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Wei Ren - One of the best experts on this subject based on the ideXlab platform.

  • leader follower Consensus of linear multi agent systems with unknown external disturbances
    Systems & Control Letters, 2015
    Co-Authors: Weijun Cao, Wei Ren, Jinhui Zhang
    Abstract:

    Abstract This paper addresses the leader–follower Consensus tracking problem for multi-agent systems with identical general linear dynamics and unknown external disturbances. First, a distributed extended state observer is proposed, where both the local states and disturbance of each agent are estimated simultaneously by using the relative output information between neighbors. Then a Consensus Algorithm is proposed for each agent based on the relative estimated states between neighbors and its own disturbance estimate. It is shown that, with the proposed observer-based Consensus Algorithm, the leader–follower Consensus problem can be solved. Finally, we present a simulation example to demonstrate the effectiveness of the proposed Algorithm.

  • finite time Consensus for multi agent networks with unknown inherent nonlinear dynamics
    Automatica, 2014
    Co-Authors: Yongcan Cao, Wei Ren
    Abstract:

    The objective of this paper is to analyze the finite-time convergence of a nonlinear but continuous Consensus Algorithm for multi-agent networks with unknown inherent nonlinear dynamics. Due to the existence of the unknown inherent nonlinear dynamics, the stability analysis and the finite-time convergence analysis are more challenging than those under the well-studied Consensus Algorithms for known linear systems. For this purpose, we propose a novel comparison based tool. By using this tool, it is shown that the proposed nonlinear Consensus Algorithm can guarantee finite-time convergence if the directed switching interaction graph has a directed spanning tree at each time interval. Specifically, the finite-time convergence is shown by comparing the closed-loop system under the proposed Consensus Algorithm with some well-designed closed-loop system whose stability properties are easier to obtain. Moreover, the stability and the finite-time convergence of the closed-loop system using the proposed Consensus Algorithm under a (general) directed switching interaction graph can even be guaranteed by the stability and the finite-time convergence of some well-designed nonlinear closed-loop system under some special directed switching interaction graph. This provides a stimulating example for the potential applications of the proposed comparison based tool in the stability analysis of linear/nonlinear closed-loop systems by making use of known results in linear/nonlinear systems.

  • finite time Consensus for multi agent networks with unknown inherent nonlinear dynamics
    arXiv: Optimization and Control, 2013
    Co-Authors: Yongcan Cao, Wei Ren
    Abstract:

    This paper focuses on analyzing the finite-time convergence of a nonlinear Consensus Algorithm for multi-agent networks with unknown inherent nonlinear dynamics. Due to the existence of the unknown inherent nonlinear dynamics, the stability analysis and the finite-time convergence analysis of the closed-loop system under the proposed Consensus Algorithm are more challenging than those under the well-studied Consensus Algorithms for known linear systems. For this purpose, we propose a novel stability tool based on a generalized comparison lemma. With the aid of the novel stability tool, it is shown that the proposed nonlinear Consensus Algorithm can guarantee finite-time convergence if the directed switching interaction graph has a directed spanning tree at each time interval. Specifically, the finite-time convergence is shown by comparing the closed-loop system under the proposed Consensus Algorithm with some well-designed closed-loop system whose stability properties are easier to obtain. Moreover, the stability and the finite-time convergence of the closed-loop system using the proposed Consensus Algorithm under a (general) directed switching interaction graph can even be guaranteed by the stability and the finite-time convergence of some special well-designed nonlinear closed-loop system under some special directed switching interaction graph, where each agent has at most one neighbor whose state is either the maximum of those states that are smaller than its own state or the minimum of those states that are larger than its own state. This provides a stimulating example for the potential applications of the proposed novel stability tool in the stability analysis of linear/nonlinear closed-loop systems by making use of known results in linear/nonlinear systems. For illustration of the theoretical result, we provide a simulation example.

