Publications
685 results found
Jiang J, Di Franco P, Astolfi A, 2016, Shared control for the kinematic and dynamic models of a mobile robot, IEEE Transactions on Control Systems Technology, Vol: 24, Pages: 2112-2124, ISSN: 1063-6536
This paper presents shared-control algorithms for the kinematic and dynamic models of a mobile robot with a feasible configuration set defined by means of linear inequalities. The shared-control laws based on a hysteresis switch are designed in the case in which absolute positions are not available. Instead, we measure the distances to obstacles and angular differences. Formal properties of the closed-loop systems with the shared control are established by a Lyapunov-like analysis. Simulation results and experimental results are presented to show the effectiveness of the algorithm.
Carnevale D, Galeani S, Sassano M, et al., 2016, Robust hybrid estimation and rejection of multi-frequency signals, International Journal of Adaptive Control and Signal Processing, Vol: 30, Pages: 1649-1673, ISSN: 1099-1115
We consider the problem of output regulation for LTI systems in the presence of unknown exosystems. The knowledge about the multi-frequency signals exosystem consists in the maximum number of frequencies and their maximal value. The control scheme relies on two main components: an estimation algorithm, to reconstruct the signal generated by the exosystem, and a controller, to enforce the output regulation property to the closed-loop system. To tackle the first task, we propose a hybrid observer for the estimation of the (possibly piece-wise continuous) number and values of the frequencies contained in the exogenous signal. The hybrid observer is particularly appealing for numerical implementations, and it is combined with a self-tuning algorithm of the free parameters (gains), thus improving its performance even in case of noisy measurements. Semi-global exponential convergence of the estimation error is provided. As far as the second task is concerned, a robust hybrid regulator is designed for practical rejection of the multi-frequency disturbance signal acting on the plant. The result is achieved by exploiting the frequencies estimated by the hybrid observer. The effectiveness of the proposed control scheme is shown by means of numerical simulations.
Jiang J, Astolfi A, 2016, Shared-Control for Typical Driving Scenarios, European Control Conference
Sassano M, Astolfi A, 2016, Approximate Dynamic Tracking and Feedback Linearization, 55th IEEE Conference on Decision and Control (CDC), Publisher: IEEE, Pages: 5688-5693, ISSN: 0743-1546
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- Citations: 4
Elliott ADT, Caccia A, Thomas A, et al., 2016, Shared inductor hybrid topology for weight constrained piezoelectric actuators, 16th International Conference on Micro- and Nano-Technology for Power Generation and Energy Conversion Applications (PowerMEMS), Publisher: IOP PUBLISHING LTD, ISSN: 1742-6588
Ascencio P, Astolfi A, Parisini T, 2016, An Adaptive Observer for a class of Parabolic PDEs based on a Convex Optimization Approach for Backstepping PDE Design, American Control Conference (ACC), Publisher: IEEE, Pages: 3429-3434, ISSN: 0743-1619
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- Citations: 4
Padoan A, Astolfi A, 2015, Dimension estimation for autonomous nonlinear systems, 54th IEEE Conference on Decision and Control, Publisher: IEEE, Pages: 103-108
The problem of estimating the dimension of the state-space of an autonomous nonlinear system is considered. Assuming that sampled measurements of the output and finitely many of its time derivatives are available, an exhaustive search algorithm able to retrieve the dimension of the minimal state-space realization is proposed. The performance of the algorithm are evaluated on specific nonlinear systems.
Padoan A, Astolfi A, 2015, Towards deterministic subspace identification for autonomous nonlinear systems, 54th IEEE Conference on Decision and Control, Publisher: IEEE, Pages: 127-132
The problem of identifying deterministic autonomous linear and nonlinear systems is studied. A specific version of the theory of deterministic subspace identification for discrete-time autonomous linear systems is developed in continuous time. By combining the subspace approach to linear identification and the differential-geometric approach to nonlinear control systems, a novel identification framework for continuous-time autonomous nonlinear systems is developed.
Jiang J, Astolfi A, 2015, State and output-feedback shared-control for a class of linear constrained systems, IEEE Transactions on Automatic Control, Vol: 61, Pages: 3209-3214, ISSN: 0018-9286
This paper presents state and output feedback sharedcontrol algorithms for a class of linear systems in the presence of constraints on the output described by means of linear inequalities. The properties of the closed-loop shared-control systems are studied using Lyapunov arguments. Simulation results demonstrate the effectiveness of the algorithm.
Scarciotti G, Astolfi A, 2015, Model reduction for nonlinear systems and nonlinear time-delay systems from input/output data, 2015 54th IEEE Conference on Decision and Control (CDC), Publisher: IEEE, Pages: 7298-7303, ISSN: 0743-1546
Jiang J, Astolfi A, 2015, Shared-Control for a UAV Operating in the 3D Space, European Control Conference 2015, Publisher: IEEE
This paper presents a shared-control scheme for a UAV moving in a 3D space while its feasible Cartesian position set is defined by a group of linear inequalities. A hysteresis switch is used to combine the human input and the feedback control input based on the definitions of a safe set, a hysteresis set and a “dangerous” set. Case studies given in the paper show the effectiveness of the shared-control algorithm.
