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  • 151. Roussos, G. P.
    et al.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, K. J.
    3D navigation and collision avoidance for a non-holonomic vehicle2008Inngår i: Proceedings of the American Control Conference, 2008, s. 3512-3517Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper expands the methodology of Navigation Functions for the control of a spherical aircraft-like 3-dimensional nonholonomic vehicle. A Dipolar Navigation Function is used to generate a feasible, non-holonomic trajectory for the vehicle that leads from an arbitrary position to the target, in combination with a discontinuous feedback control law that steers the vehicle. The motion model used incorporates the nonholonomic constraints imposed on an aircraft, preventing any movement along the lateral or perpendicular axis, as well as preventing high yaw rotation rates. The control strategy provides guaranteed collision avoidance and convergence, and is supported by non-trivial simulation results.

  • 152. Rubio, F. R.
    et al.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Dimarogonas, Dimos
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Suboptimal distributed control and estimation: Application to a four coupled tanks system2015Inngår i: Asynchronous Control for Networked Systems, Springer Publishing Company, 2015, s. 193-221Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The chapter proposes an innovative estimation&control scheme that enables the distributed monitoring and control of large-scale processes. The proposed approach considers a discrete linear time-invariant process controlled by a network of agents that may both, collect information about the evolution of the plant and apply control actions to drive its behavior. The problem makes full sense when local observability/controllability is not assumed and the communication between agents can be exploited to reach system-wide goals. Additionally, to reduce agents bandwidth requirements and power consumption, an event-based communication policy is studied. The design procedure guarantees system stability, allowing the designer to trade-off performance, control effort, and communication requirements. The obtained controllers and observers are implemented in a fully distributed fashion. To illustrate the performance of the proposed technique, experimental results on a quadruple-tank process are provided.

  • 153.
    Schillinger, Philipp
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Bosch Center for Artificial Intelligence.
    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.
    Simultaneous Task Allocation and Planning for Temporal Logic Goals in Heterogeneous Multi-Robot SystemsInngår i: The international journal of robotics research, ISSN 0278-3649, E-ISSN 1741-3176Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes a framework for automatically generating optimal action-level behavior for a team of robots based on Temporal Logic mission specifications under resource constraints. The proposed approach optimally allocates separable tasks to available robots, without requiring a-priori an explicit representation of the tasks or the computation of all task execution costs. Instead, we propose an approach for identifying sub-tasks in an automaton representation of the mission specification and for simultaneously allocating the tasks and planning their execution. The proposed framework avoids the need of computing a combinatorial number of possible assignment costs, where each computation itself requires solving a complex planning problem. This can improve computational efficiency compared to classical assignment solutions, in particular for on-demand missions where task costs are unknown in advance. We demonstrate the applicability of the approach with multiple robots in an existing office environment and evaluate its performance in several case study scenarios.

  • 154.
    Schillinger, Philipp
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre. Bosch Ctr Artificial Intelligence, Renningen, Germany..
    Buerger, Mathias
    Bosch Ctr Artificial Intelligence, Renningen, Germany..
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Auctioning over Probabilistic Options for Temporal Logic-Based Multi-Robot Cooperation under Uncertainty2018Inngår i: 2018 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION (ICRA), IEEE Computer Society, 2018, s. 7330-7337Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Coordinating a team of robots to fulfill a common task is still a demanding problem. This is even more the case when considering uncertainty in the environment, as well as temporal dependencies within the task specification. A multirobot cooperation from a single goal specification requires mechanisms for decomposing the goal as well as an efficient planning for the team. However, planning action sequences offline is insufficient in real world applications. Rather, due to uncertainties, the robots also need to closely coordinate during execution and adjust their policies when additional observations are made. The framework presented in this paper enables the robot team to cooperatively fulfill tasks given as temporal logic specifications while explicitly considering uncertainty and incorporating observations during execution. We present the effectiveness of our ROS implementation of this approach in a case study scenario.

  • 155.
    Schillinger, Philipp
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Bosch Center for Artificial Intelligence.
    Buerger, Mathias
    Bosch Center for Artificial Intelligence.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Improving Multi-Robot Behavior Using Learning-Based Receding Horizon Task Allocation2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Planning efficient and coordinated policies for a team of robots is a computationally demanding problem, especially when the system faces uncertainty in the outcome or duration of actions. In practice, approximation methods are usually employed to plan reasonable team policies in an acceptable time. At the same time, many typical robotic tasks include a repetitive pattern. On the one hand, this multiplies the increased cost of inefficient solutions. But on the other hand, it also provides the potential for improving an initial, inefficient solution over time. In this paper, we consider the case that a single mission specification is given to a multi-robot system, describing repetitive tasks which allow the robots to parallelize work. We propose here a decentralized coordination scheme which enables the robots to decompose the full specification, execute distributed tasks, and improve their strategy over time.

