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This study is focused on the application of 3D-printed elements and conventional elements to create a prototype of a custom-made exoskeleton for lower limb rehabilitation. The 3D-printed elements were produced by using Fused Deposition Modeling technology and acrylonitrile butadiene styrene (ABS) material. The scope of this work involved the design and construction of an exoskeleton, experimental testing of the ABS material and numerical research by using the finite element method. On the basis of the obtained results, it was possible to deduce whether the load-bearing 3D-printed elements can be used in the proposed mechanical construction. The work contains full data of the material models used in FEM modeling, taking into account the orthotropic properties of the ABS material. Various types of finite elements were used in the presented FE models. The work is a comprehensive combination of material testing issues with the possibility of implementing the obtained results in numerical strength models of machine parts. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate new fusiform muscle models. Each of these models treats a muscle as a system composed of parts characterized by different mechanical properties. These models explain the influence of differences in the stiffness of lateral parts and the degree of muscle model discretization. Each muscle model is described by a system of differential equations and a single integro-differential equation. Responses of fifty-four muscle model forms are examined using a complex exertion composed of three types: eccentric-concentric exertion, isokinetic-isometric exertion and step exertion. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present the computational model of skeletal muscle, which was treated as the structure of different mechanical properties. The method of identification of those properties is described in detail. In addition, the method of quantitative and qualitative verification of this model is proposed. Applying this computational model, the forces of real muscles can be evaluated without using any optimization technique. Such an approach will be described in the part II of the paper. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to create and analyze a Pareto-optimal problem that would describe cooperation between mono- and bi-articulate lower limb muscles in sagittal plane., Methods: Equations describing the problem were derived and analyzed, additional constrains were introduced and experimental verification based on gait video analysis was performed., Results: Uncertainty of Pareto-optimal solution is shown for the muscular-skeletal system. An explanation of this situation is presented and discussed. Moreover, this theoretical observation is compared with a lack of gait reproducibility. Small but noticeable differences in gait cycles are shown and explained., Conclusions: A muscular system redundancy is shown and explained by the meaning of Pareto problem. Theoretical considerations were confirmed through a gait analysis. This leads to the conclusion, that during muscle cooperation each movement cycle can be different from the previous one, however due to physiological restrictions only a narrow equivalence class of the possible solutions exists.