Virtual Vehicle Competence Center

Vehicle, Austria

Virtual Vehicle Competence Center

Vehicle, Austria
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Schwarzl C.,Virtual Vehicle Competence Center | Peischl B.,University of Graz
Proceedings - International Conference on Quality Software | Year: 2010

Today's multimedia solutions in the automotive industry are complex and distributed hardware/software systems that interact with a multitude of different environments. Assuring the functional correctness of such software-enabled systems is a major issue to maintain and improve overall product quality. In this article we report on a test case generation approach, that allows engineers to employ well-known UML state chart models to deduce test cases fully automatically. Our approach is based on symbolic transition systems (STSs) and overcomes the intricacies resulting from straightforward application of enumerative test models (e.g. state space explosion). The derivation of the test sequences is performed by searching paths through the STS models with respect to their communication structure. By calculating the weakest preconditions of these paths the validity of the paths (and their related parameters) is ensured. Notably, our first empirical results on an industry showcase - a flashing indicator model developed with our industry partner - indicate that our model composition approach is applicable for both - systematic as well as randomized test case generation. © 2010 IEEE.

Benedikt M.,Virtual Vehicle Competence Center | Benedikt M.,University of Graz | Stippel H.,Virtual Vehicle Competence Center | Watzenig D.,Virtual Vehicle Competence Center
SAE Technical Papers | Year: 2010

In the automotive industry well-established different simulation tools targeting different needs are used to mirror the physical behavior of domain specific components. To estimate the overall system behavior coupling of these components is necessary. As systems become more complex, simulation time increases rapidly by using traditional coupling approaches. Reducing simulation time by still maintaining accuracy is a challenging task. Thus, a coupling methodology for co-simulation using adaptive macro step size control is proposed. Convergence considerations of the used algorithms and scheduling of domain specific components are also addressed. Finally, the proposed adaptive coupling methodology is examined by means of a cross-domain co-simulation example describing a hybrid electric vehicle. Considerable advantages in terms of simulation time reduction are presented and the trade-off between simulation time and accuracy is depicted. Copyright © 2010 SAE International.

Zangl H.,University of Graz | Fuchs A.,Virtual Vehicle Competence Center | Bretterklieber T.,University of Graz | Moser M.J.,University of Graz | Holler G.,University of Graz
IEEE Transactions on Instrumentation and Measurement | Year: 2010

Passive or semiactive wireless sensors, i.e., sensors that require neither wires nor external power supply/batteries, are attractive for many measurement problems. Standard approaches based on Radio Frequency Identification technology usually have difficulties when a fairly conductive matter such as steel or a large amount of water is in the vicinity of the devices. This paper investigates methods for power and data transmission, even through the metal walls, e.g., of a tank or a pipe using super low frequency carrier signals. The feasibility is demonstrated by means of finite-element analysis and laboratory experiments and validated with a prototype setup for both a steel pipe and a tin container. Experimental results for capacitive fill-level measurement inside a metallic container are reported. © 2006 IEEE.

Allmaier H.,Virtual Vehicle Competence Center | Priestner C.,Virtual Vehicle Competence Center | Six C.,Virtual Vehicle Competence Center | Priebsch H.H.,Virtual Vehicle Competence Center | And 2 more authors.
Tribology International | Year: 2011

It is the aim of this work to predict friction in journal bearings reliably and accurately under realistic dynamic working conditions. To this purpose elastohydrodynamic (EHD) calculations using an extensive oil-model and including an approach to the conformal roughnesses of the bearing surfaces are carried out for transient loads typical for current utility vehicles (40 MPa) as well as for considerably higher specific loads (70 MPa) and for different lubricants (SAE10, SAE20, SAE30 and SAE40) to account for a large span of working conditions ranging from full film lubrication to mixed lubrication with metalmetal contact. The results obtained from this simulation model are compared to measurements performed on a journal bearing test rig. We find that the results of the presented approach agree very closely with the experimental values. The presented approach allows consequently to investigate the effectiveness of changes in bearing geometry, bearing materials, bearing surface roughness, lubricant viscosity and engine operating conditions to reduce friction in journal bearings. © 2011 Elsevier Ltd. All rights reserved.

Priestner C.,Virtual Vehicle Competence Center | Allmaier H.,Virtual Vehicle Competence Center | Priebsch H.H.,Virtual Vehicle Competence Center | Forstner C.,MIBA Bearing Group
Tribology International | Year: 2012

Friction reduction is a fundamental factor in decreasing fuel consumption of internal combustion engines. During the design stage of the engine the simulation of friction in the crank mechanism plays a vital role to develop optimum solutions. Due to the interaction of oil and elastic structures with rough surfaces in slider bearings, complex simulation models have to be used for representing the relevant physical behavior. The following article is focused on crank shaft slider bearings of large engines. The article describes a procedure evaluated by measurements showing how to model wear profiles of slider bearings to reach a high quality friction forecast. A fundamental influencing factor of bearing friction is given by the mixed lubrication regime and it is considered in the simulation model as part of asperity contact friction and hydrodynamic friction. Further effects result from the compliance in radial and width directions of the bearing structure and the wear of the bearing surface. Furthermore, the specific operating conditions of the slider bearing such as load, temperature, shaft speed and oil characteristics are essential and have to be taken into account. The objective of this investigation is to propose the wear profile of the bearing surface for the simulation model to be treated iteratively, where simulation results for the amount of mixed lubrication are successively assessed. For this purpose an iterative procedure is introduced and validated by measurements on a slider bearing test rig. The applied simulation method is based on elastic multi-body systems; the lubrication film contact is calculated based on Reynolds differential equation via the pressure balance calculated iteratively in the time domain. The model accounting for the mixed lubrication regime is based on the theory of Greenwood and Tripp. © 2011 Elsevier Ltd.

