Aspects of efficient and reliable multibody system simulation

Multibody system equations can be generated in various forms. All of these may be interpreted as results of two basic approaches, the augmentation- and the elimination-method. The former method yields the descriptor form of the system motion, a set of differential-algebraic equations (DAE), and the latter the state space representation, a minimal set of ordinary differential equations (ODE). Both of these methods are surveyed. Particular emphasis is on the discussion of recursive computational schemes, generating the equations of motion with a number of operations, which is proportional to the number N of system bodies (O(N)-formulations). For simulation purposes one would like to create that set of system equations, which can be generated most efficiently and for which the most efficient and reliable solution techniques are available. Numerical solution techniques for ODE have been studied in great detail and they are well-developed. By contrast, DAE have not been investigated for such a long time. In view of new developments in the latter field the generation of all the equations required for an efficient and reliable solution of DAE describing multibody system motion is discussed. These methods, i.e., an O(N)-formulation and new techniques for solving DAE, are implemented in the SIMPACK code. Its capabilities are illustrated by simulation of multibody robot models

Effiziente Simulation der Dynamik mechatronischer Systeme für industrielle Anwendungen

Das vorliegende Dokument dient als Dokumentation einiger theoretischer Grundlagen und Design-Ideen des Mehrkörper-Simulationsprogramms SIMPACK (Version 7.9), die auch heute noch gültig sind. Insbesondere wird die Integration der MKS-Simulation in den CAE-Entwicklungsprozeß und die daraus entstehenden Problematiken an die numerischen Methoden sowie die Rückwirkung auf die MKS-Formalismen behandelt. Es erfolgt eine detailierte Beschreibung von theoretischen und softwaretechnischen Entwicklungen auf den unterschiedlichen Ebenen des gesamten Berechnungsprozesses und eine Bewertung in Bezug auf ihre Effizienzsteigerung

DETC2003/VIB-48348 FROM OFF-LINE TO REAL TIME SIMULATIONS BY MODEL REDUCTION AND MODULAR VEHICLE MODELLING 1

ABSTRACT Over the last couple of years there has been a growing tendency in the automotive industry to use more active control systems with mechatronic components, realized by electronic control units (ECU). As the ECU is a highly complex system and also for reasons of safety and costs the ECU-test is not carried out in road tests, but at a much earlier time, i.e. in the laboratory, using Hardware-in-the-Loop (HiL) simulation. This requires real-time environmental models. This paper shows how the transition from offline multi-body-system (MBS) models to real-time simulation can be achieved automatically by using a component oriented reduction procedure for vehicle suspensions, which keeps the full component parameterization. This necessitates a transformation of the equations of motion from differential algebraic equations (DAE) into ordinary differential equations (ODE). For use in HiL-simulators the equations of motion with open interfaces of the applied forces and torques are provided to be integrated in a modular dynamic ride model. MOTIVATION Numerical simulation of system dynamics is today a standard in the design of cars and trucks. The multibody system (MBS) analysis is applied to suspension kinematics and compliant kinematics, handling performance and ride comfort as well as the generation of load data for life time prediction. Additionally to these off-line simulation tasks the MBS method is established in the real-time simulation domain, typically for the design of vehicle control systems and the test of electronic control units

Simulation of Mechatronic Vehicles with SIMPACK

Oberpfaffenhofen 970814

Real-Time Simulation of Flexible Space Manipulator Dynamics

Accurate dynamic models for space manipulator systems are required for supporting both the design and the development of the system itself, and furthermore, for incorporating real-time models within an operational environment be it on ground or in space. This paper treats the whole ptoblem area encountered in both, non-real-time and real-time modelling and simulation of multibody systems with the specific emphasis on space robotics. The most important topics are covered that start from the development of a mathematical model derived from the real-world system, and extend to the special features in finding the adequate multibody formalism, the appro- priate numerical integration method, and finally some specific computer hardware features. Simulation results are presented for European robotized space applications like the European Robotic Arm (ERA), and the Experimental Servicing Satellite (ESS) coupled via a manipulator system to a non-cooperative target

Comparison of Two Approaches to Incorporate Geometric Stiffness Terms in Flexible Multibody Dynamics

Two approaches for the development of the equations of flexible body motions subject to large overall motions and forces are presented and their properties are compared. The required geometric stiffening terms are derived using the virtual power principle. Their influence is studied for a rotating slender beam

SIMPACK as a Tool for Automotive Engineering

SIMPACK a leading multibody-system (MBS) analysis software for general mechanical systems has envolved into a multidisciplinary simulation package for the analysis and integrated design of mechatronic systems. Being generally recoginized for its very efficient solvers and advanced bidirectional interfaces to other CAE tools, SIMPACK has recently introduced the Automotive+ module to provide a toolbox for the special needs of advanced automotive engineers. This paper gives a brief overview of SIMPACK with a special focus on its features for the automotive industry