US2598593A - Polycentric articulated finger for artificial hands - Google Patents

Description

L. J. PARKER 2,598,593

2 swam-swam 1 POLYCENTRIC ARTICULATED FINGER FOR ARTIFICIAL HANDS INVENTOR LINUS J. PARKER flue-L Ki wa AGENT May 27, 1952 Filed Sept. 30, 1948 May 27, 1952 PARKER 4 2,598,593

POLYCENTRIC ARTICULATED FINGER F'QR ARTIFICIAL HANDS Filed Sept. 50, 1948 j 2 SHEETS-SHEET 2 VENTOR LIN J. PARKER BY c M 3.0mm

AGENT Patented May 27, 1952 UNITED STATES ATENT OFFICE POLYCENTRIC ARTICULATED FINGER FOR ARTIFICIAL HANDS Linus J. Parker, Windsor, N. Y., assignor to International Business Machines Corporation,

6 Claims.

The improved polycentric articulated finger comprising the present invention has been designed primarily for use in connection with the hand section of the electrically driven artificial arm.

The, articulated finger is, however, capable of being employed in connection with other types of artificial hands and when so employed any one of the five fingers of the hand, with the exception of the thumb, may embody the principles of the present invention.

It is among the principal objects of the present invention to provide an articulated finger comprising a proximal segment, a medial segment and a distal or tip segment, which segments are formed by a moulding process with the proximal and distal segments having concave ends, while the medial segment is provided With matching convex ends. The segments are hingedly secured together so as to be capable of rolling around on each other, so to speak, while a relatively constant and small separation line is maintained between the segments.

In carrying out the invention, the joints between the segments are formed by male projections on the proximal and distal segments which Work smoothly within the female ends of the medial segment. Thus ample resistance to side thrust is given by the material itself minimizing the stresses upon the bearings. The segments are joined by steel bushings which make a running fit with the outer walls of the segments by forming a pressed fit with the inner walls or projections. The material of the various segments is preferably mouldable nylon on account of the strength and durability of the latter and also because of the ease with which the material may be tinted to resemble the color of human flesh. Articulation is produced by a combination of a lever linkage and a pair of mating gear sectors which span the medial joint. These gears are out directly in the nylon projections of the proximal and distal segments. The articulations of the finger segments are related to the flexion of the proximal joint by a steel bracket which is attached to the frame of the hand section. When the proximal segment is flexed a pivoted linkage acting between the bracket and the medial segments forces the latter to rotate with respect to the proximal segment. This rotation carries a gear sector on the distal segment around a gear sector on the proximal segment, thus causing the distal segment or tip of the finger to curl inward at a uniform rate with the entire finger closely simulating-the normal curling action of a natural finger.

Other objects or the invention will be pointed out in the following description and claims and illustrated in the accompanyin drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a side elevational view of an articulated finger constructed in accordance with the principles of the present invention. This view is somewhat diagrammatic in its representation and illustrates an extended and a retracted or curled position of the finger.

Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1 in the direction indicated by the arrows.

Fig. 3 is a sectional view taken substantially along the line 33 of Fig. 2.

Fig. 4 is a sectional View taken substantially along the line 4--4 of Fig. 3.

Fig. 5 is a sectional view taken substantially along the line 55 of Fig. 2.

Fig. 6 is a sectional view taken substantially along the line 6-6 of Fig. 2.

In all of the above described views like characters of reference are employed to designate like parts throughout.

Referring now to the drawings in detail, the articulated finger involves in its general organization a proximal segment ill, a medial segment l2, and a distal or tip segment I4, each of these segments being formed by a moulding process, the material preferably being nylon on account of the ruggedness and durability of the latter and the fact that the same may readily be colored to simulate the natural appearance of the human hand by a dyeing process.

The proximal segment in is in the form of a hollow shell having a generally rounded end l6 Which is adapted to fit snugly Within a recess provided in the shell I! of the hand section of the artificial arm (not shown). The segment I0 is provided with a pair of inwardly extending hub portions I8 and 28 (Figs. 2 and 3) through which there projects a stainless steel pivot pin 22, which pin may form the common pivotal support for a series of the articulated fingers, only one such finger being shown in the drawings. The pin 22 has its end suitably supported in a portion (not shown) of the frame 23 of the hand section of the artificial arm. A metal hub 24 surrounds the pin 22 between the hubs l8 and 20 and is integrally formed with an attachment bracket 26 which projects through a slot 28 provided in the end It of the segment I0 and which is provided with a laterally turned end 33 having an attachment hole or opening 3!! formed therein designed for reception of an attachment screw 29, by means of which the bracket 25 is fixedly secured to the frame 23 of the hand section of the artificial arm.

