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  • 51.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Decentralized connectivity maintenance in mobile networks with bounded inputs2008Inngår i: 2008 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, 2008, s. 1507-1512Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A distributed control law that guarantees connectivity maintenance in a network of multiple mobile agents is presented. The control law respects the limited sensing capabilities of the agents by allowing each agent to take into account only agents within its sensing radius in the controller implementation. In contrast to previous approaches to the problem, the proposed control law does not attain infinite values whenever an edge tends to be lost, and is therefore a bounded distributed control law. This is achieved via the use of decentralized navigation functions which are potential fields with guaranteed boundedness and are redefined in this paper in order to take into account the connectivity maintenance objective. We first treat the case of connectivity maintenance in a static initial position based communication graph and extend the results to the case of dynamic edge addition. The results are then applied to a formation control problem.

  • 52.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Event-triggered control for multi-agent systems2009Inngår i: Proceedings of the IEEE Conference on Decision and Control, 2009, s. 7131-7136Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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 control actuation updates considered in this paper 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 of the problem is considered first and then the results are extended to the decentralized counterpart, in which agents require knowledge only of the states of their neighbors for the controller implementation.

  • 53.
    Dimarogonas, Dimos V.
    et al.
    Massachusetts Institute of Technology, United States.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Event-triggered cooperative control2015Inngår i: 2009 European Control Conference, ECC 2009, IEEE Press, 2015, s. 3015-3020Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Future multi-agent systems will include embedded microprocessors with limited resources to gather information and actuate the individual agent controller updates. In this paper we examine the stability of such scheme in a cooperative control problem where the actuation updates are event-driven, depending on the ratio of a certain measurement error with respect to the norm of the state. In the centralized case, we obtain a strictly positive lower bound in the inter-event times, while relevant, yet more conservative, results are obtained in the decentralized case.

  • 54.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Further results on the stability of distance-based multi-robot formations2009Inngår i: 2009 AMERICAN CONTROL CONFERENCE, VOLS 1-9, 2009, s. 2972-2977Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An important class of multi-robot formations is specified by desired distances between adjacent robots. In previous work, we showed that distance-based formations can be globally stabilized by negative gradient, potential field based, control laws, if and only if the formation graph is a tree. In this paper, we further examine the relation between the cycle space of the formation graph and the resulting equilibria of cyclic formations. In addition, the results are extended to the case of distance based formation control for nonholonomic agents. The results are supported through computer simulations.

  • 55.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    On the stability of distance-based formation control2008Inngår i: Proceedings of the IEEE Conference on Decision and Control, 2008, s. 1200-1205Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper examines stability properties of distance-based formations. These are formations encoded by inter-agent relative distances. A negative gradient control law is proposed and is shown to be provably correct when the formation graph is a tree. Moreover, it is shown that the tree structure is a necessary and sufficient condition for distancebased formation stabilization with negative gradient control laws. For graphs that contain cycles, a characterization of the resulting equilibria is given based on the properties of the cycle space of the graph. The results are also applied to flocking motion for double integrator agents.

  • 56.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Quantized agreement under time-varying communication topology2008Inngår i: 2008 AMERICAN CONTROL CONFERENCE, 2008, s. 4376-4381Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Cooperative control under quantized information for multi-agent systems with continuous models of motion is considered. Time-varying communication topology is taken into account and we distinguish between uniform and logarithmic quantization. Convergence guarantees are provided when the graph is a tree sufficiently often for the logarithmic quantizer, using tools from algebraic graph theory and Lyapunov stability. The results are illustrated by computer simulations.

  • 57.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, K. J.
    A connection between formation infeasibility and velocity alignment in kinematic multi-agent systems2008Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 44, nr 10, s. 2648-2654Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, a feedback control strategy that achieves convergence of a multi-agent system to a desired formation configuration is proposed for both the cases of agents with single integrator and nonholonomic unicycle-type kinematics. When inter-agent objectives that specify the desired formation cannot occur simultaneously in the state space the desired formation is infeasible. it is shown that under certain assumptions, formation infeasibility forces the agents' velocity vectors to a common value at steady state. This provides a connection between formation infeasibility and flocking behavior for the multi-agent system. We finally also obtain an analytic expression of the common velocity vector in the case of formation infeasibility.

