3,577 research outputs found
Feedback Control Goes Wireless: Guaranteed Stability over Low-power Multi-hop Networks
Closing feedback loops fast and over long distances is key to emerging
applications; for example, robot motion control and swarm coordination require
update intervals of tens of milliseconds. Low-power wireless technology is
preferred for its low cost, small form factor, and flexibility, especially if
the devices support multi-hop communication. So far, however, feedback control
over wireless multi-hop networks has only been shown for update intervals on
the order of seconds. This paper presents a wireless embedded system that tames
imperfections impairing control performance (e.g., jitter and message loss),
and a control design that exploits the essential properties of this system to
provably guarantee closed-loop stability for physical processes with linear
time-invariant dynamics. Using experiments on a cyber-physical testbed with 20
wireless nodes and multiple cart-pole systems, we are the first to demonstrate
and evaluate feedback control and coordination over wireless multi-hop networks
for update intervals of 20 to 50 milliseconds.Comment: Accepted final version to appear in: 10th ACM/IEEE International
Conference on Cyber-Physical Systems (with CPS-IoT Week 2019) (ICCPS '19),
April 16--18, 2019, Montreal, QC, Canad
Distributed Robust Consensus Control of Multi-agent Systems with Heterogeneous Matching Uncertainties
This paper considers the distributed consensus problem of linear multi-agent
systems subject to different matching uncertainties for both the cases without
and with a leader of bounded unknown control input. Due to the existence of
nonidentical uncertainties, the multi-agent systems discussed in this paper are
essentially heterogeneous. For the case where the communication graph is
undirected and connected, a distributed continuous static consensus protocol
based on the relative state information is first designed, under which the
consensus error is uniformly ultimately bounded and exponentially converges to
a small adjustable residual set. A fully distributed adaptive consensus
protocol is then designed, which, contrary to the static protocol, relies on
neither the eigenvalues of the Laplacian matrix nor the upper bounds of the
uncertainties. For the case where there exists a leader whose control input is
unknown and bounded, distributed static and adaptive consensus protocols are
proposed to ensure the boundedness of the consensus error. It is also shown
that the proposed protocols can be redesigned so as to ensure the boundedness
of the consensus error in the presence of bounded external disturbances which
do not satisfy the matching condition. A sufficient condition for the existence
of the proposed protocols is that each agent is stabilizable.Comment: 16 page, 10 figures. This manuscript is an extended version of our
paper accepted for publication by Automatic
On Robust Synchronization of Nonlinear Systems with Application to Grid Integration of Renewable Energy Sources
International audienceMany systems in the natural and physical world often work in unison with similar other systems. This process of simultaneous operation is known as synchronization. In the past few decades, owing to this phenomenon's importance, extensive research efforts have been made. However, many of the existing results consider the systems are identical and/or linear time-invariant, while practical systems are often nonlinear and nonidentical for various reasons. This observation motivated several recent studies on the synchronization of nonidentical (i.e., heterogeneous) nonlinear systems. This paper summarizes some recent results on the synchronization of heterogeneous nonlinear systems, as developed in the thesis [1]. First, the results on the synchronization of a particular class of robustly stable nonlinear systems are presented. Then, these results are applied to an example model known as Brockett oscillator. Finally, using the Brockett oscillator as a common dynamics, output oscillatory synchronization results are given for heterogeneous nonlinear systems of relative degree 2 or higher. An application example of Brockett oscillator for power-grid synchronization is also presented. Some outlooks are provided regarding future research directions
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