An underactuated dexterous hand based on tendon cable transmission and SMA locking

Abstract

The present invention discloses an under-actuated dexterous hand based on tendon transmission and SMA locking, comprising a cover plate, a shell assembly, a power drive assembly, a four-finger assembly, a tendon and a self-locking assembly, wherein the cover plate is located above the shell assembly, and a power drive assembly is provided between the cover plate and the shell assembly, a tendon is provided on one side of the power drive assembly, the tendon is connected to the four-finger assembly through a redirecting pulley, and a self-locking assembly is provided in the four-finger assembly, and the shell assembly comprises a shell and a plurality of redirecting pulleys fixed above the shell; the power drive assembly comprises a motor body, a motor cover plate and a disc, and a front groove and a rear groove are provided on the edge of the disc; the present invention adopts the above-mentioned under-actuated dexterous hand based on tendon transmission and SMA locking, adopts a single motor to drive multiple fingers, has a compact structure, and through a reasonable winding layout, a single motor can drive multiple fingers, and the self-locking structure is simple and easy to control.

Description

Technical Field

[0001] The present invention relates to the technical field of under-actuated dexterous hands, and in particular to an under-actuated dexterous hand based on tendon cable transmission and SMA locking. Background Art

[0002] Tendon-driven dexterous hands utilize a bionic tendon-bone transmission mechanism, replacing traditional rigid links with flexible cables. This design combines key advantages such as lightweight, high load-to-weight ratio, and smooth movement, demonstrating its irreplaceable value in applications such as medical prosthetics, industrial collaborative robots, and space exploration. Its key significance lies in: first, the flexible transmission significantly reduces mechanical shock, improving the safety of human-robot interactions; second, the strategic layout of the tendons allows the dexterous hand to adapt to complex grasping tasks in unstructured environments (such as enveloping irregular objects). In recent years, with the advancement of biomimetics and smart materials, research in this field has gradually evolved from basic transmission design to multi-finger coordination. Early drive schemes for tendon-driven dexterous hands achieved high dexterity through multiple motors independently controlling each finger, but this system complexity was excessive, and the motors increased the overall weight and size of the dexterous hand. Later, research on tendon-driven dexterous hands focused on lightweighting, aiming for coupled transmission with a single motor, but this compromised the control of some fingers. Current cutting-edge research is exploring the use of smart materials (such as shape memory alloys and electroactive polymers) to strike a balance between drive efficiency and control. Despite this, existing technologies still find it difficult to break through key bottlenecks such as multi-finger synchronous movement under a single drive source, locked state tension management and long-term reliability, which restricts their application in high-end scenarios such as precision surgical instruments and high-sensitivity industrial fixtures.

[0003] Against this backdrop, achieving multi-finger coordinated motion in a lightweight, low-power dexterous hand through innovative drive structures and material technologies has become a core challenge in this field. Despite significant progress in tendon-tethered drive technology, its practical application still faces multiple bottlenecks. First, there's an inherent conflict between flexibility and lightweight design. While multi-motor solutions enable independent finger control, redundant drive units significantly increase overall weight and energy consumption. Single-motor integrated solutions often lose selective control due to transmission coupling issues, making them unsuitable for complex grasping tasks. Second, traditional reset mechanisms rely on passive elastic elements (such as springs). Long-term use can lead to reset delays or accuracy degradation due to material fatigue, and they struggle to achieve rapid response under sudden loads. Furthermore, when some fingers are locked, the tendon-tethered system experiences tension imbalance, leading to energy redistribution and a surge in load on adjacent transmission paths. This not only impacts the motion accuracy of unlocked fingers but also accelerates wear of the mechanism. Furthermore, existing solutions suffer from significant shortcomings in energy efficiency management. The standby power consumption and thermal management burden of the multi-motor system further limit the device's endurance and stability. Summary of the Invention

[0004] The purpose of the present invention is to provide an under-actuated dexterous hand based on tendon cable transmission and SMA locking, which uses a single motor to drive multiple fingers, has a compact structure, and reduces overall weight and complexity.

