Time optimal handling of parts loosely placed at the end-effector (EE) of a robot, known as waiter motion problem, has high practical relevance, which becomes more challenging if the object is a liquid-filled container. The waiter motion problem was often restricted to a time-optimal path following problem, which limits the flexibility and task efficiency. To overcome this restriction, in this paper, the general point to point (PtP) time-optimal motion planning problem is formulated and solved with a multiple shooting method. The formulation includes all relevant dynamic effects (joint friction, contact, motor limits, etc.) assuming rigid behavior of the robot as well as of the object placed at the EE. The trajectory is C2-continuous, avoiding bang–bang behavior of motor torques. The CasADi framework and the Ipopt solver are used for numerical computations. The reported experimental results confirm applicability of the trajectory to real robotic setup in case of rigid objects. Further, handling of containers filled with liquid is addressed. Experiments are compared with numerical results obtained with SPH particle simulation. Experiment and simulation indicate that sloshing effects must be taken into account in the control formulation.

Electrical machine design candidates are typically assessed against several requirements during the development process, including the rotor's mechanical soundness. At present, this is primarily a manual process done by an experienced engineer after the initial electromagnetic design stage. Consequently, there is significant potential to increase the efficiency of the development process and the degree of optimality of the resulting solutions by integrating the mechanical assessment into an automated design optimization workflow. As part of the optimization, the automated process must estimate the mechanical soundness of the current design within a reasonable time and accuracy. To this end, a tailor-made software package combined with a post-processing framework was developed. The software package uses the rotor definition to create and compute a 2D finite element model for the mechanical strain and stress fields. In the post-processing step, a decision is made whether the current geometry should be rejected or further considered in the optimization. Several strategies for such an automated assessment and design decision algorithm are shown and compared in this work.

The optimal design of linear feeding systems, individually tailored to the parts to be processed, is still a considerable challenge in today's industrial automation. Overall objective is to optimize the throughput of correctly sorted and aligned parts, depending on the individual geometries as well as various material and system parameters. However, there is a lack of a detailed understanding of the complex feeding process, the relevant parameters, and their impact on the transport behavior. Therefore, the design of vibrating conveyors today is still mainly based on experience. In this work, we present an approach for the modeling and simulation of such feeding systems with focus on the parts' transport process, and illustrate its potential to support the design phase of vibrating conveyors by an exemplary test case.

Liquid sloshing is a free surface flow phenomenon with particular impact in applications such as dynamics of vehicles, ships or aircrafts (e.g. sloshing in tanks), solutions for vibration damping (e.g. tuned liquid mass dampers), as well as in industrial automation and robotic systems (e.g. handling of liquid-filled vessels). Whether sloshing effects are utilized to reduce vibrations or, on the contrary, introduce disturbing forces to the system, the understanding of the liquid sloshing dynamics is crucial to obtain the respective desired system behavior. To this end, due to the complex dynamic effects, numerical methods are vital means for analysis and optimization. In the present work, we focus on the transport and handling of liquid-filled containers in the context of robotics and automation, analyzed using the method Smoothed Particle Hydrodynamics (SPH). The properties and potential of the chosen numerical approach are investigated and evaluated by examples from literature, and several extensions over conventional SPH implementations are proposed in order to enhance accuracy and robustness.

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.

Increasing quality demands of combustion engines require, amongst others, improvements of the engine's acoustics and all (sub) components mounted to the latter. A significant impact to the audible tonal noise spectrum results from the vibratory motions of fast-rotating turbocharger rotor systems in multiple hydrodynamic bearings such as floating bearing rings. Particularly, the study of self-excited non-linear vibrations of the rotor-bearing systems is crucial for the understanding, prevention or reduction of the noise and, consequently, for a sustainable engine acoustics development. This work presents an efficient modeling approach for the investigation, optimization, and design improvement of complex turbocharger rotors in hydrodynamic journal bearings, including floating bearing rings with circular and non-circular bearing geometries. The capability of tonal non-synchronous vibration prevention using non-circular bearing shapes is demonstrated with dynamic run-up simulations of the presented model. These findings and the performance of our model are compared and validated with results of a classical Laval/Jeffcott rotor-bearing model and a specific turbocharger model found in the literature. It is shown that the presented simulation method yields fast and accurate results and furthermore, that non-circular bearing shapes are an effective measure to reduce or even prevent self-excited tonal noise.

