Dynamics of two-link exoskeleton support leg, considering payload and adjustable stiffness

The exoskeleton comfortability issues are not solved at present, which prevents their widespread application. The study suggests a method of resolving these issues based on the variable-length links with adjustable stiffness. The paper describes the 3-D model of exoskeleton supporting leg consisting of two variable-length links with adjustable stiffness. The payload is simulated with a point mass located at the end of the second link. The link length control is implemented by adjusting the stiffness of magneto-rheological fluid in the links. The fluid stiffness depends on the applied magnetic field strength. The pivoting points are simulated with spherical hinges. The system dynamics is described by the Lagrange equations using the angles between neighbouring links and the coordinate corresponding to the link length. Inverse dynamics problem solution methods for systems with constraints stabilization are used for obtaining control torques and lengthwise forces. The animation of mechanism motion demonstrates the adequacy of the proposed simulation procedure. The proposed model can contribute to development of more comfortable exoskeletons that are simulating biomechanics of human musculoskeletal system more precisely. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.