# Johannes GerstmayrUniversity of Innsbruck | UIBK · Institute of Mechatronics

Johannes Gerstmayr

Univ.-Prof. DI Dr. techn.

## About

173

Publications

22,916

Reads

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2,282

Citations

Introduction

Research interests:
flexible multibody system dynamics; slender structures; realistic modeling of robots and machines; modular and mobile robots; numerical simulation of (highly nonlinear) dynamic systems;
Flexible multibody dynamics code EXUDYN in C++ with Python integration: https://github.com/jgerstmayr/EXUDYN

Additional affiliations

November 2014 - September 2020

September 2007 - October 2014

September 2004 - August 2007

**various institutions**

Position

- APART Scholarship

Description

- Johannes Kepler University Linz, Austria; University of Illinois at Chicago, US; Instituto Superior Tecnico, Portugal; University Duisburg-Essen, Germany

Education

October 1992 - November 1997

## Publications

Publications (173)

This paper presents the approach of the RoboCup@Work team tyrolics of the university of Innsbruck to design, develop and build a mobile manipulator with 10 degrees of freedom. The mobile manipu-lator LeoBot uses Mecanum wheels to enable omnidirectional movement and includes a Franka Emika Panda serial manipulator. This paper fo-cuses on hardware de...

Mithilfe sogenannter Mecanumräder kann ein omnidirektionaler Antrieb realisiert werden. Diese oftmals in Robotersyste-
men und fahrerlosen Transportsystemen eingesetzten Räder ermöglichen es Fahrzeugen sowohl eine ebene translatorische
Bewegung als auch eine Drehung um die Hochachse auszuführen. Dies ermöglicht beliebige Trajektorien und eine freie...

The accuracy of a multibody model to predict the behavior of a real physical system depends heavily on the correct choice of model parameters. Identifying unknown system parameters that cannot be computed or measured directly is usually time-consuming and costly. If measurement data is available for the physical system, the parameters in the corres...

The present work addresses pipes conveying fluid and axially moving beams undergoing large deformations. A novel two dimensional beam finite element is presented, based on the Absolute Nodal Coordinate Formulation (ANCF) with an extra Eulerian coordinate to describe axial motion. The resulting formulation is well known as Arbitrary Lagrangian Euler...

Three rotation parameters are commonly used in multibody dynamics or in spacecraft attitude determination to represent large spatial rotations. It is well known, however, that the direct time integration of kinematic equations with three rotation parameters is not possible in singular points. In standard formulations based on three rotation paramet...

The present paper investigates the static equilibrium of a thin elastic structure with concave sidecut pressed against a flat rigid surface, as an idealization of a ski or snowboard undergoing the conditions of a carved turn. An analytical model is derived to represent the contact behaviour and provide an explanation for concentrated loads occurrin...

In this paper, we present a reconfiguration algorithm for shape-shifting modular robots with a triangular structure. The algorithm is derived from a novel description of the configuration space based on extended binary trees. Extended binary trees representing the same configuration are grouped into equivalence classes, which allows for a one-to-on...

The ability of a multibody dynamics model to accurately predict the behavior of a real system depends heavily on the correct choice of model parameters. The identification of unknown system parameters, which cannot be directly computed or measured is usually time consuming and costly. If experimental measurement data of the real system is available...

Mobile robots and autonomous guided vehicles have become an indispensable part of modern industrial environments and are used for a wide range of handling operations. To fully use the potential of mobile platforms, omnidirectional platforms are a good choice. A prominent and widely used variant in the industry are Mecanum wheels, which allow arbitr...

The present paper addresses axially moving beams with co-moving concentrated masses while undergoing large deformations. For the numerical modeling, a novel beam finite element is introduced, which is based on the absolute nodal coordinate formulation extended with an additional Eulerian coordinate to represent the axial motion. The resulting formu...

The goal of the present paper is to investigate inertial measurement systems for the ability to reconstruct the short time rigid body motion of objects, e.g. clumps in snow avalanches. While strapdown inertial navigation is well established, special algorithms are needed for the accurate motion reconstruction for short time motion with partially kn...

Team Description Paper for the mobile manipulator Leobot, build by the RoboCup@work team Tyrolics from the Univercity of Innsbruck

We consider the trajectory tracking optimization for an elastic joint robot with noisy joint-velocity readings and actuation torque limits. We propose an approach targeting the minimization of the trajectory tracking error, of the velocity noise amplification on the control commands, and of the trajectory execution time. We integrate the use of a f...

In a recent paper of the authors, a novel nodal-based floating frame of reference formulation (FFRF) for solid finite elements has been proposed. The nodal-based approach bypasses the unhandy inertia shape integrals ab initio, i.e. they neither arise in the derivation nor in the final equations of motion, leading to a surprisingly simple derivation...

