Cooperative type variable-stiffness mechanical arm for catching net

Abstract

The invention relates to the technical field of spaceflight, and discloses a catching net cooperative type variable-stiffness manipulator which comprises a bottom plate, three fingers are vertically arranged on the bottom plate, a supporting disc is installed on the bottom plate, a fixing disc is installed on the supporting disc, a catching net is arranged above the fixing disc, and a catching net motor, a variable-stiffness motor and a joint control motor are installed on the supporting disc. Winding columns are installed on driving shafts of the catching net motor and the joint control motor, the catching net is connected with the winding columns of the catching net motor through catching net driving ropes, inner side driving tendons and outer side driving tendons are arranged on the fingers, the inner side driving tendons are connected with the winding columns of the joint control motor, and the outer side driving tendons are connected with the joint control motor. And the outer side driving muscle tendon is connected with a variable stiffness mechanism mounted on the bottom plate through a stretching compensation spring. According to the capturing net cooperative type variable-rigidity manipulator, through the design of a variable-rigidity mechanism with the length of a cantilever capable of being adjusted, the rigidity adjusting range is widened, meanwhile, the magnetic control self-locking function and the capturing net function are combined, and flexible and safe grabbing of objects of different shapes and sizes is achieved.

Description

Technical Field

[0001] This invention relates to the field of aerospace technology, specifically to a net-catching cooperative variable stiffness manipulator. Background Technology

[0002] In recent years, with the rapid development of aerospace technology, space activities have become increasingly frequent, and the number of space debris has continued to increase, posing a serious threat to the safety of personnel and equipment in the space environment. In order to ensure the safety of personnel and equipment in the space environment, it is urgent to develop a space manipulator that can stably capture non-cooperative targets (such as space debris) under high radiation conditions.

[0003] Currently, existing methods for varying the stiffness of robotic arms are mainly divided into two categories: structural stiffness variation methods and material stiffness variation methods. Structural variable stiffness methods include antagonistic and lever-based types. Their basic principle is to construct biomimetic joints using motors or pneumatic muscles, and then use actuators, either individually or in synergy, to control joint deformation or adjust stiffness. Alternatively, the joint stiffness can be changed by adjusting the position of the lever fulcrum using a motor. However, antagonistic variable stiffness methods suffer from problems such as complex structures, low reliability, and difficulty in control.

[0004] Methods for varying material stiffness include blocking and smart material approaches. For example, filling a flexible cavity with particulate material and applying negative pressure to tightly bind the particles together transforms the material from a soft to a hard state, thus adjusting stiffness. Alternatively, external stimuli such as temperature, magnetic fields, or electric fields can alter the physical or chemical properties of materials like low-melting-point alloys, magnetorheological fluids, shape memory polymers, and polycaprolactone, thereby achieving variable stiffness. However, the elastic modulus of materials like shape memory polymers and polycaprolactone varies only slightly with temperature, resulting in a narrow range of stiffness adjustment.

[0005] Therefore, existing technologies cannot simultaneously meet the requirements of "wide stiffness adjustment range" and "flexible and safe grasping of objects of different shapes and sizes," and there is an urgent need for a new type of variable stiffness manipulator to solve the above-mentioned technical defects. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a net-catching and coordinated variable stiffness manipulator. Through the design of a variable stiffness mechanism with adjustable cantilever length, the stiffness adjustment range is improved, and combined with magnetic self-locking and net-catching functions, it can achieve flexible and safe grasping of objects of different shapes and sizes.

