Object-oriented modeling, simulation, optimization and visualization of biomechanical systems

In this paper we present a technique for generating the simulation code and the visualization model of a multibody system using a parametrized and extensible object-oriented data model for multibody systems. This object-oriented data model is described in EXPRESS (International Standard Organization 1992b), an object-oriented language in STEP (Standard for the Exchange of Product Model Data) (International Standard Organization 1992a). This approach allows the implementation of this data model in object-oriented database systems, and the exchange of the data model together with the objects (applications, models) between different database systems. This data model is implemented using the integration framework RSYST1 "Reengineering System for Scientific-Technical Software" (Ruhle 1990, Seybold et al. 1996, Seybold 1997a). The module MBSDYM 'Multibody_System to DYMola" generates the DYMOLA "Dynamic Modeling Laboratory" (Elmqvist et al. 1996) input files for the MBS-library (Otter 1995) using an object of the class Multibody_System. ANDECS(2) "Analysis and Design of Controlled Systems" (Grubel 1994) is used to perform multi-objective parameter optimizations of a biomechanical application. This shows the extensibility of the EXPRESS data model and the MBS library for multibody systems to biomechanical systems. The simulation of human motion and the design optimization of parametrized joint moments as well as the parametrized on-line and off-line visualization show the applicability of this approach. A video gives an overview of the high-quality three-dimensional visualization of the simulation and the optimization steps.