Lightweight assistive exoskeletons have incredible potential to improve quality of life for those with mobility impairments such as sarcopenia and osteoarthritis [MedranoRouseThomas2021TMRB]; however, several challenges are hindering their translation to the home and workplace. One key limitation is that assistive exoskeleton control strategies are predicated on only operating in a small, fixed set of tasks (e.g., walking, stair ascent, etc.). This limitation prevents exoskeletons from handling the broad scope of locomotion modes—and the fluid transitions between them—that are essential for activities of daily living.
A task-invariant control framework is therefore needed to develop practical exoskeleton technology that can assist humans in their everyday lives. This framework needs to be able to recognize human intent without assuming a pattern in their behavior, and to address this point I proposed to use shoe-sole force/torque sensors in conjunction with inertial measurement units to estimate the human’s joint torques directly from the physics of the human body [ThomasGregg2021CDC]. In this research direction, my aims are to (1) establish a theoretical framework for the stable control and energetic passivity properties of exoskeletons using joint torque estimates inferred from ground reaction force sensor, (2) design and build a lightweight backdrivable hip-knee-ankle exoskeleton similar to the M-BLUE modular orthosis [NeslerThomasDivekarRouseGregg2021RAL] and a force sensing shoe, and (3) determine the extent to which wearers can perceive the amplification bandwidth of the exoskeleton (a potential performance benchmark for task-invariant controllers) using a psychophysical experiment. As it addresses a fundamental gap in robotics capabilities, this research aligns with the goals of the NSF CMMI program on Foundational Research in Robotics. Successful strength amplification would both reduce muscle tension and, depending on the mechanical design of the exoskeleton, apply loads to the joints in proportion to the applied torque [MedranoRouseThomas2021TMRB]. Both of these effects could be exploited to alter joint loading in beneficial ways, and their optimization is a potential collaboration opportunity with biomedical researchers interested in osteoarthritis.
Human-Empowering Robotics and Control (HERC) Lab
Empowering Humans with Robots
