A drive link and rope fused variable coupling adaptive prosthetic finger

Abstract

A kind of drive link and rope fusion variable coupling adaptive artificial fingers involves the field of artificial limb of limb residual patients.The artificial finger is composed of drive link and rope mechanism, and the micro motor in the drive link mechanism directly drives the proximal phalanx drive link after gear reduction, as the power source of the whole artificial finger movement;The coupling rope in the rope mechanism is connected with the transmission link after winding around the rope cam.The device comprehensively utilizes the advantages of link transmission structure, such as good rigidity, stable energy transmission and large fingertip gripping force, and the advantages of rope transmission structure, such as light weight, suitable for long distance driving and strong flexibility, so that the artificial finger can fit the human hand to make variable coupling adaptive gripping movement, and the artificial finger's anthropomorphism and gripping space range are improved.Sensors are installed on the surface of the proximal phalanx and the distal phalanx, and form a closed loop control with the micro motor to ensure the stability of gripping objects.The overall structure of the artificial finger is light in weight, large in fingertip gripping force, and stable and reliable in transmission.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of artificial limbs for patients with limb disability, and particularly relates to a variable coupling self-adaptive artificial finger with driving connecting rods and ropes fused. BACKGROUND

[0002] An artificial hand is mounted on the end of a residual limb of a patient with limb disability, and is mainly used for grasping objects and moving in space, providing convenience for daily life of people with upper limb loss. It is an important research direction in the field of human rehabilitation engineering. In the existing artificial hand structure, under-actuated mechanism refers to the number of drives being less than the degrees of freedom of the mechanism, which saves some driving elements and can basically meet the requirements of full drive, while reducing the weight and saving energy consumption. Therefore, it has great superiority in the application of artificial hand, and at present, such mechanism has become one of the main directions of artificial finger design. Under-actuated mechanism has multiple transmission forms such as connecting rod, rope, synchronous belt and gear, among which connecting rod transmission and rope transmission are the most widely used.

[0003] In the connecting rod transmission type artificial hand, the nine connecting rod artificial hand designed by Jiang Li team of Harbin Institute of Technology is the most representative. The main structure is composed of a coupling four-bar mechanism and a coupling self-adaptive seven-bar mechanism. The coupling four-bar mechanism makes the proximal phalanx and the middle phalanx fit the coupling motion of the human hand, and the coupling self-adaptive seven-bar mechanism makes the middle phalanx and the distal phalanx fit the coupling motion of the human hand. When the proximal phalanx hits the object, the middle phalanx and the distal phalanx can continue to move under the drive of the motor until all the phalanges are in contact with the object. The connecting rod transmission structure has the advantages of good rigidity, stable energy transmission and large fingertip grasping force, and has attracted the attention of many research teams at home and abroad. However, the pure connecting rod transmission type artificial hand has the problems of fixed transmission ratio, large weight and large volume, which brings great inconvenience to the daily life of patients with limb disability.

[0004] In the rope transmission type artificial hand, ropes are used to realize the coupling motion of phalanges and self-adaptive envelope grasping. The common structure is that ropes are wound on the front and back of the fingers respectively, and the two ropes pass through the three phalanges in turn and are fixed at the top of the fingertips. When the winding wheel rotates counterclockwise under the drive of the motor, the fingers bend under the pull of the ropes. When the winding wheel rotates clockwise, the fingers stretch under the pull of the ropes. Compared with the connecting rod transmission structure, the rope transmission structure has the advantages of simple structure, light weight, suitable for long distance driving and strong flexibility. The Shadow hand of the United Kingdom and the Gifu II hand developed by Gifu University in Japan also use rope transmission. However, the pure rope transmission type artificial hand has the problems of poor rigidity, easy relaxation of ropes, poor stability and small fingertip grasping force, which leads to unstable grasping of the artificial hand, high maintenance rate and short service life.