  • 156.
    Schillinger, Philipp
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre. Bosch Ctr Artificial Intelligence, Robert Bosch Campus 1, DE-71272 Renningen, Germany.
    Buerger, Mathias
    Bosch Ctr Artificial Intelligence, Robert Bosch Campus 1, DE-71272 Renningen, Germany..
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Simultaneous task allocation and planning for temporal logic goals in heterogeneous multi-robot systems2018Inngår i: The international journal of robotics research, ISSN 0278-3649, E-ISSN 1741-3176, Vol. 37, nr 7, s. 818-838Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes a framework for automatically generating optimal action-level behavior for a team of robots based on temporal logic mission specifications under resource constraints. The proposed approach optimally allocates separable tasks to available robots, without requiring a priori an explicit representation of the tasks or the computation of all task execution costs. Instead, we propose an approach for identifying sub-tasks in an automaton representation of the mission specification and for simultaneously allocating the tasks and planning their execution. The proposed framework avoids the need to compute a combinatorial number of possible assignment costs, where each computation itself requires solving a complex planning problem. This can improve computational efficiency compared with classical assignment solutions, in particular for on-demand missions where task costs are unknown in advance. We demonstrate the applicability of the approach with multiple robots in an existing office environment and evaluate its performance in several case study scenarios.

  • 157.
    Schillinger, Philipp
    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. Robert Bosch GmbH.
    Bürger, Mathias
    Robert Bosch GmbH.
    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.
    Decomposition of Finite LTL Specifications for Efficient Multi-Agent Planning2016Inngår i: / [ed] Roderich Gross, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Generating verifiably correct execution strategies from Linear Temporal Logic (LTL) mission specifications avoids the need for manually designed robot behaviors. However, when incorporating a team of robot agents, the additional model complexity becomes a critical issue. Given a single finite LTL mission and a team of robots, we propose an automata-based approach to automatically identify possible decompositions of the LTL specification into sets of independently executable task specifications. Our approach leads directly to the construction of a team model with significantly lower complexity than other representations constructed with conventional methods. Thus, it enables efficient search for an optimal decomposition and allocation of tasks to the robot agents.

  • 158.
    Schillinger, Philipp
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. Bosch Center for Artificial Intelligence.
    Bürger, Mathias
    Bosch Center for Artificial Intelligence.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Hierarchical LTL-Task MDPs for Multi-Agent Coordination through Auctioning and Learning2019Inngår i: The international journal of robotics research, ISSN 0278-3649, E-ISSN 1741-3176Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Given a temporal behavior specification and a team of agents available for execution in a stochastic environment, it is still an open problem how to efficiently decompose and allocate the specification to the agents while coordinating their actions accordingly and while considering long-term performance under uncertain external events. Our proposed framework works towards this goal by constructing a so-called hierachical LTL-Task MDP automatically by formally decomposing a given temporal logic goal specification into a set of smaller MDP planning problems. In order to efficiently find a multi-agent policy in this generated LTL-Task MDP, we combine methods from planning under uncertainty and auction-based task allocation with techniques from reinforcement learning. A particular challenge is to consider uncertainty in the environment, which might require significant additional effort to satisfy the given specification. This is addressed here by a formalism that allows the agents to consider preparation of such possible future reactions instead of updating the set of tasks only after observing an event.

  • 159.
    Schillinger, Philipp
    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. Bosch Center for Artificial Intelligence, Germany.
    Bürger, Mathias
    Bosch Center for Artificial Intelligence, Germany.
    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.
    Multi-Objective Search for Optimal Multi-Robot Planning with Finite LTL Specifications and Resource Constraints2017Inngår i: 2017 IEEE International Conference on Robotics and Automation (ICRA), Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 768-774, artikkel-id 7989094Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present an efficient approach to plan action sequences for a team of robots from a single finite LTL mission specification. The resulting execution strategy is proven to solve the given mission with minimal team costs, e.g., with shortest execution time. For planning, an established graphbased search method based on the multi-objective shortest path problem is adapted to multi-robot planning and extended to support resource constraints. We further improve planning efficiency significantly for missions which consist of independent parts by using previous results regarding LTL decomposition. The efficiency and practicality of the ROS implementation of our approach is demonstrated in example scenarios.

  • 160.
    Schillinger, Philipp
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. Bosch Center for Artificial Intelligence.
    Bürger, Mathias
    Bosch Center for Artificial Intelligence.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Simultaneous Task Allocation and Planning2017Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    When planning behaviors for a multi-robot system based on a Temporal Logic specification of the mission, not only actions need to be planned, but also allocation of parts of the mission needs to be considered. Classically, this is seen as two independent problems. However, utilizing the interplay of allocation and planning bears the potential of improving the efficiency to find an optimal solution.

  • 161. Selvaratnam, Daniel D.
    et al.
    Shames, Iman
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Manton, Jonathan H.
    Ristic, Branko
    Co-operative Estimation for Source Localisation using Binary Sensors2017Inngår i: 2017 IEEE 56TH ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper considers the problem of localising a signal source using a team of mobile agents that can only detect the presence or absence of the signal. A background false detection rate and missed detection probability are incorporated into the assumptions. An estimation algorithm is proposed that discretizes the search environment into cells, and uses Bayesian techniques to approximate the posterior probability of each cell containing the source. Analytical results are presented for a range of specific cases, and simulations are used to investigate more complex scenarios.

