CN103690280B - Continuum transmission mechanism-based under-actuated prosthetic hand - Google Patents

Abstract

The invention discloses an underactuated prosthetic hand based on a continuum transmission mechanism. The prosthetic hand includes a motor drive unit, a continuum transmission mechanism and a manipulator, wherein the continuum transmission mechanism includes a fixed plate, multiple fixed tubes, and multiple guide tubes , a base, a plurality of driven wires, a spacer disc and a locking disc; the motor drive unit includes a motor, an output mechanism and a plurality of drive wires; and the manipulator includes a palm and five fingers, each finger has a plurality of knuckles; the motor The rotation of the driving wire can be converted into the linear motion of the driving wire through the output mechanism, and the linear motion of the driving wire can drive the continuous body transmission mechanism to deform, so that the driven wire fixed at one end and the locking disc moves, thereby driving each finger of the manipulator to complete the corresponding action . The invention does not use traditional rigid kinematic pairs such as hinges and connecting rods, which effectively eliminates the hysteresis of the system and reduces the weight of the prosthetic hand. The use of a large number of elastic alloy wires makes the prosthetic hand have a strong self-adaptive ability.

Description

Underactuated prosthetic hand based on continuum transmission mechanism

technical field

The invention relates to the technical field of medical instruments, in particular to a medical prosthetic hand system.

Background technique

Due to accidents, industrial injuries, diseases and other reasons, there are a large number of amputee patients in the world, most of whom are hand amputee patients. They cannot independently complete daily life needs, so the quality of life is significantly reduced. In order to improve the quality of life of people with hand amputations, related companies and scientific research institutions have developed a variety of prosthetics, including widely used single-free prosthetic hands and multi-free prosthetic hands with humanoid shapes.

The single-free prosthetic hand can complete limited grasping actions through simple finger opening and closing. It has a single function, poor practicability, and does not have a humanoid shape. After wearing it, it is not harmonious with the human body and is easily rejected by patients; multiple degrees of freedom The prosthetic hand has the appearance of a human hand, is easily accepted by patients, and has a similar number of joints to the human hand, so it has better flexibility and can achieve a variety of actions. However, this multi-freedom prosthetic hand uses more hinges, Connecting rods or other traditional transmission methods have complex structures and high costs, and have not been widely used yet.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to: use less input to control the output of the multi-degree-of-freedom of the prosthetic hand; simultaneously avoid the use of complex kinematic pairs such as hinges and connecting rods to reduce the weight of the prosthetic hand and reduce costs .

In order to achieve the above purpose, the present invention provides a new type of underactuated prosthetic hand, which uses less motors as the driving input, and specially designs a flexible transmission mechanism, which can completely connect the driving input and driving output components. For a continuum with continuously variable elastic deformation, under a suitable driving input, the continuum mechanism can output more (more than the number of driving inputs) motion output through its overall continuous deformation. The various motion outputs produced by the transmission of the continuum mechanism are different, but they have a reasonable mathematical relationship with each other. Use various motion outputs to realize the rotation of each joint of the prosthetic hand, so that the humanoid prosthetic hand can achieve flexible and coordinated movements. Since traditional rigid kinematic pairs such as hinges and connecting rods are not used in the mechanism, the hysteresis of the system is eliminated. A large number of elastic alloy wires are used as the driving and transmission elements, so that the prosthetic hand has a strong adaptive ability, and at the same time, the weight of the prosthetic hand is significantly reduced. The system adopts less driving input, realizes more motion output, has simple structure, and obviously reduces cost. At the same time, the various movements are coordinated with each other, so that the joints of the fingers have a coordinated movement relationship, so that the prosthetic hand can complete more coordinated movements that are closer to the human hand.

Technical scheme of the present invention is as follows:

