A rigid-flexible coupling space robot for on-orbit assembly and servicing

Abstract

The application discloses a rigid-flexible coupling space robot for on-orbit assembly and service, and belongs to the technical field of aerospace. The robot comprises a central trunk, two rigid mechanical arms, a flexible arm base and a rope-driven continuous flexible mechanical arm. The end of the rigid mechanical arm is provided with an electromagnet; the flexible mechanical arm is formed by connecting a plurality of sections in series, each section comprising a section disc, a flexible support beam and two oppositely arranged driving ropes. The flexible arm base is provided with a bidirectional winding disc driving system corresponding to each section, the system simultaneously controls the expansion and contraction of the two driving ropes through a driving motor and a winding disc, the distance between the two driving ropes and the central axis of the flexible support beam is equal, the single-motor-driven section bidirectional bending is realized, and the mass of the driving system is greatly reduced. The application also provides a matching folding truss module. The robot has the stable bearing of the rigid arm and the flexible operation of the flexible arm, and is suitable for space station extravehicular assembly, large truss structure construction and other tasks.

Description

Technical Field

[0001] This invention belongs to the field of aerospace technology, specifically relating to a rigid-flexible coupled space robot for on-orbit assembly and servicing. Background Technology

[0002] Large-scale space structures, such as space-based solar power stations and large-scale space-based bioengineering platforms, cannot be manufactured and launched as finished products due to launch capacity limitations. They must be constructed using a modular launch-on-orbit assembly method. With the development of robotics technology, space robots have become a feasible method for on-orbit assembly and servicing. Among them, crawling robots, which require no propellant, are small in size, lightweight, and highly flexible, and can effectively perform on-orbit assembly and maintenance tasks. However, existing rigid mobile robots have limited operational capabilities in unstructured and confined spaces during assembly tasks. The dynamic coupling between the rigid arm and the space structure can easily induce vibrations, potentially leading to decreased installation accuracy and structural instability.

[0003] Flexible-arm robots possess more redundant degrees of freedom, resulting in greater maneuverability compared to fully rigid robots. Furthermore, the flexible contact between the robot and the structure reduces vibrations triggered by collisions, making interaction with astronauts safer. However, their load-bearing capacity and positioning accuracy are insufficient. Therefore, rigid-flexible coupled robots, combining rigid and flexible arms, represent a promising solution.

[0004] However, existing rigid-flexible coupling robot drive systems are bulky and not conducive to space launches; the drive method of flexible arms usually uses one motor to control one rope, resulting in a complex and heavy drive system; at the same time, there is a lack of standardized foldable truss modules that are compatible with robots and facilitate robot grasping and assembly. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a highly dexterous, low-disturbance, and lightweight rigid-flexible coupled space robot and its matching unfolding truss module.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a rigid-flexible coupled space robot for on-orbit assembly and servicing, comprising: A central torso; Two rigid robotic arms are mounted on both sides of the central torso. Each rigid robotic arm has multiple rotational degrees of freedom and its end effector is provided for adsorption and fixation. A flexible arm base is fixedly installed at the rear end of the central torso; A flexible robotic arm, the starting end of which is fixed to a flexible arm base, is a rope-driven continuous robotic arm, consisting of multiple segments connected in series. Each segment includes multiple segmented disks equidistantly distributed along an axis, a flexible support beam passing through and fixed to all the segmented disks, and two opposing drive ropes passing through guide holes on the segmented disks. Adjacent segments are connected in series via segment connectors, and the end of the flexible robotic arm is provided with end tools for grasping and manipulating. The flexible arm base is also equipped with a bidirectional winding reel drive system corresponding to each segment. Each bidirectional winding reel drive system includes a drive motor and a winding reel fixed on the output shaft of the drive motor. The winding reel is provided with two rope grooves with opposite directions of rotation, which respectively wind one end of two opposing drive ropes. The other ends of the two drive ropes pass through the guide channel in the flexible arm base, then through the guide holes located on both sides of the flexible support beam in the corresponding segment, and are finally fixed on the segment disc at the very end of the segment. The two drive ropes are equidistant from the central axis of the flexible support beam in the segment, so that when the drive motor rotates, one motor controls the absolute value of the extension and retraction of the two drive ropes to be equal, thereby driving the segment to bend in both directions.

