医疗机构现有数据库存储的单一性和集中性,使得电子医疗数据的安全性、完整性和可追溯性无法得到保证,从而导致患者的医疗隐私受到威胁。虽然已有研究提出了基于云存储等数据安全存储的方案,但是其需要依赖一个完全可信的第三方来保证...医疗机构现有数据库存储的单一性和集中性,使得电子医疗数据的安全性、完整性和可追溯性无法得到保证,从而导致患者的医疗隐私受到威胁。虽然已有研究提出了基于云存储等数据安全存储的方案,但是其需要依赖一个完全可信的第三方来保证交互的可靠性。为此,文中提出了去中心化的区块链信息管理方案来实现医疗数据的安全存储。该方案采用了改进PBFT共识算法和优化Hash加密算法,将医疗数据安全有效地存储于分布式数据库中,保证了医疗数据的完整性和可追溯性;同时,设计了全新的数据交互系统来阻止第三方与数据库的直接交互,以防止不可信的第三方恶意破坏医疗数据,保证了数据的安全性;最后,通过访问控制与Lucene检索机制保护患者的隐私并实现医疗数据的快速检索。实验分析表明,相较于工作量证明(Proof of Work,POW)、股份授权证明(Delegated Proof of Stake,DPOS)等算法,改进的PBFT共识算法为医疗区块链系统提供了更优的稳定性和吞吐量;相比于普通的数据库交互,数据交互系统有效地阻止了对数据库的直接操作,具有较好的安全性和防篡改性。实验数据表明,去中心化的医疗数据存储系统、改进的PBFT共识算法以及数据交互系统的架构,实现了医疗数据的安全、可追溯和防篡改,解决了医疗数据集中存储、不可追溯和易受攻击等难点,为进一步推动区块链技术应用于医疗信息行业的发展奠定了基础。展开更多
The paper develops a novel framework of consensus control with fault-estimation-in-the-loop for multi-agent systems(MASs)in the presence of faults.A dynamic event-triggered protocol(DETP)by adding an auxiliary variabl...The paper develops a novel framework of consensus control with fault-estimation-in-the-loop for multi-agent systems(MASs)in the presence of faults.A dynamic event-triggered protocol(DETP)by adding an auxiliary variable is utilized to improve the utilization of communication resources.First,a novel estimator with a noise bias is put forward to estimate the existed fault and then a consensus controller with fault compensation(FC)is adopted to realize the demand of reliability and safety of addressed MASs.Subsequently,a novel consensus control framework with fault-estimation-in-the-loop is developed to achieve the predetermined consensus performance with the l_(2)-l_(∞)constraint by employing the variance analysis and the Lyapunov stability approaches.Furthermore,the desired estimator and controller gains are obtained in light of the solution to an algebraic matrix equation and a linear matrix inequality in a recursive way,respectively.Finally,a simulation result is employed to verify the usefulness of the proposed design framework.展开更多
Multi-agent systems(MASs)are typically composed of multiple smart entities with independent sensing,communication,computing,and decision-making capabilities.Nowadays,MASs have a wide range of applications in smart gri...Multi-agent systems(MASs)are typically composed of multiple smart entities with independent sensing,communication,computing,and decision-making capabilities.Nowadays,MASs have a wide range of applications in smart grids,smart manufacturing,sensor networks,and intelligent transportation systems.Control of the MASs are often coordinated through information interaction among agents,which is one of the most important factors affecting coordination and cooperation performance.However,unexpected physical faults and cyber attacks on a single agent may spread to other agents via information interaction very quickly,and thus could lead to severe degradation of the whole system performance and even destruction of MASs.This paper is concerned with the safety/security analysis and synthesis of MASs arising from physical faults and cyber attacks,and our goal is to present a comprehensive survey on recent results on fault estimation,detection,diagnosis and fault-tolerant control of MASs,and cyber attack detection and secure control of MASs subject to two typical cyber attacks.Finally,the paper concludes with some potential future research topics on the security issues of MASs.展开更多
This paper addresses the cooperative control problem of multiple unmanned aerial vehicles(multi-UAV)systems.First,a new distributed consensus algorithm for second-order nonlinear multi-agent systems(MAS)is formulated ...This paper addresses the cooperative control problem of multiple unmanned aerial vehicles(multi-UAV)systems.First,a new distributed consensus algorithm for second-order nonlinear multi-agent systems(MAS)is formulated under the leader-following approach.The algorithm provides smooth input signals to the agents’control channels,which avoids the chattering effect generated by the conventional sliding mode-based control protocols.Second,a new formation control scheme is developed by integrating smooth distributed consensus control protocols into the geometric pattern model to achieve three-dimensional formation tracking.The Lyapunov theory is used to prove the stability and convergence of both distributed consensus and formation controllers.The effectiveness of the proposed algorithms is demonstrated through simulation results.展开更多
