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Performance Assessment of Constrained controllers

IFAC Proceedings Volumes 2004年第1期37卷 185-190页

作者： Lilong Huang Christos Georgakis Chemical Process Modeling and Control Research Center and Department of Chemical Engineering Lehigh University Bethlehem Pennsylvania 18015 Department of Chemical Engineering Chemistry and Material Science 728 Rogers Hall Polytechnic University Six Metrotech Center Brooklyn NY 11201 USA Phone: (718) 260- 3579 Fax: (718) 260-3125

The paper presents a new deterministic framework for assessing constrained control loop performance. The proposed dynamic performance index is based on the dynamic operating work of Uztürk and Georgakis (2002). It focuses on the time related characteristics of controllers' response to set-point changes or steptype disturbances. It explicitly takes into account the existence of constraints on manipulated variables. These constraints include minimum and maximum values as well as an upper limit on the rate of change of the input variables.

关键词： Constrained controller Performance Assessment Time Optimal control Minimum Settling Time Deterministic Disturbances

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Real-time estimation and control of particle size in semi-batch emulsion polymerization

Real-time estimation and control of particle size in semi-ba...

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American control Conference (ACC)

作者： V. Liotta C. Georgakis M.S. El-Aasser Air Products and Chemicals Inc. Allentown PA USA Chemical Process Modeling and Control Research Center and Emulsion Polymers Institute Lehigh University Bethlehem PA USA

The control of the relative particle growth of a bidisperse emulsion polymerization is investigated in an automated reactor control facility capable of online density and online particle size measurements. Final diameter ratio values are controlled by manipulating the monomer feed rate to the reactor using a control scheme comprised of a parameter adaptive Kalman filter with steady state gains and a nonlinear model predictive controller. One of the main features of the implemented controller is the connection of the prediction horizon to the criterion that the overall conversion equal 90% at the end of the batch. Feedback is incorporated into the algorithm at each sampling time by starting the model prediction calculation at the current estimated values of the model states. The controller performs well to meet a challenging diameter ratio set point at the end of the batch. The robustness of the controller to reject an induced initial initiator concentration disturbance is demonstrated.

关键词： Size control Automatic control Predictive models Inductors Polymers Size measurement Feeds Programmable control Adaptive control Steady-state

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control of a Heat-Integrated Complex Distillation Configuration

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IFAC Proceedings Volumes 1989年第8期22卷 69-76页

作者： S.S. Ding W.L. Luyben Eastman Kodak Company 2400 Mt. Read Boulevard Rochester New York 14652 USA Process Modeling and Control Center Department of Chemical Engineering Lehigh University 111 Research Drive Bethlehem PA 18015 USA

Several steadystate design studies of distillation systems that combine complex configurations (prefractionators and sidestream columns) and heat integration have appeared in the literature and have shown the potential for large reductions (50%) in energy consumption compared to conventional designs. However, the dynamics and control aspects of these highly interactive and multivariable systems have been virtually unexplored. This paper presents the results of computer simulation studies of the dynamic controllability of a complex heat-integrated distillation system for the ternary mixture of benzene, toluene and m-xylene. Both low and high-purity separations were explored. For the low-purity (95% product purities) separation, the complex heat-integrated system was found to be controllable and gave dynamic responses that were comparable to the simple conventional system. A diagonal multi-loop SISO controller structure was successful in controlling this 3x3 multivariable process. controlled variables were the three product purities. Manipulated variables were the flow rates of reflux, sidestream and reboiler steam. For the high-purity (99.9%) separation, the complex heat-integrated system was found to be controllable but could only handle small (<10%) feed composition disturbances and was dynamically worse than the conventional system. The control structure used in the low-purity separation did not work in the high-purity separation because of severe nonlinearity. To decrease the nonlinearity, a control structure was developed that maintained the two impurities in the toluene sidestream product instead of the toluene purity. The additional manipulated variable needed in this modified process (now a 4x4 multivariable process) was achieved by changing the sidestream drawoff-tray location.

