SwePub - sökning: WFRF:(Dimarogonas Dimos V.)

Numrering	Referens	Omslagsbild	Hitta
1.	Teixeira, Pedro V, et al. (författare) Event-based motion coordination of multiple underwater vehicles under disturbances 2010 Konferensbidrag (refereegranskat)abstract The problem of driving a formation from an initial to a target configuration while under the effect of external disturbances is studied. Additional restrictions on agent sensing as well as inter-agent communication must be satisfied. We present a leader-follower solution that relies on a simple uncertainty model to trigger surfacing events. These events are then used to update the control signal, for which two different, provably correct, control strategies are proposed. Finally, we show how the surfacing events can be used to characterize the disturbance set. Numerical examples on relevant scenarios are also provided.
2.	Teixeira, Pedro V., et al. (författare) Multi-agent coordination with event-based communication 2010 Ingår i: Proceedings of the American Control Conference. - : IEEE. - 9781424474264 ; , s. 824-829 Konferensbidrag (refereegranskat)abstract The problem of driving a set of vehicles (agents) to a desired target configuration under event-based communication and measurement constraints is analyzed. We start by studying the single agent problem, where we propose a waypoint based solution, along with two alternative control strategies. After deriving their properties and proving some relevant results, we proceed to study the two agent case. We generalize the results obtained for this network to the multi agent network. Our strategy is able to position each agent within a given distance of its target while satisfying the constraints. We provide some numerical examples for relevant scenarios.
3.	Adaldo, Antonio, 1989-, et al. (författare) Event-triggered pinning control of complex networks with switching topologies 2014 Ingår i: Proceedings of the 53rd annual IEEE Conference on Decision and Control. - 9781479977468 ; , s. 2783-2788 Konferensbidrag (refereegranskat)abstract This paper investigates the problem of eventtriggered pinning control for the synchronization of networks of nonlinear dynamical agents onto a desired reference trajectory. The pinned agents are those that have access to the reference trajectory. We consider both static and switching topologies. We prove that the system is well posed and identify conditions under which the network achieves exponential convergence. A lower bound for the rate of convergence is also derived. Numerical examples demonstrating the effectiveness of the results are provided.
4.	Anderson, R. P., et al. (författare) Self-triggered stabilization of continuous stochastic state-feedback controlled systems 2013 Ingår i: 2013 European Control Conference, ECC 2013. - : IEEE. - 9783033039629 ; , s. 1151-1155 Konferensbidrag (refereegranskat)abstract Event-triggered and self-triggered control, in which the time of update to the controls is based on either current or outdated sampled data, have recently been employed to reduce the computational load or resource consumption for distributed real-time control systems. In this work, we propose a self-triggered scheme for nonlinear controlled stochastic differential equations with additive noise terms. A self-triggering update condition is derived that guarantees stability in the p-th moment of the state distribution. We show that the length of the times between controller updates as computed from the proposed scheme is strictly positive and provide examples.
5.	Andreasson, Martin, 1987-, et al. (författare) Control of MTDC Transmission Systems under Local Information 2014 Ingår i: Decision and Control (CDC), 2014 IEEE 53rd Annual Conference on. - : IEEE conference proceedings. - 9781479977468 ; , s. 1335-1340 Konferensbidrag (refereegranskat)abstract High-voltage direct current (HVDC) is a commonly used technology for long-distance electric power transmission, mainly due to its low resistive losses. In this paper a distributed controller for multi-terminal high-voltage direct current (MTDC) transmission systems is considered. Sufficient conditions for when the proposed controller renders the closed-loop system asymptotically stable are provided. Provided that the closed loop system is asymptotically stable, it is shown that in steady-state a weighted average of the deviations from the nominal voltages is zero. Furthermore, a quadratic cost of the current injections is minimized asymptotically.
6.	Andreasson, Martin, et al. (författare) Distributed Control of Networked Dynamical Systems : Static Feedback, Integral Action and Consensus 2014 Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 59:7, s. 1750-1764 Tidskriftsartikel (refereegranskat)abstract This paper analyzes distributed control protocols for first- and second-order networked dynamical systems. We propose a class of nonlinear consensus controllers where the input of each agent can be written as a product of a nonlinear gain, and a sum of nonlinear interaction functions. By using integral Lyapunov functions, we prove the stability of the proposed control protocols, and explicitly characterize the equilibrium set. We also propose a distributed proportional-integral (PI) controller for networked dynamical systems. The PI controllers successfully attenuate constant disturbances in the network. We prove that agents with single-integrator dynamics are stable for any integral gain, and give an explicit tight upper bound on the integral gain for when the system is stable for agents with double-integrator dynamics. Throughout the paper we highlight some possible applications of the proposed controllers by realistic simulations of autonomous satellites, power systems and building temperature control.
7.	Andreasson, Martin, et al. (författare) Distributed integral action : stability analysis and frequency control of power systems 2012 Ingår i: 2012 IEEE 51st Annual Conference on Decision and Control (CDC). - : IEEE. - 9781467320665 ; , s. 2077-2083 Konferensbidrag (refereegranskat)abstract This paper analyzes distributed proportional-integral controllers. We prove that integral action can be successfully applied to consensus algorithms, where attenuation of static disturbances is achieved. These control algorithms are applied to decentralized frequency control of electrical power systems. We show that the proposed algorithm can attenuate step disturbances of power loads. We provide simulations of the proposed control algorithm on the IEEE 30 bus test system that demonstrate its efficiency.
