Pub Date : 2001-11-11DOI: 10.1115/imece2001/dsc-24554
R. Kashani, Asim S. Mohammad
Synthesis and analysis of model-based controllers for an acoustic system require the state-space formulation of the system. The use of modal data, i.e. resonant frequencies, model damping ratios, and mode shapes, in constructing state-space model of an aoucstic system is described in this paper. Moreover, a simple, low-order feedback controller for adding damping to and/or cancelling offending noise in an acoustic system is introduced. State-space modeling, as well as the effectiveness of the proposed feedback controller are demonstrated through numerical and experimental, illustrative examples.
{"title":"State-Space Modeling and Control of Acoustic Systems","authors":"R. Kashani, Asim S. Mohammad","doi":"10.1115/imece2001/dsc-24554","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24554","url":null,"abstract":"\u0000 Synthesis and analysis of model-based controllers for an acoustic system require the state-space formulation of the system. The use of modal data, i.e. resonant frequencies, model damping ratios, and mode shapes, in constructing state-space model of an aoucstic system is described in this paper. Moreover, a simple, low-order feedback controller for adding damping to and/or cancelling offending noise in an acoustic system is introduced. State-space modeling, as well as the effectiveness of the proposed feedback controller are demonstrated through numerical and experimental, illustrative examples.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"2013 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87732209","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24586
Heng Xu, K. Danai, S. Malkin
A method for optimal control of cylindrical plunge grinding cycles is introduced. Unlike conventional cycles which have a few pre-determined sequential steps with discrete infeed rates, the new method will continually vary the infeed velocity. The proposed method utilizes the Model Predictive Control (MPC) approach whereby the control action at each sampling instant is selected in accordance with its effect on the future values of process variables and part quality attributes. This paper describes the problem and presents some preliminary results. It also discusses the difficulties that will need to be overcome before the controller can be implemented on-line.
{"title":"Methodology for Continuous Infeed Cylindrical Plunge Grinding","authors":"Heng Xu, K. Danai, S. Malkin","doi":"10.1115/imece2001/dsc-24586","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24586","url":null,"abstract":"\u0000 A method for optimal control of cylindrical plunge grinding cycles is introduced. Unlike conventional cycles which have a few pre-determined sequential steps with discrete infeed rates, the new method will continually vary the infeed velocity. The proposed method utilizes the Model Predictive Control (MPC) approach whereby the control action at each sampling instant is selected in accordance with its effect on the future values of process variables and part quality attributes. This paper describes the problem and presents some preliminary results. It also discusses the difficulties that will need to be overcome before the controller can be implemented on-line.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"80 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89561965","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24604
Josu Agirrebeitia Zelaia, Rafael Avilés González, Igor Fernández de Bustos, E. Martin
The present article looks at a method of analysing the behaviour of highly redundant multibody systems (e.g. in the case of cellular adaptive structures of variable geometry) in environments with obstacles. It is sought to solve the inverse problem in successive positions of variable-geometry structures, avoiding the obstacles in its work environment; i.e. the computation of the increment that has to be assigned to the actuators throughout the movement of the multibody system so that it does not collide with obstacles, as one or more nodes perform a pre-established function (e.g. a certain path). The multibody systems are modelled via rod-type finite elements, both deformable and indeformable, and the coordinates of their nodes are chosen as variables. The obstacles are modelled via a mesh of points that exert repulsive forces on the nodes of the multibody, so that interference between the two is avoided. Such forces have been chosen inversely proportional to the Nth power of the distance between the corresponding points of the obstacle and of the multibody system. The method is based on a potential function and on its minimization using the Lagrange Multiplier Method. The solution of the resulting equations is undertaken iteratively with the Newton-Raphson Method. The 2D and 3D examples provided attest to the good performance of the algorithms and procedure here set forth.