[0007] The central trunk includes a trunk shell and an internal cavity. The trunk shell is provided with a rigid arm mounting interface and a flexible arm mounting interface. The internal cavity is provided with a battery mounting base and a control board mounting base.

[0008] The rigid robotic arm includes a first joint motor, a second joint motor, a first link, a second link, and an end effector mounting base; the first joint motor is mounted on the rigid arm mounting interface, and its output shaft is connected to the first link; the second joint motor is mounted on the end of the first link, and its output shaft is connected to the second link; the end effector mounting base is fixed to the end of the second link, and an end effector is mounted on it.

[0009] Both the end effector and the end tool are electromagnets.

[0010] The flexible arm base is fixed to the flexible arm mounting interface; the segmented disc is provided with a disc center hole, a guide hole and a mounting hole; the flexible support beam passes through the disc center hole and is fixed to the segmented disc with bolts through the mounting hole; the drive rope passes through the guide hole; adjacent segments are connected in series through segmented connectors.

[0011] On the other hand, the present invention also provides a folding truss module for use with the above-mentioned rigid-flexible coupling space robot. The folding truss module includes a first docking plane, a second docking plane, and a foldable scissor mechanism connecting the two. The scissor mechanism includes cross links and transition links. The cross links are hinged to each other in the middle, and the two ends of the transition links are respectively hinged to the ends of the cross links and the docking plane. It also includes a drive mechanism, mounted on the cross links, for driving the cross links to open or close; the docking plane is provided with male and female interfaces for connecting multiple folding truss modules end to end; iron plates are fixed on the cross links for the end effector of the rigid-flexible coupling space robot to be attracted.

[0012] The first docking plane and the second docking plane are respectively provided with a male sleeve head and a female sleeve head, which cooperate with each other to limit and guide during the unfolding process.

[0013] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a rigid-flexible coupling configuration combining a rigid and a flexible robotic arm. The rigid robotic arm is responsible for stable movement and fixation within the spatial structure, while the flexible robotic arm utilizes a rope-driven continuous structure to achieve multi-degree-of-freedom dexterity. This allows the robot to combine the high load-bearing capacity of a rigid arm with the high adaptability of a flexible arm, significantly improving its operational capabilities in confined, unstructured spatial environments. Simultaneously, the flexible contact effectively reduces the risk of collision-induced structural vibrations. Furthermore, this invention proposes a bidirectional cable reel drive system. Each segment's bidirectional bending requires only one drive motor. Two opposing drive ropes are wound around two grooves on the reel with opposite directions of rotation, ensuring that the distances of the two drive ropes from the central axis of the flexible support beam are equal. This automatically equalizes the absolute values ​​of the extension and retraction of the two drive ropes when the drive motor rotates, thereby precisely controlling the bidirectional bending of the flexible arm segments. Compared to the traditional approach of equipping each rope with a motor, this design significantly reduces the mass and volume of the drive system, making it particularly suitable for the stringent payload constraints of aerospace launches. Furthermore, by installing casters on the central torso, two rigid robotic arms, the flexible arm base, and the bottom of the flexible robotic arms, stable and low-damping planar sliding supports are provided for ground-based microgravity simulation experiments, facilitating the verification of the robot's motion and operational performance on the ground. Finally, this invention also provides a matching folding truss module. This module adopts a foldable scissor mechanism, folding in the launch state to save space, and being grasped and unfolded by the robot after entering orbit. The modules are standardized and connected in series via male and female interfaces. The iron plates on the cross links cooperate with the robot's electromagnet end effector to achieve reliable adsorption, grasping, and assembly between the robot and the truss module, providing a complete technical solution for the on-orbit construction of ultra-large space structures. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments are briefly introduced below.

[0015] Figure 1 This is a schematic diagram of the overall structure of the rigid-flexible coupled space robot provided in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the central torso provided in an embodiment of the present invention.

[0017] Figure 3 This is a schematic diagram of the rigid robotic arm provided in an embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram of the flexible robotic arm and bidirectional winding reel drive system provided in an embodiment of the present invention.