  • 162.
    Seuret, Alexandre
    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.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Consensus under communication delays2008Inngår i: Proceedings of the IEEE Conference on Decision and Control, 2008, s. 4922-4927Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper deals with the consensus problem under communication network inducing delays. It is well-known that introducing a delay leads in general to a reduction of the performance or to instability due to the fact that timedelay systems are infinite dimensional. For instance, the set of initial conditions of a time-delay system is not a vector but a function taken in an interval. Therefore, investigating the effect of time-delays in the consensus problem is an important issue. In the present paper, we assume that each agent receives instantaneously its own state information but receives the state information from its neighbors after a constant delay. Two stability criteria are provided based on the frequency approach and on Lyapunov-Krasovskii techniques given in terms of LMI. An analytic expression of the consensus equilibrium which depends on the delay and on the initial conditions taken in an interval is derived. The efficiency of the method is tested for different network communication schemes.

  • 163. Seyboth, G. S.
    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.
    Control of multi-agent systems via event-based communication2011Inngår i: Proceedings of the 18th IFAC World Congress, 2011, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, the average consensus problem for multi-agent systems is addressed. A novel event-based control strategy is proposed which renders both control signals and state measurements, which are broadcast over the network, piecewise constant. This enables implementation on digital platforms such as microprocessors. Different triggering conditions guaranteeing convergence to an adjustable region around the average consensus point or asymptotic convergence to this point, respectively, are discussed. Numerical simulations show the effectiveness of this approach, outperforming traditional time-scheduled control in terms of load on the communication medium. Both single- and double-integrator agents are covered.

  • 164. Seyboth, G. S.
    et al.
    Dimarogonas, Dimos V.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Event-based scheduling in cooperative networked controlArtikkel i tidsskrift (Fagfellevurdert)
  • 165. Seyboth, Georg S.
    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.
    Frasca, Paolo
    Allgoewer, Frank
    On robust synchronization of heterogeneous linear multi-agent systems with static couplings2015Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 53, s. 392-399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper addresses cooperative control problems in heterogeneous groups of linear dynamical agents that are coupled by diffusive links. We study networks with parameter uncertainties, resulting in heterogeneous agent dynamics, and we analyze the robustness of their output synchronization. The networks under consideration consist of non-identical double-integrators and harmonic oscillators. The geometric approach to linear control theory reveals structural requirements for non-trivial output synchronization in such networks. Furthermore, a clock synchronization problem and a circular motion coordination problem are discussed as applications corresponding to these two network types. The results are illustrated by numerical simulations.

  • 166. Seyboth, G.S.
    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.
    Allgöwer, F.
    Static diffusive couplings in heterogeneous linear networks2012Inngår i: Estimation and Control of Networked Systems, Volume 3, Part 1, 2012, s. 258-263Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recently, necessary and sufficient conditions for output synchronization of linear systems via diffusive couplings have been reported. In this paper, we study the case when such conditions are not satisfied and exact synchronization is impossible. In particular, we study two kinds of heterogeneous linear networks: (i) non-identical harmonic oscillators and (ii) double-integrators. We show that static diffusive couplings render heterogeneous networks of harmonic oscillators asymptotically stable. Networks of non-identical double-integrators, in contrast, are not asymptotically stable but synchronize with bounded synchronization error depending on the network topology and the heterogeneity in the agent dynamics. Numerical examples illustrate the results.

  • 167. Simonetto, A.
    et al.
    Keviczky, T.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Distributed solution for a Maximum Variance Unfolding Problem with sensor and robotic network applications2012Inngår i: Communication, Control, and Computing (Allerton), 2012 50th Annual Allerton Conference on, IEEE , 2012, s. 63-70Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We focus on a particular non-convex networked optimization problem, known as the Maximum Variance Unfolding problem and its dual, the Fastest Mixing Markov Process problem. These problems are of relevance for sensor networks and robotic applications. We propose to solve both these problems with the same distributed primal-dual subgradient iterations whose convergence is proven even in the case of approximation errors in the calculation of the subgradients. Furthermore, we illustrate the use of the algorithm for sensor network applications, such as localization problems, and for mobile robotic networks applications, such as dispersion problems.

  • 168.
    Smith, Christian
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Karayiannidis, Ioannis
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Nalpantidis, Lazaros
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Gratal, Javier
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Qi, Peng
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Dimarogonas, Dimos
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Dual arm manipulation-A survey2012Inngår i: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 60, nr 10, s. 1340-1353Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Recent advances in both anthropomorphic robots and bimanual industrial manipulators had led to an increased interest in the specific problems pertaining to dual arm manipulation. For the future, we foresee robots performing human-like tasks in both domestic and industrial settings. It is therefore natural to study specifics of dual arm manipulation in humans and methods for using the resulting knowledge in robot control. The related scientific problems range from low-level control to high level task planning and execution. This review aims to summarize the current state of the art from the heterogenous range of fields that study the different aspects of these problems specifically in dual arm manipulation.

  • 169. Swartling, J.O.
    et al.
    Shames, I.
    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.
    Collective Circumnavigation2014Inngår i: Unmanned Systems: Mission Critical, ISSN 0892-4023, Vol. 2, nr 3, s. 219-229, artikkel-id 2:3Artikkel i tidsskrift (Fagfellevurdert)
  • 170. Syboth, G. S.
    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.
    Event-based broadcasting for multi-agent average consensus2013Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 49, nr 1, s. 245-252Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel control strategy for multi-agent coordination with event-based broadcasting is presented. In particular, each agent decides itself when to transmit its current state to its neighbors and the local control laws are based on these sampled state measurements. Three scenarios are analyzed: Networks of singleintegrator agents with and without communication delays, and networks of double-integrator agents. The novel event-based scheduling strategy bounds each agent’s measurement error by a time-dependent threshold. For each scenario it is shown that the proposed control strategy guarantees either asymptotic convergence to average consensus or convergence to a ball centered at the average consensus. Moreover, it is shown that the inter-event intervals are lower-bounded by a positive constant. Numerical simulations show the effectiveness of the novel event-based control strategy and how it compares to time-scheduled control.