[0005] The present invention provides an under-actuated dexterous hand based on tendon transmission and SMA locking, comprising a cover plate, a shell assembly, a power drive assembly, a four-finger assembly, a tendon and a self-locking assembly, wherein the cover plate is located above the shell assembly, a power drive assembly is provided between the cover plate and the shell assembly, a tendon is provided on one side of the power drive assembly, the tendon is connected to the four-finger assembly via a redirecting pulley, a self-locking assembly is provided in the four-finger assembly, the shell assembly comprises a shell and a plurality of redirecting pulleys fixed above the shell; the power drive assembly comprises a motor body, a motor cover plate and a disc, the edge of the disc is provided with a front groove and a rear groove; The four-finger assembly includes a thumb assembly, an index finger assembly, a middle finger assembly and a ring finger assembly. The thumb assembly, index finger assembly, middle finger assembly and ring finger assembly are all provided with a base plate, a guide rail, a slider, a slider plate, a finger body and a thumb cover plate. The base plate and the shell of the index finger assembly, middle finger assembly and ring finger assembly are designed with an integrated processing. The two ends of the tendon rope are respectively fixed to the front groove and the rear groove of the disc. The tendon rope passes through several redirecting pulleys in sequence to form a closed loop path. The thumb assembly is provided with a side swing motor, and the self-locking assembly includes a thumb self-locking assembly and an index finger self-locking assembly, a middle finger self-locking assembly and a ring finger self-locking assembly.

[0006] Preferably, the thumb SMA wire in the thumb self-locking assembly is wound and fixed on the thumb SMA wire pad, the front end of the thumb SMA wire pad is fixed on the thumb bottom plate, and the rear end of the thumb SMA wire pad is fixed on the thumb cover plate.

[0007] Preferably, a motor cover is provided on the outside of the motor body, and the motor body includes a motor back cover, a motor, a flange, a reducer and a motor front cover; the disc is connected to one end of the output shaft of the reducer in the motor body, the other end of the input shaft of the reducer is connected to the motor through a flange, the other end of the motor is connected to the motor back cover, and a motor front cover is provided on the outside of the reducer.

[0008] Preferably, the base plate in the thumb assembly is connected to the shell through a rotating pair, a guide rail is provided on the base plate, the guide rail and the slider are slidably connected, the slider and the slider plate are fixedly connected, the finger body is connected to the slider plate through a hinge, a thumb cover plate is provided above the finger body, and the guide rails in the index finger assembly, the middle finger assembly and the ring finger assembly are connected to the shell.

[0009] Preferably, the thumb assembly is provided with a side-swing motor, and the side-swing motor directly drives the thumb base plate to rotate around the vertical axis.

[0010] Preferably, the thumb self-locking assembly includes a thumb SMA wire pad, a thumb SMA wire, a thumb SMA front fixing block, a thumb SMA rear fixing block, and a thumb SMA wire cover plate. One end of the thumb SMA wire passes through the front guide hole and the rear guide hole of the thumb SMA wire pad by fixing the thumb SMA front fixing block, and then the thumb SMA wire is fixed to the thumb SMA rear fixing block; the front end of the thumb SMA wire pad is fixed to the thumb bottom plate, and the rear end of the thumb SMA wire pad is fixed to the thumb cover plate.

[0011] Preferably, the index finger self-locking assembly, the middle finger self-locking assembly and the ring finger self-locking assembly have the same structure, and the index finger self-locking assembly includes an index finger SMA wire pad, an index finger SMA wire, an index finger SMA rear fixing block, an index finger SMA front fixing block, and an index finger SMA wire cover plate. One end of the index finger SMA wire is fixed to the index finger SMA front fixing block and passes through the front guide hole and the rear guide hole of the SMA wire pad and then fixed to the index finger SMA rear fixing block; the index finger SMA wire pad is fixed to the surface of the cover plate.

[0012] Therefore, the present invention adopts the above-mentioned under-actuated dexterous hand based on tendon cable transmission and SMA locking, uses a single motor to drive multiple fingers, has a compact structure, and reduces overall weight and complexity.

