An improved prosthetic device characterized by a frame and a socket for mounting on the stump of a truncated human appendage is described. Flexible digits extend from the distal end and transducers located within the digits act as sensing devices for detecting tactile stimuli. The transducers are connected through a power circuit with a slave unit supported by a strap and fixed to the stump. The tactile stimuli detected at the sensing devices are reproduced and applied to the skin of the appendage in order to stimulate the sensory organs located therein

Scott, W. L.

English

NASA Technical Reports Server

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON, DC 20546
REPLY TO _
ATTN OF GP OCT 1 5 1973
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KS I/Scientific & Technical Information Division
Attention: Miss Winnie M. Morgan
FROM: GP/Office of Assistant General Counsel for
Patent Matters
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In accordance with the procedures agreed upon by Code GP
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U.S. Patent No. ; J, / J11 I 3->
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NASA Patent Case No.
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NOTE - If this patent covers an invention made by a corporate
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the Specification, following the words "... with respect to
an invention of . . ." f^fizlBj?)
'''<&
Elizabeth A. Carter
Enclosure
Copy of patent cited above
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https://ntrs.nasa.gov/search.jsp?R=19730023281 2020-03-17T09:11:53+00:00Z
United States Patent
Fletcher et al.
[in 3,751,733
[45] Aug. 14, 1973
[ 54 ] TACTILE SENSING MEANS FOR
PROSTHETIC LIMBS
[76] Inventors James C. Fletcher, Administrator of
the National Aeronautics and Space
Administration with respect to an
invention of, Walter L. Scott,
Anaheim, Calif.
[22] Filed Feb. 22, 1972
[21] Appl No 228,150
[52] U.S. Cl. . 3/1.1,3/2,3/6,
3/12
[51] Int. Cl. A61f 1/00, A61f 1/06, A61f 1/08
[58] Field of Search . . .. 3/1-12,
3/12, 2, 6, 340/407, 214/1 CM
[56] References Cited
UNITED STATES PATENTS
2,582.234 1/1952
3,535.711 10/1970
3,575,158 4/1971
2.567,066 9/1951
Conzelman, Jr et al
Pick
Summers
Goldman
3/1 2 X
3/1 2
3/1
3/1 1
FOREIGN PATENTS OR APPLICATIONS
941,312 4/1956 Germany ... 3/1 1
166,099 5/1965 U S S R 3 / 1 1
249,555 7/1970 U S S R . 3 / 1 1
Primary Examiner—Richard A Gaudet
Assistant Examiner—Ronald L. Fnnks
Attorney-L D Wofford.Jr and John R Manning
[57] ABSTRACT
An improved prosthetic device characterized by a
frame including a socket for mounting the frame on the
stump of a truncated human appendage and having a
plurality of flexible digits extended from the distal end
thereof. Within the digits there are transducers, pro-
vided as sensing device for detecting tactile stimuli,
connected through a power circuit with a slave unit
supported by a strap and fixed to the stump, whereby
the tactile stimuli detected at the sensing devices are
reproduced and applied to the skin of the appendage
for thus stimulating sensory organs located therein
1 Claim, 4 Drawing Figures
I-1'
\
PATENTED AUGMB73 3,751,733
TEMPERATURE
TRANSDUCER
NORMALLY
OPEN
PRESSURE
SENSORS
V6
3,751,733
TACTILE SENSING MEANS FOR PROSTHETIC
LIMBS
ORIGIN OF THE INVENTION
The invention described herein was made in the per-
formance of work under a NASA contract and is sub-
ject to the provisions of Section 305 of the National
Aeronautics and Space Act of 19S8, Public Law
85-568 (72 Stat, 435, 42 U S.C 2457)
BACKGROUND OF THE INVENTION
The invention relates generally to prosthetics and
more particularly to an improved prosthetic device
having sensing means supported within the digits
thereof for detecting tactile stimuli, and a slave unit
driven in response to the detected stimuli for stimulat-
ing the sensory organs within the stump of a truncated
appendage
The prior art is replete with teachings of electrome-
chanical prosthetic devices having tactile sensors
mounted therein and employed in controlling the oper-
ation of the device Such a device is shown and de-
scribed in U S Pat No 3,509,583 to Anthony V Frai-
oli.
