References of "Voos, Holger 50003283"
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See detailA Modularization Approach for Nonlinear Model Predictive Control of Distributed Fast Systems
Dentler, Jan Eric UL; Kannan, Somasundar UL; Olivares Mendez, Miguel Angel UL et al

in 24th Mediterranean Conference on Control and Automation (MED), Athens, Greece, June 21-24, 2016 (2016, June 22)

Distributed interconnected systems are omnipresent today. The development of advanced control methods for such systems are still challenging. Herein, the real-time applicability, flexibility, portability ... [more ▼]

Distributed interconnected systems are omnipresent today. The development of advanced control methods for such systems are still challenging. Herein, the real-time applicability, flexibility, portability and ease of implementation are issues of the existing control solutions, especially for more advanced methods such as model predictive control. This paper is addressing these issues by presenting an efficient modular composition scheme for distributed fast nonlinear systems. The advantage of this modularization approach is the capability of changing control objectives, constraints, dynamics and system topology online while maintaining fast computation. This work analyzes the functions that have to be provided for a continuation generalized minimal residual method (CGMRES) model predictive controller based on the underlying control problem. The specific structure of these functions allows their decomposition into suitable fast modules. These modules are then used to recompose the functions which are required for the control of distributed systems in a computational efficient way, while maintaining the flexibility to dynamically exchange system parts. To validate this computational efficiency, the computation time of the proposed modular control approach is compared with a standard nonmodular implementation in a pursuit scenario of quadrotor unmanned aerial vehicles (UAV). Furthermore the real-time applicability is discussed for the given scenario. [less ▲]

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See detailNonlinear Model Predictive Extended Eco-Cruise Control for Battery Electric Vehicles
Sajadi Alamdari, Seyed Amin UL; Voos, Holger UL; Darouach, Mohamed

in 24th Mediterranean Conference on Control and Automation (MED), Athens, Greece, 2016 (2016, June 22)

Battery Electric Vehicles are becoming a promising technology for road transportation. However, the main disadvantage is the limited cruising range they can travel on a single battery charge. This paper ... [more ▼]

Battery Electric Vehicles are becoming a promising technology for road transportation. However, the main disadvantage is the limited cruising range they can travel on a single battery charge. This paper presents a novel extended ecological cruise control system to increase the autonomy of an electric vehicle by using energy-efficient driving techniques. Driven velocity, acceleration profile, geometric and traffic characteristics of roads largely affect the energy consumption. An energy-efficient velocity profile should be derived based on anticipated optimal actions for future events by considering the electric vehicle dynamics, its energy consumption relations, traffic and road geometric information. A nonlinear model predictive control method with a fast numerical algorithm is adapted to determine proper velocity profile. In addition, a novel model to describe the energy consumption of a series- production electric vehicle is introduced. The hyperfunctions concept is used to model traffic and road geometry data in a new way. The proposed system is simulated on a test track scenario and obtained results reveal that the extended ecological cruise control can significantly reduce the energy consumption of an electric vehicle. [less ▲]

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See detailA Polytopic Approach for the Nonlinear Unknown Input Functional Observers Design: Application to a Quadrotor Aerial Robots Landing
Bezzaoucha, Souad UL; Voos, Holger UL; Darouach, Mohamed

in 2016 European Control Conference (ECC), Aalborg, Denmark (2016, June)

This paper considers a method of designing functional observers for continuous time nonlinear systems subject to unknown inputs. The proposed approach consists in rewriting the nonlinear model in a ... [more ▼]

This paper considers a method of designing functional observers for continuous time nonlinear systems subject to unknown inputs. The proposed approach consists in rewriting the nonlinear model in a polytopic form (also known as multiple or Takagi-Sugeno models) applying the Sector Nonlinearity Transformation (SNT) and then apply the proposed algorithm for the observer design. Sufficient conditions for the asymptotic stability of the estimation error are given in terms of linear matrix inequalities (LMIs) and rank conditions. An application to a quadrotor aerial robots landing is then presented. [less ▲]

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See detailOn the Unknown Input Functional Observers Design: a Polytopic Takagi-Sugeno Approach
Bezzaoucha, Souad UL; Voos, Holger UL; Darouach, Mohamed

in 24th Mediterranean Conference on Control and Automation (MED), Athens, Greece, 2016 (2016, June)