We propose a formation control strategy for multiple unmanned aerial vehicles （multi-UAV） based on second-order consensus, by introducing position and velocity coordination variables through neighbor-to-neighbor int...We propose a formation control strategy for multiple unmanned aerial vehicles （multi-UAV） based on second-order consensus, by introducing position and velocity coordination variables through neighbor-to-neighbor interaction to generate steering commands. A cooperative guidance algorithm and a cooperative control algorithm are proposed together to maintain a specified geometric configuration, managing the position and attitude respectively. With the whole system composed of the six-degree-of-freedom UAV model, tile cooperative guidance algorithm, and the cooperative control algorithm, the formation control strategy is a closed-loop one and with full states. The cooperative guidance law is a second-order consensus algorithm, providing the desired acceleration, pitch rate, and heading rate. Longitudinal and lateral motions are jointly considered, and the cooperative control law is designed by deducing state equations. Closed-loop stability of the formation is analyzed, and a necessary and sufficient condition is provided. Measurement errors in position data are suppressed by synchronization technology to improve the control precision. In the simulation, three-dimensional formation flight demonstrates the feasibility and effectiveness of the formation control strategy.展开更多
In this paper, the leader-following tracking problem of fractional-order multi-agent systems is addressed. The dynamics of each agent may be heterogeneous and has unknown nonlinearities. By assumptions that the intera...In this paper, the leader-following tracking problem of fractional-order multi-agent systems is addressed. The dynamics of each agent may be heterogeneous and has unknown nonlinearities. By assumptions that the interaction topology is undirected and connected and the unknown nonlinear uncertain dynamics can be parameterized by a neural network, an adaptive learning law is proposed to deal with unknown nonlinear dynamics, based on which a kind of cooperative tracking protocols are constructed. The feedback gain matrix is obtained to solve an algebraic Riccati equation. To construct the fully distributed cooperative tracking protocols, the adaptive law is also adopted to adjust the coupling weight. With the developed control laws,we can prove that all signals in the closed-loop systems are guaranteed to be uniformly ultimately bounded. Finally, a simple simulation example is provided to illustrate the established result.展开更多
文摘医疗机构现有数据库存储的单一性和集中性,使得电子医疗数据的安全性、完整性和可追溯性无法得到保证,从而导致患者的医疗隐私受到威胁。虽然已有研究提出了基于云存储等数据安全存储的方案,但是其需要依赖一个完全可信的第三方来保证交互的可靠性。为此,文中提出了去中心化的区块链信息管理方案来实现医疗数据的安全存储。该方案采用了改进PBFT共识算法和优化Hash加密算法,将医疗数据安全有效地存储于分布式数据库中,保证了医疗数据的完整性和可追溯性;同时,设计了全新的数据交互系统来阻止第三方与数据库的直接交互,以防止不可信的第三方恶意破坏医疗数据,保证了数据的安全性;最后,通过访问控制与Lucene检索机制保护患者的隐私并实现医疗数据的快速检索。实验分析表明,相较于工作量证明(Proof of Work,POW)、股份授权证明(Delegated Proof of Stake,DPOS)等算法,改进的PBFT共识算法为医疗区块链系统提供了更优的稳定性和吞吐量;相比于普通的数据库交互,数据交互系统有效地阻止了对数据库的直接操作,具有较好的安全性和防篡改性。实验数据表明,去中心化的医疗数据存储系统、改进的PBFT共识算法以及数据交互系统的架构,实现了医疗数据的安全、可追溯和防篡改,解决了医疗数据集中存储、不可追溯和易受攻击等难点,为进一步推动区块链技术应用于医疗信息行业的发展奠定了基础。
基金supported in part by the Australian Research Council Discovery Early Career Researcher Award(DE200101128)。
文摘The paper develops a novel framework of consensus control with fault-estimation-in-the-loop for multi-agent systems(MASs)in the presence of faults.A dynamic event-triggered protocol(DETP)by adding an auxiliary variable is utilized to improve the utilization of communication resources.First,a novel estimator with a noise bias is put forward to estimate the existed fault and then a consensus controller with fault compensation(FC)is adopted to realize the demand of reliability and safety of addressed MASs.Subsequently,a novel consensus control framework with fault-estimation-in-the-loop is developed to achieve the predetermined consensus performance with the l_(2)-l_(∞)constraint by employing the variance analysis and the Lyapunov stability approaches.Furthermore,the desired estimator and controller gains are obtained in light of the solution to an algebraic matrix equation and a linear matrix inequality in a recursive way,respectively.Finally,a simulation result is employed to verify the usefulness of the proposed design framework.