The present invention is mainly composed of three parts, including a motor drive unit, a continuum transmission mechanism and an adaptive prosthetic hand with a humanoid shape, and each part will be described in detail below. Motor drive unit: The motor drive unit consists of two similar parts, fixed on the same base. Each part includes a motor fixed on the base plate, and an output gear is fixed on the output shaft of the motor. At the same time, there are two racks on both sides of the output gear, which are respectively connected to the base plate through linear guide rails. The racks are both meshed with the middle gear. When the gears rotate, the two racks move in different directions. An elastic alloy wire is respectively fixed on each rack. When the motor rotates, the elastic alloy wire will make a linear push-pull motion. The two elastic alloy wires driven by the same motor move in opposite directions, but the movement distance is the same. Two motors are arranged side by side to drive four elastic alloy wires, and the elastic alloy wires are connected to the continuum mechanism through a fixed metal tube as the motion input of the continuum mechanism. Continuum transmission mechanism for motion coordination: This mechanism is used to realize the underactuated motion of the prosthetic hand, and convert the independent motion input of two pairs of elastic alloy wires into the coordinated motion output of six elastic alloy wires. The mechanism is composed of a base, a spacer disc, a locking disc, a spring and an elastic alloy wire. There are through holes at the same position on the base and the spacer, which can respectively pass through the driving wire and the driven wire, and then use the locking disc to lock and fix all the elastic alloy wires. There are springs between them, which are worn on the elastic alloy wire to keep the distance between the discs. In the initial state, the shape of the continuum mechanism is straight. When the two-way driving input pushes and pulls the four driving wires, the continuum mechanism forms an arc-shaped bend, and the output wires also passively form a corresponding shape. Since each output wire is fixed at a different position on the locking disc, the output wire is elongated. The length of shortening varies. By using the output wire to drive each joint of the prosthetic hand, different degrees of bending of each finger can be formed. Adaptive prosthetic hand with human-like shape: This prosthetic hand is built to resemble the size of a human hand, has a similar appearance and size to a human hand, and can achieve similar movements to a human hand. It is mainly composed of the palm and five fingers, and the five fingers are respectively fixed at corresponding positions on the palm. Similar to the human hand, the thumb has four degrees of freedom, driven by two elastic alloy wires, one of which is fixed on the tip of the thumb, passes through the second knuckle of the thumb and the third knuckle of the thumb, and then extends to the outside to achieve large The flex of the thumb. Another elastic alloy wire is fixed on the fourth knuckle, passes through the thumb fixing base and the palm, and extends out of the prosthetic hand to realize the lateral swing of the thumb. According to the characteristics of the human hand, the index finger, middle finger, ring finger and little finger have some differences in size, but have the same structural form, and all have three degrees of freedom. Each finger is driven by an elastic metal wire. One end of the metal wire is fixed on the fingertip, and the other end passes through the second and third knuckles, the base of the finger and the palm, and then extends out of the prosthetic hand. Pushing or pulling the elastic alloy wire outside can realize the tightening or unfolding of the corresponding fingers. In order to more closely realize the movement function similar to that of the human hand, torsion springs are installed between the fingers of each joint to keep the joints of the fingers in an unfolded state.

The overall working principle of the present invention is as follows. When the program controls the motor to rotate at different angles, a pair of elastic alloy wires driven by the same motor can push and pull back and forth in opposite directions and at equal distances through rack and pinion transmission. Two pairs of elastic alloy wires extend to the continuum mechanism as the driving input of the continuum transmission mechanism. Due to the push-pull movement of the two pairs of driving elastic alloys, the continuum is bent into an arc shape in a certain direction, and the driven wire parallel to the driving wire fixed on the locking disc is passively bent into a corresponding shape, so that the driven wire also Create a push-pull motion. Six slave wires extend to the continuous body to drive the five fingers of the humanoid prosthetic hand, so that each finger of the prosthetic hand can be bent or unfolded, so as to realize the function of grasping or manipulating objects.

An underactuated prosthetic hand based on a continuum transmission mechanism, the prosthetic hand includes a motor drive unit, a continuum transmission mechanism and a manipulator, wherein the continuum transmission mechanism includes a fixed plate, a plurality of fixed tubes, a plurality of guide tubes, a base seat, multiple driven wires, spacer discs and locking discs, one end of the fixing tube and guide tube is connected to the base, the other end of the fixing tube is connected to the fixing plate, one end of the driven wire is fixed on the locking disc, and the other end One end passes through the spacer disc, the base, the guide tube and the fixed plate in sequence and is finally connected to the finger of the manipulator; the motor drive unit includes a motor, an output mechanism and multiple driving wires, one end of the driving wire is fixed on the output mechanism, and the other end is sequentially Pass through the fixed plate, the fixed tube, the base and the spacer plate, and be fastened to the locking plate; and the manipulator includes the palm and five fingers, each finger has a plurality of knuckles, and there can be space between two adjacent knuckles. Rotationally connected; wherein, the rotation of the motor of the motor drive unit can be converted into the linear motion of the driving wire through the output mechanism, and the linear motion of the driving wire can drive the deformation of the continuum transmission mechanism, so that one end is connected with the locking disc of the continuum transmission mechanism The fixed driven wire moves to drive each finger of the manipulator to complete the corresponding action.

