WO2000069375A1

WO2000069375A1 - Dexterous prosthetic hand

Info

Publication number: WO2000069375A1
Application number: PCT/US2000/013811
Authority: WO
Inventors: William Craelius; James A. Flint
Original assignee: Rutgers, The State University Of New Jersey
Priority date: 1999-05-19
Filing date: 2000-05-19
Publication date: 2000-11-23
Also published as: WO2000069375A9; AU5146200A

Abstract

A prosthetic device (10) that has independent movement of each digit (12) is provided. The device includes a frame (14) to which a plurality of digits is mounted. A plurality of actuators (32) is also mounted to the frame, and are coupled to the plurality of digits, which cause at least one of the plurality of digits to move independently or concurrently relative to another digit. The actuators of the prosthetic device can be coupled to sensors for sensing a movement and for generating a signal in response to the movement. A controller responsive to the sensor signal generates control signals for input to at least one actuator. The actuator receiving the signal causes at least one of the digits to move, independently, and concurrently with the remaining digits.

Description

DEXTEROUS PROSTHETIC HAND BACKGROUND OF THE INVENTION

1. FIELD OF INVENTION

The present invention relates generally to prosthetic devices. In particular, the present invention provides a prosthetic hand with independent movement of the digits.

2. DESCRIPTION OF RELATED ART

Presently, prosthetics are available that provide for one degree of movement, i.e, gripping or grasping. One example of such a grasping mechanism is discussed in U.S. Patent No. 4,623,354 to Childress et al. The myoelectrically controlled hook opens and closes to grasp and release objects. The device described can be covered with plastic, for aesthetic purposes, to resemble a human hand. Other available devices require that the user wear a shoulder harness to operate the prosthesis.

Although providing a range of motion, none of these devices are known to provide the user with sufficient dexterity in performing ordinary tasks, or provide additional degrees of movement as a natural hand. Accordingly, there is a need for a prosthetic device that offers more than one degree of freedom of movement. There also remains a need for a prosthetic device that provides independent finger dexterity. There also remains a need for a prosthetic device that is power efficient.

SUMMARY OF THE INVENTION

Briefly described, the invention comprises a prosthesis or orthotic device including a frame, a plurality of digits pivotally mounted to the frame, a plurality of actuators mounted on the frame and coupled to the plurality of digits for causing at least one of the plurality of digits to move independently or concurrently relative to another. The prosthesis or orthotic device also includes at least one actuator uniquely coupled to a first corresponding digit of the plurality of digits, and at least one actuators coupled to a second corresponding digit of the plurality of digits for causing the first digit and the second digit to move independently or concurrently relative to another. The invention further includes a controlled prosthesis or orthotic device, including a frame, a plurality of digits pivotally mounted to the frame, a plurality of actuators mounted on said frame and coupled to the plurality of digits, the actuators being coupled to sensors for sensing a desired movement and generating a signal in response thereto, a controller responsive to the sensor signal for generating control signals for input to the at least one actuator, whereby at least one of said actuators receiving one of the signals causes at least one of the plurality of digits to move independently or concurrently relative to another.

These and other features of the invention will be more fully understood by reference to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and aspects of the present invention will be more fully understood in conjunction with the detailed description which follows, and the accompanying drawings, wherein: Figure 1 illustrates the front view of the prosthesis according to the present invention.

Figure 2 illustrates the back view of the prosthesis according to the present invention.

Figure 3 illustrates a side view of the prosthesis according to the present invention. Figure 4 illustrates a schematic diagram of a triply articulating digit. Figure 5a is a palmer side view of the prosthesis holding an object with three digits.

Figure 5b is a back side view of the prosthesis holding an object with three digits.

DETAILED DESCRIPTION OF THE INVENTION During the course of this description, like reference numbers will be used to identify like elements according to the different views that illustrate the invention.

As illustrated in FIG. 1, the prosthetic hand 10 includes a plurality of digits 12a, 12b, 12 c, 12d, and 12e ("12a-e"). Digit 12e is preferably in the form of a thumb. The digits 12a-e, represented as fingers, are pivotally mounted to a frame 14. Digits 12a-d are pivotally mounted to the frame 14 with a cylindrical rod 16 bracketed 18 to the frame 14. The cylindrical rod 16 provides an axis of rotation X for the digits 12a-d. Digit 12e is also pivotally mounted at the base 42 of the digit 12e to the frame 14 and rotates on an axis Y separate from digits 12a-d. Alternatively, the digits 12a-e can be mounted with any suitable means for rotation about axes X and Y on the frame 14.

