CN103690279A - An underactuated prosthetic hand system based on a planetary gear train - Google Patents

Abstract

The invention discloses an under-actuated prosthetic hand system based on planetary gear trains. The under-actuated prosthetic hand system is used for realizing continuous hand motions. The under-actuated prosthetic hand system comprises three parts, namely a driving system, a transmission system and a mechanical hand, wherein the driving system comprises stepping motors and the planetary gear trains, the transmission system comprises transmission mechanisms such as flexible shafts, worm gears and worm rods, the mechanical hand comprises a palm and five fingers, and each finger is provided with multiple rotational joints. The input of two stepping motors can be converted into the rotation of thirteen output flexible shafts by the planetary gear trains in the driving system through a cooperative action mode, thus the motion of each joint on the mechanical hand can be cooperatively controlled, and some grabbing motions in daily life and the motion of rotating a rehabilitation training ball can be realized by the mechanical hand. According to the under-actuated prosthetic hand system disclosed by the invention, complicated grabbing motions are realized just through a two-input mode, the motion of the mechanical hand can be controlled by a disabled person who is in lack of a hand through less but accurate muscle signals, and the under-actuated prosthetic hand system has the advantages that the flexibility is high, and the use is convenient.

Description

An underactuated prosthetic hand system based on a planetary gear train

technical field

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

Background technique

A particularly challenging task when attempting to recreate motor function in a disabled person who has lost a hand is to create a prosthetic hand that has an anthropomorphic form that correctly reproduces the delicate movements of the original. To achieve this goal, the prosthetic hand needs to be able to adapt to a variety of daily movements and can be controlled by the amputee's biosignal interface, such as myoelectric and brain signals. There are many advanced fully-driven anthropomorphic robot hands in the world today, most of which use more inputs to control the various degrees of freedom of the hand, but due to the limited ability to analyze and acquire existing electromyographic signals, many existing bionic The hand is designed using an underactuated approach where the number of driven inputs is less than the number of outputs. Recent advances in neurology have shown that the way the central nervous system controls the hand's muscle coordination is known as a synergistic effect on posture. The synergy of each position corresponds to the flexion/extension drive of the hand muscles. The central nervous system uses the synergistic effect of postures to achieve different hand movements by adjusting the proportion (or coefficient) of each synergy. Among them, the synergistic effect of combining two main positions accounts for about 84% of dozens of grasping poses.

These findings make it possible to efficiently control a robotic hand with fewer inputs, and achieving postural synergy and minimizing the number of input axes through mechanical structures will greatly reduce the cost of prosthetic hands.

Contents of the invention

The purpose of the present invention is to make the prosthetic hand convert two sets of inputs into thirteen sets of synergistic outputs through the planetary gear train in an under-driven manner, so as to drive the manipulator to complete different grasping actions.

In order to achieve the above purpose, the present invention provides a prosthetic hand system based on a planetary gear train, which can realize different motion synthesis of two inputs through different transmission ratios and different input and output modes of multiple sets of planetary gear trains, thereby synergistically Control each group of outputs, and then transmit the effects of these outputs to the manipulator through the transmission system. Since each output corresponds to each joint on the manipulator, the manipulator can complete different grasping actions.

The prosthetic hand system based on the planetary gear train of the present invention consists of three parts: a drive system, a transmission system and a manipulator. The drive system consists of two stepper motors and a gearbox consisting of eight gear trains. The stepping motor is controlled by a relatively simple integrated board and corresponding control program, in which the purpose of precise control can be achieved by modifying its rotation direction, angle and speed. The gearbox is the most critical part of this invention. It includes two input shafts and thirteen output shafts. The two input shafts are controlled by two stepping motors respectively, and the thirteen output shafts are controlled by seven sets of planetary gear trains. and a common set of gear train controls. The seven sets of planetary gear train combine the two inputs through different gear reduction ratios and different input and output modes of the sun gear, planetary gear and peripheral gear (that is, two of the three gears are used as input, and the remaining one is used as output). And converted into corresponding eleven outputs, that is, a set of planetary gear trains can correspond to multiple outputs. The role of the remaining set of ordinary gear trains is to convert the separate input into two sets of separate outputs through the gear reduction ratio.

