For an automated transportation system, like the PRT system or IVHS, an efficient vehicle-merging algorithm is required for smooth operation management of merging, collision avoidance between vehicles, ride comfort, and the effect on traffic should be considered. This paper proposes an unmanned vehicle merging algorithm that consists of two procedures. First, a longitudinal control algorithm is designed to keep a safe headway between vehicles in a single lane. Next, "vacant slot and ghost vehicle" concept is introduced and a decision algorithm is designed to determine the sequence of vehicles entering a converging section considering total traffic flow. The sequencing algorithm is based on fuzzy rules and the membership functions are determined first by an intuitive method and then trained by a learning method using neural net. The vehicle-merging algorithm is shown to be effective through simulations based on a PRT model.
{"title":"Neuro-fuzzy control of converging vehicles for automated transportation systems","authors":"Jahng-Hyon Park, Se-Hee Ryu","doi":"10.1109/ACC.1999.786348","DOIUrl":"https://doi.org/10.1109/ACC.1999.786348","url":null,"abstract":"For an automated transportation system, like the PRT system or IVHS, an efficient vehicle-merging algorithm is required for smooth operation management of merging, collision avoidance between vehicles, ride comfort, and the effect on traffic should be considered. This paper proposes an unmanned vehicle merging algorithm that consists of two procedures. First, a longitudinal control algorithm is designed to keep a safe headway between vehicles in a single lane. Next, \"vacant slot and ghost vehicle\" concept is introduced and a decision algorithm is designed to determine the sequence of vehicles entering a converging section considering total traffic flow. The sequencing algorithm is based on fuzzy rules and the membership functions are determined first by an intuitive method and then trained by a learning method using neural net. The vehicle-merging algorithm is shown to be effective through simulations based on a PRT model.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133491627","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}
Output feedback controllers for disturbance attenuation of linear systems with constraints on input amplitudes and rates are studied. The main features include guaranteed performance levels that depend on both actuator magnitude and rate limits, and controllers that operate at, or close to, maximum actuator capacity. The controllers have a structure similar to those used in the LPV approach.
{"title":"Output feedback controllers for disturbance attenuation with actuator amplitude and rate saturation","authors":"Thanh Huu Nguyen, F. Jabbari","doi":"10.1109/ACC.1999.786223","DOIUrl":"https://doi.org/10.1109/ACC.1999.786223","url":null,"abstract":"Output feedback controllers for disturbance attenuation of linear systems with constraints on input amplitudes and rates are studied. The main features include guaranteed performance levels that depend on both actuator magnitude and rate limits, and controllers that operate at, or close to, maximum actuator capacity. The controllers have a structure similar to those used in the LPV approach.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"316 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116602266","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}
Invariant sets can be used in conjunction with known control laws to guarantee convergence of linear time varying (LTV) or uncertain systems with constraints. However, invariant sets are often associated with fixed control laws and hence can be limited in size by constraints. It is shown how to utilise degrees of freedom in the transient predictions in order to enlarge the invariant set and so widen the applicability of the convergence proof, for a given control law. The same degrees of freedom allow for computationally efficient and systematic performance optimisation.
{"title":"Efficient robust predictive control","authors":"B. Kouvaritakis, J. Rossiter, J. Schuurmans","doi":"10.1109/ACC.1999.786372","DOIUrl":"https://doi.org/10.1109/ACC.1999.786372","url":null,"abstract":"Invariant sets can be used in conjunction with known control laws to guarantee convergence of linear time varying (LTV) or uncertain systems with constraints. However, invariant sets are often associated with fixed control laws and hence can be limited in size by constraints. It is shown how to utilise degrees of freedom in the transient predictions in order to enlarge the invariant set and so widen the applicability of the convergence proof, for a given control law. The same degrees of freedom allow for computationally efficient and systematic performance optimisation.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116543805","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 application of optimal reactive power flow (ORPF) to the New Brunswick (NB) power system is presented. The potential benefits and the real-time implementation problems of ORPF are discussed. Some important issues on real-time implementation of ORPF such as frequency of running, the number of activated control variables, and the order of adjustment of different controls are discussed. The application of ORPF on the NE Power network has shown two major benefits: 1) an improvement in the voltage profile and voltage stability, and 2) a savings in active power loss. The improvement in voltage profile can cause fewer violations and a more stable system from the voltage point of view, A reduction in active power loss gained from ORPF can save a significant amount of money. The total ideal saving for the year 1995 predicted in the study was in excess of $900,000, however, only ten to thirty percent of this amount is realistically obtainable due to operational and other constraints. These savings can be gained simultaneously with the improvement of the voltage profiles.
