Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547804
F. Bayat, T. Johansen, A. Jalali
The online computational burden of linear model predictive control (MPC) can be moved offline by using multi-parametric programming, so called explicit MPC. The explicit MPC is a piecewise affine (PWA) function defined over a polyhedral subdivision of the set of feasible states. The online evaluation of such a control law needs to determine the polyhedral region in which the current state lies. This procedure is called the point location problem and its computational complexity is challenging. In this paper a new flexible algorithm is proposed which enables the designer to tradeoff between time and storage complexities. Utilizing the concept of hash tables and the associate hash functions the proposed method is modified to solve an aggregated point location problem in processing complexity independent of the number of polyhedral regions while the storage needs remains tractable. The effectiveness of this approach is supported by several numerical examples.
{"title":"Managing time-storage complexity in point location problem: Application to explicit model predictive control","authors":"F. Bayat, T. Johansen, A. Jalali","doi":"10.1109/MED.2010.5547804","DOIUrl":"https://doi.org/10.1109/MED.2010.5547804","url":null,"abstract":"The online computational burden of linear model predictive control (MPC) can be moved offline by using multi-parametric programming, so called explicit MPC. The explicit MPC is a piecewise affine (PWA) function defined over a polyhedral subdivision of the set of feasible states. The online evaluation of such a control law needs to determine the polyhedral region in which the current state lies. This procedure is called the point location problem and its computational complexity is challenging. In this paper a new flexible algorithm is proposed which enables the designer to tradeoff between time and storage complexities. Utilizing the concept of hash tables and the associate hash functions the proposed method is modified to solve an aggregated point location problem in processing complexity independent of the number of polyhedral regions while the storage needs remains tractable. The effectiveness of this approach is supported by several numerical examples.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130343547","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547611
P. Ignaciuk, A. Bartoszewicz
In systems with deterministic and constant delay Smith predictor offers a very efficient method for compensating dead-time. However, it is vulnerable to model uncertainties and parameter changes, in particular to delay variations. In this paper, we provide an alternative solution for compensating dead-time in systems with uncertain and time-varying delay. Two compensator structures are proposed - one for linear systems with known nominal delay (and unknown variation pattern), and another for nonlinear plants and/or systems with unknown delay. The proposed solutions retain conceptual simplicity of the traditional Smith compensator and are applicable to a large variety of control problems as demonstrated in case studies.
{"title":"Dead-time compensation through direct input measurement in systems with unknown time-varying delay","authors":"P. Ignaciuk, A. Bartoszewicz","doi":"10.1109/MED.2010.5547611","DOIUrl":"https://doi.org/10.1109/MED.2010.5547611","url":null,"abstract":"In systems with deterministic and constant delay Smith predictor offers a very efficient method for compensating dead-time. However, it is vulnerable to model uncertainties and parameter changes, in particular to delay variations. In this paper, we provide an alternative solution for compensating dead-time in systems with uncertain and time-varying delay. Two compensator structures are proposed - one for linear systems with known nominal delay (and unknown variation pattern), and another for nonlinear plants and/or systems with unknown delay. The proposed solutions retain conceptual simplicity of the traditional Smith compensator and are applicable to a large variety of control problems as demonstrated in case studies.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124333810","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547874
D. Ichalal, B. Marx, J. Ragot, D. Maquin
A new actuator fault tolerant control strategy is proposed for nonlinear Takagi-Sugeno (T-S) systems. The control law aims to compensate the actuator faults and allows the system states to track a reference corresponding to a fault free situation. The design of such a control law requires the knowledge of the faults, this task is achieved with a proportional integral observer (PIO). The robust stability of the system with the fault tolerant control law is analyzed with the Lyapunov theory and the ℒ2 optimization. Sufficient stability conditions are obtained in terms of linear matrix inequalities (LMIs). The gains of the FTC are obtained by solving these LMIs. A simulation example is finally proposed.
{"title":"Observer based actuator fault tolerant control for nonlinear Takagi-Sugeno systems : an LMI approach","authors":"D. Ichalal, B. Marx, J. Ragot, D. Maquin","doi":"10.1109/MED.2010.5547874","DOIUrl":"https://doi.org/10.1109/MED.2010.5547874","url":null,"abstract":"A new actuator fault tolerant control strategy is proposed for nonlinear Takagi-Sugeno (T-S) systems. The control law aims to compensate the actuator faults and allows the system states to track a reference corresponding to a fault free situation. The design of such a control law requires the knowledge of the faults, this task is achieved with a proportional integral observer (PIO). The robust stability of the system with the fault tolerant control law is analyzed with the Lyapunov theory and the ℒ2 optimization. Sufficient stability conditions are obtained in terms of linear matrix inequalities (LMIs). The gains of the FTC are obtained by solving these LMIs. A simulation example is finally proposed.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124374154","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547677
M. Bouattour, M. Chadli, A. El Hajjaji, M. Chaabane
In this paper, a robust fault detection observer is designed for a class of nonlinear systems described by T-S (Takagi-Sugeno) fuzzy model with sensor faults and unknown bounded disturbances. The method uses the technique of descriptor systems by considering sensor faults as an auxiliary state variables. The basic idea of our study is to formulate the robust fault detection observer design as a H-/H∞ problem. A solution of the considered problem is then given via a Linear Matrix Inequality (LMI) formulation. The considered robust fault detection observer design problem is solved with a given sufficient conditions based on an iterative LMI procedure.
