A space robot arm end grasping mechanism and grasping method

Abstract

The present invention discloses a space manipulator end grasping mechanism and grasping method, which belongs to the field of space detection technology. The space manipulator end grasping mechanism includes a shell component, a capture component constrained inside the shell component, a locking component and a dragging component fixedly connected to the shell component, and can realize large tolerance flexible grasping of a target adapter on a space cooperation target through capture, dragging and locking operations.

Description

Technical Field

[0001] The present invention belongs to the technical field of space exploration, is applied to a space station manipulator, and particularly relates to a grasping mechanism at the end of a space manipulator. Background Art

[0002] The end-grasping mechanism is installed at the shoulder and wrist of the space manipulator, which can grasp fixed and floating space cooperation targets, realize the manipulator's on-orbit crawling, support astronauts' extravehicular activities, and other tasks. The manipulator end effectors that have been successfully launched and applied include the International Space Station Canadian Manipulator System (SSRMS) end effector and the International Space Station European Arm ERA end effector. Among them, the Canadian manipulator failed to crawl, and the European Arm ERA end effector could not grasp floating targets.

[0003] The patent (CN105659728B) discloses a rope capture end effector, which realizes the large tolerance capture of a target object with a specific docking interface, but the end effector cannot lock the target object with a large pre-tightening force and make an electrical connection. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, a novel end-gripping mechanism and a gripping method are designed, which can achieve large tolerance, high precision and high rigidity gripping of a target adapter through capturing, dragging and locking operations.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A space manipulator end grasping mechanism, used for grasping and releasing a target adapter on a space cooperation target, characterized in that the space manipulator end grasping mechanism comprises a housing component, a capture component, a locking component and a dragging component;

[0007] The housing assembly has a structure coupled to the target adapter to constrain the capture assembly via a guide rail;

[0008] The capture component is used to implement initial capture of the target adapter;

[0009] The drag component is used to drag the capture component and the target adapter after the capture is completed, so as to achieve the docking between the shell component and the target adapter; the drag component is fixed on the shell component, and the drag component includes a drag ball screw, a drag drive component, a bottom cover, and a transmission gear; the drag ball screw and the drag drive component are fixed on the bottom cover; one end of the drag ball screw is connected to the output end of the drag drive component through the transmission gear, and the other end of the drag ball screw is connected to the capture component, and the dragging of the capture component and the target adapter is achieved by dragging the ball screw to make a linear motion along the axial direction;

[0010] The locking assembly is fixed on the housing assembly and is used to lock the target adapter and realize electrical connection with the target adapter.

[0011] Preferably, the locking assembly includes at least 4 sets of locking mechanisms, follower assemblies, locking drive assemblies and large gears; the locking mechanism, locking drive assembly and large gear are fixed on the outer surface of the housing, the locking drive mechanism is connected to the large gear through gear meshing, and the large gear is connected to all locking mechanisms through gear meshing; the follower assembly fixes the cable for electrical connection, and the follower assembly is fixed on the locking mechanism.

[0012] Preferably, the locking mechanism includes a roller, an electrical connector, a connecting rod, a locking support frame, a movable component, a disc spring component, a small guide rail, a fixed bracket, and a locking ball screw; when locked, the roller is connected to the target adapter, and the electrical connector is electrically connected to the target adapter;

[0013] The roller is connected to the connecting rod through a pin, the connecting rod is connected to the movable assembly through a pin, and the disc spring assembly is fixed to the movable assembly;

[0014] The small guide rail is fixed to the housing assembly and connected to the locking support frame through an adapter;

[0015] The fixing bracket and the bearing support are fixed on the housing assembly;

[0016] The electrical connector and the follower assembly are fixed on the locking support frame;

[0017] A gear is designed on the locking ball screw nut and is fixed on the bearing support. After the locking ball screw passes through the fixed bracket and the movable component, it is fixedly connected to the locking support bracket.

[0018] Preferably, the capture assembly includes a fixed ring, a wire rope assembly, a rotating ring, a one-dimensional force sensor, a slider assembly and a capture drive assembly; the fixed ring and the rotating ring are connected by a bearing; the two ends of the wire rope assembly are respectively connected to the fixed ring and the rotating ring, and there are at least three sets of wire rope assemblies, which are evenly distributed along the circumference of the fixed ring and the rotating ring; the capture drive assembly is fixed on the fixed ring, and the output end is connected to the rotating ring through a gear; at least three groups of slider assemblies are fixed on the fixed ring, evenly distributed along the axial direction of the fixed ring, and connected to the guide rail; the one-dimensional force sensor is fixed on the slider assembly; when the capture assembly is working, the capture drive assembly drives the rotating ring to rotate, driving one end of the wire rope assembly to move, so that the initial circle formed by the wire rope assembly shrinks, and the target adapter is captured.