[0005] In recent years, some researches have proposed to integrate link and rope structures to comprehensively utilize the advantages of link transmission and rope transmission mechanism. For example, patent CN212650954U Artificial Hand Improving the Stability of Gripping Action discloses a finger structure integrating rope driving and coupled four-link, which is different from the traditional way of directly fixing the rope on the fingertip or finger driving device, and can realize motion force amplification by means of the "moving pulley" principle. Patent CN209827112U Driving Rope and Four-Link Mechanism Combination Type Under-actuated Bionic Prosthetic Finger also discloses a finger composed of a four-link structure, a metacarpophalangeal joint using a rope-driven prosthetic structure, which rotates the proximal phalanx by pulling the rope to realize the overall bending of the finger. However, most of the existing rod and rope integrated transmission structures use ropes as the driving force, and the link structure only plays a coupling role for the phalange, which leads to a large room for improvement in the rigidity, energy transmission efficiency and fingertip gripping force of the prosthetic hand. In addition, the i-limb hand of Touch Bionics company also proposes a rod and rope integrated structure driven by a single rod. When the proximal phalanx encounters an object, the finger cannot continue to move, and cannot realize adaptive enveloping gripping of the object. SUMMARY

[0006] The present application aims to overcome the shortcomings of current prosthetic hand products and patent technologies, and provides a variable coupling adaptive prosthetic finger integrating driving link and rope. The device is composed of a driving link mechanism and a rope mechanism, which fully utilizes the advantages of good rigidity, stable energy transmission and large fingertip gripping force of the link transmission structure, as well as the advantages of light weight and strong flexibility of the rope transmission structure, so that the prosthetic finger can fit the human hand to perform variable coupling adaptive under-actuated gripping motion. In addition, the sensor installed on the surface of the finger is used for feedback control of the motor, which ensures the stability of the gripping action.

[0007] The present application adopts the following technical solutions:

[0008] The variable coupling adaptive prosthetic finger integrating driving link and rope includes a base, a micro motor, a small spur gear, a large spur gear, a proximal phalanx and a distal phalanx. The micro motor is fixedly connected with the base, the output shaft of the micro motor is connected with the small spur gear through a key, the small spur gear and the large spur gear are engaged, the large spur gear is connected with the proximal joint shaft through a key, the proximal phalanx is installed on the base through the proximal joint shaft, the distal phalanx is rotatably connected with the proximal phalanx through the distal joint shaft, and the axes of the proximal joint shaft and the distal joint shaft are parallel to each other.

[0009] The driving link and rope integrated variable coupling adaptive prosthetic finger driving link mechanism further comprises a proximal phalanx driving link, a first transmission link, a proximal phalanx execution link, a distal phalanx link, a proximal joint shaft, a first link shaft, a second link shaft, a distal joint shaft and a sensor. One end of the proximal phalanx driving link is fixedly connected with the proximal joint shaft, and the other end is rotatably connected with one end of the first transmission link through the first link shaft. The other end of the first transmission link is rotatably connected with one end of the distal phalanx link through the second link shaft. The other end of the distal phalanx link is rotatably connected with one end of the proximal phalanx execution link through the distal joint shaft. The other end of the proximal phalanx execution link is rotatably connected with the proximal joint shaft.

[0010] The number of the proximal phalanx driving link, the first transmission link, the distal phalanx link, the proximal phalanx execution link, the first link shaft and the second link shaft is two, which are symmetrically distributed in space with respect to the center section of the finger.

[0011] The driving link and rope integrated variable coupling adaptive prosthetic finger rope mechanism comprises a cam rotating shaft, a rope winding cam, a reset torsion spring, a coupling rope, a reversing wheel shaft, a rope guide shaft and a second link shaft. The cam rotating shaft is installed on a base. The reset torsion spring is coaxially connected with the cam rotating shaft. The cam rotating shaft is fixedly connected with the rope winding cam. The reversing wheel shaft and the rope guide shaft are both installed on the base. One end of the coupling rope is wound on the rope winding cam. The coupling rope is wound around the reversing wheel shaft and the rope guide shaft, and the other end of the coupling rope is fixedly connected with a through hole of the second link shaft, which is located at the center section of the second link shaft.