Preferably, the output mechanism includes a base plate, an output gear, a rack, a guide rail and a chute. The output gear is fixedly connected to the output shaft of the motor, and two racks are meshed on both sides of each output gear in parallel, and each tooth The bar is fixed on the guide rail, the size of the guide rail matches the size of the chute fixed on the base plate and can slide along the chute, and the driving wire is fixedly connected with the rack.

Preferably, the motor drive unit includes two motors and two output gears, and the two motors drive four driving wires in total via the two output gears and the rack.

Preferably, the base, the fixing plate, the spacer disc and the locking disc all have small holes for the driving wire and the driven wire to pass through, and the distribution of the small holes is set according to the action of the manipulator to be realized.

Preferably, the fixing tube is arranged between the fixing plate and the corresponding small hole for the driving wire to pass through on the base, one end of the guide tube is fixed on the small hole of the base, and the other end passes through the fixing plate and extends to the manipulator.

Preferably, several driving wires and/or driven wires passing between adjacent bases, spacers and locking plates are covered with springs, so that a certain distance is maintained between the bases, spacers and locking plates. distance.

Preferably, the five fingers include a thumb, and the thumb includes a fingertip, a second knuckle, a third knuckle, a fourth knuckle and a fixed base, and the fixed base is fixed on the palm by screws, and the continuum transmission mechanism A driven wire passes through the fourth knuckle, third knuckle and second knuckle of the thumb and is fixed on the fingertip of the thumb. The pushing and pulling movement of this driven wire can realize the flexion or extension of the thumb; Another driven wire of the continuum transmission mechanism passes through the palm and the fixed base and is fixed on the fourth knuckle of the thumb. The push-pull movement of this driven wire can realize the abduction or adduction of the thumb.

Preferably, five fingers include index finger, middle finger, ring finger and little finger, index finger, middle finger, ring finger and little finger have similar structure, wherein each finger includes fingertip, second knuckle, third knuckle and finger base, finger The base is fixed on the palm of the hand by screws, and the four driven wires of the continuum transmission mechanism respectively pass through the palm and the finger base, the third knuckle and the second knuckle of the corresponding finger and are fixed on the fingertip of the corresponding finger. The push-pull movement of the driven wire can respectively realize the bending or stretching of the index finger, middle finger, ring finger and little finger.

Preferably, two adjacent knuckles are connected by a rotating pin to form a rotatable joint, and a torsion spring is provided at the joint, so that when the driven wire does not pull the finger to move, the finger can maintain a stretched and straight state.

Preferably, the driving wire and the driven wire are made of high-elastic nickel-titanium alloy wire, the fixing tube is made of metal material, and the guide tube is made of polytetrafluoroethylene material.

Description of drawings

Fig. 1 is the schematic diagram of the three-dimensional structure of the underactuated prosthetic hand based on the continuum transmission mechanism of the present invention;

Fig. 2 is the schematic diagram of the three-dimensional structure of the motor drive unit of the prosthetic hand in Fig. 1;

Fig. 3A is a schematic diagram of the continuum transmission mechanism of the prosthetic hand in Fig. 1;

Fig. 3B is a schematic diagram of the continuum part of the continuum transmission mechanism in Fig. 3A being bent in a certain direction to form an arc;

Fig. 4A is a schematic diagram of the manipulator of the prosthetic hand in Fig. 1;

Figure 4B is a schematic diagram of the thumb structure of the manipulator in Figure 4A; and

FIG. 4C is a schematic diagram of the structure of the index finger of the manipulator in FIG. 4A .

Detailed ways

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to better understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but only to illustrate the essence of the technical solutions of the present invention.

FIG. 1 is a schematic perspective view of the three-dimensional structure of the underactuated prosthetic hand based on the continuum transmission mechanism of the present invention. It should be noted that the structure of the prosthetic hand shown in FIG. 1 is only for describing the structure and working principle of the present invention, and should not be construed as limiting the present invention. In addition, it should be pointed out that although it is not shown in FIG. 1 , the prosthetic hand of the present invention also includes a shell similar in shape to a human hand. As shown in Figure 1, the underactuated prosthetic hand based on the continuum transmission mechanism of the present invention includes a motor drive unit 100, a continuum transmission mechanism 200, a manipulator 300 and a base 400, wherein the motor drive unit 100, the continuum transmission mechanism 200 and the manipulator 300 are fixed on the base 400, and the motor drive unit 100 drives the deformation of the continuum transmission mechanism 200, so that the continuum transmission mechanism 200 transmits output to the manipulator 300 to control the manipulator to complete different actions.

