It is widely understood that communication is a critical technological factor in designing autonomous unmanned
networks consisting of a large number of heterogeneous nodes that may be configured in ad-hoc fashions and
incorporating intricate architectures. In fact, one of the challenges in this field is to recognize the entire network as
a heterogenous collection of physical and information systems with complicated interconnections and interactions.
Using high data rates that are essential for real-time interactive command and control systems, these networks
require utilization of optimal integration of local feedback loops into a scheduling and resource allocation systems.
This integration becomes particularly problematic in presence of latencies and delays.
Given that dynamics of a network of unmanned systems could easily become unstable depending on interconnections
among nodes, in this paper stability of the resulting time-delayed controlled network based on
configuration changes is studied. We also formally investigate sufficient conditions for our proposed robust resource
allocation strategies to be able to cope with these interconnections and time-delays in an optimal fashion.
Our time-delayed dependent network consists of three nodes that can be configured into different architectures.
To model our traffic and network we use a fluid flow model that is of low order and simpler than a detailed
Markovian queueing probabilistic model. Using sliding mode-based variable structure control (SM-VSC) techniques
that enjoy robustness capabilities, we design on the basis of an inaccurate/uncertain model our proposed
robust nonlinear feedback-based control approaches. The results presented are analyzed analytically to guarantee
stability of known/unknown time-delayed dependent network of unmanned systems for different configurations.
Large scale unmanned networks consisting of a number of heterogeneous
nodes that may be configured in ad-hoc fashions and incorporating complicated
architectures result in challenging problems
for design of appropriate control and resource allocation
optimization techniques. The problem is further compounded by
the fact that designing appropriate network control methodologies
subject to bandwidth, latencies and computational resources for these
network-centric systems are highly non-trivial.
In this paper, we only investigate one of a number
of critical issues that are of interest in this domain, namely
the problem of congestion control of a network
that consists of three nodes
that can be configured into different architectures.
This study shows that depending on the
interconnections between the network nodes the dynamics of
the resulting closed-loop system can change
considerably so that the unmanned system could become even unstable
Therefore, a robust control strategy is required to be able to cope with any
configuration changes and to be able to address
the resource allocation problem subject to the propagation delays and latencies.
For sake of comparative evaluation, we first implement a standard PID
control scheme which is shown to lack sufficient capability
for achieving the desired performance requirements. Subsequently, a nonlinear
control scheme is proposed to resolve the limitation of
sensitivity of the closed-loop system
to propagation delays.
The proposed strategy is based on a well-known input-output
feedback linearization approach that is shown to achieve an appreciable
improvement in the performance of the closed-loop unmanned network and
which is also less sensitive to the network propagation delays.