References of "Voos, Holger 50003283"
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See detailObserver-Based Approach for Fractional-Order Chaotic Synchronization and Communication
Ndoye, Ibrahima UL; Darouach, Mohamed; Voos, Holger UL

in European Control Conference (ECC), July 17-19, 2013, Switzerland (2013)

This paper presents a method based on the state observer design for constructing a chaotically synchronized systems. Fractional-order direct Lyapunov theorem is used to derive the closed-loop asymptotic ... [more ▼]

This paper presents a method based on the state observer design for constructing a chaotically synchronized systems. Fractional-order direct Lyapunov theorem is used to derive the closed-loop asymptotic stability. The gains of the observer and observer-based controller are obtained in terms of linear matrix inequalities (LMIs) formulation. The proposed approach is then applied to secure communications. The method combines chaotic masking and chaotic modulation, where the information signal is injected into the transmitter and simultaneously transmitted to the receiver. Chaotic synchronization and chaotic communication are achieved simultaneously via a state observer design technique. An numerical fractional-order chaotic Lorenz system is given to demonstrate the applicability of the proposed approach. [less ▲]

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See detailObserver-Based Approach for Fractional-Order Chaotic Synchronization and Communication
Ndoye, Ibrahima UL; Darouach, Mohamed; Voos, Holger UL

in European Control Conference (ECC), Switzerland, July 17-19, 2013 (2013)

This paper presents a method based on the state observer design for constructing a chaotically synchronized systems. Fractional-order direct Lyapunov theorem is used to derive the closed-loop asymptotic ... [more ▼]

This paper presents a method based on the state observer design for constructing a chaotically synchronized systems. Fractional-order direct Lyapunov theorem is used to derive the closed-loop asymptotic stability. The gains of the observer and observer-based controller are obtained in terms of linear matrix inequalities (LMIs) formulation. The proposed approach is then applied to secure communications. The method combines chaotic masking and chaotic modulation, where the information signal is injected into the transmitter and simultaneously transmitted to the receiver. Chaotic synchronization and chaotic communication are achieved simultaneously via a state observer design technique. An numerical fractional-order chaotic Lorenz system is given to demonstrate the applicability of the proposed approach. [less ▲]

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See detailUtilizing Dynamic Hazard Knowledge for Risk Sensitive Action Planning of Autonomous Robots
Ertle, P.; Voos, Holger UL; Soeffker, D.

in IEEE Int. Symposium on Robotics and Sensor Environments ROSE, Magdeburg, Germany, 2012 (2012)

Autonomous robots are required to perform tasks in complex and dynamic environments. For this class of systems, traditional safety assuring methods are not satisfying due to the unknown effects of the ... [more ▼]

Autonomous robots are required to perform tasks in complex and dynamic environments. For this class of systems, traditional safety assuring methods are not satisfying due to the unknown effects of the interacting system with an open environment. Briefly speaking: What is not known during the development phase can not be adequately considered. In order to tackle this problem, it is proposed to extend the safety measures with the so-called dynamic risk assessment. Therefore, the anticipatory capability of a Cognitive Technical System, the so-called mental action space, is utilized. The mental action space, a learned internal representation for possible courses of action, is dynamically assessed. The proposed dynamic risk assessment module provides this functionality. The core are quantitative risk models, so-called ‘safety principles’, which can be specified during the system’s design stage without losing the possibility to be adjusted or extended during the system’s operating time. Finally, an exemplary application of the approach shows a robot, enabled to safely plan and perform its tasks concerning risks arising due to interaction of robot and environment. [less ▲]

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See detailEngineering Process for Safe Autonomous Robots
Gribov, Vladislav UL; Voos, Holger UL

in Abstract book of 5th International Workshop on Human-Friendly Robotics (HFR2012) (2012)

Safe service and personal care robots became new exciting research topic over last few years. Physical segregation of the industrial robot and humans works fine [1], but for obvious reasons is not ... [more ▼]

