Structural Identifiability Analysis and Preliminary Parameter Estimation for an Arm Model Incorporating the Hill Muscle Model

In this paper we describe a structural identifiability analysis of a musculoskeletal model intended for exploring movement control using FES. The force actuators in the model are Hill type musculo-tendon models. Structural identifiability analysis was carried out on the standard Hill model and the results showed that parameters in the Hill model cannot be uniquely determined and therefore the model was not globally identified. However, an analysis of a commonly used modified form of the Hill model, in which all the components are in parallel, gives a model that is globally identifiable. Parameter estimation showed good agreement with measured data but also identified limitations. By considering the musculo skeletal model as a system of systems, the overall model can be considered globally identifiable.