Rehabilitation Exoskeleton Design: Exploring the Effect of the Anterior Lunge Degree of Freedom

As our robotics community advances its understandingtoward the optimal design of robotic exoskeletons for humangait training, the question we ask in this paper is how the anteriorlunge degree of freedom in the robotic exoskeleton affects humangait training. Answering this question requires both novel roboticdesign and novel protocols for human gait training to characterizethis effect. To the best of the authors’ knowledge, this is the firststudy to characterize the effect of an exoskeleton’s degrees of freedomon human gait adaptation.We explored this question using theActive Leg EXoskeleton (ALEX) II. The study presented was performedusing ALEX II under the following two configurations: 1)locking the anterior/posterior translation in the exoskeleton, whileallowing other degrees-of-freedom (labeled as locked mode) and2) keeping the anterior/posterior degree of freedom unlocked (labeledas unlocked mode). Healthy subjects walked at self-selectedspeeds on a treadmill and were trained to walk with a new gait template,scaled down from their normal template. While both groupsshowed adaptation and retention over a 26-min period followingtraining, the unlocked group showed better performance in termsof adaptation and retention compared with the locked group.