[0007] To achieve the above objectives, the present invention relates to a net-catching cooperative variable stiffness manipulator, comprising a base plate on which three fingers are vertically arranged at 120° intervals. These three fingers are evenly distributed at 120° intervals, allowing for uniform circumferential wrapping of objects during grasping, ensuring balanced force and preventing damage or slippage due to excessive local pressure. This adapts to the grasping needs of objects of different sizes and shapes. The fingers are mounted on the base plate via a base plate base. A support plate is fixedly mounted on the base plate within the area enclosed by the three fingers via a first support column. A fixed plate is mounted on the support plate via a second support column. The support plate and fixed plate are installed in layers via support columns, resulting in a compact structure that provides a stable mounting foundation for components such as motors and ropes, while reserving reasonable movement space to avoid component interference. A net is positioned above the fixed plate. A net-catching motor, a variable stiffness motor, and a joint control motor are mounted on the support plate. Winding columns are mounted on the drive shafts of both the net-catching motor and the joint control motor. The net-catching motor drives a rope that is connected to the net-catching motor. The winding post connection is used to flexibly wrap the grasped object. The finger is composed of several phalanges hinged in sequence. The finger is equipped with an inner driving tendon that controls its movement and an outer driving tendon that controls its stiffness. Both the inner and outer driving tendons are connected to the uppermost phalanx. The inner driving tendon is connected to the winding post of the joint control motor. The outer driving tendon is connected to a variable stiffness mechanism mounted on the base plate through a tension compensation spring. The variable stiffness mechanism adjusts its stiffness under the control of the variable stiffness motor. The net motor, variable stiffness motor, and joint control motor have clear division of labor, realizing independent control of wrapping, stiffness adjustment, and finger movement, respectively. With their coordinated cooperation, they can ensure both grasping flexibility and flexible and safe grasping. The dual-drive design of the inner driving tendon controlling movement and the outer driving tendon controlling stiffness is functionally separated yet coordinated. The rebound force of the tension compensation spring allows the finger to extend, so that finger movement and stiffness adjustment do not interfere with each other, improving control accuracy and adapting to the grasping needs of objects of different weights.

[0008] Preferably, the variable stiffness mechanism includes a turntable mounted on the base plate and three variable stiffness units evenly distributed along the circumference of the turntable. The turntable is connected to the drive shaft of the variable stiffness motor. Each variable stiffness unit includes a bracket and a spring plate. The high-stiffness end of the spring plate is fixedly connected to the bracket, and the low-stiffness end is connected to a connector. The connector is connected to the tension compensation spring. A slidable slider is fitted onto the spring plate. The slider is connected to a guide rail via a positioning pin below. The guide rail is slidably mounted in a guide rail groove on the base plate. A drive rod is mounted on the other end of the guide rail. The turntable has an arc-shaped guide groove, and the drive rod is located within the guide groove. When the variable stiffness motor rotates, it drives the turntable to rotate, which in turn drives the drive rod to move inward or outward through the guide groove. The turntable drives the guide groove to move the guide rail inward and outward. The length of the spring cantilever is indirectly adjusted by the slider, achieving continuous and precise adjustment of stiffness. Compared with traditional fixed stiffness or segmented stiffness structures, it has a wider range of applications. At the same time, the spring adopts a high and low stiffness segmented design, combined with the cantilever length adjustment, further expanding the range of stiffness variation. It can gently grasp fragile objects and firmly clamp heavy objects.

[0009] Preferably, the hinge between adjacent phalanges of the finger is a rotary joint, including a ball bearing located on the upper part of one phalanx and a shoulder located on the lower part of the adjacent phalanx. The ball bearing and the shoulder cooperate to form the rotary joint. The hinge also has a magnetically controlled self-locking mechanism, which includes a coil and a pin located inside the coil. A return spring is fitted on the pin, with one end of the return spring abutting against the upper top surface of the coil and the other end abutting against the lower bottom surface of the pin. The lower end of the phalanx is arc-shaped and has several pin holes. When the coil... When the coil is energized, the top of the pin inserts into the pin hole to achieve self-locking. When the power is off, the pin resets and unlocks under the action of the return spring. The extension and retraction of the pin is controlled by the coil's power on and off through the magnetic self-locking mechanism. When energized and self-locked, it can be fixed at any finger joint angle to prevent joint loosening during grasping and improve grasping stability under complex working conditions. It automatically unlocks when the power is off, making operation convenient and not affecting the normal movement cycle of the fingers. At the same time, the pin cooperates with multiple pin holes to achieve precise self-locking at multiple angles, adapting to the fixation requirements of different grasping postures and further improving grasping adaptability.