8.	Andreasson, Martin, et al. (författare) Distributed PI-Control with Applications to Power Systems Frequency Control 2014 Ingår i: American Control Conference (ACC), 2014. - : IEEE conference proceedings. - 9781479932740 ; , s. 3183-3188 Konferensbidrag (refereegranskat)abstract This paper considers a distributed PI-controller for networked dynamical systems. Sufficient conditions for when the controller is able to stabilize a general linear system and eliminate static control errors are presented. The proposed controller is applied to frequency control of power transmission systems. Sufficient stability criteria are derived, and it is shown that the controller parameters can always be chosen so that the frequencies in the closed loop converge to nominal operational frequency. We show that the load sharing property of the generators is maintained, i.e., the input power of the generators is proportional to a controller parameter. The controller is evaluated by simulation on the IEEE 30 bus test network, where its effectiveness is demonstrated.
9.	Andreasson, Martin, 1987-, et al. (författare) Distributed Voltage and Current Control of Multi-Terminal High-Voltage Direct Current Transmission Systems 2014 Ingår i: Proceedings of the 19th IFAC World Congress, 2014. - : IFAC Papers Online. ; , s. 11910-11916 Konferensbidrag (refereegranskat)abstract High-voltage direct current (HVDC) is a commonly used technology for long-distance power transmission, due to its low resistive losses and low costs. In this paper, a novel distributed controller for multi-terminal HVDC (MTDC) systems is proposed. Under certain conditions on the controller gains, it is shown to stabilize the MTDC system. The controller is shown to always keep the voltages close to the nominal voltage, while assuring that the injected power is shared fairly among the converters. The theoretical results are validated by simulations, where the affect of communication time-delays is also studied.
10.	Andreasson, Martin, 1987-, et al. (författare) Distributed vs. centralized power systems frequency control 2013 Ingår i: 2013 European Control Conference, ECC 2013. - : IEEE. - 9783033039629 ; , s. 3524-3529 Konferensbidrag (refereegranskat)abstract This paper considers a distributed control algorithm for frequency control of electrical power systems. We propose a distributed controller which retains the reference frequency of the buses under unknown load changes, while asymptotically minimizing a quadratic cost of power generation. For comparison, we also propose a centralized controller which also retains the reference frequency while minimizing the same cost of power generation. We derive sufficient stability criteria for the parameters of both controllers. The controllers are evaluated by simulation on the IEEE 30 bus test network, where their performance is compared.
11.	Andreasson, Martin, 1987-, et al. (författare) Undamped Nonlinear Consensus Using Integral Lyapunov Functions 2012 Ingår i: 2012 American Control Conference (ACC). - : IEEE Computer Society. - 9781457710964 ; , s. 6644-6649 Konferensbidrag (refereegranskat)abstract This paper analyzes a class of nonlinear consensus algorithms where the input of an agent can be decoupled into a product of a gain function of the agents own state, and a sum of interaction functions of the relative states of its neighbors. We prove the stability of the protocol for both single and double integrator dynamics using novel Lyapunov functions, and provide explicit formulas for the consensus points. The results are demonstrated through simulations of a realistic example within the framework of our proposed consensus algorithm.
12.	Aragues, R., et al. (författare) Distributed algebraic connectivity estimation for adaptive event-triggered consensus 2012 Ingår i: American Control Conference (ACC), 2012. - : IEEE. - 9781457710957 ; , s. 32-37 Konferensbidrag (refereegranskat)abstract In several multi agent control problems, the convergence properties and speed of the system depend on the algebraic connectivity of the graph. We discuss a particular event-triggered consensus scenario, and show that the availability of an estimate of the algebraic connectivity could be used for adapting the behavior of the average consensus algorithm. We present a novel distributed algorithm for estimating the algebraic connectivity, that relies on the distributed computation of the powers of matrices. We provide proofs of convergence, convergence rate, and upper and lower bounds at each iteration of the estimated algebraic connectivity.
13.	Aragues, Rosario, et al. (författare) Distributed algebraic connectivity estimation for undirected graphs with upper and lower bounds 2014 Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 50:12, s. 3253-3259 Tidskriftsartikel (refereegranskat)abstract The algebraic connectivity of the graph Laplacian plays an essential role in various multi-agent control systems. In many cases a lower bound of this algebraic connectivity is necessary in order to achieve a certain performance. Lately, several methods based on distributed Power Iteration have been proposed for computing the algebraic connectivity of a symmetric Laplacian matrix. However, these methods cannot give any lower bound of the algebraic connectivity and their convergence rates are often unclear. In this paper, we present a distributed algorithm for estimating the algebraic connectivity for undirected graphs with symmetric Laplacian matrices. Our method relies on the distributed computation of the powers of the adjacency matrix and its main interest is that, at each iteration, agents obtain both upper and lower bounds for the true algebraic connectivity. Both bounds successively approach the true algebraic connectivity with the convergence speed no slower than O(1/k).
