91 research outputs found
Distributed estimation techniques forcyber-physical systems
Nowadays, with the increasing use of wireless networks, embedded devices and agents with processing and sensing capabilities, the development of distributed estimation techniques has become vital to monitor important variables of the system that are not directly available. Numerous distributed estimation techniques have been proposed in the literature according to the model of the system, noises and disturbances.
One of the main objectives of this thesis is to search all those works that deal with distributed estimation techniques applied to cyber-physical systems, system of systems and heterogeneous systems, through using systematic review methodology. Even though systematic reviews are not the common way to survey a topic in the control community, they provide a rigorous, robust and objective formula that should not be ignored. The presented systematic review incorporates and adapts the
guidelines recommended in other disciplines to the field of automation and control and presents a brief description of the different phases that constitute a systematic review.
Undertaking the systematic review many gaps were discovered: it deserves to be remarked that some estimators are not applied to cyber-physical systems, such as sliding mode observers or set-membership observers. Subsequently, one of these particular techniques was chosen, set-membership estimator, to develop new applications for cyber-physical systems. This introduces the other objectives of the thesis, i.e. to present two novel formulations of distributed set-membership
estimators. Both estimators use a multi-hop decomposition, so the dynamics of the system is rewritten to present a cascaded implementation of the distributed set-membership observer, decoupling the influence of the non-observable modes to the observable ones. So each agent must find a different set for each sub-space, instead of a unique set for all the states. Two different approaches have been used to address the same problem, that is, to design a guaranteed distributed estimation method for linear full-coupled systems affected by bounded disturbances, to be implemented in a set of distributed agents that need to communicate and collaborate to achieve this goal
Finite-Time Resilient Formation Control with Bounded Inputs
In this paper we consider the problem of a multi-agent system achieving a
formation in the presence of misbehaving or adversarial agents. We introduce a
novel continuous time resilient controller to guarantee that normally behaving
agents can converge to a formation with respect to a set of leaders. The
controller employs a norm-based filtering mechanism, and unlike most prior
algorithms, also incorporates input bounds. In addition, the controller is
shown to guarantee convergence in finite time. A sufficient condition for the
controller to guarantee convergence is shown to be a graph theoretical
structure which we denote as Resilient Directed Acyclic Graph (RDAG). Further,
we employ our filtering mechanism on a discrete time system which is shown to
have exponential convergence. Our results are demonstrated through simulations
Towards a minimal order distributed observer for linear systems
In this paper we consider the distributed estimation problem for
continuous-time linear time-invariant (LTI) systems. A single linear plant is
observed by a network of local observers. Each local observer in the network
has access to only part of the output of the observed system, but can also
receive information on the state estimates of its neigbours. Each local
observer should in this way generate an estimate of the plant state. In this
paper we study the problem of existence of a reduced order distributed
observer. We show that if the observed system is observable and the network
graph is a strongly connected directed graph, then a distributed observer
exists with state space dimension equal to , where
is the number of network nodes, is the state space dimension of the
observed plant, and is the rank of the output matrix of the observed
output received by the th local observer. In the case of a single observer,
this result specializes to the well-known minimal order observer in classical
observer design.Comment: 12 pages, 1 figur
- …