Abstract:
A gripping device that comprises a first moveable jaw and a second fixed jaw is disclosed. The gripping device has a handle operatively engaged to the first moveable jaw and a connecting link operatively engaged to the first moveable jaw. The connecting link is positioned in at least one of a first position or a second position. The change in the position of the connecting link allows the gripping device to have either a default closed position or a default open position, which can be defined by voluntarily-open or voluntary-close modes of operation, respectively. The first moveable jaw moves in either of the modes of operation. The change in the mode of operation is accomplished through use of a connecting link that is passed through a singularity during the switching process to achieve the different output positions and directions.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional that claims benefit to U.S. Provisional Patent Application No. 61/702,642 filed on Sep. 18, 2012, which is herein incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    The present document relates generally to prosthetics and in particular, to a gripping device for a prosthesis having switchable open and close modes of operation. 
       BACKGROUND 
       [0003]    An estimated 41,000 people in the United States live with an upper limb loss at or above the wrist. The loss of a limb by an individual can profoundly limit everyday activities such as dressing, eating, and performing personal hygiene tasks. The loss of a limb may also affect social interactions and personal relationships and in some cases can threaten the basic independence of the individual. Further, the individual can experience difficulty in grasping and holding objects which may impede leisure activities, such as reading or playing sports. The inability to properly operate a prosthetic by the individual may also prevent performance of certain employment tasks or severely limit future job prospects, thereby impacting a person&#39;s financial security, sense of identity and purpose, and overall quality of life. 
         [0004]    Conventional passive prosthetic devices may be very lightweight and relatively inexpensive to manufacture; however, such prosthetic devices provide very limited function. Body-powered devices are generally light, robust, functional, and inexpensive. The majority of these devices have a voluntary-open (VO) mode of operation, while several others have a voluntary-closing (VC) mode of operation. A few devices have both a VO and a VC mode of operation. However, these devices are complex and require altering the initial positions of the jaws and the direction of movement, without altering the direction of movement and starting position of a Bowden cable attachment. As such, there remains a need for a gripping device or similar prosthetic device that can quickly and easily switch between voluntary-open and voluntary modes of operation without extensive adjustments. 
       SUMMARY 
       [0005]    In one embodiment, a gripping device may include a first movable jaw and a second fixed jaw. The gripping device includes a handle operatively engaged to the first movable jaw. A connecting link is operatively engaged to the first moveable jaw. The connecting link is positioned in at least one of a first position or a second position. In the first position, the connecting link causes the first moveable jaw to move inwardly relative to the second fixed jaw when the handle is moved inwardly, while in the second position the connecting link causes the first moveable jaw to move outwardly relative to the second fixed jaw when the handle is moved inwardly. In either position, an equilibrium position of the handle remains the same when the connecting link is in the first position or in second position. 
         [0006]    In another embodiment, a gripping device may include a first moveable jaw and a second fixed jaw. The gripping device also includes a handle operatively engaged to the first moveable jaw. In addition, a connecting mechanism is operatively engaged to the first moveable jaw. The connecting mechanism is positioned in at least one of a first position or a second position. In the first position, the connecting mechanism causes the first moveable jaw to move inwardly relative to the second fixed jaw when the handle is moved inwardly, while in the second position the connecting mechanism causes the first moveable jaw to move outwardly relative to the second fixed jaw when the handle is moved inwardly. The connecting mechanism causes the alternating movements of the first moveable jaw by imparting a force on the first moveable jaw through a singularity. As used herein, a singularity refers to point along a mechanical linkage wherein the motion of the jaw on one side of the singularity is different in response to the same motion of the handle on the other side of the singularity. 
         [0007]    In another embodiment, the mechanism includes one or more hydraulic channels operatively engaged to the first moveable jaw for causing the first moveable jaw to open relative to the second fixed jaw when the handle is moved inwardly or alternately causing the first moveable jaw to close relative to the second fixed jaw when the handle is moved inwardly. The alternating movement of the first moveable jaw is accomplished by directing the flow of fluid through alternating hydraulic channels on either side of a singularity, causing a reversal in movement about the pivot. 
         [0008]    In another embodiment, a cable is used as the mechanism that is operatively engaged to the first movable jaw for alternately causing the first moveable jaw to move inwardly or outwardly relative to the second fixed jaw when the handle is moved inwardly. The alternating movement of the first moveable jaw is accomplished by passing a cable through a singularity. 
         [0009]    Additional objects, advantages, and novel features of the invention shall be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and the advantages may be realized and attained by means of the instrumentalities and in combinations particularly pointed out in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is an exploded view of a gripping device according to one embodiment. 
           [0011]      FIG. 2  is a plan view of the gripping device according to one embodiment. 
           [0012]      FIG. 3  is a side plan view of the gripping device according to one embodiment. 