{"title":"Robust fault detection observer design for Takagi-Sugeno systems: A descriptor approach","authors":"M. Bouattour, M. Chadli, A. El Hajjaji, M. Chaabane","doi":"10.1109/MED.2010.5547677","DOIUrl":"https://doi.org/10.1109/MED.2010.5547677","url":null,"abstract":"In this paper, a robust fault detection observer is designed for a class of nonlinear systems described by T-S (Takagi-Sugeno) fuzzy model with sensor faults and unknown bounded disturbances. The method uses the technique of descriptor systems by considering sensor faults as an auxiliary state variables. The basic idea of our study is to formulate the robust fault detection observer design as a H-/H∞ problem. A solution of the considered problem is then given via a Linear Matrix Inequality (LMI) formulation. The considered robust fault detection observer design problem is solved with a given sufficient conditions based on an iterative LMI procedure.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124277293","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547762
A. Benaicha, G. Mourot, Mohamed Guerfel, K. BenOthman, J. Ragot
In this paper, a new method is proposed to determine the structure of PCA models for system diagnosis. This method based on the principle of variable reconstruction determines PCA models in order to optimize detection and isolation of simple and multiple faults affecting redundant or non redundant variables. This new method has been validated by a simulation example of a nonlinear system.
{"title":"A new method for determining PCA models for system diagnosis","authors":"A. Benaicha, G. Mourot, Mohamed Guerfel, K. BenOthman, J. Ragot","doi":"10.1109/MED.2010.5547762","DOIUrl":"https://doi.org/10.1109/MED.2010.5547762","url":null,"abstract":"In this paper, a new method is proposed to determine the structure of PCA models for system diagnosis. This method based on the principle of variable reconstruction determines PCA models in order to optimize detection and isolation of simple and multiple faults affecting redundant or non redundant variables. This new method has been validated by a simulation example of a nonlinear system.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134462164","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547666
R. Gessing
It is shown that for strongly nonlinear plants taken from MATLAB Neural Network (NN) Control Systems Demos, the conventional controllers PD and P, which fulfill the demands of formulated in the paper the Criterion RD1 (Relative Degree =1), are significantly better then NN controllers appearing in these Demos. Moreover the conventional controllers operate well for significantly larger changes of the reference signal without the need of their re-tuning.
{"title":"Whether and when the conventional controllers may operate well with nonlinear plants","authors":"R. Gessing","doi":"10.1109/MED.2010.5547666","DOIUrl":"https://doi.org/10.1109/MED.2010.5547666","url":null,"abstract":"It is shown that for strongly nonlinear plants taken from MATLAB Neural Network (NN) Control Systems Demos, the conventional controllers PD and P, which fulfill the demands of formulated in the paper the Criterion RD1 (Relative Degree =1), are significantly better then NN controllers appearing in these Demos. Moreover the conventional controllers operate well for significantly larger changes of the reference signal without the need of their re-tuning.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"27 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133291883","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547741
Guoqing Zhang, M. Xie, Hejin Yang, Jing Li, Xuepei Wu
Design of the locomotion control system for the LOCH robot is presented in this paper. Gait planning and control algorithm for uneven terrain is also considered. The LOCH robot is an adult-sized biped humanoid robot. It adopts the distributed control structure based on CAN bus, and uses a Linux operating system as the software platform. The architecture of both the hardware and software system is introduced. The emphasis is then put onto the biped planning and control. An on-line planner is designed on the basis of the inverted arm model. It generates walking gaits adaptively according to user inputs and floor flatness changes. In handling uneven floor, an imaginary foot approach is proposed to convert the problem into flat floor planning. Stability control and compliant landing control are also investigated. Both experiments and simulations are performed to show the effectiveness of the proposed design.