[0012] The coupling ratio of the movement speed of the proximal phalanx and the distal phalanx is determined by the length of the coupling rope, which changes with the rotation of the rope winding cam. When the prosthetic finger starts to move from the initial state, the coupling ratio is 0.8, that is, During the bending and gripping process, under the tension of the first transmission link, the coupling rope gradually loosens from the rope winding cam and becomes longer, so that the coupling ratio of the movement speed of the proximal phalanx and the distal phalanx increases. When the rope winding cam rotates by 270°, the coupling ratio becomes 1.1. When the prosthetic finger grips the curved object to the final state, the rope winding cam rotates by 360°, and the coupling ratio of the proximal phalanx and the distal phalanx is 1.2.

[0013] The micro motor is a direct current motor. The surface of the proximal phalanx and the distal phalanx contacting the object is provided with a sensor.

[0014] The technical advantages and technical effects of the present application are embodied in:

[0015] The present application adopts a rod and rope fusion transmission structure, a micro motor directly drives a proximal phalanx driving link after gear reduction, as a power source of the whole prosthetic finger movement, and a rope structure is used as a coupling mechanism of the proximal phalanx and the distal phalanx, which has the advantages of good rigidity, stable energy transmission and large fingertip gripping force of the link transmission structure, and the advantages of light weight and strong flexibility of the rope transmission structure.

[0016] In the present application, a winding rope cam and a coupling rope mechanism are designed to realize the coupling movement of the proximal phalanx and the distal phalanx. In the process of bending and gripping of the prosthetic finger, the coupling rope is unwound from the winding rope cam and becomes longer with the bending movement of the finger, thereby changing the coupling ratio of the proximal phalanx and the distal phalanx, so that the prosthetic finger fits the human hand to make a variable coupling gripping movement, and the anthropomorphism and gripping space range of the prosthetic hand are improved.

[0017] In the present application, sensors are installed on the surfaces of the proximal phalanx and the distal phalanx for detecting the contact condition of the prosthetic hand with the grasped object and the stability judgment in the gripping movement. When the sensor data fluctuation value exceeds the set value, the micro motor dynamically adjusts the output torque, thereby adjusting the gripping force of the prosthetic hand, so that the prosthetic hand always maintains stable gripping. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 Mechanism diagram of the present application

[0019] Figure 2 Mechanism diagram of the present application

[0020] Figure 3 Mechanism diagram of the present application

[0021] Figure 4 Front view of the present application

[0022] Figure 5 Coupling ratio change diagram of the proximal phalanx and the distal phalanx of the present application

[0023] Figure 6 Schematic diagram of the empty hand gripping process of the present application

[0024] Figure 7 Schematic diagram of the envelope gripping process of the present application

[0025] Figure 8 Schematic diagram of the pinch gripping process of the present application

[0026] Figure 9 Schematic diagram of the object releasing process of the present application

[0027] Figures 1-9 In the present application, the corresponding relationship between each number and component is as follows:

[0028] 1. Base 2. Cam shaft 3. Reset torsion spring 4. Rope winding cam 5. Coupling rope 6. Micro motor 7. Small spur gear 8. Large spur gear 9. Proximal joint shaft 10. Proximal phalanx driving link 11. First link shaft 12. First transmission link 13. Distal phalanx link 14. Distal joint shaft 15. Second link shaft 16. Distal phalanx 17. Proximal phalanx 18. Proximal phalanx execution link 19. Reversing wheel shaft 20. Rope guide shaft 21. Sensor 22. Object DETAILED DESCRIPTION

[0029] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings and examples.

