A Method of Swing Leg Control for a Minimally Actuated Medical Exoskeleton for Individuals With Paralysis

Abstract

This paper discusses the control of a medical exoskeleton swing leg that has a “passive” (unactuated) knee. Previous work in legged locomotion has demonstrated the feasibility of achieving natural, energy efficient walking with minimally actuated robotic systems. This work will present early results for a medical exoskeleton that only has actuation that powers the flexion and extension of the biological hip. In this work, a hybrid model of the state dependent kinematics and dynamics of the swing leg will be developed and parameterized to yield swing hip dynamics as a function of desired knee flexion dynamics. This model is used to design swing hip motions that control the flexion behavior of the passive swing knee in a human-like manner. This concept was tested by a paraplegic user wearing a new minimally actuated exoskeleton. The presented results show that a human-like swing phase can be achieved with an exoskeleton that has fewer actuated degrees of freedom than current medical exoskeletons.

H-infinity Based Full State Feedback Controller Design for Human Swing Leg

“…A better robustness was obtained from the LQR controller. The test was done on the robot leg from -11.5 0 to 11.5 0 and obtained high control action about 30 N.m. Reid et al [6] discussed a control and a potential efficiency of a medical exoskeleton with passive knees for enabling many individuals with paralysis to walk in a natural manner. The dynamics of the passive pendulum of the swing knee was excited and controlled via the behavior of the swing hip to control knee flexion.…”