| 1. |
- Adaldo, Antonio, 1989-, et al.
(author)
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Control of Multi-Agent Systems with Event-Triggered Cloud Access
- 2015
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In: Proceedings of the 14th annual European Control Conference. - : IEEE. - 9783952426937 ; , s. 954-961
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Conference paper (peer-reviewed)abstract
- This paper investigates a multi-agent formation control problem with event-triggered control updates and additive disturbances. The agents communicate only by exchanging information in a cloud repository. The communication with the cloud is considered a shared and limited resource, and therefore it is used intermittently and asynchronously by the agents. The proposed approach takes advantage of having a shared asynchronous cloud support while guaranteeing a reduced number of communication. More in detail, each agent schedules its own sequence of cloud accesses in order to achieve a coordinated network goal. A control law is given with a criterion for scheduling the control updates recursively. The closed loop scheme is proven to be effective in achieving the control objective and a numerical simulation corroborates the theoretical results.
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| 2. |
- Biel, Martin, et al.
(author)
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SiMpLIfy : A toolbox for structured model reduction
- 2015
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In: 2015 European Control Conference, ECC 2015. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426937 ; , s. 1159-1164
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Conference paper (peer-reviewed)abstract
- In this paper, we present a toolbox for structured model reduction developed for MATLAB. In addition to structured model reduction methods using balanced realizations of the subsystems, we introduce a numerical algorithm for structured model reduction using a subgradient optimization algorithm. We briefly present the syntax for the toolbox and its features. Finally, we demonstrate the applicability of various model reduction methods in the toolbox on a structured mass-spring mechanical system.
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| 3. |
- Boem, F., et al.
(author)
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A distributed pareto-optimal dynamic estimation method
- 2015
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In: 2015 European Control Conference, ECC 2015. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426937 ; , s. 3673-3680
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Conference paper (peer-reviewed)abstract
- In this paper, a novel distributed model-based prediction method is proposed using sensor networks. Each sensor communicates with the neighboring nodes for state estimation based on a consensus protocol without centralized coordination. The proposed distributed estimator consists of a consensus-filtering scheme, which uses a weighted combination of sensors information, and a model-based predictor. Both the consensus-filtering weights and the model-based prediction parameter for all the state components are jointly optimized to minimize the variance and bias of the prediction error in a Pareto framework. It is assumed that the weights of the consensus-filtering phase are unequal for the different state components, unlike consensus-based approaches from literature. The state, the measurements, and the noise components are assumed to be individually correlated, but no probability distribution knowledge is assumed for the noise variables. The optimal weights are derived and it is established that the consensus-filtering weights and the model-based prediction parameters cannot be designed separately in an optimal way. The asymptotic convergence of the mean of the prediction error is demonstrated. Simulation results show the performance of the proposed method, obtaining better results than distributed Kalman filtering.
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| 4. |
- Carli, Ruggero, et al.
(author)
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Distributed quadratic programming under Asynchronous and Lossy Communications via Newton-Raphson Consensus
- 2015
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In: 2015 European Control Conference (ECC). - Piscataway, NJ : IEEE Communications Society. - 9783952426937 ; , s. 2514-2520
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Conference paper (peer-reviewed)abstract
- Quadratic optimization problems appear in several interesting estimation, learning and control tasks. To solve these problems in peer-to-peer networks it is necessary to design distributed optimization algorithms supporting directed, asynchronous and unreliable communication. This paper addresses this requirement by extending a promising distributed convex optimization algorithm, known as Newton-Raphson consensus, and originally designed for static and undirected communication. Specifically, we modify this algorithm so that it can cope with asynchronous, broadcast and unreliable lossy links, and prove that the optimization strategy correctly converge to the global optimum when the local cost functions are quadratic. We then support the intuition that this robustified algorithm converges to the true optimum also for general convex problems with dedicated numerical simulations.
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| 5. |
- Dabiri, Azita, 1984, et al.
(author)
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Distributed LPV State-Feedback Control with Application to Motorway Ramp Metering
- 2015
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In: In proceedings of European Control Conference, ECC’15, July 15-17, Linz, Austria. - 9783952426937 ; , s. 1480-1485
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Conference paper (peer-reviewed)abstract
- In this paper, we develop a distributed state-feedbackcontroller synthesis algorithm for a discrete-time LPVsystem that is composed of the interconnection of severalsubsystems each scheduled by its own parameters. A set ofLMI conditions are derived for robust L2-gain performanceof such a system in the framework of multiplier-based LPVsynthesis. The results have been oriented to be applied intraffic flow control in motorways by ramp metering. First,with the use of a proper transformation, the nonlineartraffic flow model has been represented as theinterconnection of LPV subsystems. Then the developedsynthesis results have been used to design a gain-scheduleddistributed state-feedback controller that keeps thedensity of all segments around a desired value by the useof ramp metering.
