OFFIS

Oldenburg, Germany
Oldenburg, Germany

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Puls T.,OFFIS | Hein A.,OFFIS
IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM | Year: 2010

The demand for unattended aerial aystems capable of fulfilling e.g. surveillance tasks in contaminated or inaccessible areas without assistance of a human pilot is the motivation for the investigation of a high precision position estimation system and an autonomous landing algorithm. Hence, this paper describes the development of a wireless sensor network (WSN) based system able to locate a quadrocopter with an accuracy of less than 5 centimeters. Such systems are needed for high precision autonomous landing tasks. Several measurements show the accuracies of two different methods, a radio- and an ultrasonic-based measurement system. Furthermore, an autonomous landing strategy was implemented on a flight demonstrator for validation and experimental results are provided. © 2010 IEEE.


Puls T.,OFFIS | Hein A.,OFFIS
IEEE/RSJ 2010 International Conference on Intelligent Robots and Systems, IROS 2010 - Conference Proceedings | Year: 2010

The demand for unattended aerial systems capable of fulfilling e.g. surveillance tasks in contaminated or inaccessible areas without any assistance of a human pilot is the motivation for the investigation of a 3D trajectory control. Hence, this paper deals with the development of such a control algorithm able to follow any kind of 3D trajectory within the quadrocopter's capabilities. In this paper the 3D trajectory control algorithm is described. Many simulations were done to find the optimal trajectory course. Further, the control algorithm was implemented on a flight demonstrator for validation and experimental results regarding linear and circle trajectories are provided. ©2010 IEEE.


Schutte S.,OFFIS | Scherfke S.,OFFIS | Sonnenschein M.,OFFIS
SMARTGREENS 2012 - Proceedings of the 1st International Conference on Smart Grids and Green IT Systems | Year: 2012

Simulation is an important method to test and evaluate new control mechanisms for future Smart Grids. To generate sound simulation results one has to use validated and established simulation models. In this paper we present the first two out of six layers of our approach to a modular simulation framework, called mosaik. It will allows to specify, compose and simulate Smart Grid scenarios based on the reuse of existing, technologically heterogeneous simulation models. The layers presented here include a syntactic layer defining an interface for Smart Grid simulators and a semantic layer implemented using a domain-specific language that allows to describe the structure and semantics of the simulator that is interfaced.


Asif A.,University of Oldenburg | Heuten W.,OFFIS | Boll S.,University of Oldenburg
NordiCHI 2010: Extending Boundaries - Proceedings of the 6th Nordic Conference on Human-Computer Interaction | Year: 2010

Visual and auditory displays successfully complement each other presenting information in car navigation systems. However, they distract the visual and auditory attention of the driver, which is needed in many primary driving tasks, such as maneuvering the car or observing the traffic. Tactile interfaces can form an alternative way to display spatial information. The way of how exactly information should be presented in a vibro-tactile way is explored rarely. In this paper we investigate three different designs of vibro-tactile stimulation to convey distance information to the driver using a tactile waist belt. We explore the tactile parameters intensity, rhythm, duration, and body location for encoding the distance information. We conduct a comparative experiment on a real navigation scenario in an urban environment to evaluate our designs. In our study we discovered that rhythm and duration are suitable parameters to generate tactile stimulation for encoding distance information. In this way the driver perceives countable vibro-tactile pulses, which indicate the distance in turn by turn instructions. The approach is found be simple way of encoding complex navigational information. © 2010 ACM.


Pielawa L.,OFFIS | Frenken M.,OFFIS | Hein A.,University of Oldenburg
International Journal of Biomedical Engineering and Technology | Year: 2013

The recent development of more and more autonomous medical devices facilitates unsupervised treatment and thereby saving of costs for healthcare. While flawless control software is needed for such life-critical systems, no specific development processes are established in the medical domain. The here presented approach founds on the functional simulation of system components and their virtual integration as well as modelling of the decisive parts of the physiology influenced by the device. Additionally, a virtual execution platform is integrated enabling to develop the embedded control software and evaluate it online to the functional simulation. Finally, the coupling to an assertion engine for semi-formal verification allows validation of the system's behaviour and its compliance with requirements, specified as assertions. The utilisation of this proposed methodology is demonstrated on the control development for an autonomous dialysis system. The applicability is evaluated and insights gained through its utilisation exemplary demonstrate its benefits. © 2013 Inderscience Enterprises Ltd.


