TECHNICAL FIELD
The present invention relates generally to a prosthetic device for a hand. More specifically, the invention relates to a partial hand prosthesis that substantially replicates the functionality and look of fingers of a human hand. Still more particularly, the invention provides an electro-mechanical fitted and partial hand prosthetic device that senses motion on an area substantially proximate the hypothenar eminence of the remnant portion of a hand in order to activate the motion of a prosthetic finger member moveably attached to a prosthetic harness surrounding the hand.
BACKGROUND OF THE INVENTION
Prior attempts have been made to provide a prosthetic device that simulates the look and functionality of the human hand. Most such attempts fall into two camps: cosmetic type prosthesis and active type prosthesis. Cosmetic type prosthetic devices are generally passive and provide no active functionality. Thus, with a cosmetic limb the patient often resorts to using a working limb to accomplish routine tasks. This is not generally desired as it unnatural and can lead to complications associated with overuse syndrome of the working limb.
An active type prosthesis typically comprises a socket mounted to a patient's arm with a coupling attached to the socket. The coupling provides an attachment point for a terminal device or task specific tools and different tools can be used depending on the particular task to be accomplished. Prosthetic devices of this type are functional but not cosmetically pleasing as they generally don't attempt to mimic the look and feel of a real human hand.
A subclass of the active type class of prosthesis is the electro-mechanical type which tries to replicate both the look and function of the human hand. Such devices typically rely on muscle and tendon forces in other parts of the arm in order to activate the grasping function of the fingers. For example, the upper arm muscle may be flexed in order to cause a set of artificial finger member to come together or grasp an item. However, with such prior art electro-mechanical prosthetic devices, the normal physiologically unconscious use of the device is difficult as the patient may need to concentrate the action of the muscles or tendons providing the operating force.
Partial hand amputations where the thumb remains intact present a common type of limb deficiency. Prior art prosthetic devices adapted to such cases pose significant disadvantages due to overall lack of adjustability during use. In most cases, patients pre-position the device with their working hand to place fingers extending from the device in a position accommodating a proposed task. Even when the prosthetic device is designed with an opposition post, i.e. a member that resists the motion of one or more working digits of the hand, the lack of feedback to the patient requires the patient to reposition the device for each new task.
The cases involving partial hand amputations with thumb intact have not, until the present invention, been treated as a special class of limb loss for purposes of prosthetic treatment. No prior art prosthetic is known to effectively utilize the residual thumb and neighboring structures of the remnant portion of the hand in order to help the patient adjust the grip of the device without use of a functional limb.
BRIEF DESCRIPTIONS OF THE DRAWINGS
The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements, and in which:
FIG. 1 shows a partial hand prosthetic system according to the invention;
FIG. 2 shows is a detailed illustration of a liner which can be used as part of the partial hand prosthetic system of FIG. 1;
FIG. 3 shows the detailed illustration of a prosthetic device which can be used as part of the partial hand prosthetic system of FIG. 1;
FIGS. 4
a-4c illustrate the operation of an opposition member with respect to a remnant thumb;
FIG. 5 illustrates the prosthetic system of the present invention on a remnant portion of a hand;
FIG. 6 is a block diagram illustrating the various electro-mechanical components within a prosthetic device according to the invention;
FIG. 7 shows the details of on exemplary embodiment of a drive subsystem used to move one or more prosthetic fingers of a prosthetic device according to the invention; and
FIG. 8 is a detailed mechanical of one exemplary embodiment of a motor, gear head and drive gear arrangement of a prosthetic device according to the invention.
DETAILED DESCRIPTION
Referring now to the figures, FIG. 1 shows a prosthetic system, denoted generally as 10, consisting of prosthetic device 12 and liner 14 which are designed to fit over a remnant portion 16 of a hand 18. As shown, hand 18 maintains a working thumb thus remnant portion 16 forms a partial hand and prosthetic system 10 is intended to provide a partial hand prosthesis as described herein. In this regard, prosthetic device 12 includes a harness 22 to which one or more prosthetic fingers 24 are movably attached. In a more general sense, prosthetic fingers 24 are designed to move in a direction towards thumb 20 when prosthetic system 10 is worn by a user to a point where it opposes the movement of thumb 20. As such, the terms “prosthetic fingers”, “finger” or “opposition members” can and will be used interchangeably throughout.
Liner 14 provides a means for attaching prosthetic device 12 to remnant portion 16 of hand 18. Preferably, liner 14 provides a snug slip-free fit over remnant portion 16 to securely hold prosthetic device 12 in place (as shown in FIGS. 4a, 4b and 5). In this regard, it has been found that a silicone liner works well although it is contemplated that a suitable liner can be made from other materials all within the scope of the invention. In any event, as shown, liner 14 is shaped to accommodate prosthetic device 12 about opening 26 which is shaped to accept liner 14 as well as remnant portion 16. FIG. 5 shows the entire prosthetic system 10 worn by a user with remnant portion 16 wearing liner 14 and within opening 26 of the prosthetic device 12.
