the posture adjustment module 3, the posture adjustment module 3 is fixedly assembled on the position adjustment module 2, the position adjustment module 2 is fixedly assembled on the mobile platform 1, the vision module 4 is assembled on the position adjustment module 2, and the mobile platform 1, the position adjustment module 2, the posture adjustment module 3, the screwing manipulator 5 and the vision module 4 are also connected to the control module.

[0025] Specifically, the screwing manipulator 5 can fix and release the screwing target (such as a pipeline valve, etc.) and perform screwing operations on the screwing target. Specifically, the posture adjustment module 3 is used to drive the screwing manipulator 5 to rotate around the x-axis or y-axis of a three-dimensional coordinate system to change the posture of the screwing manipulator 5 in the three-dimensional coordinate system, so that the screwing manipulator 5 and the screwing target maintain a specified relative posture, so that the screwing manipulator 5 can accurately dock with the screwing target. Specifically, the position adjustment module 2 is used to drive the posture adjustment module 3 and the screwing manipulator 5 to move along the x-axis, y-axis, and z-axis of the three-dimensional coordinate system to change the spatial position of the screwing manipulator 5 in the three-dimensional coordinate system so that the screwing manipulator 5 is aligned with the screwing target. Specifically, the visual module 4 is used to obtain the real-time posture information of the screwing target and transmit it to the control module. Specifically, the mobile platform 1 is used to drive the position adjustment module 2, the posture adjustment module 3, the visual module 4, and the screwing robot 5 to move as a whole in the workspace. The control module adjusts the working state and working parameters of the mobile platform 1, the posture adjustment module, and the screwing robot 5 according to the real-time posture information of the screwing target to achieve the alignment, fixation and screwing of the screwing robot 5 and the screwing target.

[0026] Specifically, the mobile platform 1 can adopt a structure known in the art. Exemplarily, the mobile platform 1 can include a frame, a power assembly, a transmission assembly, a walking assembly, a load platform, etc. The power assembly, the transmission assembly, the walking assembly, and the load platform are fixedly assembled on the frame, the power assembly is connected to the walking assembly through the transmission assembly, the position adjustment module 2 is fixedly assembled on the load platform, and the power assembly drives the walking assembly to move to achieve omnidirectional movement of the mobile platform 1. The walking assembly can be a crawler walking structure or a wheeled walking structure. The power assembly, the transmission assembly, the load platform, etc. are all known in the art, and their specific structures and the configuration structure / method between the functional components are not limited here.

[0027] Specifically, the position adjustment module 2 and the attitude adjustment module 3 are configured together to form a posture adjustment module, that is, a four-degree-of-freedom valve axial parasitic motion active compensation platform. For details, please refer to Figure 1 and Figure 2The position adjustment module 2 includes a serial slider guide group 202, a posture adjustment module mounting base 203, and a vision module mounting base 201. The serial slider guide group 202 includes an x-axis slider guide group, a y-axis slider guide group and a z-axis slider guide group. The guide rails of the x-axis slider guide group are fixedly assembled on the mobile platform 1, the y-axis slider guide group is assembled on the slider of the x-axis slider guide group, and the z-axis slider guide group is assembled on the slider of the y-axis slider guide group. The posture adjustment module mounting base 203 is fixedly assembled on the slider of the z-axis slider guide group, and the vision module mounting base 201 is fixedly assembled on the top of the guide rail of the z-axis slider guide group. The posture adjustment module 3 is fixedly assembled on the posture adjustment module mounting base 203, and the vision module 4 is fixedly assembled on the vision module mounting base 201. Through such a design, the posture adjustment module 3 and the screwing robot 5 as a whole can be translated along the x-axis, y-axis, and z-axis of the three-dimensional coordinate system.

[0028] Of course, the serial slider guide group 202 also includes a power source for driving the x-axis, y-axis, and z-axis translation and an auxiliary component for fixing its own slider at a specified position, which are all known in the art. In addition, in order to improve the structural strength of the serial slider guide group 202, reinforcing ribs 204 can be fixedly set between the z-axis slider guide group and the y-axis slider guide group. It should be noted that the serial slider guide group 202 can be a three-axis motion platform formed by configuration, or it can be part of a five-axis motion platform. The assembly structure between the components of the position adjustment module 2 itself and the assembly structure / method between the position adjustment module 2 and the posture adjustment module 3 and the visual module 4 can all be known in the art and are not particularly limited here.