The transmission system includes a flexible shaft and the output shaft of the worm gear corresponding to the flexible shaft is connected to the corresponding flexible shaft through a coupling, and the other end of the flexible shaft is also fixed with a coupling to fix the flexible shaft and the worm, and then the worm drives the turbine. , to drive the motion of the corresponding joints in the finger-level palm. Therefore, the transmission system converts the rotation of the output shaft into the rotation of the turbine through the reduction ratio of the worm gear. Because the flexible shaft has a good torque, coupled with the 1:20 reduction ratio of the worm gear, the transmission error on the flexible shaft is reflected. There is only one-twentieth of the original after the turbine, so there is a negligible transmission error in this transmission chain. The transmission system also includes transmission mechanisms such as sliders and connecting rods.

The manipulator includes the palm and five fingers. The thirteen output shafts of the drive system correspond to the thirteen joints of the five fingers, including the metacarpophalangeal joints and proximal interphalangeal joints of the index finger, middle finger, ring finger and little finger, and a common Abduction joints, and interphalangeal joints of the thumb, metacarpophalangeal joints, terminal rotator joints and abduction joints, index, middle, ring, and little fingers also include distal interphalangeal joints, a set of distal interphalangeal joints and proximal phalangeal joints The inter-joint is controlled by an output shaft. The palm part includes the upper and lower cover plates and the shaft holes and screw holes required to fix the five fingers. Inside the palm, there is a drive mechanism for the abduction of four fingers driven by a slide bar, and this group of mechanisms is also controlled by a flexible shaft. For the five fingers, the configuration of the index finger, middle finger, ring finger and little finger is similar, and the difference is only reflected in the length of each knuckle. The transmission chain of these four fingers is based on the link mechanism, and the turbine installed at the metacarpophalangeal joint drives the movement of the link, thereby controlling the rotation of the interphalangeal joint and the proximal interphalangeal joint. For the thumb, considering the relative complexity of its structure, a gear chain is used as the transmission mode, and considering the rotation angle of the flexible shaft, a set of smaller planetary gear reducers are used at the thumb end rotary joint to achieve a suitable reduction ratio.

An underactuated prosthetic hand system based on a planetary gear train. The prosthetic hand system includes a drive system, a transmission system and a manipulator. The drive system includes a stepper motor and a planetary gearbox. The planetary gearbox includes an input shaft and an output shaft. The motor is connected with the input shaft of the planetary gearbox; the manipulator includes the palm and five fingers, and there are movable joints on the fingers; and the transmission system includes a flexible shaft and a transmission mechanism, one end of the flexible shaft is connected with the output shaft, and the other end of the flexible shaft It is connected to each joint of the manipulator through a transmission mechanism; among them, the planetary gearbox can convert the input of the stepper motor into the rotation of the output shaft through a synergistic effect and transmit it to the manipulator through the transmission system to cooperatively control the movement of each joint on the manipulator.

Preferably, the planetary gearbox also includes a planetary gear train, a common gear train, an idler shaft and a separator, each set of gear trains includes an input gear and an output gear, and some gear trains also include an idler gear, and each set of gear trains is located in an adjacent Between the two partitions, the input shaft, output shaft and idler shaft all pass through the partition and are respectively fixedly connected with the input gear, output gear and idler gear of each group of gear trains through a tightening device.

Preferably, the planetary gear train includes a sun gear, a peripheral gear, a planetary gear, an idler gear and a driving gear, and the rotation of the two gears in the sun gear, the peripheral gear and the planetary gear is controlled by two input shafts, and the other gear is connected to the The rotation generated by the cooperation of the two gears is transmitted to the output shaft; the ordinary gear train converts the independent rotational input of each input shaft into an independent rotational output.

Preferably, the planetary gearbox includes seven sets of planetary gear trains, one set of common gear trains, two input shafts, thirteen output shafts, six idler shafts and nine spacers, and the seven sets of planetary gear trains combine the two input shafts The rotation input is synthesized and converted into eleven kinds of rotation outputs. A set of ordinary gear trains converts the independent rotation inputs of two input shafts into two independent rotation outputs, so that the drive system has a total of thirteen kinds of outputs; the transmission system includes ten Three flexible shafts, one end of each flexible shaft is fixedly connected with an output shaft of the drive system through a coupling.