           [0013]      FIG. 4  illustrates an embodiment of the gripping device in a voluntary-open mode of operation and a voluntary-close mode of operation. 
           [0014]      FIGS. 5-7  depict the motion of linkages through a singularity. 
           [0015]      FIG. 8  depicts the gripping device in the voluntary-open mode of operation. 
           [0016]      FIG. 9  depicts the gripping device in a voluntary-close mode of operation. 
       
    
    
       [0017]    Corresponding reference characters indicate corresponding elements among the view of the drawings. The headings used in the figures should not be interpreted to limit the scope of the claims. 
       DETAILED DESCRIPTION 
       [0018]    As described herein, the gripping device of the present disclosure is a device that may be switched between a voluntary-open (VO) mode of operation and a voluntary-close (VC) mode of operation. When in the VO mode of operation, a user actuates one or more handles of the gripping device to open the jaws of the device. When released, the handles of the device return to a default position, which in turn causes the jaws of the gripping device to return to a default position so that jaws can be used to grasp an object using the force provided by a biasing component, such as a spring or elastic band. 
         [0019]    When in the VC mode of operation, a user must actuate a portion of the gripping device to close the jaws of the device. This allows the user to determine the pinch or compressive force to apply to an object. However, if the user discontinues applying the force, the jaws of the device will normally return to the default position and release the grip on a held object. 
         [0020]    In one embodiment, the gripping device may include a movable jaw and a fixed jaw. In other embodiments, the gripping device may include any number and/or combination of movable jaws and fixed jaws. In all embodiments, the gripping device can easily switch between the VO and VC modes of operation by a variety of switching mechanisms. In one embodiment, the movable jaw may open or close while the fixed jaw remains stationary regardless of which mode of operation is selected. 
         [0021]    The gripping device may also be used as a prehensor device. In various embodiments, the gripping device may be used as a prosthetic hand or terminal device. Moreover, the gripping device may also be used as or incorporated into tools, such as pliers and wrenches. 
         [0022]    Referring now to  FIGS. 1-3 , an embodiment of the gripping device, designated  100 , is shown. In some embodiments, the gripping device  100  may include a main body  102  that includes a fixed jaw  104  and recessed section  106 , positioned adjacent to the fixed jaw  104 , for receiving a movable jaw  108 . 
         [0023]    The moveable jaw  108  is rotatably engaged to the main body  102  at a pivot joint  110 . In some embodiments, the moveable jaw  108  can be connected to the main body  102  using any suitable fastening means or fastening arrangement, including but not limited to a pin  112 , such that movable jaw may rotate towards and away relative to the fixed jaw  104  about the pivot joint  110 . 
         [0024]    The moveable jaw  108  includes a drive joint  112  that is used to operatively link the moveable jaw  108  with a drive handle  114  through a mechanism, such as a connecting link  116 . For example, a distal end  118  of the connecting link  116  is engaged to drive joint  112 , such that lateral translation of the connecting link  116  causes the moveable jaw  108  to pivot about the pivot joint  110 . In some embodiments, the proximal end  120  of the connecting link  116  is engaged to a switch assembly  122  of the drive handle  114 . As such, rotation or other movement of the drive handle  114  causes the lateral translation of the connecting link  116 , which in turn causes the movable jaw  108  to pivot. In various other embodiments, the mechanism illustrated by the connecting link  116  may be hydraulically powered or cable-driven. 
         [0025]    The drive handle  114  acts as an actuation handle that switches the gripping device  100  between the voluntary-open and voluntary-close modes of operation. In one embodiment, the drive handle  114  may be actuated using a Bowden cabling system known in the art. In other embodiments, that drive handle  114  may be actuated by any other means to impart a mechanical force on the drive handle  114 . The drive handle  114  is rotatably engaged to the main body  102  through a pivot  136 . In various embodiments, a spring (not shown) is connected between pins  132  and  134  to apply a biasing force on the drive handle  114  that returns the drive handle  114  to a default position. In other embodiments, alternative equilibrium arrangements, including but not limited to those that use torsion springs or magnets, may be used to maintain a default equilibrium of the movable jaw  108  or the drive handle  114 . In addition, the magnitude of the forces exerted by the movable jaw  108  in the different modes of operation could be modified by varying the attachment locations of any biasing springs (not shown), or by the use of one or more additional springs. 
         [0026]    In one embodiment, the switch assembly  122  of the drive handle  114  may be a bi-stable switch that includes a position knob  124 , a vertical linear guide  126 , and a horizontal linear guide  128 . The vertical guide  124  is constrained to move vertically within a channel  130  of the switch assembly  122 , while the horizontal linear guide  128  is constrained to move horizontally within the channel  130 . A magnet  132  embedded in the drive handle  114  exerts a force that is proportional to the distance defined by the channel  130  on the horizontal linear guide  128  relative to the switch assembly  122 . The force exerted by the magnet  132  provides stability to minimize undesired movement of the switch assembly  122  while defining two stable orientations for the orientation of the position knob  124 . The position knob  124  is therefore movable between a “vertical up” orientation and a “vertical down” orientation. 
