50,241 research outputs found
Convex conditions on decentralized control for graph topology preservation
International audienceThe paper focuses on the preservation of a given graph topology which is usually chosen to ensure its connectivity. This is an essential ingredient allowing interconnected systems to accomplish tasks by using decentralized control strategies. We consider a networked system with discrete-time dynamics in which the subsystems are able to communicate if an algebraic relation between their states is satisfied. Each subsystem is called agent and the connected subsystems are called neighbors. The agents update their state in a decentralized manner by taking into account the neighbors' states. The characterization of the local control feedback gains ensuring topology preservation is provided. The results are based on invariance and set-theory and yield to conditions in Linear Matrix Inequality (LMI) form. The conditions for topology preservation are applied to an illustrative example concerning partial state consensus of agents with double integrator dynamics
Locally Optimal Estimation and Control of Cable Driven Parallel Robots using Time Varying Linear Quadratic Gaussian Control
We present a locally optimal tracking controller for Cable Driven Parallel
Robot (CDPR) control based on a time-varying Linear Quadratic Gaussian (TV-LQG)
controller. In contrast to many methods which use fixed feedback gains, our
time-varying controller computes the optimal gains depending on the location in
the workspace and the future trajectory. Meanwhile, we rely heavily on offline
computation to reduce the burden of online implementation and feasibility
checking. Following the growing popularity of probabilistic graphical models
for optimal control, we use factor graphs as a tool to formulate our controller
for their efficiency, intuitiveness, and modularity. The topology of a factor
graph encodes the relevant structural properties of equations in a way that
facilitates insight and efficient computation using sparse linear algebra
solvers. We first use factor graph optimization to compute a nominal
trajectory, then linearize the graph and apply variable elimination to compute
the locally optimal, time varying linear feedback gains. Next, we leverage the
factor graph formulation to compute the locally optimal, time-varying Kalman
Filter gains, and finally combine the locally optimal linear control and
estimation laws to form a TV-LQG controller. We compare the tracking accuracy
of our TV-LQG controller to a state-of-the-art dual-space feed-forward
controller on a 2.9m x 2.3m, 4-cable planar robot and demonstrate improved
tracking accuracies of 0.8{\deg} and 11.6mm root mean square error in rotation
and translation respectively.Comment: 8 pages, 11 figures, accepted to IEEE International Conference on
Intelligent Robotics and Systems (IROS) 202
Distributed Consensus of Linear Multi-Agent Systems with Switching Directed Topologies
This paper addresses the distributed consensus problem for a linear
multi-agent system with switching directed communication topologies. By
appropriately introducing a linear transformation, the consensus problem is
equivalently converted to a stabilization problem for a class of switched
linear systems. Some sufficient consensus conditions are then derived by using
tools from the matrix theory and stability analysis of switched systems. It is
proved that consensus in such a multi-agent system can be ensured if each agent
is stabilizable and each possible directed topology contains a directed
spanning tree. Finally, a numerical simulation is given for illustration.Comment: The paper will be presented at the 2014 Australian Control Conference
(AUCC 2014), Canberra, Australi
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