Flexible multibody dynamics systems based on 3D continuum finite elements are important for industrial research but usually require time consuming implementations in research codes. The conventional continuum-mechanics-based floating frame of reference formulation (FFRF) is usually employed for these applications. However, the conventional approach...

Rigid bodies are an essential part of multibody systems. As there are six degrees of freedom in rigid bodies, it is natural but also precarious to use three parameters for the displacement and three parameters for the rotation parameters - since there is no singularity-free description of spatial rotations based on three rotation parameters. Standa...

Programmable structures are formed by autonomous and adaptive triangular cells. However, they are composed of a large number of parts, specifically bearings, which make them laborious to manufacture and expensive. An essential part of these programmable structures are six-bar linkages, which allow to build cells that can preserve the underlying geo...

The conventional continuum-mechanics-based floating frame of reference formulation involves unhandy so-called inertia-shape-integrals in the equations of motion, which is why, commercial multibody software codes resort to a lumped mass approximation to avoid the evaluation of these integrals in their computer implementations. This paper recaps the...

The Floating Frame of Reference Formulation (FFRF) is one of the most widely used methods to analyze flexible multibody systems subjected to large rigid-body motion but small strains and deformations. The FFRF is conventionally derived via a continuum mechanics approach. This tedious and circuitous approach, which still attracts attention among res...

EXUDYN is a C++ based Python library for efficient simulation of flexible multibody dynamics systems.
It is designed to easily set up complex multibody models, consisting of rigid and flexible bodies with joints, loads and other components. It shall enable automized model setup and parameter variations, which are often necessary for system design b...

Motivated by an application example, the comfort zone for mobile kinematically redundant manipulators is defined. The position and orientation of the mobile platform (=base of the manipulator) and the joint angles are selected in such a way that selected target functions are minimized. These objective functions are derived from known measures such...

A novel formulation for the description of spatial rigid body motion using six non-redundant, homogeneous local velocity coordinates is presented. In contrast to common practice, the formulation proposed here does not distinguish between a translational and rotational motion in the sense that only translational velocity coordinates are used to desc...

This paper presents a novel system‐level model order reduction scheme for flexible multibody simulation, namely the system‐level affine projection (SLAP). Contrary to existing system‐level model order reduction approaches for multibody systems simulation, this methodology allows to obtain a constant reduced order basis which can be obtained in a no...

In this paper, we present a formulation for the dynamic analysis of multibody systems using non‐redundant unified local velocity coordinates. The motivation for the present work is the result of an earlier investigation of unified local velocity coordinates of Holzinger et al. [1]. The equations of motion presented by the authors allow the descript...

The trend away from physical towards virtual prototyping as well as increasing industrial demands require advanced simulation tools for dynamical systems. Virtually all engineering systems are assemblies and are associated with stresses, noise and vibrations; therefore, flexible multibody simulations are inevitable for accurate predictions. However...

Zusammenfassung
Für die auditive und visuelle Wahrnehmung bieten sogenannte „Virtual Reality“-Systeme eine hochauflösende Nachbildung der Wirklichkeit bei gleichzeitig niedrigen Kosten. Um digitalisierte Objekte noch näher an die Realität zu bringen, werden in dieser Arbeit programmierbare Strukturen vorgestellt, welche neben der visuellen auch die...

Rigid body models are only sufficient for rough estimates of the dynamics of real world systems, such as machines, robots and vehicles. Although, deformations are usually small compared to a rigid body motion, they need to be taken into account in many cases; e.g., to determine vibrations, resonance effects and stresses. So far, there are two main...

The purpose of this study was to define a method for the validation of a numerical model representing a snowboard structure undergoing the conditions of a carved turn. A static load bench was developed to expose a snowboard to in-situ conditions. The deformed shape of the structure was measured with the use of retro-reflective markers, whose positi...

An increasing focus on the optimization of products to higher levels of reliability and efficiency in combination with the growing complexity of our technology dominated world pushes industry away from physical towards virtual prototyping. Which is why, advanced engineering simulation tools have become indispensable to master today's challenges.
T...

The reduction in the number of coordinates for flexible multibody systems is necessary in order to achieve acceptable simulation times of real-life structures and machines. The conventional model order reduction technique for flexible multibody systems is based on the floating frame of reference formulation (FFRF), using a rigid body frame and supe...

The use of multibody simulation tools allows complex machinery to be described in detail while still providing a solution for the system in real time. As mechanical components are often accompanied by other dynamical systems, such as hydraulics, description of each subsystem is required to fully describe the dynamics of complex machinery. A potenti...

