A comparative study of surrogate musculoskeletal models using various neural network configurations
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Abstract
Title from PDF of title page, viewed on August 13, 2013Thesis advisor: Reza R. DerakhshaniVitaIncludes bibliographic references (pages 85-88)Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2013The central idea in musculoskeletal modeling is to be able to predict body-level
(e.g. muscle forces) as well as tissue-level information (tissue-level stress, strain, etc.). To
develop computationally efficient techniques to analyze such models, surrogate models
have been introduced which concurrently predict both body-level and tissue-level
information using multi-body and finite-element analysis, respectively. However, this
kind of surrogate model is not an optimum solution as it involves the usage of finite
element models which are computation intensive and involve complex meshing methods
especially during real-time movement simulations. An alternative surrogate modeling
method is the use of artificial neural networks in place of finite-element models. The ultimate objective of this research is to predict tissue-level stresses
experienced by the cartilage and ligaments during movement and achieve concurrent
simulation of muscle force and tissue stress using various surrogate neural network
models, where stresses obtained from finite-element models provide the frame of
reference. Over the last decade, neural networks have been successfully implemented in
several biomechanical modeling applications. Their adaptive ability to learn from
examples, simple implementation techniques, and fast simulation times make neural networks versatile and robust when compared to other techniques. The neural network
models are trained with reaction forces from multi-body models and stresses from finite
element models obtained at the interested elements. Several configurations of static and
dynamic neural networks are modeled, and accuracies close to 93% were achieved, where
the correlation coefficient is the chosen measure of goodness. Using neural networks, the
simulation time was reduced nearly 40,000 times when compared to the finite-element
models. This study also confirms theoretical concepts that special network
configurations--including average committee, stacked generalization, and negative
correlation learning--provide considerably better results when compared to individual
networks themselves.Introduction -- Methods -- Results -- Conclusion -- Future work -- Appendix A. Various linear and non-linear modeling techniques -- Appendix B. Error analysi