  • 171. Teixeira, Pedro V.
    et al.
    Dimarogonas, Dimos V.
    Johansson, Karl H.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Sousa, João
    Multi-agent coordination with event-based communication2010Inngår i: Proceedings of the American Control Conference, IEEE , 2010, s. 824-829Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 172. Teixeira, Pedro V
    et al.
    Dimarogonas, Dimos V.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Borges De Sousa, João
    Event-based motion coordination of multiple underwater vehicles under disturbances2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    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.

  • 173.
    Theodosis, Dionysios
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS).
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Self-Triggered Control under Actuator Delays2018Inngår i: 2018 IEEE CONFERENCE ON DECISION AND CONTROL (CDC), IEEE , 2018, s. 1524-1529Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we address the problem of self-triggered control of nonlinear systems under actuator delays. In particular, for globally asymptotically stabilizable systems we exploit the Lipschitz properties of the system's dynamics, and present a self-triggered strategy that guarantees the stability of the sampled closed-loop system with bounded actuator delays.

  • 174. Tsiamis, Anastasios
    et al.
    Tumova, Jana
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Bechlioulis, Charalampos P.
    Karras, George C.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kyriakopoulos, Kostas J.
    Decentralized Leader-Follower Control under High Level Goals without Explicit Communication2015Inngår i: 2015 IEEE/RSJ INTERNATIONAL CONFERENCE ON INTELLIGENT ROBOTS AND SYSTEMS (IROS), IEEE , 2015, s. 5790-5795Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we study the decentralized control problem of a two-agent system under local goal specifications given as temporal logic formulas. The agents collaboratively carry an object in a leader-follower scheme and lack means to exchange messages on-line, i. e., to communicate explicitly. Specifically, we propose a decentralized control protocol and a leader re-election strategy that secure the accomplishment of both agents' local goal specifications. The challenge herein lies in exploiting exclusively implicit inter- robot communication that is a natural outcome of the physical interaction of the robots with the object. An illustrative experiment is included clarifying and verifying the approach.

  • 175.
    Tumova, Jana
    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.
    A Receding Horizon Approach to Multi-Agent Planning from Local LTL Specifications2014Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We study the problem of control synthesis for multi-agent systems, to achieve complex, high-level, long-term goals that are assigned to each agent individually. As the agents might not be capable of satisfying their respective goals by themselves, requests for other agents' collaborations are a part of the task descriptions. Particularly, we consider that the task specification takes a form of a linear temporal logic formula, which may contain requirements and constraints on the other agent's behavior. A traditional automata-based approach to multi-agent strategy synthesis from such specifications builds on centralized planning for the whole team and thus suffers from extreme computational demands. In this work, we aim at reducing the computational complexity by decomposing the strategy synthesis problem into short horizon planning problems that are solved iteratively, upon the run of the agents. We discuss the correctness of the solution and find assumptions, under which the proposed iterative algorithm leads to provable eventual satisfaction of the desired specifications.

  • 176.
    Tumova, Jana
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Multi-agent planning under local LTL specifications and event-based synchronization2016Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 70, s. 239-248Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study the problem of plan synthesis for multi-agent systems, to achieve complex, high-level, long-term goals that are assigned to each agent individually. As the agents might not be capable of satisfying their respective goals by themselves, requests for other agents' collaborations are a part of the task descriptions. We consider that each agent is modeled as a discrete state-transition system and its task specification takes a form of a linear temporal logic formula. A traditional automata-based approach to multi-agent plan synthesis from such specifications builds on centralized team planning and full team synchronization after each agents' discrete step, and thus suffers from extreme computational demands. We aim at reducing the computational complexity by decomposing the plan synthesis problem into finite horizon planning problems that are solved iteratively, upon the run of the agents. We introduce an event-based synchronization that allows our approach to efficiently adapt to different time durations of different agents' discrete steps. We discuss the correctness of the solution and find assumptions, under which the proposed iterative algorithm leads to provable eventual satisfaction of the desired specifications.

  • 177.
    Tumova, Jana
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dino V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Decomposition of multi-agent planning under distributed motion and task LTL specifications2016Inngår i: Proceedings of the IEEE Conference on Decision and Control, IEEE conference proceedings, 2016, s. 7448-7453Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this work is to introduce an efficient procedure for discrete multi-agent planning under local complex temporal logic behavior specifications. While the first part of an agent's behavior specification constraints the agent's trace and is independent, the second part of the specification expresses the agent's tasks in terms of the services to be provided along the trace and may impose requests for the other agents' collaborations. To fight the extreme computational complexity of centralized multi-agent planning, we propose a two-phase automata-based solution, where we systematically decouple the planning procedure for the two types of specifications. At first, we only consider the former specifications in a fully decentralized way and we compactly represent each agents' admissible traces by abstracting away the states that are insignificant for the satisfaction of their latter specifications. Second, the synchronized planning procedure uses only the compact representations. The satisfaction of the overall specification is guaranteed by construction for each agent.