[0013] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the overall structure of an under-actuated dexterous hand based on tendon cable transmission and SMA locking according to the present invention;

[0015] Figure 2 This is a schematic structural diagram of a shell assembly of an under-actuated dexterous hand based on tendon cable transmission and SMA locking according to the present invention;

[0016] Figure 3 This is a schematic structural diagram of a power drive assembly of an under-actuated dexterous hand based on tendon cable transmission and SMA locking according to the present invention;

[0017] Figure 4 This is a schematic structural diagram of a motor assembly of an under-actuated dexterous hand based on tendon cable transmission and SMA locking according to the present invention;

[0018] Figure 5 This is a schematic structural diagram of a thumb assembly of an under-actuated dexterous hand based on tendon cable transmission and SMA locking according to the present invention;

[0019] Figure 6 This is a structural schematic diagram of a thumb self-locking assembly of an under-actuated dexterous hand based on tendon cable transmission and SMA locking according to the present invention;

[0020] Figure 7 This is a schematic structural diagram of an index finger self-locking assembly of an under-actuated dexterous hand based on tendon cable transmission and SMA locking according to the present invention;

[0021] Figure 8 This is a structural schematic diagram of the tendon winding of an under-actuated dexterous hand based on tendon transmission and SMA locking according to the present invention.

[0022] Reference numerals

[0023] 1. Cover plate; 2. Housing assembly; 21. Housing; 22. Redirecting pulley; 201. First redirecting pulley; 202. Second redirecting pulley; 203. Third redirecting pulley; 204. Fourth redirecting pulley; 205. Fifth redirecting pulley; 206. Sixth redirecting pulley; 207. Seventh redirecting pulley; 208. Eighth redirecting pulley; 209. Ninth redirecting pulley; 210. Tenth redirecting pulley; 211. Eleventh redirecting pulley; 212. Twelfth redirecting pulley; 213. Thirteenth redirecting pulley; 214. Fourteenth redirecting pulley; 215. Fifteenth redirecting pulley; 216. Sixteenth redirecting pulley; 21 7. The seventeenth redirecting pulley; 218. The eighteenth redirecting pulley; 219. The nineteenth redirecting pulley; 220. The twentieth redirecting pulley; 221. The twenty-first redirecting pulley; 222. The twenty-second redirecting pulley; 223. The twenty-third redirecting pulley; 224. The twenty-fourth redirecting pulley; 225. The twenty-fifth redirecting pulley; 226. The twenty-sixth redirecting pulley; 227. The twenty-seventh redirecting pulley; 228. The twenty-eighth redirecting pulley; 229. The twenty-ninth redirecting pulley; 230. The thirtieth redirecting pulley; 231. The thirty-first redirecting pulley; 232. The thirty-second redirecting pulley; 233. The thirty-third redirecting pulley Pulley; 234, thirty-fourth redirection pulley; 235, thirty-fifth redirection pulley; 236, thirty-sixth redirection pulley; 237, thirty-seventh redirection pulley; 238, thirty-eighth redirection pulley; 3, power drive assembly; 31, motor body; 311, motor rear cover; 312, motor; 313, flange; 314, reducer; 315, motor front cover; 32, motor cover; 33, disc; 331, front groove; 332, rear groove; 4, four-finger assembly; 41, thumb assembly; 411, bottom plate; 412, guide rail; 413, slider; 414, slider plate; 415, finger body; 4 16. Thumb cover; 417. Side swing motor; 42. Index finger assembly; 43. Middle finger assembly; 44. Ring finger assembly; 5. Tendon rope; 6. Self-locking assembly; 61. Thumb self-locking assembly; 611. Thumb SMA wire; 612. Thumb SMA front fixing block; 613. Thumb SMA rear fixing block; 614. Thumb SMA wire pad; 615. Thumb SMA wire cover; 62. Index finger self-locking assembly; 621. Index finger SMA wire; 622. Index finger SMA rear fixing block; 623. Index finger SMA front fixing block; 624. Index finger SMA wire pad; 625. Index finger SMA wire cover. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0025] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0026] The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0027] Example 1