14.	Bechlioulis, C. P., et al. (författare) Robust control of large vehicular platoons with prescribed transient and steady state performance 2014 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - : IEEE conference proceedings. ; , s. 3689-3694 Konferensbidrag (refereegranskat)abstract In this paper, we consider the longitudinal control problem for a platoon of vehicles with unknown nonlinear dynamics. More specifically, we design a decentralized model-free control protocol in the sense that each vehicle utilizes only local relative information regarding its front vehicle, obtained by its on-board sensors, to calculate its own control signal, without incorporating any prior knowledge of the model nonlinearities/disturbances or any approximation structures to acquire such knowledge. Additionally, the transient and steady state response is a priori determined by certain designer-specified performance functions and is fully decoupled by the agents' dynamic model, the number of vehicles composing the platoon and the control gains selection, which relaxes significantly the control design procedure. Moreover, introducing certain inter-vehicular distance constraints during the transient response shaping, collisions between successive vehicles as well as connectivity breaks owing to limited sensing capabilities are provably avoided. Finally, the proposed methodology results in a low complexity design. Actually, it is a static scheme involving very few and simple calculations to output the control signal, thus making its distributed implementation straightforward.
15.	Borri, A., et al. (författare) Decentralized symbolic control of interconnected systems with application to vehicle platooning 2013 Ingår i: IFAC Proceedings Volumes. - 9783902823557 ; , s. 285-292 Konferensbidrag (refereegranskat)abstract This work aims at extending some concepts of symbolic control design to decentralized control structures, with an approximate simulation approach. Symbolic models and controllers are based on abstractions of continuous dynamics where one symbol corresponds to an aggregate of continuous states. We consider a serial interconnection of continuous nonlinear systems and we address the decentralized design of local controllers to accomplish a given specification on the overall system. The results are applied to a vehicle platooning problem, where we jointly fulfill a safety constraint (collision avoidance) and reduce the fuel consumption.
16.	Colledanchise, Michele, 1987-, et al. (författare) Robot navigation under uncertainties using event based sampling 2014 Ingår i: Decision and Control (CDC), 2014 IEEE 53rd Annual Conference on. - : IEEE conference proceedings. ; , s. 1438-1445 Konferensbidrag (refereegranskat)abstract In many robot applications, sensor feedback is needed to reduce uncertainties in environment models. However, sensor data acquisition also induces costs in terms of the time elapsed to make the observations and the computations needed to find new estimates. In this paper, we show how to use event based sampling to reduce the number of measurements done, thereby saving time, computational resources and power, without jeopardizing critical system properties such as safety and goal convergence. This is done by combining recent advances in nonlinear estimation with event based control using artificial potential fields. The results are particularly useful for real time systems such as high speed vehicles or teleoperated robots, where the cost of taking measurements is even higher, in terms of stops or transmission times. We conclude the paper with a set of simulations to illustrate the effectiveness of the approach and compare it with a baseline approach using periodic measurements.
17.	Dimarogonas, Dimos V., et al. (författare) Bounded control of network connectivity in multi-agent systems 2010 Ingår i: IET Control Theory & Applications. - : Institution of Engineering and Technology (IET). - 1751-8644 .- 1751-8652. ; 4:8, s. 1330-1338 Tidskriftsartikel (refereegranskat)abstract A distributed control law that guarantees connectivity maintenance in a network of multiple mobile agents is presented. The control law, which lets the agents perform formation manoeuvres, respects sensor limitations by allowing each agent to only take into account agents within its sensing radius. In contrast to previous approaches to the problem, the proposed control law does not attain infinite values whenever an edge of the communication graph tends to be lost. This is achieved via the use of decentralised navigation functions, which are bounded potential fields. The navigation functions are defined to take into account the connectivity maintenance objective. The authors first treat the case of connectivity maintenance for a static communication graph and then extend the result to the case of dynamic graphs. The results are illustrated on a formation control problem.
18.	Dimarogonas, Dimos V., et al. (författare) Distributed Event-Triggered Control for Multi-Agent Systems 2012 Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 57:5, s. 1291-1297 Tidskriftsartikel (refereegranskat)abstract Event-driven strategies for multi-agent systems are motivated by the future use of embedded microprocessors with limited resources that will gather information and actuate the individual agent controller updates. The controller updates considered here are event-driven, depending on the ratio of a certain measurement error with respect to the norm of a function of the state, and are applied to a first order agreement problem. A centralized formulation is considered first and then its distributed counterpart, in which agents require knowledge only of their neighbors' states for the controller implementation. The results are then extended to a self-triggered setup, where each agent computes its next update time at the previous one, without having to keep track of the state error that triggers the actuation between two consecutive update instants. The results are illustrated through simulation examples.
19.	Dimarogonas, Dimos V., et al. (författare) Distributed self-triggered control for multi-agent systems 2010 Konferensbidrag (refereegranskat)abstract It is desirable to limit the amount of communication and computation generated by each agent in a large multi-agent system. Event- and self-triggered control strategies have been recently proposed as alternatives to traditional time-triggered periodic sampling for feedback control systems. In this paper we consider self-triggered control applied to a multi-agent system with an agreement objective. Each agent computes its next update time instance at the previous time. This formulation extends considerably our recent work on event-based control, because in the self-triggered setting the agents do not have to keep track of the state error that triggers the actuation between consecutive update instants. Both a centralized and a distributed self-triggered control architecture are presented and shown to achieve the agreement objective. The results are illustrated through simulated examples.