[0019] Preferably, the capture component further comprises two in-position switches, which are fixedly connected to the fixing ring and are used to indicate two position states of the capture component, namely, a capture start position and a capture end position.

[0020] Preferably, a power supply module is installed on the bottom cover of the dragging assembly for power distribution control of the entire robotic arm.

[0021] Preferably, it also includes a controller installed on the outside of the shell assembly, which is used to control the capture drive assembly, the drag drive assembly, the locking drive assembly, and communicate with the robot arm.

[0022] Preferably, a six-dimensional force sensor is also included, which is connected to the bottom cover and is used to measure the force during the grasping process.

[0023] Preferably, it also includes a quick-change device connected to the six-dimensional force sensor for realizing on-track replacement of the combination of the shell component, the capture component, the locking component and the dragging component.

[0024] A grasping method for a grasping mechanism at the end of a space manipulator, which sequentially captures, drags, and locks a target adapter:

[0025] Capture operation: The capture drive assembly drives the rotating ring to rotate, driving one end of the wire rope assembly to move, so that the initial circle formed by the three sets of wire rope assemblies shrinks until the target adapter is captured;

[0026] Dragging operation: The dragging driving component drives the dragging ball screw to rotate through the transmission gear, and the screw nut makes a linear motion along the axial direction, dragging the capture component and the target adapter to move; during the dragging process, the housing component is coupled with the target adapter to position the end gripping mechanism and the target adapter, so as to achieve docking between the end gripping mechanism and the target adapter;

[0027] Locking operation: The locking drive assembly drives the locking ball screw nut of the locking mechanism to rotate through the large gear, and the screw together with the locking support frame and the movable assembly moves linearly along the small guide rail to achieve locking and electrical connection of the target adapter.

[0028] Preferably, the capture, dragging and locking operations are controlled by a controller.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1) The end gripping mechanism adopts the structural design of the capture component. During the capture process, the capture rod is driven to move to the initial dragging position by winding the wire rope component, eliminating the radial error between the target adapter and the end gripping mechanism, realizing large tolerance flexible gripping, and the capture position tolerance is better than 100mm.

[0031] 2) The end gripping mechanism adopts the structural design of the dragging component. During the dragging process, the posture error between the target adapter and the end gripping mechanism is eliminated through coarse positioning and fine positioning operations, achieving high-precision docking with a docking accuracy better than 0.1mm.

[0032] 3) The end gripping mechanism adopts the structural design of the locking assembly. During the locking process, the locking drive assembly drives the large gear to rotate, and the large gear synchronously drives all locking mechanisms to lock the target adapter with a large preload force. The locking stiffness is better than 2e7Nm / rad.

[0033] 4) The capture, dragging and locking actions of the end grasping mechanism are connected in sequence. While realizing each step of the action, it provides the initial motion conditions for the next step of the action, so that the combination of the capture component, the dragging component and the locking component is integrated into an organic whole, and the large-tolerance capture, high-precision docking and high-rigidity locking of the target adapter are realized step by step, and the target adapter can be repeatedly grasped in a space environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0035] Figure 1 Schematic diagram of a novel end-gripping mechanism provided by an embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of the composition of a target adapter provided by an embodiment of the present invention;

[0037] Figure 3 is a schematic diagram of the composition of a capture component provided by an embodiment of the present invention;

[0038] Figure 4 It is a schematic diagram of the composition of the drag component provided by an embodiment of the present invention;

[0039] FIG. 5( a ) is a schematic diagram of the locking assembly provided in an embodiment of the present invention. Figure 1 ;

[0040] FIG. 5( b ) is a schematic diagram of the locking assembly provided in an embodiment of the present invention. Figure 2 ;

[0041] FIG. 5( c ) is a schematic diagram of the locking assembly provided in an embodiment of the present invention. Figure 3 ;

[0042] Figure 6 It is a schematic diagram of the composition of the housing assembly provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] The present invention provides a novel end-grabbing mechanism for grabbing and releasing a target adapter on a space cooperation target. The target adapter has a structure coupled with the end-grabbing structure. Figure 2 It is a typical structure of a target adapter, including a capture rod 37, a cam 38, a docking gear plate 39, a claw 40 and a floating electrical connector 41.