  • multi agent Consensus using both current and outdated states with fixed and undirected interaction
    Journal of Intelligent and Robotic Systems, 2010
    Co-Authors: Yongcan Cao, Wei Ren
    Abstract:

    We propose a distributed Consensus Algorithm for multi-agent systems. In contrast to the standard Consensus Algorithm that relies on only current states, the proposed Algorithm uses both current states and outdated states stored in memory. The proposed Algorithm is analyzed under an undirected communication graph. It is shown that the proposed Algorithm converges faster than the standard Consensus Algorithm while requiring identical maximum control effort if the outdated states are chosen properly. Simulation results demonstrate the effectiveness of the proposed Algorithm.

  • second order Consensus Algorithm with extensions to switching topologies and reference models
    American Control Conference, 2007
    Co-Authors: Wei Ren
    Abstract:

    In this paper, we extend the Consensus Algorithm for double integrator dynamics to the case that the information exchange topologies switch randomly with time and to the case that the final Consensus value evolves according to a given nonlinear reference model. We show sufficient conditions under which Consensus is reached under switching directed information exchange topologies. Unlike the Consensus Algorithm for single integrator dynamics, more stringent conditions are required to guarantee Consensus under switching directed topologies in the case of the Consensus Algorithm for double integrator dynamics. In addition, we propose Consensus Algorithms so that the information variables of each vehicle approach the solution of a nonlinear reference model when only a portion of the vehicles in the team have access to the model.

Mo-yuen Chow - One of the best experts on this subject based on the ideXlab platform.

  • incremental welfare Consensus Algorithm for cooperative distributed generation demand response in smart grid
    IEEE Transactions on Smart Grid, 2014
    Co-Authors: Navid Rahbariasr, Unnati Ojha, Ziang Zhang, Mo-yuen Chow
    Abstract:

    In this paper, we introduce the incremental welfare Consensus Algorithm for solving the energy management problem in a smart grid environment populated with distributed generators and responsive demands. The proposed Algorithm is distributed and cooperative such that it eliminates the need for a central energy-management unit, central price coordinator, or leader. The optimum energy solution is found through local peer-to-peer communications among smart devices. Each distributed generation unit is connected to a local price regulator, as is each consumer unit. In response to the price of energy proposed by the local price regulators, the power regulator on each generation/consumer unit determines the level of generation/consumption power needed to optimize the benefit of the device. The Consensus-based coordination among price regulators drives the behavior of the overall system toward the global optimum, despite the greedy behavior of each unit. The primary advantages of the proposed approach are: 1) convergence to the global optimum without requiring a central controller/coordinator or leader, despite the greedy behavior at the individual level and limited communications; and 2) scalability in terms of per-node computation and communications burden.

  • incremental welfare Consensus Algorithm for cooperative distributed generation demand response in smart grid
    IEEE Transactions on Smart Grid, 2014
    Co-Authors: Navid Rahbariasr, Unnati Ojha, Ziang Zhang, Mo-yuen Chow
    Abstract:

    In this paper, we introduce the incremental welfare Consensus Algorithm for solving the energy management problem in a smart grid environment populated with distributed generators and responsive demands. The proposed Algorithm is distributed and cooperative such that it eliminates the need for a central energy-management unit, central price coordinator, or leader. The optimum energy solution is found through local peer-to-peer communications among smart devices. Each distributed generation unit is connected to a local price regulator, as is each consumer unit. In response to the price of energy proposed by the local price regulators, the power regulator on each generation/consumer unit determines the level of generation/consumption power needed to optimize the benefit of the device. The Consensus-based coordination among price regulators drives the behavior of the overall system toward the global optimum, despite the greedy behavior of each unit. The primary advantages of the proposed approach are: 1) convergence to the global optimum without requiring a central controller/coordinator or leader, despite the greedy behavior at the individual level and limited communications; and 2) scalability in terms of per-node computation and communications burden.

  • decentralizing the economic dispatch problem using a two level incremental cost Consensus Algorithm in a smart grid environment
    North American Power Symposium, 2011
    Co-Authors: Ziang Zhang, Xichun Ying, Mo-yuen Chow
    Abstract:

    In a smart grid, effective distributed control Algorithms could be embedded in distributed controllers to properly allocate electrical power among connected buses autonomously. By selecting the incremental cost of each generation unit as the Consensus variable, the Incremental Cost Consensus (ICC) Algorithm can solve the economic dispatch problem in a distributed manner instead of using conventional centralized approaches. In this paper, we further decrease the requirement of the communication network by using an average Consensus Algorithm to acquire the system power mismatch information. The mathematical formulation of the Algorithms is also presented in this paper. In addition, the results of several case studies are presented to show the convergence rate of the ICC Algorithm and the comparison between the previous ICC and the new two-level ICC Algorithm.

