1,721,205 research outputs found
A Robust Anti-Windup Scheme for Manual Flight Control of an Unstable Aircraft
No full textA result on robust-in-the-large antiwindup compensation obtained for the case of asymptotically stable systems is extended to deal with unstable plants with asymptotically null references. The use of a weakened formulation of the antiwindup problem is crucial in the achievement of robustness to large parameter variations. The proposed design approach results in an antiwindup compensator that works as an add-on for any a priori given, high-performance controller, synthesized without taking saturation or robustness issues into account. The technique is applied to a reduced, short-period dynamic model of a highly unstable fighter aircraft, a case in which the issues of control saturation during aggressive maneuvering and robustness with respect to large parameter variations are of paramount importance. Simulations in low- and high-speed regimes demonstrate that the weakened antiwindup compensator outperforms previous antiwindup techniques in providing robust stability to the closed-loop system while exploiting the available control power in all of the considered maneuvers
Distributed Endogenous Internal Model for Modal Consensus and Formation Control
No full textIn this paper, the problems of (modal) consensus and formation control are tackled for a group of heterogeneous agents described by linear dynamics and communicating over a network with fixed topology. The classic approach to these problems prescribes that each agent is provided with its own complete internal model of the desired dynamics (which can be viewed as an exosystem). In this paper, the novel concept of Distributed Endogenous Internal Model is introduced and discussed. Such internal model is characterized by two features: i) it is actually distributed over the network, i.e. no single agent is provided with a complete internal model; ii) it is endogenous, namely it is generated by exploiting the dynamics already available to the overall group of agents, through the local cooperation between each agent and its neighbors. As a consequence, each agent is capable of generating the desired steady-state distributed static control input by only exchanging information with its neighbors, without the need for additional dynamics anywhere in the network
Hybrid output regulation for nonlinear systems: Steady-state vs receding horizon formulation
No full textThe hybrid output regulation problem in the presence of periodic jumps is approached in
this paper for a class of nonlinear hybrid systems satisfying rather mild assumptions. We
provide sufficient conditions that characterize steady-state trajectories achieving output
regulation that are defined, mimicking the linear case, in terms of two equations: the first
one describes the solution of a flow-only output regulation problem, while the second is
associated to an auxiliary output regulation problem concerning the monodromy equivalent
system of the flow zero-dynamics. Such conditions are then revisited and a receding-horizon,
steady-state-less, solution to the (hybrid) output regulation problem is suggested, based on
the solution of a sequence of two-point boundary value problems
Constructive design of output feedback weakened anti-windup compensators for linear systems with additive/multiplicative perturbations
No full textA two-step algorithm for the synthesis of output feedback weakened anti-windup compensators is proposed for the case of additively perturbed systems. The first step determines a state feedback stabilizer guaranteeing a finite gain on a suitable nonlinear "mismatch" system. In the second step, a loop-shaping approach is adopted to design a linear filter which ensures overall robust stability, meanwhile minimizing the amount of anti-windup performance sacrificed. Both steps can be efficiently implemented using standard LMI software. © 2005 IEEE
Output regulation problems in hybrid systems
No full textThis entry discusses some of the salient features of the output regulation problem for hybrid systems, especially in connection with the steady-state characterization. In order to better highlight such peculiarities, the discussion is mostly focused on the simplest class of linear time-invariant systems exhibiting such behaviors. In comparison with the usual regulation theory, the role played by the zero dynamics and by the presence of more inputs than outputs is particularly striking
Modal consensus, synchronization and formation control with distributed endogenous internal models
No full textConsidering a group of heterogeneous agents communicating over a network, this paper introduces the innovative concept of Distributed Endogenous Internal Model as the key tool for a novel approach to formation control, synchronization and (modal) consensus. The novel strategy yields a dramatic reduction in terms of required communications and computations: in fact, while the usual approach to the mentioned problems entails that each agent is endowed with an internal model of the dynamics specifying the desired collective motion, in the novel approach such dynamics is distributed over the network among the agents, and it is realized in an endogenous fashion, namely by a suitable interconnection among parts of the dynamics already possessed by the agents, through the local cooperation between each agent and its neighbors. To address the cases when the purely endogenous solution is not viable, the related problem of how to minimally augment the dynamics of the overall network of agents in such cases is also studied
Frequency-domain analysis of linear systems with periodic jumps: Definition of hybrid transfer function, pole and zero
Full text linkA frequency-domain analysis is carried out for a class of linear systems in the presence of periodic time-driven jumps. The result is achieved by introducing the notion of transfer function in this context, and by relying on a suitably defined transform for hybrid arcs, whose properties are comprehensively discussed. It is firstly shown that knowledge of the transfer function permits the computation in closed-form of the complete (state and output) response of the hybrid plant, which may be otherwise intractable from the computational point of view. Moreover, the hybrid transfer function resulting from series interconnection of two plants is derived and exploited to introduce and discuss, in the single-input single-output case, the concepts of zero and pole of the hybrid transfer function. Differently from the classical purely continuous or discrete time cases, only a subset of the latter is related to the stability properties of the hybrid system
Data-Driven Dynamic Control Allocation for Uncertain Redundant Plants
No full textThis paper addresses the problem of achieving high-performance dynamic control allocation for uncertain plants by exploiting a data-driven design of the annihilator for the underlying plant. Previous work revealed that an output invisible control allocator can be decomposed as the cascade interconnection of a steady-state optimizer and an annihilator, where the latter unit modulates the allocator outputs in such a way to render such signals undetectable from the plant output. Clearly, the critical role and challenging requirements imposed on the annihilator make it the source of the fragility of control allocation schemes in the presence of uncertainty; nonetheless this critical aspect can be (almost) completely circumvented by tuning the annihilator to the actual plant parameters, namely by envisioning a data-driven control allocation scheme. Relations are also highlighted between the present results and the concepts of moments and orthogonal moments of a plant at frequencies of interest, whose use and estimation have recently been the subject of increasing interest
On the notion of transfer function for linear hybrid systems with periodic jumps
No full textIn this paper, we introduce the notion of transfer function for linear hybrid systems in the presence of time-driven periodic jumps. Such concept is employed to extend frequency-domain analysis tools - well-known and extensively used in the context of purely continuous or discrete time systems - to a class of hybrid systems. In particular, knowledge of the transfer function permits firstly the computation in closed-form of the complete forced (state or output) response of the hybrid plant. Moreover, the hybrid transfer function allows for the frequency-domain definition of the notion of 0-th moment of the underlying system, which is instrumental, e.g. for the solution to model reduction or system identification problems. It is shown, in addition, that the notion of moment based on the hybrid transfer function possesses an interesting time-domain counterpart, hence extending the results obtained for purely continuous-time systems. The paper is concluded by numerical simulations to further substantiate the theoretical claims
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