[0019] Figure 5 This is a schematic diagram of the bidirectional winding reel drive system provided in an embodiment of the present invention.

[0020] Figure 6 This is a structural schematic diagram of the unfolding truss unit provided in an embodiment of the present invention.

[0021] Figure 7 This is a schematic diagram of the structure after multiple folding truss units are connected according to an embodiment of the present invention.

[0022] Figure 8 This is a schematic diagram of the rigid-flexible coupling space robot grasping and unfolding truss module provided in an embodiment of the present invention.

[0023] Figure 9 This is a schematic diagram of the structure for installing universal wheels on a rigid-flexible coupled space robot provided in an embodiment of the present invention.

[0024] Figure 10 This is a photograph of the actual ground experimental platform provided in the embodiment of the present invention.

[0025] Figure 11 This is a photograph of a flexible robotic arm operating through a narrow space, as provided in an embodiment of the present invention.

[0026] Figure 12 This is a photograph of the actual module used in the docking mission through a narrow space, as provided in an embodiment of the present invention.

[0027] The meanings of the labels in the attached diagram are as follows: 10-Central torso; 11-Torso shell; 12-Internal cavity; 13-Rigid arm left mounting interface; 14-Rigid arm right mounting interface; 15-Flexible arm mounting interface; 20- Rigid robotic arm; 21- First joint motor; 22- Second joint motor; 23- First link; 24- Second link; 25- End effector mounting base; 26- End effector; 30-Flexible robotic arm; 31-Segmented disc; 310-Disc center hole; 311-Guide hole; 312-Mounting hole; 32-Flexible support beam; 33-Drive rope; 34-Segmented connector; 35-Flexible arm base; 36-End tool; 40 - Bidirectional winding reel drive system; 41 - Drive motor; 42 - Winding reel; 421 - First rope groove; 422 - Second rope groove; 50 - Folding Truss Module; 51 - First Dating Plane; 52 - Second Dating Plane; 53 - Male Interface; 54 - Female Interface; 55 - Male Sleeve Head; 56 - Female Sleeve Head; 57 - Cross Link; 58 - Adapter Member; 59 - Drive Mechanism; 60 - Iron Sheet; 70 - Universal wheel. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1 This embodiment provides a rigid-flexible coupled space robot for on-orbit assembly and servicing. (See also...) Figure 1 As shown, its space application configuration includes a central torso 10, two rigid robotic arms 20, a flexible arm base 35, and a flexible robotic arm 30.

[0030] Two rigid robotic arms 20 are respectively mounted on the left and right sides of the central torso 10. A flexible arm base 35 is fixedly mounted on the rear end (or front end, in this embodiment, the rear end is used as an example) of the central torso 10. The starting end of the flexible robotic arm 30 is fixed on the flexible arm base 35. In actual space applications, the robot moves and is fixed by adhering to the ferromagnetic surface of the space station or truss structure using electromagnets at the ends of the rigid robotic arms 20.

[0031] like Figure 2 As shown, the central torso 10 includes a torso shell 11, within which an internal cavity 12 is formed. The torso shell 11 is provided with rigid arm mounting interfaces (including a left rigid arm mounting interface 13 on the left and a right rigid arm mounting interface 14 on the right) and a flexible arm mounting interface 15. The internal cavity 12 contains a battery mounting bracket and a control board mounting bracket, used to secure the battery and control circuit board, respectively.

[0032] like Figure 3As shown, each rigid robotic arm 20 includes a first joint motor 21, a second joint motor 22, a first link 23, a second link 24, an end effector mounting base 25, and an end effector 26.

[0033] The first joint motor 21 is mounted on the rigid arm mounting interface of the central torso 10 (the left side is the rigid arm left mounting interface 13, and the right side is the rigid arm right mounting interface 14). Its output shaft is fixedly connected to one end of the first link 23 to realize the swinging of the rigid arm in the plane. The other end of the first link 23 is mounted with a second joint motor 22. The rotation axis of the second joint motor 22 is perpendicular to the rotation axis of the first joint motor 21. Its output shaft is fixedly connected to one end of the second link 24 to realize the torsion of the rigid arm in space. The other end of the second link 24 is fixedly connected to the end effector 26 through the end effector mounting seat 25. The end effector 26 is an electromagnet that generates magnetic force when energized and can be attracted to the ferromagnetic components of the spatial structure.

