The contribution presents the results of a collaborative R&D effort of two private companies and two national research institutions, joined at the European level. It was aimed to develop an enhanced on-line predictor of the strip thickness in the rolling gap. The issue dealt with is the absence of a reliable delay-free measurement of the outgoing strip thickness or the gap size, making the thickness control a challenging task. Although several satisfactory solutions have been used for decades, and modern control theory has been exploited as well, the pervasive competition in the field of metal strip processing emphasizes the need of a novel, more precious measuring method. The solution developed within the completed project is based on a parallel run of several adaptive Bayesian predictors whose outputs are continuously mixed to provide the best available rolling gap size prediction. The system was already tested in open loop in a real industrial environment for two reversing cold rolling mills processing steel and copper alloys strips, respectively.
{"title":"Bayesian model mixing for cold rolling mills: Test results","authors":"P. Ettler, Ivan Puchr, K. Dedecius","doi":"10.1109/PC.2013.6581437","DOIUrl":"https://doi.org/10.1109/PC.2013.6581437","url":null,"abstract":"The contribution presents the results of a collaborative R&D effort of two private companies and two national research institutions, joined at the European level. It was aimed to develop an enhanced on-line predictor of the strip thickness in the rolling gap. The issue dealt with is the absence of a reliable delay-free measurement of the outgoing strip thickness or the gap size, making the thickness control a challenging task. Although several satisfactory solutions have been used for decades, and modern control theory has been exploited as well, the pervasive competition in the field of metal strip processing emphasizes the need of a novel, more precious measuring method. The solution developed within the completed project is based on a parallel run of several adaptive Bayesian predictors whose outputs are continuously mixed to provide the best available rolling gap size prediction. The system was already tested in open loop in a real industrial environment for two reversing cold rolling mills processing steel and copper alloys strips, respectively.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129106747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present an application of the well-known frequency-domain modulus optimum criterion for obtaining settings of PID controller for the first order systems with dead time. The settings are obtained analytically for any value of the dead time parameter. Although the method usually gives very favourable closed-loop behaviour, in the case of large dead time the stability margin gets reduced and even non-stable behaviour can be observed. We propose a simple correction that preserves the stability margin, keeping maximum of the performance.
{"title":"PID control of FOPDT plants with dominant dead time - The frequency domain approach","authors":"J. Cvejn","doi":"10.1109/PC.2013.6581382","DOIUrl":"https://doi.org/10.1109/PC.2013.6581382","url":null,"abstract":"We present an application of the well-known frequency-domain modulus optimum criterion for obtaining settings of PID controller for the first order systems with dead time. The settings are obtained analytically for any value of the dead time parameter. Although the method usually gives very favourable closed-loop behaviour, in the case of large dead time the stability margin gets reduced and even non-stable behaviour can be observed. We propose a simple correction that preserves the stability margin, keeping maximum of the performance.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"312 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132311354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper proposes to reduce complexity of explicit MPC feedback laws by representing regions over which the law is defined as (possibly non-convex) polygons. Each polygon is then represented only by its boundaries, which reduces the memory footprint of the feedback law. Even though significant amount of memory can be saved this way, the price to be paid is increased computational load associated by performing point location tasks on non-convex objects. To reduce the computational requirements, we therefore propose to devise inner and outer convex approximations of non-convex polygons. Such approximations then allow to perform point location more effectively, leading to reduction of the required on-line computational effort. Several ways to design suitable approximations are presented and efficacy of the proposed procedure is evaluated.
{"title":"Simplification of explicit MPC solutions via inner and outer approximations","authors":"J. Oravec, Slavomir Blazek, M. Kvasnica","doi":"10.1109/PC.2013.6581442","DOIUrl":"https://doi.org/10.1109/PC.2013.6581442","url":null,"abstract":"The paper proposes to reduce complexity of explicit MPC feedback laws by representing regions over which the law is defined as (possibly non-convex) polygons. Each polygon is then represented only by its boundaries, which reduces the memory footprint of the feedback law. Even though significant amount of memory can be saved this way, the price to be paid is increased computational load associated by performing point location tasks on non-convex objects. To reduce the computational requirements, we therefore propose to devise inner and outer convex approximations of non-convex polygons. Such approximations then allow to perform point location more effectively, leading to reduction of the required on-line computational effort. Several ways to design suitable approximations are presented and efficacy of the proposed procedure is evaluated.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130973258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper presents an approach to PI controller design for time-delay systems which can be interpreted as systems with the interval parametric uncertainty. It is supposed that the controlled system is described by the transfer function with time-delay with parameters lying in certain intervals. The transfer function of the controlled system is modified by approximation of the time-delay term by its Pade expansion. PI controllers, that are able to assure robust stability of the feedback closed loop with the modified controlled system are found by the graphical method. Then the pole-placement method is used to specify those controller parameters, which assure certain quality of the control performance.