Preferably, the transmission mechanism includes a worm gear and a connecting rod. The five fingers of the manipulator include a thumb, and the thumb includes a first knuckle, a second knuckle and a third knuckle, and adjacent knuckles can rotate mutually to have Interphalangeal joints and metacarpophalangeal joints, the root of the thumb also has a terminal rotation joint and abduction joint, wherein the terminal rotation joint is connected with a flexible shaft; the abduction joint is connected with a worm gear, and the worm gear matched with the worm gear is passed through the coupling The organ is connected with a flexible shaft; the metacarpophalangeal joint is connected with a flexible shaft through a worm gear; and the interphalangeal joint is connected with a flexible shaft through a connecting rod and a worm gear.

Preferably, a small reduction gear is connected to the rotary joint at the end of the thumb, and the small reduction gear is fixedly connected to a flexible shaft through a coupling.

Preferably, the metacarpophalangeal joints are further provided with a set of several intermeshing gears engaged with corresponding worm gears, one of which is fixedly connected to the second knuckle of the thumb, and the worm gear is rotatably connected to the third knuckle of the thumb, The corresponding worm meshes with the worm gear and is fixedly connected with a flexible shaft through a coupling; one end of the connecting rod is fixedly connected with the first knuckle of the thumb, and several mutual knuckles are rotatably connected on the third knuckle of the thumb. Meshing gears and worm gears, one of the gears is fixedly connected with the second knuckle of the thumb and the other end of the connecting rod, the worm meshed with the worm gear is fixedly connected with another flexible shaft through a coupling, and the connecting rod directly controls the interphalangeal joints rotation.

Preferably, the transmission mechanism includes a worm gear and a connecting rod. The four fingers of the manipulator except the thumb include the index finger, middle finger, ring finger and little finger. These four fingers have similar dimensions and are all connected to the palm through the finger base. Each finger includes the first knuckle, the second knuckle, the third knuckle, the proximal interphalangeal joint, the distal interphalangeal joint and the metacarpophalangeal joint. Adjacent knuckles can rotate with each other. The third knuckle is rotatably connected to the finger base, one of the worm gears is fixedly connected to the third knuckle, and the worm meshed with the worm gear is fixedly connected to a flexible shaft through a coupling; the other worm gear is fixedly connected to the finger base. Rotationally connected, the two ends of the first connecting rod are respectively rotatably connected with the worm wheel and the second knuckle, and the two ends of the second connecting rod are respectively rotatably connected with the second knuckle and the first knuckle of the index finger. The worm meshed with the worm gear is fixedly connected with another flexible shaft through a shaft coupling.

Preferably, the transmission mechanism also includes a slide bar, the slide bar is provided with a groove, and the four fingers of the manipulator except the thumb also have a common abduction joint, and the abduction joint has a pushing element and three abduction elements, which push The elements can slide along the grooves in the slide bar, and the pushing element is provided with three chute slots, one end of the three outreaching elements can slide in the corresponding chute on the pushing element respectively, and the other end of the three outreaching elements is connected with the four fingers. The finger bases of the three fingers are fixedly connected and have their own rotating shafts fixed on the palm. The sliding rod is connected with a flexible shaft through a coupling. The rotation of the flexible shaft can drive the sliding rod to rotate, thereby driving the front and rear of the pushing element In translation, one end of the abduction element slides in the chute and the other end rotates around its respective rotation axis, thereby driving the finger bases of the three fingers to rotate correspondingly to realize the abduction movement of the four fingers.

Preferably, the planetary gearbox has two or three input shafts.

The underactuated prosthetic hand system based on the planetary gear train of the present invention realizes the synergistic effect of different joints of each finger of the manipulator through the mechanical structure of the planetary gear train, reduces the number of input shafts to two, and reduces the cost of the prosthetic hand. At the same time, the prosthetic hand can simulate the grasping action of the human hand very well.

