U.S. patent number 3,751,733 [Application Number 05/228,150] was granted by the patent office on 1973-08-14 for tactile sensing means for prosthetic limbs.
Invention is credited to James C. Administrator of the National Aeronautics and Space Fletcher, N/A, Walter L. Scott.
United States Patent |
3,751,733 |
Fletcher , et al. |
August 14, 1973 |
TACTILE SENSING MEANS FOR PROSTHETIC LIMBS
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,
provided 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
Inventors: |
Fletcher; James C. Administrator of
the National Aeronautics and Space (N/A), N/A (Anaheim,
CA), Scott; Walter L. |
Family
ID: |
22856034 |
Appl.
No.: |
05/228,150 |
Filed: |
February 22, 1972 |
Current U.S.
Class: |
623/24; 623/57;
901/33 |
Current CPC
Class: |
A61F
2/583 (20130101); A61F 2002/5063 (20130101); A61F
2002/5061 (20130101) |
Current International
Class: |
A61F
2/50 (20060101); A61F 2/58 (20060101); A61f
001/00 (); A61f 001/06 (); A61f 001/08 () |
Field of
Search: |
;3/1-1.2,12,2,6 ;340/407
;214/1CM |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
941,312 |
|
Apr 1956 |
|
DT |
|
166,099 |
|
May 1965 |
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SU |
|
249,555 |
|
Jul 1970 |
|
SU |
|
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Frinks; Ronald L.
Claims
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 taction is applied and means fo mounting
the limb on a human appendage comprising:
a temperature transducer and a pressure transducer supported by
said digits for detecting tactile stimuli and providing electrical
output signals proportionate to the magnitude of said stimuli;
a pair of opposed solenoids electrically coupled with said pressure
transducer;
a resistance heater electrically coupled with said temperature
transducer;
strap means for mounting said solenoids and said heater on said
appendage in contiguous engagement therewith with the armatures of
said solenoids 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.
Description
ORIGIN OF THE INVENTION
The invention described herein was made in the performance of work
under a NASA contract and is subject to the provisions of Section
305 of the National Aeronautics and Space Act of 1958, 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
stimulating the sensory organs within the stump of a truncated
appendage.
The prior art is replete with teachings of electromechanical
prosthetic devices having tactile sensors mounted therein and
employed in controlling the operation of the device. Such a device
is shown and described in U.S. Pat. No. 3,509,583 to Anthony V.
Fraioli.
Tactile sensors are employed in such devices for purposes of
controlling the operation thereof. Normally, the sensors are
transducers so connected with selected drive units within the
device that the drive units respond to output signals derived from
the sensors in order to avoid application of excessive pressures to
objects supported within the device.
Currently available prosthetic devices suffer a common deficiency
in that the wearer of the device is insulated from tactile stimuli
to which the device is in normal 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 opportunity 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 tactile 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
tactile 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.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a pictorial view of a prosthetic device including therein
a pressure transducer and a temperature transducer employed in
detecting tactile stimuli.
FIGS. 2 and 3 are pictorial views depicting a slave unit
electrically coupled with the device shown in FIG. 1.
FIG. 4 is a schematic view, in single-line, block diagram form,
depicting circuitry employed in electrically interconnecting the
transducers and the slave unit shown in FIGS. 1 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 part
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, including 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 described embodiment of the instant
invention is included within an artificial hand, the invention can
be embodied 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 electrical 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
pressure 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 intelligence signals indicative of
detected changes in prevailing conditions. Preferably, the
transducer 16 is a piezo diode or tactile sensor which responds to
an application of pressure to provide an electrical output signal
indicative of applied stress. Such a device is referred to in the
aforementioned patent to Fraioli. Similarly, the temperature
transducer 18 responds to temperature changes for providing an
electrical output signal 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 varies
proportionally to changes in the temperature of the resistance.
Hence, due to the innate characteristics of the transducers, the
voltage levels of the intelligence signals derived from the
transducers 16 and 18 increase and decrease proportionally with the
magnitude of the applied stimuli. For example, in the event the
pressure transducer is subjected to increasing stress, the
intelligence signal derived from the transducer 16 is of an
increasing magnitude. Similarly, the inteligence signal derived
from the transducer 18 is increased proportionally with the
increases in the temperatures to which the transducer is
subjected.
The transducers 16 and 18 are coupled electrically with a slave
unit 20, which is activated in response to driver signals received
from a power circuit 22 controlled by the intelligence signals
provided by the transducers 16 and 18. The power circuit 22 is
mounted at any suitable location, including the cuff portion of the
device 10. It should be apparent that the circuit 22 can be
deployed at any suitable location relative to the device 10 so long
as the circuit is interposed electrically between the transducers
16 and 18 and the slave unit 20. Furthermore, it is to be
understood that electrical connections are suitably effected
through a use of electrical lead wires in accordance with currently
acceptable circuit design and fabrication practices
As illustrated, the pressure transducer 16 is coupled with the
power circuit 22 through electrical lead wires 24 extended from the
thumb 12 while the transducer 18 is coupled with the power circuit
22 through suitable lead wires 26 extended from the forefinger 14.
