694 research outputs found

    Energy Shaping Control of an Inverted Flexible Pendulum Fixed to a Cart

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    Control of compliant mechanical systems is increasingly being researched for several applications including flexible link robots and ultra-precision positioning systems. The control problem in these systems is challenging, especially with gravity coupling and large deformations, because of inherent underactuation and the combination of lumped and distributed parameters of a nonlinear system. In this paper we consider an ultra-flexible inverted pendulum on a cart and propose a new nonlinear energy shaping controller to keep the pendulum at the upward position with the cart stopped at a desired location. The design is based on a model, obtained via the constrained Lagrange formulation, which previously has been validated experimentally. The controller design consists of a partial feedback linearization step followed by a standard PID controller acting on two passive outputs. Boundedness of all signals and (local) asymptotic stability of the desired equilibrium is theoretically established. Simulations and experimental evidence assess the performance of the proposed controller.Comment: 11 pages, 7 figures, extended version of the NOLCOS 2016 pape

    Passivity-Based Control

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    Stabilization of physical systems by shaping their energy function is a well-established technique whose roots date back to the work of Lagrange and Legendre. Potential energy shaping for fully actuated mechanical systems was first introduced in Takegaki and Arimoto (Trans ASME J Dyn Syst Meas Control 12:119--125, 1981) more than 30 years ago. In Ortega and Spong (Automatica 25(6):877--888, 1989) it was proved that passivity was the key property underlying the stabilization mechanism of these designs, and the, now widely popular, term of passivity-based control was coined. In this chapter we summarize the basic principles and some of the main developments of this controller design technique

    On Linearity, Phasors and Steady-State Response of Electrical Circuits

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    This note addresses the widespread and often unquestioned assumption that a linear circuit supplied by a sinusoidal input (voltage or current) always results in a sinusoidal output (current or voltage). Likewise, it is generally assumed that only nonlinear circuits can generate harmonic distortion. Based on the linearity assumption, the analysis of power systems properties is usually carried out using Fourier analysis and phasors. Such analyses typically neglect the transients and initial conditions. Two elementary examples are exploited to show that linearity alone is not sufficient to guarantee a sinusoidal steady- state response. It is necessary to invoke some additional assumptions. However, these assumptions contradict the underlying philosophy of phasors or are difficult to accomplish physics-wise

    Nous materials procedents de la Cova Santa de la Font de la Figuera

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    Estudi de materials cer脿mics de l'Horitz贸 Camapniforme de Transici贸 i de l'Edat del Bronze

    La Cova dels Diablets (Alcal脿 de Xivert, Castell贸). Prehist貌ria a la Serra d鈥 Irta

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    El llibre presenta les excavacions i tots els materials arqueol貌gics coneguts de la Cova dels Diablets a Alcal脿 de Xivert, una cavitat amb una seq眉猫ncia d'ocupaci贸 humana que s'inicia fa m茅s de 10.000 anys i finalitza al tercer mil鈥enni abans de l'era, documentant-s鈥檋i tamb茅 visites o usos posteriors en 猫poca hist貌rica. Amb la participaci贸 de diversos especialistes que analitzen cadascun dels aspectes de les ocupacions prehist貌riques, es presta especial atenci贸 a un vas cer脿mic decorat amb impressions i incisions del neol铆tic antic, especialment interessant dins del registre material de la cova

    New ceramic fragments from La Cova de la Sarsa (Bocairent, Valencia) belonging to the Ponsell Collection of the Alcoi Municipal Archaeological Museum

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    Presentem un petit lot de cer脿miques seleccionades que van ser recuperades en les excavacions realitzades per Fernando Ponsell a la Cova de la Sarsa (Bocairent, Val猫ncia), tornades fa poc al Museu Arqueol貌gic Municipal d鈥橝lcoi despr茅s de ser estudiades per M. D. Asquerino. Es tracta d鈥檜n conjunt t铆pic del Neol铆tic Antic Cardial. Finalment, assenyalem de forma breu algunes de les problem脿tiques en qu猫 actualment queda enquadrada la cova en el context del Neol铆tic antic local. Paraules clau: Cer脿mica, Cova de la Sarsa, Neol铆tic Antic, Fernando Ponsell.In this paper, the study of a small ceramics collection from Cova de la Sarsa (Bocairent, fieldwork campaign carried out by Fernando Ponsell, studied first by M.D. Asquerino, The lot in question is a typical assemblage from the Cardial ancient Neolithic. Furthermore, involving the local ancient Neolithic are specified. Key words: ceramics, Cova de la Sarsa, ancient Neolithic, Fernando Ponsell.Presentamos un peque帽o lote de cer谩micas seleccionadas que fueron recuperadas en las excavaciones realizadas por Fernando Ponsell en la Cova de la Sarsa (Bocairent, Valencia), recientemente devuelto al Museu Arqueol貌gic Municipal d鈥橝lcoi tras ser estudiado por M. D. Asquerino. Se trata de un conjunto t铆pico del Neol铆tico Antiguo Cardial. Finalmente, se帽alamos de forma breve algunas de las problem谩ticas en las que actualmente queda encuadrada la cueva en el contexto del Neol铆tico antiguo local. Palabras clave: Cer谩mica, Cova de la Sarsa, Neol铆tico Antiguo, Fernando Ponsell

    Model Reduction of Linear Port-Hamiltonian Systems: A Structure Preserving Approach

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    Extended balancing of continuous LTI systems:A structure-preserving approach

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    In this paper, we treat extended balancing for continuous-time linear time-invariant systems. We take a dissipativity perspective, thus resulting in a characterization in terms of linear matrix inequalities. This perspective is useful for determining a priori error bounds. In addition, we address the problem of structure-preserving model reduction of the subclass of port-Hamiltonian systems. We establish sufficient conditions to ensure that the reduced-order model preserves a port-Hamiltonian structure. Moreover, we show that the use of extended Gramians can be exploited to get a small error bound and, possibly, to preserve a physical interpretation for the reduced-order model. We illustrate the results with a large-scale mechanical system example. Furthermore, we show how to interpret a reduced-order model of an electrical circuit again as a lower-dimensional electrical circuit