  • incremental cost Consensus Algorithm in a smart grid environment
    Power and Energy Society General Meeting, 2011
    Co-Authors: Ziang Zhang, Mo-yuen Chow
    Abstract:

    In a next generation power system, effective distributed control Algorithms could be embedded in distributed controllers to properly allocate electrical power among connected buses autonomously. In this paper, we present a novel approach to solve the economic dispatch problem. By selecting the incremental cost of each generation unit as the Consensus variable, the Algorithm is able to solve the conventional centralized control problem in a distributed manner. The row-stochastic matrices have been used to indicate the different topologies of distribution systems and their configuration properties, such as convergence speeds. The simulation results of several case studies are provided to verify the Algorithm.

Parviz K Amid - One of the best experts on this subject based on the ideXlab platform.

  • an international Consensus Algorithm for management of chronic postoperative inguinal pain
    Hernia, 2015
    Co-Authors: Johan F M Lange, David C Chen, A R Wijsmuller, Rutger J Ploeg, J P E N Pierie, R Kaufmann, Parviz K Amid
    Abstract:

    Purpose Tension-free mesh repair of inguinal hernia has led to uniformly low recurrence rates. Morbidity associated with this operation is mainly related to chronic pain. No Consensus guidelines exist for the management of this condition. The goal of this study is to design an expert-based Algorithm for diagnostic and therapeutic management of chronic inguinal postoperative pain (CPIP).

  • an international Consensus Algorithm for management of chronic postoperative inguinal pain
    Hernia, 2015
    Co-Authors: Johan F M Lange, David C Chen, A R Wijsmuller, Rutger J Ploeg, J P E N Pierie, R Kaufmann, Parviz K Amid
    Abstract:

    Tension-free mesh repair of inguinal hernia has led to uniformly low recurrence rates. Morbidity associated with this operation is mainly related to chronic pain. No Consensus guidelines exist for the management of this condition. The goal of this study is to design an expert-based Algorithm for diagnostic and therapeutic management of chronic inguinal postoperative pain (CPIP). A group of surgeons considered experts on inguinal hernia surgery was solicited to develop the Algorithm. Consensus regarding each step of an Algorithm proposed by the authors was sought by means of the Delphi method leading to a revised expert-based Algorithm. With the input of 28 international experts, an Algorithm for a stepwise approach for management of CPIP was created. 26 participants accepted the final Algorithm as a Consensus model. One participant could not agree with the final concept. One expert did not respond during the final phase. There is a need for guidelines with regard to management of CPIP. This Algorithm can serve as a guide with regard to the diagnosis, management, and treatment of these patients and improve clinical outcomes. If an expectative phase of a few months has passed without any amelioration of CPIP, a multidisciplinary approach is indicated and a pain management team should be consulted. Pharmacologic, behavioral, and interventional modalities including nerve blocks are essential. If conservative measures fail and surgery is considered, triple neurectomy, correction for recurrence with or without neurectomy, and meshoma removal if indicated should be performed. Surgeons less experienced with remedial operations for CPIP should not hesitate to refer their patients to dedicated hernia surgeons.

Rutger J Ploeg - One of the best experts on this subject based on the ideXlab platform.

  • an international Consensus Algorithm for management of chronic postoperative inguinal pain
    Hernia, 2015
    Co-Authors: Johan F M Lange, David C Chen, A R Wijsmuller, Rutger J Ploeg, J P E N Pierie, R Kaufmann, Parviz K Amid
    Abstract:

    Purpose Tension-free mesh repair of inguinal hernia has led to uniformly low recurrence rates. Morbidity associated with this operation is mainly related to chronic pain. No Consensus guidelines exist for the management of this condition. The goal of this study is to design an expert-based Algorithm for diagnostic and therapeutic management of chronic inguinal postoperative pain (CPIP).

