In networked control system (NCS) where control loop is closed over communication network, limited data rate may deteriorate control performance even destabilize the control system. In this paper, performance analysis...In networked control system (NCS) where control loop is closed over communication network, limited data rate may deteriorate control performance even destabilize the control system. In this paper, performance analysis of a typical second-order control system with data rate constraints is conducted, and the concept of critical data rate (CDR) is presented. In order to find the CDR in NCS, an approximate searching method is proposed to guarantee acceptable control performance.展开更多
为了提高控制器局域网络(controller area network,CAN)通信的实时性,文章基于时间触发CAN(time-triggered CAN,TTCAN)协议,采用verilog硬件描述语言设计实现TTCAN总线控制器。该控制器可在经典CAN模式与TTCAN模式之间进行切换,同时兼...为了提高控制器局域网络(controller area network,CAN)通信的实时性,文章基于时间触发CAN(time-triggered CAN,TTCAN)协议,采用verilog硬件描述语言设计实现TTCAN总线控制器。该控制器可在经典CAN模式与TTCAN模式之间进行切换,同时兼容可变速率CAN(CAN with flexible data rate,CAN FD)协议下的高速通信。实验结果证明,相较于经典CAN总线控制器,该TTCAN总线控制器能够减少在高总线负载率下周期性报文的发送延时,在全波特率范围内且总线负载率大于等于60%的情况下,能够减少75%以上的CAN报文发送延时。展开更多
Controller area networks(CANs),as one of the widely used fieldbuses in the industry,have been extended to the automation field with strict standards for safety and reliability.In practice,factors such as fatigue and i...Controller area networks(CANs),as one of the widely used fieldbuses in the industry,have been extended to the automation field with strict standards for safety and reliability.In practice,factors such as fatigue and insulation wear of the cables can cause intermittent connection(IC)faults to occur frequently in the CAN,which will affect the dynamic behavior and the safety of the system.Hence,quantitatively evaluating the performance of the CAN under the influence of IC faults is crucial to real-time health monitoring of the system.In this paper,a novel methodology is proposed for real-time quantitative evaluation of CAN availability when considering IC faults,with the system availability parameter being calculated based on the network state transition model.First,the causal relationship between IC fault and network error response is constructed,based on which the IC fault arrival rate is estimated.Second,the states of the network considering IC faults are analyzed,and the deterministic and stochastic Petri net(DSPN)model is applied to describe the transition relationship of the states.Then,the parameters of the DSPN model are determined and the availability of the system is calculated based on the probability distribution and physical meaning of markings in the DSPN model.A testbed is constructed and case studies are conducted to verify the proposed methodology under various experimental setups.Experimental results show that the estimation results obtained using the proposed method agree well with the actual values.展开更多
Controller area networks （CANs） have been designed for multiplexing communication between electronic control units （ECUs） in vehicles and many high-level industrial control applications. When a CAN bus is overload...Controller area networks （CANs） have been designed for multiplexing communication between electronic control units （ECUs） in vehicles and many high-level industrial control applications. When a CAN bus is overloaded by a large number of ECUs connected to it, both the waiting time and the error probability of the data transmission are increased. Thus, it is desirable to reduce the CAN frame length, since the duration of data transmission is proportional to the frame length. In this paper, we present a CAN message compression method to reduce the CAN frame length. Experimental results indicate that CAN transmission data can be compressed by up to 81.06% with the proposed method. By using an embedded test board, we show that 64-bit engine management system （EMS） CAN data compression can be performed within 0.16 ms; consequently, the proposed algorithm can be successfully used in automobile applications.展开更多
To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dyn...To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dynamically determining the transcoder＇s objective bit rate, according to the bandwidth variation of the wireless channel and the buffer occupancy. Then the transient performance, steady performance, and computational complexity of the algorithm are analyzed. Finally, the experiment results demonstrate that the algorithm can improve the synthetic performance of rate control through the compromise between the end-to-end delay and the playout quality.展开更多