  • 58.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kyriakopoulos, K. J.
    Connectedness Preserving Distributed Swarm Aggregation for Multiple Kinematic Robots2008Inngår i: IEEE Transactions on robotics, ISSN 1552-3098, E-ISSN 1941-0468, Vol. 24, nr 5, s. 1213-1223Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A distributed swarm aggregation algorithm is developed for a team of multiple kinematic agents. Specifically, each agent is assigned a control law, which is the sum of two elements: a repulsive potential field, which is responsible for the collision avoidance objective, and an attractive potential field, which forces the agents to converge to a configuration where they are close to each other. Furthermore, the attractive potential field forces the agents that are initially located within the sensing radius of an agent to remain within this area for all time. In this way, the connectivity properties of the initially formed communication graph are rendered invariant for the trajectories of the closed-loop system. It is shown that under the proposed control law, agents converge to a configuration where each agent is located at a bounded distance from each of its neighbors. The results are also extended to the case of nonholonomic kinematic unicycle-type agents and to the case of dynamic edge addition. In the latter case, we derive a smaller bound in the swarm size than in the static case.

  • 59.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kyriakopoulos, K. J.
    Inverse Agreement Protocols With Application to Distributed Multi-Agent Dispersion2009Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 54, nr 3, s. 657-663Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose a distributed inverse agreement control law for multiple kinematic agents that forces the team members to disperse In the workspace. Both the cases of an unbounded and a circular, bounded workspace are considered. In the first case, we show that the closed-loop system reaches a configuration In which the minimum distance between any pair of agents is larger than a specific lower bound. It is proved that this lower bound coincides with the agents' sensing radius. In the case of a bounded circular workspace, the control law is redefined to force the agents to remain within the workspace boundary. Moreover the proposed control design guarantees collision avoidance between the team members in all cases. The results are supported through relevant computer simulations.

  • 60.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, Kostas J.
    An inverse agreement control strategy with application to swarm dispersion2007Inngår i: PROCEEDINGS OF THE 46TH IEEE CONFERENCE ON DECISION AND CONTROL, 2007, s. 3824-3829Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose an inverse agreement control strategy for multiple kinematic agents that forces the team members to disperse in the workspace in a distributed manner. Both the cases of an unbounded and a cyclic, bounded workspace are considered. In the first case, we show that the closed loop system reaches a configuration in which the minimum distance between any pair of agents is larger than a specific lower bound. It is proved that this lower bound coincides with the agents' sensing radius. In the case of a bounded cyclic workspace, the control law is redefined in order to force the agents to remain within the workspace boundary throughout the closed loop system evolution. Moreover the proposed control design guarantees collision avoidance between the team members in both cases. The results are supported through relevant computer simulations.

  • 61.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, Kostas J.
    Connectivity preserving distributed swarm aggregation for multiple kinematic agents2007Inngår i: PROCEEDINGS OF THE 46TH IEEE CONFERENCE ON DECISION AND CONTROL, 2007, s. 3627-3632Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A distributed swarm aggregation algorithm is developed for a team of multiple kinematic agents. Each agent is assigned with a control law which is the sum of two elements: a repulsive potential field, which is responsible for the collision avoidance objective, and an attractive potential field, that drives the agents to a configuration where they are close to each other and forces the agents that are initially located within the sensing radius of an agent to remain within this area for all time. In this way, the connectivity properties of the initially formed communication graph are rendered invariant for the trajectories of the closed loop system. It is shown that agents converge to a configuration where each agent is located at a bounded distance from each of its neighbors. The results are also extended to the case of nonholonomic kinematic agents and to the dynamic edge addition case, for which we derive a better bound in the swarm size than in the static case.

  • 62.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, Kostas J.
    Further results on formation infeasibility and velocity alignment2007Inngår i: PROCEEDINGS OF THE 46TH IEEE CONFERENCE ON DECISION AND CONTROL, 2007, s. 4115-4120Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In previous work, we deduced that formation infeasibility results in velocity alignment in multi-agent systems with bidirectional communication topology and single integrator as well as nonholonomic kinematics. This paper contains additional results regarding the connection between formation infeasibility and velocity alignment. In particular, we obtain an analytic expression for the resulting common velocity vector in the case of formation infeasibility and extend the results to the case of unidirectional communication topology. The results are then extended to the case of a leader-follower architecture in which the followers are not aware of a global objective while the leaders are responsible for driving the team to the interior of a desired leader formation. When this formation is infeasible, we show that both leaders and followers attain a common velocity vector, of which an analytic expression is also provided. Computer simulations support the derived results.