FIG. 2 illustrates further details of liner 14 suitable for use in a prosthetic system according to the invention. Liner 14 provides an opening 30 for inserting the remnant portion 16 of a hand 18 during fitting. Of course, it is contemplated that liner 14 will form a relatively snug fit about a user's hand and that liner 14 including opening 30 and other features thereof may be sized accordingly to accommodate various hand sizes and remnant forms. End periphery 32 of liner 14 is closed forming a glove-like structure for surrounding a remnant portion. In the particular configuration shown, liner 14 includes a second opening 46 for accommodating a thumb. Alternatively, and for cases were a portion of a patient's thumb has been lost, an artificial thumb extender 44 can be attached to the liner 14 to extend opening 46 into a structure substantially approximating a human thumb. Liner also includes areas 40 and 42 which are near an area known as the hypothenar eminence near the lateral portion of a human hand. Finally, liner 14 provides an attachment point 48 to which the prosthetic device 12 can be secured. The invention is not limited to any specific means of attaching the prosthetic device 12 to the liner 14 although it is preferred that prosthetic device 12 be securely attached to the liner 14.
FIG. 3 shows the prosthetic device 12 in more detail. Harness 22 provides a structure to which the various electro-mechanical components for a prosthesis according to the invention can be attached. Opposition members 24 are moveably attached to frame 50 which can rotate about shaft member 52 in the direction of arrow A. Shaft member 52 is provided to allow the rotational motion of the opposition members 24 about harness 22. As shown, attached to harness 22 are sensors 60 and 62 which are positioned about an area where the hypothenar eminence of a remnant portion of a hand inserted into opening 26 of harness 22 would be. Each sensor is communicably attached to a controller, represented by 70, which receives signals from the sensors 60, 62 corresponding to motion of the remnant portion within harness 22. The controller 70 is shown attached to the outside of harness 22 although the controller 70 can likewise be placed in other areas about the harness 22 consistent with the invention. Another block 72 is shown attached to harness 22 and is representative of a power source, such as rechargeable batteries, used to provide energy to the various electro-mechanical components of the prosthetic device 12. This would include controller 70 and motor (not shown in FIG. 3) to drive the shaft member 52 and cause opposition members 24 to pivot about harness in the direction of arrow A.
FIGS. 4
a, 4b and 4c illustrate the operation of a prosthetic system, such as prosthetic system 10, according to the invention. In particular, the lateral edge 80 of a remnant portion 16 of a hand 18 is shown. As shown, remnant portion 16 includes a remnant thumb 82 which is functioning normally. In FIG. 4b, the prosthetic device has been fitted over liner 14 which, in turn, has been fit over remnant portion 16. A shaft member 52 is mechanically coupled to the opposition member 24 and operated by a motor (not shown in FIG. 4b). As shown, sensors 60 and 62 are arranged proximate to area 80 which is in the vicinity of the hypothenar eminence of the remnant portion 16. In this position, the sensor 60, 62 are situated to detect the motion of the hypothenar eminence which causes the movement of opposition member 24. The fact that motion of the hypothenar eminence causes motion of opposition members 24 provides a prosthetic device that is physiologically natural for a patient using a prosthetic system according to the invention.
FIG. 4C shows the opposition member 24 moving in the direction of remnant thumb 82 after motion has been activated. This motion more naturally mimics the function of a human finger opposing the thumb during normal use. Thus, the invention provides a prosthetic system that is both functional and cosmetically similar to a human hand.
FIG. 5 shows an alternate view of a prosthetic system according to the invention. Harness 22 of prosthetic device 12 is slipped over liner 14 and held securely in place by strap 110 looping through opening 112 and holding with attachment point 48. Of course, other ways of holding prosthetic device 12 in place may be utilized. Sensor 60 is communicably coupled via signal line 120 to a controller (not shown in FIG. 5) that actuates motor 100 to drive shaft 102 and thereby operate shaft member 52 coupled to opposition members 24. In this way, motion detected by sensor 60 causes the movement of opposition members 24.