{"title":"Real-time implementation of optimal reactive power flow","authors":"S. Sharif, J.H. Taylor","doi":"10.1109/ACC.1999.786350","DOIUrl":"https://doi.org/10.1109/ACC.1999.786350","url":null,"abstract":"The application of optimal reactive power flow (ORPF) to the New Brunswick (NB) power system is presented. The potential benefits and the real-time implementation problems of ORPF are discussed. Some important issues on real-time implementation of ORPF such as frequency of running, the number of activated control variables, and the order of adjustment of different controls are discussed. The application of ORPF on the NE Power network has shown two major benefits: 1) an improvement in the voltage profile and voltage stability, and 2) a savings in active power loss. The improvement in voltage profile can cause fewer violations and a more stable system from the voltage point of view, A reduction in active power loss gained from ORPF can save a significant amount of money. The total ideal saving for the year 1995 predicted in the study was in excess of $900,000, however, only ten to thirty percent of this amount is realistically obtainable due to operational and other constraints. These savings can be gained simultaneously with the improvement of the voltage profiles.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"191 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133360958","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 method is presented for the output-feedback control of discrete-time linear systems with hard constraints on state and control variables. Prior work has shown that optimal controllers for constrained systems take the form of a nonlinear feedback law acting on a set-valued state estimate. In this paper, conventional state estimation schemes are used. A nonlinear control law is derived which views the state estimation error as a disturbance. The resulting control law is then used in conjunction with the conventional observer, rather than set-valued observer, to achieve the desired constrained regulation. The significantly reduced real-time computations come at the cost of restricting the controller structure and thereby introducing possible conservatism in the achievable performance. The results are specialized to the problem of anti-windup for systems with control saturations. A "measurement governor" scheme is introduced that alters plant measurements in such a way to improve performance in the presence of controller saturations.
{"title":"Anti-windup via constrained regulation with observers","authors":"J. Shamma","doi":"10.1109/ACC.1999.786496","DOIUrl":"https://doi.org/10.1109/ACC.1999.786496","url":null,"abstract":"A method is presented for the output-feedback control of discrete-time linear systems with hard constraints on state and control variables. Prior work has shown that optimal controllers for constrained systems take the form of a nonlinear feedback law acting on a set-valued state estimate. In this paper, conventional state estimation schemes are used. A nonlinear control law is derived which views the state estimation error as a disturbance. The resulting control law is then used in conjunction with the conventional observer, rather than set-valued observer, to achieve the desired constrained regulation. The significantly reduced real-time computations come at the cost of restricting the controller structure and thereby introducing possible conservatism in the achievable performance. The results are specialized to the problem of anti-windup for systems with control saturations. A \"measurement governor\" scheme is introduced that alters plant measurements in such a way to improve performance in the presence of controller saturations.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129489994","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 global optimization algorithm for solving bilinear matrix inequalities (BMI) problems is developed. It is based on a dual Lagrange formulation for computing lower bounds that are used in a branching procedure to eliminate partition sets in the space of nonconvex variables. The advantage of the proposed method is twofold. First, lower bound computations reduce to solving easily tractable linear matrix inequality (LMI) problems. Secondly, the lower bounding procedure guarantees global convergence of the algorithm when combined with an exhaustive partitioning of the space of nonconvex variables. Another important feature is that the branching phase takes place in the space of nonconvex variables only, hence limiting the overall cost of the algorithm. Also, an important point in the method is that separated LMI constraints are encapsulated into an augmented BMI for improving the lower bound computations. Applications of the algorithm to robust structure/controller design are considered.
{"title":"A new Lagrangian dual global optimization algorithm for solving bilinear matrix inequalities","authors":"H. Tuan, P. Apkarian, Y. Nakashima","doi":"10.1109/ACC.1999.786170","DOIUrl":"https://doi.org/10.1109/ACC.1999.786170","url":null,"abstract":"A global optimization algorithm for solving bilinear matrix inequalities (BMI) problems is developed. It is based on a dual Lagrange formulation for computing lower bounds that are used in a branching procedure to eliminate partition sets in the space of nonconvex variables. The advantage of the proposed method is twofold. First, lower bound computations reduce to solving easily tractable linear matrix inequality (LMI) problems. Secondly, the lower bounding procedure guarantees global convergence of the algorithm when combined with an exhaustive partitioning of the space of nonconvex variables. Another important feature is that the branching phase takes place in the space of nonconvex variables only, hence limiting the overall cost of the algorithm. Also, an important point in the method is that separated LMI constraints are encapsulated into an augmented BMI for improving the lower bound computations. Applications of the algorithm to robust structure/controller design are considered.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128567529","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 problem of estimating the parameters for continuous-time partially observed systems is discussed. New exact filters for obtaining maximum likelihood (ML) parameter estimates via the expectation maximization algorithm are derived. The methodology exploits relations between incomplete and complete data likelihood and gradient of likelihood functions, which are derived using Girsanov's measure transformations. The ML parameter estimates are described by a set of Lyapunov sensitivity equations.
