Design of a High Bandwidth Actuation for Seamless Assistance in Walking and Running

To date, the majority of robotic assistive devices designed for lower limb support are tailored for either walking or running, with minimal exploration into devices capable of accommodating both activities. This discrepancy stems from the inherent differences in movement frequencies between walking and running, necessitating actuation systems with sufficient bandwidth to handle both tasks effectively. The challenge lies in addressing the faster reversal of electromechanical actuators' direction that accompanies increased frequencies. To tackle this challenge, our work introduces a novel underactuated actuation mechanism based on the Tusi Couple, specifically designed to support both walking and running in robotic assistive devices. This mechanism is designed to produce alternating motor motion at lower step frequencies associated with walking, and continuous motion at higher step frequencies associated with running, thereby minimizing delays related to motion alternation. In both cases, the mechanism converts the mentioned rotary movements of the motor into alternating linear movement of a slider as output. By aligning the mechanism's motion with the cyclic nature of human locomotion, our results suggest potential for providing timely assistance to human lower limbs. Upon integration into an embedded robotic wearable device, this actuation mechanism holds promise as a unified solution for assisting all human locomotion modes.