  • an international Consensus Algorithm for management of chronic postoperative inguinal pain
    Hernia, 2015
    Co-Authors: Johan F M Lange, David C Chen, A R Wijsmuller, Rutger J Ploeg, J P E N Pierie, R Kaufmann, Parviz K Amid
    Abstract:

    Tension-free mesh repair of inguinal hernia has led to uniformly low recurrence rates. Morbidity associated with this operation is mainly related to chronic pain. No Consensus guidelines exist for the management of this condition. The goal of this study is to design an expert-based Algorithm for diagnostic and therapeutic management of chronic inguinal postoperative pain (CPIP). A group of surgeons considered experts on inguinal hernia surgery was solicited to develop the Algorithm. Consensus regarding each step of an Algorithm proposed by the authors was sought by means of the Delphi method leading to a revised expert-based Algorithm. With the input of 28 international experts, an Algorithm for a stepwise approach for management of CPIP was created. 26 participants accepted the final Algorithm as a Consensus model. One participant could not agree with the final concept. One expert did not respond during the final phase. There is a need for guidelines with regard to management of CPIP. This Algorithm can serve as a guide with regard to the diagnosis, management, and treatment of these patients and improve clinical outcomes. If an expectative phase of a few months has passed without any amelioration of CPIP, a multidisciplinary approach is indicated and a pain management team should be consulted. Pharmacologic, behavioral, and interventional modalities including nerve blocks are essential. If conservative measures fail and surgery is considered, triple neurectomy, correction for recurrence with or without neurectomy, and meshoma removal if indicated should be performed. Surgeons less experienced with remedial operations for CPIP should not hesitate to refer their patients to dedicated hernia surgeons.

B Zinman - One of the best experts on this subject based on the ideXlab platform.

  • management of hyperglycaemia in type 2 diabetes mellitus a Consensus Algorithm for the initiation and adjustment of therapy
    Diabetologia, 2009
    Co-Authors: David M Nathan, John B Buse, Mayer B Davidson, Eleuterio Ferrannini, R R Holman, Robert S Sherwin, B Zinman
    Abstract:

    The Consensus Algorithm for the medical management of type 2 diabetes was published in August 2006 with the expectation that it would be updated, based on the availability of new interventions and new evidence to establish their clinical role. The authors continue to endorse the principles used to develop the Algorithm and its major features. We are sensitive to the risks of changing the Algorithm cavalierly or too frequently, without compelling new information. An update to the Consensus Algorithm published in January 2008 specifically addressed safety issues surrounding the thiazolidinediones. In this revision, we focus on the new classes of medications that now have more clinical data and experience.

  • medical management of hyperglycemia in type 2 diabetes a Consensus Algorithm for the initiation and adjustment of therapy a Consensus statement of the american diabetes association and the european association for the study of diabetes
    Diabetes Care, 2009
    Co-Authors: David M Nathan, John B Buse, Mayer B Davidson, R R Holman, Robert S Sherwin, Ele Ferrannini, B Zinman
    Abstract:

    The Consensus Algorithm for the medical management of type 2 diabetes was published in August 2006 with the expectation that it would be updated, based on the availability of new interventions and new evidence to establish their clinical role. The authors continue to endorse the principles used to develop the Algorithm and its major features. We are sensitive to the risks of changing the Algorithm cavalierly or too frequently, without compelling new information. An update to the Consensus Algorithm published in January 2008 specifically addressed safety issues surrounding the thiazolidinediones. In this revision, we focus on the new classes of medications that now have more clinical data and experience.