  • 178.
    Tumova, Jana
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Marzinotto, Alejandro
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Maximally Satisfying LTL Action Planning2014Inngår i: 2014 IEEE/RSJ International Conference on Intelligent Robots and Systems, (IROS 2014), IEEE , 2014, s. 1503-1510Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We focus on autonomous robot action planning problem from Linear Temporal Logic (LTL) specifications, where the action refers to a "simple" motion or manipulation task, such as "go from A to B" or "grasp a ball". At the high-level planning layer, we propose an algorithm to synthesize a maximally satisfying discrete control strategy while taking into account that the robot's action executions may fail. Furthermore, we interface the high-level plan with the robot's low-level controller through a reactive middle-layer formalism called Behavior Trees (BTs). We demonstrate the proposed framework using a NAO robot capable of walking, ball grasping and ball dropping actions.

  • 179.
    van de Hoef, Sebastian
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Tsiotras, Panagiotes
    Spectral analysis of extended consensus algorithms for multiagent systems2014Inngår i: Decision and Control (CDC), 2014 IEEE 53rd Annual Conference on, 2014, s. 2204-2209Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We analyze an extension of the well-known linear consensus protocol for agents moving in two dimensions, where the standard consensus feedback is multiplied with a rotation matrix. This leads to a richer family of trajectories, and if only the new feedback term is applied, periodic solutions emerge. For special configurations of the controller gains, the form of the system trajectories is given in terms of the eigenvalues and eigenvectors of the closed-loop system matrix. We characterize the resulting closed-loop trajectories for specific choices of the controller gains and of the communication graph topology. Furthermore, the control strategy is extended to agents with double integrator dynamics. It is shown that stability is achieved with sufficiently large velocity feedback. The effect of this feedback on the overall system performance is further investigated. We finally provide simulations to illustrate the theoretical results.

  • 180.
    van de Hoef, Sebastian
    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.
    Computing Feasible Vehicle Platooning Opportunities for Transport Assignments2016Inngår i: IFAC PAPERSONLINE, 2016, Vol. 49, nr 3, s. 43-48Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Vehicle platooning facilitates the partial automation of vehicles and can significantly reduce fuel consumption. Mobile mummification infrastructure makes it possible to dynamically coordinate the formation of platoons en route. We consider a centralized system that provides trucks with routes and speed profiles allowing them to dynamically form platoons during their journeys. For this to work, all possible pairs of vehicles that can platoon based on their location, destination, and other constraints have to be identified. The presented approach scales well to large vehicle fleets and realistic road networks by extracting features from the transport assignments of the vehicles and rules out a majority of possible pairs based on these features only. Merely a small number of remaining pairs are considered in depth by a complete and computationally expensive algorithm. This algorithm conclusively decides if platooning is possible for a pair based on the complete data associated with the two vehicles. We derive appropriate features for the problem and demonstrate the effectiveness of the approach in a simulation example.

  • 181. van de Hoef, Sebastian
    et al.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Coordinating Truck Platooning by Clustering Pairwise Fuel-Optimal Plans2015Inngår i: IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, IEEE conference proceedings, 2015, s. 408-415Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider the fuel-optimal coordination of trucks into platoons. Truck platooning is a promising technology that enables trucks to save significant amounts of fuel by driving close together and thus reducing air drag. We study how fuel-optimal speed profiles for platooning can be computed. A first-order fuel model is considered and pairwise optimal plans are derived. We formulate an optimization problem that combines these pairwise plans into an overall plan for a large number of trucks. The problem resembles a medoids clustering problem. We propose an approximation algorithm similar to the partitioning around medoids algorithm and discuss its convergence. The method is evaluated with Monte Carlo simulations. We demonstrate that the proposed algorithm can compute a plan for thousands of trucks and that significant fuel savings can be achieved.

  • 182.
    van de Hoef, Sebastian
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), 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.
    Efficient Dynamic Programming Solution to a Platoon Coordination Merge Problem With Stochastic Travel Times2017Inngår i: IFAC-PapersOnLine, ISSN 2405-8963, Vol. 50, nr 1, s. 4228-4233Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The problem of maximizing the probability of two trucks being coordinated to merge into a platoon on a highway is considered. Truck platooning is a promising technology that allows heavy vehicles to save fuel by driving with small automatically controlled inter-vehicle distances. In order to leverage the full potential of platooning, platoons can be formed dynamically en route by small adjustments to their speeds. However, in heavily used parts of the road network, travel times are subject to random disturbances originating from traffic, weather and other sources. We formulate this problem as a stochastic dynamic programming problem over a finite horizon, for which solutions can be computed using a backwards recursion. By exploiting the characteristics of the problem, we derive bounds on the set of states that have to be explored at every stage, which in turn reduces the complexity of computing the solution. Simulations suggest that the approach is applicable to realistic problem instances.

