Design and Control of the MINDWALKER Exoskeleton

• Published in: IEEE transactions on neural systems and rehabilitation engineering Vol. 23; no. 2; pp. 277 - 286
• Main Authors: Wang, Shiqian, Wang, Letian, Meijneke, Cory, van Asseldonk, Edwin, Hoellinger, Thomas, Cheron, Guy, Ivanenko, Yuri, La Scaleia, Valentina, Sylos-Labini, Francesca, Molinari, Marco, Tamburella, Federica, Pisotta, Iolanda, Thorsteinsson, Freygardur, Ilzkovitz, Michel, Gancet, Jeremi, Nevatia, Yashodhan, Hauffe, Ralf, Zanow, Frank, van der Kooij, Herman
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.03.2015
• Subjects: Actuators; Adult; Balance control; Computer-Aided Design; Equipment Design; Equipment Failure Analysis; exoskeleton; Exoskeleton Device; Exoskeletons; extrapolated center of mass ( XCoM); Feedback; gait assistance; Gait Disorders, Neurologic - physiopathology; Gait Disorders, Neurologic - rehabilitation; Hip; Hip Joint - physiopathology; Humans; Joints; Legged locomotion; Male; Man-Machine Systems; MINDWALKER; Robotics - instrumentation; Robotics - methods; series elastic actuation (SEA); Springs; Therapy, Computer-Assisted - instrumentation; Therapy, Computer-Assisted - methods; Torque; Walking
• ISSN: 1534-4320; 1558-0210; 1558-0210
• DOI: 10.1109/TNSRE.2014.2365697

Powered exoskeletons can empower paraplegics to stand and walk. Actively controlled hip ab/adduction (HAA) is needed for weight shift and for lateral foot placement to support dynamic balance control and to counteract disturbances in the frontal plane. Here, we describe the design, control, and preliminary evaluation of a novel exoskeleton, MINDWALKER. Besides powered hip flexion/extension and knee flexion/extension, it also has powered HAA. Each of the powered joints has a series elastic actuator, which can deliver 100 Nm torque and 1 kW power. A finite-state machine based controller provides gait assistance in both the sagittal and frontal planes. State transitions, such as stepping, can be triggered by the displacement of the Center of Mass (CoM). A novel step-width adaptation algorithm was proposed to stabilize lateral balance. We tested this exoskeleton on both healthy subjects and paraplegics. Experimental results showed that all users could successfully trigger steps by CoM displacement. The step-width adaptation algorithm could actively counteract disturbances, such as pushes. With the current implementations, stable walking without crutches has been achieved for healthy subjects but not yet for SCI paraplegics. More research and development is needed to improve the gait stability.