Effect of Increased Propulsion on Step Length on an Adaptive Split-belt Treadmill

• Sophia Burrowes, Biomedical Engineering, University of Delaware

• Jill Higginson, Mechanical Engineering, University of Delaware

Currently, treadmills are used in rehabilitation but only run at fixed speeds, preventing instantaneous changes in gait for users. An adaptive  split-belt treadmill (ATM) can change speeds based on users’ gait mechanics. Previous studies have suggested that an ATM (that changes speed using the user’s  propulsion, step length and position) can increase propulsion for young healthy participants. 

For this study, the ATM was modified to update each belt speed independently based on the individual limbs using a custom-written Matlab code. To increase propulsion force on the ATM, one belt was preferentially weighted while maintaining a user’s self-selected walking speed. This study observed the effects of increased propulsion requirements on step length on an ATM for five trials. The conditions were Normal (propulsive feedback is similar to overground walking), Hard (requires more propulsion for the same speed as Normal), and Split Preferential (Belt1= Normal, Belt 2= Hard). Two trials (Normal and Hard) were conducted in Tied mode where both belts updated to match the user’s speed. The last three trials were in Split mode (Normal, Hard, SplitPref) where each leg would change the speed of its respective belt. Data from fourteen young healthy participants was analyzed using custom MATLAB code.

The results showed that Hard Trials step length were higher for all conditions which was in line with the alternate hypothesis.  For the Split Preferential condition, the Normal belt step length was shorter than the Hard belt which was opposite of what was hypothesized. 

Our results could contribute to the understanding of how an ATM changes a person’s gait and hopefully will contribute to optimizing an ATM for rehabilitation.