  • 63.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, Kostas J.
    Inverse agreement algorithms with application to swarm dispersion for multiple nonholonomic agents2008Inngår i: 2008 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, 2008, s. 1973-1978Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We propose an inverse agreement control strategy for multiple nonholonomic agents that forces the team members to disperse in the workspace in a distributed manner. Both the cases of an unbounded and a circular bounded workspace are considered. In the first case, we show that the closed loop system reaches a configuration in which the minimum distance between any pair of agents is larger than a specific lower bound. It is proved that this lower bound coincides with the agents' sensing radius. In the case of a bounded workspace, the control law is modified to force the agents to remain within the workspace boundary throughout the closed loop system evolution. Moreover the proposed control guarantees collision avoidance between the team members. The results are supported through relevant computer simulations.

  • 64.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Tsiotras, P.
    Kyriakopoulos, K. J.
    Leader-follower cooperative attitude control of multiple rigid bodies2009Inngår i: Systems & control letters (Print), ISSN 0167-6911, E-ISSN 1872-7956, Vol. 58, nr 6, s. 429-435Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper we extend our previous results on coordinated control of rotating rigid bodies to the case of teams with heterogeneous agents. We assume that only a certain subgroup of the agents (the leaders) is vested with the main control objective, that is, maintain constant relative orientation amongst themselves. The other members of the team must meet relaxed control specifications, namely, maintain their respective orientations within certain bounds, dictated by the orientation of the leaders. The proposed control laws respect the limited information each rigid body has with respect to the rest of its peers (leaders or followers), as well as with the rest of the team. Each rigid body is equipped with a feedback control law that utilizes the Laplacian matrix of the associated communication graph, and which encodes the limited communication capabilities between the team members. Similarly to the single integrator case, the convergence of the system relies on the connectivity of the communication graph.

  • 65.
    Dimarogonas, Dimos V.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Tsiotras, Panagiotis
    Kyriakopoulos, Kostas J.
    Leader-follower cooperative attitude control of multiple rigid bodies2008Inngår i: 2008 AMERICAN CONTROL CONFERENCE, 2008, s. 801-806Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we extend our previous results on coordinated control of rotating rigid bodies to the case of teams with heterogenous agents. We assume that only a certain subgroup of the agents (the leaders) are vested with the main control objective, that is, maintain constant relative orientation amongst themselves. The rest of the team must meet relaxed control specifications, namely maintain their respective orientations within certain limits dictated by the orientation of the leaders. The proposed control laws respect the limited information each rigid body has with respect to the rest of its peers (leaders or followers) as well as with the rest of the team. Each rigid body is equipped with a control law that utilizes the Laplacian matrix of the associated communication graph, which encodes the communication links between the team members. Similarly to the linear case, the convergence of the multi-agent system relies on the connectivity of the communication graph.

  • 66. Durr, H. -B
    et al.
    Stankovic, M. S.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Ebenbauer, C.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Obstacle avoidance for an extremum seeking system using a navigation function2013Inngår i: Proceedings of the American Control Conference 2013, AACC American Automatic Control Council , 2013, s. 4062-4067Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 67. Eqtami, A.
    et al.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kyriakopoulos, K. J.
    Aperiodic model predictive control via perturbation analysis2012Inngår i: Decision and Control (CDC), 2012 IEEE 51st Annual Conference on, IEEE , 2012, s. 7193-7198Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 68. Eqtami, A.
    et al.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kyriakopoulos, K. J.
    Event-based model Predictive control for the cooperation of distributed agents2012Inngår i: 2012 American Control Conference (ACC), IEEE Computer Society, 2012, s. 6473-6478Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 69. Eqtami, A.
    et al.
    Heshmati-Alamdari, S.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kyriakopoulos, K. J.
    Self-triggered model predictive control for nonholonomic systems2013Inngår i: 2013 European Control Conference, ECC 2013, 2013, s. 638-643Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 70. Eqtami, A.
    et al.
    Heshmati-Alamdari, S.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kyriakopoulos, K. J.
    Self-triggered model predictive control framework for the cooperation of distributed nonholonomic agents2013Inngår i: 2013 IEEE 52nd Annual Conference on Decision and Control (CDC), IEEE conference proceedings, 2013, s. 7384-7389Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 71.
    Eqtami, Alina
    et al.
    NTUA.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, Kostas J.
    NTUA.
    Event-Triggered Strategies for Decentralized Model Predictive Controllers2011Inngår i: IFAC Proceedings Volumes (IFAC-PapersOnline), 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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