Safe service and personal care robots became new exciting research topic over last few years. Physical segregation of the industrial robot and humans works fine [1], but for obvious reasons is not possible if physical human-robot interaction (pHRI) is required. Autonomous robots and untrained humans sharing the operation space and cooperating with each other brings new kind of risks and requirements to robot safety. The wide deployment of service and personal care robots suggests limited costs for the robot development phase. The existing robots, both industrial and academic, are mostly designed from scratch without providing clear and safetyoriented engineering process for robot design. [less ▲]

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See detailStatic Output Feedback Stabilization of Nonlinear Fractional-Order Glucose-Insulin System
Ndoye, Ibrahima UL; Voos, Holger UL; Darouach, Mohamed et al

in IEEE EMBS Conference on Biomedical Engineering and Sciences, Malaysia, 17th - 19th December, 2012 (2012)

Diabetes is a long-term disease during which the body's production and use of the insulin are impaired, causing glucose concentration level to increase in the bloodstream. The blood glucose dynamics is ... [more ▼]

Diabetes is a long-term disease during which the body's production and use of the insulin are impaired, causing glucose concentration level to increase in the bloodstream. The blood glucose dynamics is described using the generalized minimal model structure for the intravenously infused insulin blood glucose, which can represent a wide variety of diabetic patients. In this paper, it is an attempt to incorporate fractional-order derivative into the mathematical minimal model of glucose-insulin system dynamics and it is still an interesting challenge to determine, mathematically, how the order of a fractional differential system affects the dynamics of system. The paper presents the asymptotical stabilization problem of nonlinear fractional-order glucose insulin systems. A static output feedback control is considered for the problem. Sufficient conditions for the asymptotical stabilization of the nonlinear fractional-order glucose-insulin system are derived in terms of linear matrix inequalities (LMIs) formulation by using the fractional Lyapunov direct method where the fractional-order \alpha belonging to 0<\alpha<1. Finally, numerical simulations are carried out to illustrate our proposed results. These numerical simulations show that the nonlinear fractional-order glucose-insulin systems are, at least, as stable as their integer-order counterpart. [less ▲]

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See detailAn Unknown Input Fractional-Order Observer Design for Fractional-Order Glucose-Insulin System
Ndoye, Ibrahima UL; Voos, Holger UL; Darouach, Mohamed et al

in IEEE EMBS Conference on Biomedical Engineering and Sciences, Malaysia, 17th - 19th December, 2012 (2012)

In this paper, we introduce fractional-order derivatives into a generalized minimal model of glucose-insulin. A fractional-order state observer is designed for estimating the structure of a blood glucose ... [more ▼]

In this paper, we introduce fractional-order derivatives into a generalized minimal model of glucose-insulin. A fractional-order state observer is designed for estimating the structure of a blood glucose-insulin with glucose rate disturbance to show the complete dynamics of the glucose-insulin system where the fractional-order \alpha belonging to 0<\alpha<1. A nonlinear fractional-order unknown input observer strategy is used where the glucose rate disturbance is considered as an unknown input to the perspective dynamical system. The developed method provides the observer estimation algorithm for a glucose-insulin system with unknown time-varying glucose rate disturbance. The stability analysis of the fractional-order error system is completed and showed that the fractional-order observer design is as stable as their integer-order counterpart and guarantees the best convergence of the estimation error. Finally, numerical simulations are given to illustrate the effectiveness of the proposed method. [less ▲]

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See detailConceptual Design of a Dynamic Risk-Assessment Server for Autonomous Robots
Ertle, P.; Tokic, M.; Bystricky, T. et al

in 7th German Conference on Robotics (Robotik 2012) (2012)

Future autonomous service robots are intended to operate in open and complex environments. This in turn implies complications ensuring safe operation. The tenor of few available investigations is the need ... [more ▼]

