Abstract:
A device designed to assist individuals who have limited use of their hands, the device including a motor-controlled clamp for gripping objects, a microprocessor coupled to the motor-controlled clamp for actuating the motor, an input transducer coupled to the controller to receive input commands from the user to initiate action by the motor-controlled clamp to selectively grip and release an object, and a base for removably attaching the device to the limb of a user, either via straps or to a cast or brace using fasteners.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention pertains to a device and method for augmenting a functional limb and, more particularly, to a mechanism worn on or attached to a user&#39;s arm, wrist, or hand that responds to user commands via an input transducer to activate a motor-controlled clamp for selectively grasping, manipulating, and releasing objects.  
         [0003]     2. Description of the Related Art  
         [0004]     Individuals whose work or hobby calls for long periods of steady hand movement can suffer disabling injuries. Repetitive stress syndrome occurs to anyone—computer operators, photographers, graphics designers, and anyone whose work or hobby calls for long periods of steady hand movement, and repeated grasping, turning, and twisting.  
         [0005]     Injury results when repeated motions case the finger tendons to swell inside a narrow passageway formed by the carpal bones and a tough layer of ligaments. The meridian nerve passes through this tunnel and controls sensation in the fingers, thumb, and some muscles in the hand. Swelling of the tendons causes them to press the nerve against the bone. If the movement patterns that cause the symptoms continue, the hands can eventually lose their ability to firmly grasp objects or even suffer permanent damage.  
         [0006]     Numerous mechanical and electro-mechanical devices have been developed over the years to aid in reducing stress or providing disabled individuals the means for picking up, manipulating, and releasing objects. Although these devices more or less function to meet their objectives, they tend to be cumbersome, clumsy, complicated, and expensive to manufacture and maintain. Examples of such devices are described below.  
         [0007]     A device for controlling and operating paralyzed hands is disclosed in U.S. Pat. No. 2,553,277 wherein multiple springs and cables are connected to the hand, wrist, and finger shields worn by a user. The device is configured so that articles are picked up, gripped, and held between the fingers and the thumb of the user using a mechanical linkage system coupled between the wrist shield and hand and thumb shields that are all eventually coupled to a harness worn over the limb or muscular structure of a user. Thus, this device requires almost marionette-like movement by the user&#39;s body to effectuate movement of the paralyzed hand and fingers.  
         [0008]     A power-assisted upper extremity orthosis is disclosed in U.S. Pat. No. 5,800,561 in which a device controlled by a trigger mechanism operated by one or more fingers of a user operates a pressurized gas supply and electric battery power to operate a mechanical gripping member that is designed to relieve pressure on a users joints suffering from an arthritic condition. This device requires not only an electric motor and power source but also a pneumatic cylinder and gas-operated piston.  
         [0009]     In U.S. Pat. No. 3,631,542, a myoelectric brace consisting of a first wrist-hand splint portion having a movable finger support portion pivotally secured thereto is operated by a hydraulic actuator. The actuator is coupled to a pump that is driven by a battery-powered direct current motor. Three skin electrodes are positioned on the patient&#39;s arm and are configured to sense muscle potentials in the patient&#39;s arm when the patient tenses a muscle in the immediate area of the skin electrodes. The resulting myo-potentials are then amplified by a muscle potential amplifier that transforms the potentials into a varying control signal by a detector circuit and a filter circuit. Relaxation of the patient&#39;s muscle causes the finger support to pivotally move away from the fixed splint portion. This device requires hoses, a fluid chamber, and a fluid-operated actuator in combination with electric circuits in order to operate.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010]     The disclosed embodiments of the invention are directed to a device designed to assist people who either must engage in repeated hand movement or who have limited use of their limbs, and in particular their hands, for providing a mechanism to grasp, pick up, manipulate, utilize, and release objects. An intuitive control switch is coupled with a motor-controlled clamp. In most applications, the motor can comprise a commercially-available servo used by hobbyists for radio-control model aircraft, boats, and cars.  
         [0011]     In one embodiment, the device is capable of opening and closing in a precise motion that is suitable for assisting in everyday tasks and is useful in physical rehabilitation as well as in construction or assembly environments where constant grasping may prove hazardous to worker health.  
         [0012]     In accordance with another embodiment, a device for aiding a user in gripping objects is provided that includes gripping members configured for gripping objects that include at least one movable gripping member, an actuator coupled to the movable gripping member to effectuate movement of the movable gripping member; a controller coupled to the actuator to control actuation of the actuator; an input transducer coupled to the controller and configured to receive input commands to cause the controller to initiate action by the actuator to move the movable gripping member and selectively grip and release an object; and a mounting device for removably mounting the gripping member, actuator, controller, and input transducer to the user.  
