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Decentralised and scalable conditions for robust stability of networks of heterogenous linear time-invariant (LTI) systems are derived based on integral quadratic constraints. These generalise previous works in the literature with an increased flexibility in the choice of multipliers employed. The results allow for arbitrary interconnection matrices and accommodate multi-input-multi-output systems
To fulfill increasing requirements in the manufacturing sector, companies are faced with several challenges. Three major challenges have been identified regarding time-to-market, vertical feedback loops and level of automation. Grafchart, a graphical language aimed for supervisory control applications, can be used from the process-planning phase, through the implementation phase and all the way to
When a feedback controller is implemented in a networked embedded system, the computations and communications induce delays and jitter, which may destabilize the control loop. The majority of previous work on analysis of control loops with time-varying delays has focused on output (actuation) jitter. In many embedded systems, input (sampling) jitter is also an issue. In this paper, we analyze the
We consider a wind power plant of megawatt wind turbines operating in derated mode. When operating in this mode, the wind power plant controller is free to distribute power set-points to the individual turbines, as long as the total power demand is met. In this work, we design a controller that exploits this freedom to reduce the fatigue on the turbines in the wind power plant. We show that the co
Advances in Intelligent Transport Systems (ITS), intelligent vehicles and cooperative systems are enabling traffic and transport solutions that are both safer and more environmentally acceptable. While it is well known that high dependability is a desirable feature it has a price, and the level of dependability needed varies from application to application. Typical examples are cooperative safety
Three approaches of iterative learning control (ILC) applied to a Gantry-Tau parallel kinematic robot aC algorithms using 1) measured motor angles, 2) tool-position estimates, and for evaluation purposes, 3l position. The approaches are compared experimentally, with the tool performance evaluated using extert is concluded that the tool performance can be improved using tool-position estimates in t
In this paper an order reduction method for spatially distributed models is presented. Such systems may be modeled as two nodes interacting with each other through feedback. A model of one of the nodes reduced in such a way, that the closed loop performance is approximated. The method exploits a coprime factor description of the closed loop model and semidefinite programming. The method is related
Clock synchronization is a necessary component in modern distributed systems, especially WSN. Despite the great effort and the numerous improvements, the existing synchronization schemes do not yet address the cancellation of propagation delays. Up to a few years ago, this was not perceived as a problem, because the time-stamping precision was a more limiting factor for the accuracy achievable wit
The PID controller is the most common controller and it is taught in most introductory automatic control courses. To develop an intuitive understanding of the basic concepts of the PID controller and PID parameter tuning, interactive and freely available tools are important. A PID module for educational purposes has been implemented in JGrafchart, a freely available development environment for the
We define the notion of convex-monotone system and prove that for such systems the state trajectory x(⋅) is a convex function of the initial state x(0) and the input trajectory u(⋅). This observation gives a useful class of nonlinear dynamical systems for which control design can be performed by convex optimization. Applications to evolutionary dynamics of diseases and voltage stability in power n
This technical note investigates the model reduction problem for mean square stable discrete time Markov jump linear systems. For this class of systems a balanced truncation algorithm is developed. The reduced order model is suboptimal, however the approximation error, which is captured by means of the stochastic L2 gain, is bounded from above by twice the sum of singular numbers associated to the
Stability of Wardrop equilibria is analyzed for dynamical transportation networks in which the drivers' route choices are influenced by information at multiple temporal and spatial scales. The considered model involves a continuum of indistinguishable drivers commuting between a common origin/destination pair in an acyclic transportation network. The drivers' route choices are affected by their, r
With larger penetrations of wind power, the uncertainty increases in power systems operations. The wind power forecast errors must be accounted for by adapting existing operating tools or designing new ones. A switch from the deterministic framework used today to a probabilistic one has been advocated. This two-part paper presents a framework for risk-based operations of power systems. This framew
Operating criteria for power systems, such as theN−1-criterion, are often based on evaluating whether the system is vulnerable to a specific set of contingencies. Therefore, a major part of power system security is concerned with establishing regions in parameter space where the system is vulnerable to specific contingencies. In this article we exploit the possibility of using Monte Carlo simulati
The problem of modeling and controlling re- sources in a system with interaction between hardware and software is considered. A model encompassing both hardware and software dynamics is developed together with an on- line estimation scheme in order reduce dependence on a- priori information. A control structure is presented in order to control performance under constrained resource situations and