Description of drawings

Fig. 1 is the overall assembly diagram of the underactuated prosthetic hand system based on the planetary gear train of the present invention;

FIG. 2A is a three-dimensional schematic diagram of a planetary gearbox of the drive system in FIG. 1;

Fig. 2B is an exploded view of a group of planetary gear trains in Fig. 2A;

FIG. 2C is a schematic perspective view of the planetary gear train in FIG. 2B;

Figure 2D is a side view of the planetary gearbox of the drive system in Figure 2A;

Figure 2E is a front view of the planetary gearbox of the drive system in Figure 2A;

Fig. 3 is a schematic diagram of a group of transmission systems based on flexible shafts and worm gears in Fig. 1;

Fig. 4 is the three-dimensional schematic view of the manipulator in Fig. 1 after removing the upper cover;

Fig. 5A is a transmission schematic diagram of the thumb of the manipulator in Fig. 1;

Fig. 5B is a transmission principle diagram of the metacarpophalangeal joint of the thumb in Fig. 5A;

Fig. 6A is a transmission principle diagram of the index finger of the manipulator in Fig. 1;

Fig. 6B is a schematic diagram of the transmission principle of the interphalangeal joint of the index finger in Fig. 6A; and

Fig. 7 is a transmission principle diagram of the abduction mechanism of the manipulator in Fig. 1 .

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 shows a perspective schematic view of the overall assembled underactuated prosthetic hand system based on the planetary gear train of the present invention. As shown in Fig. 1, the underactuated prosthetic hand system based on the planetary gear train of the present invention includes a manipulator 100, a transmission system 200 and a drive system 300, wherein the two ends of the transmission system 200 are respectively connected with the manipulator 100 and the drive system 300, and the transmission system 200 transmits the output of the driving end 300 to the manipulator 100 so that the manipulator 100 completes different actions.

The drive system 300 includes two stepper motors and a planetary gearbox. In the embodiment shown in the figure, the planetary gearbox includes multiple sets of planetary gear trains and common gear trains. The two stepper motors are controlled by the integrated board and the corresponding control program, and are connected to the two input shafts of the gear train. The rotation direction, speed and angle of the stepper motor are set through the control program to precisely control the stepper motor to control Input and output of planetary gearbox.

FIG. 2A is a schematic perspective view of the planetary gearbox 301 of the driving system 300 in FIG. 1 . As shown in Figure 2A, the planetary gearbox includes seven sets of planetary gear trains 10, a set of common gear trains 20, two input shafts 30, thirteen output shafts 40, six idler shafts 50 and nine stainless steel plates 60, ten Three output shafts 40 expose the longer length of the stainless steel plate than the six idler shafts. It should be pointed out that, as required, the number of input shafts 30 may also be three or the like. The stainless steel plate 60 can also be a separator made of other materials, and its number is determined according to the number of gear trains contained in the planetary gearbox.

The two input shafts 30 of the planetary gearbox 301 are respectively controlled by two stepper motors (not shown) of the drive system 300; the thirteen output shafts 40 are controlled by seven sets of planetary gear trains 10 and one set of ordinary gear trains 20 The idler gears installed on the six idler shafts 50 are used to change the direction of rotation of the output shafts in several groups of gear trains; all input shafts 30, output shafts 40 and idler shafts 50 are respectively run through nine stainless steel plates 60, nine stainless steel plates Plate 60 functions to separate the eight sets of gear trains and enhance system stability. Here, the stainless steel plate 60 may also be a plate-like piece made of a suitable material, such as plastic.

Fig. 2B is an exploded view of a set of planetary gear trains in Fig. 2A. As shown in FIG. 2B , the set of planetary gear trains includes a sun gear 5 , a peripheral gear 4 , planetary gears 7 and other auxiliary gears. The first input gear 1 is fixedly connected to the first input shaft through the tightening device 2. The first input gear 1 and the tightening device 2 are provided with matching pin holes and fixed by two pins. There are two fastening screw holes, and the fastening device 2 together with the first input gear 1 is fixed on the first input shaft by screws. The driving gear 3 meshes with the first input gear 1 and the driving gear 3 is fixed to the peripheral wheel 4 through four pins, so that the first input shaft controls the rotation of the peripheral wheel. Similarly, the sun gear (that is, the second input gear) 5 is fixedly connected to the second input shaft through the tightening device 6; the planetary gear 7 is engaged between the peripheral gear 4 and the sun gear 5 and is connected to the The driving gear 9 is fixed; the output gear 11 is fixedly connected to the output shaft through the tightening device 12; the idler gear 89 is engaged between the driving gear 9 and the output gear 11 so that the output gear 11 rotates in the opposite direction to the driving gear 9.

