Date of Award

Summer 8-2019

Document Type


Degree Name

Master of Science in Mechanical Engineering (MSME)


Mechanical Engineering

First Advisor

Winck, Ryder

Second Advisor

Rogge, Renee

Third Advisor

Berry, Carlotta


A supernumerary robotic limb (SRL) is a robotic limb that can act as an extra arm or leg for a human user. An unsolved issue with SRLs is how to operate them well. One possibility is to control an SRL with the foot, which offers the benefit of a third arm because the user’s arms remain unoccupied. While hand interfaces are common, foot interfaces are not well understood. Developing a good foot interface is challenging because of differences between feet and hands, such as the larger inertia of the leg. This thesis presents work to determine some design principles for foot interfaces. First, an experiment is done to test if the addition of friction to a foot interface can improve performance. The results show that friction can help a user stop and hold position without reducing the dynamic performance of the user. A second experiment looks at the performance of isometric interfaces, which, unlike isotonic interfaces, use force inputs rather than motion. Isotonic interfaces generally outperformed isometric, although there were only small differences between rate control for both isotonic and isometric. Additionally, rate control was found to be better than position control for the isometric interface. Finally, an experiment was conducted to evaluate how well a human user can use a foot-controlled SRL to coordinate motion with both of their hands. People showed that they could reliably use their foot in conjunction with their hands to perform a two-dimensional positioning task better than they can with just two hands, and with performance resembling that of two human users.