Lower extremity exoskeleton for gait retraining

Abstract

The Active Knee Rehabilitation Orthotic System (ANdROS) is a wearable and portable assistive tool for gait rehabilitation and monitoring of people with motor control deficits due to a neurological ailment, such as stroke. ANdROS reinforces a desired gait pattern by continually applying a corrective torque around the knee joint, commanded by a impedance controller. A sensorized yet unactuated brace worn on the unimpaired leg is used to synchronize the playback of the desired trajectory based on the user's intent. The device is mechanically grounded through two ankle foot orthoses (AFOs) rigidly attached to the main structure, which helps reduce the weight perceived by the user.

What is claimed is: 
     
         1 - 15 . (canceled) 
     
     
         16 . A computer implemented method of computing a desired joint angle estimate comprising the steps of:
 measuring at least one gait related physiological parameter of a patient;   estimating the gait phase based on at least the one gait related physiological parameter;   estimating the cadence based on at least the one gait related physiological parameter;   selecting a new reference gait trajectory based on at least the estimated cadence; and   computing a desired joint angle based on the estimated gait phase and the new reference trajectory.   
     
     
         17 . The method of  claim 16  wherein the gait phase estimate is computed by minimizing the function: 
       
         
           
             
               
                 f 
                  
                 
                   ( 
                   ϕ 
                   ) 
                 
               
               = 
               
                 
                   ∑ 
                   
                     i 
                     = 
                     1 
                   
                   N 
                 
                  
                 
                     
                 
                  
                 
                   
                     
                       w 
                       i 
                     
                      
                     
                       ( 
                       
                         ϕ 
                         _ 
                       
                       ) 
                     
                   
                    
                   
                      
                     
                       
                         
                           x 
                           i 
                           * 
                         
                          
                         
                           ( 
                           ϕ 
                           ) 
                         
                       
                       - 
                       
                         x 
                         i 
                       
                     
                      
                   
                 
               
             
           
         
         where φ is the gait phase, N is the number of measurements employed, w is the weighing function,  φ  is the estimated gait phase from the previous calculation, is the value of the pre-recorded trajectory corresponding to the gait phase, and x is the measurement of the particular parameter. 
       
     
     
         18 . The method of  claim 17  further comprising variable weighting functions. 
     
     
         19 . The method of  claim 17  wherein the functions are weighed proportionally with the absolute value of their derivatives. 
     
     
         20 . The method of  claim 16  wherein the gait related physiological parameter is one of the hip angle, the knee angle, and the vertical hip position. 
     
     
         21 . The method of  claim 17  wherein the measured parameter is at least one of the hip angle, the knee angle, and the vertical hip position.