[0010] Preferably, the hinge within the finger is also equipped with an angle sensor to detect the relative angle between two adjacent phalanges. By collecting the relative angle data between the phalanges in real time, precise feedback is provided to the joint control motor, realizing closed-loop control of finger movement. This makes the grasping action more precise and can adjust the posture to fit the contour of the object. At the same time, the angle information provides a reference for variable stiffness adjustment, which can match the optimal stiffness according to the bending angle of the phalanges, avoiding grasping failure caused by the mismatch between stiffness and posture, and improving the level of intelligent control.

[0011] Preferably, the outer shell of the knuckle is divided into left and right parts, which are connected by screws, and the coil is clamped and fixed by the two parts of the knuckle.

[0012] Preferably, a channel is provided between the two parts of the phalanx for the medial and lateral driving tendons to pass through. Since the medial and lateral driving tendons are embedded in the channel, wear, entanglement, or interference with other components caused by exposure are avoided, effectively protecting the tendons and extending their service life. In addition, the channel guides the tendon movement, ensuring accurate tendon transmission trajectory, avoiding power transmission loss or finger movement jamming caused by deviation, and improving transmission reliability and finger movement accuracy.

[0013] Preferably, the base plate has a transverse cylindrical pin. The inner driving tendon bypasses the cylindrical pin and connects to the winding post of the joint control motor. The net driving rope bypasses the cylindrical pin and connects to the winding post of the net driving motor. By changing the force transmission direction of the inner driving tendon and the net driving rope through the cylindrical pin, the motor can be centrally installed on the support plate, optimizing the overall structural layout, reducing space occupation, making the robot more compact, and the smooth surface of the cylindrical pin reduces friction loss during tendon and rope movement, reduces energy waste, protects the tendon and rope, and extends the service life of the transmission components.

[0014] Preferably, a sleeve is provided on the inward side of the finger. The net drive rope first passes upward through the sleeve and then downward to connect with the winding post of the net motor. The sleeve provides precise guidance and limitation for the net drive rope, preventing the rope from deviating, swaying, or rubbing against the finger shell during movement. This ensures that the net's contraction / extension action is smooth and precise, reduces rope wear, improves the working stability and service life of the net, and ensures the reliable realization of the flexible wrapping function.

[0015] Preferably, a return spring is provided between the center of the net and the fixed plate. After the net is grabbed, the return spring can automatically pull the net back to the initial position, eliminating the need for an additional reset drive structure and simplifying the control logic and mechanism complexity.

[0016] Preferably, the outer side of the base plate has an arc-shaped groove for the tension compensation spring to pass through, providing a dedicated movement space for the tension compensation spring, avoiding interference between the spring and the base plate or other components, ensuring smooth spring extension and contraction, not affecting the variable stiffness adjustment and finger reset action, and the groove also acts as a limit for the tension compensation spring, fixing its movement trajectory, ensuring accurate power transmission between the tension compensation spring and the outer drive tendon and variable stiffness mechanism, improving the stability and reliability of variable stiffness adjustment; at the same time, it reduces spring wear and extends its service life.

