Design and evaluation of an adjustable step size trajectory generator for the Symbitron exoskeleton with spinal cord injury users

This study introduces a controller design and trajectory generator for the Symbitron Exoskeleton, tailored for individuals with spinal cord injuries (SCI). The trajectory generator offers three types of trajectories: fixed, adjustable, and partly adjustable, enabling users to modify step sizes during gait, crucial for tasks like the Cybathlon 2024's 'Stones' challenge. The enhanced system allows pilots to select from various step sizes, computed by the trajectory generator and smoothly integrated via polynomials in the controller. Two experiments with a healthy male participant demonstrated superior performance of fixed and adjustable libraries over the partly adjustable one, meeting accuracy, precision, task load, and time requirements. Recommendations include refining joint angle tracking, torque regulation, and diversifying size options, with potential validation through future experiments involving SCI patients. Overall, this implementation empowers pilots to choose step sizes, thereby enhancing the functionality and accessibility of the Symbitron exoskeleton for SCI individuals.