[0045] End gripping mechanism, such as Figure 1 As shown, it includes a capture component 1, a locking component 2, a controller 3, a shell component 4, a drag component 5, a six-dimensional force sensor 6 and a quick-change device 7. In this embodiment, the capture component 1 is constrained inside the shell component 4 by three guide rails 36, and the one-dimensional force sensor 11 installed at the end is connected to the drag ball screw nut 15 of the drag component 5. The drag component 5 is connected to the shell component 4 by screws. The locking component 2 is provided with four sets of locking mechanisms, which are distributed around the shell component 4, and are connected to the shell component 4 by a fixed bracket 29, a bearing support frame 31 and a small guide rail 28. The locking drive component 32 is fixed to the shell component 4 by screws. The composition of the shell component is shown in the figure Figure 6 As shown, it includes a guide rail 36, an end toothed disc 35 and a housing 34, and the end toothed disc 35 is coupled with a cam 38 and a docking toothed disc 39.

[0046] The capture assembly 1 is used for initial capture of the target adapter, and the capture assembly 1 can be constrained inside the housing assembly 4 by three guide rails 36 . Figure 3The figure is a schematic diagram of the capture assembly 1, which includes a fixed ring 8, an in-position switch 9, a slider assembly 10, a one-dimensional force sensor 11, a wire rope assembly 12, a rotating ring 13 and a capture drive assembly 14. The fixed ring 8 and the rotating ring 13 are connected by a thin-walled bearing. Two in-position switches 9 are fixed to the fixed ring 8 by screws to indicate the capture start position and the capture end position; one end of the wire rope assembly 12 is connected to the fixed ring and the other end is connected to the rotating ring. There are three sets in total, which are evenly distributed along the circumference of the fixed ring 8 and the rotating ring 13 at 120 degrees. The capture drive assembly 14 is fixed to the fixed ring 8, and the output end is connected to the rotating ring 13 through a gear. The slider assembly 10 is fixed to the fixed ring 8, and there are three sets in total, which are evenly distributed along the circumference of the fixed ring 8 at 120 degrees, and are connected to the guide rail 36. The slider assembly corresponds to the guide rail one by one. The one-dimensional force sensor 11 is fixed to the slider assembly 10. When the capture assembly is working, the capture drive assembly 14 drives the rotating ring 13 to rotate, driving one end of the wire assembly 12 to move, so that the initial circle formed by the three sets of wire rope assemblies 12 shrinks until the capture rod is captured. The entire capture process can achieve a capture position tolerance better than 100mm and a posture tolerance better than 15°.

[0047] Figure 4 The figure is a schematic diagram of the drag assembly 5. The drag assembly 5 is fixed on the bottom surface of the housing, and includes a drag ball screw 15, a power supply module 16, a drag drive assembly 17, a bottom cover 18 and a transmission gear 19. The drag ball screw 15 is fixed on the central axis of the bottom cover 18 through a pair of bearings, and one end is connected to the transmission gear 19, and the other end is connected to the one-dimensional force sensor 11 at the end of the capture assembly 1. The drag drive assembly 17 is fixed on the bottom cover 18, and the output end is connected to the drag ball screw 15 through the transmission gear 19. The power supply module 16 is fixed to the bottom cover 18 by screws. When the drag assembly 5 is working, the drag drive assembly 17 drives the drag ball screw 15 to rotate through the transmission gear 19, and the nut of the drag ball screw 15 moves linearly along the axial direction, and the drag target adapter is docked with the end gripping mechanism to eliminate the posture error between the two. During the dragging process, the end gear disc 35 cooperates with the cam 38 and the docking gear disc 39 in sequence to achieve the rough positioning and fine positioning between the end gripping mechanism and the target adapter, respectively, and achieve high-precision docking between the two, with a docking accuracy better than 0.1mm. The power supply module 16 installed on the bottom cover is used for the power distribution control of the entire arm of the robot.

[0048] Figure 5 (a), (b), (c) are schematic diagrams of the locking assembly, which includes a locking mechanism 20, a follower assembly 21, a locking drive assembly 32 and a large gear 33. Four sets of locking mechanisms 20, locking drive assemblies 32 and large gears 33 are fixed to the outer surface of the housing, the locking drive mechanism 32 is connected to the large gear 33 through gear meshing, and the large gear 33 is connected to the four sets of locking mechanisms 20 through gear meshing. The follower assembly 21 is used to fix the cable for electrical connection, the number of follower assemblies 21 is the same as the number of locking mechanisms 20, and each follower assembly is fixed to a locking mechanism.