关键词： Heat integration distillation control multivariable processes

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An optimal control problem in closed-loop neuroprostheses

An optimal control problem in closed-loop neuroprostheses

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IEEE Conference on Decision and control

作者： Gautam Kumar Vikram Aggarwal Nitish V. Thakor Marc H. Schieber Mayuresh V. Kothare Chemical Process Modeling and Control Center Department of Chemical Engineering Lehigh University Bethlehem PA USA Department of Biomedical Engineering Johns Hopkins University Baltimore MD USA Department of Neurobiology and Anatomy University of Rochester Medical Center Rochester NY USA

ISBN: (纸本)9781612848006;9781612848013

A control-theoretic study of complex systems such as closed-loop neural prostheses exhibits several challenges, from the design of an optimal feedback control problem to its solution. In this paper we study one such system, a closed-loop voluntary movement of a prosthetic finger using electrophysio-logical activities of a single cortical motor neuron. We develop an optimal feedback control problem in the nonlinear receding horizon based terminal set constraint framework. We analyze the feasibility and stability of the control problem. Further, we solve the control problem numerically by implementing a local optimum based nonconvex nonlinear programming algorithm. Finally, we study effects of visual and proprioceptive feedback pathways on the closed-loop system. Our results elucidate the importance of multiple feedback paths in designing a closed-loop neural prosthetic system.

关键词： Prosthetics Neurons Visualization Noise Optimization Torque Indexes

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The Effect of controllers in State Estimation Schemes

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IFAC Proceedings Volumes 1998年第11期31卷 577-582页

作者： Guillermo E. Eliçabe Christos Georgakis Departamento de Ingeniería Química/INTEMA Facultad de Ingeniería Universidad Nacional de Mar del Plata (7600) Mar del Plata Argentina Chemical Process Modeling and Control Research Center Lehigh University Iacocca Hall #111 Bethlehem PA 18015 USA

It is common practice in state estimation of chemical systems to include augmented states modeled as random constant or random walk processes. When in these systems, process controllers with integral term are present, undesirable interaction effects may occur between the augmented states and the controllers. It was noted in practice that if no attention is paid to this interaction the resulting estimator may diverge. In this work the interaction between controller and augmented states is analyzed. Using linear systems theory, it is shown that the unwanted interaction and final divergence are caused by lack of observability at steady state and consequently a test to check observability at steady state is developed. In many cases the test can be performed by simple inspection. When this is not the case, results can be obtained after a few manipulations. A series of examples are given where the concept of observability at steady state is applied to help detecting and preventing the negative interaction between controllers and augmented states. Finally, a discussion is presented comparing the results of the standard observability test, applied to a real problem, with those obtained with the test developed here and with the behavior of a real estimator for the same problem. It is concluded that the standard observability test is not able to discriminate between different estimator designs and consequently to produce practical results as those obtained with the alternative test, i.e. the detection of unfeasible estimator designs.

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Optimal parameter estimation of the Izhikevich single neuron model using experimental inter-spike interval (ISI) data

Optimal parameter estimation of the Izhikevich single neuron...

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American control Conference

作者： Gautam Kumar Vikram Aggarwal Nitish V. Thakor Marc H. Schieber Mayuresh V. Kothare Chemical Process Modeling and Control Center Department of Chemical Engineering Lehigh University Bethlehem PA 18015 U.S.A. Department of Biomedical Engineering Johns Hopkins University Baltimore MD 21205 U.S.A. Department of Neurobiology and Anatomy University of Rochester Medical Center Rochester NY 14627 U.S.A.

ISBN: (纸本)9781424474264

We propose to use the Izhikevich single neuron model to represent a motor cortex neuron for studying a control-theoretic perspective of a neuroprosthetic system. The problem of estimating model parameters is addressed when the only available data from intracortical recordings of a neuron are the Inter-Spike Intervals (ISIs). Non-linear constrained and unconstrained optimization problems are formulated to estimate model parameters as well as synaptic inputs using ISIs data. The primal-dual interior-point method is implemented to solve the constrained optimization problem. Reasonable model parameters are estimated by solving these optimization problems which may serve as a template for studying and developing a model of ensemble cortical neurons for neuroprosthesis applications.

关键词： Neurons model parameters optimal parameter UNCONSTRAINED OPTIMISATION Parameter estimation available data jigs(templates)

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Computationally efficient scheduled model predictive control for constrained nonlinear systems with stability guarantees

Computationally efficient scheduled model predictive control...