{"title":"A Method for the Study of Position in Highly Redundant Multibody Systems in Environments With Obstacles","authors":"Josu Agirrebeitia Zelaia, Rafael Avilés González, Igor Fernández de Bustos, E. Martin","doi":"10.1115/imece2001/dsc-24604","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24604","url":null,"abstract":"\u0000 The present article looks at a method of analysing the behaviour of highly redundant multibody systems (e.g. in the case of cellular adaptive structures of variable geometry) in environments with obstacles. It is sought to solve the inverse problem in successive positions of variable-geometry structures, avoiding the obstacles in its work environment; i.e. the computation of the increment that has to be assigned to the actuators throughout the movement of the multibody system so that it does not collide with obstacles, as one or more nodes perform a pre-established function (e.g. a certain path). The multibody systems are modelled via rod-type finite elements, both deformable and indeformable, and the coordinates of their nodes are chosen as variables. The obstacles are modelled via a mesh of points that exert repulsive forces on the nodes of the multibody, so that interference between the two is avoided. Such forces have been chosen inversely proportional to the Nth power of the distance between the corresponding points of the obstacle and of the multibody system. The method is based on a potential function and on its minimization using the Lagrange Multiplier Method. The solution of the resulting equations is undertaken iteratively with the Newton-Raphson Method. The 2D and 3D examples provided attest to the good performance of the algorithms and procedure here set forth.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"46 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76728393","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24608
D. Economou, I. Antoniadis
A method is proposed for the suppression both of the transient as well as the residual sway of suspended payloads, including also cases where hoisting occurs during the payload transfer motion. The proposed method is based on the preconditioning of the inputs to the system by digital filtering the input function. Conventional FIR or IIR digital filters can be used for the preconditioning approach. The method is demonstrated in the case of a suspended load carried by a gantry crane. Extensive simulation results clearly verify the effectiveness of the approach.
{"title":"Sway Suppression of Suspended Payloads With Hoisting Using Digital Filters","authors":"D. Economou, I. Antoniadis","doi":"10.1115/imece2001/dsc-24608","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24608","url":null,"abstract":"\u0000 A method is proposed for the suppression both of the transient as well as the residual sway of suspended payloads, including also cases where hoisting occurs during the payload transfer motion. The proposed method is based on the preconditioning of the inputs to the system by digital filtering the input function. Conventional FIR or IIR digital filters can be used for the preconditioning approach. The method is demonstrated in the case of a suspended load carried by a gantry crane. Extensive simulation results clearly verify the effectiveness of the approach.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81008533","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24595
D. Siljak, D. Stipanović
A decentralized control law is called autonomous if the resulting closed-loop interconnected system is connectively stable, that is, the system remains stable despite structural perturbations whereby subsystems are disconnected and again connected in an unpredictable way during operation. The objective of the paper is to propose an LMI scheme for design of autonomous decentralized controllers and observers for output control of complex systems. An interesting feature of the proposed observer-based controllers is that they do not impose any communication overhead since only the locally available output information is required.
{"title":"Autonomous Decentralized Control","authors":"D. Siljak, D. Stipanović","doi":"10.1115/imece2001/dsc-24595","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24595","url":null,"abstract":"\u0000 A decentralized control law is called autonomous if the resulting closed-loop interconnected system is connectively stable, that is, the system remains stable despite structural perturbations whereby subsystems are disconnected and again connected in an unpredictable way during operation. The objective of the paper is to propose an LMI scheme for design of autonomous decentralized controllers and observers for output control of complex systems. An interesting feature of the proposed observer-based controllers is that they do not impose any communication overhead since only the locally available output information is required.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"61 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79613120","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24535
Perry Y. Li, P. Bjegovic, S. Ramaswamy
Many manufacturing processes involve the successive processing of the substrate at multiple station on a transport medium, with the hope that at the end of the process, the product has the desired property. Paper manufacturing is an example in which over 90% of the water from pulp is sequentially removed through gravity, vacuum dewatering, pressing, and thermal drying. The consistency and uniformity of the moisture content at the end of process is important for paper quality. Current strategy for the control of moisture content uses a feedback sensor at the end of the process to adjust the dryers. This introduces a long deadtime and causes excessive use of the dryers, which translate to limitations in performance, robustness and inefficient energy usage. In this paper, we investigate a new control approach in which in-process moisture contents are estimated using air-flow as surrogate measurements, and the pressure settings in the multiple vacuum dewatering boxes are adjusted according to the surrogate measurements. A preemptive control algorithm is developed which has the ability to decouple and eliminate the effects of the disturbances that occur upstream in the process from downstream. Robustness analysis and simulation studies suggest that as long as the surrogate measurements are accurate, the proposed control scheme will be robust and accurate.