Increasing industrial demands on reliability and efficiency require advanced simulation models of dynamical systems. Virtually all engineering systems are assemblies made out of multiple components which interact with each other during operation. The forces required to execute desired motions are associated with stresses, noise and vibrations, whic...

Increasing industrial demands require advanced simulation models of dynamical systems. Virtually all engineering systems are assemblies and associated with stresses, noise and vibrations. Hence, flexible multibody simulations are inevitable for accurate predictions. Most real-world FE models contain numerous DOFs that cannot be handled without mode...

A new approach for the transient simulation of idealized ropeway systems is proposed. Therefore, common numerical tools known from flexible multibody dynamics are adapted. The running cable is modelled by means of flexible beam elements in an arbitrary Lagrangian-Eulerian manner. That is, the deformational motion of the cable corresponds to the mot...

A new approach for the transient simulation of idealized ropeway systems is proposed. Therefore, common numerical tools known from flexible multibody dynamics are adapted. The running cable is modelled by means of flexible beam elements in an arbitrary Lagrangian-Eulerian manner. That is, the deformational motion of the cable corresponds to the mot...

The aim of the present paper is to evaluate six particular beam finite elements based on the absolute nodal coordinate formulation (ANCF). Specifically, accuracy, computational efficiency and numerical stability are compared for those beam finite elements. The finite elements under consideration are planar as well as spatial beams, which are formul...

Light-weight structures and high-performance mechanical
systems lead to an increasing amount of vibrations. In order to
comply with standards in noise and vibration limits, the simula-
tion of flexible multibody systems is inevitable. Due to the size
of the finite element models of real-life mechanical systems, a
model order reduction is necessary...

In industrial practice, the floating frame of reference formulation (FFRF)-often combined with the component mode synthesis (CMS) in order to reduce the number of flexible degrees-of-freedom-is the common approach to describe arbitrarily shaped bodies in flexible multibody systems. Owed to the relative formulation of the flexible deformation with r...

The key idea of the absolute nodal coordinate formulation (ANCF) is to use slope vectors in order to describe the orientation of the cross-section of structural mechanics components, such as beams, plates or shells. This formulation relaxes the kinematical assumptions of Bernoulli–Euler and Timoshenko beam theories and enables a deformation of the...

As the need to model flexibility arose in multibody dynamics, the floating frame of reference formulation was developed, but this approach can yield inaccurate results when elastic displacements becomes large. While the use of three-dimensional finite element formulations overcomes this problem, the associated computational cost is overwhelming. Co...

The paper is concerned with the modeling of the planar motion of a horizontal sheet of metal in a rolling mill. Inhomogeneous velocity profiles, with which the material is generated at one roll stand and enters the next one, lead to the time evolution of the deformation of the metal strip. We propose a novel kinematic description in which the axial...

Modeling the interaction of fluids with moving, flexible structures is a major and still very challenging subject in the field of multi-physics problems. In this work, an efficient computational approach based on the coupling of modally reduced flexible multibody systems with fluids modeled by means of smoothed particle hydrodynamics is outlined.

An established postprocessing procedure for the determination of interlaminar shear and normal stresses based on the results of a conventional shell finite element analysis is generalized for arbitrarily curved laminated shells. The method relies on the three-dimensional equilibrium conditions and an extended lamination theory. Underlying approxima...

Optimizing mechatronic components is of increasing importance, e.g. for minimizing energy consumption and the use of rare materials. MagOpt is a modular software tool for the simulation and optimization of mechatronic components. Parametric design optimization can be carried out with various different optimization strategies like gradient-based met...

The aim of this paper is to highlight and identify the in°uencing parameters of the nonlinear
behavior of highly deformable structures. Therefore, as an example, a large deformable square
frame consisting of four slender members of equal length has been investigated experimentally.
Based on highly resolving measurements using the digital image corr...

Due to the increase in speed and lightweight construction, modern robots vibrate significantly during motion. Thus, accurate mechanical modeling and detailed controller behavior is essential for accurate path planning and control design of robots. For the suppression of undesired vibrations detailed models are used to develop robust controllers. Le...

An extension of Reissner’s geometrically exact theory for the plane deformation of beams allows a consistent constitutive modeling of various types of material behavior. In the present paper, such formulation is used to describe the coupled response of slender piezoelectric structures. Starting from the local equilibrium relations and the geometric...

In this paper the influencing factors of the nonlinear behavior of a highly deformable square frame are aimed to highlight and identify. Therefore, in a first step a square frame consisting of four slender members of equal length has been investigated experimentally. Subsequently to these investigations, a numerical model is set up with a beam fini...

