Resumen
This study presents a new method to estimate the residual forces (tones) of the trunk muscles at rest, including the deep ones that are difficult to reach with nonintrusive means. Compared to classical methods (intrusive means), this method is painless and safe for the subject, as it uses only trunk experimental stiffness in conjunction with numerical modeling. The present method can be used independently or to supplement classical means which provide direct measures for the tone of superficial muscles. With these measures the identification problem is reduced to finding the tones of only the deep muscles. The proposed method can then be applied, for the specific subject with further gain in accuracy and efficiency. The accuracy of results can be improved by considering more muscle classes in the identification methodology.