FIG. 2 shows a schematic perspective view of the motor drive unit 100 of the prosthetic hand. As shown in FIG. 2 , the motor drive unit 100 includes two similar parts 101 , 102 fixed on the same substrate 1 , wherein the first motor drive part 101 includes a motor 2 , an output gear 3 and two racks 4 , 5 . The motor 2 is fixed on the base plate 1, the output gear 3 is fixedly connected to the output shaft of the motor 2, and the two racks 4 and 5 are meshed on both sides of the output gear 3 in parallel, and each rack such as the rack 4 is connected The plate 6 is fixed on the guide rail 7, or the rack can also be integrally formed with the guide rail. The size of the guide rail 7 matches the size of the chute 8 fixed on the base plate 1 and can slide along the chute 8, so that the rotation of the output gear 3 can drive the two racks to move in different directions, but the movement distance is the same. Drive wires 9 and 10 are respectively fixed on the racks 4 and 5, and are compressed by fixed pressing blocks 11 and 12. When the motor 2 rotates, the driving wires 9 and 10 will make linear push-pull motions.

The second motor driving part 102 has a structure similar to that of the first motor driving part 101, which will not be described in detail here. The two racks of the second motor driving part 102 are also fixedly connected with two driving wires 13 , 14 . When the two parallel motors drive the respective output gears to rotate, the two pairs of racks and their respective guide rails slide along a straight line in the chute, thereby driving the corresponding two pairs of driving wires 9, 10, 13, 14 to perform linear push-pull motion. A pair of drive wires driven by the same motor move at the same speed and in opposite directions. The other end of each driving wire is connected to the continuum transmission mechanism 200, so that the push-pull movement of each driving wire can drive the continuum transmission mechanism to bend into different shapes, which will be further described below.

Preferably, the driving wires 9 , 10 , 13 , 14 are made of highly elastic nickel-titanium alloy wires.

FIG. 3A is a schematic diagram of a continuum transmission mechanism 200 of a prosthetic hand. As shown in Figure 3A, the continuum transmission mechanism 200 includes a fixed plate 36, fixed tubes 15, 16, 17, 18, guide tube 23, base 19, driven wires 24, 25, 26, 27, 28, 29, spacers Disc 20 and locking disc 22. Wherein, one end of the driven wire is fixed on the locking disk 22 , and the other end passes through the spacer disk 20 , the base 19 , the guide tube 23 and the fixing plate 36 sequentially and is finally connected to the manipulator 300 .

Specifically, in the continuum transmission mechanism 200, the base 19 and the fixed plate 36 are fixed on the base 400, and the base 19, the fixed plate 36, the spacer disc 20 and the locking disc 22 all have holes for the driving wire and the driven wire to pass through. The distribution of the small holes is set according to the action of the manipulator to be realized. There are two spacer discs 20 shown in the figure, but it should be understood that the number of spacer discs can also be changed according to actual needs. The fixed tube is arranged between the corresponding apertures on the fixed plate and the base for the drive wire to pass through, and two pairs of drive wires 9, 10, 13, 14 from the motor drive unit pass through the fixed plate 36 and are respectively driven by the fixed tube. 15 , 16 , 17 , 18 are guided to the base 19 , then pass through the base 19 , the spacer disc 20 in turn, and are finally fixed on the locking disc 22 .

A spring 21 is sleeved on the driving wire between adjacent bases 19, spacer discs 20 and locking discs 22, so that each disc can be kept at a certain distance. One end of the guide tube is fixed on the small hole of the base, the other end passes through the fixed plate and extends to the manipulator, and one end of the six driven wires 24, 25, 26, 27, 28, 29 is fastened on the locking disc 22, and the other end It passes through the spacer plate 20 and the base 19 in turn and is guided to the fixed plate 36 by six guide tubes 23 , and is connected with the manipulator after passing through the fixed plate 36 .

Preferably, the driven wires 24, 25, 26, 27, 28, 29 are made of high elastic nickel-titanium alloy wires, the fixing tube is made of metal material, and the guide tube is made of polytetrafluoroethylene material. In the following, for the convenience of description, the structure formed by the part of the driving wire and the driven wire at the rear side of the base 19 as well as the spacer, the spring and the locking disc is called a continuum 38 .