[0029] For details, please refer to Figure 2 , Figure 3 and Figure 4The posture adjustment module 3 includes a fixed workbench 302, a rotating workbench 303 and a posture adjustment drive mechanism 301. The fixed workbench 302 is fixedly mounted on the posture adjustment module mounting base 203. The rotating workbench 303 is rotationally matched with the fixed workbench 302 via a rotating shaft. The posture adjustment drive mechanism 301 is fixedly arranged on the fixed workbench 302 and is transmission-connected with the rotating shaft. The posture adjustment drive mechanism 301 is used to drive the rotating workbench 303 to rotate with the rotating shaft as the axis. The axial direction of the rotating shaft is parallel to the x-axis or y-axis of the three-dimensional coordinate system. The screwing manipulator 5 is fixedly mounted on the rotating workbench 303 and rotates synchronously with the rotating workbench 303. More specifically, the posture adjustment drive mechanism 301 includes a rotating motor 301-1 and a worm gear assembly. The worm 301-2 of the worm gear assembly is fixedly connected to the output shaft of the rotating motor, and the worm wheel 301-3 of the worm gear assembly is fixedly connected to the rotating shaft. More specifically, the fixed workbench 302 may be a frame structure, and the rotating workbench 303 is disposed in a work space enclosed by the fixed workbench 302 .

[0030] For details, please refer to Figure 5 and Figure 6 The screwing manipulator includes a base 501, three (i.e., m=3) step fingers 503, a linear drive mechanism, and a screwing drive mechanism. The base 501 is fixedly assembled on the rotating worktable 303. The three step fingers 503 are arranged on the base 501. The three step fingers 503 are configured to form a screwing fixed structure that can press against the screwing target along the radial direction of the screwing target. The step fingers 503 and the base 501 are movable along the radial direction of the base 501. The linear drive mechanism is in transmission cooperation with the three step fingers 503 and is used to drive the step fingers 503 to move along the radial direction of the base 501, so that the three step fingers 503 are gathered or dispersed; the screwing drive mechanism is rotationally cooperated with the base 501, and the screwing drive mechanism is used to drive the base 501 and the three step fingers 503 to rotate around the central axis of the base 501.

[0031] Specifically, the three step fingers 503 are arranged at intervals on a circle, or the three step fingers 503 are radially distributed from the central area of ​​a circle to the surrounding areas, and the center of the circle is located on the rotation axis of the base 501 and the step fingers 503. More specifically, three guide structures are arranged on the base 501, and the length direction of each guide structure extends along the radial direction of the base 501. Each step finger 503 is movably matched with the base 501 through a guide structure, and the guide structure is configured to enable the step finger 503 and the base 501 to only generate relative movement in the radial direction of the base 501. Exemplarily, the guide structure is a guide groove extending along the radial direction of the base 501, and the guide groove is preferably a T-shaped groove. A part of each step finger 503 is embedded in a guide groove and movably matched with the base 501, thereby realizing unidirectional movement of the step finger 503 and the base 501.

[0032] Specifically, three locking mechanisms 502 are further arranged on the base 501, each of the locking mechanisms 502 matches with a step finger 503, and the locking mechanisms 502 have a locked state and an unlocked state. When the locking mechanism 502 is in the locked state, the step finger 503 and the base 501 are fixed by the locking mechanism 502, and when the locking mechanism 502 is in the unlocked state, the step finger 503 and the base 501 can generate relative movement along the radial direction of the base 501. Specifically, each locking structure 502 includes two locking blocks and a locking drive mechanism, the two locking blocks are respectively arranged on both sides of the guide groove and are in transmission connection with the locking drive mechanism, and the two locking blocks can move toward or away from each other along the driving line of the locking drive mechanism in a direction perpendicular to the length direction of the guide groove, thereby switching between the locked state and the unlocked state.

[0033] Specifically, the outer side surface of the step finger 503 facing away from the central area of ​​the screwing fixing structure is a three-level (i.e., n=3) step surface, and the three-level step surfaces are arranged in sequence along the axial direction of the base 501. The three-level step surfaces of the three step fingers are configured to form three supporting contour surfaces, and the radial dimensions of the three supporting contour surfaces are different, so that they can adapt to screwing targets of different sizes.

[0034] Specifically, three force monitoring components 507 / 508 / 509 are also arranged in the step finger 503, and the three force monitoring components 507 / 508 / 509 correspond to the three-level step surfaces respectively. The force monitoring components 507 / 508 / 509 are used to monitor the axial contact force information (such as the magnitude and / or vector direction of the axial contact force) when the step surface where the force monitoring component is located contacts the screwing target, and transmit the monitored axial contact force information and other information to the control module, and the control module adjusts the working state and working parameters of the position adjustment module 2 and the posture adjustment module 3 according to the axial contact force information to realize the axial motion compensation of the screwing manipulator. Specifically, the force monitoring component can be a force sensor, etc.