基金partially supported by the National Natural Science Foundation of China(61873237)the Fundamental Research Funds for the Central Universities+2 种基金the Fundamental Research Funds for the Provincial Universities of Zhejiang(RF-A2019003)the Research Grants Council of the Hong Kong Special Administrative Region of China(City U/11204315)the Hong Kong Scholars Program(XJ2016030)。
文摘Multi-agent systems(MASs)are typically composed of multiple smart entities with independent sensing,communication,computing,and decision-making capabilities.Nowadays,MASs have a wide range of applications in smart grids,smart manufacturing,sensor networks,and intelligent transportation systems.Control of the MASs are often coordinated through information interaction among agents,which is one of the most important factors affecting coordination and cooperation performance.However,unexpected physical faults and cyber attacks on a single agent may spread to other agents via information interaction very quickly,and thus could lead to severe degradation of the whole system performance and even destruction of MASs.This paper is concerned with the safety/security analysis and synthesis of MASs arising from physical faults and cyber attacks,and our goal is to present a comprehensive survey on recent results on fault estimation,detection,diagnosis and fault-tolerant control of MASs,and cyber attack detection and secure control of MASs subject to two typical cyber attacks.Finally,the paper concludes with some potential future research topics on the security issues of MASs.
基金This work was supported by the Deanship of Scientific Research(DSR)at King Abdulaziz University,Jeddah(G-363-135-1438).
文摘This paper addresses the cooperative control problem of multiple unmanned aerial vehicles(multi-UAV)systems.First,a new distributed consensus algorithm for second-order nonlinear multi-agent systems(MAS)is formulated under the leader-following approach.The algorithm provides smooth input signals to the agents’control channels,which avoids the chattering effect generated by the conventional sliding mode-based control protocols.Second,a new formation control scheme is developed by integrating smooth distributed consensus control protocols into the geometric pattern model to achieve three-dimensional formation tracking.The Lyapunov theory is used to prove the stability and convergence of both distributed consensus and formation controllers.The effectiveness of the proposed algorithms is demonstrated through simulation results.
基金supported by the National Natural Science Foundation of China(No.61473229)the Special Fund for Basic Scientific Research of Central Colleges,Chang’an University,China(Nos.310832163403 and 310832161012)+1 种基金the Key Science and Technology Program of Shaanxi Province,China(No.2017JQ6060)the Xi’an Science and Technology Plan,China(No.CXY1512-3)
文摘We propose a formation control strategy for multiple unmanned aerial vehicles （multi-UAV） based on second-order consensus, by introducing position and velocity coordination variables through neighbor-to-neighbor interaction to generate steering commands. A cooperative guidance algorithm and a cooperative control algorithm are proposed together to maintain a specified geometric configuration, managing the position and attitude respectively. With the whole system composed of the six-degree-of-freedom UAV model, tile cooperative guidance algorithm, and the cooperative control algorithm, the formation control strategy is a closed-loop one and with full states. The cooperative guidance law is a second-order consensus algorithm, providing the desired acceleration, pitch rate, and heading rate. Longitudinal and lateral motions are jointly considered, and the cooperative control law is designed by deducing state equations. Closed-loop stability of the formation is analyzed, and a necessary and sufficient condition is provided. Measurement errors in position data are suppressed by synchronization technology to improve the control precision. In the simulation, three-dimensional formation flight demonstrates the feasibility and effectiveness of the formation control strategy.
基金supported by the National Natural Science Foundation of China(61303211)Zhejiang Provincial Natural Science Foundation of China(LY17F030003,LY15F030009)
文摘In this paper, the leader-following tracking problem of fractional-order multi-agent systems is addressed. The dynamics of each agent may be heterogeneous and has unknown nonlinearities. By assumptions that the interaction topology is undirected and connected and the unknown nonlinear uncertain dynamics can be parameterized by a neural network, an adaptive learning law is proposed to deal with unknown nonlinear dynamics, based on which a kind of cooperative tracking protocols are constructed. The feedback gain matrix is obtained to solve an algebraic Riccati equation. To construct the fully distributed cooperative tracking protocols, the adaptive law is also adopted to adjust the coupling weight. With the developed control laws,we can prove that all signals in the closed-loop systems are guaranteed to be uniformly ultimately bounded. Finally, a simple simulation example is provided to illustrate the established result.
