Control of a robotic orthosis for gait rehabilitation

• This paper presents new experimental results with an intrinsically compliant robotic gait training orthosis.
• A trajectory tracking controller implemented to guide the subject’s limbs on physiological gait trajectories.
• The compliance of the robotic orthosis was also controlled, independently of the trajectory control.
• The robotic orthosis and the control scheme were evaluated on healthy subjects.

Robot assisted gait training may help in producing rapid improvements in functional gait parameters. This paper presents new experimental results with an intrinsically compliant robotic gait training orthosis. The newly developed robotic orthosis has 6 degrees of freedom (DOFs). A trajectory tracking controller based on the boundary layer augmented sliding control (BASMC) law was implemented to guide the subject’s limbs on physiological gait trajectories. The compliance of the robotic orthosis sagittal plane hip and knee joints was also controlled, independently of the trajectory tracking control. The robotic orthosis and the control scheme were evaluated on three neurologically intact subjects walking on a treadmill. A maximum trajectory tracking error of 10° was recorded at the hip and knee sagittal plane joints. The results showed that subjects can walk in the robotic orthosis with comfort and the BASMC law was able to guide the subject’s limbs on reference physiological trajectories.