The continuum 38 initially assumes a straight posture. When the motor drives two pairs of drive wires to do push-pull motions, each drive wire is located in a different position in the continuum 38, and the movement of the drive wires drives the continuum 38 to perform a bending motion, thereby resulting in a slave with one end fastened on the locking disc. The moving wire makes a corresponding stretching motion. Figure 3B shows a schematic diagram of the continuum 38 bending downwards to form an arc. The six driven wires are respectively fixed at different positions on the locking disk, and the stretching movement of different driven wires along with the bending movement of the continuum is also Each finger is different, so the six driven wires extending to the manipulator can drive each finger to make a different movement. By changing the rotation direction or speed of the motor, different driving wire outputs can be obtained, thereby obtaining different continuum bending motions, and controlling the manipulator to assume different postures through the driven wire.

FIG. 4A shows a schematic diagram of a manipulator 300 . As shown in Figure 4, the manipulator 300 has a shape and joint structure similar to that of a human hand. The manipulator 300 includes a palm 30, a thumb 31, an index finger 32, a middle finger 33, a ring finger 34 and a little finger 35. Each finger has a plurality of knuckles adjacent to each other. The two knuckles can rotate mutually, the root of the finger is fixed at the proper position of the palm, and the driven wires 24, 25, 26, 27, 28, 29 whose ends are fixed on the locking disc 22 of the continuum transmission mechanism pass through The guide tube 23 enters the palm and is connected to each finger, which will be described in detail below.

Figure 4B shows the structure of the thumb and its connection with the palm; Figure 4C shows the structure of the separated index finger. As shown in Figure 4B, the thumb includes a fingertip 41, a second knuckle 42, a third knuckle 43, a fourth knuckle 44 and a fixed base 45, the fixed base 45 is fixed on the palm by a screw 46, the fourth knuckle Between the knuckles and the fixed base, between the third knuckles and the fourth knuckles, between the second knuckles and the third knuckles, and between the fingertips and the second knuckles are connected by rotating pins and thus have a rotatable joints. The thumb is controlled by two driven wires 24, 25, wherein the driven wire 24 is fixed on the fingertip 41 of the thumb and passes through the second phalanx 42, the third phalanx 43 and the fourth phalanx 44 of the thumb While extending to the outside, the push-pull driven wire 24 realizes the bending or extension of the thumb 31; The wire 25 can realize the abduction or adduction of the thumb 31 .

The index finger 32 , middle finger 33 , ring finger 34 and little finger 35 have different lengths, but have similar structures and are respectively driven by elastic alloy wires 26 , 27 , 28 , and 29 . Taking the index finger as an example, as shown in Figure 4C, the index finger 32 includes a fingertip 47, a second knuckle 48, a third knuckle 49, and a base for the index finger 50, wherein the base for the index finger 50 is fixed on the palm by a screw 46, and the third knuckle is fixed on the palm of the hand by a screw 46. Between the phalanx and the base of the index finger, between the second phalanx and the third phalanx, and between the fingertip and the second phalanx are all connected by rotating pins and thus have rotatable joints. Index finger is controlled by driven wire 26, driven wire 26 is fixed on index finger fingertip 47 and extends to the outside through second knuckle 48, third knuckle 49 and index finger base 50 of index finger, pushing and pulling driven wire 26 can realize Flexion or extension of index finger 32 .

Since the driven wires 24, 26, 27, 28, 29 respectively control the three joints of the thumb, index finger, middle finger, ring finger and little finger, the fingers can adapt to the shape of the contacted object under the action of external force. In addition, torsion springs 37 are installed at each joint, which can keep the fingers extended and stretched when the driven wire is not pushed or pulled.

The underactuated prosthetic hand based on the continuum transmission mechanism of the present invention, when the program controls the motor to rotate at different angles, through the rack and pinion transmission, a pair of driving wires driven by the same motor can push and pull back and forth in opposite directions and at equal distances. Two pairs of drive wires extend to the continuum transmission mechanism as drive inputs for the continuum transmission mechanism. The push-pull movement of the two pairs of driving wires makes the continuum bend in a certain direction into an arc shape, and the driven wire fixed on the locking disc bends accordingly, so that the driven wire also produces a push-pull motion. Six slave wires extend to the continuous body to drive the five fingers of the humanoid prosthetic hand, so that each finger of the prosthetic hand can be bent or unfolded, so as to realize the function of grasping or manipulating objects.

The preferred embodiments of the present invention have been described in detail above, but it should be understood that those skilled in the art can make various changes or modifications to the present invention after reading the above teaching content of the present invention. These equivalent forms also fall within the scope defined by the appended claims of this application.