         [0013]     In accordance with another aspect of the foregoing embodiment of the invention, the actuator preferably comprises a servo of the radio-controlled model craft type or a DC gear head motor configured to produce from 20 inch-ounces of torque to 600 inch-ounces of torque. The servo is preferably linked with straight linkage between the mounting member and the movable gripping member.  
         [0014]     In accordance with another aspect of the foregoing embodiment, the controller comprises a microcontroller that, when not in use, operates in a sleep mode to conserve power, and when activated by movement of the user&#39;s body, such as pronation or supination of the hand or flexing of the hand about the wrist, initiates activation of the servo. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]      FIG. 1  is a block diagram of one embodiment of a gripping device formed in accordance with the present invention;  
         [0016]      FIG. 2  is an isometric view of a representative implementation of the gripping device of the present invention;  
         [0017]      FIG. 3  is an isometric view of an alternative embodiment of a gripping device formed in accordance with the present invention;  
         [0018]      FIG. 4  is an isometric view of an alternative embodiment of a gripping device formed in accordance with the present invention;  
         [0019]      FIG. 5  is an isometric view of an actuation mechanism of the embodiment of  FIG. 4 ; and  
         [0020]      FIG. 6  is an isometric view of a further embodiment of the gripper device formed in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring initially to  FIG. 1 , shown therein is a block diagram illustrating the basic components of a gripping device  10  formed in accordance with one embodiment of the present invention. The gripping device  10  includes a base member  12  upon which the other components of the gripping device  10  are mounted and which is used for attaching the gripping device  10  to the limb of a user, such as an arm, wrist, or hand, or a combination thereof, or to a foot, leg, or other part of the body.  
         [0022]     Mounted on the base member  12  is a gripping mechanism  14  composed of at least one movable gripping member. Ideally one fixed gripping member is provided, although it is not required. The at least one movable gripping member is pivotally mounted to the base member  12 . Alternatively, two movable gripping members  14  that cooperate to hold and release objects can be pivotally mounted to the base member  12 . Optional attachments for the gripping members  14  can be provided to accommodate different sizes and shapes of objects. Interchangeable gripping members can be used as well.  
         [0023]     The gripping members  14  can comprise multiple gripping members pivotally mounted to the base member  12  to cooperate with a fixed gripping member (not shown) or with each other. Alternatively, flexible gripping members  14  can be used without a hinge to save weight, although such flexible material must be of the type that can handle repeated bending without fatigue or failure.  
         [0024]     The gripping members  14  are coupled to a servo  16  via a linkage  18 . The servo  16  is configured to cause movement of the movable gripping member or members  14  to grasp, manipulate, and release objects. The servo  16  is controlled by a controller  20 , preferably a microcontroller, that is electrically coupled thereto. Both the microprocessor  20  and the servo  16  are energized by a power source  22 , preferably a rechargeable battery, such as a lithium battery. Coupled to an input of the microprocessor  20  is an input transducer  24  that receives commands from a user and in response thereto generates command signals  26  that are received by the microprocessor  20 . The microprocessor  20  in turn generates control signals  28  to the servo  16 .  
         [0025]     In a preferred embodiment, the servo  16  comprises a servo of the type used in radio-controlled model airplanes and cars. Such servos are ideal for this type of application because of their light weight and low power requirements, yet they have sufficient torque to provide the necessary force to grasp objects. Alternatively, a DC gear head motor configured to provide 20 inch-ounces of torque to 600 inch-ounces of torque can be used. While hydraulic or pneumatic actuated servos can be used, such are not preferred because of the required additional hardware that adds weight and complexity.  
         [0026]     In a simple version, the gripping members  14  operate between an opened configuration and a closed configuration in response to a signal from the microprocessor  20  through the servo  16 . In one instance the signal can be a binary on-off signal. However, additional features can be added, including proportional movement in response to the strength of the input signal  26  received from the input transducer  24 , a stepped response to the input signal  26 , or a ratchet-type of response where the gripping members  14  are configured to close in steps and to open in steps. A port on the microprocessor  20  can be included to allow modification of the microprocessor&#39;s reaction to the input signal  26 , such as through software modifications downloaded to a register or memory associated with the microprocessor directly or via wireless transmission.  
         [0027]     The microprocessor  20  is of conventional construction and readily commercially available, and hence it will not be described in detail herein. Preferably, the microcontroller has a sleep mode that, when not actively used, conserves power yet remains available upon receipt of a wake-up signal from the input transducer  24 .  
         [0028]     The input transducer  24  preferably comprises a resistor coupled to the base member in such a way that it changes its resistance in response to movement of the user&#39;s arm, wrist, hand, or a combination thereof. One type of resistor is a bendable resistor that is commercially available. Alternatively, the transducer can comprise other input devices that send a signal, preferably a binary signal, in response to user input. For example, the input transducer  24  can be configured as an eye mouse to detect eye movement. Another form of input is the detection of brainwaves, such as alpha, beta, or theta waves, detected from sensors attached to the user&#39;s head. However, such sensors require additional wiring, and hence this is not a preferred embodiment of the invention. To maintain simplicity and avoiding the use of electrodes attached to the user&#39;s skin, the bendable resistor is an ideal component.  
