| 1. |
- Adaldo, Antonio, et al.
(författare)
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Cloud-Supported Formation Control of Second-Order Multiagent Systems
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2325-5870. ; 5:4, s. 1563-1574
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses a formation problem for a network of autonomous agents with second-order dynamics and bounded disturbances. Coordination is achieved by having the agents asynchronously upload (download) data to (from) a shared repository, rather than directly exchanging data with other agents. Well-posedness of the closed-loop system is demonstrated by showing that there exists a lower bound for the time interval between two consecutive agent accesses to the repository. Numerical simulations corroborate the theoretical results.
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| 2. |
- Blanchini, Franco, et al.
(författare)
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Aggregates of Monotonic Step Response systems : a structural classification
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - 2325-5870. ; 5:2, s. 782-792
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Tidskriftsartikel (refereegranskat)abstract
- Complex dynamical networks can often be analysed as the interconnection of subsystems, to simplify the model and better understand the global behaviour. Some biological networks can be analysed as aggregates of monotone subsystems. Yet, monotonicity is a strong requirement and relies on the knowledge of an explicit state model. Systems with a Monotonic Step Response (MSR), which include input-output monotone systems, are a broader class and have interesting features. The property of having a monotonically increasing step response can be evinced from experimental data. We consider networks that can be decomposed as aggregates of MSR subsystems and we provide a structural (parameter-free) classification of oscillatory and multistationary behaviours. The classification is based on the exclusive or concurrent presence of negative and positive cycles in the system $aggregate graph$, whose nodes are the MSR subsystems. The result is analogous to our earlier classification for aggregates of monotone subsystems. Our classification is applied to models of biomolecular networks and helps build synthetic biomolecular circuits that, by design, are well suited to exhibit the desired dynamics.
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| 3. |
- Demirel, Burak, et al.
(författare)
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Optimal Control of Linear Systems With Limited Control Actions : Threshold-Based Event-Triggered Control
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 2325-5870. ; 5:3, s. 1275-1286
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Tidskriftsartikel (refereegranskat)abstract
- We consider a finite-horizon linear-quadratic optimal control problem where only a limited number of control messages are allowed for sending from the controller to the actuator. To restrict the number of control actions computed and transmitted by the controller, we employ a threshold-based event-triggering mechanism that decides whether or not a control message needs to be calculated and delivered. Due to the nature of threshold-based event-triggering algorithms, finding the optimal control sequence requires minimizing a quadratic cost function over a nonconvex domain. In this paper, we first provide an exact solution to this nonconvex problem by solving an exponential number of quadratic programs. To reduce computational complexity, we then propose two efficient heuristic algorithms based on greedy search and the alternating direction method of multipliers technique. Later, we consider a receding horizon control strategy for linear systems controlled by event-triggered controllers, and we further provide a complete stability analysis of receding horizon control that uses finite-horizon optimization in the proposed class. Numerical examples testify to the viability of the presented design technique.
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| 4. |
- Du, Rong, et al.
(författare)
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On Maximizing Sensor Network Lifetime by Energy Balancing
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 2325-5870. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Many physical systems, such as water/electricity distribution networks, are monitored by battery-powered wireless-sensor networks (WSNs). Since battery replacement of sensor nodes is generally difficult, long-term monitoring can be only achieved if the operation of the WSN nodes contributes to long WSN lifetime. Two prominent techniques to long WSN lifetime are 1) optimal sensor activation and 2) efficient data gathering and forwarding based on compressive sensing. These techniques are feasible only if the activated sensor nodes establish a connected communication network (connectivity constraint), and satisfy a compressive sensing decoding constraint (cardinality constraint). These two constraints make the problem of maximizing network lifetime via sensor node activation and compressive sensing NP-hard. To overcome this difficulty, an alternative approach that iteratively solves energy balancing problems is proposed. However, understanding whether maximizing network lifetime and energy balancing problems are aligned objectives is a fundamental open issue. The analysis reveals that the two optimization problems give different solutions, but the difference between the lifetime achieved by the energy balancing approach and the maximum lifetime is small when the initial energy at sensor nodes is significantly larger than the energy consumed for a single transmission. The lifetime achieved by energy balancing is asymptotically optimal, and that the achievable network lifetime is at least 50% of the optimum. Analysis and numerical simulations quantify the efficiency of the proposed energy balancing approach.
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| 5. |
- Fontan, Angela, 1991-, et al.
(författare)
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Multiequilibria analysis for a class of collective decision-making networked systems
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - 2325-5870. ; :4, s. 1931-1940
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Tidskriftsartikel (refereegranskat)abstract
- The models of collective decision-making considered in this paper are nonlinear interconnected cooperative systems with saturating interactions. These systems encode the possible outcomes of a decision process into different steady states of the dynamics. In particular, they are characterized by two main attractors in the positive and negative orthant, representing two choices of agreement among the agents, associated to the Perron-Frobenius eigenvector of the system. In this paper we give conditions for the appearance of other equilibria of mixed sign. The conditions are inspired by Perron-Frobenius theory and are related to the algebraic connectivity of the network. We also show how all these equilibria must be contained in a solid disk of radius given by the norm of the equilibrium point which is located in the positive orthant.
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| 6. |
- Hajiesmaili, Mohammad Hassan, et al.