The extreme operational environmental conditions and aging conditions of subsea structures pose a risk to their structural integrity and is critical to their safety.Nondestructive testing is essential to identify defe...The extreme operational environmental conditions and aging conditions of subsea structures pose a risk to their structural integrity and is critical to their safety.Nondestructive testing is essential to identify defects developing within the structure,allowing repair in a timely manner to mitigate against failures that cause damage to the environment and pose a hazard to human operators.However,to be cost effective,inspections must be carried out without taking the risers out of service.This poses significant safety risks if undertaken manually.This paper presents the development of an automated inspection system for flexible risers that are used to connect wellheads on the seafloor to the offshore production and storage facility.Due to the complex structure of risers,radiography is considered as the best technique to inspect multiple layers of the risers.However,radiography inspection,in turn,requires a robotic system for in-situ inspection with higher payload capacity,precise movement of source and detector which is able to withstand an extreme operational environment.The deployment of a radiography inspection system hasbeen achieved bydeveloping acustomized subsearobotic system called RiserSure that can provide precise scanning motion of a gamma ray source and digital detector moving in alignment.The prototype has been tested on a flexible riser during shallow water sea trials with the system placed around a riser by a remotely operated vehicle.The results from the trials show that the internal inner and outer tensile armor layer and defects in the riser can be successfully imaged in real operational conditions.展开更多
为满足智能船舶数据采集系统的多通信协议传输需求,确保数据传输的实时性、可靠性和稳定性,在采用嵌入式操作系统Linux的工控机上设计一种支持多通信模式的船舶数据采集系统。该系统包含数据传输、数据解析和数据存储等3个模块,其中:数...为满足智能船舶数据采集系统的多通信协议传输需求,确保数据传输的实时性、可靠性和稳定性,在采用嵌入式操作系统Linux的工控机上设计一种支持多通信模式的船舶数据采集系统。该系统包含数据传输、数据解析和数据存储等3个模块,其中:数据传输模块采用CAN(Controller Area Network)协议、TCP/IP(Transmission Control Protocol/Internet Protocol)协议和串口RS232协议实现;数据解析模块用于对数据进行格式转换,以TCP/IP协议的形式将其发送给上位机,并在上位机中利用MATLAB软件对其进行解析。以北斗导航接收机为数据源对该系统的有效性进行试验验证,结果表明,基于Linux的多通信模式数据采集系统能满足智能船舶多样化传感器接口,以及数据可靠、准确、实时传输和处理的需求。展开更多
基于嵌入式实时操作系统FreeRTOS和可变速率控制器局域网(Controller Area Network with Flexible Data Rate,CAN FD),设计并实现了基于统一诊断服务(Unified Diagnostic Services,UDS)协议的车辆诊断系统,包括微控制器程序、上位机测...基于嵌入式实时操作系统FreeRTOS和可变速率控制器局域网(Controller Area Network with Flexible Data Rate,CAN FD),设计并实现了基于统一诊断服务(Unified Diagnostic Services,UDS)协议的车辆诊断系统,包括微控制器程序、上位机测试程序和连接二者的支持CAN FD功能的USB/CAN转换器。微控制器程序设计使用嵌入式操作系统FreeRTOS建立软件框架,开发了传输层任务、应用层任务和CAN中断服务程序。上位机测试程序针对数据读写和在线编程功能进行重点测试。结果表明,该文使用的设计方案能满足ISO 14229-1-2020规范中要求的响应时间要求,同时具有可靠、易于维护等优势。展开更多
随着传感、信号处理和通信技术的快速发展,关于网络控制系统(Networked control systems,NCSs)的研究引起了极大的关注.本文拟回顾关于网络控制系统的最新研究进展.为揭示反馈通信网络对控制系统的影响,主要讨论了为满足不同控制目的所...随着传感、信号处理和通信技术的快速发展,关于网络控制系统(Networked control systems,NCSs)的研究引起了极大的关注.本文拟回顾关于网络控制系统的最新研究进展.为揭示反馈通信网络对控制系统的影响,主要讨论了为满足不同控制目的所需的各种网络条件,例如:在时变信道的环境下,保证线性系统可镇定性所需的最低编码率;在间断观测的环境下,保证卡尔曼滤波器稳定性的临界丢包条件;在时不变连接图的环境下,达到线性多自主体系统趋同性所需的网络拓扑结构;在通信资源有限的情况下,基于事件驱动的采样与控制方法等.展开更多
为满足汽车进一步智能化的需要,同时支持时间触发与事件触发服务兼具设计与调度灵活性成为汽车总线发展的方向,针对当前现有车上控制器局域网络(Controller area network,CAN)总线不能有效处理时间触发的周期性信息,时间触发的控制器局...为满足汽车进一步智能化的需要,同时支持时间触发与事件触发服务兼具设计与调度灵活性成为汽车总线发展的方向,针对当前现有车上控制器局域网络(Controller area network,CAN)总线不能有效处理时间触发的周期性信息,时间触发的控制器局域网络(Time-triggered CAN,TTCAN)协议具有时间触发功能但缺乏信息调度的灵活性等问题,分析基于动态规划的柔性时间触发控制器局域网络(Flexible time-triggered CAN,FTTCAN),研究FTTCAN双相基本周期结构。分别推导出双相内基于动态规划调度的信息传输时间特性参数分析方法,并基于FTTCAN原理具体设计出纯电动汽车FTTCAN总线控制系统。采用动态规划方法设计出信息调度策略,对信息传输特性进行分析及与CAN方案对比。最后在CAN总线开发系统上进行FTTCAN协议运行试验。对比与试验结果验证了采用FTTCAN的方案兼具时间触发与事件触发服务功能,且具有较好灵活性特点,是汽车总线系统优化设计的好方法。展开更多
作为一种新的电子医疗技术,无线体域网(wireless body area networks,WBANs)将在病情监测中发挥重要作用,安全性及隐私性保护是无线体域网的重要内容。针对WBANs数据访问控制提出一种细粒度的数据访问方法,该方法采用基于属性的数据加...作为一种新的电子医疗技术,无线体域网(wireless body area networks,WBANs)将在病情监测中发挥重要作用,安全性及隐私性保护是无线体域网的重要内容。针对WBANs数据访问控制提出一种细粒度的数据访问方法,该方法采用基于属性的数据加密方法,加密者将数据访问结构作为访问策略,当解密者所具有的属性满足该结构时,即可访问该数据,否则,拒绝用户访问。分别从正确性、安全性及能量消耗三方面对方案进行分析。仿真实验结果表明,本方案相对其他方案能量消耗较小。展开更多
基金supported by the Natural Science Foundation of Shanghai (Grant No.06ZR14131)the Key Lab Project of Shanghai(Grant No.08DZ2272400)the Excellent Discipline Head Plan Project of Shanghai (Grant No.08XD14018)
文摘In networked control system (NCS) where control loop is closed over communication network, limited data rate may deteriorate control performance even destabilize the control system. In this paper, performance analysis of a typical second-order control system with data rate constraints is conducted, and the concept of critical data rate (CDR) is presented. In order to find the CDR in NCS, an approximate searching method is proposed to guarantee acceptable control performance.
