Thumb carpal joint of bionic hand

Abstract

A thumb carpometacarpal joint of a bionic hand relates to the technical field of bionic hands and comprises a buffer mechanism, the buffer mechanism comprises a buffer pad, the top of the buffer pad is fixedly connected with two piston rods, the tops of the piston rods are fixedly connected with first springs, and the piston rods are slidably connected with a fixing plate; through cooperation of structures such as a buffer pad and a piston rod, the problem that when the device makes contact with an object, large pressure is caused to the contact position of the object and the bionic hand due to large rigidity, and therefore the object is abraded is solved; the force applied by the near-end finger plate to the buffer pad and the surface of an object is buffered through the air pressure in the sealed cabins and the elastic force of the first spring, and meanwhile, air in one sealed cabin extrudes the interior of the air bag through the vent hole, so that the air bag is filled, the thumb shell is fully attached to the object, and the contact area and the flexible area are increased; and the grabbing stability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of bionic hands, in particular to a thumb carpometacarpal joint of a bionic hand. Background Art

[0002] The thumb-carp-metacarpal joint design of the bionic hand is a perfect combination of bionics and mechanical engineering, aiming to provide amputees with flexibility and functionality similar to physiological hand movements. In nature, the human thumb is an important part of the hand function, with unique rotation and palm-opposition capabilities, enabling fine operations such as holding, grasping and sensing. The thumb is the most powerful finger in the human hand. Unlike the other four fingers, the lowest joint of the thumb is not the metacarpophalangeal joint, but the carp-metacarpal joint. The movements of the thumb-carp-metacarpal joint are relatively complex and play a key role in the movements of the thumb. Most of the thumb movements are mainly movements of the carp-metacarpal joint.

[0003] The thumb wrist-metacarpal joints of existing bionic hands mostly adopt a hard skeleton and a rigid shell. When contacting with light objects for grasping, the greater rigidity will generate greater pressure on the contact position between the object and the bionic hand, thereby causing wear on the object. Therefore, a thumb wrist-metacarpal joint of a bionic hand is proposed, which has the effect of buffering when grasping objects and improving the grasping strength when grasping heavier objects. Summary of the invention

[0004] In order to solve the problem that most of the background technologies proposed above use a hard skeleton and a rigid shell, which will cause greater pressure on the contact point between the object and the bionic hand due to its greater rigidity when grasping a light object, thereby causing wear to the object, the present invention provides a thumb wrist-metacarpal joint of a bionic hand.

[0005] A thumb carpometacarpal joint of a bionic hand comprises a buffer mechanism, a limiting mechanism is arranged above the buffer mechanism, a joint mechanism is arranged on the limiting mechanism, and the buffer mechanism and the limiting mechanism are both arranged inside the main body mechanism; The buffer mechanism includes a buffer pad, two piston rods are fixedly connected to the top of the buffer pad, a first spring is fixedly connected to the top of the piston rod, the piston rod is slidably connected to a fixed plate, a sealed cabin is provided on the top of the fixed plate, a vent is provided on the fixed plate, an airbag is fixedly connected to one side of the fixed plate, a double-sided rack is fixedly connected to the top of the buffer pad, and card slots are provided on both sides of the fixed plate.

[0006] Preferably, the double-sided rack passes through the bottom of the fixed plate and extends to the top of the fixed plate, the double-sided rack is located between the two piston rods, and the top of the piston rod passes through the bottom of the fixed plate and extends to the inside of the sealed cabin.

[0007] Preferably, the limiting mechanism includes two gears, the bottoms of the two gears are respectively meshed with transmission racks, the ends of the two transmission racks away from each other are slidably connected with telescopic rods, the ends of the telescopic rods away from the transmission racks are fixedly connected with the limiting rod, and the ends of the two limiting rods close to each other are provided with a plurality of tooth grooves.

[0008] Preferably, the plurality of tooth grooves are evenly distributed at one end of the two limit rods close to each other, the two gears are respectively meshed with the two sides of the double-sided rack, the two gears are symmetrically distributed with the double-sided rack as the center, the two telescopic rods are respectively located on both sides of the buffer pad, and the transmission rack is slidably connected to the fixed plate.