[0034] The flexible arm base 35 is bolted to the flexible arm mounting interface 15 at the rear end of the central body 10. The flexible arm base 35 has multiple independent guide channels inside to guide the drive ropes 33 of each segment smoothly into the flexible robotic arm 30. The flexible arm base 35 also has multiple mounting stations for fixing the various drive motors 41 in the bidirectional winding reel drive system 40.

[0035] like Figure 4 As shown, the flexible robotic arm 30 is a rope-driven continuous robotic arm, composed of multiple structurally identical sections connected in series. This embodiment uses two sections, referred to as the first section and the second section, respectively. The structure and working principle of the first section will be explained in detail below.

[0036] Each segment includes: multiple segmented discs 31, a flexible support beam 32, two opposing drive ropes 33, and segment connectors 34. The segmented discs 31 are annular, with a central hole 310 at the center. Multiple guide holes 311 and mounting holes 312 are evenly distributed along the circumference of the disc. The flexible support beam 32 is made of high-elasticity nickel-chromium alloy wire, which passes sequentially through the central holes 310 on each segmented disc 31 and is fixedly connected to each segmented disc 31 by bolts passing through the mounting holes 312. The multiple segmented discs 31 are equidistantly distributed along the axis of the flexible support beam 32, forming the skeleton of the flexible arm. The two drive ropes 33 are high-strength, low-elongation Dyneema ropes, which pass through the two guide holes 311 on either side (opposite) of the flexible support beam 32 on the segmented discs 31. Adjacent segments are connected in series via segment connectors 34, which are rigid short tubes with their ends fixedly connected to the end segment disk 31 of the preceding segment and the beginning segment disk 31 of the following segment, respectively. The end of the flexible robotic arm 30 is fixed with an end tool 36, which in this embodiment is an electromagnet used to grasp the unfolding truss module to be assembled.

[0037] Each section is configured with a bidirectional winding reel drive system 40. For example... Figure 5 As shown, the drive system includes a drive motor 41 and a cable reel 42. The drive motor 41 is fixedly mounted on the flexible arm base 35, and the cable reel 42 is fixed on its output shaft. The circumferential surface of the cable reel 42 is provided with a first cable groove 421 and a second cable groove 422, with opposite directions of rotation. One end of the first drive rope is fixed and wound in the first cable groove 421, and one end of the second drive rope is fixed and wound in the second cable groove 422. After the two drive ropes are led out from the cable reel 42, they pass through the corresponding guide channels in the flexible arm base 35, and then enter the first segment of the flexible robotic arm 30. They pass through the guide holes 311 located on both sides of the flexible support beam 32 in the segment, and are finally fixed to the segment disc 31 at the very end of the segment (for example, by knotting or crimping).

[0038] In the above arrangement, the two drive ropes are equidistant from the central axis of the flexible support beam 32 within the segment. When the drive motor 41 rotates in the forward direction, the winding reel 42 rotates in the forward direction, the first drive rope is wound up and contracts, the second drive rope is released and extends, and the flexible arm bends towards the side of the first drive rope; the opposite occurs when rotating in the reverse direction. Therefore, one drive motor can precisely control the bidirectional bending of one segment without generating additional internal forces, significantly reducing the mass of the drive system.

[0039] The second section is driven in the same way as the first section. Each section has its own independent drive motor and reel, which are all installed on the flexible arm base 35. The drive ropes pass through the corresponding guide channels in the flexible arm base, and then pass through the hollow channels (center hole 310 of the segment disc) of the preceding section to reach their respective sections and are fixed on the segment disc at the very end of the section.

[0040] Each segment's bidirectional bending requires only one drive motor, while omnidirectional bending in three-dimensional space requires two drive motors, and can be achieved through any combination of four-way bending.