Future autonomous service robots are intended to operate in open and complex environments. This in turn implies complications ensuring safe operation. The tenor of few available investigations is the need for dynamically assessing operational risks. Furthermore, there is a new kind of hazards being implicated by the robot’s capability to manipulate the environment: Hazardous environmental object interactions. Therefore, the realization of the Dynamic Risk-Assessment approach with special scope on object-interaction risks is addressed in this paper. A server-based architecture is proposed facilitating a feasible integration into robotic systems and realization of software and hardware redundancy as well. [less ▲]

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See detailRobust Exploration/Exploitation Trade-Offs in Safety-Critical Applications
Tokic, M.; Ertle, P.; Palm, G. et al

in 8th IFAC Int. Symposium on Fault Detection, Supervision and Safety for Technical Processes, Mexico City 29-31 August 2012 (2012)

With regard to future service robots, unsafe exceptional circumstances can occur in complex systems that are hardly to foresee. In this paper, the assumption of having no knowledge about the environment ... [more ▼]

With regard to future service robots, unsafe exceptional circumstances can occur in complex systems that are hardly to foresee. In this paper, the assumption of having no knowledge about the environment is investigated using reinforcement learning as an option for learning behavior by trial-and-error. In such a scenario, action-selection decisions are made based on future reward predictions for minimizing costs in reaching a goal. It is shown that the selection of safetycritical actions leading to highly negative costs from the environment is directly related to the exploration/exploitation dilemma in temporal-di erence learning. For this, several exploration policies are investigated with regard to worst- and best-case performance in a dynamic environment. Our results show that in contrast to established exploration policies like epsilon-Greedy and Softmax, the recently proposed VDBE-Softmax policy seems to be more appropriate for such applications due to its robustness of the exploration parameter for unexpected situations. [less ▲]

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See detailModel-based Product and Process Integration for Enhanced Collaboration during Mechatronic Design Processes
Seemueller, H.; Voos, Holger UL

in 2nd Workshop on Process-based Approaches for Model-Driven Engineering PMDE, Copenhagen 2-5 July 2012 (2012)

The collaborative design of mechatronic systems is still a challenging task as di erent engineering disciplines have to be considered and coordinated during the design process. Here, an independent and ... [more ▼]

The collaborative design of mechatronic systems is still a challenging task as di erent engineering disciplines have to be considered and coordinated during the design process. Here, an independent and isolated view on discipline-speci c tools, model data and activities is not appropriate. So, the integration of these aspects for improved collaboration is still a remaining task in industry and research. Former research have already developed rst solutions each directing into the integration of distinct aspects among the involved disciplines. This paper claims that a comprehensive view on the di erent aspects can bring signi cant bene ts for the design of mechatronic systems. In detail, it presents an approach which combines interdisciplinary system modeling with design activity management by describing and integrating these aspects on metalevel. This integration leads automatically to enhanced possibilities for design activity coordination and monitoring. [less ▲]

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See detailInterdisciplinary System Model for Agent-based Mechatronic Design of Turbocharging Systems
Schmelcher, J.; Stetter, R.; Kaufmann, A. et al

in International Design Conference -DESIGN 2012 (2012)

The advances in technology and science lead to the creation of mechatronic systems with increasing complexity. Due to this rising complexity of the systems to be developed, the requirements towards the ... [more ▼]

The advances in technology and science lead to the creation of mechatronic systems with increasing complexity. Due to this rising complexity of the systems to be developed, the requirements towards the development processes are ascending in the same manner. As a result of the historical evolution of the involved domains (mechanical engineering, electrical engineering and computer science), the specific IT-Tools were not designed for interdisciplinary processes and can usually even barely exchange data among each other. This causes a lack of interoperability and results in ineffective development processes with drawbacks on the consistency of interdisciplinary model data. To deal with this situation, research and industry encouraged the idea of a domain-spanning system model, which contains the cross-domain information and important relations (e. g. Chen et al. 2009). One promising approach to survey these interdisciplinary information and relations and thus help the people participating in the design process is based on multi-agent systems. The basis on which a multi-agent system is able to make decisions concerning the cross-domain information and relations can be a model of the mechatronic system modelled with the modelling language SysML. This paper will present an approach how this system models can be developed using the modelling language SysML and furthermore it will expound a practical model of a real mechatronic system – a turbocharging system for a car engine. [less ▲]