[0017] Compared with the prior art, the present invention has the following advantages: 1. Wide range of variable stiffness: Based on the variable fulcrum cantilever beam model, the stiffness can be continuously adjusted by adjusting the length of the spring plate cantilever. Combined with the high and low stiffness segmented design, the range of stiffness variation is significantly better than the traditional material variable stiffness method. 2. Strong gripping stability: The built-in magnetic self-locking mechanism can lock at any joint angle, preventing joint loosening during gripping and improving gripping reliability under complex working conditions; 3. Excellent flexible wrapping effect: The net and the capture net are designed to work together so that after the fingers grab the object, the net will follow the shape of the object and wrap it, effectively dispersing the contact pressure and avoiding damage to fragile or irregular objects; 4. High adaptability: The three fingers are distributed at 120°, and with the adjustable stiffness and flexibility of the net, it can be adapted to objects of different shapes and weights, and is especially suitable for capturing non-cooperative targets such as space debris. 5. Compact and reliable structure: It adopts a modular design, with integrated motor installation and embedded drive tendons. The structure is simple and the operation is stable. The material selection takes into account both strength and lightweight, meeting the needs of special scenarios such as space applications. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the net-catching cooperative variable stiffness manipulator of the present invention; Figure 2 for Figure 1 Schematic diagram of the central support plate; Figure 3 for Figure 1 Schematic diagram of a medium-stiffness mechanism; Figure 4 for Figure 1 Top view; Figure 5 for Figure 1 Schematic diagram of the structure of the central fixed plate; Figure 6 for Figure 1 An exploded image of the middle finger.

[0019] The components in the diagram are labeled as follows: 1. Base plate; 2. Finger; 3. Base plate base; 4. First support column; 5. Support plate; 6. Second support column; 7. Fixing plate; 8. Net; 9. Net motor; 10. Variable stiffness motor; 11. Joint control motor; 12. Winding column; 13. Dentium; 14. Medial drive tendon; 15. Lateral drive tendon; 16. Tension compensation spring; 17. Variable stiffness mechanism; 18. Turntable; 19. Variable stiffness unit; 20. Bracket; 21. Spring plate; 22. Connector; 23. Slider; 24. Positioning pin; 25. Guide rail; 26. Guide rail groove; 27. Drive rod; 28. Guide groove; 29. ​​Rotary joint; 30. Ball bearing; 31. Shoulder; 32. Coil; 33. Pin; 34. Return spring; 35. Pin hole; 36. Angle sensor; 37. Screw; 38. Cylindrical pin; 39. Sleeve; 40. Return spring; 41. Groove; 42. Net drive rope; 131. Proximal phalanx; 132. Middle phalanx; 133. Distal phalanx. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0021] Example 1 like Figure 1 and Figure 2 As shown, a net-catching cooperative variable stiffness manipulator includes a base plate 1. Three fingers 2 are vertically arranged at 120° intervals on the base plate. The fingers 2 are mounted on the base plate 1 via a base plate base 3. A support plate 5 is fixedly mounted on the base plate 1 within the area enclosed by the three fingers 2 via a first support column 4. A fixed plate 7 is mounted on the support plate 5 via a second support column 6. A net 8 is positioned above the fixed plate 7. A net catching motor 9, a variable stiffness motor 10, and a joint control motor 11 are mounted on the support plate 5. Winding columns 12 are mounted on the drive shafts of both the net catching motor 9 and the joint control motor 11. The net 8 is driven by a net catching drive rope. The cable 42 is connected to the winding post 12 of the net-catching motor 9 and is used to flexibly wrap the captured object. The finger 2 is composed of several phalanges 13 that are hinged in sequence. The finger 2 is provided with an inner driving tendon 14 that controls its movement and an outer driving tendon 15 that controls its stiffness. Both the inner driving tendon 14 and the outer driving tendon 15 are connected to the uppermost phalange 13. The inner driving tendon 14 is connected to the winding post 12 of the joint control motor 11. The outer driving tendon 15 is connected to a variable stiffness mechanism 17 mounted on the base plate 1 through a tension compensation spring 16. The variable stiffness mechanism 17 adjusts its stiffness under the control of the variable stiffness motor 10.