FIG. 2C is a schematic perspective view of the planetary gear train in FIG. 2B . As shown in FIG. 2C , after the installation is completed, the axes of the driving gear 3 , the peripheral wheel 4 , the sun gear 5 and the driving gear 9 are all the same as the axes of the second input shaft. The rotation of the first input gear 1 and the sun gear (that is, the second input gear) 5 fixedly connected to the first input shaft and the second input shaft respectively are transmitted to the output gear 11 fixedly connected to the output shaft through the combination of gear trains .

FIG. 2D is a side view of the planetary gearbox of the drive system in FIG. 2A; each of the seven sets of planetary gear trains 10 includes sun gears, planetary gears, peripheral gears and other auxiliary gears. In each set of planetary gear trains, two gears in the sun gear, planetary gear and peripheral gear are used as input, and the other gear is used as output. For example, in the planetary gear train shown in Figure 2B, the peripheral gear and sun gear are used as input , the planetary gear as the output. A set of planetary gear trains can have multiple output gears connected to the output shaft by adding auxiliary gears. Different gear coordination can result in different gear reduction ratios and different gear rotation directions, thereby achieving different outputs. In the present invention, seven sets of planetary gear trains 10 synthesize and convert the rotational inputs of the two input shafts into eleven rotational outputs, and a set of ordinary gear trains convert the individual rotational inputs of the two input shafts into two through the gear reduction ratio. Separate rotation output, so that the drive system has a total of thirteen outputs.

It should be pointed out that the planetary gearbox can include three or more input shafts, each input shaft is controlled by a stepper motor, and the rotation input of each set of gear trains can come from any two or two of the above-mentioned input shafts as required. above.

Figure 2E is a front view of the planetary gear train, from which the cross-sections of each input shaft, output shaft and idler shaft can be seen. Thirteen kinds of outputs of the thirteen output shafts of the drive system 300 are respectively used to control corresponding joints on the manipulator 100 . Specifically, as shown in Figure 2E, and referring to Figure 4, the output shaft 41 corresponds to the thumb end rotary joint 61; the output shaft 42 corresponds to the thumb metacarpophalangeal joint 62; the output shaft 43 corresponds to the thumb interphalangeal joint 63; the output shaft 44 The output shaft 45 corresponds to the metacarpophalangeal joint 65 of the index finger; the output shaft 46 corresponds to the metacarpophalangeal joint 66 of the middle finger; the output shaft 47 corresponds to the metacarpophalangeal joint 67 of the ring finger; the output shaft 48 corresponds to the metacarpophalangeal joint 68 of the little finger; 49 corresponds to the proximal interphalangeal joint 69A of the index finger and the distal interphalangeal joint 69B of the index finger; the output shaft 410 corresponds to the proximal interphalangeal joint 610A of the middle finger and the distal interphalangeal joint 610B of the middle finger; the output shaft 411 corresponds to the proximal interphalangeal joint 611A of the ring finger and The distal interphalangeal joint 611B of the ring finger; the output shaft 412 corresponds to the proximal interphalangeal joint 612A of the little finger and the distal interphalangeal joint 612B of the little finger; the output shaft 413 corresponds to the abduction joints 613 of the index finger, middle finger, ring finger and little finger. See below for a detailed description of the manipulator.

The transmission system 200 includes thirteen flexible shafts and a transmission mechanism, such as a worm gear, a sliding rod and a connecting rod. Fig. 3 is a schematic diagram of a group of transmission systems based on flexible shafts and worm gears in Fig. 1 . As shown in FIG. 3 , the output shaft 40 is fixedly connected to one end of the corresponding flexible shaft 13 through the coupling 14 , and the other end of the flexible shaft 13 is fixedly connected to the worm 17 through the coupling 15 , and the worm 17 is meshed with the worm wheel 16 . When the drive system controls the rotation of the output shaft 40, the worm 17 also rotates accordingly, and the worm wheel 16 matched with the worm 17 rotates, and the movement of the worm wheel 16 drives the movement of the corresponding components in the manipulator 100 to drive the movement of the corresponding joints in the manipulator. The diameter of the output shaft 40 is, for example, 2 millimeters, and the diameter of the flexible shaft 13 is, for example, 3.2 millimeters. Correspondingly, the inner diameter of one end of the shaft coupling 14 is 2 millimeters and the inner diameter of the other end is 3.2 millimeters. It is 3.2 mm and the inner diameter of the other end is equal to the diameter of the end of the worm.