[0009] Preferably, the joint mechanism includes a wrist-palm joint, two limit frames are fixedly connected to both sides of the wrist-palm joint, a limit hole is opened on the wrist-palm joint, a plurality of elastic rubber blocks are fixedly connected inside the limit hole, triangular plates are rotatably connected to both sides of the wrist-palm joint, the sides of the two triangular plates close to each other are respectively slidably connected with clamping blocks, and the sides of the two clamping blocks away from each other are fixedly connected with a second spring.

[0010] Preferably, the two sides of the two clamping blocks that are away from each other are elastically connected to the inner walls of the two triangular plates through a second spring, and a plurality of elastic rubber blocks are evenly distributed inside the limiting hole, and the shape of the clamping block is an isosceles trapezoid.

[0011] Preferably, the size of the limiting rod is matched with the size of the limiting hole, the tooth groove is clamped with the elastic rubber block, and one end of the limiting rod close to the wrist-metacarpal joint passes through the limiting frame and extends to the inside of the limiting hole.

[0012] Preferably, the fixing plate is located between the two triangular plates, the size of the card slot is matched with the size of the card block, and the card slot and the card block are card-connected.

[0013] Preferably, the main mechanism includes a fixed frame, a sliding rod is fixedly connected to the fixed frame, a driving block is slidably connected to the sliding rod, connecting plates are rotatably connected on both sides of the driving block, the top of the fixed frame is fixedly connected to the bottom of the wrist-metacarpal joint, a proximal finger plate is rotatably connected to the side of the wrist-metacarpal joint away from the driving block, a distal finger plate is rotatably connected to the end of the proximal finger plate away from the wrist-metacarpal joint, an elastic pad is fixedly connected to the bottom of the distal finger plate, and a thumb shell is fixedly connected to the distal finger plate and the proximal finger plate.

[0014] Preferably, the bottom of the proximal finger plate is fixedly connected to the top of the fixed plate, a sealed cabin and a vent are provided at the bottom of the proximal finger plate, the vent and the airbag are communicated through the vent, the top of the piston rod is elastically connected to the inner wall of the sealed cabin through a first spring, and the gear is rotatably connected to the inner wall of the proximal finger plate.

[0015] Working principle and working process of the present invention: When grasping an object, the driving block first slides backward on the slide bar, and drives the triangle plate to rotate on the wrist-metacarpal joint through the connecting plate. The rotation of the wrist-metacarpal joint drives the proximal finger plate to rotate downward on the wrist-metacarpal joint through the connecting plate. After the bottom of the proximal finger plate contacts the object, the driving block continues to move and drives the distal finger plate to rotate downward through the connecting plate on the proximal finger plate, and finally the elastic pad at the bottom of the elastic pad grabs the object through the thumb shell. During the grasping process, the proximal finger plate will drive the telescopic rod to rotate around the limit frame, wherein the limit rod will adjust its length adaptively, and the buffer pad at the bottom of the proximal finger plate will first contact the object, and the continued rotation of the proximal finger plate will cause the piston rod to compress the first spring and squeeze the air inside the sealed cabin into the airbag through the vent hole, so that the airbag is filled and the thumb shell is fully fitted with the object; At the same time, the movement of the buffer pad toward the proximal finger plate will cause the double-sided rack to drive the two gears to rotate. The rotation of the gears will drive the two transmission racks to move toward each other, thereby driving the limit rod to move toward the wrist-metacarpal joint. When the top of the buffer pad is against the bottom of the fixed plate, the end of the limit rod close to the tooth groove will move into the limiting hole and engage with the elastic rubber block.

