@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 = {<p>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.</p>
},
	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 {20,
	title = {Specific growth rate estimation in (fed-)batch bioreactors using second-order sliding observers},
	journal = {Journal of Process Control},
	volume = {21},
	year = {2011},
	pages = {1049 - 1055},
	abstract = {<p>This paper addresses the estimation of specific growth rate of microorganisms in bioreactors using sliding observers. In particular, a second-order sliding observer based on biomass concentration measurement is proposed. Differing from other proposals that only guarantee bounded errors, the proposed observer provides a smooth estimate that converges in finite time to the time-varying parameter. Stability is proved using a Lyapunov approach. The observer exhibits also robustness to process uncertainties since no model of the reaction is used for its design. In addition, the off-surface coordinate of the sliding observer is useful to determine the convergence time as well as to identify sensor faults and unexpected behaviors. Because of the structure of the output error injection, chattering phenomena of conventional sliding mode algorithms are substantially reduced. The features of the proposed observer are assessed by numerical and experimental data.</p>
},
	keywords = {Bioreactors},
	issn = {0959-1524},
	doi = {10.1016/j.jprocont.2011.05.008},
	url = {http://www.sciencedirect.com/science/article/pii/S0959152411000989},
	author = {De Battista, Hern{\'a}n and Pic{\'o}, Jes{\'u}s and Garelli, Fabricio and Vignoni, Alejandro}
}