Tactile sensors are employed in such devices for pur-
poses of controlling the operation thereof Normally,
the sensors are transducers so connected with selected
drive units within the device that the drive units re-
spond to output signals derived from the sensors in
order to avoid application of excessive pressures to ob-
jects supported within the device
Currently available prosthetic devices suffer a com-
mon deficiency in that the wearer of the device is insu-
lated from tactile stimuli to which the device is in nor-
mal usage subjected Consequently, a wearer cannot
detect stress and heat or the magnitude of the stress or
heat applied to the device through touch or taction
Hence, there currently exists a need for an improved
prosthetic device which affords the wearer an opportu-
nity to "feel" pressure, heat and similar tactile stimuli
to which the device is subjected through taction.
SUMMARY OF THE INVENTION
It is therefore an object of the instant invention to
provide an improved prosthetic device
It is another object to provide an improved prosthetic
device having sensing units supported by the digits and
coupled with slave units responsive to the sensing units
for stimulating the sensory organs within the stump of
a truncated appendage.
It is another object to provide an improved prosthetic
device through which tactile stimuli are applied to the
wearer in response to an application of tactile stimuli
to the device.
It is another object to provide in a prosthetic device
a plurality of transducers for electrically detecting tac-
tile stimuli and for applying to sensory organs within'a
truncated appendage tactile stimuli simulating detected
stimuli
These and other objects and advantages are achieved
through an improved prosthetic device consisting of a
frame including therein a socket for mounting the
frame on a human appendage and a plurality of digits
extended from the distal end of the frame, a plurality
of transducers supported in the digits, for detecting tac-
tile stimuli, and a slave unit configured to be strapped
to the stump of a truncated appendage and connected
with the sensing units so that tactile stimuli detected by
the sensing units are communicated to sensory organs
of the stump, through the slave unit
5 BRIEF DESCRIPTION OF THE DRAWING
FIG 1 is a pictorial view of a prosthetic device in-
cluding therein a pressure transducer and a tempera-
ture transducer employed in detecting tactile stimuli
FIGS 2 and 3 are pictorial views depicting a slave
10 unit electrically coupled with the device shown in FIG
1.
FIG 4 is a schematic view, in single-line, block dia-
gram form, depicting circuitry employed in electrically
interconnecting the transducers and the slave unit
IS shown in FIGS I through 3.
DESCRIPTION OF THE PREFERRED
EMBODIMENT
Referring now to the drawing wherein like reference
characters designate like or corresponding parts
throughout the several views, there is shown in FIG 1
an improved prosthetic device 10 which embodies the
principles of the instant invention.
As illustrated, the device 10 is an electro-mechanical
hand of any suitable design Since prosthetic devices,
such as electro-mechanical hands, are well known and
form no specific pan of the instant invention, a detailed
description of the device 10 is omitted in the interest
of brevity Suffice it to understand that the device 10
includes suitable mechanical drive units, not shown, in-
cluding motors and the like for driving extended digits
of the device in a cyclic operation Furthermore, it is
to be understood that the device 10 may, if so desired,
assume the configuration of a foot rather than a hand.
Accordingly, it should be apparent that while the de-
sen bed embodiment of the instant invention is included
within an artificial hand, the invention can be embod-
ied in prosthetic devices of other appendages equally as
well
The digits of the device 10, designated 12 and 14,
support, near their distal ends, suitable sensing units
which respond to applied tactile stimuli to provide elec-
trical output signals of a magnitude proportionate to th
magnitude of the stimuli. As illustrated, within the digit
12, which represents the thumb, there is seated a pres-
sure transducer 16, while within the digit 14, which
represents a finger, there is a temperature transducer
18. It is to be understood that the transducers 16 and
18 are of any suitable design capable of providing intel-
ligence signals indicative of detected changes in pre-
vailing conditions. Preferably, the transducer 16 is a
piezo diode or tactile sensor which responds to an ap-
plication of pressure to provide an electrical output sig-
nal indicative of applied stress. Such a device is re-
ferred to in the aforementioned patent to Fraioli. Simi-
larly, the temperature transducer 18 responds to tem-
perature changes for providing an electrical output sig-
nal at a voltage level dictated by the temperature of the
transducer Preferably, the temperature transducer 18
is a variable resistance unit having thermally variable
conductivity characteristics for providing electrical
output signals, the magnitude of the amperage of which
vanes proportionally to changes in the temperature of
the resistance
Hence, due to the innate characteristics of the trans-
ducers, the voltage levels of the intelligence signals de-
rived from the transducers 16 and 18 increase and de-
20
25
30
35
40
45
50
55
60
65
3,751,733
3 4
crease proportionally with the magnitude of the applied To the pressure transducer 16 there is coupled a volt-
stimuli For example, in the event the pressure trans- age amplifier 38 coupled within the power circuit 22,
ducer is subjected to increasing stress, the intelligence while the temperature transducer 18 is coupled with a
signal derived from the transducer 16 is of an increas- voltage amplifier 40. It is to be understood that the am-
mg magnitude Similarly, the mteligence signal derived 5 plifiers 38 and 40 are employed to provide driver sig-
from the transducer 18 is increased proportionally with nals at a voltage level substantially above the voltage
the increases in the temperatures to which the trans- level of the intelligence signals derived from the trans-
ducer is subjected ducers 16 and 18. Accordingly, the amplifiers 38 and
The transducers 16 and 18 are coupled electrically 40 include solid state devices particularly suited for this
with a slave unit 20, which is activated in response to 10 function.