[0016] Beneficial effects of the present invention: The present invention solves the problem that when the device contacts an object, a large pressure is applied to the contact position between the object and the bionic hand due to the large rigidity, thereby causing wear to the object. During the grasping process, the buffer pad at the bottom of the proximal finger plate will first contact the object, and the continued rotation of the proximal finger plate will cause the piston rod to squeeze the first spring and the air inside the sealed cabin. The force applied by the proximal finger plate to the buffer pad and the surface of the object is buffered by the air pressure inside the sealed cabin and the elastic force of the first spring. At the same time, the air inside one of the sealed cabins will squeeze the inside of the airbag through the vent hole to fill the airbag, so that the thumb shell and the object are fully fitted, the contact area and the flexible area are increased, and the stability of grasping is improved. At the same time, the buffer mechanism can be arranged to deform and absorb energy when the device is under pressure, reduce the impact on the wrist-metacarpal joint, and indirectly increase the service life of the device. The present invention improves the strength of the device for grabbing heavier objects by arranging the cooperation of structures such as a limit rod and an elastic rubber block. When the buffer pad moves in the direction close to the proximal finger plate, the double-sided rack drives the two gears to rotate. The rotation of the gears drives the two transmission racks to move in the direction close to each other, thereby driving the limit rod to move in the direction close to the wrist-metacarpal joint. When the top of the buffer pad abuts against the bottom of the fixed plate (that is, when grabbing heavier objects), the end of the limit rod close to the tooth groove moves to the inside of the limit hole and engages with the elastic rubber block. The high friction force increases the resistance of the limit rod to rotate in the limit hole, thereby increasing the resistance of the proximal finger plate to rotate in the direction of release when the device grabs heavier objects, thereby improving the grabbing strength and stability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of an embodiment of the present invention; Figure 2 It is a schematic diagram of the three-dimensional structure of the main mechanism of an embodiment of the present invention; Figure 3 It is a schematic diagram of the side structure of the main mechanism of an embodiment of the present invention; Figure 4 is a schematic cross-sectional structure diagram of a proximal fingerboard according to an embodiment of the present invention; Figure 5 A schematic diagram of the structural relationship between the clamp block and the triangular plate according to an embodiment of the present invention; Figure 6 A schematic diagram of the structural relationship between the limiting rod and the limiting frame according to an embodiment of the present invention; Figure 7 It is a schematic diagram of the three-dimensional structure of the buffer mechanism according to an embodiment of the present invention; Figure 8 The figure is a schematic diagram of the structural relationship between the card block and the card slot according to an embodiment of the present invention.

[0018] In the figure: 1. Buffer mechanism; 101. Buffer pad; 102. Piston rod; 103. Fixed plate; 104. Sealed cabin; 105. First spring; 106. Vent hole; 107. Airbag; 108. Double-sided rack; 109. Slot; 2. Limiting mechanism; 201. Gear; 202. Transmission rack; 203. Telescopic rod; 204. Limiting rod; 205. Tooth groove; 3. Joint mechanism; 301. Carpal joint; 302. Limiting frame; 303. Limiting hole; 304. Elastic rubber block; 305. Triangular plate; 306. Slot; 307. Second spring; 4. Main body mechanism; 401. Fixed frame; 402. Sliding rod; 403. Driving block; 404. Proximal finger plate; 405. Thumb shell; 406. Distal finger plate; 407. Elastic pad; 408. Connecting plate. DETAILED DESCRIPTION

[0019] See also Figures 1 to 8 Shown is an embodiment of the present invention.

[0020] A thumb carpometacarpal joint of a bionic hand comprises a buffer mechanism 1, a limiting mechanism 2 is arranged above the buffer mechanism 1, a joint mechanism 3 is arranged on the limiting mechanism 2, and the buffer mechanism 1 and the limiting mechanism 2 are both arranged inside a main body mechanism 4; The buffer mechanism 1 includes a buffer pad 101, two piston rods 102 are fixedly connected to the top of the buffer pad 101, a first spring 105 is fixedly connected to the top of the piston rod 102, the piston rod 102 is slidably connected to a fixed plate 103, a sealed cabin 104 is provided on the top of the fixed plate 103, a vent hole 106 is provided on the fixed plate 103, an airbag 107 is fixedly connected to one side of the fixed plate 103, a double-sided rack 108 is fixedly connected to the top of the buffer pad 101, and slots 109 are provided on both sides of the fixed plate 103.

[0021] The double-sided rack 108 passes through the bottom of the fixing plate 103 and extends to the top of the fixing plate 103 . The double-sided rack 108 is located between the two piston rods 102 . The top of the piston rod 102 passes through the bottom of the fixing plate 103 and extends to the inside of the sealed cabin 104 .

