3D refined model of exoskeleton link with adjustable stiffness and actuator capabilities and accuracy estimation of its performance in comparison with the previously created models

Abstract

A fairly detailed exoskeleton variable-length link model with adjustable stiffness is considered in the article. The refinement of the previously created models in terms of discretization is made. The geometrical dimensions of the top and bottom rods, the cylinder, the cylinder covers, the piston that moves inside the cylinder with magneto-rheological fluid, as well as their masses and moments of inertia relative to coordinate axes are refined. The payload mass at the end of the link, resulting under the effect of other links or the attached actuator, is simulated by a homogeneous ball. The change of the mass in the bottom and top parts of the cylinder, and the change of the moment of inertia of the link as the magneto-rheological fluid flows inside the cylinder from one part to another through the piston with micro-channels are made more precise. All these made it possible to bring the model closer to the real technical device. The mathematical model of a more accurate link model is compiled. The possible model of actuator, functioning based on the proposed refined model of the exoskeleton link with magneto-rheological fluid, is described. The possibility of its functioning and the options to control it are studied. The accuracy estimation for the refined model in comparison to the previously created models is made. All the results presented were obtained in a program created in the universal software environment "Wolfram Mathematica". The links of the proposed model can be used in designing next-generation exoskeletons, which are more comfortable comparing to the existing models