[0028] like Figure 1-8 As shown, the present invention is an under-actuated dexterous hand based on tendon transmission and SMA locking, including a cover plate 1, a shell assembly 2, a power drive assembly 3, a four-finger assembly 4, a tendon 5 and a self-locking assembly 6. The cover plate 1 is located above the shell assembly 2, and the power drive assembly 3 is provided between the cover plate 1 and the shell assembly 2. A tendon 5 is provided on one side of the power drive assembly 3. The tendon 5 is connected to the four-finger assembly 4 through a redirecting pulley 22. The four-finger assembly 4 is provided with a self-locking assembly 6. The shell assembly 2 includes a shell 21 and a plurality of redirecting pulleys 22 fixed above the shell 21.

[0029] The power drive assembly 3 includes a motor body 31, a motor cover 32 and a disc 33, and the edge of the disc 33 is provided with a front groove and a rear groove; the four-finger assembly includes a thumb assembly 41, an index finger assembly 42, a middle finger assembly 43 and a ring finger assembly 44, and the thumb assembly 41, the index finger assembly 42, the middle finger assembly 43 and the ring finger assembly 44 are all provided with a base plate 411, a guide rail 412, a slider 413, a slider plate 414, a finger body 415 and a thumb cover 416. The base plate 411 of the index finger assembly 42, middle finger assembly 43, and ring finger assembly 44 is integrally manufactured with the housing 21. The base plate 411 of the thumb assembly 41 is connected to the housing 21 via a pivoting pair. A guide rail 412 is provided on the base plate 411. The guide rail 412 is slidably connected to a slider 413. The slider 413 is fixedly connected to a slider plate 414. The finger body 415 is hingedly connected to the slider plate 414. A thumb cover 416 is provided above the finger body 415. The guide rails 412 of the index finger assembly 42, middle finger assembly 43, and ring finger assembly 44 are connected to the housing 21. The thumb assembly 41 is equipped with a side swing motor 417.

[0030] A motor cover 32 is installed on the outside of the motor body 31. The motor body 31 includes a motor rear cover 311, a motor 312, a flange 313, a reducer 314, and a motor front cover 315. The disc 33 is connected to one end of the output shaft of the reducer 314 in the motor body 31. The other end of the output shaft of the reducer 314 is connected to the motor 312 via the flange 313. The other end of the motor 312 is connected to the motor rear cover 311. A motor front cover 315 is installed on the outside of the reducer 314.

[0031] The ends of the tendon 5 are fixed to the front groove 331 and rear groove 332 of the disc 33, respectively. The tendon 5 sequentially passes through several redirecting pulleys 22 to form a closed loop. The thumb assembly 41 is equipped with a sway motor 417. The self-locking assembly 6 includes a thumb self-locking assembly 61, an index finger self-locking assembly 62, a middle finger self-locking assembly, and a ring finger self-locking assembly. The thumb SMA wire 611 in the thumb self-locking assembly 61 is wound and fixed to the thumb SMA wire pad 614. The front end of the thumb SMA wire pad 614 is fixed to the thumb base plate 411, and the rear end of the thumb SMA wire pad is fixed to the thumb cover plate 416. The index finger SMA wire 621 in the index finger self-locking assembly 62 is wound and fixed to the index finger SMA wire pad 624 fixed to the cover plate 1.

[0032] The thumb self-locking assembly 61 includes a thumb SMA wire backing plate 614, a thumb SMA wire 611, a thumb SMA front fixing block 612, a thumb SMA rear fixing block 613, and a thumb SMA wire cover plate 615. One end of the thumb SMA wire 611 passes through the front and rear guide holes of the thumb SMA wire backing plate 614, securing the thumb SMA front fixing block 612 to the thumb SMA rear fixing block 613. The front end of the thumb SMA wire backing plate 614 is secured to the base plate 411, and the rear end of the thumb SMA wire backing plate 614 is secured to the thumb cover plate 416.

