Enhancing Voluntary Motion with Modular, Backdrivable, Powered Hip and Knee Orthoses
This addresses mobility deficits for individuals with disabilities, but it is incremental as it builds on existing exoskeleton concepts with modular and backdrivable improvements.
The paper tackled the problem of mobility disabilities by developing the Modular Backdrivable Lower-limb Unloading Exoskeleton (M-BLUE), which uses high-torque, low-impedance actuators on modified orthoses to assist hip and/or knee motion, resulting in reduced muscle EMG readings in able-bodied subjects during lifting tasks, with torque prediction accuracy within 0.4 Nm.
Mobility disabilities are prominent in society with wide-ranging detriments to affected individuals. Addressing the specific deficits of individuals within this heterogeneous population requires modular, partial-assist, lower-limb exoskeletons. This paper introduces the Modular Backdrivable Lower-limb Unloading Exoskeleton (M-BLUE), which implements high torque, low mechanical impedance actuators on commercial orthoses with sheet metal modifications to produce a variety of hip- and/or knee-assisting configurations. Benchtop system identification verifies the desirable backdrive properties of the actuator, and allows for torque prediction within 0.4 Nm. An able-bodied human subject experiment demonstrates that three unilateral configurations of M-BLUE (hip only, knee only, and hip-knee) with a simple gravity compensation controller can reduce muscle EMG readings in a lifting and lowering task relative to the bare condition. Reductions in mean muscular effort and peak muscle activation were seen across the primary squat musculature (excluding biceps femoris), demonstrating the potential to reduce fatigue leading to poor lifting posture. These promising results motivate applications of M-BLUE to additional subject populations such as hip/knee osteoarthritis and geriatric frailty, and the expansion of M-BLUE to bilateral and ankle configurations.