@article {243, title = {Output Feedback Linearization of Turbidostats After Time Scaling}, journal = {IEEE Transactions on Control Systems Technology}, volume = {27}, year = {2019}, pages = {1668-1676}, abstract = {

Turbidostats are a class of bioreactors gaining interest due to the recent availability of microscale and small-scale devices for characterization and scalingup of the biotechnological systems relevant in the biotech and pharma industries. The goal is to keep cell density constant in continuous operation. Thus, the control law, i.e., the substrate feeding strategy, must guarantee global or semiglobal convergence to an equilibrium point. However, their control is difficult due to the uncertain, time varying, and nonlinear nature of the processes involved. In this brief, we propose an adaptive control law that globally stabilizes the desired biomass setpoint. Furthermore, in a certain region of the state space, the controller linearizes the dynamic behavior after some time scaling. By this way, the orbits of the closed-loop system are imposed by the designer. The intrinsic integral action of the gain adaptation rejects the parameter uncertainties. Moreover, the controller implementation only assumes the biomass concentration to be measured. Both the simulated and experimental results show the performance of the controller.

}, keywords = {adaptive control, Asymptotic stability, Biological system modeling, Biomass, Bioreactors, Convergence, Nonlinear control systems, output feedback, Substrates}, issn = {1063-6536}, doi = {10.1109/TCST.2018.2834882}, author = {De Battista, Hern{\'a}n and Pic{\'o}-Marco, Enric and Santos-Navarro, Fernando N. and Pic{\'o}, Jes{\'u}s.} } @article {115, title = {2-sliding active and reactive power control of a wind energy conversion system}, journal = {Control Theory Applications, IET}, volume = {4}, year = {2010}, month = {November}, pages = {2479-2490}, abstract = {

This study presents the control of a variable-speed wind energy conversion system based on a brushless doubly fed reluctance machine. The control objectives are the tracking of the maximum power conversion point and the regulation of the reactive power injected by the generation system into the grid. The control design is approached using multi-input second-order sliding techniques which are specially appropriate to deal with non-linear system models in the presence of disturbances and model inaccuracies. The controller synthesised through this theoretical framework presents very good robustness features, a finite reaching time and a chattering-free behaviour. The performance of the closed-loop system is assessed through representative computer simulations.

}, keywords = {2-sliding active power control, 2-sliding reactive power control, brushless doubly fed reluctance machine, brushless machines, chattering-free behaviour, closed loop systems, closed-loop system, control design, control system synthesis, controller synthesis, generation system, grid, maximum power conversion point tracking, multiinput second-order sliding technique, Nonlinear control systems, nonlinear system model, Power conversion, power generation control, reactive power control, reactive power regulation, reluctance machines, representative computer simulation, variable structure systems, variable-speed wind energy conversion system, wind power}, issn = {1751-8644}, doi = {10.1049/iet-cta.2009.0437}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5645800}, author = {Valenciaga, Fernando and Evangelista, Carolina A.} } @conference {104, title = {A Geometric Approach for the Design of MIMO Sliding Controllers. Application to a Wind Driven Double Output Induction Generator}, booktitle = {Variable Structure Systems, 2006. VSS{\textquoteright}06. International Workshop on}, year = {2006}, month = {June}, abstract = {

This paper presents a systematic methodology to design controllers for a general class of nonlinear MIMO systems affine in the control in the presence of bounded uncertainties and disturbances. The proposed design method is developed through a theoretical framework based on the combination of a geometric approach and sliding mode techniques. The resulting robust control law guarantees finite time convergence, while chattering reduction is attained by utilising the minimum discontinuous action required to ensure disturbance rejection. The proposed methodology is applied to the control of a grid connected wind energy generation system based on a double output induction generator

}, keywords = {asynchronous generators, chattering reduction, control system synthesis, Control systems, controller design, Convergence, Design methodology, finite time convergence, geometric approach, grid connected wind energy generation system, Induction generators, MIMO, MIMO sliding mode controllers, MIMO systems, Nonlinear control systems, nonlinear MIMO systems, power generation control, Robust control, Sliding mode control, Uncertainty, variable structure systems, wind driven double output induction generator, Wind energy generation, wind power}, doi = {10.1109/VSS.2006.1644503}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1644503}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Spurgeon, Sarah} } @article {65, title = {Comments on "variable-structure PID control to prevent integrator windup"}, journal = {Industrial Electronics, IEEE Transactions on}, volume = {51}, year = {2004}, month = {June}, pages = {736-738}, abstract = {

In the paper by Hodel and Hall, the authors introduce a variable-structure proportional-integral-derivative controller with antiwindup features and compare it with other simple antiwindup methods. It is pointed out here that the conclusions reached from the comparative example are incorrect as the performance of the controllers is not appropriately compared.

}, keywords = {Antiwindup, antiwindup features, Control nonlinearities, Control systems, controllers, Degradation, Furnaces, integrator windup protection, Internet, linear systems, Nonlinear control systems, performance limitations, PID control, Proportional control, proportional-integral-derivative controller, three-term control, variable structure systems, variable-structure systems, Windup}, issn = {0278-0046}, doi = {10.1109/TIE.2004.825205}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1302353}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n} }