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| 6. |
- Demirel, Burak, et al.
(author)
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To wait or to drop : On the optimal number of retransmissions in wireless control
- 2015
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In: 2015 European Control Conference, ECC 2015. - : IEEE. - 9783952426937 ; , s. 962-968
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Conference paper (peer-reviewed)abstract
- The dimensioning of wireless communication protocols for networked control involves a non-trivial trade-off between reliability and delay. Due to the lossy nature of wireless communications, there is a risk that sensor messages will be dropped. The end-to-end reliability can be improved by retransmitting dropped messages, but this comes at the expense of additional delays. In this work, we determine the number of retransmissions that strikes the optimal balance between communication reliability and delay, in the sense that it achieves the minimal expected linear-quadratic loss of the closed-loop system. An important feature of our setup is that it accounts for the random delays and possible losses that occur when unreliable communication is combatted with retransmissions. The resulting controller dynamically switches among a set of infinite-horizon linear-quadratic regulators, and is simple to implement. Numerical simulations are carried out to highlight the trade-off between reliability and delay.
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| 7. |
- Ebadat, Afrooz, et al.
(author)
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Blind identification strategies for room occupancy estimation
- 2015
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In: 2015 European Control Conference (ECC). - Piscataway, NJ : IEEE Communications Society. - 9783952426937 ; , s. 1315-1320
-
Conference paper (peer-reviewed)abstract
- We propose and test on real data a two-tier estimation strategy for inferring occupancy levels from measurements of CO2 concentration and temperature levels. The first tier is a blind identification step, based either on a frequentist Maximum Likelihood method, implemented using non-linear optimization, or on a Bayesian marginal likelihood method, implemented using a dedicated Expectation-Maximization algorithm. The second tier resolves the ambiguity of the unknown multiplicative factor, and returns the final estimate of the occupancy levels. The overall procedure addresses some practical issues of existing occupancy estimation strategies. More specifically, first it does not require the installation of special hardware, since it uses measurements that are typically available in many buildings. Second, it does not require apriori knowledge on the physical parameters of the building, since it performs system identification steps. Third, it does not require pilot data containing measured real occupancy patterns (i.e., physically counting people for some periods, a typically expensive and time consuming step), since the identification steps are blind.
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| 8. |
- Karlsson, Fredrik, et al.
(author)
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Sensor Fused Indoor Positioning Using Dual Band WiFi Signal Measurements
- 2015
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In: 2015 European Control Conference (ECC). - 9783952426937 ; , s. 1669-1672
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Conference paper (peer-reviewed)abstract
- In this paper, signal strengths from known WiFi access points are used together with a particle filter to perform indoor navigation. It is shown that more information is obtained by using signals of both 2.4 and 5.0 GHz, compared to using only one frequency. Thus, using both frequencies provides a more accurate positioning. The second contribution is an algorithm where WiFi measurements are combined with pedestrian dead reckoning (PDR), which is based on step counting using an accelerometer and hypotheses of the heading using a gyroscope. This was found to provide further accuracy compared to more conventional methods.
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| 9. |
- Katselis, D., et al.
(author)
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On experiment design for single carrier and multicarrier systems
- 2015
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In: 2015 European Control Conference, ECC 2015. - : Institute of Electrical and Electronics Engineers (IEEE). - 9783952426937 ; , s. 1772-1777
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Conference paper (peer-reviewed)abstract
- In this paper, the problem of experiment design in single input single output (SISO) single carrier (SC) systems under a deterministic channel assumption is investigated and several connections with optimal preamble designs in multicarrier (MC) systems are established. In the context of SC systems, we derive optimal input sequences for the least-squares (LS) channel estimator under an input energy constraint. We then establish certain connections to optimal input designs for LS frequency domain channel estimation in MC systems. These connections reflect similarities between SC and MC systems both quantitative, i.e., in the achievable mean square error (MSE) performance, as well as qualitative, i.e., in the actual optimal input sequences. Simulations are provided to support the derived results.
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| 10. |
- Khong, Sei Zhen, et al.
(author)
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Robust Feedback Stability of Negative Imaginary Systems: An Integral Quadratic Constraint Approach
- 2015
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In: 2015 European Control Conference (ECC). - 9783952426937
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Conference paper (peer-reviewed)abstract
- Sufficient conditions for stability of feedback interconnections of negative imaginary systems are derived via an integral quadratic constraint (IQC) approach. These extend existing results in the literature by exploiting the flexibility present at the static and infinite frequencies to reduce conservatism. Negative imaginary transfer functions with poles on the imaginary axis are accommodated using a recently generalised IQC-based robustness result. In particular, the negative imaginary property of systems is shown to give rise to IQCs on positive frequencies that are bounded away from zero and infinity. Additional quadratic conditions are introduced to take care of the IQCs near the DC and instantaneous gains of the systems.
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