@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 {88, title = {Lyapunov-Designed Super-Twisting Sliding Mode Control for Wind Energy Conversion Optimization}, journal = {Industrial Electronics, IEEE Transactions on}, volume = {60}, year = {2013}, month = {Feb}, pages = {538-545}, abstract = {

This work explores an adaptive second-order sliding mode control strategy to maximize the energy production of a wind energy conversion system (WECS) simultaneously reducing the mechanical stress on the shaft. Such strategy successfully deals with the random nature of wind speed, the intrinsic nonlinear behavior of the WECS, and the presence of model uncertainties and external perturbations acting on the system. The synthesized adaptive controller is designed from a modified version of the super-twisting (ST) algorithm with variable gains. The suitability of the proposed strategy is proved by extensive computer-aided simulations employing a comprehensive model of the system emulating realistic conditions of operation, i.e., considering variations in the parameters and including external disturbances. Additionally, a second controller based on the traditional ST algorithm is also designed and simulated. Results are presented and discussed in order to establish a comparison framework.

}, keywords = {adaptive control, adaptive second-order control strategy, Algorithm design and analysis, CAD, Computational modeling, control system synthesis, Control systems, direct energy conversion, extensive computer-aided simulations, external disturbances, external perturbations, Generators, intrinsic nonlinear behavior, Lyapunov methods, Lyapunov-designed super-twisting sliding mode control, mechanical stress reduction, model uncertainties, Sliding mode control, ST algorithm, suitability strategy, super-twisting (ST), system emulating realistic conditions, Torque, variable gains, variable structure systems, WECS, wind energy conversion optimization, wind power, Wind power generation, Wind speed, wind turbines}, issn = {0278-0046}, doi = {10.1109/TIE.2012.2188256}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6153362}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando and Fridman, Leonid M.} } @conference {91, title = {Variable gains super-twisting control for wind energy conversion optimization}, booktitle = {Variable Structure Systems (VSS), 2010 11th International Workshop on}, year = {2010}, month = {June}, abstract = {

An adaptive second order sliding mode control strategy is explored in this work, to maximize the energy extracted from the wind in a wind energy conversion system (WECS). It is required to such strategy to deal with the nonlinear nature of the WECS, the randomness of the wind speed, model uncertainties and external disturbances, and also with the need to reduce mechanical loads. The special features of this adaptive technique together with the robustness, relative simplicity and other desirable inherent characteristics of the super-twisting algorithm make the proposed controller an attractive solution. The suitability of the proposed strategy is proved by extensive computer aided simulations employing a comprehensive model of the system.

}, keywords = {adaptive control, adaptive second order sliding mode control, Computational modeling, computer aided simulation, Computer Simulation, control system synthesis, Gain, Lyapunov based controller design, Lyapunov methods, nonlinear systems, optimisation, Programmable control, Robust control, Sliding mode control, Uncertainty, variable gain super twisting control, variable structure systems, Wind energy, wind energy conversion optimization, wind power, Wind speed}, doi = {10.1109/VSS.2010.5544713}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5544713}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando and D{\textquoteright}ávila, A.} }