US3521303A

US3521303A - Artificial hand for prostheses with bioelectrical control

Info

Publication number: US3521303A
Application number: US652881A
Authority: US
Inventors: Yakov Savelievich Yakobson; Vitaly Moiseevich Bernshtein; Efim Pinkhasovich Polyan
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-07-12
Filing date: 1967-07-12
Publication date: 1970-07-21
Anticipated expiration: 1987-07-21

Description

July 21, 1970 Y. s. YAKOBSON ETAL 3,521,303

ARTIFICIAL HAND FOR PROSTHESES WITH BIOELECTRICAL CONTROL Filed July 12, 1967 United States Patent 3,521,303 ARTIFICIAL HAND FOR PROSTHESES WITH BIOELECTRICAL CONTROL Yakov Savelievich Yakobson, 2 Neglinny pereulok 5, kv. 8; Vitaly Moiseevich Bernshtein, Ulitsa Vavilova 36, korpus 4, kv. 48; and Efim Pinkhasovich Polyan, Ulitsa Morisa Toreza 26/1, kv. 469, all of Moscow, USSR.

Filed July 12, 1967, Ser. No. 652,881 Int. Cl. A61f l/06 U.S. Cl. 3-1.1 3 Claims ABSTRACT OF THE DISCLOSURE An artificial hand comprises a lever-joint unit for the thumb having two degrees of freedom and a lever-joint system for the remaining four fingers constituted by individual levers articulated in pairs respectively driven by a pair of rocker units in turn connected with acommon control rocker which is driven from a drive unit. An independent drive unit operates the thumb unit in pivotal extension, whereas a further drive unit serves for turning of the thumb unit with respect to its axis.

The invention relates to upper extremity prostheses with bio-electrical control; additionally, it can find application in manipulators.

Artificial hands to prostheses with bio-electrical control which are in use heretofore are incapable of affording diverse kinds of hand grip corresponding to the functions of a natural human hand, and said hands are not capable of performing motorial functions when manipulation with every particular finger is involved.-

For example, there exists an artificial hand for a bioelectrically controlled prosthesis, wherein movements of all five fingers are in a permanent operative connection to one another. A disadvantage of said hand resides in that it is capable of only a grip with the fingertips (finger-pinch) An object of the present invention is to eliminate aforesaid and other disadvantages.

A specific object of the present invention is to provide an artificial hand which is capable of performing diverse kinds of grip of various shaped objects, as well as of micromotorial functions when motion of each individual finger is required.

Said object is accomplished by the application of individual drives actuating the thumb and the cluster of four longer fingers, a differential rocker mechanism, a mechanism for transferring the thumb from opposition to abduction, a system of elastic links or flexible ties running to each finger, a device for automatic flexion of the ungual phalanx of the thumb.

According to the invention, provision is made in the artificial hand proposed here and below, for individual and independently functioning control lines actuating the thumb unit which is capable of motion with two directions of movement, and actuating the remaining four fingers, each of said control lines incorporating an independent reversible electric drive which is controlled by biological currents taken off truncated muscles and is operatively associated with a lever-joint system imitating the phalanges of the four longer fingers, and with an independent lever-joint unit of the thumb.

The thumb unit is preferably made as an individual articulated lever, whereas the pivotally mounted phalanges of the remaining fingers are articulated in pairs to two pivoted rocker arms of the differential rocker mechanism, the midpoints of said rocker arms being articulated to a common control (master) rocker.

The aforesaid independent electric drives can incorporate micromotors provided with self-braking screw gears, one of said micromotors imparting motion to said master rocker of the four-finger cluster while the other is coupled to the lever of the thumb.

It is likewise expedient that the pivot pins of the levers which imitate the main phalanges of the fingers, be oriented with respect to one another at some angle corresponding to those inherent in a natural human hand, whereas the levers are advantageous to be connected to the differential rocker mechanism through a ball-andsocket joint.

The unit of the thumb can be provided with a mechanism for an additional passive turning of said finger with respect to an axis perpendicular to the axis of flexionextension thereof, an automatic spring-actuated locking of the finger in position being also provided.

The ungual phalanx of the thumb can be made as a spring-loaded rocker movable at an interphalangeal articulated joint.

An embodiment of the present invention is described hereinbelow by way of example with reference to the appended drawing, wherein the sole figure thereof shows a schematic functional diagram of the artificial hand of the invention.

Referring to the drawing, the artificial hand comprises a frame containing a drive 1 actuating a four-finger cluster 2, a differential rocker mechanism 3, a drive 4 actuating a thumb 5, a mechanism 6 for passive abduction of the thumb, a unit 7 of passiverotation, elastic links 8, and an articulated joint 9 whereby the ungual phalanx of the thumb 5 is flexed.

The longer fingers 2 of the hand can be flexed at the metacarpophalangeal and proximal interphalangeal articulated joints thereof, whereby a first grip is rendered possible. The motion of each finger at the aforesaid joints is operatively associated with that of the other fingers. A fingertip grip occurs when the thumb 5 is in opposition to the second and third ones. This being the case, the fourth and fifth fingers are forced towards the palm, whereby the process of writing becomes more convenient.

The differential rocker mechanism 3 makes it possible for each longer finger 2 to be adapted for the shape of every particular object to be gripped.

The pivot pins of the metacarpophalangeal joints of the longer fingers 2 are arranged at certain angles corresponding in those inherent to a natural human hand, whereby the artificial hand appears more cosmetical, a strong grip of diversely shaped objects is attained, writing is made more convenient due to shifting of the fourth and fifth fingers towards the center line of the palm, the frames of the fingers 2 being connected to the rocker mechanism 3 through ball-and-socket joints 10.