         [0029]     For general purpose use, the base member  12  is preferably formed of lightweight plastic with bendable resistors associated therewith. The resistor can be embedded within the plastic or mounted thereon. Additional weight can be saved by using plastic gears in the servo  16 . However, for heavy duty applications, such as riding bicycles and scooters, the servo  16  and gripping members  14  can be strengthened through the use of metal gears and components. In addition, the base member  12  can be formed of rigid metal material, wood, composites, plastics, and the like. In this embodiment, the input transducer  24  could be a switch, or other input device that does not require flexing or bending of the base member  12 .  
         [0030]     For heavy duty use, the interchangeable gripping members can be adapted for specialized tasks. For example, a gripping member can be configured to grip the handle of cups, jugs, and the like. Another gripping member can be structured to facilitate grasping of elongate objects, such as knives, forks, and the like.  
         [0031]     Preferably, the base member  12  is configured for mounting on a user&#39;s limb. However, it can also be mounted on a cast or brace worn by the user and affixed in place by a Velcro strap or threaded to studs or other mounting hardware in the cast or brace, or it can be integrally formed with the cast.  
         [0032]     Referring next to  FIG. 2 , shown therein is an isometric view of a hand gripper  30  that includes a plastic base  32  having a bendable resistor  34 , preferably integrally formed therewith. Extending from the base  32  is a pivotally-mounted grip  36  configured to cooperate with a fixed grip  38  also extending from and mounted to the base  32 .  
         [0033]     The movable grip  36  is coupled to a servo  40  via a linkage  42 , which linkage  42  is adjustable to permit adjustment in the starting and ending position of the movable grip  36 . The servo  40  is electrically coupled to a microcontroller  44  that in turn is electrically coupled to the bendable resistor  34  and a power source  46 , in this case a battery. Velcro straps  48  attach the plastic base  32  to the limb of a user.  
         [0034]     In use, the hand gripper  30  functions to augment the user&#39;s fingers and hand in grasping and picking up objects. When the user bends the plastic base  32 , such as by flexing muscles in the wrist or forming a fist, the bendable resistor  34  changes its resistance. The bendable resistor  34  is formed as part of a voltage loop, causing a change in voltage at the microcontroller  44 , which sends a wake-up signal to the microcontroller  44 , which in turn initiates actuation of the servo  40  and causes movement of the movable grip  36 . In one embodiment, the movable grip  36  moves towards the fixed grip  38  until the object is grasped between the movable and fixed grips  36 ,  38 . The movable and fixed grips  36 ,  38  maintain tension on the object until the servo  40  moves the grip  36  in an opposite direction.  
         [0035]     Movement of the grip  36  in a direction away from the object to thereby release the grasp can be initiated by the user relaxing the flexation of the muscles, which in turn changes the resistance of the bendable resistor  34 , thereby altering the voltage received at the input to the microcontroller  44 . In another embodiment, the microcontroller  44  can be configured to operate as a toggle switch in combination with the bendable resistor whereby relaxation of the user&#39;s muscles results in the movable and fixed grips  36 ,  38  maintaining their tension. The tension is released only when the user flexes their muscles a second time, in which case the microcontroller actuates the servo  40  to operate in a reverse direction, causing the movable grip  36  to move away from the fixed grip  38  and release the object.  
         [0036]     As discussed above, the microcontroller  44  can be configured to operate the movable grip  36  in a stepped manner so that it moves a measured distance each time the user causes the resistor  34  to bend. Alternatively, the microcontroller  44  in combination with the servo  40  can operate in a proportional manner, i.e., pivoting the movable grip  36  a distance corresponding to the amount of muscle flexion or corresponding to the length of time the muscle is flexed. Hence, variations in the manner of operation can be programmed into the microcontroller  44 .  
         [0037]     In the embodiment shown in  FIG. 2 , the linkage  42  coupling the servo  16  to the grip  36  is preferably coupled in a straight line to resist backing out due to holding torque. However, the linkage  42  can be adjustable, and a locking mechanism can also be provided to maintain the gripping members  14  in a preferred condition. The adjustable linkage is used to enable positioning of the movable grip  36  at ending and starting positions. In this illustration, the linkage  42  includes a threaded rod  50  received into a rod end  52  for adjustment in the position of the rod end  52  relative to the servo  40 . Rotation of the rod  50  moves the rod end  52  further away from or closer to the servo  40 , which adjusts the movable grip  36  a corresponding distance. It is to be understood that other forms of linkage may be used between the servo  16  and the grip  36  as known to those skilled in the art.  