[0022] When used in this embodiment, the following stages are included: 1. Preparation stage: The net-catching motor 9, the variable stiffness motor 10 and the joint control motor 11 are reset, the spring plate 21 of the variable stiffness mechanism 17 is at the initial cantilever length, and the finger 2 remains in an extended state. 2. Grasping phase: The joint control motor 11 rotates, which pulls the finger 2 to bend through the inner drive tendon 14, so that the finger 2 approaches and contacts the object. According to the weight of the object, the variable stiffness motor 10 drives the variable stiffness mechanism 17 to achieve stiffness adaptation of the finger 2. 3. Wrapping stage: The net motor 9 rotates, tightening the net drive rope 42, and the net 8 wraps around the object according to its shape, further improving the stability of the grasp; 4. Release phase: Net motor 9 rotates in the opposite direction, net 8 resets, joint control motor 11 rotates in the opposite direction, finger 2 extends, and the object is released.

[0023] Example 2 like Figure 1 and Figure 2 As shown, a net-cooperative variable stiffness manipulator includes a base plate 1. Three fingers 2, arranged vertically at 120° angles, are mounted on the base plate 1 via a base 3. A support plate 5 is fixedly mounted on the base plate 1 within the area enclosed by the three fingers 2 via a first support column 4. A fixed plate 7 is mounted on the support plate 5 via a second support column 6. A net 8, circular in shape with a radius of 48mm, is positioned above the fixed plate 7. A return spring 40 is located between the center of the net 8 and the fixed plate 7. A net-catching motor 9, a variable stiffness motor 10, and a joint control motor 11 are mounted on the support plate 5. Winding columns 12 are mounted on the drive shafts of both the net-catching motor 9 and the joint control motor 11. The net 8 is connected to the winding columns 12 of the net-catching motor 9 via a net-catching drive rope 42, used for flexibly wrapping the grasped object. Each finger 2 is composed of several knuckles 13 sequentially hinged. In this embodiment, combined with... Figure 6 As shown, there are three phalanges 13, namely the proximal phalange 131, the middle phalange 132, and the distal phalange 133. The finger 2 is provided with an inner driving tendon 14 to control its movement and an outer driving tendon 15 to control its stiffness. Both the inner driving tendon 14 and the outer driving tendon 15 are connected to the uppermost phalange 13. The inner driving tendon 14 is connected to the winding column 12 of the joint control motor 11. The outer driving tendon 15 is connected to a variable stiffness mechanism 17 mounted on the base plate 1 through a tension compensation spring 16. The variable stiffness mechanism 17 adjusts its stiffness under the control of the variable stiffness motor 10.

[0024] In this embodiment, combined with Figure 3 and Figure 4As shown, the variable stiffness mechanism 17 includes a turntable 18 mounted on a base plate 1 and three variable stiffness units 19 evenly distributed along the circumference of the turntable 18. The turntable 18 is connected to the drive shaft of the variable stiffness motor 10. Each variable stiffness unit 19 includes a bracket 20 and a spring plate 21. The high-stiffness end of the spring plate 21 is fixedly connected to the bracket 20, and the low-stiffness end is connected to a connector 22. Specifically, the spring plate 21 is made of 301 stainless steel, with a thickness of 0.2 mm and a width of 5 mm for the low-stiffness portion, and a thickness of 0.6 mm for the high-stiffness portion. The width is 10mm. The connector 22 is connected to the tension compensation spring 16. A sliding slider 23 is sleeved on the spring plate 21. The slider 23 is connected to the guide rail 25 through the positioning pin 24 below. The guide rail 25 is slidably installed in the guide rail groove 26 on the base plate 1. The other end of the guide rail 25 is equipped with a drive rod 27. The turntable 18 is provided with an arc-shaped guide groove 28. The drive rod 27 is in the guide groove 28. When the variable stiffness motor 10 rotates, it drives the turntable 18 to move, and then drives the drive rod 27 to move inward or outward through the guide groove 28.