  • 72.
    Eqtami, Alina
    et al.
    NTUA.
    Dimarogonas, Dimos V.
    Kyriakopoulos, Kostas J.
    NTUA.
    Novel Event-Triggered Strategies for Model Predictive Controllers2011Inngår i: 2011 50TH IEEE CONFERENCE ON DECISION AND CONTROL AND EUROPEAN CONTROL CONFERENCE (CDC-ECC), 2011, s. 3392-3397Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 73. Filippidis, I.
    et al.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Kyriakopoulos, K. J.
    Decentralized multi-agent control from local LTL specifications2012Inngår i: Decision and Control (CDC), 2012 IEEE 51st Annual Conference on, IEEE , 2012, s. 6235-6240Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 74.
    Filotheou, Alexandros
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Nikou, Alexandros
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Decentralized Control of Uncertain Multi-Agent Systems with Connectivity Maintenance and Collision Avoidance2018Inngår i: 2018 European Control Conference, ECC 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 8-13, artikkel-id 8550343Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the problem of navigation control of a general class of uncertain nonlinear multi-agent systems in a bounded workspace, which is subset of \mathbb {R}^{n}, with static obstacles. In particular, we propose a decentralized control protocol such that each agent reaches a predefined position at the workspace, while using only local information based on a limited sensing radius. The proposed scheme guarantees that the initially connected agents remain always connected. In addition, by introducing certain distance constraints, we guarantee inter-agent collision avoidance, as well as, collision avoidance with the obstacles and the boundary of the workspace. The proposed controllers employ a class of Decentralized Nonlinear Model Predictive Controllers (DNMPC) under the presence of disturbances and uncertainties. Finally, simulation results verify the validity of the proposed framework.

  • 75.
    Giannis, Roussos
    et al.
    NTUA.
    Dimarogonas, Dimos V.
    Kyriakopoulos, Kostas J.
    NTUA.
    3D Navigation and Collision Avoidance for Nonholonomic aircraft-like vehicles2010Inngår i: International journal of adaptive control and signal processing (Print), ISSN 0890-6327, E-ISSN 1099-1115, Vol. 24, nr 10, s. 900-920Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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

  • 76.
    Giannis, Roussos
    et al.
    NTUA.
    Dimarogonas, Dimos V.
    Kyriakopoulos, Kostas J.
    NTUA.
    Distributed 3D Navigation and Collision Avoidance Nonholonomic Aircraft-like Vehicles2009Inngår i: Proceedings of 2009 European Control Conference, 2009Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Algorithms for robust failure or fault detection and identification (RFDI) in dynamic plants and control systems strive to be sensitive to the failures in plant components, while being insensitive to plant, failure and noise model uncertainties. In signal detection, sensitivity to signals of interest is also an objective, while robustness is concerned with undesirable interferences residing in unknown or partially known subspaces, and uncertainties in the signal and learned interference models. We will present the similarities and differences in the game theoretic formulations and solution approaches to robust detection in control systems and in signals. We will also show how ideas from RFDI in dynamic systems provide insight into robust detection in signals, and vice versa. We will discuss how the resulting innovative formulations and approaches to robust detection, estimation and learning are successfully addressing challenging problems in applications ranging from network flow to functional magnetic resonance imaging (fMRI) of the brain, to non-invasive image based classification of stem cells

  • 77. Guinaldo, M.
    et al.
    Dimarogonas, Dimos
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Lehmann, Daniel
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Distributed event-based control for interconnected linear systems2015Inngår i: Asynchronous Control for Networked Systems, Springer, 2015, s. 149-179Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    For large-scale interconnected systems, the control performance can be improved by means of distributed control solutions in which the subsystems communicate over the network. In this chapter, different distributed event-based control strategies are analyzed. Each subsystem broadcasts its state over the network according to certain triggering rules which depend on local information only.

