Pediatric gait rehabilitation Spreaders and guidance strategies using robotic exoskeletons require a controller that encourages user volitional control and participation while guiding the wearer towards a stable gait cycle.Virtual constraint-based controllers have created stable gait cycles in bipedal robotic systems and have seen recent use in assistive exoskeletons.This paper evaluates a virtual constraint-based controller for pediatric gait guidance through comparison with a traditional time-dependent position tracking controller on a newly developed exoskeleton system.
Walking experiments were performed with a healthy child subject wearing the exoskeleton under proportional-derivative control, virtual constraint-based control, and while unpowered.The participant questionnaires assessed the perceived exertion and controller usability measures, while sensors provided kinematic, control torque, batteries and muscle activation data.The virtual constraint-based controller resulted in a gait similar to the proportional-derivative controlled gait but reduced the variability in the gait kinematics by 36.
72% and 16.28% relative to unassisted gait in the hips and knees, respectively.The virtual constraint-based controller also used 35.
89% and 4.44% less rms torque per gait cycle in the hips and knees, respectively.The user feedback indicated that the virtual constraint-based controller was intuitive and easy to utilize relative to the proportional-derivative controller.
These results indicate that virtual constraint-based control has favorable characteristics for robot-assisted gait guidance.