Allmaier H.,Virtual Vehicle Competence Center | Priestner C.,Virtual Vehicle Competence Center | Reich F.M.,Virtual Vehicle Competence Center | Priebsch H.H.,Virtual Vehicle Competence Center | And 2 more authors.
Tribology International | Year: 2012

Within the framework of an attempt to predict friction in journal bearings reliably and accurately, the impact of neglecting the hydrodynamic pressure dependence of the lubricant in the oil-model employed in the simulation is investigated. To this task calculations are carried out with two different oil-models; namely, an extensive oil-model that includes the influence of the hydrodynamic pressure on the lubricant properties, as well as the still commonly used basic oil-model that neglects this dependence. To cover full film lubrication and mixed lubrication with significant metalmetal contact, two different lubricants (SAE40, SAE10) are studied. Calculations are conducted using a validated simulation model for dynamic loads with a maximum of up to 76 MPa that exceed typical main bearing loads found in current automotive ICEs. The results for both oil-models are compared to measurements performed on a journal bearing test rig. We find that the results obtained with both oil-models agree closely with the experimental values only for full film lubrication, while solely the extensive oil-model is able to give also reliable results for the case of mixed lubrication. © 2012 Elsevier Ltd. All rights reserved.

Allmaier H.,Virtual Vehicle Competence Center | Priestner C.,Virtual Vehicle Competence Center | Reich F.M.,Virtual Vehicle Competence Center | Priebsch H.H.,Virtual Vehicle Competence Center | Novotny-Farkas F.,OMV Austria Exploration and Production GmbH
Tribology International | Year: 2013

In a previous work an elastohydrodynamic (EHD) simulation model was presented to predict the frictional losses within journal bearings and validated with a large set of measurements. In the current work this simulation model is extended to a thermoelastohydrodynamic (TEHD) simulation to take into account the influence of local temperatures within the bearing. Detailed comparisons of the results between the two models show that for full film lubricated and even slightly mixed lubricated working conditions the inclusion of local temperatures results in rather small corrections to the properties studied. In addition, a method is developed from the TEHD-results to estimate a representative global oil temperature for single bearings to predict friction with the EHD-model. © 2012 Elsevier Ltd.

Lechner B.,Virtual Vehicle Competence Center | Lieschnegg M.,Virtual Vehicle Competence Center | Mariani O.,Virtual Vehicle Competence Center | Pircher M.,Advanced Bridge Engineering Systems | Fuchs A.,Virtual Vehicle Competence Center
International Journal on Smart Sensing and Intelligent Systems | Year: 2010

Bridge Weigh-in-Motion systems can be used to estimate vehicle parameters such as velocity, axle loads, or the distance between axles without affecting the traffic. These parameters and the classification of vehicles are necessary to determine vehicle overload and hence may help to reduce risks for road users and road infrastructure and allow optimized planning of maintenance work. The Bridge Weigh-in-Motion system developed is based on a crack displacement sensor with intelligent data processing algorithms: In a first step, the number of axles, the distance between axles, and the velocity of the vehicle is obtained from the crack displacement signal by means of wavelet decomposition. In a subsequent step, the axle loads are found by means of optimizing the weights for axle loads that the measured crack displacement signal can be approximated by a superposition of (shifted and extended/compressed) 'Lines of Influence'. Intensive test runs have been performed to verify results of the Bridge Weigh-in-Motion system.

Karner M.,Graz University of Technology | Armengaud E.,Virtual Vehicle Competence Center | Steger C.,Graz University of Technology | Weiss R.,Graz University of Technology
Proceedings -Design, Automation and Test in Europe, DATE | Year: 2010

Automotive network technologies such as FlexRay present a cost-optimized structure in order to tailor the system to the required functionalities and to the environment. The space exploration for optimization of single components (cable, transceiver, communication controller, middleware, application) as well as the integration of these components (e.g. selection of the topology) are complex activities that can be efficiently supported by means of simulation. The main challenge while simulating communication architectures is to efficiently integrate the heterogeneous models in order to obtain accurate results for a relevant operation time of the system. In this work, a run-time model switching method is introduced for the holistic simulation of FlexRay networks. Based on a complete modeling of the main network components, the simulation performance increase is analyzed and the new test and diagnosis possibilities resulting from this holistic approach are discussed. © 2010 EDAA.

Lieschnegg M.,Virtual Vehicle Competence Center | Lechner B.,Virtual Vehicle Competence Center | Fuchs A.,Virtual Vehicle Competence Center | Mariani O.,Virtual Vehicle Competence Center
International Journal on Smart Sensing and Intelligent Systems | Year: 2011

This paper presents the development of a versatile sensor platform used for autonomous data acquisition. The key advantages of the platform are its compact design, implemented onboard sensors, standard interfaces to connect application specific sensors and subsequently simple installation and low costs for the preparation of a measurement task. The paper provides details of the platform design and key characteristics. Practical exemplary applications in the field of automotive sensing, covering thermal management related and passenger comfort related measurement tasks, are presented.

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