  • 78. Guinaldo, M.
    et al.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Moreno, J. S.
    Dormido, S.
    Distributed event-based control for interconnected linear systems2011Inngår i: 2011 50th IEEE Conference on Decision and Control andEuropean Control Conference (CDC-ECC), 2011, s. 2553-2558Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 79. Guinaldo, Maria
    et al.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Johansson, Karl H.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Sanchez, Jose
    Dormido, Sebastian
    Distributed event-based control strategies for interconnected linear systems2013Inngår i: IET Control Theory & Applications, ISSN 1751-8644, E-ISSN 1751-8652, Vol. 7, nr 6, s. 877-886Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 80.
    Guo, Meng
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Andersson, Sofie
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES).
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Human-in-the-Loop Mixed-Initiative Control under Temporal Tasks2018Inngår i: 2018 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION (ICRA), IEEE Computer Society, 2018, s. 6395-6400Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper considers the motion control and task planning problem of mobile robots under complex high-level tasks and human initiatives. The assigned task is specified as Linear Temporal Logic (LTL) formulas that consist of hard and soft constraints. The human initiative influences the robot autonomy in two explicit ways: with additive terms in the continuous controller and with contingent task assignments. We propose an online coordination scheme that encapsulates (i) a mixed-initiative continuous controller that ensures all-time safety despite of possible human errors, (ii) a plan adaptation scheme that accommodates new features discovered in the workspace and short-term tasks assigned by the operator during run time, and (iii) an iterative inverse reinforcement learning (IRL) algorithm that allows the robot to asymptotically learn the human preference on the parameters during the plan synthesis. The results are demonstrated by both realistic human-in-the-loop simulations and experiments.

  • 81. Guo, Meng
    et al.
    Bechlioulis, Charalampos P.
    Kyriakopoulos, Kostas J.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma systen, CAS.
    Hybrid Control of Multiagent Systems With Contingent Temporal Tasks and Prescribed Formation Constraints2017Inngår i: IEEE Transactions on Big Data, ISSN 2325-5870, E-ISSN 2168-6750, Vol. 4, nr 4, s. 781-792Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we present a distributed hybrid control strategy for multiagent systems with contingent temporal tasks and prescribed formation constraints. Each agent is assigned a local task given as a linear temporal logic formula. In addition, two commonly seen kinds of cooperative robotic tasks, namely, service and formation, are requested and exchanged among the agents in real time. The service request is a short-term task provided by one agent to another. On the other hand, the formation request is a relative deployment requirement with predefined transient response imposed by an associated performance function. The proposed hybrid control strategy consists of four major components: 1) the contingent requests handlingmodule; 2) the real-time events monitoring module; 3) the local discrete plan synthesis module; and 4) the continuous control switching module, and it is shown that all local tasks and contingent service/formation requests are fulfilled. Finally, a simulated paradigm demonstrates the proposed control strategy.

  • 82.
    Guo, Meng
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma systen, CAS.
    Boskos, Dimitris
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma systen, CAS.
    Tumova, Jana
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Robotik, perception och lärande, RPL.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma systen, CAS.
    Distributed hybrid control synthesis for multi-agent systems from high-level specifications2018Inngår i: Control Subject to Computational and Communication Constraints, Springer Verlag , 2018, 475, s. 241-260Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Current control applications necessitate in many cases the consideration of systems with multiple interconnected components. These components/agents may need to fulfill high-level tasks at a discrete planning layer and also coupled constraints at the continuous control layer. Toward this end, the need for combined decentralized control at the continuous layer and planning at the discrete layer becomes apparent. While there are approaches that handle the problem in a top-down centralized manner, decentralized bottom-up approaches have not been pursued to the same extent. We present here some of our results for the problem of combined, hybrid control and task planning from high-level specifications for multi-agent systems in a bottom-up manner. In the first part, we present some initial results on extending the necessary notion of abstractions to multi-agent systems in a distributed fashion. We then consider a setup where agents are assigned individual tasks in the form of linear temporal logic (LTL) formulas and derive local task planning strategies for each agent. In the last part, the problem of combined distributed task planning and control under coupled continuous constraints is further considered.