[0022] By arranging the cooperation of structures such as the buffer pad 101 and the piston rod 102, the problem of causing wear to the object due to the large rigidity of the device when in contact with the object is solved. During the grasping process, the buffer pad 101 located at the bottom of the proximal finger plate 404 will first contact the object, and the continued rotation of the proximal finger plate 404 will cause the piston rod 102 to squeeze the first spring 105 and squeeze the air inside the sealed cabin 104. The force applied by the proximal finger plate 404 to the buffer pad 101 and the surface of the object is buffered by the internal air pressure of the sealed cabin 104 and the elastic force of the first spring 105. At the same time, the air inside one of the sealed cabins 104 will squeeze the inside of the airbag 107 through the vent 106 to fill the airbag 107, so that the thumb shell 405 is fully fitted with the object, the contact area and the flexible area are increased, and the stability of grasping is improved. At the same time, the buffer mechanism 1 is provided to deform and absorb energy when the device is under pressure, reduce the impact on the wrist-metacarpal joint 301, and indirectly increase the service life of the device.

[0023] like Figures 2 to 8 As shown, the limiting mechanism 2 includes two gears 201, and the bottoms of the two gears 201 are respectively meshed with transmission racks 202, and the ends of the two transmission racks 202 that are away from each other are slidably connected with telescopic rods 203, and the ends of the telescopic rods 203 that are away from the transmission racks 202 are fixedly connected with the limiting rod 204, and the ends of the two limiting rods 204 that are close to each other are provided with a plurality of tooth grooves 205.

[0024] A plurality of tooth grooves 205 are evenly distributed at one end of the two limit rods 204 close to each other, the two gears 201 are respectively meshed with the two sides of the double-sided rack 108, the two gears 201 are symmetrically distributed with the double-sided rack 108 as the center, the two telescopic rods 203 are respectively located on both sides of the buffer pad 101, and the transmission rack 202 is slidably connected to the fixed plate 103.

[0025] The joint mechanism 3 includes a wrist-metacarpal joint 301, and two limit frames 302 are fixedly connected on both sides of the wrist-metacarpal joint 301. A limit hole 303 is opened on the wrist-metacarpal joint 301, and a plurality of elastic rubber blocks 304 are fixedly connected inside the limit hole 303. Triangular plates 305 are rotatably connected on both sides of the wrist-metacarpal joint 301, and the sides of the two triangular plates 305 that are close to each other are respectively slidably connected with a clamping block 306, and the sides of the two clamping blocks 306 that are away from each other are fixedly connected with a second spring 307.

[0026] The size of the limiting rod 204 matches that of the limiting hole 303 , the tooth groove 205 is clamped with the elastic rubber block 304 , and one end of the limiting rod 204 close to the carpometacarpal joint 301 passes through the limiting frame 302 and extends to the inside of the limiting hole 303 .

[0027] By setting up the coordination of structures such as the limit rod 204 and the elastic rubber block 304, the strength of the device in grasping heavier objects is improved. When the buffer pad 101 moves toward the direction close to the proximal finger plate 404, the double-sided rack 108 will drive the two gears 201 to rotate, and the rotation of the gear 201 will drive the two transmission racks 202 to move toward each other, thereby driving the limit rod 204 to move toward the wrist metacarpal joint 301. When the top of the buffer pad 101 is against the bottom of the fixed plate 103 (that is, when grasping heavier objects), the end of the limit rod 204 close to the tooth groove 205 will move into the limit hole 303 and engage with the elastic rubber block 304. The resistance of the limit rod 204 to rotate in the limit hole 303 is increased through high friction, thereby increasing the resistance of the proximal finger plate 404 to rotate in the release direction when the device grasps heavier objects, thereby improving the grasping strength and stability of the device.

[0028] like Figures 1 to 6 As shown, the sides of the two blocks 306 that are away from each other are elastically connected to the inner walls of the two triangular plates 305 through the second spring 307, and a number of elastic rubber blocks 304 are evenly distributed inside the limiting hole 303. The shape of the block 306 is an isosceles trapezoid. The fixing plate 103 is located between the two triangular plates 305. The size of the slot 109 is adapted to the size of the block 306, and the slot 109 and the block 306 are clamped together.

[0029] The main mechanism 4 includes a fixed frame 401, to which a slide bar 402 is fixedly connected, to which a driving block 403 is slidably connected, and connecting plates 408 are rotatably connected on both sides of the driving block 403. The top of the fixed frame 401 is fixedly connected to the bottom of the wrist-metacarpal joint 301, and a proximal finger plate 404 is rotatably connected to the side of the wrist-metacarpal joint 301 away from the driving block 403, and a distal finger plate 406 is rotatably connected to the end of the proximal finger plate 404 away from the wrist-metacarpal joint 301, and an elastic pad 407 is fixedly connected to the bottom of the distal finger plate 406, and a thumb shell 405 is fixedly connected to the distal finger plate 406 and the proximal finger plate 404.

