1,721,138 research outputs found
Velocity observers for non-linear mechanical systems subject to non-smooth impacts
No full textThis paper is concerned with the estimation of the velocity variables (when the position variables are the measured outputs) for non-linear mechanical systems subject to non-smooth impacts, both elastic and inelastic (i.e., with coefficient of restitution e â\u88\u88 = 1 and e(0,1), respectively). A reduced-order observer is proposed, which guarantees that the corresponding error system, despite the possible presence of an infinite sequence of non-smooth impacts, is locally exponentially stable. An estimate of the basin of attraction is also given. © 2002 Elsevier Science Ltd. All rights reserved
Velocity observers for linear mechanical systems subject to single non-smooth impacts
No full textIn this paper, we consider the problem of the velocity estimation from position measurement for linear mechanical systems (with multiple degrees of freedom) subject to single non-smooth impacts, both elastic and inelastic (i.e., with coefficient of restitution e = 1 and e â\u88\u88 (0, 1), respectively). Through a simple example, it is shown that a classical Luenberger observer is not able to reproduce instantaneously the jumps in the mass velocities, since it recovers the error induced by such jumps only asymptotically: an infinite sequence of impacts can prevent the estimation error to asymptotically go to zero. A new observer structure is proposed for linear mechanical systems subject to single unilateral constraints, that guarantees that the corresponding error dynamics are exponentially stable, also in presence of an infinite sequence of non-smooth impacts. The observer that we propose switches at the impact times, that can be recognized by position measurements only. To validate the proposed observer, both simulation and experimental tests have been carried out and are briefly reported, pointing out the drawbacks and advantages of the observer. © 2001 Elsevier Science B.V. All rights reserved
Input/output decoupling problems for high speed trains
No full textDifferent input/output decoupling problems for a nonlinear model of high speed trains are studied. As it is natural in applications, the input/output decoupling is only one of the requirements, which is to be obtained together with asymptotic stability and asymptotic set point output regulation, in the presence of constant disturbances
Dynamic position feedback stabilisation of multidegrees-of-freedom linear mechanical systems subject to nonsmooth impacts
No full textThe goal of the paper is to extend some previous results concerned with state feedback stabilisation of mechanical systems subject to nonsmooth impacts, to the case when only position measurements are available for feedback. Fully actuated n-degrees-of-freedom mechanical systems are considered (whereas earlier studies considered only one-degree-of-freedom systems) whose dynamics would be linear in the absence of the inequality constraint delimiting the admissible region. For such systems, a class of compensators that ensures exponential and BIBS stabilisation (without using velocity measurements, which were requested in earlier studies) is proposed and their efficacy is proven by means of Lyapunov techniques. Simulations and experimental results are included to show the effectiveness of the theory presented
Dead-beat control laws for impacting systems in presence of uncertainties
No full textThe issues for impacting systems in the presence of uncertainties are addressed. In particular, the control laws for both nominal and perturbed systems are demonstrated
State estimation for the Newton's cradle: A mechanism that is unobservable in absence of impacts
No full textAbstractWe consider a simplified Newton's cradle, which would be unobservable if the non-smooth impacts between the spheres were ignored. Nevertheless, under the assumption that there is an infinite sequence of nonsmooth impacts, it is possible to design an observer that is able to asymptotically estimate all the nonmeasurable state variables, including those that would be unobservable in absence of impacts
Exponential and BIBS stabilisation of one degree of freedom mechanical systems subject to single non-smooth impacts
No full textThe problem of exponential and BIBS stabilisation of one degree of freedom mechanical systems subject to single non-smooth impacts, both elastic and inelastic (i.e. with coefficient of restitution e = 1 and e â\u88\u88 [0, 1), respectively), is considered, under the assumption that the state variables of the system are measurable. To validate the proposed control law, both simulation and experimental tests have been carried out and are briefly reported
Asymptotic tracking of periodic trajectories for a simple mechanical system subject to nonsmooth impacts
No full textAn infinitely rigid mass is considered, which moves on a plane under the action of proper forces, within a closed region delimited by an infinitely massive and rigid circular barrier. A suitably amended tracking problem for a class of periodic trajectories, involving an infinite number of nonsmooth impacts between the mass and the barrier, is formally stated and solved
Modelling and control of an impacting flexible circular ring
No full textIn this paper, the problem of damping the impact induced vibrations of a circular ring is studied. Finite dimensional models of the structure are derived, based on the use of the eigenfunctions of the vibrating structure. The impacts are modelled by using the Valentine variables method in order to take into account the presence of the inequality constraint. The controllability of the finite-dimensional approximate models of the systems by means of the available control inputs is studied. Finally, the performance of a derivative control law is investigated
Reduced-order observers for the velocity estimation of non-linear mechanical systems subject to non-smooth impacts
No full textThe problem of the velocity estimation from position measurement for multi-degrees-of-freedom non-linear mechanical systems subject to non-smooth impacts, is considered. A reduced-order observer is proposed, which guarantees that the corresponding error dynamics are locally exponentially stable, also in presence of an infinite sequence of non-smooth impacts
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