In this paper, a step by step algorithm is given to design functional unknown input observer for continuous nonlinear systems under the Polytopic Takagi-Sugeno (T-S) framework. To nullify the effect of ... [more ▼]

In this paper, a step by step algorithm is given to design functional unknown input observer for continuous nonlinear systems under the Polytopic Takagi-Sugeno (T-S) framework. To nullify the effect of unknown input (UI), classical approach of decoupling the UI for the linear case is extended to the polytopic system. Applying the Lyapunov theory and the L2 attenuation, Linear Matrix Inequalities (LMI)s conditions are achieved which are solved for feasibility to obtain observer design matrices. The novelty of the proposed approach consists in solving simultaneously both structural constraints and LMIs, which ensure a mean for the efficient design of the gains of the observers. To illustrate the proposed theoretical results, simulation example of a Waste Water Treatment Plant (WWTP), which is highly nonlinear and represented in a T-S polytopic form with unmeasurable premise variables and unknown inputs, is discussed. [less ▲]

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See detailA Flexible Move Blocking Strategy to Speed up Model-Predictive Control while Retaining a High Tracking Performance
Schwickart, Tim Klemens UL; Voos, Holger UL; Darouach, Mohamed et al

in 2016 European Control Conference (ECC), Aalborg, Denmark (2016, June)

This paper presents a strategy to reduce the complexity and thus the computational burden in modelpredictive control (MPC) by a flexible online input move blocking algorithm. Model-predictive sampled-data ... [more ▼]

This paper presents a strategy to reduce the complexity and thus the computational burden in modelpredictive control (MPC) by a flexible online input move blocking algorithm. Model-predictive sampled-data control of constrained, LTI plants is considered. Move blocking is an input parameterisation in MPC where the control input is forced to be constant over several prediction sample steps to reduce the dimensionality of the underlying optimisation problem. Typically, the prediction sample steps where the control input is not allowed to vary (i. e. the block distribution) is predetermined offline and is kept constant throughout the control operation. However, the control performance and computational efficiency can be improved if the block length is adjusted to the specific operating conditions. In this work, a heuristic method to adjust the block length online according to the initial state of the system, reference signals, measured disturbances and constraints is presented. A numerical example shows the effectiveness of the approach. [less ▲]

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See detailGeneralized Wake Interaction Models and Optimal Control in Wind Farms
Pan, Lin UL; Voos, Holger UL; Darouach, Mohamed

in 28th Control and Decision Conference (CCDC), China, 2016 (2016, May 28)

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See detailVision-Based Steering Control, Speed Assistance and Localization for Inner-CityVehicles
Olivares Mendez, Miguel Angel UL; Sanchez-Lopez, Jose Luis; Jimenez, Felipe et al

in Sensors (2016), 16(3), 362

Autonomous route following with road vehicles has gained popularity in the last few decades. In order to provide highly automated driver assistance systems, different types and combinations of sensors ... [more ▼]

Autonomous route following with road vehicles has gained popularity in the last few decades. In order to provide highly automated driver assistance systems, different types and combinations of sensors have been presented in the literature. However, most of these approaches apply quite sophisticated and expensive sensors, and hence, the development of a cost-efficient solution still remains a challenging problem. This work proposes the use of a single monocular camera sensor for an automatic steering control, speed assistance for the driver and localization of the vehicle on a road. Herein, we assume that the vehicle is mainly traveling along a predefined path, such as in public transport. A computer vision approach is presented to detect a line painted on the road, which defines the path to follow. Visual markers with a special design painted on the road provide information to localize the vehicle and to assist in its speed control. Furthermore, a vision-based control system, which keeps the vehicle on the predefined path under inner-city speed constraints, is also presented. Real driving tests with a commercial car on a closed circuit finally prove the applicability of the derived approach. In these tests, the car reached a maximum speed of 48 km/h and successfully traveled a distance of 7 km without the intervention of a human driver and any interruption. [less ▲]

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See detailNew unified H-infinity dynamic observer design for linear systems with unknown inputs
Gao, Nan; Darouach, Mohamed; Voos, Holger UL et al

in Automatica (2016), 65

In this paper, a unified dynamic observer (UO) is proposed for a class of linear systems in the presence of unknown inputs and disturbances. It generalizes the existing results on the proportional ... [more ▼]