[0030] The bottom of the proximal finger plate 404 is fixedly connected to the top of the fixed plate 103, and a sealed cabin 104 and a vent 106 are provided at the bottom of the proximal finger plate 404. The vent 106 and the airbag 107 are connected via the vent 106. The top of the piston rod 102 is elastically connected to the inner wall of the sealed cabin 104 via the first spring 105, and the gear 201 is rotationally connected to the inner wall of the proximal finger plate 404. The thumb housing 405 is made of elastic material.

[0031] By making the driving block 403 slide backward on the slide bar 402, the triangle plate 305 is driven to rotate on the wrist-metacarpal joint 301 through the connecting plate 408. The rotation of the wrist-metacarpal joint 301 drives the proximal finger plate 404 to rotate downward on the wrist-metacarpal joint 301 through the connecting plate 408. After the bottom of the proximal finger plate 404 hits the object, the driving block 403 continues to move and drives the distal finger plate 406 to rotate downward through the connecting plate 408 on the proximal finger plate 404, and finally the elastic pad 407 at the bottom of the elastic pad 407 grabs the object through the thumb shell 405. The elastic thumb shell 405, the elastic pad 407 and the buffer pad 101 are arranged to make the device fit the human thumb more closely.

[0032] The working principle and working process of this embodiment: When grabbing an object, the driving block 403 first slides backward on the slide bar 402, and drives the triangle plate 305 to rotate on the wrist-metacarpal joint 301 through the connecting plate 408. The rotation of the wrist-metacarpal joint 301 drives the proximal finger plate 404 to rotate downward on the wrist-metacarpal joint 301 through the connecting plate 408. After the bottom of the proximal finger plate 404 hits the object, the driving block 403 continues to move and drives the distal finger plate 406 to rotate downward through the connecting plate 408 on the proximal finger plate 404, and finally the elastic pad 407 at the bottom of the elastic pad 407 grabs the object through the thumb housing 405. During the grasping process, the proximal finger plate 404 will drive the telescopic rod 203 to rotate around the limiting frame 302, wherein the limiting rod 204 will adjust its length adaptively, and the buffer pad 101 at the bottom of the proximal finger plate 404 will first contact the object, and the proximal finger plate 404 will continue to rotate to cause the piston rod 102 to squeeze the first spring 105 and squeeze the air inside the sealed cabin 104 into the airbag 107 through the vent 106, so that the airbag 107 is filled and the thumb housing 405 is fully fitted with the object; At the same time, the movement of the buffer pad 101 toward the proximal finger plate 404 will cause the double-sided rack 108 to drive the two gears 201 to rotate, and the rotation of the gear 201 will drive the two transmission racks 202 to move toward each other, thereby driving the limit rod 204 to move toward the carpometacarpal joint 301. When the top of the buffer pad 101 is against the bottom of the fixing plate 103, the end of the limit rod 204 close to the tooth groove 205 will move to the inside of the limit hole 303 and engage with the elastic rubber block 304.

Claims

1. A thumb carpometacarpal joint of a bionic hand, comprising a buffer mechanism (1), characterized in that: A limiting mechanism (2) is arranged above the buffer mechanism (1), a joint mechanism (3) is arranged on the limiting mechanism (2), and both the buffer mechanism (1) and the limiting mechanism (2) are arranged inside the main body mechanism (4); The buffer mechanism (1) comprises a buffer pad (101), the top of the buffer pad (101) is fixedly connected to two piston rods (102), the top of the piston rod (102) is fixedly connected to a first spring (105), the piston rod (102) is slidably connected to a fixed plate (103), the top of the fixed plate (103) is provided with a sealed cabin (104), the fixed plate (103) is provided with a vent hole (106), one side of the fixed plate (103) is fixedly connected to an air bag (107), the top of the buffer pad (101) is fixedly connected to a double-sided rack (108), and both sides of the fixed plate (103) are provided with a card slot (109).