[0033] The index finger self-locking assembly 62, the middle finger self-locking assembly, and the ring finger self-locking assembly have the same structure. The index finger self-locking assembly 62 includes an index finger SMA wire backing plate 624, an index finger SMA wire 621, an index finger SMA rear fixing block 622, an index finger SMA front fixing block 623, and an index finger SMA wire cover plate 625. One end of the index finger SMA wire 621 is fixed to the index finger SMA front fixing block 623, passes through the front and rear guide holes of the SMA wire backing plate 624, and then is fixed to the index finger SMA rear fixing block 622. The index finger SMA wire backing plate 624 is fixed to the surface of the cover plate 1.

[0034] The tendon 5 is connected from the rear groove 332 of the disc 33 to the first bend pulley 201, the second bend pulley 202, the third bend pulley 203, and the fourth bend pulley 204, and then passes through the seventh bend pulley 207 fixed to the slider plate 414. The tendon 5 is then passed from the seventh bend pulley 207 to the eleventh bend pulley 211 and the tenth bend pulley 210, and then to the eighth bend pulley 208 fixed to the slider plate 414. After exiting from the eighth bend pulley 208, the tendon 5 passes through the ninth bend pulley 209 and the sixth bend pulley 206 in sequence, and then exits from the upper end of the fifth bend pulley 205, passes through the fourth bend pulley 204, and then enters the twelfth bend pulley 212. The wheel passes through the thirteenth redirecting pulley 213, the fourteenth redirecting pulley 214, and goes around the lower end of the fifteenth redirecting pulley 215, and goes out from its upper end, goes around the seventeenth redirecting pulley 217 fixed to the slider plate 414, the twentieth redirecting pulley 220, the twenty-first redirecting pulley 221, goes around the eighteenth redirecting pulley 218 fixed to the slider plate 414, the nineteenth redirecting pulley 219, the sixteenth redirecting pulley 216, the twenty-second redirecting pulley 222, goes around the lower end of the twenty-third redirecting pulley 223, and goes out from its upper end. The wheel then winds around the 26th redirecting pulley 226 fixed to the slider plate 414, passes through the 29th redirecting pulley 229 and the 28th redirecting pulley 228, and then winds around the 27th redirecting pulley 227, the 25th redirecting pulley 225, the 24th redirecting pulley 224, and the 30th redirecting pulley 230, all fixed to the slider plate 414, and then winds around the lower end of the 37th redirecting pulley 237. It then winds out from the upper end, winds around the 34th redirecting pulley 234 fixed to the slider plate 414, passes through the 35th redirecting pulley 235 and the 32nd redirecting pulley 232, and then winds around the 33rd redirecting pulley 233 fixed to the slider plate 414. It then passes through the 31st redirecting pulley 231, the 36th redirecting pulley 236, and the 38th redirecting pulley 238, and then returns to the front groove 331 of the disc 33.

[0035] With this winding method, when the disc 33 is driven counterclockwise by the motor 312, the force on the thumb's seventh redirecting pulley 207 is unequal to that on the eighth redirecting pulley 208, and the force on the seventh redirecting pulley 207 is greater than that on the eighth redirecting pulley 208, causing the slider plate 414 corresponding to the thumb to move toward the center of the palm. For the index finger, the force on the seventeenth redirecting pulley 217 is unequal to that on the eighteenth redirecting pulley 218, and the force on the seventeenth redirecting pulley 217 is greater than that on the eighteenth redirecting pulley 218, causing the slider plate corresponding to the index finger to move toward the center of the palm. For the middle finger, the force on the twenty-sixth redirecting pulley 226 is unequal to that on the twenty-seventh redirecting pulley 227, and the force on the twenty-sixth redirecting pulley 226 is greater than that on the twenty-sixth redirecting pulley 227, causing the slider plate 414 corresponding to the middle finger to move toward the center of the palm. For the ring finger, the force applied to the thirty-fourth redirecting pulley 234 is unequal to that applied to the thirty-third redirecting pulley 233, and the force applied to the thirty-fourth redirecting pulley 234 is greater than that applied to the thirty-third redirecting pulley 233, causing the slider plate 414 corresponding to the ring finger to move toward the center of the palm. The movement of the slider plate 414 enables the bending of each finger. Similarly, when the disk 33 rotates clockwise, the redirecting pulleys 22 attached to each slider plate 414 are subjected to different forces, causing each slider plate 414 to move away from the center of the palm, corresponding to the relaxation of each finger. As the disk 33 rotates, each slider plate 414 is subjected to the combined force generated by the force difference between the redirecting pulleys 22, causing all slider plates 414 to move toward or away from the center of the palm, enabling a single motor to drive multiple fingers simultaneously.