In this paper, a unified dynamic observer (UO) is proposed for a class of linear systems in the presence of unknown inputs and disturbances. It generalizes the existing results on the proportional observer (PO), the proportional integral observer (PIO) and the dynamic observer (DO). The design approach of the UO is derived from the solution of the linear matrix inequality (LMI), based on the new dynamic observer formulation and the solution of the algebraic constraints obtained from the unbiased estimation error. A numerical example is provided to show the applicability and the performance of our results. [less ▲]

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See detailAdaptive Control of Robotic arm with Hysteretic Joint
Kannan, Somasundar UL; Bezzaoucha, Souad UL; Quintanar Guzman, Serket UL et al

in 4th International Conference on Control, Mechatronics and Automation (ICCMA'16), Barcelona, Spain 2016 (2016)

This article addresses the problem of control of robotic arm with a hysteretic joint behavior. The mechanical design of the one-degree of freedom robotic arm is presented where the joint is actuated by a ... [more ▼]

This article addresses the problem of control of robotic arm with a hysteretic joint behavior. The mechanical design of the one-degree of freedom robotic arm is presented where the joint is actuated by a Shape Memory Alloy (SMA) wire. The SMA wire based actuation of the joint makes the robotic arm lightweight but at the same time introduces hysteresis type nonlinearities. The nonlinear dynamic model of the robotic arm is introduced and an Adaptive control solution is presented to perform the joint reference tracking in the presence of unknown hysteresis behavior. The Lyapunov stability analysis of the closed loop system is presented and finally proposed adaptive control solution is validated through simulation study on the proposed nonlinear hysteretic robotic arm. [less ▲]

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See detailModel Predictive Control for Spacecraft Rendezvous
Kannan, Somasundar UL; Sajadi Alamdari, Seyed Amin UL; Dentler, Jan Eric UL et al

in 4th International Conference on Control, Mechatronics and Automation ICCMA '16, Barcelona, Spain, 2016 (2016)

The current paper addresses the problem of Spacecraft Rendezvous using Model Predictive Control (MPC). The Clohessy-Wiltshire-Hill equations are used to model the spacecraft relative motion. Here the ... [more ▼]

The current paper addresses the problem of Spacecraft Rendezvous using Model Predictive Control (MPC). The Clohessy-Wiltshire-Hill equations are used to model the spacecraft relative motion. Here the rendezvous problem is discussed by trajectory control using MPC method. Two different scenarios are addressed in trajectory control. The first scenario consist of position control with fuel constraint, secondly the position control is performed in the presence of obstacles. Here the problem of fuel consumption and obstacle avoidance is addressed directly in the cost function. The proposed methods are successfully analysed through simulations. [less ▲]

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See detailCollaborative Explanation and Response in Assisted Living Environments Enhanced with Humanoid Robots
bikakis, Antonis; Caire, Patrice UL; clark, keith et al

in 8th International Conference on Agents and Artificial Intelligence, ICAART, Rome, Italy, 2016 (2016)

An ageing population with increased social care needs has provided recent impetus for research into assisted living technologies, as the need for different approaches to providing supportive environments ... [more ▼]

An ageing population with increased social care needs has provided recent impetus for research into assisted living technologies, as the need for different approaches to providing supportive environments for senior citi- zens becomes paramount. Ambient intelligence (AmI) systems are already contributing to this endeavour. A key feature of future AmI systems will be the ability to identify causes and explanations for changes to the environment, in order to react appropriately. We identify some of the challenges that arise in this respect, and argue that an iterative and distributed approach to explanation generation is required, interleaved with di- rected data gathering. We further argue that this can be realised by developing and combining state-of-the art techniques in automated distributed reasoning, activity recognition, robotics, and knowledge-based control. [less ▲]

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See detailTowards an Autonomous Vision-Based Unmanned Aerial System against Wildlife Poachers
Olivares Mendez, Miguel Angel UL; Fu, Changhong; Ludivig, Philippe et al

in Sensors (2015), 15(12), 29861

Poaching is an illegal activity that remains out of control in many countries. Based on the 2014 report of the United Nations and Interpol, the illegal trade of global wildlife and natural resources ... [more ▼]