It can be seen from this that the transmission system 200 converts the rotation of the output shaft into the rotation of the turbine through the reduction ratio of the worm gear, and the flexible shaft is made of a material that can transmit torque well so that the rotation of the output shaft can be effectively transmitted. And the reduction ratio of the worm gear is 1:20, the transmission error reflected on the turbine is only one-twentieth of the transmission error of the flexible shaft, so the transmission error of the transmission chain can be ignored.

The manipulator includes a palm, five fingers, and a linkage-based kinematic transmission chain. In order to see the internal mechanism of the manipulator more clearly, FIG. 4 shows a schematic perspective view of the manipulator after removing the upper cover. As shown in Figure 4, the manipulator 100 includes a palm, a thumb 18, four fingers 19 with similar structures, and an outstretching mechanism 52 for the four fingers 19, wherein the palm includes upper and lower cover plates and shaft holes and screw holes required for fixing five fingers , the four fingers 19 include the index finger, middle finger, ring finger and little finger, and the abduction mechanism 52 is located inside the palm.

As mentioned above, the thirteen kinds of outputs of the drive system 300 are respectively used to control the corresponding joints on the manipulator 100: the thumb 18 has an interphalangeal joint 63, a metacarpophalangeal joint 62, an end rotation joint 61 and an abduction joint 64; Any one finger in 19, such as the index finger, has a distal interphalangeal joint 69B, a proximal interphalangeal joint 69A, and a metacarpophalangeal joint 65; the four fingers 19 also have a common abduction joint 613.

FIG. 5A is a transmission schematic diagram of the thumb 18 of the manipulator in FIG. 1 , in order to see its internal structure clearly, some components are deleted in the figure. One end of the flexible shaft (not shown) connected to the output shaft 41 is connected to the coupling 21 at the base of the thumb in the figure, and a small planetary gear reducer 22 is used to achieve a suitable reduction ratio to control the rotation of the thumb end rotary joint 61 Rotation; one end of the flexible shaft (not shown) connected to the output shaft 44 is connected to the coupling 23 near the thumb abduction joint and the rotation of the thumb abduction joint 64 is controlled through the cooperation of the worm 24 and the worm wheel 25; One end of the flexible shaft (not shown) connected to the output shaft 43 is connected to the coupling 26 and through the transmission chain of the worm 27, the worm wheel 28, the gear 29, the gear 33 and the connecting rod 34 to control the interphalangeal joint 63 of the thumb Purpose, wherein the gear 33 is rotatably connected to the second knuckle 78 of the thumb, and the two ends of the connecting rod 34 are fixedly connected to the gear 33 and the first knuckle 84 of the thumb respectively.

The related structures controlling the metacarpophalangeal joint of the thumb cannot be seen in FIG. 5A , so the transmission principle of the metacarpophalangeal joint of the thumb is shown separately in FIG. 5B . As shown in Figure 5B, a flexible shaft (not shown) connected to the output shaft 42 at one end is connected to the coupling 71 and transmits the motion to the gear 74 through the worm 75, the worm wheel 72, the gear 86, and the gear 73, wherein the worm wheel 72 and The gear 73 is rotatably connected to the third knuckle 85 of the thumb, the gear 86 is fixedly connected to the worm gear 72, and the gear 74 is fixedly connected to the second knuckle 78 of the thumb, so that the rotation of the gear 74 completes the rotation of the metacarpophalangeal joint of the thumb. turn.

FIG. 6A is a schematic diagram of the transmission principle of the index finger of the manipulator in FIG. 1 . As shown in Figure 6A, the shaft coupling 35 is connected to the output shaft that controls the proximal interphalangeal joint 69A of the index finger and the distal interphalangeal joint 69B of the index finger, and the flexible shaft that one end is connected to the output shaft 45 that controls the metacarpophalangeal joint of the index finger is connected to the coupling. Shaft device 76, the output of output shaft 45 is delivered to worm screw 77 by flexible shaft, and the worm wheel 79 that cooperates with worm screw 77 is fixedly connected with the third knuckle 83 of index finger, and the rotation of worm wheel 79 has promptly finished the rotation of index finger metacarpophalangeal joint.