Ionescu TC, Astolfi A, 2015, Nonlinear moment matching-based model order reduction, IEEE Transactions on Automatic Control, Vol: 61, Pages: 2837-2847, ISSN: 0018-9286
In this paper we present a time-domain notion of moments for a class of single-input, single-output nonlinear systems in terms of the evolution of the output of a generalized signal generator driven by the nonlinear system. We also define a new notion of moment matching and present a family of (nonlinear) parametrized reduced order models that achieve moment matching. We establish relations with existing notions of moment for nonlinear systems, showing that the newly derived and the existing families of reduced order models that achieve nonlinear moment matching, respectively, are equivalent. Furthermore, we compute the reduced order model that matches the moments at two chosen signal generators (one exciting the input of the system and another driven by the system), simultaneously. We also present a family of models computed on the basis of a nonlinear extension of the Petrov-Galerkin projection that achieve moment matching. Finally, we specialize the results to the case of nonlinear, input-affine systems.
Scarciotti G, Astolfi A, 2015, Model reduction for linear systems and linear time-delay systems from input/output data, 2015 European Control Conference (ECC), Publisher: IEEE, Pages: 334-339
An algorithm for the estimation of the moments of linear systems and linear time-delay systems from input/output data is proposed. The estimate, which converges to the moments of the system, is exploited to construct a family of reduced order models. These models asymptotically match the moments of the unknown system to be reduced. The computational complexity of the algorithm is analyzed and the use of the algorithm is illustrated by a benchmark example.
Scarciotti G, Astolfi A, 2015, Model reduction by matching the steady-state response of explicit signal generators, IEEE Transactions on Automatic Control, Vol: 99, ISSN: 1558-2523
Padoan A, Astolfi A, 2015, A Note on Delay Coordinates for Locally Observable Analytic Systems, IEEE Transactions on Automatic Control, Vol: 61, Pages: 1409-1412, ISSN: 1558-2523
In this short note, the problem of locally reconstructing the state of a nonlinear system is studied. To avoid computational difficulties arising in the numerical differentiation of the output, the so-called delay coordinates are considered. The assumptions of analyticity and (local) observability of the system are shown to imply that a family of mappings, induced by the delay coordinates and parameterized by a time delay parameter, gives a local diffeomorphism for generic values of such delay parameter on a certain set. A worked-out example illustrates the result.
Nunna K, Sassano M, Astolfi A, 2015, Constructive interconnection and damping assignment for port-controlled Hamiltonian systems, IEEE Transactions on Automatic Control, Vol: 60, Pages: 2350-2361, ISSN: 0018-9286
The Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC) problem for port-controlled Hamiltonian systems is revisited. We propose a methodology that exploits the novel notion of algebraic solution of the so-called matching equation. This notion is instrumental for the construction of an energy function, defined on an extended state-space, which does not rely upon the solution of any partial differential equation. This yields, differently from the classical solution, a dynamic state feedback that stabilizes a desired equilibrium point. In addition, conditions that allow to preserve the port-controlled Hamiltonian structure in the extended closed-loop system are provided. The theory is validated on two physical systems: the magnetic levitated ball and a third order food-chain system. A dynamic control law is constructed for both these systems by assigning a damping factor that cannot be assigned by the classical IDA-PBC.
Jiang J, Astolfi A, 2015, Shared-control for the kinematic model of a rear-wheel drive car, American Control Conference, Publisher: IEEE, Pages: 1155-1160, ISSN: 0743-1619
This paper presents a shared-control algorithm for the kinematic model of a rear-wheel drive car, for which the set of feasible Cartesian positions is defined by a group of linear inequalities. The shared-control scheme is based on a hysteresis switch and its properties are established by a Lyapunov-like analysis. Simple numerical examples demonstrate the effectiveness of the shared-control law.
Scarciotti G, Astolfi A, 2015, Model reduction of neutral linear and nonlinear time-invariant time-delay systems with discrete and distributed delays, IEEE Transactions on Automatic Control, Vol: 99, ISSN: 1558-2523
The problem of model reduction by moment matching for linear and nonlinear differential time-delay systems is studied. The class of models considered includes neutral differential time-delay systems with discrete-delays and distributeddelays. The description of moment is revisited by means of a Sylvester-like equation for linear time-delay systems and by means of the center manifold theory for nonlinear time-delay systems. In addition the moments at infinity are characterized for both linear and nonlinear time-delay systems. Parameterized families of models achieving moment matching are given. The parameters can be exploited to derive delay-free reduced order models or time-delay reduced order models with additional properties, e.g. interpolation at an arbitrary large number of points. Finally, the problem of obtaining a reduced order model of an unstable system is discussed and solved.