[0035] For details, please refer to Figure 7 , the screwing drive mechanism is a high torque screwing drive mechanism. Specifically, the screwing drive mechanism includes a rotary motor 504, a planetary gear set 505 and a rotary output shaft 506, the rotary motor 504 is connected to the rotary output shaft 506 via the planetary gear set 505, and the rotary output shaft 506 is fixedly connected to the base 501. Specifically, the planetary gear set 505 is a multi-stage planetary gear, and can achieve high torque output.

[0036] It should be noted that the motor, force sensor, control module, and numerical control program relied upon by the control module involved in the embodiments of the present invention are all known in the art and are not specifically limited here.

[0037] In a more specific implementation scheme, the working process of the screwing robot to screw a valve (i.e., the valve is used as the screwing target) is mainly divided into three stages, specifically including: The first stage is the precise docking of the screwing robot 5 and the valve: First, the screwing robot quickly reaches the front of the valve through the omnidirectional four-wheel drive mobile platform 1 for rough positioning; secondly, the visual module 4 obtains the specific posture information of the valve and transmits it to the control module of the robot; finally, the screwing robot performs precise positioning according to the posture information of the valve transmitted by the visual module 4, specifically, the posture of the screwing manipulator 5 is adjusted by the joint synchronous movement of the position adjustment module 2 and the posture adjustment module 3 to accurately dock the valve (m stepped fingers 503 extend into the gap between the spokes of the handwheel of the valve).

[0038] The second stage is the stage of screwing the manipulator to screw the valve: First, each step finger 503 moves radially from the center to the outside synchronously, and presses against the outer ring of the handwheel through the step surface, and at the same time the locking mechanism 502 locks the step finger 503; then, the high-torque screwing drive mechanism (motor and multi-stage planetary gear) works, thereby driving the step finger 502 to rotate together with the base 501 to perform high-torque stable screwing of the valve handwheel.

[0039] The third stage is the stage where the screwing robot actively compensates for the axial parasitic motion of the valve: First, the valve tightening process will produce axial parasitic motion, which will generate axial force on the step surface of the step finger 503 in close contact with the handwheel or cause the handwheel to gradually separate from the step surface; secondly, the force sensor installed behind the step finger 503 obtains the axial force information of the contact between the step finger 503 and the handwheel and transmits it to the control module; finally, the control module responds quickly according to the axial force information transmitted by the force sensor and actively compensates for the large-stroke motion of the tightening process through the position adjustment module (serial slider guide group) and the posture adjustment module to complete the valve tightening operation.

[0040] Compared with the passive compensation based on the compliant mechanism, the active motion compensation adopted by the present invention has a fast response and a large compensation amplitude. The existing method of operating by carrying a screwing device with a six-degree-of-freedom mechanical arm has a certain flexibility, but the load at the end of the high-degree-of-freedom mechanical arm is limited, and it is difficult for the carried actuator to open large and medium-sized rotary valves; and the high degree of freedom increases the control difficulty. For this reason, the present invention adopts a three-degree-of-freedom gantry (i.e., a series slider guide group 202) robot to realize large-space movement, and adopts a worm gear mechanism to drive the rotating worktable to rotate to adjust the angle, so that the portable end load is greatly increased. In addition, due to the decoupling of the three-degree-of-freedom motion of the gantry robot, in the process of active compensation, there is no need to perform forward and inverse kinematics solutions of the target position, so as to achieve faster and more stable parasitic displacement compensation.

[0041] The present invention provides a high-torque screwing robot with wide applicability, high precision and strong autonomy, which is used to autonomously screw valves in high-risk environments where humans cannot intervene. Compared with the prior art, the screwing robot provided by an embodiment of the present invention has the advantages of fully automatic real-time precise adjustment of posture, large stroke and high-response active compensation of parasitic motion, and high torque output.

[0042] A screwing robot provided in an embodiment of the present invention can be used as a special robot for emergency rescue and disposal of pipeline valves. The screwing robot provided in an embodiment of the present invention can realize fully automatic operation, and based on modular design, multi-modal information combined with a multi-degree-of-freedom motion device, the manipulator can realize precise docking between the manipulator and the valve, and high-response and large-stroke active motion compensation for different parasitic motions of the valve. The high-torque manipulator can realize stable output of large torque to the valve, and can replace manual high-risk operations in emergency safety situations such as leakage in high-risk fields such as nuclear power plants and petrochemicals.

[0043] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A screwing robot, characterized in that: include: A base, m step fingers, a linear drive mechanism and a screw drive mechanism; The m step fingers are arranged on the base, and the m step fingers are configured to form a screwing fixing structure that can press against the screwing target in the radial direction of the screwing target. The step fingers and the base are movable in the radial direction of the base. The linear drive mechanism is in transmission cooperation with the m step fingers and is used to drive the step fingers to move in the radial direction of the base, so that the m step fingers gather or disperse; the screwing drive mechanism is rotationally cooperated with the base, and the screwing drive mechanism is used to drive the base and the m step fingers to rotate around the central axis of the base; Among them, the outer side surface of the step finger facing away from the central area of ​​the screwing fixing structure is an n-level step surface, and the n-level step surfaces are arranged in sequence along the axial direction of the base. The n-level step surfaces of the m step fingers are configured to form n supporting contour surfaces, and the radial dimensions of the n supporting contour surfaces are different, m≥2, n≥2.