  • medical management of hyperglycaemia in type 2 diabetes mellitus a Consensus Algorithm for the initiation and adjustment of therapy a Consensus statement from the american diabetes association and the european association for the study of diabetes
    Diabetologia, 2009
    Co-Authors: David M Nathan, John B Buse, Mayer B Davidson, Eleuterio Ferrannini, R R Holman, Robert S Sherwin, B Zinman
    Abstract:

    The Consensus Algorithm for the medical management of type 2 diabetes was published in August 2006 with the expectation that it would be updated, based on the availability of new interventions and new evidence to establish their clinical role. The authors continue to endorse the principles used to develop the Algorithm and its major features. We are sensitive to the risks of changing the Algorithm cavalierly or too frequently, without compelling new information. An update to the Consensus Algorithm published in January 2008 specifically addressed safety issues surrounding the thiazolidinediones. In this revision, we focus on the new classes of medications that now have more clinical data and experience.

  • medical management of hyperglycemia in type 2 diabetes a Consensus Algorithm for the initiation and adjustment of therapy a Consensus statement of the american diabetes association and the european association for the study of diabetes
    Diabetes Spectrum, 2009
    Co-Authors: David M Nathan, John B Buse, Mayer B Davidson, R R Holman, Robert S Sherwin, Ele Ferrannini, B Zinman
    Abstract:

    The Consensus Algorithm for the medical management of type 2 diabetes was published in August 2006 with the expectation that it would be updated, based on the availability of new interventions and new evidence to establish their clinical role. The authors continue to endorse the principles used to develop the Algorithm and its major features. We are sensitive to the risks of changing the Algorithm cavalierly or too frequently, without compelling new information. An update to the Consensus Algorithm published in January 2008 specifically addressed safety issues surrounding the thiazolidinediones. In this revision, we focus on the new classes of medications that now have more clinical data and experience. Diabetes Care 32:193–203, 2009 The epidemic of type 2 diabetes and the recognition that achieving specific glycemic goals can substantially reduce morbidity have made the effective treatment of hyperglycemia a top priority.1–3 While the management of hyperglycemia, the hallmark metabolic abnormality associated with type 2 diabetes, has historically taken center stage in the treatment of diabetes, therapies directed at other coincident features, such as dyslipidemia, hypertension, hypercoagulability, obesity, and insulin resistance, have also been a major focus of research and therapy. Maintaining glycemic levels as close to the nondiabetic range as possible has been demonstrated to have a powerful beneficial effect on diabetes-specific microvascular complications, including retinopathy, nephropathy, and neuropathy, in the setting of type 1 diabetes;4,5 in type 2 diabetes, more intensive treatment strategies have likewise been demonstrated to reduce microvascular complications.6–8 Intensive glycemic management resulting in lower A1C levels has also been shown to have a beneficial effect on cardiovascular disease (CVD) complications in type 1 diabetes;9,10 however, current studies have failed to demonstrate a beneficial effect of intensive diabetes therapy on CVD in type 2 diabetes. …

  • management of hyperglycemia in type 2 diabetes a Consensus Algorithm for the initiation and adjustment of therapy update regarding thiazolidinediones a Consensus statement from the american diabetes association and the european association for the study of diabetes
    Diabetes Care, 2008
    Co-Authors: David M Nathan, John B Buse, Mayer B Davidson, R R Holman, Robert S Sherwin, Ele Ferrannini, B Zinman
    Abstract:

    The Consensus Algorithm for the management of type 2 diabetes was developed on behalf of the American Diabetes Association and the European Association for the Study of Diabetes approximately 1 year ago (1,2). This evidence-based Algorithm was developed to help guide health care providers to choose the most appropriate treatment regimens from an ever-expanding list of approved medications. The authors continue to endorse the major features of the Algorithm, including the need to achieve and maintain glycemia within or as close to the nondiabetic range as is safely possible, the initiation of lifestyle interventions and treatment with metformin at the time of diagnosis, the rapid addition of medications and transition to new regimens when target glycemia is not achieved, and the early addition of insulin therapy in patients who do not meet target A1C levels. The availability of newly approved medications and the accrual of new clinical trial and other data should inform the Algorithm. In this update, we primarily address one important issue that has received much recent attention: our current understanding of the advantages and disadvantages of the thiazolidinediones. In addition, we have revised the original Table 1 to include the dipeptidylpeptidase-4 inhibitor sitagliptin, which was not approved by the U.S. Food and Drug Administration at the time of our original publication (Table 1). We are mindful of the importance of not changing this Consensus guideline in …