Multi-objective optimization of complex mechatronic systems does not only require detailed simulation models for the individual components, but often demands a multi-physics model that adequately describes their fully coupled behavior. Typically, such a multi-physics model cannot be realized within a single simulation software but rather necessitates the combination of diverse tools. The efficient handling of dependencies among several components in various physical domains within a heterogeneous simulation environment is a key challenge in the context of optimization. The present paper illustrates the multi-objective optimization of a magnetically levitated rotor combining the open-source multibody simulation software HOTINT and the optimization tool MagOpt. MagOpt uses evolutionary algorithms to determine the Pareto-optimum of the multi-physics model, which comprises the flexible multibody system, electromagnetic components and the control system.

In recent years, the development of combustion engines has been dominated by the trend of „downsizing“, i.e. the reduction of quantity and/or volumetric size of the cylinders. In order to increase the specific power of such new engines, while simultaneously reducing their emissions, turbocharging today often realized as multi-stage systems has become indispensable. Over the past decades, the customers’ expectations regarding vibration comfort and engine acoustics have risen significantly. As engine noise has been continuously reduced, the noise emitted by turbocharging systems has recently become a focal point of the engine sound design. One of such noises originating from turbochargers is often referred to as „constant tone“ or „subsynchronous whining“. It originates from self-excited rotor vibrations due to the highly non-linear stiffness characteristics of the journal bearings in modern turbochargers (TC) and can be acoustically perceived in the driver’s cabin. Due to their wide use in practice, the so-called floating ring bearings are here of particular interest. This bearing concept involves a freely rotating journal bearing bushing with separate oil squeeze films between the bushing and both the shaft and the center housing. In the literature, the underlying rotordynamic effect of the constant tone is often called „oil whirl“ [1][4][5][6][7]. The constant tone results from a self-excited vibration in the inner oil film. It may be significant in amplitude (higher than the vibration due to imbalance) and depends on various parameters, such as rotor dimensions, bearing geometry and tribological properties. For most applications, such vibrations can only be restrained, not fully eliminated. The simulative prediction of the constant tone in full floating ring bearings is therefore crucial for the design of turbocharging systems. It is the main focus of the presented research work.

In this paper a fluid-structure interaction problem is investigated, in which fluid flow and flexible deformations of structures are coupled. Exemplarily, the collision of a moving deformable water-filled container with a rigid wall is considered. Two simulation methods are compared to analyze the impact: the Coupled Euler-Lagrange Finite Element Method (CEL) and Smoothed Particle Hydrodynamics Analysis (SPH). On the other hand, the solutions of two software packages are compared, the commercial Finite Element code Abaqus (CEL, SPH) and the open source package HOTINT/ LIGGGHTS (SPH). Goal is to find the various advantages and disadvantages of the two simulation methods and the two software codes.

This work introduces an efficient approach to fluid-structure interaction featuring the coupling of modally reduced multibody system analysis with particle-based fluid mechanics. While the multibody system is computed with respect to a small set of generalized coordinates, the transformation to the full set of actual coordinates is done in the fully parallel framework of the fluid particle simulation. The efficiency of the method is demonstrated and validation is provided along with several numerical examples.

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 applicability of the presented approach to arbitrary geometries and high structural stiffness is studied, as well as an easy model setup. No restriction should be made on the topology of the structure or the complexity of motion.For the fluid part a meshless method, known as smoothed particle hydrodynamics (SPH) is applied, which fulfills the above requirements. While an explicit time integration scheme in SPH provides a fast simulation of the fluid dynamics, advanced methods from flexible multibody dynamics provide a variety of benefits for the simulation of the solid part. Amongst these are specialized structural finite elements for both small and large deformation bodies, joints, stable implicit time-integration schemes, and model reduction techniques.A rule for the interaction between fluids and structures is derived from imposing a distributed potential over boundary segments of the structures, which the fluid particles respond to. The work is concluded by illustrative examples, demonstrating the successful coupling of flexible multibody systems with fluids.

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 is freely available for download, intended for research, education and industrial applications. The main features of the current available version include objects like point mass, rigid bodies, complex point-based joints, classical mechanical joints, flexible (nonlinear) beams, port-blocks for mechatronics applications and many other features such as loads, sensors and graphical objects. HOTINT includes a 3D graphical visualization showing the results immediately during simulation, which helps to reduce modelling errors. In the present paper, we show the current state and the structure of the code. Examples should demonstrate the easiness of use of HOTINT.