2. The screwing robot according to claim 1, characterized in that: The m step fingers are arranged at intervals on a circle, or the m step fingers are radially distributed from a central area of ​​a circle to the surrounding areas, and the center of the circle is located on the rotation axis of the base and the step fingers.

3. The screwing robot according to claim 1 or 2, characterized in that: The base is provided with m guide structures, each of the step fingers is movably matched with the base via one of the guide structures, and the guide structures are configured to enable the step fingers and the base to generate relative movement only in the radial direction of the base; Preferably, the guide structure is a guide groove extending radially along the base; Preferably, the guide groove is a T-shaped groove.

4. The screwing robot according to claim 1 or 2, characterized in that: The base is also provided with m locking mechanisms, each of which is matched with a step finger, and the locking mechanism has a locked state and an unlocked state. When the locking mechanism is in the locked state, the step finger and the base are fixed by the locking mechanism, and when the locking mechanism is in the unlocked state, the step finger and the base can move radially along the base.

5. The screwing robot according to claim 1, characterized in that: The step finger is also provided with n force monitoring components, the n force monitoring components correspond one-to-one to the n-level step surfaces respectively, and the force monitoring component is used to monitor the axial contact force information when the step surface where the force monitoring component is located contacts with the screwing target.

6. The screwing robot according to claim 1, characterized in that: The screwing drive mechanism is a high-torque screwing drive mechanism; Preferably, the screwing drive mechanism includes a rotary motor, a planetary gear set and a rotary output shaft, the rotary motor is transmission-connected to the rotary output shaft via the planetary gear set, and the rotary output shaft is fixedly connected to the base.

7. A screwing robot, characterized in that: include: The screwing robot according to any one of claims 1 to 6; And, a mobile platform, a posture adjustment module and a control module, the posture adjustment module is fixedly mounted on the mobile platform, the screwing robot is fixedly mounted on the posture adjustment module, the posture adjustment module is used to adjust the posture of the screwing robot in a three-dimensional coordinate system, the control module is connected to the mobile platform, the posture adjustment module, and the screwing robot, and is at least used to adjust the working state and working parameters of the mobile platform, the posture adjustment module, and the screwing robot.

8. The screwing robot according to claim 7, characterized in that: The posture adjustment module includes a position adjustment module and a posture adjustment module, the position adjustment module is fixedly mounted on the mobile platform, the posture adjustment module is fixedly mounted on the position adjustment module, and the screwing robot is fixedly mounted on the posture adjustment module, the posture adjustment module is at least used to drive the screwing robot to rotate around the x-axis or y-axis of the three-dimensional coordinate system, and the position adjustment module is at least used to drive the posture adjustment module and the screwing robot to move along at least one of the x-axis, y-axis, and z-axis of the three-dimensional coordinate system.

9. The screwing robot according to claim 8, characterized in that: The position adjustment module comprises a serial slider guide rail set and a mounting base, wherein the mounting base is mounted on the serial slider guide rail set and can move on the serial slider guide rail set along at least one of the x-axis, y-axis, and z-axis of the three-dimensional coordinate system; The posture adjustment module comprises a fixed workbench, a rotating workbench and a posture adjustment driving mechanism, wherein the fixed workbench is fixedly mounted on the mounting base, the rotating workbench is rotationally matched with the fixed workbench via a rotating shaft, the posture adjustment driving mechanism is fixedly arranged on the fixed workbench and is transmission-connected with the rotating shaft, and the posture adjustment driving mechanism is used to drive the rotating workbench to rotate with the rotating shaft as the axis, and the axial direction of the rotating shaft is parallel to the x-axis or y-axis of the three-dimensional coordinate system; Preferably, the posture adjustment drive mechanism comprises a rotary motor and a worm gear assembly, and the rotary motor is transmission-connected to the rotating shaft via the worm gear assembly.

10. The screwing robot according to claim 8 or 9, characterized in that: The posture adjustment module also includes a visual module, which is used to obtain real-time posture information of the screwing target and transmit it to the control module, and the control module adjusts the working state and working parameters of the mobile platform, the posture adjustment module, and the screwing manipulator according to the real-time posture information of the screwing target; And / or, during the process of the screwing robot performing a screwing action on the screwing target, the control module also adjusts the working parameters of the posture adjustment module according to the axial contact force when the screwing robot contacts the screwing target to compensate for the axial motion of the screwing robot.

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