2. The thumb carpometacarpal joint of a bionic hand according to claim 1, characterized in that: The double-sided rack (108) passes through the bottom of the fixed plate (103) and extends to the top of the fixed plate (103). The double-sided rack (108) is located between the two piston rods (102). The top of the piston rod (102) passes through the bottom of the fixed plate (103) and extends to the inside of the sealed cabin (104).

3. The thumb carpometacarpal joint of a bionic hand according to claim 1, characterized in that: The limiting mechanism (2) comprises two gears (201), the bottoms of the two gears (201) are respectively meshed with transmission racks (202), the ends of the two transmission racks (202) away from each other are slidably connected to telescopic rods (203), the ends of the telescopic rods (203) away from the transmission racks (202) are fixedly connected to the limiting rod (204), and the ends of the two limiting rods (204) close to each other are each provided with a plurality of tooth grooves (205).

4. The thumb carpometacarpal joint of a bionic hand according to claim 3, characterized in that: The plurality of tooth grooves (205) are evenly distributed at one end of the two limit rods (204) close to each other, the two gears (201) are respectively meshed with the two sides of the double-sided rack (108), the two gears (201) are respectively symmetrically distributed with the double-sided rack (108) as the center, the two telescopic rods (203) are respectively located at the two sides of the buffer pad (101), and the transmission rack (202) is slidably connected to the fixed plate (103).

5. The thumb carpometacarpal joint of a bionic hand according to claim 3, characterized in that: The joint mechanism (3) comprises a wrist-palm joint (301), two limiting frames (302) are fixedly connected to both sides of the wrist-palm joint (301), a limiting hole (303) is provided on the wrist-palm joint (301), a plurality of elastic rubber blocks (304) are fixedly connected inside the limiting hole (303), triangular plates (305) are rotatably connected to both sides of the wrist-palm joint (301), a clamping block (306) is slidably connected to the sides of the two triangular plates (305) that are close to each other, and a second spring (307) is fixedly connected to the sides of the two clamping blocks (306) that are away from each other.

6. The thumb carpometacarpal joint of a bionic hand according to claim 5, characterized in that: The two sides of the two clamping blocks (306) that are away from each other are elastically connected to the inner walls of the two triangular plates (305) via the second spring (307), and a plurality of elastic rubber blocks (304) are evenly distributed inside the limiting hole (303).

7. The thumb carpometacarpal joint of a bionic hand according to claim 5, characterized in that: The size of the limiting rod (204) is matched with the size of the limiting hole (303), the tooth groove (205) is clamped with the elastic rubber block (304), and one end of the limiting rod (204) close to the wrist-metacarpal joint (301) passes through the limiting frame (302) and extends to the inside of the limiting hole (303).

8. The thumb carpometacarpal joint of a bionic hand according to claim 5, characterized in that: The fixing plate (103) is located between the two triangular plates (305), the size of the clamping slot (109) matches the size of the clamping block (306), and the clamping slot (109) and the clamping block (306) are clamped together.

9. The thumb carpometacarpal joint of a bionic hand according to claim 5, characterized in that: The main body mechanism (4) comprises a fixed frame (401), a sliding rod (402) is fixedly connected to the fixed frame (401), a driving block (403) is slidably connected to the sliding rod (402), both sides of the driving block (403) are rotatably connected to connecting plates (408), the top of the fixed frame (401) is fixedly connected to the bottom of the carpometacarpal joint (301), a side of the carpometacarpal joint (301) away from the driving block (403) is rotatably connected to a proximal finger plate (404), an end of the proximal finger plate (404) away from the carpometacarpal joint (301) is rotatably connected to a distal finger plate (406), an elastic pad (407) is fixedly connected to the bottom of the distal finger plate (406), and a thumb shell (405) is fixedly connected to the distal finger plate (406) and the proximal finger plate (404).

10. The thumb carpometacarpal joint of a bionic hand according to claim 9, characterized in that: The bottom of the proximal finger plate (404) is fixedly connected to the top of the fixed plate (103), and a sealed cabin (104) and a vent (106) are provided at the bottom of the proximal finger plate (404). The vent (106) and the airbag (107) are connected via the vent (106). The top of the piston rod (102) is elastically connected to the inner wall of the sealed cabin (104) via the first spring (105), and the gear (201) is rotationally connected to the inner wall of the proximal finger plate (404).

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