[0025] Meanwhile, in this embodiment, combined with Figure 6 As shown, the hinge between adjacent knuckles 13 of finger 2 is a rotary joint 29 with a maximum rotation angle of approximately 90°. It includes a ball bearing 30 located on the upper part of one knuckle 13 and a shoulder 31 located on the lower part of the adjacent knuckle 13. The ball bearing 30 and the shoulder 31 cooperate to form the rotary joint 29. The hinge is also equipped with a magnetic self-locking mechanism, which includes a coil 32 and a pin 33 located inside the coil 32. A return spring 34 is fitted on the pin 33. One end of the return spring 34 abuts against the upper top surface of the coil 32, and the other end abuts against the lower bottom surface of the pin 33. The lower end of the knuckle 13 is arc-shaped and has several pin holes 35 distributed thereon. In this embodiment, each pin hole 35 is spaced 10° apart. When the coil 32 is energized, the top of the pin 33 inserts into the pin hole 35 to achieve self-locking. When the power is off, the pin 33 resets and unlocks under the action of the return spring 34.

[0026] When used in this embodiment, the following stages are included: 1. Preparation stage: The net-catching motor 9, the variable stiffness motor 10 and the joint control motor 11 are reset, the net 8 is in the initial position under the action of the return spring 40, the coil 32 is de-energized and unlocked, the spring plate 21 of the variable stiffness mechanism 17 is in the initial cantilever length, and the finger 2 remains in the extended state. 2. Grasping stage: The joint control motor 11 rotates, which pulls the finger 2 to bend through the inner drive tendon 14, so that it approaches and contacts the object. According to the weight of the object, the variable stiffness motor 10 drives the turntable 18 to rotate, adjusts the extension and retraction of the guide rail 25, and changes the cantilever length of the spring plate 21 to achieve stiffness adaptation of the finger 2. 3. Locking stage: After finger 2 is in contact with the object, coil 32 is energized, and pin 33 is inserted into the corresponding pin hole 35 to fix the joint angle and prevent the object from slipping. 4. Wrapping stage: The net motor 9 rotates, tightening the net drive rope 42, and the net 8 wraps around the object according to its shape, further improving the stability of the grasp; 5. Release phase: Net motor 9 rotates in the reverse direction, net 8 resets, coil 32 is de-energized and unlocked, joint control motor 11 rotates in the reverse direction, finger 2 extends, and the object is released.

[0027] In addition, in the above embodiment, an angle sensor 36 can be provided at the hinge point within the finger 2 to detect the relative angle between two adjacent knuckles 13. By collecting the relative angle data between the knuckles 13 in real time, precise feedback is provided to the joint control motor 11, realizing closed-loop control of the finger 2's movement. This makes the grasping action more precise and allows the finger to adjust its posture to conform to the object's contour. At the same time, the angle information provides a reference for variable stiffness adjustment, allowing the optimal stiffness to be matched according to the bending angle of the knuckles 13, avoiding grasping failure caused by a mismatch between stiffness and posture, and improving the level of intelligent control. In the above embodiment, the outer shell of the knuckle 13 is divided into left and right parts, which are connected by screws 37. The coil 32 is clamped and fixed by the two parts of the knuckle 13. A channel is left between the two parts of the knuckle 13 for the inner driving tendon 14 and the outer driving tendon 15 to pass through. Since the inner driving tendon 14 and the outer driving tendon 15 are embedded in the channel, wear, entanglement or interference with other components caused by exposure are avoided, effectively protecting the tendons and extending their service life. In addition, the channel plays a guiding role in tendon movement, ensuring the accuracy of tendon transmission trajectory, avoiding power transmission loss or finger movement jamming caused by deviation, and improving transmission reliability and finger movement accuracy.

[0028] In addition, the base plate 3 has a transverse cylindrical pin 38 inside. The inner driving tendon 14 passes around the cylindrical pin 38 and connects to the winding post 12 of the joint control motor 11. The net driving rope 42 passes around the cylindrical pin 38 and connects to the winding post 12 of the net motor 9. The outer side of the base plate 3 has an arc-shaped groove 41 for the tension compensation spring 16 to pass through. A sleeve 39 is provided on the inner side of the finger 2. The net driving rope 42 first passes upward through the sleeve 39 and then downward to connect to the winding post 12 of the net motor 9.