To make the motion of the longer fingers 2 more regular, as well as to provide for motion of some fingers with the other ones pressed to the palm, use is made of the elastic links 8 which are in effect springs and are held with one of their ends to every particular finger, and with the other end, to the body of the palm, said springs generating moments of flexure increasing sequentially from the third finger to the fifth one.

The abovesaid fact makes it possible to effect micromotions either with the second (index) finger or with the second and third fingers at a time, with the fourth and fifth fingers clenched to the palm. So the design of the hand proposed here and below provides for gripping of an object with the two or three fingers, allows operating calculating machines or typewriters with the index finger, makes it possible for said finger to pull at the trigger of a pistol or electric drill, with the other fingers firmly clenching the instrument handle.

The principal motion performed by the thumb 5 is effected in the direction of flexion-extension with respect to an articulated joint 11 located in the area corresponding to the carpometacarpal joint of a human hand. The fiexion-extension axis of the artificial hand is arranged similarly to that of a natural human hand when a fingertip or fist grip occurs. To effect a side grip, provision is made for a second degree of freedom of motion in the direction of abduction-opposition, whereby a passive rotation of the thumb 5 is allowed with respect to an axis perpendicular to the axis of fiexion-extension of that finger, with an automatic spring-locking of the finger 5 in a few positions. The side grip is of importance especially when performing various everyday-life and Working functions such as manipulating with a file, hack saw, hammer, and the like. A possibility is also rendered for the opening of the hand when abducting the thumb, this being due to the two degrees of freedom thereof.

To provide, for an automatic fiexion of the ungual phalanx of the thumb 5 when a clench (or fist) grip occurs, said phalanx is made as a spring-loaded rocker 12 movable at the interphalangeal joint, whereby the grip is made firmer and the appearance of the hand more cosmetical.

To actuate all the motions of the artificial hand, use is made of DC reversible micromotors 13 with a rating of 1.5 w. each. The micromotor 13 of each drive imparts rotation through

gear reducers

14 and 15 to lead screws 16 and 17 which move sliders 18 and 19 of the lever transmission, said sliders being connected to the frame of the four-finger cluster 2 and thumb 5. To reduce noise, the housing of the

reducers

14 and 15 is damped, and the connection of these to the lead screws 16 and 17 is effected through flexible telescopic joint couplings 20 and 21.

The artificial hand of the invention is provided with the mechanism 7 of passive rotation which is essentially a ball bearing whose ball races are made of polyamide resins. When necessary, an automatic spring-actuated locking of the hand is provided.

Due to its small thickness and elasticity the mechanism 7 can be placed over the stump. With the presence .1

of a residual pronating-supinating motility of the stump, said mechanism 7 makes it possible to utilize that motib ity for rotation of the hand.

Low power rating of the drive micromotors allows the hand to be compact and light, resembling in shape that of a natural human hand. At the same time, due to the provision of the independent drive for the first finger 5 and the possibility of self-braking of the drive of the four-finger cluster 2, the force of the grip at the fingertips can amount to 7 kg. which corresponds to a maximum force applied by the fingers of a healthy man when performing most common working and everyday-life functions.

The differential rocker mechanism 3 and both said drives are accommodated inside a common housing which is in effect the body of the palm and Wrist.

As the systems of stepless control of the drives actuating the present multipurpose artificial hand, use is made of an independent bio-electrical control by virtue of signals arriving from the four muscles, as well as a simplified system operated by signals taken off two and three muscles. One of such simplified control systems is that providing for flexure of the thumb 5 and four-finger cluster 2 by way of independent delivery of individual signals from two muscles, whereas extension of all the five fingers is effected when the aforesaid signals are delivered at the same time.

What We claim is:

1. An artificial hand for prostheses with bioelectrical control, comprising: a frame containing a lever-joint unit for the thumb having two directions of movement; a lever-joint system imitating phalanges of the remaining four fingers connected to one another, said system functioning independently of said unit for the thumb; a first drive means for the four-finger lever-joint system, a second drive means for said unit of the thumb, each of said drive means including an independent reversible electric drive unit adapted to be controlled by biological currents from truncated muscles, and flexible links translating motion from said drive units to said lever-joint system of the four fingers and said thumb unit respectively, said thumb unit comprising an individual articulated lever, said lever-joint system of the remaining four fingers including respective levers for each remaining finger, said levers being articulated in pairs, a differential rocker mechanism including two pivotable rocker arms connected to respective pairs of articulated levers and a common control rocker articulated to said rocker arms.

2. An artificial hand as claimed in claim 1 wherein said drive units are independent electric drives including micromotors provided with self-braking screw gears; one of said micromotors being connected to the lever of said thumb while the other micromotor is connected to said common control rocker.

3. An artificial hand as claimed in claim 1 wherein said thumb unit comprises means for an additional passive turning of said thumb unit with respect to an axis perpendicular to the axis of extension thereof, and an automatic spring-actuated locking means for the thumb unit. I

References Cited UNITED STATES PATENTS 2,435,614 2/1948 Tureman 312.7 2,500,614 3/1950 Lohmann 312.7 2,568,299 9/1951 Philpott 3-12.7 2,847,678 8/1958 Opuszenski 312.7

FOREIGN PATENTS 446,809 2/1948 Canada.

509,230 1/1955 Italy.

163,718 1964 U.S.S.R.

RICHARD A. GAUDET, Primary Examiner R. L. FRINKS, Assistant Examiner US. Cl. X.R. 312.7