Elastic load suspension

Abstract

Elastic load suspension systems and methods are disclosed. Embodiments include handles with springs to reduce peak forces and reduce the overall energy required to carry a load. Some embodiments include handles that connect to loads, where the effective spring length statically deflects at least 2.5 and at most 18 inches, and in some embodiments approximately 5 inches, when carrying the load. Alternate embodiments include elastic suspension handles that are lightly damped, such as those with a damping ratio of at most 0.5. Still further embodiments include elastic suspension handles that elastically suspend loads and have a natural frequency that is less than the locomotive frequency of the object carrying the handle, such a less than the typical human walking frequency of 2 Hertz.

What is claimed is: 
     
         1 . A carrying handle, comprising:
 a grip portion;   a connecting member for connecting the grip portion to a load; and   a spring connected to the grip portion and to the connecting member, wherein the effective spring length statically deflects at least 2.5 and at most 18 inches when carrying the load.   
     
     
         2 . The carrying handle of  claim 1 , wherein the effective spring length statically deflects at least 4 inches and at most 10 inches when carrying the load. 
     
     
         3 . The carrying handle of  claim 1 , wherein the effective spring length statically deflects 5 inches when carrying the load. 
     
     
         4 . The carrying handle of  claim 1 , wherein the spring is pretensioned and the physical displacement between the handle and the carried object is reduced. 
     
     
         5 . The carrying handle of  claim 1 , wherein the natural frequency of the spring is less than 2 Hertz. 
     
     
         6 . The carrying handle of  claim 1 , wherein the damping ratio of the carrying handle is at most 0.5. 
     
     
         7 . The carrying handle of  claim 1 , wherein the stiffness of the spring is adjustable by the user. 
     
     
         8 . The carrying handle of  claim 1 , wherein the spring is a nonlinear spring. 
     
     
         9 . The carrying handle of  claim 1 , wherein the spring is a leaf spring, a torsion spring, a coil spring, an air spring, an elastic cord, an elastic band, or a compliant plastic mechanism. 
     
     
         10 . The carrying handle of  claim 1 , comprising:
 a locking mechanism with at least two user selectable configurations including
 a rigid suspension configuration, wherein the spring is restrained from deflecting, and 
 an elastic suspension configuration, wherein the spring deflects when carrying the load. 
   
     
     
         11 . A method for carrying a load, comprising:
 extending the effective length of a spring connected to a handle and a load, the effective spring length extending at least 2.5 inches and at most 18 inches;   suspending the load below the extended handle;   lightly damping oscillations of the suspended load with a damping ratio equal to at most 0.5.   
     
     
         12 . The method of  claim 11 , wherein said extending extends the effective length of the spring at least 4 and at most 10 inches. 
     
     
         13 . The method of  claim 11 , wherein said extends the effective length of the spring 5 inches. 
     
     
         14 . The method of  claim 11 , wherein said lightly damping is accomplished with a damping ratio equal to at most 0.1. 
     
     
         15 . The method of  claim 11 , comprising:
 restricting non-vertical motion of the suspended load.   
     
     
         16 . The method of  claim 11 , comprising:
 extending the load below the handle and reaching a static equilibrium point approximately 5 inches below the handle.   
     
     
         17 . A method of manufacturing a handle, comprising:
 selecting an elastic member that will have an effective static deflection of at least 2.5 inches and at most 18 inches when a predetermined load is suspended by the elastic member;   connecting the elastic member to a grip adapted for grasping; and   connecting the elastic member to a load attachment portion, the load attachment portion including a mechanism for attaching to the predetermined load.   
     
     
         18 . The method of  claim 17 , wherein said selecting includes selecting an elastic member that will have an effective static deflection of at least 4 inches and at most 10 inches when the predetermined load is suspended by the elastic member 
     
     
         19 . The method of  claim 17 , wherein said selecting includes selecting an elastic member that will have an effective static deflection of approximately 5 inches when the predetermined load is suspended by the elastic member 
     
     
         20 . The method of  claim 17 , comprising:
 selecting an elastic member that will have a damping ratio of at most 0.5 when connected to the grip and the load attachment portion and suspending the predetermined load.