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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 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 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 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 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 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 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 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 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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See detailAn algebraic detection approach for control systems under multiple stochastic cyber-attacks
Li, Yumei UL; Voos, Holger UL; Darouach, Mohamed et al

in IEEE/CAA Journal of Automatica Sinica (2015), 2(3), 258-266

In order to compromise a target control system successfully, hackers possibly attempt to launch multiple cyberattacks aiming at multiple communication channels of the control system. However, the problem ... [more ▼]

In order to compromise a target control system successfully, hackers possibly attempt to launch multiple cyberattacks aiming at multiple communication channels of the control system. However, the problem of detecting multiple cyber-attacks has been hardly investigated so far. Therefore, this paper deals with the detection of multiple stochastic cyber-attacks aiming at multiple communication channels of a control system. Our goal is to design a detector for the control system under multiple cyberattacks. Based on frequency-domain transformation technique and auxiliary detection tools, an algebraic detection approach is proposed. By applying the presented approach, residual information caused by different attacks is obtained respectively and anomalies in the control system are detected. Sufficient and necessary conditions guaranteeing the detectability of the multiple stochastic cyber-attacks are obtained. The presented detection approach is simple and straightforward. Finally, two simulation examples are provided, and the simulation results show that the detection approach is effective and feasible. [less ▲]

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See detailEffects of Permanent Bounded Cyber-Attacks on Networked Control Systems
Gerard, Benjamin UL; Voos, Holger UL; Li, Yumei UL et al

in 23rd Mediterranean Conference on Control and Automation (MED) (2015, June 16)

In this paper, the problem of permanent bounded cyber-attacks on networked control systems is treated. After a characterisation of malicious cyber attacks, the danger of permanent bounded cyber-attacks of ... [more ▼]

In this paper, the problem of permanent bounded cyber-attacks on networked control systems is treated. After a characterisation of malicious cyber attacks, the danger of permanent bounded cyber-attacks of two types is proved, the step attacks on system with invariant zero with zero real part and the free attacks. Simulation examples demonstrate the obtained results. [less ▲]

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See detailAn application of linear algebra theory in networked control systems: stochastic cyber-attacks detection approach
Li, Yumei UL; Voos, Holger UL; Darouach, Mohamed et al

in IMA Journal of Mathematical Control and Information (2015)

Based on the traditional linear algebra theory, this paper propose the attack detection schemes for networked control systems (NCSs) under single stochastic cyber-attack and multiple stochastic cyber ... [more ▼]

Based on the traditional linear algebra theory, this paper propose the attack detection schemes for networked control systems (NCSs) under single stochastic cyber-attack and multiple stochastic cyber-attacks aiming at multiple communication channels of NCSs, respectively. The focus is on designing an anomaly detector for NCSs under cyber-attacks. First, we construct a model of stochastic NCSs with stochastic cyber-attacks which satisfy the Markovian stochastic process. And we also introduced the stochastic attack models that NCSs are possibly exposed to. Next, based on the frequency-domain transformation technique and linear algebra theory, we propose the algebraic detection schemes for possible stochastic cyber-attacks. We transform the detector error dynamics into algebraic equations. By applying the presented approaches, residual information that is caused by different attacks is, respectively, obtained and anomalies on the control system are detected. In addition, sufficient and necessary conditions guaranteeing the detectability of the stochastic cyber-attacks are obtained. The presented detection approaches in this paper are simple, straightforward and easy to implement. The aim of this work is to use traditional mathematics tools to solve new problems that arise from the complex NCSs. Finally, two simulation examples are provided. The simulation results underline that the detection approaches are effective and feasible in practical application. [less ▲]

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See detailVision Based Fuzzy Control Autonomous Landing with UAVs: From V-REP to Real Experiments
Olivares Mendez, Miguel Angel UL; Kannan, Somasundar UL; Voos, Holger UL

in 23nd IEEE Mediterranean Conference of Control and Automation (MED), 2015, Torremolinos 2015, Spain (2015, June)

This paper is focused on the design of a vision based control approach for the autonomous landing task of Vertical Take-off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs). Here is presented the setup ... [more ▼]

This paper is focused on the design of a vision based control approach for the autonomous landing task of Vertical Take-off and Landing (VTOL) Unmanned Aerial Vehicles (UAVs). Here is presented the setup of a simulated environment developed in V-REP connected to ROS, and its uses for tuning a vision based control approach. In this work, a Fuzzy control approach was proposed to command the UAV’s vertical, longitudinal, lateral and orientation velocities. The UAV’s pose estimation was done based on a vision algorithm and the knowledge of the landing target. Real experiments with a quadrotor landing in a moving platform are also presented. [less ▲]

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See detailUncertainty Quantification of Exponential Synchronization for a Novel Class of Complex Dynamical Networks with Hybrid TVD Using PIPC
Pan, Lin UL; Voos, Holger UL; Li, Yumei UL et al

in Control and Decision Conference (CCDC), 2015 27th Chinese (2015, May 23)

Detailed reference viewed: 174 (21 UL)
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See detailStochastic cyber-attacks estimation for nonlinear control systems based on robust H∞ filtering technique
Yumei, Li UL; Voos, Holger UL; Pan, Lin UL et al

in Control and Decision Conference (CCDC), 2015 27th Chinese (2015, May 23)

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See detailAdaptive Control for the Methane Flow rate in Biogas Plants
Chaib Draa, Khadidja UL; Voos, Holger UL; Alma, Marouane et al

in 3rd IEEE Int. Conference on Control, Engineering and Information Technology, Tlemcen, Algeria, 2015 (2015, May)

In this paper we consider the control of the methane flow rate in biogas production using both a continuous stirred tank reactor and a fixed bed digester. The goal is to regulate the methane flow rate in ... [more ▼]

In this paper we consider the control of the methane flow rate in biogas production using both a continuous stirred tank reactor and a fixed bed digester. The goal is to regulate the methane flow rate in order to match an energy demand in spite of variations in the waste concentrations. For this purpose, a two step (acidogenesis-methanogenesis) nonlinear mass balance model is considered. Due to the costs and complexity of the measurements an adaptive observer is designed for the acidogenesis reaction rate. The stability of the observation part is proved and its implementation with the designed adaptive control law for the methane flow rate and the acetate concentration in the reactor are confirmed by simulations. [less ▲]

Detailed reference viewed: 184 (13 UL)