Each of the digits 12a-e shown has at least a base segment 20 and a top segment 22. The base segment 20 is preferably made of metal, such as aluminum, but may also be composed of a similar rigid and lightweight material such as a polymer, metal alloy, or other suitable composite material, depending upon the needs of the user. The top segment 22 is preferably made of rubber or a polymer that provides non-slip or slightly tacky surface, such as a high molecular weight acetyl homopolymer. Alternatively, the top segment 22 of each of the digits 12a-e is composed of aluminum, polymer, metal alloy, or other suitable composite material, or the entire digit can be composed of a single material, again depending upon the needs of the user. In an alternative preferred embodiment, the digit includes three segments 20, 24 and 26 as shown in FIG. 4.

Each of the digits 12a-e is hinged to provide the capability of performing motion on at least two separate axes as discussed herein. As shown in FIG. 1, there is one hinge 28 on each digit 12a-e that joins the base segment 20 with the top segment 22 of each digit 12a-e. As shown in FIG. 4, two hinges 28 and 30 are provided on the digit to provide capability of motion on three different axes, A, B and X. The hinges 28 and 30 and axes X, Y and A, B, and C correspond to the metacarpal phalangeal and proximal interphlangeal (PIP) joints of a human finger. When coupled to the frame 14, the axis of rotation X and the hinge 28 provide double articulating movement of the digits 12a-d on axes X and A. The thumb 12e has doubly articulating movement on axes Y and C that is provided with the hinge 28 and the pivotal mounting to the frame 14 at the base 42 of the thumb 12e.

The digits 12a-e may be hinged by dowel pins, or other suitable means, to provide the axis of rotation. Each joint or hinge 28 may or may not have a torsion spring, or rubber band 44 to facilitate digit extension as shown in FIG. 2. The coupling of the digits 12a-e to the actuators 32 is discussed below.

The frame 14 is rigid to support digits 12a-e and actuators 32, and is lightweight for portability. The frame 14 has the general shape of a human hand. Preferably the frame 14 is composed of lightweight aluminum. Alternatively, the frame is composed of a metal alloy, titanium, composite, polymer or other suitable material, provided that the frame is rigid, lightweight, and durable, depending upon the needs of the user.

A plurality of actuators 32 are mounted on the palmar portion 34 of the frame 14, and each actuator 32 is coupled to the digits 12a-e by a flexible cable 36. As shown in FIG. 1, each cable 36 is attached to one actuator arm 33 via a releaseable clip 37. The cables 36 are also attached to the distal end 38 of the digits 12a-e by a through-hole 39 and screw 40. In the thumb digit 12e, two actuators 32 are coupled thereto by two separate cables 36. One cable 36 couples the distal end 38 of the digit to the actuator 32, the other cable 36 couples to the base 42 of the thumb 12e. The actuators 32 shown are servo motors that are compactly mounted for the closest spacing possible. All servo motors are mounted in the frame 14 for easy insertion and removal. In a preferred embodiment, the cables 36 are attached to the servo motor lever arms 33 at a point distal to the hinge 28, or hinges 28 and 30 of actuation. Servo motors are currently available from Maxx Products International, Inc. of Zurich, Illinois. Other suitable mounting means may also be used to connect the cables 36 to the digits 12a-e and to the actuators

32.

Each cable 36 couples an actuator 32 to the distal end 38 of each digit 12a-e above the hinge 28 to provide doubly articulating movement of the digit. Alternatively, the cable 36 can be coupled to the digit 12a-e below the hinge 28 to provide singly articulating movement along axis X. The cables 36 provide the appropriate tension, and are formed of braided steel or a monofilament, such as nylon. Nylon is preferred as it provides strength and is lightweight. Other suitable cable materials may also be used.

