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

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

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

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

Estudi de materials ceràmics de l'Horitzó Camapniforme de Transició i de l'Edat del Bronze

La Cova dels Diablets (Alcalà de Xivert, Castelló). Prehistòria a la Serra d’ Irta

El llibre presenta les excavacions i tots els materials arqueològics coneguts de la Cova dels Diablets a Alcalà de Xivert, una cavitat amb una seqüència d'ocupació humana que s'inicia fa més de 10.000 anys i finalitza al tercer mil•lenni abans de l'era, documentant-s’hi també visites o usos posteriors en època històrica. Amb la participació de diversos especialistes que analitzen cadascun dels aspectes de les ocupacions prehistòriques, es presta especial atenció a un vas ceràmic decorat amb impressions i incisions del neolític 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

Presentem un petit lot de ceràmiques seleccionades que van ser recuperades en les excavacions realitzades per Fernando Ponsell a la Cova de la Sarsa (Bocairent, València), tornades fa poc al Museu Arqueològic Municipal d’Alcoi després de ser estudiades per M. D. Asquerino. Es tracta d’un conjunt típic del Neolític Antic Cardial. Finalment, assenyalem de forma breu algunes de les problemàtiques en què actualment queda enquadrada la cova en el context del Neolític antic local. Paraules clau: Ceràmica, Cova de la Sarsa, Neolític 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 pequeño lote de cerámicas seleccionadas que fueron recuperadas en las excavaciones realizadas por Fernando Ponsell en la Cova de la Sarsa (Bocairent, Valencia), recientemente devuelto al Museu Arqueològic Municipal d’Alcoi tras ser estudiado por M. D. Asquerino. Se trata de un conjunto típico del Neolítico Antiguo Cardial. Finalmente, señalamos de forma breve algunas de las problemáticas en las que actualmente queda encuadrada la cueva en el contexto del Neolítico antiguo local. Palabras clave: Cerámica, Cova de la Sarsa, Neolítico Antiguo, Fernando Ponsell