  • 183.
    van de Hoef, Sebastian
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    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), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Fuel-optimal centralized coordination of truck platooning based on shortest paths2015Inngår i: Proceedings of the American Control Conference, IEEE , 2015, s. 3740-3745Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Platooning is a way to significantly reduce fuel consumption of trucks. Vehicles that drive at close inter-vehicle distance assisted by automatic controllers experience substantially lower air-drag. In this paper, we deal with the problem of coordinating the formation and the breakup of platoons in a fuel-optimal way. We formulate an optimization problem which accounts for routing, speed-dependent fuel consumption, and platooning decisions. An algorithm to obtain an approximate solution to the problem is presented. It first determines the shortest path for each truck. Then, possible platoon configurations are identified. For a certain platoon configuration the optimal speed profile is the solution to a convex program. The algorithm is illustrated by a realistic example.

  • 184.
    Verginis, Christos
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Bechlioulis, Charalampos
    Dimarogonas, Dimos V
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Kyriakopoulos, Kostas
    Decentralized 2-D Control of Vehicular Platoons under Limited Visual Feedback2015Inngår i: IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Hamburg, Germany, Sept. 28 2015-Oct. 2 2015, IEEE conference proceedings, 2015, s. 3566-3571Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we consider the two dimensional (2-D) predecessor-following control problem for a platoon of unicycle vehicles moving on a planar surface. More specifically, we design a decentralized kinematic control protocol, in the sense that each vehicle calculates its own control signal based solely on local information regarding its preceding vehicle, by its on-board camera, without incorporating any velocity measurements. Additionally, the transient and steady state response is a priori determined by certain designer-specified performance functions and is fully decoupled by the number of vehicles composing the platoon and the control gains selection. Moreover, collisions between successive vehicles as well as connectivity breaks, owing to the limited field of view of cameras, are provably avoided. Finally, an extensive simulation study is carried out in the WEBOTS realistic simulator, clarifying the proposed control scheme and verifying its effectiveness.

  • 185.
    Verginis, Christos K.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Dimarogonas, Dimos V.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Robust Decentralized Abstractions for Multiple Mobile Manipulators2017Inngår i: 2017 IEEE 56th Annual Conference on Decision and Control, CDC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the problem of decentralized abstractions for multiple mobile manipulators with 2nd order dynamics. In particular, we propose decentralized controllers for the navigation of each agent among predefined regions of interest in the workspace, while guaranteeing at the same time inter-agent collision avoidance and connectivity maintenance for a subset of initially connected agents. In that way, the motion of the coupled multi-agent system is abstracted into multiple finite transition systems for each agent, which are then suitable for the application of temporal logic-based high level plans. The proposed methodology is decentralized, since each agent uses local information based on limited sensing capabilities. Finally, simulation studies verify the validity of the approach.

  • 186.
    Verginis, Christos K.
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Timed abstractions for distributed cooperative manipulation2018Inngår i: Autonomous Robots, ISSN 0929-5593, E-ISSN 1573-7527, Vol. 42, nr 4, s. 781-799Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper addresses the problem of deriving well-defined timed abstractions for the decentralized cooperative manipulation of a single object by N robotic agents. In particular, we propose a distributed model-free control protocol for the trajectory tracking of the cooperatively manipulated object without necessitating feedback of the contact forces/torques or inter-agent communication. Certain prespecified performance functions determine the transient and steady state of the coupled object-agents system. The latter, along with a region partition of the workspace that depends on the physical volume of the object and the agents, allows us to define timed transitions for the coupled system among the derived workspace regions. Therefore, we abstract its motion as a finite transition system and, by employing standard automata-based methodologies, we define high level complex tasks for the object that can be encoded by timed temporal logics. In addition, we use load sharing coefficients to represent potential differences in power capabilities among the agents. Finally, realistic simulation studies verify the validity of the proposed scheme.

  • 187.
    Verginis, Christos K.
    et al.
    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.
    Nikou, Alexandros
    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.
    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.
    Communication-based Decentralized Cooperative Object Transportation Using Nonlinear Model Predictive Control2018Inngår i: 2018 European Control Conference, ECC 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 733-738, artikkel-id 8550305Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the problem of cooperative transportation of an object rigidly grasped by N robotic agents. We propose a decentralized Nonlinear Model Predictive Control (NMPC) scheme that guarantees the navigation of the object to a desired pose in a bounded workspace with obstacles, while complying with certain input saturations of the agents. The control scheme is based on inter-agent communication and is decentralized in the sense that each agent calculates its own control signal. Moreover, the proposed methodology ensures that the agents do not collide with each other or with workspace obstacles as well as that they do not pass through singular configurations. Finally, simulation results illustrate the validity and efficiency of the proposed method.

  • 188.
    Verginis, Christos K.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Nikou, Alexandros
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Position and Orientation Based Formation Control of Multiple Rigid Bodies with Collision Avoidance and Connectivity Maintenance2017Inngår i: 2017 IEEE 56th Annual Conference on Decision and Control, CDC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, s. 411-416Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper addresses the problem of position-and orientation-based formation control of a class of second-order nonlinear multi-agent systems in a 3D workspace with obstacles. More specifically, we design a decentralized control protocol such that each agent achieves a predefined geometric formation with its initial neighbors, while using local information based on a limited sensing radius. The latter implies that 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. Finally, simulation results verify the validity of the proposed framework.