[0029] In the above embodiments, the rotating joint 29, the outer shell of the knuckle 13, and the turntable 18 are 3D printed using aluminum alloy materials, while the rest are made of white resin materials.

[0030] In the above embodiments, combined with Figure 5As shown, the second support column 6 between the fixed plate 7 and the support plate 5 adopts three ear-shaped support columns. The fixed plate 7 has three pairs of M2 threaded holes, which are positioned corresponding to the M2 threaded holes of the ear-shaped support columns. The fixed plate 7 and the ear-shaped support columns can be fastened together by screws. A 5mm diameter round hole is opened at the bottom of the ear-shaped support column. The first support column 4 between the base 1 and the support plate 5 adopts a column body. The column body has round holes of the same size in the same coaxial position. It is tightened by a threaded rod. The support plate 5 and the column body of the base 1 adopt a clearance fit. The support plate 5 and the column body are also fastened together by bolts.

[0031] This invention relates to a net-cooperative variable stiffness manipulator with a wide range of variable stiffness: based on a variable fulcrum cantilever beam model, the stiffness is continuously adjusted by adjusting the cantilever length of the spring plate 21. Combined with a segmented design of high and low stiffness, the range of stiffness variation is significantly better than traditional material variable stiffness methods. It also boasts strong grasping stability: a built-in magnetic self-locking mechanism allows locking at any joint angle, preventing joint loosening during grasping and improving grasping reliability under complex conditions. Furthermore, it offers excellent flexible wrapping: the net 8 is designed in a cooperative manner, with the fingers 2 grasping and the net 8 conforming to the shape of the object, effectively dispersing contact pressure and preventing damage to fragile or irregular objects. It is highly adaptable: the three fingers 2 are distributed at 120°, and together with the adjustable stiffness and flexible net 8, it can adapt to objects of different shapes and weights, especially suitable for capturing non-cooperative targets such as space debris. Finally, it features a compact and reliable structure: adopting a modular design, integrated motor installation, and embedded drive tendons, resulting in a simple structure and stable operation. The material selection balances strength and lightweight, meeting the needs of special scenarios such as space applications.

[0032] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims.

[0033] The aspects disclosed in this specification and claims are merely examples, and therefore, this specification and claims are not limited to the details shown. In the foregoing description, detailed descriptions of relevant known functions or configurations have been omitted where it would unnecessarily obscure the focus of this specification and claims.

[0034] Finally, it should be noted that the above description is a further detailed explanation of the invention in conjunction with specific embodiments. It should not be considered that the specific implementation of the invention is limited to these descriptions. For those skilled in the art, any simple substitutions made without departing from the concept of the invention should be considered within the scope of protection of this invention. The above embodiments are merely representative examples of the invention. Obviously, the invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the invention should be considered within the scope of protection of this invention.

Claims

1. A net-catching cooperative variable stiffness manipulator, comprising a base plate (1), wherein three fingers (2) are vertically arranged at 120° intervals on the base plate, the fingers (2) are mounted on the base plate (1) via a base plate base (3), and a support plate (5) is fixedly mounted on the base plate (1) within the area enclosed by the three fingers (2) via a first support column (4), and a fixed plate (7) is mounted on the support plate (5) via a second support column (6), characterized in that: A net (8) is provided above the fixed plate (7). A net-catching motor (9), a variable stiffness motor (10), and a joint control motor (11) are installed on the support plate (5). A winding post (12) is installed on the drive shaft of the net-catching motor (9) and the joint control motor (11). The net (8) is connected to the winding post (12) of the net-catching motor (9) through the net-catching drive rope (42) for flexibly wrapping the captured object. The finger (2) is composed of several phalanges (13) that are hinged in sequence. The finger (2) is equipped with a control device to move it. The inner driving tendon (14) and the outer driving tendon (15) that controls its stiffness are both connected to the uppermost phalanx (13). The inner driving tendon (14) is connected to the winding post (12) of the joint control motor (11). The outer driving tendon (15) is connected to a variable stiffness mechanism (17) mounted on the base plate (1) via a tension compensation spring (16). The variable stiffness mechanism (17) adjusts its stiffness under the control of the variable stiffness motor (10).

