Musculoskeletal simulations reveal the metabolic benefits of assistive strategies that couple multiple degrees-of-freedom

Human-in-the-loop optimization is a powerful strategy for customizing exoskeleton assistance for an individual, but optimization of many control parameters becomes resource-intensive. We used simulations to determine if coupling assistance between lower-limb degrees-of-freedom (DOFs) could produce larger metabolic savings than assisting at a single DOF, while keeping the parameter space small. Three of the four coupled hip, knee, and/or ankle assistance strategies produced greater metabolic savings compared to single DOF assistance and only required one or two additional parameters in the optimization. Coupling DOFs could thus improve metabolic savings without adding a large time cost during human-in-the loop optimization trials.