7,208 research outputs found
Robust decentralized output regulation with single or multiple reference signals for uncertain heterogeneous systems
We consider the problem in which N coupled heterogeneous uncertain linear systems aim at tracking one or more reference signals generated by given exosystems under the restriction that not all the systems are directly connected to the exosystems. To tackle this problem, the reference signals are reconstructed via local interaction of the systems among themselves and the exosystems in accordance with the given communication graph. Then, decentralized robust controllers using the reconstructed reference signals are designed and shown to result in a closed-loop system whose outputs track the prescribed reference signals. Copyright (c) 2014 John Wiley & Sons, Ltd
Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View
Small satellite systems enable whole new class of missions for navigation,
communications, remote sensing and scientific research for both civilian and
military purposes. As individual spacecraft are limited by the size, mass and
power constraints, mass-produced small satellites in large constellations or
clusters could be useful in many science missions such as gravity mapping,
tracking of forest fires, finding water resources, etc. Constellation of
satellites provide improved spatial and temporal resolution of the target.
Small satellite constellations contribute innovative applications by replacing
a single asset with several very capable spacecraft which opens the door to new
applications. With increasing levels of autonomy, there will be a need for
remote communication networks to enable communication between spacecraft. These
space based networks will need to configure and maintain dynamic routes, manage
intermediate nodes, and reconfigure themselves to achieve mission objectives.
Hence, inter-satellite communication is a key aspect when satellites fly in
formation. In this paper, we present the various researches being conducted in
the small satellite community for implementing inter-satellite communications
based on the Open System Interconnection (OSI) model. This paper also reviews
the various design parameters applicable to the first three layers of the OSI
model, i.e., physical, data link and network layer. Based on the survey, we
also present a comprehensive list of design parameters useful for achieving
inter-satellite communications for multiple small satellite missions. Specific
topics include proposed solutions for some of the challenges faced by small
satellite systems, enabling operations using a network of small satellites, and
some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications
Surveys and Tutorial
Cluster synchronization of diffusively-coupled nonlinear systems: A contraction based approach
Finding the conditions that foster synchronization in networked oscillatory
systems is critical to understanding a wide range of biological and mechanical
systems. However, the conditions proved in the literature for synchronization
in nonlinear systems with linear coupling, such as has been used to model
neuronal networks, are in general not strict enough to accurately determine the
system behavior. We leverage contraction theory to derive new sufficient
conditions for cluster synchronization in terms of the network structure, for a
network where the intrinsic nonlinear dynamics of each node may differ. Our
result requires that network connections satisfy a cluster-input-equivalence
condition, and we explore the influence of this requirement on network
dynamics. For application to networks of nodes with neuronal spiking dynamics,
we show that our new sufficient condition is tighter than those found in
previous analyses which used nonsmooth Lyapunov functions. Improving the
analytical conditions for when cluster synchronization will occur based on
network configuration is a significant step toward facilitating understanding
and control of complex oscillatory systems
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