15 Fakultätsübergreifend / Sonstige Einrichtung

Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/16

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1992 - 199912010 - 20151

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Institute: search.filters.UBSInstitut.Fakultätsübergreifend / Sonstige EinrichtungAuthor: search.filters.author.Günther, Michael

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    Comparative sensitivity analysis of muscle activation dynamics
    (2015) Rockenfeller, Robert; Günther, Michael; Schmitt, Syn; Götz, Thomas
    We mathematically compared two models of mammalian striated muscle activation dynamics proposed by Hatze and Zajac. Both models are representative for a broad variety of biomechanical models formulated as ordinary differential equations (ODEs). These models incorporate parameters that directly represent known physiological properties. Other parameters have been introduced to reproduce empirical observations. We used sensitivity analysis to investigate the influence of model parameters on the ODE solutions. In addition, we expanded an existing approach to treating initial conditions as parameters and to calculating second- order sensitivities. Furthermore, we used a global sensitivity analysis approach to include finite ranges of parameter values. Hence, a theoretician striving for model reduction could use the method for identifying particularly low sensitivities to detect superfluous parameters. An experimenter could use it for identifying particularly high sensitivities to improve parameter estimation. Hatze’s nonlinear model incorporates some parameters to which activation dynamics is clearly more sensitive than to any parameter in Zajac’s linear model. Other than Zajac’s model, Hatze’s model can, however, reproduce measured shifts in optimal muscle length with varied muscle activity. Accordingly we extracted a specific parameter set for Hatze’s model that combines best with a particular muscle force-length relation.
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    Interactive control of biomechanical animation : contribution to the GI Workshop: Visualisierung - Rolle von Interaktivitat und Echtzeit, GMD, Sankt Augustin, 2.-3. Juni 1992
    (1992) Ertl, Thomas; Ruder, Hanns; Gruber, Karin; Günther, Michael; Hospach, Frank; Krebs, Thomas; Subke, Jörg; Widmayer, Karin
    Physical based animation can be generated by performing a complete dynamical simulation of multi-body systems. This leads to a complex system of differential equations which has to be solved incorporating biomechanical results for the physics of impacts. Motion control is achieved by interactively modifying the internal torques. Realtime response requires the distribution of the workload of the computation between a highspeed computerserver and the graphics workstation by means of a remote procedure call mechanism.