20.	Dimarogonas, Dimos V. (författare) L2 Gain Stability Analysis of Event-triggered Agreement Protocols 2011 Ingår i: 50th IEEE Conference of Decision and Control (CDC)/European Control Conference (CDC-ECC). ; , s. 2130-2135 Konferensbidrag (refereegranskat)abstract We extend our previous results on event-triggered agreement by proposing a triggering mechanism that is finite L-2 gain stable with respect to additive disturbances in the open loop dynamics of the agents. Moreover, the control design is both distributed and provides strictly positive inter-execution times. Simulation examples support the derived theoretical results
21.	Dimarogonas, Dimos V., et al. (författare) Stability analysis for multi-agent systems using the incidence matrix : Quantized communication and formation control 2010 Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 46:4, s. 695-700 Tidskriftsartikel (refereegranskat)abstract The spectral properties of the incidence matrix of the communication graph are exploited to provide solutions to two multi-agent control problems. In particular, we consider the problem of state agreement with quantized communication and the problem of distance-based formation control. In both cases, stabilizing control laws are provided when the communication graph is a tree. It is shown how the relation between tree graphs and the null space of the corresponding incidence matrix encode fundamental properties for these two multi-agent control problems.
22.	Dimarogonas, Dimos V. (författare) Sufficient Conditions for Decentralized Navigation Functions Based Controllers using Canonical Vector Fields 2011 Ingår i: 2011 50TH IEEE CONFERENCE ON DECISION AND CONTROL AND EUROPEAN CONTROL CONFERENCE (CDC-ECC). - 9781612848013 ; , s. 6433-6438 Konferensbidrag (refereegranskat)abstract A combination of dual Lyapunov analysis and properties of decentralized navigation function based controllers is used to check the stability properties of a certain class of decentralized controllers for navigation and collision avoidance in multi-agent systems. The derived results yield a less conservative condition from previous approaches, which relates to the negativity of the sum of the minimum eigenvalues of the Hessian matrices at the critical points, instead of requiring each of the eigenvalues to be negative itself. This provides an improved characterization of the reachable set of this class of decentralized navigation function based controllers, which is less conservative than the previous results for the same class of controllers.
23.	Dimarogonas, Dimos V. (författare) Sufficient Conditions for Decentralized Potential Functions Based Controllers Using Canonical Vector Fields 2012 Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 57:10, s. 2621-2626 Tidskriftsartikel (refereegranskat)abstract A combination of dual Lyapunov analysis and properties of decentralized navigation function based controllers is used to check the stability properties of a certain class of decentralized controllers for navigation and collision avoidance in multiagent systems. The derived results yield a less conservative condition from previous approaches, which relates to the negativity of the sum of the minimum eigenvalues of the Hessian matrices at the critical points, instead of requiring each of the eigenvalues to be negative itself. This provides an improved characterization of the reachable set of this class of decentralized navigation function based controllers, which is less conservative than the previous results for the same class of controllers.
24.	Durr, H. -B, et al. (författare) Obstacle avoidance for an extremum seeking system using a navigation function 2013 Ingår i: Proceedings of the American Control Conference 2013. - : AACC American Automatic Control Council. - 9781479901777 ; , s. 4062-4067 Konferensbidrag (refereegranskat)abstract The problem of autonomously steering a vehicle to a destination point, while avoiding obstacles, is considered. The vehicle is modeled as a single-integrator in the plane and it is assumed that the obstacles are unknown a priori. The control law is an extremum seeking algorithm, which steers the vehicle to the minimum of a navigation function. In this framework, obstacle avoidance and practical uniform convergence to a destination point for almost all initial conditions is proven. The theoretic results are illustrated using numerical examples.
25.	Eqtami, A., et al. (författare) Aperiodic model predictive control via perturbation analysis 2012 Ingår i: Decision and Control (CDC), 2012 IEEE 51st Annual Conference on. - : IEEE. ; , s. 7193-7198 Konferensbidrag (refereegranskat)abstract In this paper, an enhanced event-based scheme for model predictive control (MPC) of constrained discrete-time systems with additive disturbances is investigated. The re/calculation of the MPC control law is triggered whenever an event depending on the error of the measured state with respect to the nominal state of the system occurs. Between the controller updates, the last computed control trajectory is applied to the system, in conjunction with a correction term. This term consists of a perturbation solution of the nominal system which itself depends on the aforementioned error. The overall framework yields less conservative results with respect to our previous work. The results are illustrated through a simulated example.
26.	Eqtami, A., et al. (författare) Event-based model Predictive control for the cooperation of distributed agents 2012 Ingår i: 2012 American Control Conference (ACC). - : IEEE Computer Society. - 9781457710957 ; , s. 6473-6478 Konferensbidrag (refereegranskat)abstract This paper proposes an event-based framework for the control of a team of cooperating distributed agents. The agents are dynamically decoupled and they are controlled locally by Nonlinear Model Predictive Controllers (NMPC). The event-driven framework allows for triggering the solution of the optimal control problem of the NMPC only when it is needed. The scheduling of the control updates for each of the agents depends on an error of the state information received from the neighboring agents. Sufficient conditions for triggering are provided and the results are illustrated through a simulated example.