In order to clearly see the transmission principle of the proximal interphalangeal joint 69A of the index finger and the distal interphalangeal joint 69B of the index finger, some components are removed in FIG. 6B . As shown in Figure 6B, the worm wheel 37 is rotatably connected to the third knuckle 83 of the index finger, the two ends of the connecting rod 38 are fixedly connected to the worm wheel 37 and the second knuckle 82 of the index finger respectively, and the two ends of the connecting rod 39 are respectively connected to the second knuckle 82 of the index finger. The second phalanx 82 is fixedly connected with the first phalanx 81 . One end of the flexible shaft connected to the output shaft 49 (not shown in the figure) is connected to the coupling 35, the output of the output shaft 49 is transmitted to the worm 36 through the flexible shaft, and through the transmission chain composed of the worm wheel 37, the connecting rod 38 and the connecting rod 39 To control the rotation of the index finger proximal interphalangeal joint 69A and the index finger distal interphalangeal joint 69B.

The remaining three fingers, namely the middle finger, ring finger and little finger, have a transmission principle similar to that of the index finger.

Fig. 7 shows the transmission schematic diagram of the abduction mechanism of the manipulator. The output shaft 413 is connected with the coupling 51 in the abduction joint 613 through a flexible shaft, the rotation of the output shaft 413 can drive the slide bar 55 to rotate, and the pushing element 56 cooperating with the slide bar 55 produces a translational movement with the rotation of the slide bar 55 , the pushing element 56 is provided with three inclined slots 57 , with the translational movement of the pushing element 56 , the three outreaching elements 53 can slide in the corresponding inclined slots 57 and rotate around the respective fixed rotating shafts 54 . As can be seen from Fig. 4, the three abduction elements 53 are respectively fixedly connected with the finger bases 78 of the corresponding index finger, ring finger, and little finger, and each finger base 78 rotates with the rotation of the abduction elements 53, thereby driving the index finger, ring finger, and little finger. Abduction of the ring finger and little finger.

The underactuated prosthetic hand system based on the planetary gear train of the present invention realizes the synergistic effect of different joints of each finger of the manipulator through the mechanical structure of the planetary gear train, reduces the number of input shafts to two, and reduces the cost of the prosthetic hand. At the same time, the prosthetic hand can simulate the grasping action of the human hand very well.

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. An under-actuated prosthetic hand system based on a planetary gear train is characterized by comprising a driving system, a transmission system and a mechanical hand, wherein the driving system, the transmission system and the mechanical hand are arranged in a combined mode

The driving system comprises a stepping motor and a planetary gear box, the planetary gear box comprises an input shaft and an output shaft, and the stepping motor is connected with the input shaft of the planetary gear box;

the manipulator comprises a palm and five fingers, and movable joints are arranged on the fingers; and

the transmission system comprises a flexible shaft and a transmission mechanism, one end of the flexible shaft is connected with the output shaft, and the other end of the flexible shaft is connected with each joint of the manipulator through the transmission mechanism; wherein,

the planetary gear box can convert the input of the stepping motor into the rotation of the output shaft in a cooperative action mode and transmit the rotation to the mechanical arm through the transmission system so as to cooperatively control the motion of each joint on the mechanical arm.

2. A prosthetic hand system according to claim 1, wherein the planetary gearbox further comprises planetary gear trains, a common gear train, idler shafts and spacers, each train comprising an input gear and an output gear, some of the gear trains further comprising an idler, each train being located between two adjacent spacers, the input shaft, the output shaft and the idler shaft each extending through a spacer and being fixedly connected to the input gear, the output gear and the idler of each train by tightening means.

3. A prosthetic hand system according to claim 2, wherein the epicyclic gear train comprises a sun gear, a peripheral gear, planet gears, an idler gear and a drive gear, the rotation of two of the sun gear, the peripheral gear and the planet gears being controlled by two input shafts, the rotation of the other gear in cooperation with the two gears being transmitted to the output shaft; the common gear train converts the independent rotational input of each input shaft into an independent rotational output.