It is contemplated that a variety of electro-mechanical components and device designs may be employed in order to achieve a prosthesis embodying a prosthetic device and system according to the present invention. Therefore, presented herein is but a single embodiment of various electro-mechanical devices and components which have been found to provide the objects and advantages of the invention. As such, FIG. 6 is a block diagram for a prosthetic device, denoted generally as 140, including the various electro-mechanical devices and components according to a general embodiment of the invention. A microprocessor 150 acts as the central processing unit of the prosthetic device 140 and receives an input from touch pads 152 via signal path 151. Touch pads 152 are positioned within a prosthesis structure, such as harness 22, where movements of the hypothenar eminence can be detected and communicated to microprocessor 150. As shown, power is derived from a set of rechargeable batteries 160 which, in combination with charger port and power switch 162 as well as battery charger 164, are capable of providing energy to various electro-mechanical components of the prosthetic device 140.
Prosthetic device 140 also includes a DC motor 170 operably coupled to microprocessor 150 via path 171. Thus, microprocessor 150 may actuate DC motor 170 following the receipt of a detect signal from touch pads 152. DC motor 170 may, in turn, operate gear head 172 to cause the motion of finger member 174. As shown, DC motor 170, gear head 172 and finger 174 are supported by bracket 176.
Referring to FIG. 7, a block diagram for a prosthetic device according to the invention with the details of a drive system, denoted generally as 200, is shown. Specifically, controller 70 is communicably coupled to touch pads 152a and 152b. In addition, controller 70 is provided with port 202 to receive programming instructions from computer 210 via signal path 212. In this way, the controller 70 can be programmed to configure various features of the prosthetic device. For example, computer 210 can be used to set the sensitivity of the touch pads 152a, 152b. In addition, computer 210 can be used to set the direction and speed of the DC motor 170 in order to effect the action of fingers 174. Also, the limit for the stall current of the DC motor 170 can be set. Of course, other variable and features of the prosthetic device can be changed, modified or set using computer 210 though port 202.
As shown, DC motor 170 is in operative communication with planetary gear head 220 which receives a first torque force from the output 219 of DC motor 170 and converts it to a second torque force suitable for driving driven shaft 226 and providing sufficient torque to move fingers 174. This may be accomplished by setting the gear ratio between the input and output of the planetary gear 220 in order to provide a sufficient torque of the driven shaft 226. While various gear ratios can be used, it has been found that a high ratio with respect to the input and out is satisfactory. In particular, according to one specific embodiment, a gear ratio of 1024:1 has been found to provide a sufficient torque force at the driven shaft 226 while preventing back drive of the motor 170. Of course, other ratios may be employed within the scope of the present invention.
The planetary gear head 220 is operably coupled to gear spurs 222 and 224 which transfer the torque generated by DC motor 170 and gear head 220 to the driven shaft 226 coupled to fingers 174. Other transfer methods may also be employed including, for example, a three gear spur arrangement as shown in FIG. 8. In this way, power provided by the DC motor 170 can be used to move fingers 174. Of course, it is contemplated that variations of the drive subsystem 200 will be apparent to those of ordinary skill in the art and, therefore, such variations should be considered within the scope of the invention.
A mechanical layout of a drive system suitable for use in a prosthetic device according to the invention is shown in more detail in FIG. 8. The drive system, denoted generally as 250, uses a motor 252 to operate gear head 254 along shaft 256. Frame 260 supports these various components as gears 270 transfer mechanical power from the motor 252 to finger members 274 attached to rod 272. A power connector 280 supplies energy from a power source (not shown in FIG. 8) to the motor 252.
As indicated above, various devices and components can be used in order to achieve a prosthetic device having the various features and advantages of the present invention. Table 1 below provides some a material list for some of the electrical and mechanical devices which have been found satisfactory in reducing to practice a suitable prosthesis according to the invention:
TABLE 1
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List of parts and part numbers for devices and
components used in an exemplary prosthetic
device according to the invention.
Part NumPart NameQuantityVendor
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118396Motor, 6 V DC1.0Maxon
218418Gearhead, Planetary Type,1.0Maxon
1024:1
UPB563450/PCMBattery, 3.7 Volt, Lithium2.0Ultralife
Ion
B84-0500/0550Battery Charger, Lithium1.0Energy
Ion, 1000 mAAccess
910-2050-05Index Finger2.0MIL-E
970-2060-01 REV CHand Mounting Assembly1.0MIL-E
970-2060-10 REV BGear Cover1.0MIL-E
970-2060-20Motor Shaft1.0MIL-E
970-2060-30Bearing2.0MIL-E
970-2060-05 REV CAxle1.0MIL-E
KJ08412KTie Wrap1.0Dennison
FIT-221B, 3/32Heat Shrink, Black1.0Alpha
16P-3100Charging Jack1.0Mouser
910-2020-01Power Shutoff Plug,1.0MIL-E
Modified
N/AMounting Screws,4.0Global
#4-40 × .125, PFH, SS
N/APlateScrews,4.0Global
#6-32- × .125, PPH, SS
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It should be understood that modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
Patent Application
20060212129