[0049] The locking mechanism 20 includes a roller 22, an electrical connector 23, a connecting rod 24, a locking support frame 25, a movable assembly 26, a disc spring assembly 27, a small guide rail 28, a fixed bracket 29, a locking ball screw 30, and a bearing support 31. The roller 22 is connected to the connecting rod 24 through a pin, the connecting rod 24 is connected to the movable assembly 26 through a pin, the disc spring assembly 27 is fixed to the movable assembly 26 through a screw, the small guide rail 28 is fixed to the housing assembly 4, and is connected to the locking support frame 25 through an adapter. The fixed bracket 29 and the bearing support 31 are fixed to the housing assembly 4 through screws, the locking ball screw 30 is designed with a gear on the nut, and is fixed to the bearing support 31 through a pair of angular contact bearings, and the screw passes through the fixed bracket 29 and the movable assembly 26, and is fixed to the locking support frame 25; the electrical connector 23 and the follower assembly 21 are fixed to the locking support frame 25, and the follower assembly 21 is used to fix the cable connected to the electrical connector 23. When the locking assembly is working, the locking drive assembly 32 simultaneously drives the locking ball screws 30 nuts of the four locking mechanisms 20 to rotate through the large gear 33, and the locking ball screws 30 together with the locking support frame 25 and the movable assembly 26 make a linear motion along the small guide rail 28, and the follower assembly 21 makes a straight line along the axial direction, the moving roller 22 is connected to the claw 40, and the electrical connector 23 is connected to the floating electrical connector 41 of the target adapter, so as to realize the large pre-tightening force locking of the target adapter claw 40 and the connection of the electrical connector, and the locking stiffness is better than 2e7Nm / rad.

[0050] The controller 3 is used for the functions of gripping control of the entire end gripping mechanism, self-temperature control, and communication with the robot arm.

[0051] The six-dimensional force sensor 6 is installed at the tail of the end and connected to the drag component 5 to measure the force conditions of the end grasping mechanism during the grasping process.

[0052] The quick-change device 7 is connected to the six-dimensional force sensor to achieve quick on-track replacement.

[0053] The present invention provides a method for grasping the end of a space robot arm, which uses a controller to sequentially perform the three operation steps of capturing, dragging, and locking:

[0054] Capture operation: the capture drive assembly 14 drives the rotating ring 13 to rotate, driving one end of the wire rope assembly 12 to move, so that the initial circle formed by the three sets of wire rope assemblies 12 shrinks until the capture rod 37 on the target adapter of the space cooperation target is captured;

[0055] Dragging operation: The dragging driving assembly 17 drives the dragging ball screw 15 to rotate through the transmission gear 19, and the screw nut makes a linear motion along the axial direction, dragging the capture assembly 1 and the target adapter to move. During the dragging process, the end gear plate 35 cooperates with the cam 38 and the docking gear plate 39 in sequence to perform rough positioning and fine positioning between the end gripping mechanism and the target adapter, respectively, to achieve docking between the end gripping mechanism and the target adapter;

[0056] Locking operation: The locking drive assembly 32 simultaneously drives the locking ball screws 30 nuts of the four locking mechanisms 20 to rotate through the large gear 33. The screws together with the locking support frame 25 and the movable assembly 26 move linearly along the small guide rail 28 to achieve the locking of the claws 40 on the target adapter and the connection of the electrical connector.

[0057] The release process is the reverse process of the grab, that is, first lock and release, then drag and release, and finally capture and release to achieve the release of the target adapter.

[0058] After the release process is completed, the end gripping mechanism returns to its initial state. When gripping again, the above method is used to sequentially perform the three operation steps of capturing, dragging and locking to achieve the target adapter to be gripped again; when releasing, the three operation steps of locking release, dragging release and capturing release are sequentially performed to achieve the target adapter to be released again. Repeating the above steps can achieve repeated gripping of the target adapter.