driver signals received from a power circuit 22 con- The output or driver signal derived from the ampli-
trolled by the intelligence signals provided by the trans- fier 38 is fed to the solenoids 30 while the driver signal
ducers 16 and 18. The power circuit 22 is mounted at derived from the amplifier 40 is fed to the resistance
any suitable location, including the cuff portion of the heater 32 through the leads 28. The driver signal thus
device 10. h should be apparent that the circuit 22 can l5 delivered from the amplifier 38 simultaneously is ap-
be deployed at any suitable location relative to the de- Plled across the colls of the solenoid 30 for electrically
vice 10 so long as the circuit is interposed electrically energizing the solenoids to extend their armatures si-
between the transducers 16 and 18 and the slave unit multaneously to perform a pinching function Similarly,
20. Furthermore, it is to be understood that electrical the Sl8nal derlved from the amplifier 40 is applied
connections are suitably effected through a use of elec- 20 across an electrical resistance heater element, not
tncal lead wires in accordance with currently accept- shown- for elevating the temperature of the resistance
able circuit design and fabrication practices heater 32.
As illustrated, the pressure transducer 16 is coupled ll should therefore be apparent that the slave unit 20,
with the power circuit 22 through electrical lead wires ,. in effect- duPllcates the tactile stimuli detected by the
24 extended from the thumb 12 while the transducer 2S transducers 16 and 18 and .ppl.es the stimuli direct^
18 is coupled with the power circuit 22 through suit- to the sensory organs within the stump of the append-
able lead wires 26 extended from the forefinger 14. *& Due <° the, fact that the ^^^ °f the f501*
c- i i .L ..,-, i j .u . i T i organs within the stump may vary, the output derivedSimilarly, the power circuit 22 is coupled with the slave , 6 , . _ ,i J, „«
 L ij ._
. in .u u i i .
 c i j 10 i. u from the amplifier circuits 38 and 40 should be a van-unit 20 through a plurality of lead wires 28 which ex- ,n . , . v . . ... . . , , ,j • .. _5 - . j j a°le voltage proportionate with the volatage level oftend along the surface of the truncated appendage. •. n iTU i •»/» r LI i j r i » the intelligence signalsThe slave unit 20 preferably includes a pair of electn- " B
cally energizable solenoids 30 and a resistance heating OPERATION
element 32 suitably mounted on a strap 34. The strap
 ft n ^^ ^ jn vfew of the f de .
