A Novel Mechanism and Method for Application of Force Impulses in Cable-Based Rehabilitation Systems

The rapidly aging population is anticipated to lead to an increased incidence of age-related diseases, with stroke being a prominent health concern among the elderly. Post-stroke individuals often exhibit hemiplegic gait, characterized by spatial and temporal asymmetry, posing challenges to mobility and increasing the risk of falls. Traditional rehabilitation methods involve manual physiotherapy, which is time-consuming and resource-intensive. Recent advancements in rehabilitation robotics offer a promising solution to augment conventional gait rehabilitation. This paper introduces a novel cable-based mechanism designed to enhance transparency during robot-assisted gait training. Unlike conventional cable-driven robots, the proposed mechanism mechanically decouples the cable from the actuator when no intervention is required, minimizing undesired characteristics such as friction and inertia transfer to the user. This design aims to improve the transparency of the mechanism, allowing for a more natural interaction between the user and the rehabilitation robot. Our goal was to evaluate the quality of transparent mode of the proposed mechanism. This was carried out by investigating cable tension forces as well as possible adaptations in the dynamics of center of pressure and ground reaction force, gait kinematics, and muscle activation patterns during continuous transparent mode of operation as well as in swing assistance and resistance, where the mechanism must rapidly switch between transparent and actuation modes of operation. Results show that the proposed mechanism demonstrated high mechanical transparency whenever used in transparent mode of operation, and was able to transition swiftly between transparent and actuation modes during swing assistance and resistance.