27.	Eqtami, Alina, et al. (författare) Event-Triggered Strategies for Decentralized Model Predictive Controllers 2011 Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). Konferensbidrag (refereegranskat)abstract In this paper, novel event-triggered strategies for the design of model predictive (MPC) controllers are presented. The MPC framework consists in finding the solution to a constraint optimal-control problem at every time-step. The case of triggering the optimization of the MPC only when is needed, is investigated. The centralized case is treated first and the results are then extended to a decentralized formulation. We consider a system composed by a number of interconnected subsystems, each one of them controlled by a robust MPC algorithm. Using the Input-to-State (ISS) property of the decentralized MPC controller we reach to an event-triggering rule, for each of the subsystems
28.	Eqtami, Alina, et al. (författare) Novel Event-Triggered Strategies for Model Predictive Controllers 2011 Ingår i: 2011 50TH IEEE CONFERENCE ON DECISION AND CONTROL AND EUROPEAN CONTROL CONFERENCE (CDC-ECC). ; , s. 3392-3397 Konferensbidrag (refereegranskat)abstract This paper proposes novel event-triggered strategies for the control of uncertain nonlinear systems with additive disturbances under robust Nonlinear Model Predictive Controllers (NMPC). The main idea behind the event-driven framework is to trigger the solution of the optimal control problem of the NMPC, only when it is needed. The updates of the control law depend on the error of the actual and the predicted trajectory of the system. Sufficient conditions for triggering are provided for both, continuous and discrete-time nonlinear systems. The closed-loop system evolves to a compact set where it is ultimately bounded, under the proposed framework. The results are illustrated through a simulated example.
29.	Eqtami, A., et al. (författare) Self-triggered model predictive control for nonholonomic systems 2013 Ingår i: 2013 European Control Conference, ECC 2013. - : IEEE. - 9783033039629 ; , s. 638-643 Konferensbidrag (refereegranskat)abstract This paper proposes a Model Predictive Control (MPC) framework combined with a self-triggering mechanism for constrained uncertain systems. Under the proposed scheme, the control input as well as the next control update time are provided at each triggering instant. Between two consecutive triggering instants, the control trajectory given by the MPC is applied to the plant in an open-loop fashion. This results to less frequent computations while preserving stability and convergence of the closed-loop system. A scenario for the stabilization of a nonholonomic robot subject to constraints and disturbances is considered, with the aim of reaching a specific triggering mechanism. The robot under the proposed control framework is driven to a compact set where it is ultimately bounded. The efficiency of the proposed approach is illustrated through a simulated example.
30.	Eqtami, A., et al. (författare) Self-triggered model predictive control framework for the cooperation of distributed nonholonomic agents 2013 Ingår i: 2013 IEEE 52nd Annual Conference on Decision and Control (CDC). - : IEEE conference proceedings. - 9781467357173 ; , s. 7384-7389 Konferensbidrag (refereegranskat)abstract In this paper we propose a decentralized Model Predictive Control (MPC) framework with a self-triggering mechanism, for a team of cooperating agents. The nonholonomic agents are controlled locally and exchange information with their neighbors. The aim at scheduling the control updates based on a self-triggering criterion is twofold: To reduce the updates of the control law for each agent and to reduce the communication effort between the agents. The input-to-state (abbr. ISS) stability of the agents is proven, the condition for triggering is provided and the theoretic results are then depicted by a simulated example.
31.	Filippidis, I., et al. (författare) Decentralized multi-agent control from local LTL specifications 2012 Ingår i: Decision and Control (CDC), 2012 IEEE 51st Annual Conference on. - : IEEE. ; , s. 6235-6240 Konferensbidrag (refereegranskat)abstract We propose a methodology for decentralized multi-agent control from Linear Temporal Logic (LTL) specifications. Each agent receives an independent specification to formally synthesize its own hybrid controller. Mutual satisfiability is not a priori guaranteed. Due to limited communication, the agents utilize meeting events to exchange their controller automata and verify satisfiability through model checking. Local interaction only when common atomic propositions exist reduces the overall computational cost, facilitating scalability. Provably correct collision avoidance and convergence is ensured by Decentralized Multi-Agent Navigation Functions.
32.	Giannis, Roussos, et al. (författare) 3D Navigation and Collision Avoidance for Nonholonomic aircraft-like vehicles 2010 Ingår i: International journal of adaptive control and signal processing (Print). - : Wiley. - 0890-6327 .- 1099-1115. ; 24:10, s. 900-920 Tidskriftsartikel (refereegranskat)abstract This paper extends the Navigation Function methodology to the case of 3D nonholonomic vehicles, both in single agent and multi-agent problems. The kinematic, nonholonomic, three-dimensional model considered is chosen to resemble the motion of an aircraft by preventing any movement along the lateral or perpendicular axis, as well as preventing high yaw rotation rates. The discontinuous feedback control law used is based on the artificial potential field generated by Dipolar Navigation Functions and steers the agents away from obstacles or each other and towards their destinations, while respecting the nonholonomic constraints present. The convergence properties of the proposed control strategies are formally guaranteed and verified by non-trivial simulation results
33.	Guinaldo, M., et al. (författare) Distributed event-based control for interconnected linear systems 2011 Ingår i: 2011 50th IEEE Conference on Decision and Control andEuropean Control Conference (CDC-ECC). ; , s. 2553-2558 Konferensbidrag (refereegranskat)abstract This paper presents a distributed event-basedcontrol strategy for a networked dynamical system consistingof N linear time-invariant interconnected subsystems. Eachsubsystem broadcasts its state over the network accordingto some triggering rules which depend on local informationonly. The system converges to an adjustable region aroundthe equilibrium point under the proposed control design, andthe existence of a lower bound for the broadcasting period isguaranteed. The effect of the coupling terms over the region ofconvergence and broadcasting period lower bound is analyzed,and a novel model-based approach is derived to reduce thecommunications. Simulation results show the effectiveness ofthe proposed approaches and illustrate the theoretical results.
