Ramírez, Hector Miguel

This paper deals with the finite dimensional modelling and control of an electro-active polymer (EAP) actuated flexible structure. This model reproduces the basic mechanical properties of a class of one dimensional flexible endoscope. The flexible structure and the EAP actuator are both modelled as port-Hamiltonian systems. The EAP actuator is interconnected with the flexible structure in a power preserving manner such that the global system is again a PHS. Using the obtained model, two passivity based control strategies are applied to derive the controllers which achieve a desired equilibrium configuration with desired dynamic behaviour. An experimental benchmark composed of the Ionic Polymer Metal Composites patches glued to a flexible beam is used to validate the proposed model and control law.

Electrochemical processes have been developed for a wide range of applications such as, mineral refining, water purification, energy storage and generation. The development of models to describe these processes is very important for their analysis, optimization and operation. The framework of irreversible port-Hamiltonian systems has proven to be an important tool to analyze and integrate thermal models with models of different domains. This work discusses the modeling of non-isothermal electrochemical processes as irreversible port-Hamiltonian systems. An irreversible port-Hamiltonian model based on the internal energy function is derived for a simple but general example. The irreversible model is obtained from the molar and charge balance equations combined with the entropy balance equation. The resulting model can be interpreted as a thermodynamic system and aspects such as entropy production, thermodynamic driving forces and intensive/extensive variables are encoded in the representation. An electrochemical process with two simultaneous reactions is considered to illustrate the approach. The interconnection with a resistive load is also considered to illustrate the benefit of the port-based formulation of the model.

The observer design for 1D boundary controlled infinite-dimensional systems is addressed using the port-Hamiltonian approach. The observer is defined by the same partial differential equations as the original system and the boundary conditions depend on the available information from sensors and actuators. The convergence of the observers is proved to be asymptotically or exponentially under some conditions. The vibrating string and the Timoshenko beam are used to illustrate the observer convergence in different scenarios.

The control of a flexible beam using ionic polymer metal composites (IPMCs) is investigated in this paper. The mechanical flexible dynamics are modelled as a Timoshenko beam. The electric dynamics of the IPMCs are considered in the model. The port-Hamiltonian framework is used to propose an interconnected control model of the mechanical flexible beam and IPMC actuator. Furthermore, a passive and Hamiltonian structure-preserving linear quadratic Gaussian (LQG) controller is used to achieve the desired configuration of the system, and the asymptotic stability of the closed-loop system is shown using damping injection. An experimental setup is built using a flexible beam actuated by two IPMC patches to validate the proposed model and show the performance of the proposed control law.

—In this letter, we consider the exponential stabilization of a distributed parameter port-Hamiltonian system interconnected with an unstable finite-dimensional linear system at its free end and control input at the opposite one. The infinite-dimensional system can also have in-domain anti-damping. The control design passes through the definition of a finite-dimensional linear system that “embeds” the response of the distributed parameter model, and that can be stabilized by acting on the available control input. The conditions that link the exponential stability of the latter system with the exponential stability of the original one are obtained thanks to a Lyapunov analysis. Simulations are presented to show the pros and cons of the proposed synthesis methodology.

A comparative study of passivity based boundary control design for a class of infinite dimensional port-Hamiltonian system using two different model reduction approaches is presented. The first approach is based on a direct low order structure preserving discretization while the second approach arise from the structure preserving model reduction of a high order discretzed model. Two passivity-based control techniques, namely control by interconnection and damping injection, are used to change the equilibrium point and the convergence rate of the closed-loop system. An Euler-Bernoulli beam example is used to illustrate the findings by means of discussion and numerical simulations.

This paper investigates the observer design for the 1D boundary controlled port-Hamiltonian systems (BC-PHS) using the late lumping approach. Different observers are proposed for BC-PHS with different measured boundary variables. Based on the passivity propriety of the BC-PHS, sufficient conditions of the observer error convergence are provided for the different proposed observers. The wave equation is used to illustrate the effectiveness of the proposed observers with different boundary sensing.

This paper aims to propose a finite-dimensional observer-based state feedback controller to stabilize a class of boundary controlled system. To this end, we propose to use an early-lumping approach, where the infinite-dimensional port-Hamiltonian system is first discretized using a structure-preserving method. Then, we build a passive observed-based controller using a Linear Matrix Inequality (LMI) and finally, the controller is interconnected with the infinite-dimensional system in a passive way. Due to its passivity and Hamiltonian structure, this observer-based controller can stabilize not only the discretized lumped parameter system but also the original distributed parameter system. This approach avoids the intrinsic drawback of early lumping approach and spillover effects. Finally, the boundary controlled undamped wave equation is used to illustrate the effectiveness of the proposed controller.

This article studies robust output tracking and disturbance rejection for boundary-controlled infinite-dimensional Port– Hamiltonian systems including second-order models such as the Euler–Bernoulli beam equation. The control design is achieved using the internal model principle and the stability analysis using a Lyapunov approach. Contrary to existing works on the same topic, no assumption is made on the external well-posedness of the considered class of PDEs. The results are applied to robust tracking of a piezo actuated tube used in atomic force imaging.

In this paper, an irreversible port-Hamiltonian formulation for 1D compressible Newtonian fluids is presented. We separate the fluid dynamics into reversible and irreversible parts. Given the compressibility assumption, we define a state-dependent matrix that modulates the skew-symmetric operators that describe the irreversible part of the fluid dynamics. As a result, we obtain an energy-based formulation that reflects appropriately the first and second laws of Thermodynamics.