Personalized Wearable Ankle Robot Using Modular Additive Manufacturing Design

Wearable assistive robots can potentially improve the gait of individuals with reduced mobility. To address each individual's unique needs, personalized robots are necessary. In addition, robots equipped with portable systems are required to ensure their practical use in clinical and outdoor settings. We developed and evaluated a modular robotic ankle-foot orthosis (AFO) with two degrees of freedom and a portable actuation system, providing ankle plantarflexion and in/eversion assistance. The performance was evaluated via benchtop testing and human subject experiments. The benchtop testing demonstrated that the device could deliver 40 Nm of plantarflexion torque and 16 Nm of in/eversion torque, with rise times of 70 ms during plantarflexion, 84 ms during inversion, and 77 ms during eversion. The torque control bandwidth was greater than 13 Hz in plantarflexion and in/eversion. When a human subject used the device for squat assistance, the device presented its ability to track the desired torque trajectory with a maximum mean RMS error of 2.9 ± 1.2 Nm for plantarflexion assistance and 0.7 ± 0.5 Nm for in/eversion assistance. This study shows the potential of the proposed modular AFO, fabricated solely via additive manufacturing and utilizing an off-board portable actuation system. The proposed device can personalize ankle exoskeletons and examine in/eversion assistance effects for individuals with reduced mobility.