34.	Guinaldo, Maria, et al. (författare) Distributed event-based control strategies for interconnected linear systems 2013 Ingår i: IET Control Theory & Applications. - : Institution of Engineering and Technology (IET). - 1751-8644 .- 1751-8652. ; 7:6, s. 877-886 Tidskriftsartikel (refereegranskat)abstract This study presents distributed event-based control strategies for a networked dynamical system consisting of N linear time-invariant interconnected subsystems. Each subsystem broadcasts its state over the network according to certain triggering rules that only depend on local information. The system can converge asymptotically to the equilibrium point under the proposed control design, and the existence of a lower bound for the broadcasting period is guaranteed. A novel model-based approach is derived to reduce the communication between the agents. Simulation results show the effectiveness of the proposed approaches and illustrate the theoretical results.
35.	Guo, Meng, et al. (författare) Consensus with quantized relative state measurements 2013 Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 49:8, s. 2531-2537 Tidskriftsartikel (refereegranskat)abstract In this paper, cooperative control of multi-agent systems under limited communication between neighboring agents is investigated. In particular, quantized values of the relative states are used as the control parameters. By taking advantage of tools from nonsmooth analysis, explicit convergence results are derived for both uniform and logarithmic quantizers under static and time-varying communication topologies. Compared with our previous work, less conservative conditions that ensure global convergence are provided. Moreover, second order dynamical systems under similar constraints are taken into account. Computer simulations are provided to demonstrate the validity of the derived results.
36.	Guo, Meng, et al. (författare) Controlling the Relative Agent Motion in Multi-Agent Formation Stabilization 2014 Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 59:3, s. 820-826 Tidskriftsartikel (refereegranskat)abstract In this technical note, we propose a novel technique to control the relative motion of multiple mobile agents as they stabilize to a desired configuration. In particular, we focus on the agents' relative velocities and the rate of change of their pairwise distances, and employ constructs from classic navigation functions (NFs) to control these quantities. Controlling agent velocities requires nontrivial extensions of the NF methodology to second-order models. Although in this work we propose a centralized framework to control the relative agent velocities, it adds a new dimension to the control of multi-agent systems with several advantages. In particular, we provide a novel approach to control the transient dynamics of a network that may facilitate the integration of continuous motion planing with discrete topology control. The result is verified theoretically and via computer simulations.
37.	Guo, Meng, et al. (författare) Cooperative decentralized multi-agent control under local LTL tasks and connectivity constraints 2014 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - : IEEE conference proceedings. ; , s. 75-80 Konferensbidrag (refereegranskat)abstract We propose a framework for the decentralized control of a team of agents that are assigned local tasks expressed as Linear Temporal Logic (LTL) formulas. Each local LTL task specification captures both the requirements on the respective agent's behavior and the requests for the other agents' collaborations needed to accomplish the task. Furthermore, the agents are subject to communication constraints. The presented solution follows the automata-theoretic approach to LTL model checking, however, it avoids the computationally demanding construction of synchronized product system between the agents. A decentralized coordination scheme through a dynamic leader selection is proposed, to guarantee the low-level connectivity maintenance and a progress towards the satisfaction of each agent's task.
38.	Guo, Meng, 1988- (författare) Cooperative Motion and Task Planning Under Temporal Tasks 2014 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Temporal-logic-based languages provide a formal and accurate way to specify complex motion and action missions for autonomous robots, beyond the classic point-to-point navigation task. The first part of the thesis is devoted to the nominal scenario: an autonomous robot is given a motion task specified as Linear-time Temporal Logic (LTL) formulas. Under the assumption that the workspace is static and fully-known, we provide a systematic and automated scheme to synthesize both the discrete motion and task plan and the hybrid control strategy that drives the robot, such that the resulting trajectory fulfills the given task specification. Limited knowledge about the workspace model, unforeseen changes in the workspace property and un-modeled dynamical constraints of the robot may render the nominal approach inadequate. Thus in the second part of the thesis we take into account four non-nominal scenarios where: (i) the specified task is not feasible; (ii) the task contains hard and soft constraints; (iii) the workspace model is not fully-known in priori; (iv) the task involves not only robot motion but also actions. The proposed results greatly improve the real-time adaptability and reconfigurability of the nominal scheme. In the last part, we analyze a team of interconnected autonomous robots with local and independently-assigned tasks. Firstly we consider the case where cooperations among the robots are imposed due to heterogeneity and collaborative tasks. A decentralized coordination scheme is proposed such that the robots' joined plans satisfy their mutual tasks the most. Then a distributed knowledge transfer and update procedure is designed for the networked robots that co-exist within a common but partially-known workspace. It guarantees both the safety and correctness of their individual plans.