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American control Conference (ACC)

作者： Zhaoyang Wan M.V. Kothare Department of Chemical Engineering Chemical Process Modeling and Control Research Center Lehigh Universit Bethlehem PA USA Department of Chemical Engineering Lehigh University Bethlehem PA U.S.A Lehigh University Bethlehem PA US Dept. of Chem. Eng. Lehigh Univ. Bethlehem PA USA

We present a computationally efficient scheduled formulation of model predictive control (MPC) for constrained nonlinear systems with large operating regions. We design a set of local predictive controllers with their explicit regions of stability covering the desired operating region, and implement them as a single scheduled MPC which switches between the set of local controllers and achieves nonlinear transitions with guaranteed stability. This algorithm is computationally efficient and provides a general framework for scheduled MPC design.

关键词： processor scheduling Computational modeling Predictive models Predictive control Nonlinear systems Robust stability Nonlinear control systems control systems Switches Robust control

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A Study of a Gun-Turret Assembly in an Armored Tank using Model Predictive control

A Study of a Gun-Turret Assembly in an Armored Tank using Mo...

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2009 American control Conference (ACC 2009)

作者： Gautam Kumar Pradeep Y. Tiwari Vincent Marcopoli Mayuresh V. Kothare Chemical Process Modeling and Control Center Department of Chemical Engineering Lehigh University Bethlehem PA 18015 U.S.A. Process Dynamics and Optimization group Bayer Technology Services Americas 8500 W Bay Rd Baytown TX 77523 U.S.A. General Dynamics Land Systems Sterling Hts. MI 48310 U.S.A.

ISBN: (纸本)9781424445233

Operation of the gun/turret system in a military tank is limited by several constraints some of which are posed by obstacles existing on the vehicle's own platform. These mechanical constraints acting as hard constraints can cause serious damage to the whole assembly if violated. A control strategy developed for such a system must avoid possible collision of the gun/turret system with these obstacles. We propose to use a MPC based control strategy, due to its inherent ability to handle constraints, for the deck clearance problem and evaluate its performance under operating conditions for a linear model of the tank. Matlab~R based MPCtoolbox is used to set up the MPC calculations for the gun/turret system. Simulations are performed to investigate and compare the performance of the controller under various deck constraint limits. It is shown that MPC is effective in addressing both the stabilization and deck clearance objectives.

关键词： Maximum Allowable Concentration control strategy Tanks belted distributed model predictive control nonlinear model predictive control Constraint Model predictive control Predictive control linear models Addressing assemblies Operating conditions vehicle controllers

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Guest Editorial

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Journal of process control 2000年第2-3期10卷 95-95页

作者： Christos Georgakis Lehigh University Chemical Process Modeling and Control Research Center Iacocca Hall 111 Research Drive Bethlehem PA 18015 USA

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Corrigendum to "8-Hydroxyquinoline based chitosan derived carbohydrate polymer as biodegradable and sustainable acid corrosion inhibitor for mild steel: Experimental and computational analyses" [Int. J. Biol. Macromol. 26 (1) (2020) 645-655]

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International journal of biological macromolecules 2023年 232卷 123744页

作者： M Rbaa M Fardioui Chandrabhan Verma Ashraf S Abousalem M Galai E E Ebenso T Guedira B Lakhrissi I Warad A Zarrouk Laboratory of Agro-Resources Polymers and Process Engineering Department of Chemistry Faculty of Science Ibn Tofail University PO Box 133 14000 Kenitra Morocco. Electronic address: mohamed.rbaa10@***. Laboratory of Materials Electrochemistry and Environment Ibn Tofail University Faculty of Sciences Kenitra Morocco. Center of Research Excellence in Corrosion Research Institute King Fahd University of Petroleum & Minerals Dhahran 31261 Saudi Arabia Department of Chemistry School of Chemical & Physical Sciences and Material Science Innovation & Modelling (MaSIM) Research Focus Area Faculty of Agriculture Science and Technology North-West University (Mafikeng Campus) Private Bag X2046Mmabatho 2735 South Africa. Chemistry Department Faculty of Sciences Mansoura University El-Mansoura 35516 Egypt Quality Control Laboratory Operations Department JOTUN Egypt. Laboratory of Materials Engineering and Environment: Application and Modeling Faculty of Sciences Ibn Tofail University PO Box 133 14000 Kénitra Morocco. Laboratory of Agro-Resources Polymers and Process Engineering Department of Chemistry Faculty of Science Ibn Tofail University PO Box 133 14000 Kenitra Morocco. Department of Chemistry and Earth Sciences PO Box 2713 Qatar University Doha Qatar. Laboratory of Materials Nanotechnology and Environment Mohammed V University Faculty of Sciences P.O. Box. 1014 Rabat Morocco. Electronic address: azarrouk@***.

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