Similarly, the power circuit 22 is coupled with the slave unit 20
through a plurality of lead wires 28 which extend along the surface
of the truncated appendage.
The slave unit 20 preferably includes a pair of electrically
energizable solenoids 30 and a resistance heating element 32
suitably mounted on a strap 34. The strap 34 preferably is a
flexible strap which, when employed, is buckled about the stump of
a truncated appendage for bringing the solenoids 30 and the element
32 into contiguous engagement with the skin of the wearer. In
practice, the solenoids 30 include axially extensible armatures,
not designated, mounted to act in substantial opposition so that
when energized a "pinching" of the flesh of the stump is effected
for thus stimulating the sensory organs located therein.
Consequently, the magnitude of the thus applied pressure is
recognized by the wearer.
Similarly, the resistance heating element 32 is supported in
contact with the skin of the stump so that as the temperature of
the element 32 is elevated, the wearer of the device becomes
cognizant of a change in temperature as the sensory organs in the
stump respond to the changes in temperature occurring in the
element 32.
The power circuit 22 preferably is fabricated employing solid-state
devices and is mounted on a circuit board in a manner consistent
with currently employed circuit design techniques. The power
circuit 22 preferably is energized through a portable D.C. (Direct
Current) power source or battery pack 36, also supported at a
convenient location within the device 10. The power source 36, of
course, also is coupled with the transducers 16 and 18 in a manner
such that an electrical potential is applied thereacross in order
that there is established an electrical condition for the
transducers. This condition is subject to modification, in the
presence of selected tactile stimuli, in a manner consistent with
the function of piezo diodes and the temperature sensitive
resistances, aforediscussed.
To the pressure transducer 16 there is coupled a voltage amplifier
38 coupled within the power circuit 22, while the temperature
transducer 18 is coupled with a voltage amplifier 40. It is to be
understood that the amplifiers 38 and 40 are employed to provide
driver signals at a voltage level substantially above the voltage
level of the intelligence signals derived from the transducers 16
and 18. Accordingly, the amplifiers 38 and 40 include solid state
devices particularly suited for this function.
The output or driver signal derived from the amplifier 38 is fed to
the solenoids 30 while the driver signal derived from the amplifier
40 is fed to the resistance heater 32 through the leads 28. The
driver signal thus delivered from the amplifier 38 simultaneously
is applied across the coils of the solenoid 30 for electrically
energizing the solenoids to extend their armatures simultaneously
to perform a pinching function. Similarly, the signal derived from
the amplifier 40 is applied across an electrical resistance heater
element, not shown, for elevating the temperature of the resistance
heater 32.
It should therefore be apparent that the slave unit 20, in effect,
duplicates the tactile stimuli detected by the transducers 16 and
18 and applies the stimuli directly to the sensory organs within
the stump of the appendage. Due to the fact that the sensitivty of
the sensory organs within the stump may vary, the output derived
from the amplifier circuits 38 and 40 should be a variable voltage
proportionate with the volatage level of the intelligence
signals.
OPERATION
It is believed that in view of the foregoing description, the
operation of the device will be readily under-stood and it will be
briefly reviewed at this point.
With the slave unit 20 fixed to the stump of an appendage, the
prosthetic device 10 is mounted on the stump, in a manner which
forms no part of the instant invention. Further, the device 10 is,
when operated, manipulated in a manner consistent with the design
and operation of prosthetic devices, so that the digits 12 and 14
are caused to engage selected surfaces, such as the surfaces of
objects being grasped. This grasping of objects causes tactile
stimuli to be applied to the surfaces of the digits through
taction. As the hand closes, stress is applied to the pressure
transducer 16 whereby an intelligence signal is delivered from the
transducer to the amplifier 38, whereupon an amplified driversignal
is provided and transmitted to the pair of solenoids 30 of the
slave unit 20. Since the solenoids are located at substantially
opposite sides of the stump, the armatures of the solenoids
simultaneously are extended in opposition to "pinch" the stump
therebetween and thus communicate pressure to the sensory organs
within the appendage. Of course, increasing stress at the
transducer 16 serves to increase the voltage level of the driver
signal derived from the amplifier 38, for thereby increasing the
pinching effect of the solenoids 30. Hence, the pinching effect of
the solenoids is directly proportional to the applied stress at the
pressure transducer 16. Once the stress is removed from the
transducer 16, the solenoids 30 are de-energized and returned to
their inactive position. Thus, the stress applied at the transducer
16 is communicated to the sensory organs within the appendage for
communicating the magnitude of the stress to the wearer of the
device.
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 applied from the power source 36, through
the transducer, is experienced. As the current through the
transducer 18 is increased, the amplifier 40 serves to provide a
driver signal which is then applied to the resistance heater 32. As
the voltage level of the driver signal, applied by the amplifier 40
to the resistance heater 32, is increased, the temperature of the
heater element within the resistance heater is increased and
transmitted 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 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 invention provides a
practical solution to the age-old problem of protecting a wearer by
communicating ambient conditions to which a prosthetic device is
subjected 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 and preferred embodiment, it
is recognized that departures may be made therefrom within the
scope of the invention, which is not to be limited to the
illustrative details disclosed.
* * * * *