{"title":"Preemptive Control of Multiply Actuated Processes: Application to Moisture Content Control in Paper Manufacturing Using Surrogate Measurements","authors":"Perry Y. Li, P. Bjegovic, S. Ramaswamy","doi":"10.1115/imece2001/dsc-24535","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24535","url":null,"abstract":"\u0000 Many manufacturing processes involve the successive processing of the substrate at multiple station on a transport medium, with the hope that at the end of the process, the product has the desired property. Paper manufacturing is an example in which over 90% of the water from pulp is sequentially removed through gravity, vacuum dewatering, pressing, and thermal drying. The consistency and uniformity of the moisture content at the end of process is important for paper quality. Current strategy for the control of moisture content uses a feedback sensor at the end of the process to adjust the dryers. This introduces a long deadtime and causes excessive use of the dryers, which translate to limitations in performance, robustness and inefficient energy usage. In this paper, we investigate a new control approach in which in-process moisture contents are estimated using air-flow as surrogate measurements, and the pressure settings in the multiple vacuum dewatering boxes are adjusted according to the surrogate measurements. A preemptive control algorithm is developed which has the ability to decouple and eliminate the effects of the disturbances that occur upstream in the process from downstream. Robustness analysis and simulation studies suggest that as long as the surrogate measurements are accurate, the proposed control scheme will be robust and accurate.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82630044","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24542
A. Schrempf, L. Re, W. Groißböck, E. Lughofer, E. Klement, G. Frizberg
Fast detection of abnormal plant operation is critical for many applications. Fault detection requires some kind of comparison between actual and “normal” behavior, which implies the use of models. Exact modeling of engine systems is probably impossible and even middle-complexity models are very time-consuming. In some few cases, as for on board diagnostics, the very limited amount of cases to be treated and the usually large production volumes allow to develop models suitable to detect an abnormal behavior, but, in general, however, this approach cannot be followed. As fast detection of abnormal plant operation is often critical, alternative low-effort approaches are required. This paper presents a procedure suitable for engine fault detection based on parallel automatic modeling. It is shown that this approach yields a flexible and reliable tool for automatic modeling for this goal, while keeping the effort for the operator rather low.
{"title":"Automatic Engine Modeling for Failure Detection","authors":"A. Schrempf, L. Re, W. Groißböck, E. Lughofer, E. Klement, G. Frizberg","doi":"10.1115/imece2001/dsc-24542","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24542","url":null,"abstract":"\u0000 Fast detection of abnormal plant operation is critical for many applications. Fault detection requires some kind of comparison between actual and “normal” behavior, which implies the use of models. Exact modeling of engine systems is probably impossible and even middle-complexity models are very time-consuming. In some few cases, as for on board diagnostics, the very limited amount of cases to be treated and the usually large production volumes allow to develop models suitable to detect an abnormal behavior, but, in general, however, this approach cannot be followed. As fast detection of abnormal plant operation is often critical, alternative low-effort approaches are required. This paper presents a procedure suitable for engine fault detection based on parallel automatic modeling. It is shown that this approach yields a flexible and reliable tool for automatic modeling for this goal, while keeping the effort for the operator rather low.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"181 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83018757","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24606
J. Cheong, Y. Youm, W. Chung
In the slewing multi-link flexible robot systems, the natural frequencies and mode shapes have been determined using the assumed component mode method with clamped-joint condition, in which the system modes is reconstructed by the series of assumed modes of each link. This method, however, requires large number of assumed modes to accurately describe the system and even more, sometimes, the results are erroneous. The direct analytic solution of entire system vibration mode which is a comparative concept of assumed mode method can accurately account for the entire vibration with a few number of significant modes. This paper deals with system vibration modes of two-link flexible robot and their appropriate boundary conditions. There are four possible set of boundary conditions, that is, clamped-clamped, clamped-spring, spring-clamped, spring-spring, according to joint servo condition, and we compare mode shapes and modal frequencies of each case by numerical and experimental results. We also provide important characteristics of natural mode when imposed certain kind of boundary conditions.