39.	Guo, Meng, et al. (författare) Distributed plan reconfiguration via knowledge transfer in multi-agent systems under local LTL specifications 2014 Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. ; , s. 4304-4309 Konferensbidrag (refereegranskat)abstract We propose a cooperative motion and task planning scheme for multi-agent systems where the agents have independently-assigned local tasks, specified as Linear Temporal Logic (LTL) formulas. These tasks contain hard and soft sub-specifications. A least-violating initial plan is synthesized first for the potentially infeasible task and the partially-known workspace. While the system runs, each agent updates its knowledge about the workspace via its sensing capability and shares this knowledge with its neighboring agents. Based on this update, each agent verifies and revises its plan in real time. It is ensured that the hard specification is always fulfilled and the satisfaction for the soft specification is improved gradually. The design is distributed as only local interactions are assumed. The overall framework is demonstrated by a case study.
40.	Guo, Meng, et al. (författare) Distributed real-time fault detection and isolation for cooperative multi-agent systems 2012 Ingår i: 2012 American Control Conference (ACC). - : IEEE Computer Society. - 9781457710957 ; , s. 5270-5275 Konferensbidrag (refereegranskat)abstract In this paper we propose a distributed real-time fault detection, isolation and mitigation framework for multiagent systems performing cooperative tasks. Various system models and detection schemes with respect to communication and sensing are considered. Two communication protocols for fault detection are introduced first and proved to be effective. Then a scheme based on limited relative state measurements is developed. Furthermore, we propose fault isolation and mitigation steps to guarantee the accomplishment of a global objective. All schemes are distributed in the sense that at each step of the fault detection, isolation and mitigation every agent only uses locally available information. One key feature of the framework is the significant reduction of required computational resource when compared with the fault detection and isolation schemes based on unknown input observers. Later we show that the proposed framework can be applied to the consensus and other cooperative formation problems. Several computer simulations are presented to demonstrate the efficiency of the framework.
41.	Guo, Meng, et al. (författare) Motion and Action Planning under LTL Specifications using Navigation Functions and Action Description Language 2013 Ingår i: 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). - : IEEE. - 9781467363587 ; , s. 240-245 Konferensbidrag (refereegranskat)abstract We propose a novel framework to combine model-checking-based motion planning with action planning using action description languages, aiming to tackle task specifications given as Linear Temporal Logic (LTL) formulas. The specifications implicitly require both sequential regions to visit and the desired actions to perform at these regions. The robot's motion is abstracted based on sphere regions of interest in the workspace and the structure of navigation function(NF)-based controllers, while the robot's action map is constructed based on precondition and effect functions associated with the actions. An optimal planner is designed that generates the discrete motion-and-action plan fulfilling the specification, as well as the low-level hybrid controllers that implement this plan. The whole framework is demonstrated by a case study.
42.	Guo, Meng, 1988-, et al. (författare) Nonlinear consensus via continuous, sampled, and aperiodic updates 2013 Ingår i: International Journal of Control. - : Taylor & Francis. - 0020-7179 .- 1366-5820. ; 86:4, s. 567-578 Tidskriftsartikel (refereegranskat)abstract We consider a first-order multi-agent system with nonlinear control protocols performing consensus. We first address the convergence properties of the continuous system. Then periodically sampled control inputs are treated, where we derive explicit upper bounds on the sampling interval to preserve global stability. Moreover, we design an aperiodic and event-triggered updating law to reduce the control efforts even further while ensuring the closed-loop stability and providing a strictly positive lower bound on the inter-execution time. Finally, the robustness of this approach with respect to additive disturbances is examined by applying L-2 gain analysis.
43.	Guo, Meng, et al. (författare) Quantized cooperative control using relative state measurements 2011 Ingår i: 2011 50th IEEE Conference on Decision and Control and European Control Conference. ; , s. 5601-5606 Konferensbidrag (refereegranskat)abstract We consider cooperative control of multi-agent systems under limited communication between neighboring agents. In particular, quantized values of the relatives states are used as the control parameters of each agent. The results are derived for both uniform and logarithmic quantizers. Both static and time-varying communication topologies are considered. The stability conditions derived are less conservative than the corresponding ones in our previous work. Moreover, the case of second order dynamics is taken into account. The derived results are supported through computer simulations
44.	Guo, Meng, et al. (författare) Reconfiguration in motion planning of single- And multi-agent systems under infeasible local LTL specifications 2013 Ingår i: 2013 IEEE 52nd Annual Conference on Decision and Control (CDC). - : IEEE conference proceedings. - 9781467357142 ; , s. 2758-2763 Konferensbidrag (refereegranskat)abstract A reconfiguration method for the model-checkingbased motion planning of single- And multi-agent systems under infeasible local LTL specifications is proposed. The method describes how to synthesize the motion plan that fulfills the infeasible task specification the most, and how the infeasible task specification is relaxed. The novelty is the introduction of a metric within the atomic proposition domain, and the relative weighting between the implementation cost of a motion plan and its distance to the original specification. For multiagent systems, a dependency relation and relative priorities are incorporated when the tasks are assigned independently to each agent. Simulations are presented to illustrate the method.