Mylvaganam T, Astolfi A, 2015, Control of Microgrids Using a Differential Game Theoretic Framework, Conference on Decision and Control
Mylvaganam T, Astolfi A, 2015, A differential game approach to formation control for a team of agents with one leader, American Control Conference
Scarciotti G, Praly L, Astolfi A, 2015, Invariance-like theorems and “lim inf” convergence properties, IEEE Transactions on Automatic Control, Vol: 61, Pages: 648-661, ISSN: 1558-2523
Several theorems, inspired by the Krasovskii-LaSalle invariance principle, to establish “lim inf” convergence results are presented in a unified framework. These properties are useful to “describe” the oscillatory behavior of the solutions of dynamical systems. The theorems resemble “lim inf” Matrosov and Small-gain theorems and are based on a “lim inf” Barbalat's Lemma. Additional technical assumptions to have “lim” convergence are given: the “lim inf”/“lim” relation is discussed in-depth and the role of some of the assumptions is illustrated by means of examples.
Mylvaganam T, Sassano M, Astolfi A, 2015, Constructive epsilon-nash equilibria for nonzero-sum differential games, IEEE Transactions on Automatic Control, Vol: 60, Pages: 950-965, ISSN: 0018-9286
In this paper, a class of infinite-horizon, nonzero-sum differential games and their Nash equilibria are studied and the notion of ε α -Nash equilibrium strategies is introduced. Dynamic strategies satisfying partial differential inequalities in place of the Hamilton-Jacobi-Isaacs partial differential equations associated with the differential games are constructed. These strategies constitute (local) ε α -Nash equilibrium strategies for the differential game. The proposed methods are illustrated on a differential game for which the Nash equilibrium strategies are known and on a Lotka-Volterra model, with two competing species. Simulations indicate that both dynamic strategies yield better performance than the strategies resulting from the solution of the linear-quadratic approximation of the problem.
Jiang J, Astolfi A, 2015, Shared-control for the kinematic model of a mobile robot, IEEE 53rd Annual Conference on Decision and Control (CDC), Publisher: IEEE, Pages: 62-67
This paper presents a shared-control algorithm for the kinematic model of a mobile robot. The set of feasible position of the robot is defined by a group of linear inequalities. The shared-control strategy is based on a hysteresis switch and its properties are established by a Lyapunov-like analysis. Simulation results illustrate the effectiveness of the algorithm
Chang HJ, Astolfi A, 2015, Immune response enhancement strategy via hybrid control perspective, Pages: 1-26, ISSN: 0302-9743
We investigate a control method for disease dynamics, such as HIV and malaria, to boost the immune response using a model-based approach. In particular we apply the control method to select the appropriate immune response between Th1 and Th2 responses. The idea of state jump is introduced and discussed based on hybrid control systems. To implement the control idea we propose physically available methods for each biological system. The studies on malaria model and HIV model are supported by experimental data.
Scarciotti G, Astolfi A, 2015, Characterization of the moments of a linear system driven by explicit signal generators, American Control Conference, Publisher: IEEE, Pages: 589-594, ISSN: 0743-1619
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- Citations: 18
Ascencio P, Astolfi A, Parisini T, 2015, Backstepping PDE Design, Volterra and Fredholm Operators: a Convex Optimization Approach, 54th IEEE Conference on Decision and Control (CDC), Publisher: IEEE, Pages: 7048-7053, ISSN: 0743-1546
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- Citations: 3
Scarciotti G, Astolfi A, 2014, Model reduction by moment matching for nonlinear time-delay systems, Pages: 3642-3647
Schiffer J, Ortega R, Astolfi A, et al., 2014, Conditions for stability of droop-controlled inverter-based microgrids, Automatica, Vol: 50, Pages: 2457-2469, ISSN: 0005-1098
We consider the problem of stability analysis for droop-controlled inverter-based microgrids with meshed topologies. The inverter models include variable frequencies as well as voltage amplitudes. Conditions on the tuning gains and setpoints for frequency and voltage stability, together with desired active power sharing, are derived in the paper. First, we prove that for all practical choices of these parameters global boundedness of trajectories is ensured. Subsequently, assuming the microgrid is lossless, a port-Hamiltonian description is derived, from which sufficient conditions for stability are given. Finally, we propose for generic lossy microgrids a design criterion for the controller gains and setpoints such that a desired steady-state active power distribution is achieved. The analysis is validated via simulation on a microgrid based on the CIGRE (Conseil International des Grands Réseaux Electriques) benchmark medium voltage distribution network.
Chang H, Krieger A, Astolfi A, et al., 2014, Robust multi-parametric model predictive control for LPV systems with application to anaesthesia, JOURNAL OF PROCESS CONTROL, Vol: 24, Pages: 1538-1547, ISSN: 0959-1524
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- Citations: 12
Chang HJ, Moog CH, Astolfi A, et al., 2014, A control systems analysis of HIV prevention model using impulsive input, BIOMEDICAL SIGNAL PROCESSING AND CONTROL, Vol: 13, Pages: 123-131, ISSN: 1746-8094
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- Citations: 18
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