{"title":"Maximum likelihood parameter estimation from incomplete data via the sensitivity equations: the continuous-time case","authors":"C. Charalambous, A. Logothetis","doi":"10.1109/ACC.1999.782398","DOIUrl":"https://doi.org/10.1109/ACC.1999.782398","url":null,"abstract":"The problem of estimating the parameters for continuous-time partially observed systems is discussed. New exact filters for obtaining maximum likelihood (ML) parameter estimates via the expectation maximization algorithm are derived. The methodology exploits relations between incomplete and complete data likelihood and gradient of likelihood functions, which are derived using Girsanov's measure transformations. The ML parameter estimates are described by a set of Lyapunov sensitivity equations.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129035556","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 focus on modeling and control of an aerosol flow reactor used to produce titania powder. We initially derive a fundamental mathematical model for the process that accounts for simultaneous chemical reaction, nucleation, Brownian and turbulent coagulation and convective transport. The model is subsequently used to synthesise a nonlinear output feedback controller which manipulates the temperature of the reactor wall to achieve an aerosol size distribution in the outlet of the reactor with desired geometric average particle diameter. The nonlinear controller is successfully implemented on the detailed process model and is shown to deal effectively with external disturbances.
{"title":"Modeling and control of a titania aerosol reactor","authors":"A. Kalani, P. Christofides","doi":"10.1109/ACC.1999.786316","DOIUrl":"https://doi.org/10.1109/ACC.1999.786316","url":null,"abstract":"We focus on modeling and control of an aerosol flow reactor used to produce titania powder. We initially derive a fundamental mathematical model for the process that accounts for simultaneous chemical reaction, nucleation, Brownian and turbulent coagulation and convective transport. The model is subsequently used to synthesise a nonlinear output feedback controller which manipulates the temperature of the reactor wall to achieve an aerosol size distribution in the outlet of the reactor with desired geometric average particle diameter. The nonlinear controller is successfully implemented on the detailed process model and is shown to deal effectively with external disturbances.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121167085","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 simple approach for disturbance attenuation in multivariable linear systems via dynamical output compensators is proposed based on complete parametric eigenstructure assignment. The basic idea is to minimise the H/sub 2/ norm of the disturbance-output transfer function using the design freedom provided by eigenstructure assignment. The closed-loop eigenvalues are also optimised within desired regions on the left-half complex plane. Application of the proposed approach to robust control of a magnetic bearing is considered.
{"title":"Disturbance attenuation in linear systems via dynamical compensators-a parametric eigenstructure assignment approach","authors":"G. Duan, G. Irwin, G.P. Liu","doi":"10.1109/ACC.1999.786403","DOIUrl":"https://doi.org/10.1109/ACC.1999.786403","url":null,"abstract":"A simple approach for disturbance attenuation in multivariable linear systems via dynamical output compensators is proposed based on complete parametric eigenstructure assignment. The basic idea is to minimise the H/sub 2/ norm of the disturbance-output transfer function using the design freedom provided by eigenstructure assignment. The closed-loop eigenvalues are also optimised within desired regions on the left-half complex plane. Application of the proposed approach to robust control of a magnetic bearing is considered.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117214311","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 study robustness properties of a class of digital feedback control systems with time-varying sampling periods consisting of an interconnection of a continuous-time nonlinear plant (described by systems of first-order ordinary differential equations), a nonlinear digital controller (described by systems of first-order ordinary difference equations), and appropriate interface elements between the plant and controller (A/D and D/A converters). For such systems, we establish results for exponential stability of an equilibrium (in the Lyapunov sense) in the presence of vanishing perturbations and for the boundedness of solutions (i.e., Lagrange stability) under the influence of non-vanishing perturbations. We apply these results to the study of quantization effects.
{"title":"Robustness analysis of digital feedback control systems with time-varying sampling periods","authors":"Bo Hu, A. Michel","doi":"10.1109/ACC.1999.782413","DOIUrl":"https://doi.org/10.1109/ACC.1999.782413","url":null,"abstract":"We study robustness properties of a class of digital feedback control systems with time-varying sampling periods consisting of an interconnection of a continuous-time nonlinear plant (described by systems of first-order ordinary differential equations), a nonlinear digital controller (described by systems of first-order ordinary difference equations), and appropriate interface elements between the plant and controller (A/D and D/A converters). For such systems, we establish results for exponential stability of an equilibrium (in the Lyapunov sense) in the presence of vanishing perturbations and for the boundedness of solutions (i.e., Lagrange stability) under the influence of non-vanishing perturbations. We apply these results to the study of quantization effects.","PeriodicalId":441363,"journal":{"name":"Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123260033","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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