[0030] As Figure 1 shown is the mechanism principle diagram of the present application, which mainly includes a driving link mechanism and a rope mechanism. The driving link mechanism is directly driven by the micro motor 6 through gear reduction to realize the self-adaptive under-actuated movement of the prosthetic hand finger. The rope mechanism is connected with the link mechanism after being wound on the rope winding cam 4 by the coupling rope 5, so that the proximal phalanx 17 and the distal phalanx 16 make the variable coupling movement like the human hand.

[0031] The specific structure mechanism diagram, overall mechanism diagram and front view of the embodiment of the variable coupling self-adaptive prosthetic hand finger of the driving link and rope fusion are shown in Figure 2 , Figure 3 and Figure 4 respectively. The driving link mechanism of the embodiment includes the base 1, the micro motor 6, the small spur gear 7, the large spur gear 8, the proximal phalanx 17 and the distal phalanx 16. The micro motor 6 is fixedly connected with the base 1, the output shaft of the micro motor 6 is connected with the small spur gear 7 through a key, the small spur gear 7 and the large spur gear 8 are engaged, and the large spur gear 8 is connected with the proximal joint shaft 9 through a key. The proximal phalanx 17 is installed on the base 1 through the proximal joint shaft 9, the distal phalanx 16 is rotationally connected with the proximal phalanx 17 through the distal joint shaft 14, and the axes of the proximal joint shaft 9 and the distal joint shaft 14 are parallel to each other.

[0032] In the embodiment, the driving link mechanism further includes the proximal phalanx driving link 10, the first transmission link 12, the proximal phalanx execution link, the distal phalanx link 13, the proximal joint shaft 9, the first link shaft 11, the second link shaft 15, the distal joint shaft 14 and the sensor. One end of the proximal phalanx driving link 10 is fixedly connected with the proximal joint shaft 9, the other end is rotationally connected with one end of the first transmission link 12 through the first link shaft 11, the other end of the first transmission link 12 is rotationally connected with one end of the distal phalanx link 13 through the second link shaft 15, the other end of the distal phalanx link 13 is rotationally connected with one end of the proximal phalanx execution link 18 through the distal joint shaft 14, and the other end of the proximal phalanx execution link 18 is rotationally connected with the proximal joint shaft 9.

[0033] In this embodiment, the number of proximal phalange driving link 10, first transmission link 12, distal phalange link 13, proximal phalange execution link, first link shaft 11 and second link shaft 15 is two, which are symmetrically distributed in space about the center section of the finger.

[0034] In this embodiment, the rope mechanism of the prosthetic finger includes cam rotating shaft 2, winding rope cam 4, reset torsion spring 3, coupling rope 5, reversing wheel shaft 19, rope guide shaft 20 and second link shaft 15. The cam rotating shaft 2 is installed on the base 1, the reset torsion spring 3 is coaxially connected with the cam rotating shaft 2, the cam rotating shaft 2 is fixedly connected with the winding rope cam 4, the reversing wheel shaft 19 and the rope guide shaft 20 are both installed on the base 1, one end of the coupling rope 5 is wound on the winding rope cam 4, the middle part passes through the reversing wheel shaft 19, then passes through the rope guide shaft 20, and the other end is finally fixed on the through hole of the second link shaft 15, which is located at the center section of the second link shaft 15.

[0035] In this embodiment, the coupling ratio of the movement speed of the proximal phalange 17 and the distal phalange 16 is determined by the length of the coupling rope 5, which changes constantly with the rotation of the winding rope cam 4, and the relationship is as shown in the following formula: Figure 5 When the prosthetic finger starts to move from the initial state, the coupling ratio is 0.8, that is, In the bending and gripping process, under the tension of the first transmission link 12, the coupling rope 5 is gradually unwound from the winding rope cam 4 and becomes longer, so that the coupling ratio of the movement speed of the proximal phalange 17 and the distal phalange 16 increases, and when the winding rope cam 4 rotates by 270°, the coupling ratio becomes 1.1; when the prosthetic finger grips the object and bends to the final state, the winding rope cam 4 rotates by 360°, and the coupling ratio of the proximal phalange 17 and the distal phalange 16 is 1.2.

