Karl H. Johansson

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—This paper considers a distributed control algorithm for frequency control of electrical power systems. We propose a distributed controller which retains the reference frequency of the buses under unknown load changes, while asymptotically minimizing a quadratic cost of power generation. For comparison, we also propose a centralized controller which also(More)
—This paper presents the work on resilient and secure power transmission and distribution developed within the VIKING (Vital Infrastructure, networKs, INformation and control system ManaGement) project. VIKING receives funding from the European Community's Seventh Framework Program. We will present the consortium, the motivation behind this research, the(More)
This paper investigates the problem of event-based control for the synchronization of networks of nonlinear dynamical agents. A distributed model based approach able to guarantee that all the agents converge to an adjustable synchronization region is derived. In such control scheme all the agents use a model of their neighborhood in order to generate(More)
We study hybrid systems from a global geometric perspective as piecewise smooth dynamical systems. Based on an earlier work, we define the notion of the hybrifold as a single piece-wise smooth state space reflecting the dynamics of the original system. Structural stability for hybrid systems is introduced and analyzed in this framework. In particular, it is(More)
We study the continuous-time consensus problem where nodes on a graph attempt to reach average consensus. We consider communication graphs that can be decomposed into a hierarchical structure and present a consensus scheme that exploits this hierarchical topology. The scheme consists of splitting the overall graph into layers of smaller connected subgraphs.(More)
Heating, Ventilation and Air Conditioning (HVAC) systems play a fundamental role in maintaining acceptable thermal comfort and air quality levels. Model Predictive Control (MPC) techniques are known to bring significant energy savings potential. Developing effective MPC-based control strategies for HVAC systems is nontrivial since buildings dynamics are(More)
We propose formal models for analyzing robustness of multi-hop control networks, where data from sensors to controllers and from controllers to actuators is sent through a multi-hop communication network subject to disruptions. When communication disruptions are long, compared to the speed of the control system, we propose to model them as permanent link(More)
We propose a novel analytical model to study fragmentation methods in wireless sensor networks adopting the Constrained Application Protocol (CoAP) and the IEEE 802.15.4 standard for medium access control (MAC). The blockwise transfer technique proposed in CoAP and the 6LoWPAN fragmentation are included in the analysis. The two techniques are compared in(More)
A conventional way to handle model predictive control (MPC) problems distributedly is to solve them via dual decomposition and gradient ascent. However, at each time-step, it might not be feasible to wait for the dual algorithm to converge. As a result, the algorithm might be needed to be terminated prematurely. One is then interested to see if the solution(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Abstract— It is desirable to limit the amount of communication and(More)