Designing bionic path robots to minimize the metabolic cost of human movement

Despite great successes in wearable robotics, designing assistive devices that are portable like clothes and could reduce the metabolic cost of human movement remains a substantial challenge. Inspired by the driving mechanism of human body, we proposed a class of bionic path (BP) robots in this paper. The BP robots could assist human limbs along arbitrary paths predesigned on the limb surface, and could be driven by various soft path actuators (the active, quasi-active or passive). Additionally, to minimize the metabolic cost of human movement, a human-in-the-loop optimization method for designing BP robots was also developed in this paper. As practical examples, 18 BP robots with 3 different types of path actuators along 6 different paths were designed to help people reduce their metabolic cost during walking. Each of the 18 robots combined with the human body separately to form a coupled dynamic system. The metabolic power, muscle excitations and optimal control profiles for these coupled systems were analyzed using the simulation-based method. Simulation results showed that, 13 of these 18 BP robots decreased the whole-body metabolic energy consumption, and the maximum reduction was up to 55% relative to the unassisted scenarios.