End-effector jaw closure transmission systems for remote access tools

Abstract

A jaw closure transmission system is presented comprising an input sub-system, output sub-system and a transmission sub-system.

What is claimed is: 
     
         1 . A medical device having a jaw assembly actuated by a transmission cable having a finite stiffness in a transmission direction, the device comprising:
 an elongate transmission guide, wherein the transmission cable is routed through the transmission guide;   a handle assembly at a proximal end of the elongate transmission guide, the handle assembly comprising a handle body, an input lever, a handle output coupled to the transmission cable, and a handle mechanism coupling the input lever to the handle output, wherein the handle mechanism has an input stroke consisting of a full closure displacement of the input lever relative to the handle body, further wherein the input stroke is divided into a first part and a second part, wherein the first part corresponds to a displacement of 30% to 70% of the full closure displacement of the input lever and the second part corresponds to the remaining displacement of the input lever; and   wherein the jaw assembly is distal to the elongate transmission guide, the jaw assembly having a first jaw, a second jaw, a jaw input coupled to the transmission cable, and a jaw mechanism coupling the jaw input to the second jaw, wherein the jaw mechanism has an open configuration when the first and second jaws are fully open relative to each other and a closed configuration when the first and second jaws are fully closed;   further wherein the displacement of the input lever relative to the handle body corresponding to the first part of the input stroke actuates the handle output which in turn actuates the jaw input via the transmission cable, which in turn closes the first and second jaws until the first and second jaws reach a hard stop, and thereafter the displacement of the handle lever relative to the handle body corresponding to the second part of the input stroke stretches the transmission cable, wherein the resulting tension in the transmission cable is converted by the jaw mechanism to a holding force between the first and second jaws.   
     
     
         2 . The device of  claim 1 , wherein the handle mechanism comprises a linkage or a cam. 
     
     
         3 . The device of  claim 1 , wherein the handle mechanism comprises a six-bar linkage. 
     
     
         4 . The device of  claim 1 , wherein the elongate transmission guide comprises a flexible conduit or elongate shaft or both. 
     
     
         5 . The device of  claim 1 , wherein the transmission cable has a stiffness in a transmission direction of less than 650 pounds per inch. 
     
     
         6 . The device of  claim 1 , wherein handle mechanism is configured to provide a first mechanical advantage during the first part of the input stroke and a second mechanical advantage that is greater than the first mechanical advantage during the second part of the input stroke. 
     
     
         7 . The device of  claim 1 , wherein the handle output comprises one or more of: a shuttle, a push rod, or a pull rod. 
     
     
         8 . The device of  claim 1 , further comprising a jaw base to which either or both the first and second jaws are pivotally coupled. 
     
     
         9 . The device of  claim 1 , wherein the jaw input comprises a jaw pulley, and the jaw mechanism comprises a cam surface between the jaw pulley and the second jaw. 
     
     
         10 . The device of  claim 1 , further comprising a releasable latching mechanism configured to hold the handle lever locked in a closed position at the end of the input stroke. 
     
     
         11 . A method of operating a medical device to close a jaw assembly of the medical device, wherein the medical device comprises an elongate transmission guide, a finite stiffness transmission cable within the transmission guide, and a handle assembly at the proximal end of the elongate transmission guide having an input lever and a handle mechanism coupling the input lever to the transmission cable, wherein the transmission cable is coupled to a jaw input of the jaw assembly, wherein the jaw assembly is distal to the elongate transmission guide, the method comprising:
 actuating the input lever to apply tension to the transmission cable during a first part of an input stroke of the handle assembly to close a first and second jaw of the jaw assembly from an open configuration until the first and second jaws reach a hard stop; and   continuing to actuate the input lever during a second part of the input stroke after the first and second jaws have reached the hard stop and stretching the transmission cable;   wherein the input stroke consists of a full displacement of the handle lever of the handle assembly, and further wherein the handle assembly transitions from the first part of the input stroke to the second part of the input stroke when the handle is between 30% and 70% displaced.   
     
     
         12 . The method of  claim 11 , further comprising applying a first mechanical advantage during the first part of the input stroke and applying a second mechanical advantage that is greater than the first mechanical advantage during the second part of the input stroke. 
     
     
         13 . The method of  claim 11 , further comprising grasping an object between the first and second jaws, wherein the first and second jaws reach the hard stop when the object is secured between the first and second jaws. 
     
     
         14 . The method of  claim 11 , further comprising locking the input lever in a fully closed position relative to a handle shell in the handle assembly. 
     
     
         15 . The method of  claim 11 , further comprising releasing the input lever to transition the handle lever from the second part of the input stroke to the first part of the input stroke, reducing the tension on the transmission cable and reducing the stretch of the transmission cable before translating the transmission cable so that the first and second jaws open.