4. A prosthetic hand system according to claim 3, wherein the planetary gear box comprises seven sets of planetary gears which combine and convert the rotational inputs of the two input shafts into eleven rotational outputs, a set of common gear trains which convert the independent rotational inputs of the two input shafts into two independent rotational outputs, such that the drive system has thirteen outputs, a set of common gear trains, thirteen output shafts, six idler shafts and nine bulkheads; the transmission system comprises thirteen flexible shafts, and one end of each flexible shaft is fixedly connected with one output shaft of the driving system through a coupler.

5. The prosthetic hand system of claim 4, wherein the transmission comprises a worm gear and a connecting rod, wherein the five fingers of the manipulator comprise a thumb comprising a first knuckle, a second knuckle and a third knuckle, wherein adjacent knuckles are rotatable with respect to each other to define an interphalangeal joint and a metacarpophalangeal joint, and wherein the base of the thumb further defines a distal revolute joint and a abduction joint, wherein,

the tail end rotary joint is connected with a flexible shaft;

a worm wheel is connected to the abduction joint, and a worm matched with the worm wheel is connected with a flexible shaft through a coupler;

the metacarpophalangeal joint is connected with a flexible shaft through a worm gear and a worm; and

the interphalangeal joint is connected with a flexible shaft through a connecting rod and a worm gear.

6. The prosthetic hand system of claim 5, wherein a small reduction gear is connected to a distal rotary joint of the thumb and fixedly connected to a flexible shaft by a coupling.

7. A prosthetic hand system as claimed in claim 5, wherein a plurality of intermeshing gears are provided at the metacarpophalangeal joints in mesh with respective worm gears, one of which is fixedly connected to the second knuckle of the thumb, the worm gear being rotatably connected to the third knuckle of the thumb, the respective worm being in mesh with the worm gear and fixedly connected to a flexible shaft by means of a coupling;

one end of the connecting rod is fixedly connected with the first knuckle of the thumb, a plurality of gears and worm gears which are meshed with each other are rotatably connected to the third knuckle of the thumb, one of the gears is fixedly connected with the second knuckle of the thumb and the other end of the connecting rod, the worm meshed with the worm gear is fixedly connected with the other flexible shaft through a coupler, and the connecting rod directly controls the rotation of the interphalangeal joint.

8. The prosthetic hand system of claim 4, wherein the transmission mechanism includes a worm gear and a connecting rod, the four fingers of the manipulator other than the thumb include an index finger, a middle finger, a ring finger and a small finger, the four fingers being of similar size and each being connected to the palm of the hand by a finger base, each finger including a first knuckle, a second knuckle, a third knuckle, and a proximal interphalangeal joint, a distal interphalangeal joint and a metacarpophalangeal joint, adjacent knuckles being mutually rotatable, the third knuckle of each finger being rotatably connected to the finger base, wherein,

a worm wheel is fixedly connected with the third knuckle, and a worm meshed with the worm wheel is fixedly connected with a flexible shaft through a coupling;

the other worm wheel is rotatably connected with the finger base, two ends of the first connecting rod are rotatably connected with the worm wheel and the second knuckle respectively, two ends of the second connecting rod are rotatably connected with the second knuckle of the index finger and the first knuckle respectively, and the worm meshed with the worm wheel is fixedly connected with the other flexible shaft through a coupler.

9. A prosthetic hand system according to claim 8, wherein the transmission mechanism further comprises a sliding bar having a slot, four fingers of the manipulator other than the thumb having a common abduction joint having a pushing element and three abduction elements, the pushing element being slidable along the slot in the sliding bar, the pushing element having three inclined slots, one end of each of the three abduction elements being slidable in a corresponding inclined slot in the pushing element, the other end of each of the three abduction elements being fixed to a finger base of three of the four fingers and having a respective rotary shaft fixed to the palm, the sliding bar being connected to a flexible shaft by a coupling, rotation of the flexible shaft driving the sliding bar to move the pushing element to translate back and forth, rotation of the abduction elements having one end sliding in the inclined slots and the other end rotating about the respective rotary shaft, thereby driving the finger bases of the three fingers to correspondingly rotate and realizing the abduction motion of the four fingers.

10. A prosthetic hand system according to claim 3, wherein the planetary gearbox has two or three input shafts.

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