An assistive controller for a lower-limb exoskeleton for rehabilitation after stroke, and preliminary assessment thereof

This paper describes a novel controller, intended for use in a lower-limb exoskeleton, to aid gait rehabilitation in patients with hemiparesis after stroke. The controller makes use of gravity compensation, feedforward movement assistance, and reinforcement of isometric joint torques to achieve assistance without dictating the spatiotemporal nature of joint movement. The patient is allowed to self-select walking speed and is able to make trajectory adaptations to maintain balance without interference from the controller. The governing equations and the finite state machine which comprise the system are described herein. The control architecture was implemented in a lower-limb exoskeleton and a preliminary experimental assessment was conducted in which a patient with hemiparesis resulting from stroke walked with assistance from the exoskeleton. The patient exhibited improvements in fast gait speed, step length asymmetry, and stride length in each session, as measured before and after exoskeleton training, presumably as a result of using the exoskeleton.

[1]  D. Mozaffarian,et al.  Heart disease and stroke statistics--2011 update: a report from the American Heart Association. , 2011, Circulation.

[2]  S.K. Agrawal,et al.  Robot assisted gait training with active leg exoskeleton (ALEX) , 2009, 2008 2nd IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics.

[3]  Chitralakshmi K. Balasubramanian,et al.  Relationship between step length asymmetry and walking performance in subjects with chronic hemiparesis. , 2007, Archives of physical medicine and rehabilitation.

[4]  David J. Reinkensmeyer,et al.  Feasibility of Manual Teach-and-Replay and Continuous Impedance Shaping for Robotic Locomotor Training Following Spinal Cord Injury , 2008, IEEE Transactions on Biomedical Engineering.

[5]  D. Reinkensmeyer,et al.  Review of control strategies for robotic movement training after neurologic injury , 2009, Journal of NeuroEngineering and Rehabilitation.

[6]  H. van der Kooij,et al.  Design and Evaluation of the LOPES Exoskeleton Robot for Interactive Gait Rehabilitation , 2007, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[7]  J. Kahn,et al.  Rapid and Long-term Adaptations in Gait Symmetry Following Unilateral Step Training in People With Hemiparesis , 2009, Physical Therapy.

[8]  R. D'Agostino,et al.  The influence of gender and age on disability following ischemic stroke: the Framingham study. , 2003, Journal of stroke and cerebrovascular diseases : the official journal of National Stroke Association.

[9]  Hugo A. Quintero,et al.  A Powered Lower Limb Orthosis for Providing Legged Mobility in Paraplegic Individuals. , 2011, Topics in spinal cord injury rehabilitation.

[10]  Robert Riener,et al.  Generalized elasticities improve patient-cooperative control of rehabilitation robots , 2009, 2009 IEEE International Conference on Rehabilitation Robotics.