  • 83.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Bottom-up motion and task coordination for loosely-coupled multi-agent systems with dependent local tasks2015Inngår i: IEEE International Conference on Automation Science and Engineering, IEEE , 2015, s. 348-355Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a bottom-up motion and task coordination scheme for loosely-coupled multi-agent systems under dependent local tasks. Instead of defining a global task for the whole team, each agent is assigned locally a task as syntactically co-safe linear temporal logic formulas that specify both motion and action requirements. Inter-agent dependency is introduced by collaborative actions of which the execution requires multiple agents' collaboration. The proposed solution contains an offline initial plan synthesis, an on-line request-reply messages exchange and a real-time plan adaptation algorithm. It is distributed in that any decision is made locally based on local computation and local communication within neighboring agents. It is scalable and resilient to agent failures as the dependency is formed and removed dynamically based on the plan execution status and agent capabilities, instead of pre-assigned agent identities. The overall scheme is demonstrated by a simulated scenario.

  • 84.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Consensus with quantized relative state measurements2013Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 49, nr 8, s. 2531-2537Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 85.
    Guo, Meng
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Distributed plan reconfiguration via knowledge transfer in multi-agent systems under local LTL specifications2014Inngår i: Proceedings - IEEE International Conference on Robotics and Automation, IEEE conference proceedings, 2014, s. 4304-4309Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 86.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Multi-agent plan reconfiguration under local LTL specifications2015Inngår i: The international journal of robotics research, ISSN 0278-3649, E-ISSN 1741-3176, Vol. 34, nr 2, s. 218-235Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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 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. This discrete plan is then implemented by the potential-field-based navigation controllers. While the system runs, each agent updates its knowledge about the workspace via its sensing capability and shares this knowledge with its neighbouring agents. Based on the knowledge update, each agent verifies and revises its motion plan in real time. It is ensured that the hard specification is always fulfilled for safety 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 and an experiment.

  • 87.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Nonlinear consensus via continuous, sampled, and aperiodic updates2013Inngår i: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, Vol. 86, nr 4, s. 567-578Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 88.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Quantized cooperative control using relative state measurements2011Inngår i: 2011 50th IEEE Conference on Decision and Control and European Control Conference, 2011, s. 5601-5606Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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

  • 89.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Reconfiguration in motion planning of single- And multi-agent systems under infeasible local LTL specifications2013Inngår i: 2013 IEEE 52nd Annual Conference on Decision and Control (CDC), IEEE conference proceedings, 2013, s. 2758-2763Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 90.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Task and Motion Coordination for Heterogeneous Multiagent Systems With Loosely Coupled Local Tasks2017Inngår i: IEEE Transactions on Automation Science and Engineering, ISSN 1545-5955, E-ISSN 1558-3783, Vol. 14, nr 2, s. 797-808Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider a multiagent system that consists of heterogeneous groups of homogeneous agents. Instead of defining a global task for the whole team, each agent is assigned a local task as syntactically cosafe linear temporal logic formulas that specify both motion and action requirements. Interagent dependence is introduced by collaborative actions, of which the execution requires multiple agents' collaboration. To ensure the satisfaction of all local tasks without central coordination, we propose a bottom-up motion and task coordination strategy that contains an off-line initial plan synthesis and an online coordination scheme based on real-time exchange of request and reply messages. It facilitates not only the collaboration among heterogeneous agents but also the task swapping between homogeneous agents to reduce the total execution cost. It is distributed as any decision is made locally by each agent based on local computation and communication within neighboring agents. It is scalable and resilient to agent failures as the dependence is formed and removed dynamically based on agent capabilities and their plan execution status, instead of preassigned agent identities. The overall scheme is demonstrated by a simulated scenario of 20 agents with loosely coupled local tasks.

  • 91.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Distributed real-time fault detection and isolation for cooperative multi-agent systems2012Inngår i: 2012 American Control Conference (ACC), IEEE Computer Society, 2012, s. 5270-5275Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 92.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Egerstedt, Magnus
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Hybrid control of multi-robot systems using embedded graph grammars2016Inngår i: Proceedings - IEEE International Conference on Robotics and Automation, IEEE conference proceedings, 2016, s. 5242-5247, artikkel-id 7487733Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose a distributed and cooperative motion and task control scheme for a team of mobile robots that are subject to dynamic constraints including inter-robot collision avoidance and connectivity maintenance of the communication network. Moreover, each agent has a local high-level task given as a Linear Temporal Logic (LTL) formula of desired motion and actions. Embedded graph grammars (EGGs) are used as the main tool to specify local interaction rules and switching control modes among the robots, which is then combined with the model-checking-based task planning module. It is ensured that all local tasks are satisfied while the dynamic constraints are obeyed at all time. The overall approach is demonstrated by simulation and experimental results.