The segment ID is formed at its outer end with a centrally disposed gear sector 32 having a series of gear teeth 34 (Figs. 2 and 3) formed thereon. The sides of the shell of which the segment I0 is formed, are cut away as at 36 on opposite sides of the gear sector 32, these cut-away portions being of arcuate configuration to permit nesting 3 of the innerend of thefinger segment I2 within the outer end of the segment [0. The segment I2 is provided with a pair of internal hub portions 38 and 40 through which there extends a hollow tubular pintle pin 42' which extends other end of the link being pivotally secured to.

the segment 12 by means of a pin Eiii which. project's through a curved slot 52 formed in the gear sector 32' and which has its ends extending into.

and secured in the sides of the shell of which. the

segment i2 is formed. The internal hub portion iil'of the finger segment i2v is cut away as at 55 V to' provide a clearance for the pin 53 andv the end of the. link 43. V The distal. or tip segment. I4

is provided with a centrall disposed gear. sector M EBhaving a series of teeth 58'formed' thereon designed for meshing engagement with. the teeth 34 of the gear sector 32. The inner end. of the sides of the shell of which the hollow finger segment is is formed is cut away as at 6?! on opposite sides of the sector as to permit. the curved. outer endof the finger segment l2 to be nested: within the innerend of the shell of the segment is. A hollow pintle pin 62' has its ends secured in the sides of the shell of the segment I? and passes through an opening 84' formed. in the gear sector E E. A pair of nylon plugs 86, similar to the plugs 44', seal the ends of the hollow pintle pin 62.

It will be seen from'the above description of parts that because the outer end of the link 68 is secured tothe' sides of the. shell of the finger segment [2 at a point which is eccentrically disposed with respect to the pintle pin 42, counterclockwise rotational movement of the finger. segment i9 relative to the. fixed bracket 28, as shown in Fig. 3, will apply a torque to the finger segirier 2 tending to cause this latter segment to move relative to the segment H3 in a counterclockwise direction. This phenomenon of mutual interdependency of movement between the two segments i8 and 2 exists by virtue of the fact that while the distance between the axes of the pintle pins 22 and' ii remains the same dur ing swinging movement of the finger segment It, the distance between the axis of the pintie pin 22 and the axisof the pivot pin 59 becomes shorter. This latter pivot pin efl, being eccentric with respect to the pintlepin 52, will cause the link 38 to exert a pulling torque on the shell of the finger segment #2 to decrease the angle between the longitudinal axes of the two segments H3 and i2 direct proportion to the extent of pivotal movement of the segment i 0 about the axis of the bracket 25. Because of. the fact that the distance between theaxes'of the pintle pins 12 and 51? remains constant, tilting movement of thesegmen-t l2 relative to-thesegment to in a counterclockwise direction, as viewed in Fig. 2, will cause the gear sector 55 to roll on the gear sector 32, thus moving the segment it about the axis of the pintle pin ea in 'a counter-clockwise direction relative to the segment 12, so that the three finger segments Hi, i2 and I4 assume a progressive curling action as illustrated by the dotted line configuration of these segments.

The gear sectors 56 and-32 are'received in the slotted ends of the medial segment !2 by a frictional fit, the coefiicient of friction of the nylon material and the surface pressures involved being designed according to engineering exigencies in such" amanner that the various segments are not. loose uponeach other nor are they so tight that the amputee is unable by the use of his natural' hand to preposition the articulated finger to any desired angular relationship of which the various segments are capable.

From the above description of parts it will be seen that an articulated finger has been design d in which there areno protruding levers. linkages or. open slots. The. usual 60 fiexion required at the first finger joint has been split into-two. adjacent. 30 fiexions, thus allowing the. provision of a finger with smooth contours and which is free of open seams and exposed joints.

Although the cosmetic appearance of the nylon.

material is such that a cosmetic glove is notrequired, the amputee may, if he desires, wear a cosmetic glove and in such an instance the compression and extension required of the cosmetic glove is 'very materially reduced.

While there have been shown and described and pointed out the fundamental novel features of the invention. as applied to a preferred, embodiment, it will be understood that various.

omissions and substitutions and changes in the form and details of the apparatus illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What. is claimed is: 1. In an artificial hand, a frame, an articulated finger including a proximal segment, a ,edial segment and a distal segment, means operatively pivotally connecting said proximal segto said frame, means pivotally connecting said proximal segment to said. medial segment, means pivotally connecting said. medial segment to said distal segment, a gear sector fixedly carried by said proximal segment and projecting. into said medial segment, a second gear sector fixedly carried by said distal. segment and likewise projecting into said medial segment and meshing with saidfirst mentioned gear sector, and a link having one end. operatively pivotally: connected to said frame at a point eccentric of the connection of said. proximal segment to said frame and the other end thereof pivotally con nected to said medial segment at a point on the latter eccentr cally disposed with respect to the pivotal. axis of connection between proximal se ment and said medial segment.