[0036] In this embodiment, the micro motor 6 is a DC servo motor, and the surface of the proximal phalange 17 and the distal phalange 16 contacting the object is provided with a sensor 21.

[0037] The embodiment of the variable coupling self-adaptive prosthetic finger driven by the link and the rope according to the present application is described as follows in combination with the specific object gripping process: Figure 6 、 Figure 7 、 Figure 8 and Figure 9

[0038] In this embodiment, the initial state is the straight state, as shown in the following figure: Figure 6 ​As shown in Figure 1 on the left, when the fingers begin to grasp, the micro motor 6 rotates forward, and after gear reduction, drives the proximal phalanx drive link 10. The proximal phalanx drive link 10, via the first link shaft 11 and the second link shaft 15, sequentially drives the first transmission link 12 and the distal phalanx link 13. The proximal phalanx actuator link bends inward under the action of the proximal joint shaft 9 and the distal joint shaft 14. One end of the coupling rope 5 is fixed to the proximal joint shaft 9. When the proximal joint shaft 9 rotates, it pulls the rope-winding cam 4 to rotate together, thereby "unwinding" the coupling rope 5 wrapped on the rope-winding cam 4. Under the action of the coupling rope 5, the distal phalanx 16 rotates together with the proximal phalanx 17 in a certain proportion, bending inward and forming a "fist" state. Figure 6 As shown, when the fingers do not touch an object during the grasping motion, the proximal phalanx 17 and distal phalanx 16 begin to move from a vertical position until they finally reach a "clenched" state, as... Figure 6 As shown in right 1.

[0039] In this embodiment, when the proximal phalanx 17 touches the object first, such as Figure 7 As shown, this represents the state of enveloping and grasping an object. When the proximal phalanx 17 contacts the object, the proximal phalanx actuator stops rotating, meaning the proximal phalanx 17 ceases to move. Since the coupling rope 5 continues to lengthen with the rotation of the rope-wrapping cam 4, the distal phalanx 16 can continue to move. The micro motor 6 continues to drive the proximal phalanx actuator linkage 10 to rotate, which, after passing through the first transmission linkage 12, drives the distal phalanx linkage 13 to continue bending inward until the distal phalanx 16 also contacts the object. Figure 6 As shown in right 1, an envelope grasp is formed.

[0040] In this embodiment, when the distal phalanx 16 touches the object first, such as Figure 8 As shown, this is the state of pinching an object; when the distal phalanx 16 contacts the object, the distal phalanx linkage 13 stops rotating, and the proximal phalanx drive linkage 10 is restricted to rotate via the second drive shaft, the first drive linkage 12, the first drive shaft and the coupling rope 5, thereby restricting the proximal phalanx 17 from continuing to rotate.

[0041] In this embodiment, after the prosthetic finger completes the envelope grasp or pinching of the object, the sensors on the surface of the proximal phalanx 17 and distal phalanx 16 detect the stability of the object. When the sensor detects that the object is shaking, it sends a signal to the micro motor 6. The micro motor 6 increases the output torque, thereby increasing the gripping force of the prosthetic finger and restoring the object to a stable state.

[0042] In this embodiment, when the prosthetic finger releases its grip on the object, such as Figure 9As shown, the micro motor 6 reverses, drives the proximal phalange driving link 10 to reverse through the large gear and the small gear deceleration, the proximal phalange driving link 10 drives the first transmission link 12 to reverse, the first transmission link 12 drives the distal phalange link 13 to reverse, so that the distal phalange 16 is stretched, and the proximal phalange 17 is loosened under the drive of the proximal joint shaft 9 and the distal joint shaft 14, and the object is released, such as Figure 8 As shown in the left 2; at the same time, the reset torsion spring 3 contracts, drives the cam shaft 2 to reverse, and makes the coupling rope 5 wind around the rope winding cam 4. In turn, continue to move until the proximal phalange 17 and the distal phalange 16 are restored to the straight state.