  • 189.
    Verginis, Christos
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Mastellaro, Matteo
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Robust Cooperative Manipulation Without Force/Torque Measurements: Control Design and Experiments2019Inngår i: IEEE Transactions on Control Systems Technology, ISSN 1063-6536, E-ISSN 1558-0865Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents two novel control methodologies for the cooperative manipulation of an object by  N robotic agents. First, we design an adaptive control protocol which employs quaternion feedback for the object orientation to avoid potential representation singularities. Second, we propose a control protocol that guarantees predefined transient and steady-state performance for the object trajectory. Both methodologies are decentralized, since the agents calculate their own signals without communicating with each other, as well as robust to external disturbances and model uncertainties. Moreover, we consider that the grasping points are rigid and avoid the need for force/torque measurements. Load distribution is also included via a grasp matrix pseudoinverse to account for potential differences in the agents’ power capabilities. Finally, simulation and experimental results with two robotic arms verify the theoretical findings.

  • 190.
    Verginis, Christos
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Nikou, Alexandros
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, Centrum för autonoma system, CAS. KTH, Skolan för elektroteknik och datavetenskap (EECS), Centra, ACCESS Linnaeus Centre.
    Robust formation control in SE(3) for tree-graph structures with prescribed transient and steady state performance2019Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 103, s. 538-548Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents a novel control protocol for distance and orientation formation control of rigid bodies, whose sensing graph is a static and undirected tree, in the special Euclidean group SE(3). The proposed control laws are decentralized, in the sense that each agent uses only local relative information from its neighbors to calculate its control signal, as well as robust with respect to modeling (parametric and structural) uncertainties and external disturbances. The proposed methodology guarantees the satisfaction of inter-agent distance constraints that resemble collision avoidance and connectivity maintenance properties. Moreover, certain predefined functions characterize the transient and steady state performance of the closed loop system. Finally, simulation results verify the validity and efficiency of the proposed approach.

  • 191.
    Verginis, Christos
    et al.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Vrohidis, Constantinos
    Bechlioulis, Charalampos
    Kyriakopoulos, Kostas
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Reconfigurable Motion Planning and Control in Obstacle Cluttered Environments under Timed Temporal Tasks2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This work addresses the problem of robot navigation under timed temporal specifications in workspaces cluttered with obstacles. We propose a hybrid control strategy that guarantees the accomplishment of a high-level specification expressed as a timed temporal logic formula, while preserving safety (i.e., obstacle avoidance) of the system. In particular, we utilize a motion controller that achieves safe navigation inside the workspace in predetermined time, thus allowingus to abstract the motion of the agent as a finite timed transition system among certain regions of interest. Next, we employ standard formal verification and convex optimization techniques to derive high-level timed plans that satisfy the agent’s specifications. A simulation study illustrates and clarifies the proposed scheme.

  • 192.
    Vizins, Kim
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dimarogonas, Dimons
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Wahlberg, Bo
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Modeling and control of dual arm robotic manipulators using decentralized navigation functions2012Inngår i: IFAC Proc. Vol. (IFAC-PapersOnline), 2012, s. 241-246Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We apply multi-agent systems' techniques to the control of dual arm robotic manipulators. The paper is divided into two separate subproblems: the first one considers decentralized navigation of a non-holonomic two-agent system with collision avoidance, corresponding to the end effectors of the robotic arms. For this problem, a controller that guarantees convergence to an arbitrarily small region around the desired destination is proposed. The second subproblem considers decentralized connectivity preserving control of a holonomic multi-agent system of fingers associated with the end effectors. Here, the goal is to account for the angle constraints that are necessary to describe the relationship between fingers connected to the same hand. For this case, both connectivity and convergence are shown with the proposed controller.

  • 193.
    Wei, Jieqiang
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Verginis, Christos
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Wu, J.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Sandberg, Henrik
    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.
    Asymptotic and finite-time almost global attitude tracking: Representations free approach2018Inngår i: 2018 European Control Conference, ECC 2018, Institute of Electrical and Electronics Engineers (IEEE), 2018, s. 3126-3131, artikkel-id 8550190Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, the attitude tracking problem is considered using the rotation matrices. Due to the inherent topological restriction, it is impossible to achieve global attractivity with any continuous attitude control system on SO(3). Hence in this work, we propose some control protocols achieving almost global tracking asymptotically and in finite time, respectively. In these protocols, no world frame is needed and only relative state information are requested. For finitetime tracking case, Filippov solutions and non-smooth analysis techniques are adopted to handle the discontinuities. Simulation examples are provided to verify the performances of the control protocols designed in this paper.

  • 194. Wiget, R.
    et al.
    Andersson, G.
    Andreasson, Martin
    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.
    Johansson, Karl H.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Dynamic simulation of a combined AC and MTDC grid with decentralized controllers to share primary frequency control reserves2015Inngår i: 2015 IEEE Eindhoven PowerTech, PowerTech 2015, IEEE conference proceedings, 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The use of multi-terminal HVDC grids is a promising option to tackle the coming challenges in long distance power transmission, but the combined operation of HVDC and AC grids will bring certain challenges. The dynamic interaction from the fast controllable converter station with the rotational inertia dependent AC grids has to be investigated in detail, as well as how the converter stations will be controlled in the static and dynamic case. This paper will focus on the dynamic case and proposes a decentralized controller structure to control the HVDC converter power set-points. The proposed controller does not rely on real-time communication nor on a slack bus. A simulation study is presented to demonstrate the implementation of the controller.