[0036] During the grasping of complex objects, if a finger first contacts the object and reaches its limit, even though the slider 413 is immobilized, the redirecting pulley 22 on the corresponding slider plate 414 is unaffected and can continue to move. In other words, the tendon 5 can still stably transmit force to the other fingers, allowing them to continue grasping. Similarly, during the release process, if the self-locking function of one finger is triggered, it does not affect the relaxation of the other fingers. This achieves adaptive grasping of complex objects.

[0037] Working Principle: A motor 312 drives the rotation of a disc 33 through a reducer 314. The disc's edge is provided with a front groove 331 and a rear groove 332. Tendons 5 are secured at both ends to the front and rear grooves of the disc 33, forming a closed loop. These tendons pass through multiple redirecting pulleys 22 on the housing 21, transmitting power to the four-finger assembly 4. A single motor, through the tendon 5's designed path, achieves synchronized movement of the thumb, index finger, middle finger, and ring finger. If a finger's contact with an object is blocked, the tension in the tendon 5 is automatically distributed to the other fingers, enabling adaptive grasping.

[0038] Redirection pulley force differential drive: Multiple redirection pulleys 22 are fixed to the slider plate 414 of each finger. The tendon 5 is wound around different redirection pulleys 22 to create a force differential, driving the slider plate 414 to move. Adaptive locking mechanism: Based on the SMA locking principle, the thumb SMA wire 611 and index finger SMA wire 621 contract when heated by electricity, increasing the tension. Their ends are fixed, and the winding path is also fixed. A large normal force is generated between the thumb SMA wire 611 and index finger SMA wire 621 and the thumb SMA wire pad 614 and index finger SMA wire pad 624, which in turn creates a large friction between the SMA wire and the SMA wire pad, thereby achieving self-locking.

[0039] Locking method: Thumb self-locking assembly 61: Thumb SMA wire 611 is wrapped around a thumb SMA wire pad 614 fixed to the slider plate 414. When retracted, it tightens the slider plate 414 and the guide rail 412, preventing sliding. Index finger / middle finger / ring finger self-locking assembly: Thumb SMA wire 611 is wrapped around a thumb SMA wire pad 614 on the cover plate 1. When retracted, it locks the relative position between the slider plate 414 and the cover plate 1. The SMA wire of each finger can be individually energized to achieve locking of specific fingers.

[0040] Grasping stage: The motor 312 drives the disc 33 to rotate counterclockwise, the tendon 5 is tightened, the four-finger slider plate 414 moves toward the palm, and the fingers are bent; Adaptive adjustment: If the thumb touches the object first, the slider plate 414 stops moving, and the tension of the tendon 5 is redistributed to the other fingers through the redirection pulley (207→208→other pulleys), continuing to drive the index finger and middle finger to complete the enveloping grasping; Locking trigger: The thumb SMA wire 611 is energized, contracting and locking the slider plate position to maintain the grasping force.

[0041] Release stage: the motor 312 reverses: the disc 33 rotates clockwise, the tendon rope 5 is tightened, the slider plate 414 is reset, and the fingers are extended; the lock is released: the SMA wire is powered off and cooled, and the original length is restored, and the slider plate 414 is released to slide freely.

