Location: Cambridge, MA | 06/2022 - 12/2022

 

As a part of my time in the Harvard Biodesign Lab, I designed and implemented mechanical and functional improvements for components of a wearable ankle exosuit targeting the rehabilitation of post-stroke users who exhibit hemi-paretic walking.

 

These particular components were part of the primary actuated pulley mechanism of the device, and involved significant modifications to this pulley mechanism. These were primary load-bearing components that at the time, were failing critically and often during testing campaigns with humans in and out of the loop. The root cause of these issues was examined and found to be the specific geometry of the pulley disk which was transferring torque/force between the ankle portion and actuating foot plate of the device. Both the geometry and material choice were evaluated using both static tensile tests in an isolated test bench mean to mimic similar loads that these device components would experience under normal device operation, and cyclic fatigue test were also performed to see part performance over hundreds and thousands of load cycles.

 

The housing for this force-transferring pulley disk was also redesigned to a clam-shell design, simplifying the assembly process, and allowing for easier maintenance upon part failure. Alongside purely mechanical changes, a new off-axis encoder for the pulley disk was swapped in, which replaced the previous on-axis encoder that added unnecessary bulk/cross section to the device, leading to snagging cables, and excessive hazard during previous testing. The integration of this new encoder also involved mechanical changes to both the pulley disk and the housing, and afterwards an oscilloscope was used to calibrate and validate the functionality of the encoder was integrated into the assembly.