Complex joint musculoskeletal system of the lower limb described in a generalized coordinate system : CAD optimized description of human body movement

Abstract

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The goal of this work was to realize a complex joint musculoskeletal system of the lower limb which brings great advantages in terms of time reduction due to the inverse dynamic optimization.<br />Furthermore, the possibility of including contact forces and ligament forces into the optimization had to be realized. A generalized coordinate system, named natural coordinate system, created by Garcia de Jalon was used and adapted for the biomechanical needs. To realize the MATLAB routines based on the work of R. Dumas and L. Chèze it was necessary to adapt existing formulae to these specific needs. This work tries to give an overview of how this mechanical description works, why people should consider using them, and which advantages and disadvantages will be confronted by using natural coordinates.<br />Furthermore the application of this mechanical description on the model used will be explained. The question of how to include or exclude individual ligament and contact forces will be answered. An additional benefit can be considered with the application of a pseudoinverse calculation of the inverse dynamic system. This shows an additional significant reduction of the calculation effort and can be applied for every inverse dynamic analysis and especially in the field of biomechanics.