{"title":"Investigation and Comparison of Possible Boundary Conditions and System Vibration Modes in Two-Link Flexible Manipulators","authors":"J. Cheong, Y. Youm, W. Chung","doi":"10.1115/imece2001/dsc-24606","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24606","url":null,"abstract":"\u0000 In the slewing multi-link flexible robot systems, the natural frequencies and mode shapes have been determined using the assumed component mode method with clamped-joint condition, in which the system modes is reconstructed by the series of assumed modes of each link. This method, however, requires large number of assumed modes to accurately describe the system and even more, sometimes, the results are erroneous. The direct analytic solution of entire system vibration mode which is a comparative concept of assumed mode method can accurately account for the entire vibration with a few number of significant modes.\u0000 This paper deals with system vibration modes of two-link flexible robot and their appropriate boundary conditions. There are four possible set of boundary conditions, that is, clamped-clamped, clamped-spring, spring-clamped, spring-spring, according to joint servo condition, and we compare mode shapes and modal frequencies of each case by numerical and experimental results. We also provide important characteristics of natural mode when imposed certain kind of boundary conditions.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83223862","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24572
D. Tarraf, H. Asada
The subject of this paper is online identification of systems described by linearly parametrized models, under the assumption that the parameters in question are slowly time varying, and with the requirement that the normal operation of the system is left completely undisturbed by the estimation procedure. A Lyapunov-based parameter estimator design for a class of LP systems is presented, assuming that we have no control over any of the system inputs, including control inputs. The estimation is guaranteed to converge provided good knowledge of extreme scenarios is available and provided certain observability-like requirements, derived in the paper, are met. The proposed design procedure is interpreted in the light of observer design for an ‘envelope’, augmented system where the parameters to be estimated are treated as slow state variables. Illustrative numerical examples follow; Good performance is observed both for the idealized case and for the case where sensor noise is present.
{"title":"Non-Disruptive Online Identification of Linearly Parametrized Systems","authors":"D. Tarraf, H. Asada","doi":"10.1115/imece2001/dsc-24572","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24572","url":null,"abstract":"\u0000 The subject of this paper is online identification of systems described by linearly parametrized models, under the assumption that the parameters in question are slowly time varying, and with the requirement that the normal operation of the system is left completely undisturbed by the estimation procedure. A Lyapunov-based parameter estimator design for a class of LP systems is presented, assuming that we have no control over any of the system inputs, including control inputs. The estimation is guaranteed to converge provided good knowledge of extreme scenarios is available and provided certain observability-like requirements, derived in the paper, are met. The proposed design procedure is interpreted in the light of observer design for an ‘envelope’, augmented system where the parameters to be estimated are treated as slow state variables. Illustrative numerical examples follow; Good performance is observed both for the idealized case and for the case where sensor noise is present.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83098662","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 : 2001-11-11DOI: 10.1115/imece2001/dsc-24538
O. Beldiman, L. Bushnell, G. Walsh, Hua O. Wang, Yiguang Hong
In this paper we study the effect of external perturbations on a networked control system. We start by assuming that the non-networked system without perturbation is exponentially stable. Then, for fast enough networks we show that if the perturbation is bounded the networked system is ultimately bounded and if the perturbation is vanishing then the networked system is asymptotically stable. We conclude the paper with simulations verifying the results.
{"title":"Perturbations in Networked Control Systems","authors":"O. Beldiman, L. Bushnell, G. Walsh, Hua O. Wang, Yiguang Hong","doi":"10.1115/imece2001/dsc-24538","DOIUrl":"https://doi.org/10.1115/imece2001/dsc-24538","url":null,"abstract":"\u0000 In this paper we study the effect of external perturbations on a networked control system. We start by assuming that the non-networked system without perturbation is exponentially stable. Then, for fast enough networks we show that if the perturbation is bounded the networked system is ultimately bounded and if the perturbation is vanishing then the networked system is asymptotically stable. We conclude the paper with simulations verifying the results.","PeriodicalId":90691,"journal":{"name":"Proceedings of the ASME Dynamic Systems and Control Conference. ASME Dynamic Systems and Control Conference","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89701912","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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