[0042] Therefore, the present invention adopts the above-mentioned under-actuated dexterous hand based on tendon transmission and SMA locking, and uses a single motor to drive multiple fingers. It has a compact structure, reduces the overall weight and complexity, and through a reasonable winding layout, a single motor can drive multiple fingers, and the bending and relaxation movements of the fingers can be realized by the forward and reverse rotation of the motor. The self-locking structure is simple and easy to control.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An underactuated dexterous hand based on tendon cable transmission and SMA locking, characterized in that: The utility model comprises a cover plate, a shell assembly, a power drive assembly, a four-finger assembly, a tendon rope and a self-locking assembly. The cover plate is located above the shell assembly. A power drive assembly is provided between the cover plate and the shell assembly. A tendon rope is provided on one side of the power drive assembly. The tendon rope is connected to the four-finger assembly through a redirection pulley. A self-locking assembly is provided in the four-finger assembly. The shell assembly comprises a shell and several redirection pulleys fixed above the shell; the power drive assembly comprises a motor body, a motor cover plate and a disc, and the edge of the disc is provided with a front groove and a rear groove; the four-finger assembly comprises a thumb assembly, The index finger assembly, middle finger assembly and ring finger assembly are each provided with a base plate, a guide rail, a slider, a slider plate, a finger body and a cover plate. The base plate and the housing of the index finger assembly, middle finger assembly and ring finger assembly are designed to be integrally processed. The ends of the tendon rope are respectively fixed to the front groove and the rear groove of the disc. The tendon rope passes through several redirecting pulleys in sequence to form a closed loop path. The thumb assembly is provided with a side swing motor. The self-locking assembly includes a thumb self-locking assembly and an index finger self-locking assembly, a middle finger self-locking assembly and a ring finger self-locking assembly. The thumb self-locking assembly includes a thumb SMA wire pad, a thumb SMA wire, a thumb SMA front fixing block, a thumb SMA rear fixing block, and a thumb SMA wire cover plate. One end of the thumb SMA wire passes through the front guide hole and the rear guide hole of the thumb SMA wire pad plate by fixing the thumb SMA front fixing block, and then the thumb SMA wire is fixed to the thumb SMA rear fixing block; the front end of the thumb SMA wire pad is fixed to the thumb bottom plate, and the rear end of the thumb SMA wire pad is fixed to the thumb cover plate.

2. The underactuated dexterous hand based on tendon cable transmission and SMA locking according to claim 1, characterized in that: A motor cover is provided on the outside of the motor body, and the motor body includes a motor back cover, a motor, a flange, a reducer and a motor front cover; the disc is connected to one end of the output shaft of the reducer in the motor body, the other end of the output shaft of the reducer is connected to the motor through a flange, the other end of the motor is connected to the motor back cover, and a motor front cover is provided on the outside of the reducer.

3. The underactuated dexterous hand based on tendon cable transmission and SMA locking according to claim 1, characterized in that: The base plate in the thumb assembly is connected to the shell through a rotating pair, and a guide rail is provided on the base plate. The guide rail and the slider are slidably connected, and the slider and the slider plate are fixedly connected. The finger body is connected to the slider plate through a hinge, and a thumb cover is provided above the finger body. The guide rails in the index finger assembly, the middle finger assembly and the ring finger assembly are connected to the shell.

4. The underactuated dexterous hand based on tendon cable transmission and SMA locking according to claim 1, characterized in that: The thumb assembly is provided with a side swing motor, which directly drives the thumb base plate to rotate around the vertical axis.

5. The underactuated dexterous hand based on tendon cable transmission and SMA locking according to claim 1, characterized in that: The index finger self-locking assembly, middle finger self-locking assembly and ring finger self-locking assembly have the same structure. The index finger self-locking assembly includes an index finger SMA wire pad, an index finger SMA wire, an index finger SMA rear fixing block, an index finger SMA front fixing block, and an index finger SMA wire cover plate. One end of the index finger SMA wire is fixed to the index finger SMA front fixing block and passes through the front guide hole and the rear guide hole of the SMA wire pad plate and then fixed to the index finger SMA rear fixing block; the index finger SMA wire pad is fixed to the surface of the cover plate.

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