Kuka C.,OFFIS
2012 IEEE International Conference on Pervasive Computing and Communications Workshops, PERCOM Workshops 2012 | Year: 2012

Current autonomic vehicles in outdoor scenarios perform mobility operations with walking speed to ensure safety. For a faster mobility of autonomous vehicles, concrete knowledge of the environment is needed. This will be achieved through a dynamic context model based on sensor data with uncertainties from the environment. These uncertainties arise through existential uncertainty, consistency, and co/variance of and between the sensor data. To allow a flexible processing and to allow different approaches for object detection, object classification, and object tracking, data stream management technology is used. Therefore, a new algebra and operators based on the relational algebra are defined to preserve and process the uncertainties about the sensor data. © 2012 IEEE.


Langner M.,OFFIS | Peinke J.,Carl von Ossietzky University
European Physical Journal B | Year: 2015

A procedure based on stochastic Langevin equations is presented and shows how a stochastic model of driver behavior can be estimated directly from given data. The Langevin analysis allows the separation of a given data-set into a stochastic diffusion- and a deterministic drift field. Form the drift field a potential can be derived. In particular the method is here applied on driving data from a simulator. We overcome typical problems like varying sampling rates, low noise levels, low data amounts, inefficient coordinate systems, and non-stationary situations. From the estimation of the drift- and diffusion vector-fields derived from the data, we show different ways how to set up Monte-Carlo simulations for the driver behavior. © 2015, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.


Schomaker G.,OFFIS | Janacek S.,OFFIS | Schlitt D.,OFFIS
Advances in Intelligent Systems and Computing | Year: 2015

Data centers are the backbone of today’s information technologies. With increasing usage of cloud services and web applications, the need for remote computing and storage will only grow. However, one has to consider that increasing numbers of server and storage systems also mean increases in energy consumption. The power demand is caused not only by the IT hardware, but is also due to the required infrastructure such as power supply and climatization. Therefore, choosing the most appropriate components as well as architectural designs and configurations regarding energy demand, availability, and performance is important. This chapter depicts influencing factors and current trends for these design choices and provides examples. © Springer International Publishing Switzerland 2015.


Heinzemann C.,University of Paderborn | Henkler S.,OFFIS
CompArch'11 - Proceedings of the 2011 Federated Events on Component-Based Software Engineering and Software Architecture - CBSE'11 | Year: 2011

Component based software engineering aims at re-using components in other systems. This requires a verification whether the component can safely interact with its communication partners in a new environment. Such verification is mandatory in case of safety-critical real-time systems where the communication is characterized by a varying number of components instances all being of the same type. Reuse can be facilitated by separating abstract communication protocol definitions and concrete component implementations. In contrast to standard refinement definitions for real-time systems, our definition explicitly takes varying numbers of communication partners into account. Additionally, we relax the strict conditions of a bisimulation to ease reuse of components. Along with our refinement definition, we provide a formal verification procedure to check for correct refinements which preserves properties verified for the abstract protocol definition. We evaluated our approach using a self-adaptive real-time system from the domain of autonomous train systems. The evaluation results show that checking for correct refinements is more efficient than re-verifying the desired properties on the refined component. © 2011 ACM.


Damm W.,OFFIS | Vincentelli A.S.,University of California at Berkeley
2nd International Workshop on the Swarm at the Edge of the Cloud, SWEC 2015 - CPSWEEK 2015 | Year: 2015

In this paper, we present the essential features of CPS Systems of Systems (SoS) and we develop a conceptual, rigorous model for such systems that can support the development of analysis and synthesis tools. We also address issues related to safety critical and secure applications and we outline how to cope with failures of SoS.

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