  • 93.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl H.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Motion and Action Planning under LTL Specifications using Navigation Functions and Action Description Language2013Inngår i: 2013 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), IEEE , 2013, s. 240-245Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 94.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Revising motion planning under Linear Temporal Logic specifications in partially known workspaces2013Inngår i: 2013 IEEE International Conference on Robotics and Automation (ICRA), IEEE Computer Society, 2013, s. 5025-5032Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 95.
    Guo, Meng
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Tumova, Jana
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Communication-Free Multi-Agent Control Under Local Temporal Tasks and Relative-Distance Constraints2016Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 61, nr 12, s. 3948-3962Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose a distributed control and coordination strategy for multi-agent systems where each agent has a local task specified as a Linear Temporal Logic (LTL) formula and at the same time is subject to relative-distance constraints with its neighboring agents. The local tasks capture the temporal requirements on individual agents' behaviors, while the relative-distance constraints impose requirements on the collective motion of the whole team. The proposed solution relies only on relative-state measurements among the neighboring agents without the need for explicit information exchange. It is guaranteed that the local tasks given as syntactically co-safe or general LTL formulas are fulfilled and the relative-distance constraints are satisfied at all time. The approach is demonstrated with computer simulations.

  • 96.
    Guo, Meng
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Tumova, Jana
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Dimarogonas, Dimos V
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Cooperative decentralized multi-agent control under local LTL tasks and connectivity constraints2014Inngår i: Proceedings of the IEEE Conference on Decision and Control, IEEE conference proceedings, 2014, nr February, s. 75-80Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 97.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Tumova, Jana
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Dimarogonas, Dino V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Hybrid control of multi-agent systems under local temporal tasks and relative-distance constraints2016Inngår i: Proceedings of the IEEE Conference on Decision and Control, IEEE conference proceedings, 2016, s. 1701-1706Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we propose a distributed hybrid control strategy for multi-agent systems where each agent has a local task specified as a Linear Temporal Logic (LTL) formula and at the same time is subject to relative-distance constraints with its neighboring agents. The local tasks capture the temporal requirements on individual agents' behaviors, while the relative-distance constraints impose requirements on the collective motion of the whole team. The proposed solution relies only on relative-state measurements among the neighboring agents without the need for explicit information exchange. It is guaranteed that the local tasks given as syntactically co-safe or general LTL formulas are fulfilled and the relative-distance constraints are satisfied at all time. The approach is demonstrated with computer simulations.

  • 98.
    Guo, Meng
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Zavlanos, Michael M.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Controlling the Relative Agent Motion in Multi-Agent Formation Stabilization2014Inngår i: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 59, nr 3, s. 820-826Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 99.
    Gustavi, Tove
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Dimarogonas, Dimos V.
    Egerstedt, Magnus
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    On the Number of Leaders Needed to Ensure Network Connectivity in Arbitrary Dimensions2009Inngår i: MED: 2009 17TH MEDITERRANEAN CONFERENCE ON CONTROL & AUTOMATION, VOLS 1-3, NEW YORK: IEEE , 2009, s. 98-103Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We examine the leader-to-follower ratio needed to maintain connectivity in a leader-follower multi-agent network with proximity based communication topology. The paper extends the one-dimensional results of [2] to the two dimensional case. 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 objective of the leaders is to drag the team to the desired goal. In the paper we obtain bounds on the number of leaders needed to complete the task. The results are first established for an initially complete communication graph and then extended to the incomplete case. Computer simulations support the derived theory.

  • 100.
    Gustavi, Tove
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Dimarogonas, Dimos V.
    Laboratory for Information and Decision Systems, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
    Egerstedt, Magnus
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Sufficient conditions for connectivity maintenance and rendezvous in leader-follower networks2010Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 46, nr 1, s. 133-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

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