(författare)
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Multiperiod Network Rate Allocation With End-to-End Delay Constraints
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 2325-5870. ; 5:3, s. 1087-1097
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Tidskriftsartikel (refereegranskat)abstract
- QoS-aware networking applications such as real-time streaming and video surveillance systems require nearly fixed average end-to-end delay over long periods to communicate efficiently, although may tolerate some delay variations in short periods. This variability exhibits complex dynamics that makes rate control of such applications a formidable task. This paper addresses rate allocation for heterogeneous QoS-aware applications that preserves the long-term end-to-end delay constraint while seeking the maximum network utility cumulated over a fixed time interval. To capture the temporal dynamics of sources, we incorporate a novel time-coupling constraint in which delay sensitivity of sources is considered such that a certain end-to-end average delay for each source over a prespecified time interval is satisfied. We propose an algorithm, as a dual-based solution, which allocates source rates for the next time interval in a distributed fashion, given the knowledge of network parameters in advance. Also, we extend the algorithm to the case that the problem data is not known fully in advance to capture more realistic scenarios. Through numerical experiments, we show that our proposed algorithm attains higher average link utilization and a wider range of feasible scenarios in comparison with the best, to our knowledge, rate control schemes that may guarantee such constraints on delay.
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| 7. |
- Khong, Sei Zhen, et al.
(författare)
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Robust Synchronization in Multi-Agent Networks with Unstable Dynamics
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : IEEE. - 2325-5870. ; 5:1, s. 205-214
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Tidskriftsartikel (refereegranskat)abstract
- The problem of synchronization in heterogenous linear time-invariant networks is investigated. An approach blending the theory of integral quadratic constraints (IQCs) with the gap metric is proposed to study the problem within a unifying framework, where both the agents and communication channels can be dynamic, infinite-dimensional, unstable, and uncertain. Structural properties of the uncertainty are described by IQCs and exploited in the analysis to reduce conservatism. The homotopy employed in IQC analysis is defined with respect to the graph topology induced by the gap metric, whereby open-loop unstable dynamics are accommodated. Sufficient conditions for synchronism are provided, extending recent developments which have been shown to unify several existing synchronization analysis results in the literature.
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| 8. |
- Linsenmayer, Steffen, et al.
(författare)
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Event-Based Vehicle Coordination Using Nonlinear Unidirectional Controllers
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2325-5870. ; 5:4, s. 1575-1584
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a framework to control vehicle platoons with event-based communication and nonlinear controllers. The overall goal is to achieve a platoon that moves in a desired formation with a desired velocity and the convergence to this formation should be exponential while Zeno behavior has to be excluded. The set of admissible controllers for this problem is specified by the properties that they need to guarantee. These properties will be of a form such that they can be checked locally by every vehicle itself and heterogeneous controllers as well as heterogeneous possibly nonlinear dynamics of the vehicles in the platoon are allowed. The framework is shown to work with several communication networks and the set of networks will be characterized. Modifications that are necessary to cope with additive disturbances are described and a simulation example that shows the benefits of being able to use the framework in different networks is given.
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| 9. |
- Liuzza, Davide, et al.
(författare)
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Generalized PID Synchronization of Higher Order Nonlinear Systems With a Recursive Lyapunov Approach
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 2325-5870. ; 5:4, s. 1608-1621
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the problem of synchronization for nonlinear systems. Following a Lyapunov approach, we first study the global synchronization of nonlinear systems in the canonical control form with both distributed proportional-derivative and proportional-integral-derivative control actions of any order. To do so, we develop a constructive methodology and generate in an iterative way inequality constraints on the coupling matrices that guarantee the solvability of the problem or, in a dual form, provide the nonlinear weights on the coupling links between the agents such that the network synchronizes. The same methodology allows us to include a possible distributed integral action of any order to enhance the rejection of heterogeneous disturbances. The considered approach does not require any dynamic cancellation, thus preserving the original nonlinear dynamics of the agents. The results are then extended to linear and nonlinear systems admitting a canonical control transformation. Numerical simulations validate the theoretical results.
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| 10. |
- Pan, Wei, et al.
(författare)
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Identification of Nonlinear State-Space Systems from Heterogeneous Datasets
- 2018
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Ingår i: IEEE Transactions on Control of Network Systems. - : IEEE. - 2325-5870. ; 5:2, s. 737-747
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a new method to identify nonlinear state-space systems from heterogeneous datasets. The method is described in the context of identifying biochemical/gene networks (i.e., identifying both reaction dynamics and kinetic parameters) from experimental data. Simultaneous integration of various datasets has the potential to yield better performance for system identification. Data collected experimentally typically vary depending on the specific experimental setup and conditions. Typically, heterogeneous data are obtained experimentally through 1) replicate measurements from the same biological system or 2) application of different experimental conditions such as changes/perturbations in biological inductions, temperature, gene knock-out, gene over-expression, etc. We formulate here the identification problem using a Bayesian learning framework that makes use of “sparse group” priors to allow inference of the sparsest model that can explain the whole set of observed heterogeneous data. To enable scale up to large number of features, the resulting nonconvex optimization problem is relaxed to a reweighted Group Lasso problem using a convex-concave procedure. As an illustrative example of the effectiveness of our method, we use it to identify a genetic oscillator (generalized eight species repressilator). Through this example we show that our algorithm outperforms Group Lasso when the number of experiments is increased, even when each single time-series dataset is short. We additionally assess the robustness of our algorithm against noise by varying the intensity of process noise and measurement noise.
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