Claims

1. A variable coupling adaptive prosthetic finger with integrated drive linkage and rope, comprising a drive linkage mechanism and a rope mechanism, wherein the drive linkage mechanism comprises a base (1), a micro motor (6), a small spur gear (7), a large spur gear (8), a proximal phalanx (17), and a distal phalanx (16); the rope mechanism comprises a cam shaft (2), a rope-winding cam (4), a return torsion spring (3), a coupling rope (5), a reversing wheel shaft (19), a rope guide shaft (20), and a second linkage shaft (15); The drive linkage mechanism specifically includes a proximal phalanx drive linkage (10), a first transmission linkage (12), a proximal phalanx actuation linkage (18), a distal phalanx linkage (13), a proximal joint shaft (9), a first linkage shaft (11), a second linkage shaft (15), a distal joint shaft (14), and a sensor (21). Its features are: The micro motor (6) is fixedly connected to the base (1). The output shaft of the micro motor (6) is connected to the small spur gear (7) by a key. The small spur gear (7) and the large spur gear (8) mesh with each other. The large spur gear (8) is connected to the proximal joint shaft (9) by a key. The proximal phalanx (17) is mounted on the base through the proximal joint shaft (9). The distal phalanx (16) is rotatably connected to the proximal phalanx (17) through the distal joint shaft (14). The axes of the proximal joint shaft (9) and the distal joint shaft (14) are parallel to each other. One end of the proximal phalanx drive link (10) is fixedly connected to the proximal joint shaft (9), and the other end is rotatably connected to one end of the first transmission link (12) through the first link shaft (11). The other end of the first transmission link (12) is rotatably connected to one end of the distal phalanx link (13) through the second link shaft (15). The other end of the distal phalanx link (13) is rotatably connected to one end of the proximal phalanx execution link (18) through the distal joint shaft (14). The other end of the proximal phalanx execution link (18) is rotatably connected to the proximal joint shaft (9). The number of the proximal phalanx drive link (10), the first transmission link (12), the distal phalanx link (13), the proximal phalanx actuation link (18), the first link shaft (11), and the second link shaft (15) are all two, and they are symmetrically distributed in space about the central cross section of the finger. The rope mechanism is characterized in that: the cam shaft (2) is mounted on the base (1), the reset torsion spring (3) is coaxially connected to the cam shaft (2), the cam shaft (2) is fixedly connected to the rope winding cam (4), the reversing wheel shaft (19) and the rope guide shaft (20) are both mounted on the base (1), one end of the coupling rope (5) is wound around the rope winding cam (4), passes around the reversing wheel shaft (19) in the middle, passes around the rope guide shaft (20) again, and finally the other end is fixed to the through hole of the second connecting rod shaft (15), the through hole is located at the center section of the second connecting rod shaft (15).

2. The variable-coupling adaptive prosthetic finger with integrated drive linkage and rope as described in claim 1, characterized in that: The coupling ratio of the movement speeds of the proximal phalanx (17) and distal phalanx (16) is determined by the length of the coupling rope (5), which changes continuously as the rope-wrapping cam (4) rotates; the coupling ratio is 0.8 when the prosthetic finger begins to move from its initial state. During the bending and gripping process, under the pulling force of the first transmission link (12), the coupling rope (5) gradually loosens from the rope cam (4) and becomes longer, which increases the coupling ratio of the movement speed of the proximal phalanx (17) and the distal phalanx (16). When the rope cam (4) rotates 270°, the coupling ratio becomes 1.

1. When the prosthetic finger is bent to the final state with a bare hand grip, the rope cam (4) rotates 360°, and the coupling ratio of the proximal phalanx (17) and the distal phalanx (16) is 1.2.

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