[0059] The embodiments described above are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A space manipulator end grasping mechanism for grasping and releasing a target adapter on a space cooperation target, characterized in that: The space robot arm end grasping mechanism comprises a housing component, a capture component, a locking component and a dragging component; The housing assembly has a structure coupled to the target adapter to constrain the capture assembly via a guide rail; The capture component is used to implement initial capture of the target adapter; The drag component is used to drag the capture component and the target adapter after the capture is completed, so as to achieve the docking between the shell component and the target adapter; the drag component is fixed on the shell component, and the drag component includes a drag ball screw, a drag drive component, a bottom cover, and a transmission gear; the drag ball screw and the drag drive component are fixed on the bottom cover; one end of the drag ball screw is connected to the output end of the drag drive component through the transmission gear, and the other end of the drag ball screw is connected to the capture component, and the dragging of the capture component and the target adapter is achieved by dragging the ball screw to make a linear motion along the axial direction; The locking assembly is fixed to the housing assembly and is used to lock the target adapter and achieve electrical connection with the target adapter; The locking assembly includes at least 4 sets of locking mechanisms, a follower assembly, a locking drive assembly and a large gear; the locking mechanism, the locking drive assembly and the large gear are fixed to the housing assembly, the locking drive mechanism is connected to the large gear through gear meshing, and the large gear is connected to all locking mechanisms through gear meshing; the follower assembly is fixed to the cable for electrical connection, and the follower assembly is fixed to the locking mechanism; The locking mechanism includes a roller, an electrical connector, a connecting rod, a locking support frame, a movable component, a disc spring component, a small guide rail, a fixed bracket, and a locking ball screw; when locked, the roller is connected to the target adapter, and the electrical connector is electrically connected to the target adapter; The roller is connected to the connecting rod through a pin, the connecting rod is connected to the movable assembly through a pin, and the disc spring assembly is fixed to the movable assembly; The small guide rail is fixed to the housing assembly and connected to the locking support frame through an adapter; The fixing bracket and the bearing support are fixed on the housing assembly; The electrical connector and the follower assembly are fixed on the locking support frame; The locking ball screw nut is designed with a gear and fixed on the bearing support. After the locking ball screw passes through the fixed bracket and the movable component, it is fixedly connected with the locking support frame; The capture assembly includes a fixed ring, a wire rope assembly, a rotating ring, a one-dimensional force sensor, a slider assembly and a capture drive assembly; the fixed ring and the rotating ring are connected by a bearing; the two ends of the wire rope assembly are respectively connected to the fixed ring and the rotating ring, and there are at least three sets of wire rope assemblies, which are evenly distributed along the circumference of the fixed ring and the rotating ring; the capture drive assembly is fixed on the fixed ring, and the output end is connected to the rotating ring through a gear; at least three groups of slider assemblies are fixed on the fixed ring, evenly distributed along the axial direction of the fixed ring, and connected to the guide rail; the one-dimensional force sensor is fixed on the slider assembly; when the capture assembly is working, the capture drive assembly drives the rotating ring to rotate, driving one end of the wire rope assembly to move, so that the initial circle formed by the wire rope assembly shrinks, and the target adapter is captured.

2. The space robot arm end grasping mechanism according to claim 1, characterized in that: The capture component also includes two in-position switches, which are fixedly connected to the fixing ring and are used to indicate two position states of the capture component, namely, a capture start position and a capture end position.

3. The space robot arm end grasping mechanism according to claim 1, characterized in that: It also includes a controller, which is installed on the outside of the shell assembly and is used to control the capture drive assembly, the drag drive assembly, the locking drive assembly, and communicate with the mechanical arm.

4. The space robot arm end grasping mechanism according to claim 1, characterized in that: It also includes a six-dimensional force sensor connected to the bottom cover for measuring the force during the grasping process.

5. The space robot arm end grasping mechanism according to claim 4, characterized in that: It also includes a quick-change device connected to the six-dimensional force sensor to achieve on-track replacement of the combination of the shell component, the capture component, the locking component and the dragging component.

6. A grasping method of a grasping mechanism at the end of a space robot arm, characterized in that: Use the grabbing mechanism described in any one of claims 1 to 5 to sequentially capture, drag, and lock the target adapter: Capture operation: The capture drive assembly drives the rotating ring to rotate, driving one end of the wire rope assembly to move, so that the initial circle formed by the three sets of wire rope assemblies shrinks until the target adapter is captured; Drag operation: The drag driving assembly drives the drag ball screw to rotate through the transmission gear, and the screw nut moves linearly along the axial direction, dragging the capture assembly and the target adapter to move; During the dragging process, the housing assembly is coupled with the target adapter to position the end gripping mechanism and the target adapter, thereby achieving docking between the end gripping mechanism and the target adapter; Locking operation: The locking drive assembly drives the locking ball screw nut of the locking mechanism to rotate through the large gear, and the screw together with the locking support frame and the movable assembly moves linearly along the small guide rail to achieve locking and electrical connection of the target adapter.

7. The grasping method of the grasping mechanism at the end of a space robot arm according to claim 6, characterized in that: The capture, drag and lock operations are controlled by the controller.

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