2. The net-catching cooperative variable stiffness manipulator as described in claim 1, characterized in that: The variable stiffness mechanism (17) includes a turntable (18) mounted on the base plate (1) and three variable stiffness units (19) evenly distributed along the circumference of the turntable (18). The turntable (18) is connected to the drive shaft of the variable stiffness motor (10). Each variable stiffness unit (19) includes a bracket (20) and a spring plate (21). The high-stiffness end of the spring plate (21) is fixedly connected to the bracket (20), and the low-stiffness end is connected to a connector (22). The connector (22) is connected to the tension compensation spring (16). A spring plate (21) is fitted with... A sliding slider (23) is connected to a guide rail (25) via a positioning pin (24) below. The guide rail (25) is slidably installed in a guide rail groove (26) on the base plate (1). A drive rod (27) is installed at the other end of the guide rail (25). An arc-shaped guide groove (28) is provided on the turntable (18). The drive rod (27) is in the guide groove (28). When the variable stiffness motor (10) rotates, it drives the turntable (18) to move, and then drives the drive rod (27) to move inward or outward through the guide groove (28).

3. The net-catching cooperative variable stiffness manipulator as described in claim 1, characterized in that: The hinge between adjacent phalanges (13) of the finger (2) is a rotary joint (29), including a ball bearing (30) on the upper part of one phalanx (13) and a shoulder (31) on the lower part of the adjacent phalanx (13). The ball bearing (30) and the shoulder (31) cooperate to form the rotary joint (29). The hinge is also provided with a magnetic self-locking mechanism, which includes a coil (32) and a pin (33) inside the coil (32). A return spring (34) is fitted on the pin (33). One end of the return spring (34) abuts against the top surface of the coil (32), and the other end abuts against the bottom surface of the pin (33). The lower end of the finger joint (13) is arc-shaped and has several pin holes (35). When the coil (32) is energized, the top of the pin (33) is inserted into the pin hole (35) to achieve self-locking. When the power is off, the pin (33) is reset and unlocked under the action of the return spring (34).

4. The net-catching cooperative variable stiffness manipulator as described in claim 1, characterized in that: An angle sensor (36) is also provided at the hinge point inside the finger (2) to detect the relative angle between two adjacent phalanges (13).

5. The net-catching cooperative variable stiffness manipulator as described in claim 3, characterized in that: The outer shell of the knuckle (13) is divided into left and right parts, which are connected by screws (37). The coil (32) is clamped and fixed by the two parts of the knuckle (13).

6. The net-catching cooperative variable stiffness manipulator as described in claim 3, characterized in that: A channel is left between the two parts of the phalanx (13) for the medial driving tendon (14) and the lateral driving tendon (15) to pass through.

7. The net-catching cooperative variable stiffness manipulator as described in claim 1, characterized in that: The base plate (3) has a transverse cylindrical pin (38) inside. The inner driving tendon (14) passes around the cylindrical pin (38) and is connected to the winding post (12) of the joint control motor (11). The net driving rope (42) passes around the cylindrical pin (38) and is connected to the winding post (12) of the net motor (9).

8. The net-catching cooperative variable stiffness manipulator as described in claim 1, characterized in that: The finger (2) has a sleeve (39) on the inward side. The net drive rope (42) first passes upward through the sleeve (39) and then downward to connect with the winding post (12) of the net motor (9).

9. The net-catching cooperative variable stiffness manipulator as described in claim 1, characterized in that: A return spring (40) is provided between the center of the net (8) and the fixed plate (7).

10. The net-catching cooperative variable stiffness manipulator as described in claim 1, characterized in that: The base plate (3) has an arc-shaped groove (41) on its outer side for the tension compensation spring (16) to pass through.

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