[0041] The aforementioned rigid-flexible coupled space robot is mainly used for on-orbit grasping and assembling the basic unit of large space structures—the folding truss module. The following describes the specific structure of the folding truss module used in conjunction with this robot and its connection to the robot.

[0042] The folding truss module 50 is a basic unit for constructing large-scale space structures. It is folded during launch to save space and unfolds into a structural unit to be assembled after entering orbit. For example... Figure 6 As shown, the folding truss module 50 includes a first docking plane 51, a second docking plane 52, and a foldable scissor mechanism connecting the two. The scissor mechanism includes cross links 57 and connecting rods 58. The middle parts of the two sets of cross links 57 are hinged to each other through a revolute joint, and the two ends of the connecting rods 58 are respectively hinged to the ends of the cross links 57 and the docking plane. A drive mechanism 59 (such as a servo motor) is mounted on the cross links 57 to drive the cross links 57 to open or close. A male interface 53 is provided on the first docking plane 51, and a female interface 54 is provided on the second docking plane 52. Adjacent modules are connected end-to-end through the male and female interfaces (e.g., ...). Figure 7 (As shown). A male sleeve head 55 and a female sleeve head 56 are respectively provided on the first docking plane 51 and the second docking plane 52, which cooperate to guide and limit movement during deployment. An iron plate 60 is fixed to the cross link 57.

[0043] The way the robot works with the folding truss module is as follows: Figure 8 As shown: When the end effector 26 (electromagnet) at the end of the rigid robotic arm 20 is energized, it can be attracted to the iron plate 60 to fix the robot on the truss module; When the end tool 36 (electromagnet) at the end of the flexible robotic arm 30 is energized, it can be attracted to the iron plate 60 of another truss module to grasp and transport the module; After the robot grasps the module, it aligns its male interface 53 with the female interface 54 of the fixed module to complete the docking and assembly.

[0044] Example 2 In this embodiment, a ground-based microgravity simulation experimental platform was built to verify the motion performance and assembly function of the robot of the present invention on the ground. For example... Figure 9As shown, to facilitate the simulation of a microgravity environment on the ground, casters 70 are installed at the bottom of the robot prototype's central torso 10, the bottom of the two rigid robotic arms 20, the bottom of the flexible arm base 35, and the bottom of each segment of the flexible robotic arm 30. Figure 10 As shown, the experimental platform also includes an air-bearing precision optical platform, a low-drag Teflon plate, and a vision measurement system (industrial camera and April Tag marker). The entire robot is placed on the low-drag Teflon plate, where the casters 70 provide near-frictionless sliding support, thus simulating free movement in an on-track configuration.

[0045] One of the experimental tasks was "dock module traversing a narrow space." For example... Figure 11 As shown, the flexible robotic arm 30, under the control of the bidirectional reel drive system 40, precisely bends and passes through narrow gaps (the gap width is slightly larger than the diameter of the flexible arm) in the simulated truss structure. Figure 12 As shown, the flexible arm's end effector 36 (electromagnet) successfully grasped the target folding truss module and transported it to the docking position. The module docking was completed through the coordinated movement of the rigid and flexible arms. During the experiment, the vision system recorded the pose of each segment of the flexible arm in real time, verifying the accuracy of the robot's kinematic model and the control precision of the bidirectional reel drive system.

[0046] The above-mentioned ground experiments successfully verified the dexterous operation capability, narrow space traversal capability, and autonomous assembly capability of the rigid-flexible coupling space robot of the present invention in a simulated microgravity environment, providing a reliable technical foundation for on-orbit space applications.

[0047] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not describe all details exhaustively, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification.