Poaching is an illegal activity that remains out of control in many countries. Based on the 2014 report of the United Nations and Interpol, the illegal trade of global wildlife and natural resources amounts to nearly $213 billion every year, which is even helping to fund armed conflicts. Poaching activities around the world are further pushing many animal species on the brink of extinction. Unfortunately, the traditional methods to fight against poachers are not enough, hence the new demands for more efficient approaches. In this context, the use of new technologies on sensors and algorithms, as well as aerial platforms is crucial to face the high increase of poaching activities in the last few years. Our work is focused on the use of vision sensors on UAVs for the detection and tracking of animals and poachers, as well as the use of such sensors to control quadrotors during autonomous vehicle following and autonomous landing. [less ▲]

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See detailA Class of Improved Wake Interaction Model for the Coordinated Control of Wind Farms
Pan, Lin UL; Voos, Holger UL; Darouach, Mohamed

in IEEE Conference Publications (Ed.) IEEE International Chinese Automation Congress (CAC), 2015 (2015, December 01)

This paper is focused on the Wind Energy (WE) systems and Wind Farms (WFs) optimization in Luxembourg. It describes the overview of the wind resources in all the WFs and presents a class of Improved Wake ... [more ▼]

This paper is focused on the Wind Energy (WE) systems and Wind Farms (WFs) optimization in Luxembourg. It describes the overview of the wind resources in all the WFs and presents a class of Improved Wake Interaction Model (IWIM) for Coordination and Optimization Control (CnOC) of WFs. Based on Wind Power (WP) assessment of WFs, the statistical method is used to model the distribution of Wind Speed (WS) and Wind Direction (WD). Some simulation figures about the Wind Rose (WR) and WF optimization demonstrate the description and assessment of WP in detail. These assessments are expected to enhance the effectiveness of exploitation and utilization of WP in WFs of Luxembourg. [less ▲]

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See detailRetalis Language for Information Engineering in Autonomous Robot Software
Ziafati, Pouyan UL; dastani, mehdi; meyer, john-jules et al

in IfCoLog Journal of Logics and their Applications (2015), 2(2), 85

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See detailGaussian Filtering for Enhanced Impedance Parameters Identification in Robotic Assembly Processes
Jasim, Ibrahim UL; Plapper, Peter UL; Voos, Holger UL

in 20th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA 2015), Luxembourg 8-11 September 2015 (2015, September 08)

Robot interaction with the environment is normally described as a mass-spring-damping impedance model and the estimation of such interaction impedance parameters requires the computation of the joint (or ... [more ▼]

Robot interaction with the environment is normally described as a mass-spring-damping impedance model and the estimation of such interaction impedance parameters requires the computation of the joint (or task) space velocity and acceleration. In many cases, the velocity and acceleration are computed by numerically computing the first and second derivatives of the sensed position signal. The numerical differentiation results in approximation errors when computing the velocity and acceleration signals that would have a direct impact on the estimation of the impedance parameters. This article proposes enhancing the estimation of the impedance parameters by smoothing the velocity and acceleration signals prior to the considered estimation process. Gaussian Smoothing Filter (GSF) is employed in smoothing the considered signals. After the smoothing process, impedance parameters estimation becomes more feasible using the available strategies like the Least Mean Square (LMS) or any other estimation approach. Experiments are conducted on a KUKA Lightweight Robot (LWR) doing the assembly of the air-intake manifold of an automotive powertrain. The impedance parameters are estimated for the smoothed and unsmoothed cases in order to show the enhancement in the estimation process. [less ▲]

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See detailA Wake Interaction Model for the Coordinated Control of Wind Farms
Pan, Lin UL; Voos, Holger UL; Li, Yumei et al

in Emerging Technologies & Factory Automation (ETFA), 2015 IEEE 20th Conference on (2015, September 08)

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See detailModel-Free Robust Adaptive Control for Flexible Rubber Objects Manipulation
Jasim, Ibrahim UL; Plapper, Peter UL; Voos, Holger UL

in 20th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA 2015), Luxembourg 8-11 September 2015 (2015, September 08)

This article addresses the control problem of robots with unknown dynamics and manipulating flexible rubber objects of unknown elasticity. The manipulated rubber object is considered to be interacting ... [more ▼]