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See detailAn Nonparametric Evaluation of SysML-Based Mechatronic Conceptual Design
Chami, Mohammad; Bou Ammar, Haitham; Voos, Holger UL et al

in Proceedings, 24th Benelux Conference on Artificial Intelligence (2012)

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See detailTowards Learning of Safety Knowledge from Human Demonstrations
Ertle, P.; Tokic, M.; Cubek, R. et al

in IEEE/RSJ Int. Conference on Intelligent Robots and Systems IROS, Vilamoura 7-12 Oct. 2012 (2012)

Future autonomous service robots are intended to operate in open and complex environments. This in turn implies complications ensuring safe operation. The tenor of few available investigations is the need ... [more ▼]

Future autonomous service robots are intended to operate in open and complex environments. This in turn implies complications ensuring safe operation. The tenor of few available investigations is the need for dynamically assessing operational risks. Furthermore, a new kind of hazards being implicated by the robot’s capability to manipulate the environment occurs: hazardous environmental object interactions. One of the open questions in safety research is integrating safety knowledge into robotic systems, enabling these systems behaving safety-conscious in hazardous situations. In this paper a safety procedure is described, in which learning of safety knowledge from human demonstration is considered. Within the procedure, a task is demonstrated to the robot, which observes object-to-object relations and labels situational data as commanded by the human. Based on this data, several supervised learning techniques are evaluated used for finally extracting safety knowledge. Results indicate that Decision Trees allow interesting opportunities. [less ▲]

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See detailVisual Attitude Estimation for Low-Cost Personal Remote Sensing Systems
Fromm, Tobias; Di, Long; Chen, Yangquan et al

in 7th International ASME/IEEE Conference on Mechatronics & Embedded Systems & Applications MESA 2011, Washington 28-31 August 2011 (2011, August 29)

Remote Sensing using unmanned aerial vehicles (UAV) is gathering a lot of attention at the moment by researchers and developers, especially in terms of low-cost aircrafts which still maintain sufficient ... [more ▼]

Remote Sensing using unmanned aerial vehicles (UAV) is gathering a lot of attention at the moment by researchers and developers, especially in terms of low-cost aircrafts which still maintain sufficient accuracy and performance. This paper introduces a low-cost approach to increase airworthiness by using a forward-looking camera to estimate the attitude of a UAV. It not only focuses on using machine learning to classify ground and sky, but also uses image processing and software engineering methods to make it fault-tolerant and really applicable on a miniature UAV. Additionally, it is able to interface with an autopilot framework to being used productively on flight missions. [less ▲]

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See detailA MATLAB-based Application Development Using a 3D PMD Camera for a Mobile Robot
Chami, Mohammad; Voos, Holger UL

in 7th International ASME/IEEE Conference on Mechatronics & Embedded Systems & Applications MESA 2011, Washington, USA, 2011 (2011)

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See detailInterdisciplinary System Model for Agent-Supported Mechatronic Design
Stetter, Ralf; Seemüller, Holger; Chami, Mohammad et al

in International Conference on Engineering Design ICED`11, Copenhagen, 2011 (2011)

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See detailCollaborative Nonlinear Model-Predictive Motion Planning and Control of Mobile Transport Robots for a Highly Flexible Production System
Wangmanaopituk, Suparchoek; Voos, Holger UL; Kongprawechnon, Waree

in ScienceAsia (2010), 36(4), 333-341

This study is based on a new approach for an advanced microproduction system or highly flexible production systems where all necessary production and assembly processes are connected in a very flexible ... [more ▼]