{"title":"Robust PI controller desing for a time-delay process","authors":"Katarína Matejičková, M. Bakosová","doi":"10.1109/PC.2013.6581457","DOIUrl":"https://doi.org/10.1109/PC.2013.6581457","url":null,"abstract":"The paper presents an approach to PI controller design for time-delay systems which can be interpreted as systems with the interval parametric uncertainty. It is supposed that the controlled system is described by the transfer function with time-delay with parameters lying in certain intervals. The transfer function of the controlled system is modified by approximation of the time-delay term by its Pade expansion. PI controllers, that are able to assure robust stability of the feedback closed loop with the modified controlled system are found by the graphical method. Then the pole-placement method is used to specify those controller parameters, which assure certain quality of the control performance.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126253742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Vasickaninova, M. Bakosová, M. Karšaiová, Jana Kmeťová
The paper deals with tuning of controllers for unstable plants. The controllers are presented for two types of plants: the unstable first order system and the unstable second order system, both with the uncertain plant gain. The control system design based on the algebraic approach using polynomials, the internal model control (IMC) structure and neuro-fuzzy inference system controller is used. The designed controllers are verified and compared by simulations on illustrative examples. The presented results show satisfactory control responses for the tracking of the step reference as well as for the step load disturbance attenuation.
{"title":"Methods for controller tuning for unstable systems","authors":"A. Vasickaninova, M. Bakosová, M. Karšaiová, Jana Kmeťová","doi":"10.1109/PC.2013.6581410","DOIUrl":"https://doi.org/10.1109/PC.2013.6581410","url":null,"abstract":"The paper deals with tuning of controllers for unstable plants. The controllers are presented for two types of plants: the unstable first order system and the unstable second order system, both with the uncertain plant gain. The control system design based on the algebraic approach using polynomials, the internal model control (IMC) structure and neuro-fuzzy inference system controller is used. The designed controllers are verified and compared by simulations on illustrative examples. The presented results show satisfactory control responses for the tracking of the step reference as well as for the step load disturbance attenuation.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131475089","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a 3D virtual laboratory presenting all features of advanced input shaping filter is described. By proper choice of filter coefficients, various design requirements can be achieved (damping at given frequencies, bandwidth, robustness to uncertainties, etc.). Hence, one can handle the trade-off between the filter performance and signal delay which is added to the loop. The filter principle can be evaluated on gantry crane 3D model by using virtual laboratory. The control aim is to avoid load oscillations during load transport. The shaping filter works as a band stop filter which attenuates the natural frequency by modifying setpoint changes. The 3D crane model development is based on Java3D package (rendering package) and a VRML (Virtual Reality Modeling Language) Java loader which creates a bridge between the CAD system and the rendering engine. The interactive tool is freely accessible at www.contlab.eu. The authors believe that the virtual lab may be useful for both academic and industrial sphere.
{"title":"Advanced input shaping filter 3D virtual laboratory","authors":"Jan Reitinger, M. Cech, M. Goubej","doi":"10.1109/PC.2013.6581465","DOIUrl":"https://doi.org/10.1109/PC.2013.6581465","url":null,"abstract":"In this paper, a 3D virtual laboratory presenting all features of advanced input shaping filter is described. By proper choice of filter coefficients, various design requirements can be achieved (damping at given frequencies, bandwidth, robustness to uncertainties, etc.). Hence, one can handle the trade-off between the filter performance and signal delay which is added to the loop. The filter principle can be evaluated on gantry crane 3D model by using virtual laboratory. The control aim is to avoid load oscillations during load transport. The shaping filter works as a band stop filter which attenuates the natural frequency by modifying setpoint changes. The 3D crane model development is based on Java3D package (rendering package) and a VRML (Virtual Reality Modeling Language) Java loader which creates a bridge between the CAD system and the rendering engine. The interactive tool is freely accessible at www.contlab.eu. The authors believe that the virtual lab may be useful for both academic and industrial sphere.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128131969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic model describing the FCC process is inspired from Lee and Groves model. The model uses three lump kinetics to describe the cracking reactions in the riser considered as a plug-flow system. The riser behavior is described by gasoil, gasoline, coke and energy balances as a plug flow reactor. The separator is considered as a CSTR. The regenerator mainly constituted by a dense and a dilute zone is also considered as a CSTR to represent the catalyst and its dynamic behavior is described by coke, oxygen and energy balances. This model is sufficiently complex to capture the major dynamic effects that occur in a FCC and to control the key variables which are the riser outlet temperature and the regenerator dense bed temperature. The manipulated inputs are the air inlet flow rate in the regenerator and the regenerated catalyst flow rate. Hard constraints are imposed with respect to the manipulated variables. In spite of the important nonlinearity of the FCC, Model Predictive Control is able to maintain a smooth multivariable control of the plant, while taking into account the constraints.