Claims

1. A rigid-flexible coupled space robot for on-orbit assembly and servicing, characterized in that, include: A central torso (10); Two rigid robotic arms (20) are mounted on both sides of the central torso (10). Each rigid robotic arm (20) has multiple rotational degrees of freedom and its end is provided with an end effector (26) for adsorption and fixation. A flexible arm base (35) is fixedly installed at the rear end of the central torso (10); A flexible robotic arm (30) is fixed at its starting end to the flexible arm base (35). The flexible robotic arm (30) is a rope-driven continuous robotic arm, which is composed of multiple segments connected in series. Each segment includes multiple segment disks (31) distributed equidistantly along the axis, a flexible support beam (32) passing through all the segment disks (31) and fixed thereto, and two opposing drive ropes (33) passing through the guide holes (311) on the segment disks (31). Adjacent segments are connected in series through segment connectors (34). The end of the flexible robotic arm (30) is provided with an end tool (36) for grasping and manipulating. The flexible arm base (35) is also provided with a bidirectional winding reel drive system (40) corresponding to each segment. Each bidirectional winding reel drive system (40) includes a drive motor (41) and a winding reel (42) fixed on the output shaft of the drive motor (41). The winding reel (42) is provided with two rope grooves (421, 422) with opposite directions of rotation, which respectively wind one end of two opposing drive ropes (33). The other ends of the two drive ropes (33) pass through the guide channel in the flexible arm base (35) and then through the guide holes (311) on both sides of the flexible support beam (32) in the corresponding segment, and are finally fixed on the segment disc (31) at the end of the segment. The two drive ropes (33) are equidistant from the central axis of the flexible support beam (32) in the segment, so that when the drive motor (41) rotates, one motor controls the absolute value of the extension and retraction of the two drive ropes (33) to be equal, thereby driving the segment to bend in both directions.

2. The rigid-flexible coupled space robot according to claim 1, characterized in that, The central torso (10) includes a torso shell (11) and an internal cavity (12). The torso shell (11) is provided with a rigid arm mounting interface and a flexible arm mounting interface (15). The internal cavity (12) is provided with a battery mounting base and a control board mounting base.

3. The rigid-flexible coupled space robot according to claim 1, characterized in that, The rigid robotic arm (20) includes a first joint motor (21), a second joint motor (22), a first link (23), a second link (24), and an end effector mounting base (25); the first joint motor (21) is mounted on the rigid arm mounting interface, and its output shaft is connected to the first link (23); the second joint motor (22) is mounted on the end of the first link (23), and its output shaft is connected to the second link (24); the end effector mounting base (25) is fixed to the end of the second link (24), and an end effector (26) is mounted on it.

4. The rigid-flexible coupled space robot according to claim 1, characterized in that, Both the end effector (26) and the end tool (36) are electromagnets.

5. The rigid-flexible coupled space robot according to claim 2, characterized in that, The flexible arm base (35) is fixed to the flexible arm mounting interface (15).

6. The rigid-flexible coupled space robot according to claim 1, characterized in that, The segmented disc (31) is provided with a central hole (310), a guide hole (311) and a mounting hole (312); the flexible support beam (32) passes through the central hole (310) and is fixed to the segmented disc (31) with bolts through the mounting hole (312); the drive rope (33) passes through the guide hole (311); adjacent segments are connected in series by segmented connectors (34).

7. A folding truss module for use with the rigid-flexible coupling space robot according to any one of claims 1-6, characterized in that, The folding truss module (50) includes a first docking plane (51), a second docking plane (52), and a foldable scissor mechanism connecting the two. The scissor mechanism includes a cross link (57) and a transition link (58). The cross link (57) is hinged to each other in the middle, and the two ends of the transition link (58) are hinged to the ends of the cross link (57) and the docking plane, respectively. It also includes a drive mechanism (59) installed on the cross link (57) for driving the cross link (57) to open or close. The docking plane is provided with a male interface (53) and a female interface (54) for connecting the head and tail of multiple folding truss modules. An iron plate (60) is fixed on the cross link (57) for the end effector (26) of the rigid-flexible coupling space robot to be attracted.

8. The folding truss module according to claim 7, characterized in that, The first docking plane (51) and the second docking plane (52) are respectively provided with a male sleeve head (55) and a female sleeve head (56), which cooperate with each other to limit and guide each other during the unfolding process.

9. A rigid-flexible coupling space robot on-orbit assembly system, characterized in that, Includes the rigid-flexible coupling space robot as described in any one of claims 1-6 and the folding truss module as described in claim 7 or 8; the end effector (26) of the rigid-flexible coupling space robot cooperates with the iron plate (60) on the folding truss module by electromagnetic adsorption to realize the fixation of the robot on the truss module and the grasping of the truss module by the robot.

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