Practical issues in networked control systems

López, I.; Piovesan, Jorge; Abdallah, Chaouki T.; Lee, D.; Martinez, O.; Spong, Mark W.; Sandoval, Roberto Romero

doi:10.1109/acc.2006.1657378

Cited by 11 publications

(6 citation statements)

References 8 publications

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“…In case of the network of public communication in spite of the short distance of communication, sensor or control signal transfer and skipped information can be triggered in the networked control system ( Networked Control System, NCS) such as remote control or large formation control [4]. Also, in case of using network of dedicated communication, system of feedback control is very susceptible to information or timing of control signal.…”

Section: Multi-robotmentioning

confidence: 98%

Development of a dependable network using collective robots with restricted communication range

Kim

Park

Lee

et al. 2012

2012 9th International Conference on Ubiquitous Robots and Ambient Intelligence (URAI)

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In multi-robot systems, it is very important to maintain the network connectivity for cooperative behavior between robots. This paper describes a new method for deployment of wireless relay nodes. When applying rescue robots in building or underground city, connecting communication range is attenuated. In the paper, we divide multi-robot by leader robot, source robot, and relay robot. Using these robots, we propose communication control algorithm for connecting network communication.

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Section: Multi-robotmentioning

confidence: 98%

Development of a dependable network using collective robots with restricted communication range

Kim

Park

Lee

et al. 2012

2012 9th International Conference on Ubiquitous Robots and Ambient Intelligence (URAI)

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“…The reason for this choice is that UDP-like channels have been preferred by several experiments to avoid long, and potentially destabilizing delays, see [? ] and [5].…”

Section: Packet-losses Issuementioning

confidence: 98%

“…This second modulator is chosen with a ∆ 2 that creates a second region in which r 3 < |x(k)| < r 4 and where we enforce r 2 = r 3 . We denote this second region by R 2 as shown in figure (5). This selection will imply that ∆ 2 > ∆ 1 .…”

Section: A Increasing Sampling Timementioning

confidence: 99%

Gain-scheduling multi-bit Delta-Modulator for Networked Controlled System

López

Abdallah

Wit³

2007

2007 European Control Conference (ECC)

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We analyze in this paper stabilization issues for a Networked Control System that uses a Delta-Modulator Scheme within the encoder/decoder structures. We also analyze the packet-loss issue, and determine a maximum allowable number of consecutive bits lost while keeping stability. We then design a compensation scheme for re-synchronizing the encoder and decoder, after a bit is lost in a network without acknowledgment signals. We finally present a compensation scheme that ensures stability after a pre-determined number of bits is lost. Examples and simulations are provided to demonstrate the results.

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“…Stochastic transmission delays are usually observed in PSN (cf Salza, Draoli, Gaibisso, Palma, and Puccinelli (2000); Tanenbaum (2002); Lopez et al (2006)). These delays are the same for all data arriving in the same packet.…”

Section: Modeling Of Communication Channels Withmentioning

confidence: 98%

Consensus reaching in multi-agent packet-switched networks with non-linear coupling

Münz

Papachristodoulou

Allgöwer

2009

International Journal of Control

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An important task for multi-agent systems (MAS) is to reach a consensus, e.g. to align their velocity vectors. Recent results propose appropriate consensus protocols to achieve such tasks, but most of them do not consider the effect of communication constraints such as the presence of time-delays in the exchange of information between the agents. In this article, we provide conditions for a non-linear, locally passive MAS of arbitrary size to reach a consensus, when the agents communicate over a packet-switched network that is characterised by a given topology. Both the cases of constant and switching topologies are considered. The nature of the communication channel imposes constraints that are modelled using stochastic delays of arbitrary distribution. We first embed this model in another, distributed but deterministic delay model and provide conditions for the error introduced by this simplification. In our main result, we provide conditions for the locally passive MAS with distributed delays to reach a consensus. In the case of a fixed topology, the underlying directed graph has to contain a spanning tree. In the case of a switching topology, only the union graph of all graphs that persist over time is required to contain a spanning tree. These conditions are independent of the distribution and the size of the packet delays. To show attractivity of the consensus set, we use an invariance principle for systems described by functional differential equations based on an appropriate Lyapunov-Razumikhin function. This methodological approach is the main contribution of this work and can also be applied to other consensus problems with delays. We illustrate our results by numerical simulations showing synchronisation of non-linear Kuramoto oscillators over a digital network.

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Practical issues in networked control systems

Abstract: In this paper we expose experimental issues faced in a closed-loop networked control system. We also propose some compensation actions, and evaluate their performance for different experimental setups, focusing specifically on time delays.

Cited by 11 publications

References 8 publications

Development of a dependable network using collective robots with restricted communication range

Development of a dependable network using collective robots with restricted communication range

Gain-scheduling multi-bit Delta-Modulator for Networked Controlled System

Consensus reaching in multi-agent packet-switched networks with non-linear coupling

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