{"title":"Model predictive control of a fluid catalytic cracking unit","authors":"A. Boum, A. Latifi, J. Corriou","doi":"10.1109/PC.2013.6581433","DOIUrl":"https://doi.org/10.1109/PC.2013.6581433","url":null,"abstract":"The dynamic model describing the FCC process is inspired from Lee and Groves model. The model uses three lump kinetics to describe the cracking reactions in the riser considered as a plug-flow system. The riser behavior is described by gasoil, gasoline, coke and energy balances as a plug flow reactor. The separator is considered as a CSTR. The regenerator mainly constituted by a dense and a dilute zone is also considered as a CSTR to represent the catalyst and its dynamic behavior is described by coke, oxygen and energy balances. This model is sufficiently complex to capture the major dynamic effects that occur in a FCC and to control the key variables which are the riser outlet temperature and the regenerator dense bed temperature. The manipulated inputs are the air inlet flow rate in the regenerator and the regenerated catalyst flow rate. Hard constraints are imposed with respect to the manipulated variables. In spite of the important nonlinearity of the FCC, Model Predictive Control is able to maintain a smooth multivariable control of the plant, while taking into account the constraints.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"227 15","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133847857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper describes the first attempt to develop the software for computing the so-called flat output of the discrete-time nonlinear control system. The functions are implemented in NLControl, a package for nonlinear control systems, developed within the computer algebra system Mathematica. The implemented algorithm is quite elaborate. It involves the elements from the exterior differential calculus and from the theory of non-commutative polynomial rings, and requires solving large-scale systems of partial differential equations. At present the developed programs are only able to handle simple systems.
{"title":"Computation of flat outputs for discrete-time nonlinear systems with mathematica","authors":"K. Halturina, A. Kaldmae, U. Kotta, M. Tõnso","doi":"10.1109/PC.2013.6581392","DOIUrl":"https://doi.org/10.1109/PC.2013.6581392","url":null,"abstract":"The paper describes the first attempt to develop the software for computing the so-called flat output of the discrete-time nonlinear control system. The functions are implemented in NLControl, a package for nonlinear control systems, developed within the computer algebra system Mathematica. The implemented algorithm is quite elaborate. It involves the elements from the exterior differential calculus and from the theory of non-commutative polynomial rings, and requires solving large-scale systems of partial differential equations. At present the developed programs are only able to handle simple systems.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124740248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose three different Model Predictive Control (MPC) strategies for controlling temperatures in buildings. We show that maximization of thermal comfort, along with minimization of energy consumption, can be cast in various ways, each having their pros and cons. The three strategies include tracking of setpoint temperatures, tracking of a comfort zone, and minimization of number of violations of such a zone. Even though the latter formulation is the most demanding from a computational point of view, it indeed provides best thermal comfort. All proposed methods are compared with respect to two qualitative criteria on simulations.
{"title":"Comparison of MPC strategies for building control","authors":"Ján Drgoňa, M. Kvasnica","doi":"10.1109/PC.2013.6581444","DOIUrl":"https://doi.org/10.1109/PC.2013.6581444","url":null,"abstract":"We propose three different Model Predictive Control (MPC) strategies for controlling temperatures in buildings. We show that maximization of thermal comfort, along with minimization of energy consumption, can be cast in various ways, each having their pros and cons. The three strategies include tracking of setpoint temperatures, tracking of a comfort zone, and minimization of number of violations of such a zone. Even though the latter formulation is the most demanding from a computational point of view, it indeed provides best thermal comfort. All proposed methods are compared with respect to two qualitative criteria on simulations.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"207 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122786048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gain scheduling (GS) is one of the most popular approaches to nonlinear control design and it is known that GS controllers have better performance than robust controllers. Following the terminology in control engineering linear parameter-varying (LPV) systems are time-varying plants whose state space matrices are fixed functions of some vector of varying parameters. Our approach is based on considering the LPV system and scheduling parameter and their derivatives with respect to time are supposed to lie in a priori given hyper rectangles. For guarantee the performance we use the notion of guaranteed cost and optimised to given a cost function. The class of control structure includes decentralised fixed order output feedback like PID controller. Numerical examples illustrate the effectiveness of the proposed approach.
{"title":"Gain-scheduled controller design: Guaranteed quality approach","authors":"V. Veselý, Adrian Ilka","doi":"10.1109/PC.2013.6581453","DOIUrl":"https://doi.org/10.1109/PC.2013.6581453","url":null,"abstract":"Gain scheduling (GS) is one of the most popular approaches to nonlinear control design and it is known that GS controllers have better performance than robust controllers. Following the terminology in control engineering linear parameter-varying (LPV) systems are time-varying plants whose state space matrices are fixed functions of some vector of varying parameters. Our approach is based on considering the LPV system and scheduling parameter and their derivatives with respect to time are supposed to lie in a priori given hyper rectangles. For guarantee the performance we use the notion of guaranteed cost and optimised to given a cost function. The class of control structure includes decentralised fixed order output feedback like PID controller. Numerical examples illustrate the effectiveness of the proposed approach.","PeriodicalId":232418,"journal":{"name":"2013 International Conference on Process Control (PC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122796032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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