Six actuators 32 are preferably mounted to the frame in the palmar portion thereof 34 with the use of screws, struts, or other suitable mounting means. At least two actuators 32 are coupled by cables 36 to two digits 12a and 12b in a one- to-one relationship, and at least one actuator 32 is directly coupled to the thumb 12e. This provides movement in three digits 12a, 12b, and 12e as shown in FIGS. 5a and 5b. Alternatively, the thumb can be manually operated or in a fixed position. Any number of digits 12a-e are operable for movement independently and or concurrently as desired by the user. Preferably, four actuators 32 are coupled to four of the digits 12a-d, and two actuators 32 are coupled to the thumb digit 12e via two cables 36 to provide doubly articulating movement at the hinge 28 and the base of the thumb digit 42. Preferably, the actuators 32 are servo motors, as they may be compactly mounted within the frame 14 for optimal use of limited space. Alternatively, other suitable actuator means may be employed in the prosthetic hand 10.

The actuators 32 are typically powered by battery, but a manual override may also be present. The override could enable the user to flex digits by shoulder flexion, transmitted by a harness. This would be accomplished by coupling the harness to the cables 36. The prosthesis 10 operates with a controller such as that described in

"Biomimetic Controller for a Multi-Finger Hand", U.S. Patent Application No. 09/271,673, the disclosure of which is hereby incorporated by reference. In addition, the mathematical methods used in U.S. Patent Application No. 09/494,572, filed January 31, 2000, entitled "Classification of Heart Rate Variability Patterns Using Cepstral Vectors", the disclosure of which is hereby incorporated by reference, may be used by the controller of Serial No. 09/271,673 to identify the intended responses based upon input from a plurality of sensors.

The present prosthesis 10 operates in three modes: tapping, grasping, and proportional control. The mode selection depends on the programming of the microcontroller as set forth in U.S. Patent Application 09/271,673. For example, the default mode programmed by the controller could be tapping, wherein the thumb will be passively extended and the digits are quickly tapped and released a fixed distance in response to a control. In the grasping mode, the digits and /or thumb remain flexed on an object until extended by a volitional release signal as described in U.S. Patent Application Serial No. 09/271,673. The grasping control mode may also be programmed as the default mode. In the proportional mode, the signal is under direct user control, and the digits may be moved a variable distance. The default mode is, of course, programmed according to the needs of the user. The thumb 12e or other digits 12a-d may also be activated directly from the biomimetic sensors. Referring to FIG. 2 , the back view of the prosthetic hand 10 is illustrated.

As shown in FIG. 2, there are a plurality of elastic bands 44 attached to the back of the digit 12a-12e by screws 45. Other means of mounting the bands 44 to the digits 12a-e may be used. Springs or other means may be used to return the digits 12a-e to the original state. After the digits 12a-e are actuated to perform an flexion movement, the elastic bands 44 cause the digits to return to the original state in an extension movement.

Extending from the actuators 32 are connecting wires and connectors 46 that operate with the sensors and the controller as described in U.S. Patent Application Serial No. 09/271,673, incorporated herein. Generally, the sensors are selectively placed to receive muscle and tendon movement in the appropriate portion of the user's natural arm. The actuators are coupled to the sensors for sensing a desired movement and generate a signal in response thereto. A controller, as described in the application incorporated herein, is responsive to the sensor signal and generates control signals for input to at least one actuator. The actuator receiving one of the signals causes at least one of the digits 12a-e to move independently or concurrently relative to another. Referring to FIG. 2, there are a series of adjustable grooves 48 in the base segments 20 of the digits 12a-e that permit adjustment to the tension of the prosthetic hand 10. The tension is adjusted by tightening or loosening the screws 50, according to the needs of the user.

Referring to FIG. 3, there is shown a right side view of a left prosthetic hand 10. The hand 10 is shown with the digits 12a-d slightly curved, which proximates the natural curvature of a human hand. This view shows the hand 10 connected to an artificial limb member 60, which may be mounted on a user. The prosthetic hand 10 at the base is threaded (seen in FIG. 1) to facilitate the mounting of the hand 10 into a socket of such a prosthetic arm 60. The hand 10 may be unscrewed and replaced with other terminal devices. Grooves 48 are also seen in FIGS. 3 and 5b.