34 preferably ,s a flexible strap which, when employed, 35
 tlon the Operat,on of the device will be readily under-
is buckled about the stump of a truncated appendage
 stood and ,{ wl,, be bnefl reyiewed Rt ^  'fflt
for bringing the solenoids 30 and the element 32 mto
 W)th ^  s)ave umt 2Q fixed tQ ^ s Q{ ^
contiguous engagement with the skm of the wearer In
 pendagei the prosthetic device 10 is mounted on the
pract.ce, the solenoids 30 include axially extensible ar-
 g m a manner wh,ch fofms n<> of ^ mgtant
matures, not designated, mounted to act in substantial 40
 mventlon Further) the device 10 is, when operated,
opposition so that when energized a "pinching" of the
 manipu,ated ln a manner consistent with the design and
flesh of the stump is effected for thus stimulating the operation of prosthetic devices, so that the digits 12
sensory organs located therein. Consequently, the mag-
 and 14 are caused to engage selected surfaces, such as
mtude of the thus applied pressure is recognized by the
 the surfaces Of objects being grasped This grasping of
wearer
 objects causes tactile stimuli to be applied to the sur-
Similarly, the resistance heating element 32 is sup-
 faces of the digits through taction As the hand closes,
ported in contact with the skin of the stump so that as
 stress ls appi,ed to the pressure transducer 16 whereby
the temperature of the element 32 is elevated, the
 an intelligence signal is delivered from the transducer
wearer of the device becomes cognizant of a change in
 to the amplifier 38, whereupon an amplified dnversig-
temperature as the sensory organs in the stump respond 50
 na, K provlded and transmitted to foe pair of solenoids
to the changes in temperature occurring in the element 30 of the slave unit 20. Since the solenoids are located
32. at substantially opposite sides of the stump, the arma-
The power circuit 22 preferably is fabricated employ- tures of the solenoids simultaneously are extended in
ing solid-state devices and is mounted on a circuit opposition to "pinch" the stump therebetween and
board in a manner consistent with currently employed 55 thus communicate pressure to the sensory organs
circuit design techniques The power circuit 22 prefer- within the appendage. Of course, increasing stress at
ably is energized through a portable D C (Direct Cur- the transducer 16 serves to increase the voltage level of
rent) power source or battery pack 36, also supported the driver signal derived from the amplifier 38, for
at a convenient location within the device 10. The thereby increasing the pinching effect of the solenoids
power source 36, of course, also is coupled with the 30. Hence, the pinching effect of the solenoids is di-
transducers 16 and 18 in a manner such that an electn- rectly proportional to the applied stress at the pressure
cal potential is applied thereacross in order that there transducer 16. Once the stress is removed from the
is established an electrical condition for the transduc- transducer 16, the solenoids 30 are de-energized and
ers This condition is subject to modification, in the ,, returned to their inactive position Thus, the stress ap-
presence of selected tactile stimuli, in a manner consis- plied at the transducer 16 is communicated to the sen-
tent with the function of piezo diodes and the tempera- sory organs within the appendage for communicating
ture sensitive resistances, aforediscussed. the magnitude of the stress to the wearer of the device.
3,751,733
Where the transducer 18 located in the forefinger of
the device 10 encounters an elevated temperature, an
increase in the conductivity of the electrical current ap-
plied from the power source 36, through the trans-
ducer, is experienced As the current through the trans- 5
ducer 18 is increased, the amplifier 40 serves to pro-
vide a driver signal which is then applied to the resis-
tance heater 32. As the voltage level of the driver sig-
nal, applied by the amplifier 40 to the resistance heater
32, is increased, the temperature of the heater element 10
within the resistance heater is increased and transmit-
ted to the sensory organs within the skin of the wearer
of the device Thus an increased temperature at the
transducer 18 is communicated to the sensory organs
of the appendage through the resistance heater 32 so is
that the increased temperature is communicated to the
wearer of the device
In view of the foregoing, it should readily be apparent
that the improved prosthetic device of the instant in-
vention provides a practical solution to the age-old 20
problem of protecting a wearer by communicating am-
bient conditions to which a prosthetic device is sub-
jected to the sensory organs of the wearer
Although the invention has been herein shown and
described in what is conceived to be the most practical 25
and preferred embodiment, it is recognized that depar-
tures may be made therefrom within the scope of the
invention, which is not to be limited to the illustrative
30
35
40
45
50
55
60
details disclosed
I claim
1. Tactile Sensing Means for a prosthetic limb of the
type including a terminal member having a plurality of
digits extending therefrom through which faction is ap-
plied and means fo mounting the limb on a human ap-
pendage comprising
a temperature transducer and a pressure transducer
supported by said digits for detecting tactile stimuli
and providing electrical output signals proportion-
ate to the magnitude of said stimuli,
a pair of opposed solenoids electrically coupled with
said pressure transducer,
a resistance heater electrically coupled with said tem-
perature transducer,
strap means for mounting said solenoids and said
heater on said appendage in contiguous engage-
ment therewith with the armatures of said sole-
noids disposed on opposite sides of said appendage
whereby as taction is applied to said digits, tactile
stimuli are detected by said sensing means and
communicated to said appendage proportionate to
the magnitude of said stimuli, with said armatures
when energized applying pressure to the flesh of
said appendage and said heater applying heat to
said appendage
65


Tactile sensing means for prosthetic limbs

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