{"title":"Locomotion control system design for the LOCH humanoid robot","authors":"Guoqing Zhang, M. Xie, Hejin Yang, Jing Li, Xuepei Wu","doi":"10.1109/MED.2010.5547741","DOIUrl":"https://doi.org/10.1109/MED.2010.5547741","url":null,"abstract":"Design of the locomotion control system for the LOCH robot is presented in this paper. Gait planning and control algorithm for uneven terrain is also considered. The LOCH robot is an adult-sized biped humanoid robot. It adopts the distributed control structure based on CAN bus, and uses a Linux operating system as the software platform. The architecture of both the hardware and software system is introduced. The emphasis is then put onto the biped planning and control. An on-line planner is designed on the basis of the inverted arm model. It generates walking gaits adaptively according to user inputs and floor flatness changes. In handling uneven floor, an imaginary foot approach is proposed to convert the problem into flat floor planning. Stability control and compliant landing control are also investigated. Both experiments and simulations are performed to show the effectiveness of the proposed design.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114189514","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547807
A. Sala
A fairly general class of nonlinear plants can be modeled as as a time-varying polytopic combination of “vertex” linear systems also known as Takagi-Sugeno fuzzy systems. As many linear LMI control results naturally generalize to such systems, LMI formulations for TS control became the tool of choice in the 1990s. Important results have since been obtained, although significant sources of conservativeness remain. Using a Taylor-series formalism, a polytopic combination of polynomials can be used to describe such nonlinear systems. The sum-of-squares paradigm can be used for such polytopic polynomial systems. This paper reviews the main motivation behind such modelling techniques and the sources of conservatism of control designs based on the linear vertex models instead of the original nonlinear equations. The reader is referred to [31] for further discussion.
{"title":"The polytopic/fuzzy polynomial approach for non-linear control: Advantages and drawbacks","authors":"A. Sala","doi":"10.1109/MED.2010.5547807","DOIUrl":"https://doi.org/10.1109/MED.2010.5547807","url":null,"abstract":"A fairly general class of nonlinear plants can be modeled as as a time-varying polytopic combination of “vertex” linear systems also known as Takagi-Sugeno fuzzy systems. As many linear LMI control results naturally generalize to such systems, LMI formulations for TS control became the tool of choice in the 1990s. Important results have since been obtained, although significant sources of conservativeness remain. Using a Taylor-series formalism, a polytopic combination of polynomials can be used to describe such nonlinear systems. The sum-of-squares paradigm can be used for such polytopic polynomial systems. This paper reviews the main motivation behind such modelling techniques and the sources of conservatism of control designs based on the linear vertex models instead of the original nonlinear equations. The reader is referred to [31] for further discussion.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115662076","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547763
U. Nurges, S. Avanessov
The geometry of stable discrete polynomials using their coefficients and reflection coefficients is investigated. Stable polytopes of different reflection vector sets are defined and the volume of these stable polytopes is calculated.
{"title":"Stable polytope of reflection vector sets","authors":"U. Nurges, S. Avanessov","doi":"10.1109/MED.2010.5547763","DOIUrl":"https://doi.org/10.1109/MED.2010.5547763","url":null,"abstract":"The geometry of stable discrete polynomials using their coefficients and reflection coefficients is investigated. Stable polytopes of different reflection vector sets are defined and the volume of these stable polytopes is calculated.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115370209","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}
Pub Date : 2010-06-23DOI: 10.1109/MED.2010.5547773
S. Boubaker, M. Djemai, N. Manamanni, F. M'sahli
Many control applications in real-world processes require accurate models for the active system. In particular, hybrid systems which are defined as an interaction of continuous dynamics, usually described by differential equations, and discrete dynamics, described through switching sequences. Note that the sub-models of a hybrid system are activated alternatively by a switching rule which indicates the active sub-model at each time instant. Nowadays, the estimation of both the time-interval in which a sub-model is active and the parameters of such sub-model is an important issue. In fact, it allows suitable choice of the operating modes in a real process. Hence, the hybrid identification problem is a challenging task due to the inherent nonconvexity of the prediction-error function according to the parameters to be identified. In this paper, the Particle Swarm Optimization (PSO) technique is exploited to locate the switching instants of Autonomous Switched Linear Systems (ASLS) and to estimate the parameters of the sub-models only by using measurements from the real process. Then, statistical validations are proposed to show the efficiency of the framework through a literature benchmark.
{"title":"Identification of Autonomous Switched Linear Systems: A Particle Swarm Optimization approach","authors":"S. Boubaker, M. Djemai, N. Manamanni, F. M'sahli","doi":"10.1109/MED.2010.5547773","DOIUrl":"https://doi.org/10.1109/MED.2010.5547773","url":null,"abstract":"Many control applications in real-world processes require accurate models for the active system. In particular, hybrid systems which are defined as an interaction of continuous dynamics, usually described by differential equations, and discrete dynamics, described through switching sequences. Note that the sub-models of a hybrid system are activated alternatively by a switching rule which indicates the active sub-model at each time instant. Nowadays, the estimation of both the time-interval in which a sub-model is active and the parameters of such sub-model is an important issue. In fact, it allows suitable choice of the operating modes in a real process. Hence, the hybrid identification problem is a challenging task due to the inherent nonconvexity of the prediction-error function according to the parameters to be identified. In this paper, the Particle Swarm Optimization (PSO) technique is exploited to locate the switching instants of Autonomous Switched Linear Systems (ASLS) and to estimate the parameters of the sub-models only by using measurements from the real process. Then, statistical validations are proposed to show the efficiency of the framework through a literature benchmark.","PeriodicalId":149864,"journal":{"name":"18th Mediterranean Conference on Control and Automation, MED'10","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123846642","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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