Lina M. Gómez

Limitaciones de la Controlabilidad de Estados en los Procesos por Lotes

This work shows the most important barriers found when controllability of batch processes is analyzed. The need of including irreversibility and initial state irrecoverability into that analysis is highlighted. Two study cases are analyzed. The conclusion is that such systems do not verify the controllability and therefore it is only possible to analyze the reachability of this kind of batch processes. Furthermore, it is shown through simulations that control action effect is limited and there is a strong dependency between initial conditions and batch evolution, which must be considered in then design of batch process controllers.

An approach to stability and controllability analysis in batch processes using set theory methods

A barely approached of the topics in the area of Batch Process (BP) Control is controllability and stability analysis. This is because the dynamic characteristic of BPs makes the traditional analysis of these properties harder. Characteristics like the transitory dynamics of the states and the irreversibility of the states (from the dynamic systems point of view) are serious obstacles for the use of classic tools to make an analysis of stability and controllability in BP, therefore, other tools should be used in order to come closer to a theoretical analysis on BP control. One approach is the use of some set theorys definitions. This paper uses the Controllable Trajectories Sets (CTS) to carry out a theoretical analysis on BP control.

Model based predictive strategy for dissolved oxygen control applied to a batch bioprocess

This paper proposes a novel Model Predictive Control strategy of dissolved oxygen (DO). The control design finds application on the Bt delta-endotoxins batch process production. This strategy improves the DO control by preventing the usual drawbacks that appear with a step level change in the DO reference profile. Simulations results are provided as well as comparison results against a well-known Lyapunov based controller and a classical PID controller.

Bacillus thuringiensis process design using state controllability index

Batch processes are inherently irreversible. In fact, design parameters and initial states can affect irreversibility and controllability of a batch process. Current design methodologies do not include controllability as a criterion for process specification. In this work, the case of Bacillus thuringiensis process is studied in batch operation, and its operational conditions are defined according to a phenomenological-based model. Regarding process design, a novel methodology is presented using set-theoretic methods and a controllability index to find the best design parameter and initial state values. Using this methodology the controllability index is doubled improving the dynamic behavior of the process.

Una Aproximación a la Cuantificación de la Controlabilidad de Estado

espanolEn este articulo se propone un indice numerico para cuantificar la controlabilidad de estado para sistemas no lineales suaves y continuos en el tiempo. Con base en la informacion contenida en los conjuntos alcanzable y controlable, se define el conjunto reversible en un tiempo t para un sistema dado. Se propone una medida del tamano y de la forma del conjunto reversible en un espacio n-dimensional, las cuales permiten cuantificar la controlabilidad de estado en una escala de cero a uno, y se definen procedimientos de calculo adecuados. Se calcula el indice de controlabilidad para tres casos de estudio verificando asi su correspondencia con la controlabilidad real. La inclusion del factor tiempo y las restricciones en las acciones de control para el analisis de controlabilidad de sistemas no lineales resulta ser una herramienta util para la implementacion de sistemas de control. EnglishIn this paper a numerical index for quantifying state controllability for continuous and smooth nonlinear systems is proposed. With information obtained from the reachable and controllable sets, a reversible set at time t for a given system is defined. Size and shape measurements of a reversible set in an n-dimensional space are proposed allowing state controllability on a scale from zero to one. Procedures to compute such indexes are detailed. State controllability index is computed for three study cases verifying its correspondence with real controllability. The inclusion of time and admissible input constraints for state controllability analysis of nonlinear systems showed to be a useful tool for real control system implementation.

Dynamic modeling of coffee beans dryer

Modeling of processes is becoming a powerful tool for understanding their dynamic behavior. In coffee drying process, the current models are based on empiric approximations and fluid dynamic studies. These last models are very computationally demanding for control and dynamic analysis purposes. The proposed model is an approximation that permits prediction, optimization and control systems design without losing rigorousness. Model is based on conservative principles and causal equations. Model validation is qualitative and this model can be used for analysis and design.

State controllabillity analysis and re-design for a wastewater treatment plant

In this paper a analysis of state controllability for the dynamical behavior of a wastewater treatment plant is presented. This plant is a large non-linear system subject to large disturbances. Based on a state controllability analysis a redesign for the plant is proposed. State controllability analysis is done by using set theory. This allows checking the controllability limits for the system. Indeed it allows including disturbance limits and constraints on control inputs. In this way, nominal design parameters determine the system controllability while other parameters would improve this system property. Finally, improvements in controllability issues for the system are presented.