Formulation of muscle activity identification problem based on shape observation

Abstract

This paper presents a formulation and solution of a problem to identify the muscle activities when a deformation of boundary with respect to an organ are given. An aim of this study is to investigate the mechanism of swallow motion and cause of aspiration. Using a model of tongue consisting of hyper elastic body, we consider that the given deformation is realized by the compulsory displacement on the boundary which shape is known, and that muscle activity is assumed as inelastic principle strain generated in the direction of minimum principle strain of the hyper elastic deformation. The identification problem of muscle activities is formulated using the inelastic principle strain as design variable and the work done by the compulsory displacement as cost function of minimization. Solution of the problem is presented based on the scheme using the H¹ gradient method for topology optimization problem of density type. A numerical example done in the previous study is introduced to show the validity of the present theory.