         [0038]     Referring next to  FIG. 3 , shown therein is another embodiment of the invention wherein a hand gripper  54  is shown attached to a cast  56  by a plurality of fasteners  58 . In this embodiment, like elements from previous embodiments are referred to with identical reference numbers. Here, the base  32  is attached to a cast  56  to provide a more stable platform for heavy-duty applications. Ideally, the base  32  is formed of more rigid material, such as metal. Because the base  32  does not bend, a bendable resistor used in the previous embodiment is not suitable. Instead, a switch  60  is mounted at the proximal end  62  of the base  32  that can be tripped by flexion of the user&#39;s wrist, hand, or finger. Tripping of the switch  60  activates the microcontroller  44  mounted on the servo  40 . It is to be understood that other methods of accepting user input can be used in this embodiment, as previously discussed.  
         [0039]     The movable grip  36  includes a plate  64  mounted at the end thereof to aid in manipulating and holding objects having a more planar configuration. The movable grip  36  and the fixed grip  38  can each be configured to be interchangeable with other each other and with other gripping members that are designed to hold specific tools or handles.  
         [0040]      FIG. 4  is an isometric illustration of another embodiment of the invention in which a gripping device  66  is shown to include a base member  68  that includes a device (not shown) for sensing bending of the base member  68 , a gripping mechanism  70  mounted on the base member  68 , and an actuation system  72  coupled to the sensing device and to the gripping mechanism  70 , the actuation system  72  configured to open and close the gripping mechanism  70  in response to bending of the base member  68 . The device  66  further includes a releasable and adjustable strap  74  for attaching the device  66  to the body of a user, such as to the users arm or wrist or both.  
         [0041]     The gripping mechanism  70  includes a curved fixed grip  76  and a substantially planar movable grip  78  pivotally attached to the fixed grip  76  by a hinge  80 . A helical spring  82  formed as part of the hinge  80  biases the movable grip  78  into contact with the fixed grip  76 . An adjustable link  84  is coupled to the movable grip  78  and to the actuation system  72  such that when the actuation system responds to the sensing device to open the gripping mechanism  70 , the adjustable linkage  84  pulls the movable grip  78  away from contact with the fixed grip  76 . The adjustable linkage  84  may be formed from string, cable, or a flexible filament that is lightweight yet strong enough for this application. Alternatively, a rigid rod that is adjustable in length or nonadjustable, as desired, may be used. The sensing device includes a switch  86 , which is shown in  FIG. 4  positioned on the outside surface of the fixed grip  76 . The switch is configured such that when it is open, the movable grip  78  is urged into contact with the fixed grip  76  by the helical spring  82 . When the switch is closed, the actuation mechanism  72  pulls the fixed grip through the adjustable linkage  84  into an open position by rotating it about the hinge  80  out of contact with the fixed grip  76 .  
         [0042]     The actuation mechanism  76  can be configured to move the movable grip  78  between an open position and a closed position in response to a digital signal, such as a binary signal. Alternatively, the actuation mechanism  72  can be configured to move the movable grip  78  in steps away from the fixed grip  76  and allow it to be urged towards the fixed grip  76  in steps, or to allow it to close immediately from any stepped open position. In accordance with another embodiment, the actuation mechanism  72  can be configured to provide proportional movement of the movable grip  78  in response to proportional bending of the base member  68 . In this embodiment, the bendable resistor described above with respect to  FIG. 1  could be used.  
         [0043]      FIG. 5  is a detailed illustration of the actuation mechanism  72 . As shown therein, the actuation mechanism includes a microprocessor  88  coupled to a power source  90 , in this case a nine-volt battery  90 . The battery  90  is coupled to the microprocessor  88  via a standard snap-on connector  92 . A servo motor  94  is wired to the microprocessor  88  via a first pair of conductors  96 . A second pair of conductors  98  couples the microprocessor  72  to the sensing device (not shown). An actuator arm  98  is coupled to the servo motor  94  and configured for attachment to the adjustable linkage  84  of  FIG. 4 .  
         [0044]     It is to be understood that the actuation mechanism may be formed of integrated circuits, discreet components, or a combination of the same. In addition, lightweight components for the servo motor  94  and the battery  90  may be used to reduce the weight and size of the gripper device.  
         [0045]     In order to provide a more natural feel, an alternative embodiment of the invention shown in  FIG. 6  includes an offset plate  100  that couples the gripping mechanism  102  to the base member  104 . The offset plate  100  positions the gripping mechanism  102  between the thumb  106  and the first finger  108  of the user. It is to be understood that straps or other means for retaining the thumb and finger  106 ,  108  in contact with the gripping mechanism  102  may be used as needed.  
         [0046]     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims and the equivalents thereof.