Device for translating a force including a focused groove

Abstract

A device to change the direction or point of application of a force comprises a body having an axis, a groove formed within the body so that the groove has a helical shape along at least a portion of the axis, the groove adapted to receive a cable, wherein a helical angle of the groove varies so that a tangent of the helical angle along the groove substantially intersects a single point remote from the body.

1 . A device to change the direction or point of application of a force, the device comprising:
 a body having an axis;   a groove formed within the body so that the groove has a helical shape about at least a portion of the axis, the groove adapted to receive a cable connectable with a target remote from the body;   wherein a helical angle of the groove varies so that when the groove receives the cable, a tangent of the helical angle along the groove at a point where the cable disassociates from the groove substantially intersects the target.   
     
     
         2 . The device of  claim 1 , wherein a first portion of the groove includes a first helix shape and a second portion of the groove includes second helix shape;
 wherein the cable is connectable with a second target remote from the body;   wherein a helical angle of the first portion of the groove varies so that a tangent of the helical angle along the first portion of the groove at a point where the cable disassociates from the first portion of the groove substantially intersects the first target;   wherein a helical angle of the second portion of the groove varies so that a tangent of the helical angle along the second portion of the groove at a point where the cable disassociates from the second portion of the groove substantially intersects the second target.   
     
     
         3 . The device of  claim 1 , wherein the groove is an output groove adapted to receive an output cable; and further comprising:
 an input groove formed within the body so that the input groove has a helical shape along at least a portion of the axis, the input groove adapted to receive an input cable connectable with a second target remote from the body;   wherein a helical angle of the input groove varies so that a tangent of the helix angle along the input groove at a point where the input cable disassociates from the input groove substantially intersects the second target.   
     
     
         4 . The device of  claim 3 , wherein a proximal end of the input cable is fixedly associated with the body and a proximal end of the output cable is fixedly associated with the body. 
     
     
         5 . The device of  claim 3 , further comprising a pocket disposed within the body;
 wherein a proximal end of one or both of the input cable and the output cable includes a crimp receivable within the pocket.   
     
     
         6 . The device of  claim 2 , wherein the body is a pulley. 
     
     
         7 . The device of  claim 3 , wherein the body is a capstan. 
     
     
         8 . A device to change the direction or point of application of a force, the device comprising:
 a body having an axis;   an input groove formed within a first portion of the body so that the input groove has a helical shape about the axis, the input groove adapted to receive an input cable;   wherein a helical angle of the input groove varies so that a tangent of the helical angle along the input groove at a point where the input cable disassociates from the groove substantially intersects a first target remote from the body; and   an output groove formed within a second portion of the body so that the output groove has a helical shape along the axis, the output groove adapted to receive an output cable;   wherein a helical angle of the output groove varies so that a tangent of the helical angle along the output groove at a point where the input cable disassociates from the groove substantially intersects a second target remote from the body.   
     
     
         9 . The device of  claim 8 , wherein the input groove is adapted to receive an input cable and the output groove is adapted to receive an output cable. 
     
     
         10 . The device of  claim 8 , wherein a cable is received within the input groove and the output groove. 
     
     
         11 . The device of  claim 8 , wherein a proximal end of the input cable is fixedly associated with the body and a proximal end of the output cable is fixedly associated with the body. 
     
     
         12 . The device of  claim 9 , further comprising a pocket disposed within the body;
 wherein a proximal end of one or both of the input cable and the output cable includes a crimp receivable within the pocket.   
     
     
         13 . The device of  claim 8 , wherein the body is a pulley. 
     
     
         14 . The device of  claim 8 , wherein the body is a capstan. 
     
     
         15 . A spring system having an adjustable spring constant, comprising:
 an end plug including a helical groove in a face of the end plug having a helix-angle that varies parabolically;   a helical extension spring;   said end plug is adapted to be mated with the helical extension spring so that the coil of the helical extension spring is received in the helical groove; and   a cable connected to the end plug, wherein when the cable is placed in tension by a load, the face of the end plug is urged against the coil of the helical extension spring;   wherein a counter force applied by the helical extension spring in response to the load is adjustable by repositioning the end plug along the helical extension spring.   
     
     
         16 . The spring system of  claim 15 , wherein the helix-angle of the helical groove decreases relative to a fixed location along the coil and within the helical groove as one or both of the coil of the helical extension spring and the end plug is adjusted to increase the counter force applied by the helical extension spring. 
     
     
         17 . The spring system of  claim 15 , wherein:
 the helical groove is a first helical groove and the face is a first face; and   the end plug further includes a second helical groove in a second face opposite the first face, the second groove having a helix-angle that varies parabolically; and   
       when the end plug is mated with the helical extension spring, the coil of the helical extension spring is guided from the first helical groove to the second helical groove. 
     
     
         18 . The spring system of  claim 17 , wherein:
 the helix-angle of the first helical groove decreases relative to a first fixed location along the coil and within the first helical groove and the helix-angle of the second helical groove increases relative to a second fixed location along the coil and within the second helical groove as one or both of the coil of the helical extension spring and the end plug is adjusted to increase the counter force applied by the helical extension spring.   
     
     
         19 . The spring system of  claim 15 , wherein the cable is an input cable, and wherein the spring system further comprises:
 a pulley including an input groove and an output groove;   the input cable having a first end coupled to the input groove and a second end connected with the end plug;   an output cable having a first end coupled to the output groove and a second end extending from the first end;   wherein the pulley is adapted to transfer a counter-balance force to the second end of the output cable.