Claims (10)

1. A kind of underactuated prosthetic hand based on continuum transmission mechanism, it is characterized in that, described prosthesis hand comprises motor drive unit, continuum transmission mechanism and manipulator, wherein, The continuum transmission mechanism includes a fixed plate, a plurality of fixed tubes, a plurality of guide tubes, a base, a plurality of driven wires, a spacer disc and a locking disc, and one end of the fixed tube and the guide tube is connected to the base, the other end of the fixed tube is connected to the fixed plate, one end of the driven wire is fixed on the locking disc, and the other end passes through the spacer disc, the base, the The guide tube and the fixed plate are finally connected to the fingers of the manipulator; The motor drive unit includes a motor, an output mechanism and a plurality of driving wires, one end of the driving wire is fixed on the output mechanism, and the other end passes through the fixing plate, the fixing tube, the base and the the spacer disc, fastened to the shrink disc; and The manipulator includes a palm and five fingers, each finger has a plurality of knuckles, and two adjacent knuckles are rotatably connected; wherein, The rotation of the motor of the motor drive unit can be converted into the linear motion of the driving wire through the output mechanism, and the linear motion of the driving wire can drive the deformation of the continuum transmission mechanism, so that one end is connected to the continuum The driven wire fixed by the locking disk of the transmission mechanism moves, thereby driving each finger of the manipulator to complete corresponding actions. 2. The underactuated prosthetic hand as claimed in claim 1, wherein the output mechanism comprises a base plate, an output gear, a rack, a guide rail and a chute, and the output gear is fixedly connected to the output shaft of the motor, and the two The root racks are meshed on both sides of each output gear in parallel, each rack is fixed on the guide rail, the size of the guide rail matches the size of the chute fixed on the base plate and can slide along the chute, the drive wire and The rack is fixedly connected. 3. The underactuated prosthetic hand of claim 2, wherein the motor drive unit comprises two motors and two output gears, the two motors are connected via the two output gears and the rack A total of four driving wires are driven. 4. The underactuated prosthetic hand of claim 1, wherein the base, the fixed plate, the spacer disc and the locking disc all have apertures for the drive wire and the driven wire to pass through , the distribution of the small holes is set according to the action of the manipulator to be realized. 5. The under-actuated prosthetic hand according to claim 4, wherein the fixing tube is arranged between the fixing plate and the corresponding small hole for the driving wire to pass through on the base, the One end of the guide pipe is fixed on the small hole of the base, and the other end passes through the fixing plate and extends to the manipulator. 6. The under-actuated prosthetic hand as claimed in claim 1, characterized in that, several driving wires and/or driven wires passing between adjacent bases, spacer discs and locking discs are covered with springs , so that a certain distance is maintained between the base, the spacer disc and the locking disc. 7. The underactuated prosthetic hand of claim 1 , wherein the five fingers comprise a thumb comprising a fingertip, a second knuckle, a third knuckle, a fourth knuckle and The fixed base is fixed on the palm of the hand by screws, and a driven wire of the continuum transmission mechanism passes through the fourth knuckle, the third knuckle and the second knuckle of the thumb and is fixed on the The fingertip of the thumb, the push-pull movement of this driven wire can realize the bending or extension of the thumb; the other driven wire of the continuum transmission mechanism passes through the palm and the fixed base and is fixed on The fourth knuckle of the thumb, the push-pull movement of this driven wire can realize the abduction or adduction of the thumb. 8. The underactuated prosthetic hand of claim 1, wherein said five fingers comprise an index finger, middle finger, ring finger, and little finger, said index finger, middle finger, ring finger, and little finger having similar structures, wherein each finger It includes the fingertip, the second knuckle, the third knuckle and the finger base, the finger base is fixed on the palm by screws, and the four driven wires of the continuum transmission mechanism respectively pass through the palm and the corresponding fingers The finger base, the third phalanx, and the second phalanx are fixed on the fingertips of the corresponding fingers, and the push-pull movement of each driven wire can respectively realize the bending or stretching of the index finger, middle finger, ring finger and little finger. 9. The underactuated prosthetic hand as claimed in claim 7 or 8, wherein two adjacent knuckles are connected by a rotating pin to form a rotatable joint, and the joint is provided with a torsion spring, so that the When the above-mentioned driven wire does not pull the finger to move, the finger can keep spreading and straightening. 10. The under-actuated prosthetic hand as claimed in claim 1, wherein the driving wire and the driven wire are made of highly elastic nickel-titanium alloy wire, the fixing tube is made of metal material, and the The guide tube is made of polytetrafluoroethylene material.