Simulations of the behaviour of complex mechatronic systems require optimal simulation parameters for obtaining realistic results. For highly accurate mechatronic simulations, an algorithm for searching the optimal parameters is required. In the field of robotics the identification based on minimization of the residuum with least square methods is...

To suppress vibration and noise of mechanical structures piezoelectric ceramics play an increasing role as effective, simple and light-weighted damping devices as they are suitable for sensing and actuating. Out of the various piezoelectric damping methods this paper compares mode based active control strategies to passive shunt damping for thin pl...

In the scope of this paper, a finite-element formulation for an axially moving beam is presented. The beam element is based on the absolute nodal coordinate formulation, where position and slope vectors are used as degrees of freedom instead of rotational parameters. The equations of motion for an axially moving beam are derived from generalized La...

The multibody dynamics and finite element simulation code has been developed since 1997. In the past years, more than 10 researchers have contributed to certain parts of HOTINT, such as solver, graphical user interface, element library, joint library, finite element functionality and port blocks. Currently, a script-language based version of HOTINT...

In industrial practice, the floating frame of reference formulation (FFRF)—often combined with the component mode synthesis (CMS) in order to reduce the number of flexible degrees-of-freedom—is the common approach to describe arbitrarily shaped bodies in flexible multibody systems. Owed to the relative formulation of the flexible deformation with r...

In this paper, the accuracy of the geometrically exact beam formulation and absolute nodal coordinate formulation are studied by comparing their predictions against experimental data referred to as the “Princeton beam experiment.” The experiment deals with a cantilevered beam experiencing coupled flap, lag, and twist deformations. In the absolute n...

Many conventional time integration schemes frequently adopted in flexible multibody dynamics fail to retain the fundamental conservation laws of energy and momentum of the continuous time domain. Lack of conservation, however, in particular of angular momentum, may give rise to unexpected, unphysical results. To avoid such problems, a scheme for th...

For the modeling of large deformations in multibody dynamics problems, the absolute nodal coordinate formulation (ANCF) is advantageous since in general, the ANCF leads to a constant mass matrix. The proposed ANCF beam finite elements in this approach use the transverse slope vectors for the parameterization of the orientation of the cross section...

A three-dimensional nonlinear finite element for thin beams is proposed within the absolute nodal coordinate formulation (ANCF). The deformation of the element is described by means of displacement vector, axial slope and axial rotation parameter per node. The element is based on the Bernoulli-Euler theory and can undergo coupled axial extension, b...

The aim of this study is to provide a comprehensive review of the finite element absolute nodal coordinate formulation, which can be used to obtain efficient solutions to large deformation problems of constrained multibody systems. In particular, important features of different types of beam and plate elements that have been proposed since 1996 are...

The present work deals with a computational approach to fluid-structure interaction (FSI) problems by coupling of flexible multibody system dynamics and fluid dynamics. Since the methods for the numerical modeling are well known, both for the structural and the fluid part, the focus of this work lies on the coupling formalism. Moreover, the applica...

In the present paper, a three-dimensional shear deformable beam finite element is presented, which is based on the absolute nodal coordinate formulation (ANCF). The orientation of the beam's cross section is parameterized by means of slope vectors. Both a structural mechanics based formulation of the elastic forces based on Reissner's nonlinear rod...

The absolute nodal coordinate formulation (ANCF) has been developed for the modeling of large deformation beams in two or three dimensions. The absence of rotational degrees of freedom is the main conceptual difference between the ANCF and classical nonlinear beam finite elements that can be found in literature. In the present approach, an ANCF bea...

A standard technique to reduce the system size of flexible multibody systems is the component mode synthesis. Selected mode shapes are used to approximate the flexible deformation of each single body numerically. Conventionally, the (small) flexible deformation is added relatively to a body-local reference frame which results in the floating frame...

The volume contains 19 contributions by international experts in the field of multibody system dynamics, robotics and control. The book aims to bridge the gap between the modeling of mechanical systems by means of multibody dynamics formulations and robotics. In the classical approach, a multibody dynamics model contains a very high level of detail...

The absolute nodal coordinate formulation (ANCF) has been developed for the modeling
of large deformations in multibody dynamics problems. In contrast to classical nonlinear
beam finite elements in literature, the ANCF does not use rotational degrees of freedom and
therefore does not necessarily suffer from singularities emerging from angular param...

In many applications, nonlinear beams undergoing bending, axial and shear deformation are important structural elements. In the present paper, a shear deformable beam finite element is presented for such applications. Since displacements and displacement gradients are chosen as the nodal degrees of freedom, an equivalent displacement and rotation i...