A Modular and Efficient Approach to Computational Modeling and Sensitivity Analysis of Robot and Human Motion Dynamics

In this paper a new class library for the computation of the forward multi-body-system (MBS) dynamics of robots and biomechanical models of human motion is presented. By the developed modular modeling approach the library can be flexibly extended by specific modeling elements like joints with specific geometry or different muscle models and thus can be applied efficiently for a number of dynamic simulation and optimization problems. The library not only provides several methods for solving the forward dynamics problem (like articulated body or composite rigid body algorithms) which can transparently be exchanged. Moreover, the numerical solution of optimal control problems, like in the forward dynamics optimization of human motion, is significantly facilitated by the computation of the sensitivity matrix with respect to the control variables. Examples are given to demonstrate the efficiency of the approach. In this paper MBSlib, an object-oriented library for the efficient calculation of the forward dynamics of multi-body systems (MBS) written in C++ is presented. Following the discussion of the applied modeling methodology the provided methods for the calculation of MBS forward dynamics and sensitivities is presented. The paper closes with application examples.