Fernando Castaños

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—The dynamics of many physical processes can be suitably described by Port-Hamiltonian (PH) models, where the importance of the energy function, the interconnection pattern and the dissipation of the system is underscored. To regulate the behavior of PH systems it is natural to adopt a Passivity-Based Control (PBC) perspective, where the control objectives(More)
—We consider the problem of designing an integral sliding mode controller to reduce the disturbance terms that act on nonlinear systems with state-dependent drift and input matrix. The general case of both, matched and unmatched disturbances affecting the system is addressed. It is proved that the definition of a suitable sliding manifold and the generation(More)
—The robustness properties of integral sliding-mode controllers are studied. This note shows how to select the projection matrix in such a way that the euclidean norm of the resulting perturbation is minimal. It is also shown that when the minimum is attained, the resulting perturbation is not amplified. This selection is particularly useful if integral(More)
It is well known that if the linear time invariant system ˙ x = Ax + Bu, y = Cx is passive the associated incremental system ˙ ˜ x = A˜x + B˜u, ˜ y = C˜x, with˜(·) = (·) − (·) ⋆ , u ⋆ , y ⋆ the constant input and output associated to an equilibrium state x ⋆ , is also passive. In this paper, we identify a class of nonlinear passive systems of the form ˙ x =(More)
Passivity-based controllers (PBCs) achieve stabilization of nonlinear systems, rendering the closed-loop passive with a desired energy (storage) function. A natural question is, under which conditions is it possible to make this function equal to the difference between the plant and controller energies—when the controller is said to be energy-balancing. In(More)
— We present an adaptive sliding-mode extremum seeker that minimizes an unknown function that is subject to an unknown static constraint. The same algorithm can be applied when the static constraint is replaced by a dynamic one, provided that the dynamics possess strong stability properties. The application and feasibility study is focused on hydrogen(More)
—This work presents a nonsmooth adaptive extremum seeker that minimizes the hydrogen consumption in a fuel cell system. The extremum seeker operates by estimating the gradient of the objective function but, unlike other seekers, it does not require a dither signal to produce such estimate. The absence of a dither signal simplifies the choice of parameter(More)
— We propose an integral sliding surface for linear time-invariant implicit descriptions (descriptor systems). We show that, under reasonable assumptions (regularity, stabiliz-ability and a corresponding matching condition), it is possible to design a controller that drives the descriptor variables to zero, even in the presence of disturbances. Higher-order(More)
In this paper we identify graph-theoretic conditions which allow us to write a nonlinear RLC circuit as port-Hamiltonian with constant input matrices. We show that under additional monotonicity conditions on the network's components, the circuit enjoys the property of relative passivity, an extended notion of classical passivity. The property of relative(More)