14,016 research outputs found
Decentralised delay-dependent static output feedback variable structure control
In this paper, an output feedback stabilisation problem is considered for a class of large scale interconnected time delay systems with uncertainties. The uncertainties appear in both isolated subsystems and interconnections. The bounds on the uncertainties are nonlinear and time delayed. It is not required that either the known interconnections or the uncertain interconnections are matched. Then, a decentralised delay-dependant static output feedback variable structure control is synthesised to stabilise the system globally uniformly asymptotically using the Lyapunov Razumikhin approach. A case study relating to a river pollution control problem is presented to illustrate the proposed approach
Delay-independent decentralised output feedback control for large-scale systems with nonlinear interconnections
In this paper, a stabilisation problem for a class of large-scale systems with nonlinear interconnections is considered. All the uncertainties are nonlinear and are subject to the effects of time delay. A decentralised static output feedback variable structure control is synthesised and the stability of the corresponding closed-loop system is analysed based on the Lyapunov Razumikhin approach. A set of conditions is developed to guarantee that the large-scale interconnected system is stabilised uniformly asymptotically. Further study shows that the conservatism can be reduced by employing additive controllers if the known interconnections are separated into matched and mismatched parts. It is not required that the subsystems are square. The designed controller is independent of time delay and thus it does not require memory. Simulation results show the effectiveness of the proposed approach
Decentralized pole assignment for interconnected systems
Given a general proper interconnected system,
this paper aims to design a LTI decentralized controller to
place the modes of the closed-loop system at pre-determined
locations. To this end, it is first assumed that the structural
graph of the system is strongly connected. Then, it is shown
applying generic static local controllers to any number of
subsystems will not introduce new decentralized fixed modes
(DFM) in the resultant system, although it has fewer inputoutput
stations compared to the original system. This means
that if there are some subsystems whose control costs are
highly dependent on the complexity of the control law, then
generic static controllers can be applied to such subsystems,
without changing the characteristics of the system in terms of
the fixed modes. As a direct application of this result, in the
case when the system has no DFMs, one can apply generic static
controllers to all but one subsystem, and the resultant system
will be controllable and observable through that subsystem.
Now, a simple observer-based local controller corresponding to
this subsystem can be designed to displace the modes of the
entire system arbitrarily. Similar results can also be attained
for a system whose structural graph is not strongly connected.
It is worth mentioning that similar concepts are deployed in the
literature for the special case of strictly proper systems, but as
noted in the relevant papers, extension of the results to general
proper systems is not trivial. This demonstrates the significance
of the present work
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