2. In an artificial hand, a frame, an articulated finger including a proximal segment, a medial segment and a distal segment, means operatively pivotally connecting said proximal segment to said frame, means pivotally connecting said proximal segment to said medial'segment, means pivotally connecting said medial segment to distal segment, a gear sector fixedly carried by said proximal segment and projecting into said medial segment, a second gear sector fixedly carried by said distal segment and likewise projecting into said medial segment and meshing with said first mentioned gear sector, and a link having one end operatively pivotally connected to said frame at a point eccentric of the connection of said proximal segment to said frame and the other end thereof pivotally connected to said medial segment at a point on the latter eccentrically disposed with respect to the pivotal axis of connection between said proximal segment and said medial segment.

3. In an artificial hand having a frame, an articulated finger for said hand including a proximal segment, a medial segment and a distal segment, means operatively pivotally connecting said proximal segment to said frame, means pivotally connecting said proximal segment to said medial segment, means pivotally connecting said medial segment to said distal segment, said segments each being formed of moldable material, a gear sector integrally formed on said proximal segment, a second gear sector integrally formed on said distal segment, said medial segment being of hollow shell-like configuration and said gear sectors projecting into said medial segment and meshing with each other interiorly thereof, and a link operatively pivotally connected at one end to said frame at a point eccentric to the connection of said proximal segment to said frame and at the other end to said medial segment at a point eccentrically disposed with respect to the pivotal axis of connection between said proximal segment and said medial segment whereby pivotal movement of said proximal segment relative to said frame will cause pivotal movement of the medial segment relative to the proximal segment.

4. In an artificial hand having a frame, an articulated finger for said hand including a proximal segment, a medial segment and a distal segment, means operatively pivotally connecting said proximal segment to said frame, means pivotally connecting said proximal segment to said medial segment, means pivotally connecting said medial segment to said distal segment, a gear sector integrally formed on said proximal segment, a second gear sector integrally formed on said distal segment, said medial segment being of hollow shell-like configuration and said gear sectors projecting into said medial segment and meshing with each other interiorly thereof, and a link operatively pivotally connected at one end to said frame at a point eccentric to the connection of said proximal segment to said frame at a point removed from the pivotal axis between said proximal segment and the frame and at the other end to said medial segment at a point eccentrically disposed with respect to the pivotal axis of connection between said proximal segment and said medial segment whereby pivotal movement of said proximal segment relative to said frame will cause pivotal movement of the medial segment relative to the proximal segment and pivoted movement of the distal segment relative to the medial segment.

5. In an artificial hand including a frame, an articulated finger for said hand comprising a proximal segment, a medial segment and a distal segment, said proximal and medial segments each being in the form of a hollow shell, means operatively pivotally connecting said proximal segment to said frame, means pivotally connecting said proximal segment to said medial segment, means pivotally connecting said medial segment to said distal segment, a link having one end pivoted to said frame and the other end operatively pivotally connected to said medial segment about an axis eccentrically disposed with respect tothe axis of pivotal connection between said proximal and medial segments, the effective length of said link being shorter than 6 the distance between the pivotal axis existing between said proximal segment and the framework and the pivotal axis existing between the proximal segment and the medial segment whereby swinging movement of said proximal segment relative to the framework will effect swinging movement of the medial segment with respect to said proximal segment, a gear sector fixedly carried by said proximal segment, a second gear sector fixedly carried by said distal segment, said gear sectors projecting into said medial segment and meshing with each other whereby swinging movement of said medial segment with respect to said proximal segment will cause swinging movement of said distal segment with respect to said medial segment thereby effecting a curling or an uncurling action of the articulated finger, as the case may be.

6. In an artificial hand including a frame, an articulated finger for said hand comprising a proximal segment, a medial segment and a distal segment, said proximal and medial segments each being of hollow shell-like configuration, means operatively pivotally connecting said proximal segment to said frame, means pivotally connecting said proximal segment to said medial segment, means pivotally connecting said medial segment to said distal segment, the opposite ends of said medial segment being generally of convex arcuate configuration and each being provided with a transverse slot therein, the outer end of said proximal segment being generally of concave arcuate configuration with the adjacent end of said medial segment nesting therein with sufficient clearance being provided for relative pivotal movements between said two latter segments, the inner end of said distal segment being generally of concave arcuate configuration with the outer end of said medial segment nesting therein with sufficient clearance being provided to permit relative movements between said medial and distal segments, a gear sector integrally formed on said proximal segment and projecting into one of said transverse slots, a second gear sector integrally formed on said distal segment and projecting into the other transverse slot, said gear sectors meshing with each other inside of said medial segments with the sides of said gear sectors frictionally engaging the edges of their respective slots to yieldably hold said segments in predetermined relative positions of angularity with respect to each other, a link operatively pivotally connected at one end to said frame about an axis removed from the axis of pivotal connection between said proximal segment and the frame and at the other end to said medial segment about an axis removed from the axis of pivotal connection between said proximal segment and said medial segment, the effective length of said link being less than the distance between the pivotal axis between said proximal segment and frame and the pivotal axis between said proximal segment and said medial segment.

LINUS J. PARKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,285,617 Caron Nov. 26, 1918 1,507,681 Pecorella et al Sept. 9, 1924

Images