This article addresses the control problem of robots with unknown dynamics and manipulating flexible rubber objects of unknown elasticity. The manipulated rubber object is considered to be interacting with arbitrarily-switched constraints. Such a kind of robot system is shown to have switched impedance parameters during a task execution that results in an unknown hybrid nonlinear system with arbitrarily switched signal. A Model-Free Robust Adaptive Control (MFRAC) strategy is proposed for such a robot system that is proved to guarantee global stable performance with all closed loop signals are assured to be bounded. The suggested MFRAC strategy relies on the synergy of the Adaptive Fuzzy System (AFS), the Sliding Mode Control (SMC), and the notion of Common Lyapunov Functions (CLF). The AFS relaxes the need for knowing the precise robot dynamics, the SMC adds robustness against the drift of the dynamics parameters, and the CLF accommodates the arbitrary switching of the impedance parameters. The bounds of the impedance parameters are adapted online and incorporated in the MFRAC design such that a convergent performance is achieved. Experiment is conducted on a KUKA Lightweight Robot (LWR) doing flexible rubber peg-in-hole assembly process that falls in the category of systems considered in this article. From the experimental results, excellent tracking performance is reported when using the proposed MFRAC strategy for the considered robotic system despite the dynamics anonymity and the unknown impedance parameters arbitrary switching. [less ▲]

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See detailLinearizing Control of Biogas Flow Rate and Quality
Chaib Draa, Khadidja UL; Voos, Holger UL; Alma, Marouane et al

in 20th IEEE Int. Conference on Emerging Tecnologies and Factory Automation ETFA 2015, Luxembourg, 8-11 Sept. 2015 (2015, September)

In this paper, we propose to control the quantity and quality of the produced biogas from the anaerobic digestion of organic matter, digested in either a continuous stirred tank reactor or a fixed bed ... [more ▼]

In this paper, we propose to control the quantity and quality of the produced biogas from the anaerobic digestion of organic matter, digested in either a continuous stirred tank reactor or a fixed bed digester. This is motivated by the aim of providing the power grid with a stable amount of energy despite fluctuations in the treated waste concentration and composition. Therefore, we apply the linearizing control principe to a two step (acidogenesis-methanogenesis) mass balance non linear model, all with the introduction of two new control inputs reflecting the addition of stimulating substrates (acetate and alkalinity). To show the performance of the synthesized control laws we simulate the process under an organic shock load feeding. [less ▲]

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See detailContext-based Selection and Execution of Robot Perception Graphs
Hochgeschwender, Nico UL; Olivares Mendez, Miguel Angel UL; Voos, Holger UL et al

in 20th IEEE International Conference on Emerging Technologies and Factory Automation (ETFA'15) (2015, September)

To perform a wide range of tasks service robots need to robustly extract knowledge about the world from the data perceived through the robot’s sensors even in the presence of varying context-conditions ... [more ▼]

To perform a wide range of tasks service robots need to robustly extract knowledge about the world from the data perceived through the robot’s sensors even in the presence of varying context-conditions. This makes the design and devel- opment of robot perception architectures a challenging exercise. In this paper we propose a robot perception architecture which enables to select and execute at runtime different perception graphs based on monitored context changes. To achieve this the architecture is structured as a feedback loop and contains a repository of different perception graph configurations suitable for various context conditions. [less ▲]

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See detailStatic Output Feedback H-infinity Control for a Fractional-Order Glucose-Insulin System
N'Doye, Ibrahima; Voos, Holger UL; Darouach, Mohamed et al

in International Journal of Control, Automation, and Systems (2015), 13(4), 798-807

This paper presents the H∞ static output feedback control of nonlinear fractional-order systems. Based on the extended bounded real lemma, the H∞ control is formulated and sufficient conditions are ... [more ▼]

This paper presents the H∞ static output feedback control of nonlinear fractional-order systems. Based on the extended bounded real lemma, the H∞ control is formulated and sufficient conditions are derived in terms of linear matrix inequalities (LMIs) formulation by using the fractional Lyapunov direct method where the fractional-order α belongs to 0 < α < 1. The control approach is finally applied to the regulation of the glucose level in diabetes type 1 treatment. Therefore, it is attempted to incorporate fractional-order into the mathematical minimal model of glucose-insulin system dynamics and it is still an interesting challenge to show, how the order of a fractional differential system affects the dynamics of the system in the presence of meal disturbance. Numerical simulations are carried out to illustrate our proposed results and show that the nonlinear fractional-order glucose-insulin systems are, at least, as stable as their integer-order counterpart in the presence of exogenous glucose infusion or meal disturbance. [less ▲]

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