Referring to FIG. 4, the structure of the digits includes either singly, doubly, or triply articulating movement at each hinge 28 and 30 and axes X, A and B. The choice of articulating movement depends upon the user, i.e., a user may desire triply articulating movement, and will thus have two hinges 28 and 30, and the appropriate cables 32 connected to a digit or digits 12a-e at a point distal 52 to the hinge 28 and or hinges 28 and 30 of actuation to provide the desired movement. The user may, however, only desire doubly or singly articulating movement, and the cables 32 are connected to the digits 12a-e at the appropriate location to accommodate the user.

Referring to FIGS. 5a and 5b, the prosthetic hand 10 is shown holding a cup 62 with digits 12a, 12b, and 12e. Digits 12c and 12d are shown in phantom in FIG. 5a.

This exemplifies the operation of the prosthetic hand 10 and the independent movement and operation of the digits. Depending upon the needs of the user, any combination of digit movement is available.

The structure resembles the human endoskeleton, both anteriorly and posteriorly, unless covered with a flexible cover, resembling skin and other external features associated with human epidermis. When a protective covering is desired by the user, the structure of the covering is generally in the shape of a glove made of silicon, rubber, or other suitable materials that do not impede hand motion. The protective covering is preferably relatively stiff in the palmar portion, and more flexible in the hinge area, such as an accordion- like configuration, to reduce restraining torque in the movements of the hinges and axes of rotation.

Although the invention has been shown and described in a preferred form with a certain degree of particularity, it is to be understood by those skilled in the art that the present disclosure has been made only by way of example. For instance, although the preferred embodiment depicted herein discloses the use of a cylindrical rod for providing axial movement, other devices, such as a universal joint, are also contemplated, in addition to providing axial movement in the wrist. Further, additional actuators mounted on the back surface of the hand are envisioned, to provide separate control of extension. Numerous such modifications are intended to be included within the scope of the invention as defined in the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A prosthesis or orthotic device, comprising, a frame; a plurality of digits pivotally mounted to said frame; a plurality of actuators mounted on said frame and coupled to said plurality of digits for causing said at least one of said plurality of digits to move independently or concurrently relative to another.

2. The device according to claim 1, wherein said actuators are servo motors.

3. The device according to claim 1, wherein there are five digits, including a thumb member.

4. The device according to claim 1, wherein said digits are provided with at least one hinge.

5. The device according to claim 1, wherein said digits are composed of aluminum and plastic.

6. The device according to claim 1, wherein said plurality of digits are coupled to said actuators via a plurality of cables.

7. A prosthesis or orthotic device, comprising: a frame; a plurality of digits pivotally mounted to said frame; a plurality of actuators mounted on said frame, at least one actuator uniquely coupled to a first corresponding digit of said plurality of digits, and at least one actuator coupled to a second corresponding digit of said plurality of digits for causing said first digit and said second digit to move independently or concurrently relative to another.

8. The device according to claim 7, wherein said actuators are servo motors.

9. The device according to claim 7, wherein there are five digits, including a thumb member.

10. The device according to claim 9, wherein said second corresponding digit is a thumb member.

11. The device according to claim 7, wherein said digits are provided with at least one hinge.

12. The device according to claim 7, wherein said digits are composed of aluminum and plastic.

13. The device according to claim 7, wherein said actuators are coupled to said plurality of digits via cables.

14. A controlled prosthesis or orthotic device, comprising: a frame; a plurality of digits pivotally mounted to said frame; a plurality of actuators mounted on said frame and coupled to said plurality of digits, said actuators coupled to sensors for sensing a desired movement and generating a signal in response thereto; a controller responsive to said sensor signal for generating control signals for input to said at least one actuator; whereby at least one of said actuators receiving one of said signals causes said at least one of said plurality of digits to move independently or concurrently relative to another .

15. The device according to claim 14, wherein said actuators are servo motors.

16. The device according to claim 14, wherein there are five digits, including a thumb member.

17. The device according to claim 14, wherein said digits are provided with at least one hinge.

18. The device according to claim 14, wherein said digits are composed of aluminum and plastic.

19. The device according to claim 14, wherein said plurality of digits are coupled to said actuators via a cable.

20. The device according to claim 16, wherein at least two of said actuators are coupled to said thumb member.