         [0027]    In other embodiments, the switch assembly  122  may be a reciprocating switch mechanism, such as those used in retractable ballpoint pens or the switch assembly may use bicycle-indexed gear shifters to achieve the bi-stable positions of the connecting link  116 . 
         [0028]    The orientation of the position knob  124  determines the direction of motion for the connecting link  116  when the drive handle  114  is actuated. As such, the orientation of the position knob  124  determines the mode of operation for the gripping device  100 . 
         [0029]    Referring now to  FIG. 4 , the mode of operation will determine whether force applied to the drive handle  114  will cause the movable jaw  108  to open or rotate away, as indicated by arrow  204 , from the fixed jaw  104 , as shown in the voluntary-open mode of operation at positions  200 A and  200 B. Conversely, when the mode of operation for the gripping device  100  is in a voluntary-close mode of operation, shown at positions  202 A and  202 B, actuation of the drive handle  114  will cause the movable jaw  108  to close or rotate towards the fixed jaw  104 , as indicated by arrow  206 . 
         [0030]    A conceptual depiction of the translation of one embodiment of a linkage system  300  is shown in  FIGS. 5-7 . An intermediate link  302 , which is used to illustrate the translation of the connecting link  116 , is pivotally engaged to an input link  304 , which is used to illustrate the input force applied by actuation of the drive handle  114  at a first pivot point  308 . The intermediate link  302  is also pivotally engaged to a drive link  306 , at a second pivot point  310 . The drive link  306  is used to illustrate the motion of the movable jaw  108 . As such,  FIGS. 5-7  depict the motion of the links through a singularity  318 , such that on either side of the singularity  318 , the motion of the drive link  306  varies in response to the same motion of the input link  304 . In  FIGS. 5-7 , the singularity  318  refers to a point within the linkage system  300 , wherein the motion of the drive link  306  on one side of the singularity  318  is different in response to the same motion of the input link  304  on the other side of the singularity  318 . 
         [0031]    Similar to the limited motions of the connecting link  116  and the drive handle  114 , in one embodiment, the input link  304  is constrained to vertical movement, while the drive link  306  is constrained to horizontal movement. 
         [0032]      FIG. 5  illustrates the linkage system  300  on one side of the singularity  318 . When a force  312  is applied to the input link  304 , the resulting translation of the drive link  306 , is an upward vertical motion  314 . Similarly,  FIG. 6  illustrates the motion of the linkage system  300  on the other side of the singularity  318 . As shown, when the force  312  is applied to the input link  304 , the resulting translation of the drive link  306  is a downward vertical motion  316 . The different orientations of the intermediate link  302  correspond to the different orientations of the position knob  124  within the switch assembly  122 , which corresponds to the different modes of operation for the gripping device  100 . As shown, the applied force  312  is often in the same direction, but the resulting motion and orientation of the drive link  306  may differ.  FIG. 7  illustrates the linkage system  300  at the point of singularity  318 . As such, when the force  312  is applied to the input link  304 , the drive link  306  may move in either the upward vertical motion  314  or the downward vertical motion  316 . 
         [0033]      FIGS. 8-9  illustrate the gripping device  100  in the voluntary-open mode of operation configuration  400  and the voluntary-close mode of operation configuration  500 , respectively. In particular, the orientation of the connecting link  116  relative to the drive handle  114  in each mode of operation is shown. Referring to  FIG. 8 , the proximal end of the connecting link  116  is positioned at a lower region  402  of the channel  130  within the drive handle  114 . When the drive handle  114  is actuated, the connecting link  116  moves generally towards the fixed jaw  104 , as indicated by arrow  404 . This causes the movable jaw  108  to pivot about pivot point  110  and open away from the fixed jaw  104 . 
         [0034]    Conversely, as shown in  FIG. 9  the proximal end of the connecting link  116  is positioned at an upper region  502  of the channel  130  within the drive handle  114 . When the drive handle  114  is actuated, the connecting link  116  moves generally away the fixed jaw  104 , as indicated by arrow  504 . This action causes the movable jaw  108  to pivot about pivot point  110  and close towards the fixed jaw  104 . As shown, the starting position and orientation of the drive handle  114  does not differ between the two modes of operation. The change between each mode of operation or the singularity, as shown in  FIGS. 5-7 , occurs when the distal end  118  of the connecting link  116  pass through the pivot  136 . 
         [0035]    It should be understood from the foregoing that, while particular embodiments have been illustrated and described, various modifications can be made thereto without departing from the spirit and scope of the invention as will be apparent to those skilled in the art. Such changes and modifications are within the scope and teachings of this invention as defined in the claims appended hereto.