| 1. |
- Alexandre, Seuret, et al.
(författare)
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Consensus of Double Integrator Multi-agents under Communication Delay
- 2009
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Ingår i: IFAC Proceedings Volumes (IFAC-PapersOnline). - : Elsevier BV. - 1474-6670. ; , s. 376-381
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Konferensbidrag (refereegranskat)abstract
- This paper deals with the consensus problem under network induced communication delays. It is well-known that introducing a delay generally leads to a reduce of the performance or to instability. Thus, investigating the impact of time-delays in the consensus problem is an important issue. Another important issue is to obtain an estimate of the convergence rate, which is not straightforward when delays appear in the network. In this paper, the agents are modelled as double integrator systems. It is assumed that each agent receives instantaneously its own output information but receives the information from its neighbors after a constant delay. A stability criterion is provided based on Lyapunov-Krasovskii techniques and is expressed in terms of LMI. An expression of the consensus equilibrium which depends on the delay and on the initial conditions taken in an interval is derived. The results are supported through several simulations for different network symmetric communication schemes.
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| 2. |
- Barreau, Matthieu, et al.
(författare)
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Integral Quadratic Constraints on Linear Infinite-dimensional Systems for Robust Stability Analysis
- 2020
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Ingår i: Ifac papersonline. - : Elsevier BV. - 2405-8963. ; , s. 7752-7757
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a framework to assess the stability of an Ordinary Differential Equation (ODE) which is coupled to a 1D-partial differential equation (PDE). The stability theorem is based on a new result on Integral Quadratic Constraints (IQCs) and expressed in terms of two linear matrix inequalities with a moderate computational burden. The IQCs are not generated using dissipation inequalities involving the whole state of an infinite-dimensional system, but by using projection coefficients of the infinite-dimensional state. This permits to generalize our robustness result to many other PDEs. The proposed methodology is applied to a time-delay system and numerical results comparable to those in the literature are obtained.
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| 3. |
- Briat, Corentin, et al.
(författare)
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Convex Dwell-Time Characterizations for Uncertain Linear Impulsive Systems
- 2012
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Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 57:12, s. 3241-3246
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Tidskriftsartikel (refereegranskat)abstract
- New sufficient conditions for the characterization of dwell-times for linear impulsive systems are proposed and shown to coincide with continuous decrease conditions of a certain class of looped-functionals, a recently introduced type of functionals suitable for the analysis of hybrid systems. This approach allows to consider Lyapunov functions that evolve nonmonotonically along the flow of the system in a new way, broadening then the admissible class of systems which may be analyzed. As a byproduct, the particular structure of the obtained conditions makes the method is easily extendable to uncertain systems by exploiting some convexity properties. Several examples illustrate the approach.
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| 4. |
- De Campos, Gabriel Rodrigues, et al.
(författare)
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Distributed control of compact formations for multi-robot swarms
- 2018
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Ingår i: IMA Journal of Mathematical Control and Information. - : Oxford University Press. - 0265-0754 .- 1471-6887. ; 35:3, s. 805-835
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Tidskriftsartikel (refereegranskat)abstract
- This article proposes a distributed algorithm for the compact deployment of robots, using both distance-and angular-based arguments in the controllers' design. Our objective is to achieve a configuration maximizing the coverage of the environment while increasing the graph's connectivity. First, we provide: (i) a dispersion protocol guaranteeing connectivity maintenance; and (ii) a compactness controller with static and variable control gains that minimizes the inter-agent angles. Second, we present a sequential, multi-stage strategy and analyse its stability. Finally, we validate our theoretical results with simulations, where a group of robots are deployed to carry out sensing or communication tasks.
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| 5. |
- Jiang, W., et al.
(författare)
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Implementation of an internet-based remote controller with guaranteed exponential stabilization
- 2008
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Ingår i: Proceedings of the World Congress on Intelligent Control and Automation (WCICA). - 9781424421145 ; , s. 4063-4068
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Konferensbidrag (refereegranskat)abstract
- In this article, an Internet-based remote control system is designed and implemented. The communication is based on the Master-Slave structure. The Master PC communicates with the Slave from about 40km away by UDP protocol. In order to guarantee the Master and Slave clocks to be synchronized, the NTP (Network Time Protocol) is used in both sides. The packets are sent together with time-stamps. The controller design (master) relies on a remote observer that achieves a state prediction of the application (slave), despite the variable communication delays. The Slave comprises a PC and a robot Miabot of Merlin company. The protocol Bluetooth is used between the local PC and the robot. Internet-based remote systems are subject to variable time delays (including communication and data-sampling delays) and data packets losses (due to the unstable Internet network). We have continuously tested the RTT (round-trip-time) between the two PCs in the daytime and nighttime by the protocol ICMP (Internet Control Message). From these tests, an evaluation of the maximal time delay is obtained. Our structure allows one to guarantee an exponential stabilization performance, which is proven via a Lyapunov-Krassovski functional technique and involves the estimated delay upperbound. This means that the guaranteed decay rate is computed (via some LMI optimization) in relation to some maximal value of the communication delays. Of course, for greater delay values, the performance cannot be guaranteed anymore and an alternative solution has to be considered. In our system, we give a command for the robot to stop until the communication comes back to a sufficient quality.
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| 6. |
- Seuret, Alexandre, et al.
(författare)
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Commande de systèmes non retardés par retour de sortie statique échantillonné
- 2008
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Konferensbidrag (refereegranskat)abstract
- Il est connu que pour des systèmes linéaires il n’est pas toujours possible de construire une loi de commande par retour de sortie statique qui stabilise le système. Cet article propose une méthode qui permet d’élargir la classe de ces systèmes en ajoutant un retard et un échantillonnage dans la loi de commande qui sont optimisés pour un couple de gains de contrôleur donné par rapport aux performances des solutions et par rapport à la taille de la mémoire du contrôleur. Un exemple montre la pertinence de cette méthode.
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| 7. |
- Seuret, Alexandre, et al.
(författare)
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Consensus under communication delays
- 2008
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Ingår i: Proceedings of the IEEE Conference on Decision and Control. ; , s. 4922-4927
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 8. |
- Seuret, Alexandre, et al.
(författare)
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Networked control under time-synchronization errors
- 2009
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Ingår i: Networked control under time-synchronization errors. - 9783902661678 ; , s. 84-89
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Konferensbidrag (refereegranskat)abstract
- A robust controller is derived for networked control systems with uncertain plant dynamics. The link between the nodes is disturbed by time-varying communication delays, samplings and time-synchronization. A stability criterion for a robust control is presented in terms of LMIs based on Lyapunov-Krasovskii techniques. A second-order system example is considered and the relation between the admissive bounds of the synchronization error and the size of the uncertainties is computed.
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| 9. |
- Seuret, Alexandre, et al.
(författare)
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Networked control under time-synchronization errors
- 2012
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Ingår i: Time Delay Systems. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642252204 ; , s. 369-383
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Konferensbidrag (refereegranskat)abstract
- A robust controller is derived for networked control systems with uncertain plant dynamics. The link between the nodes is disturbed by time-varying communication delays, samplings and time-synchronization. A stability criterion for a robust control is presented in terms of LMIs based on Lyapunov-Krasovskii techniques. A second-order system example is considered and the relation between the admissive bounds of the synchronization error and the size of the uncertainties is computed.
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