Adjustable surface stiffness treadmill

Abstract

A treadmill with adjustable vertical surface stiffness is disclosed. The treadmill is used to study gait adaptation and develop interventions for gait rehabilitation for conditions such as stroke. The surface stiffness is set by controlling the length of a cantilever beam which acts as an adjustable stiffness spring suspension underneath the treadmill. The treadmill also contains an additional novel mechanism to reduce the amount by which it is allowed to sag under its own weight as the stiffness decreases.

What is claimed is: 
     
         1 . An adjustable stiffness treadmill, comprising:
 a first treadmill motor;   a first treadmill driven by the first treadmill motor, the first treadmill having a linear guide permitting vertical movement of the first treadmill and limiting lateral movement of the first treadmill;   a cantilever beam supporting the first treadmill; and   a support mechanism supporting the cantilever beam, the support mechanism positionable about the length of the cantilever beam whereby the spring tension of the cantilever beam may be selectively stiffened.   
     
     
         2 . The device of  claim 1 , wherein the support mechanism comprises a rack and pinion mechanism configured and arranged to adjust the position of the support mechanism about the cantilever beam. 
     
     
         3 . The device of  claim 1 , wherein the support mechanism comprises a plurality of cantilever constraint rollers contacting the cantilever beam. 
     
     
         4 . The device of  claim 1 , wherein the cantilever beam comprises a cantilever spring. 
     
     
         5 . The device of  claim 1 , further comprising:
 a preload mechanism configured and arranged to reduce sag in the first treadmill.   
     
     
         6 . The device of  claim 1 , further comprising:
 a second treadmill motor; and   a second treadmill driven by the second treadmill motor;   the second treadmill positioned adjacent and parallel to the first treadmill, whereby a subject's left leg and right leg are on separate treadmills when in use.   
     
     
         7 . The device of  claim 1  further comprising a plurality of motion capture cameras positioned around the first treadmill. 
     
     
         8 . The device of  claim 6 , further comprising a plurality of motion capture cameras positioned around the first treadmill and second treadmill. 
     
     
         9 . An adjustable stiffness treadmill, comprising:
 a first treadmill motor;   a first treadmill driven by the first treadmill motor, the first treadmill having a linear guide permitting vertical movement of the first treadmill and limiting lateral movement of the first treadmill;   a cantilever beam supporting the first treadmill;   a support mechanism supporting the cantilever beam, the support mechanism positionable about the length of the cantilever beam whereby the spring tension of the cantilever beam may be selectively stiffened;   a second treadmill motor; and   a second treadmill driven by the second treadmill motor;   the second treadmill positioned adjacent and parallel to the first treadmill, whereby a subject's left leg and right leg are on separate treadmills when in use.   
     
     
         10 . The device of  claim 9 , wherein the support mechanism comprises a rack and pinion mechanism configured and arranged to adjust the position of the support mechanism about the cantilever beam. 
     
     
         11 . The device of  claim 9 , wherein the support mechanism comprises a plurality of cantilever constraint rollers contacting the cantilever beam. 
     
     
         12 . The device of  claim 9 , wherein the cantilever beam comprises a cantilever spring. 
     
     
         13 . The device of  claim 9 , further comprising:
 a preload mechanism configured and arranged to reduce sag in the first treadmill.   
     
     
         14 . The device of  claim 9 , further comprising a plurality of motion capture cameras positioned around the first treadmill and second treadmill. 
     
     
         15 . An adjustable stiffness treadmill, comprising:
 a first treadmill motor;   a first treadmill driven by the first treadmill motor, the first treadmill having a linear guide permitting vertical movement of the first treadmill and limiting lateral movement of the first treadmill;   a cantilever beam supporting the first treadmill;   a support mechanism supporting the cantilever beam, the support mechanism positionable about the length of the cantilever beam whereby the spring tension of the cantilever beam may be selectively stiffened; and   a preload mechanism configured and arranged to reduce sag in the first treadmill.   
     
     
         16 . The device of  claim 15 , wherein the support mechanism comprises a rack and pinion mechanism configured and arranged to adjust the position of the support mechanism about the cantilever beam. 
     
     
         17 . The device of  claim 15 , wherein the support mechanism comprises a plurality of cantilever constraint rollers contacting the cantilever beam. 
     
     
         18 . The device of  claim 15 , wherein the cantilever beam comprises a cantilever spring. 
     
     
         19 . The device of  claim 15 , further comprising:
 a second treadmill motor; and   a second treadmill driven by the second treadmill motor;   the second treadmill positioned adjacent and parallel to the first treadmill, whereby a subject's left leg and right leg are on separate treadmills when in use.   
     
     
         20 . The device of  claim 15 , further comprising a plurality of motion capture cameras positioned around the first treadmill. 
     
     
         21 . The device of  claim 19 , further comprising a plurality of motion capture cameras positioned around the first treadmill and second treadmill.