  • 195.
    Yang, Tao
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Meng, Ziyang
    Dimarogonas, Dimos V.
    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.
    Periodic Behaviors for Discrete-Time Second-Order Multiagent Systems With Input Saturation Constraints2016Inngår i: IEEE Transactions on Circuits and Systems - II - Express Briefs, ISSN 1549-7747, E-ISSN 1558-3791, Vol. 63, nr 7, s. 663-667Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This brief considers the existence of periodic behaviors for discrete-time second-order multiagent systems with input saturation constraints. We first consider the case where the agent dynamics is a double integrator and then establish conditions on the feedback gains of the linear consensus control law for achieving periodic behaviors. This, in turn, shows that the previously established sufficient condition for reaching global consensus has a necessary aspect since these two conditions are exclusive. We further consider all other second-order agent dynamics and show that these multiagent systems under the linear consensus law exhibit periodic solutions provided the feedback gains satisfy certain conditions. Simulation results are used to validate the theoretical findings.

  • 196.
    Yang, Tao
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Meng, Ziyang
    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.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Global consensus for discrete-time multi-agent systems with input saturation constraints2014Inngår i: Automatica, ISSN 0005-1098, E-ISSN 1873-2836, Vol. 50, nr 2, s. 499-506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we consider the global consensus problem for discrete-time multi-agent systems with input saturation constraints under fixed undirected topologies. We first give necessary conditions for achieving global consensus via a distributed protocol based on relative state measurements of the agent itself and its neighboring agents. We then focus on two special cases, where the agent model is either neutrally stable or a double integrator. For the neutrally stable case, any linear protocol of a particular form, which solves the consensus problem for the case without input saturation constraints, also solves the global consensus problem for the case with input saturation constraints. For the double integrator case, we show that a subset of linear protocols, which solve the consensus problem for the case without saturation constraints, also solve the global consensus problem for the case with input saturation constraints. The results are illustrated by numerical simulations.

  • 197.
    Yang, Tao
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Meng, Ziyang
    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.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Global consensus in homogeneous networks of discrete-time agents subject to actuator saturation2013Inngår i: 2013 European Control Conference, ECC 2013, IEEE , 2013, s. 244-249Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we give necessary conditions for achieving global consensus in homogeneous networks of discrete-time linear time-invariant agents with input saturation constraints under fixed undirected topologies. For two special cases, where the agent model is either neutrally stable or a double integrator, these necessary conditions together with a gain condition are also sufficient. We show this by designing a linear protocol based on the combination of state differences between the agent and its neighbors. In particular, for the neutrally stable case, we show that any linear protocol of a particular form which solves the consensus problem for the case without input saturation constraints also solves the global consensus problem for the case with input saturation constraints. For the double integrator case, we show that a subset of linear protocols which solve the consensus problem for the case without saturation constraints also solve the global consensus problem in the presence of input saturation. The results are illustrated by numerical simulations.

  • 198.
    Yang, Tao
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Meng, Ziyang
    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.
    Johansson, Karl Henrik
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    Periodic behaviors in multi-agent systems with input saturation constraints2013Inngår i: 2013 IEEE 52nd Annual Conference on Decision and Control (CDC), IEEE conference proceedings, 2013, s. 4467-4472Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, we give conditions for the existence of periodic behaviors in a multi-agent system of identical discrete-time double integrators with input saturation constraints. If the feedback gain parameters of the controllers, which are based on relative state measurements of the agent itself and its neighboring agents, are bounded by a value depending on the largest eigenvalue of the Laplacian matrix, then the multi-agent system exhibits a periodic solution for certain initial conditions.

  • 199. Yang, Y.
    et al.
    Dimarogonas, Dimos V.
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Reglerteknik.
    Hu, X.
    Opinion consensus under external influences2018Inngår i: Systems & control letters (Print), ISSN 0167-6911, E-ISSN 1872-7956, Vol. 119, s. 23-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As a means to regulate the continuous-time bounded confidence opinion dynamics, an exo-system to the original Hegselmann–Krause model is added. Some analysis is made about the properties of the combined system. Two theorems are provided in this article in terms of sufficient conditions of the exo-system that can guarantee opinion consensus for any initial conditions. Two more corollaries are given to describe the resulting synchronized opinions. 

  • 200.
    Yang, Yuecheng
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Dimarogonas, Dimos
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik.
    Hu, Xiaoming
    KTH, Skolan för teknikvetenskap (SCI), Matematik (Inst.), Optimeringslära och systemteori.
    Shaping up crowd of agents through controlling their statistical moments2015Inngår i: 2015 European Control Conference, ECC 2015, Institute of Electrical and Electronics Engineers (IEEE), 2015, s. 1017-1022Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In a crowd model based on leader-follower interactions, where positions of the leaders are viewed as the control input, up-to-date solutions rely on knowledge of the agents' coordinates. In practice, it is more realistic to exploit knowledge of statistical properties of the group of agents, rather than their exact positions. In order to shape the crowd, we study thus the problem of controlling the moments instead, since it is well known that shape can be determined by moments. An optimal control for the moments tracking problem is obtained by solving a modified Hamilton-Jacobi-Bellman (HJB) equation, which only uses the moments and leaders' states as feedback. The optimal solution can be solved fast enough for on-line implementations.

12345 151 - 200 of 223
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