This study is based on a new approach for an advanced microproduction system or highly flexible production systems where all necessary production and assembly processes are connected in a very flexible way using autonomous mobile transport and handling robots. Each robot has to follow its planned paths while avoiding collisions with other robots. In addition, problem-specific constraints for a defined microproduction system, such as limitations of the velocity and accelerations of the robots, have to be fulfilled. This paper focuses on a two-level model predictive optimizing approach. On a global long-term level, simple dynamic models of the robots are used to compute optimal paths under differential constraints where a safety distance between all robots is achieved. Since many uncertainties and unforeseen events could occur, all robots also use a nonlinear model predictive control approach on a local real-time level. This control approach solves the path following and the collision avoidance problems in parallel, while also taking into account differential constraints of the single robots. [less ▲]

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See detailGrundkurs der Regelungstechnik: Einführung in die praktischen und theoretischen Methoden
Jaschek, Hilmar; Voos, Holger UL

Book published by Oldenbourg Wissenschaftsverlag - 16. Aufl. (2010)

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See detailIn-Situ Unmanned Aerial Vehicle Sensor Calibration to Improve Automatic Image Orthorectification
Jensen, Austin; Wildmann, Norman; Chen, Yangquan et al

in IEEE Int. Geoscience and Remote Sensing Symposium; honolulu, USA, 2010 (2010)

Small, low-altitude unmanned aerial vehicles (UAV)s can be very useful in many ecological applications as a personal remote sensing platform. However, in many cases it is difficult to produce a single ... [more ▼]

Small, low-altitude unmanned aerial vehicles (UAV)s can be very useful in many ecological applications as a personal remote sensing platform. However, in many cases it is difficult to produce a single georeferenced mosaic from the many small images taken from the UAV. This is due to the lack of features in the images and the inherent errors from the inexpensive navigation sensors. This paper focuses on improving the orthorectification accuracy by finding these errors and calibrating the navigation sensors. This is done by inverseorthorectifying a set of images collected during flight using ground targets and General Procrustes Analysis. By comparing the calculated data from the inverse-orthorectification and the measured data from the navigation sensors, different sources of errors can be found and characterized, such as GPS computational delay, logging delay, and biases. With this method, the orthorectification errors are reduced from less than 60m to less than 1.5m. [less ▲]

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See detailDevelopment of Safe Autonomous Mobile Service Robots using an Active Integrated Approach
Voos, Holger UL; Ertle, Philipp; Söffker, Dirk

in 41st International Symposium on Robotics (ISR) 2010, Munich, Germany (2010)

Mobile service robots are expected to provide services in various domains of life. Herein, the main challenge for the robot is the execution of complex tasks within an unstructured dynamic environment. In ... [more ▼]

Mobile service robots are expected to provide services in various domains of life. Herein, the main challenge for the robot is the execution of complex tasks within an unstructured dynamic environment. In order to achieve the necessary highly flexible behavior, mobile service robots must have a high degree of autonomy. However, although much effort is spent on the investigation and realization of autonomy since decades, it is mostly neglected, that autonomous robots are also causing new types of safety problems. It seems impossible to solve these problems with traditional passive safety approaches. Therefore, new methods are introduced in order to check safety during operation time. [less ▲]

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See detailSituational Method Engineering applied for the Enactment of Development Processes: An Agent-based Approach
Seemüller, Holger; Voos, Holger UL; Honke, B. et al

in 12th Int. Conference on Enterprise Information Systems ICEIS 2010, Funchal, Portugal, 2010 (2010)

Interdisciplinary product development is faced with the collaboration of diverse roles and a multitude of interrelated artifacts. Traditional and sequential process models cannot deal with the long ... [more ▼]

Interdisciplinary product development is faced with the collaboration of diverse roles and a multitude of interrelated artifacts. Traditional and sequential process models cannot deal with the long-lasting and dynamic behavior of the development processes of today. Moreover, development processes have to be tailored to the needs of the projects, which are usually distributed today. Thus, keeping these projects on track from a methodology point of view is difficult. In order to deal with these challenges, this paper will present a novel method engineering and enactment approach. It combines the ideas of workflow technologies and product line engineering for method engineering as well as agent technology for the development process enactment. [less ▲]

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