45.	Guo, Meng, et al. (författare) Revising motion planning under Linear Temporal Logic specifications in partially known workspaces 2013 Ingår i: 2013 IEEE International Conference on Robotics and Automation (ICRA). - : IEEE Computer Society. - 9781467356411 - 9781467356435 ; , s. 5025-5032 Konferensbidrag (refereegranskat)abstract In this paper we propose a generic framework for real-time motion planning based on model-checking and revision. The task specification is given as a Linear Temporal Logic formula over a finite abstraction of the robot motion. A preliminary motion plan is first generated based on the initial knowledge of the system model. Then real-time information obtained during the runtime is used to update the system model, verify and further revise the motion plan. The implementation and revision of the motion plan are performed in real-time. This framework can be applied to partially-known workspaces and workspaces with large uncertainties. Computer simulations are presented to demonstrate the efficiency of the framework.
46.	Gustavi, Tove, et al. (författare) Sufficient conditions for connectivity maintenance and rendezvous in leader-follower networks 2010 Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 46:1, s. 133-139 Tidskriftsartikel (refereegranskat)abstract In this paper we derive a set of constraints that are sufficient to guarantee maintained connectivity in a leader-follower multi-agent network with proximity based communication topology. In the scenario we consider, only the leaders are aware of the global mission, which is to converge to a known destination point. Thus, the followers need to stay in contact with the group of leaders in order to reach the goal. In the paper we show that we can maintain the initial network structure, and thereby connectivity, by setting up bounds on the ratio of leaders-to-followers and on the magnitude of the goal attraction force experienced by the leaders. The results are first established for an initially complete communication graph and then extended to an incomplete graph. The results are illustrated by computer simulations.
47.	Heshmati-Alamdari, S., et al. (författare) A self-triggered visual servoing model predictive control scheme for under-actuated underwater robotic vehicles 2014 Ingår i: Proceedings - IEEE International Conference on Robotics and Automation. - : IEEE conference proceedings. ; , s. 3826-3831 Konferensbidrag (refereegranskat)abstract This paper presents a novel Vision-based Nonlinear Model Predictive Control (NMPC) scheme for an under-actuated underwater robotic vehicle. In this scheme, the control loop does not close periodically, but instead a self-triggering framework decides when to provide the next control update. Between two consecutive triggering instants, the control sequence computed by the NMPC is applied to the system in an open-loop fashion, i.e, no state measurements are required during that period. This results to a significant smaller number of requested measurements from the vision system, as well as less frequent computations of the control law, reducing in that way the processing time and the energy consumption. The image constraints (i.e preserving the target inside the camera's field of view), the external disturbances induced by currents and waves, as well as the vehicle's kinematic constraints due to under-actuation, are being considered during the control design. The closed-loop system has analytically guaranteed stability and convergence properties, while the performance of the proposed control scheme is experimentally verified using a small under-actuated underwater vehicle in a test tank.
48.	Katsilieris, Fotios, et al. (författare) Demonstration of multi-robot search and secure 2010 Konferensbidrag (refereegranskat)abstract We consider the search and secure problem, where intruders are to be detected in a bounded area without allowing them to escape. The problem is tackled by representing the area to be searched as a traversability graph, which is reduced to a tree graph by placing stationary robots to remove loops. The search of the remaining tree is performed using two strategies that represent different trade-offs between the needed search time and the number of robots. Proof of correctness is provided for these two strategies. The proposed algorithm was implemented and demonstrated as part of an outfield experiment involving a team of Rotundus spherical robots.
49.	Larsson, Martin, et al. (författare) Towards an Indoor Testbed for Mobile Networked Control Systems 2011 Konferensbidrag (refereegranskat)abstract In this paper, we consider the design of an indoor testbed composed of multiple aerial and ground unmanned vehicles for experimentation in Mobile Networked Control Systems. Taking several motivational aspects from both research and education into account, we propose an architecture to cope with the scale and mobility aspects of the overall system. Currently, the testbed is composed of several low-cost ARdrones quadrotors, small-scale heavy duty vehicles, wireless sensor nodes and a vision-based localization system. As an example, the automatic control of an ARdrone is shown.
50.	Liuzza, D., et al. (författare) Distributed model based event-triggered control for synchronization of multi-agent systems 2013 Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - 9783902823472 ; , s. 329-334 Konferensbidrag (refereegranskat)abstract This paper investigates the problem of event-based control for the synchronization of networks of nonlinear dynamical agents. A distributed model based approach able to guarantee that all the agents converge to an adjustable synchronization region is derived. In such control scheme all the agents use a model of their neighborhood in order to generate triggering instants in which the local controller is updated and, if needed, local information is broadcasted to neighboring agents. The existence of a minimum lower bound between inter-event times is proven both for broadcasted information as well as for control signal updating, thus allowing implementation of the proposed strategy in applications where both the communication bandwidth and the maximum updating frequency of actuators are critical.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "WFRF:(Dimarogonas Dimos V.) srt2:(2010-2014)"

Avgränsa träffmängd

År