Mathematical Simulation of Dynamics for Exoskeleton Including Variable-Length Links with Adjustable Stiffness

A method of composing exoskeleton dynamics equations is presented in this paper. The exoskeleton is simulated with a system of rigid bodies including variable-length links with adjustable stiffness. The dependence of the force of resistance of the magnetic-rheological medium to the movement of the piston is obtained depending on the applied external magnetic field. The article sequentially considers models of one link of variable length with adjustable stiffness, two links and three links. For each model, a system of differential equations of motion is compiled. Then, based on the analysis of the structure of the obtained systems of differential equations of motion, a generalization is carried out for the case of a model consisting of an arbitrary finite number of links. The system dynamics is described by differential equations in generalized vector–matrix form. The damping forces, required for motion stabilization, are provided by magneto-rheological fluid controlled by magnetic field strength. The developed model of an exoskeleton with links of variable length with adjustable stiffness can be used in the creation of a human–machine mechatronic system as an auxiliary or main means for moving and performing various physical loads in order to reduce them on the human musculoskeletal system. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.