文摘为了提高控制器局域网络(controller area network,CAN)通信的实时性,文章基于时间触发CAN(time-triggered CAN,TTCAN)协议,采用verilog硬件描述语言设计实现TTCAN总线控制器。该控制器可在经典CAN模式与TTCAN模式之间进行切换,同时兼容可变速率CAN(CAN with flexible data rate,CAN FD)协议下的高速通信。实验结果证明,相较于经典CAN总线控制器,该TTCAN总线控制器能够减少在高总线负载率下周期性报文的发送延时,在全波特率范围内且总线负载率大于等于60%的情况下,能够减少75%以上的CAN报文发送延时。
基金supported by the National Natural Science Foundation of China(No.52072341)。
文摘Controller area networks(CANs),as one of the widely used fieldbuses in the industry,have been extended to the automation field with strict standards for safety and reliability.In practice,factors such as fatigue and insulation wear of the cables can cause intermittent connection(IC)faults to occur frequently in the CAN,which will affect the dynamic behavior and the safety of the system.Hence,quantitatively evaluating the performance of the CAN under the influence of IC faults is crucial to real-time health monitoring of the system.In this paper,a novel methodology is proposed for real-time quantitative evaluation of CAN availability when considering IC faults,with the system availability parameter being calculated based on the network state transition model.First,the causal relationship between IC fault and network error response is constructed,based on which the IC fault arrival rate is estimated.Second,the states of the network considering IC faults are analyzed,and the deterministic and stochastic Petri net(DSPN)model is applied to describe the transition relationship of the states.Then,the parameters of the DSPN model are determined and the availability of the system is calculated based on the probability distribution and physical meaning of markings in the DSPN model.A testbed is constructed and case studies are conducted to verify the proposed methodology under various experimental setups.Experimental results show that the estimation results obtained using the proposed method agree well with the actual values.
基金Project supported by the Information Technology R&D Program of MOTIE/KEIT(No.10044092)Research Funds of Chonbuk National University in 2013
文摘Controller area networks （CANs） have been designed for multiplexing communication between electronic control units （ECUs） in vehicles and many high-level industrial control applications. When a CAN bus is overloaded by a large number of ECUs connected to it, both the waiting time and the error probability of the data transmission are increased. Thus, it is desirable to reduce the CAN frame length, since the duration of data transmission is proportional to the frame length. In this paper, we present a CAN message compression method to reduce the CAN frame length. Experimental results indicate that CAN transmission data can be compressed by up to 81.06% with the proposed method. By using an embedded test board, we show that 64-bit engine management system （EMS） CAN data compression can be performed within 0.16 ms; consequently, the proposed algorithm can be successfully used in automobile applications.
基金the National High Technology Research and Development Program (2007AA1Z24002003AA1Z2210).
文摘To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dynamically determining the transcoder＇s objective bit rate, according to the bandwidth variation of the wireless channel and the buffer occupancy. Then the transient performance, steady performance, and computational complexity of the algorithm are analyzed. Finally, the experiment results demonstrate that the algorithm can improve the synthetic performance of rate control through the compromise between the end-to-end delay and the playout quality.
基金The authors acknowledge the support and funding provided by the European Union’s Horizon 2020 FTIPilot-2016-1 Fast Track to Innovation program under grant agreement No 730753 for the RiserSure project(Website:www.risersure.eu).
文摘The extreme operational environmental conditions and aging conditions of subsea structures pose a risk to their structural integrity and is critical to their safety.Nondestructive testing is essential to identify defects developing within the structure,allowing repair in a timely manner to mitigate against failures that cause damage to the environment and pose a hazard to human operators.However,to be cost effective,inspections must be carried out without taking the risers out of service.This poses significant safety risks if undertaken manually.This paper presents the development of an automated inspection system for flexible risers that are used to connect wellheads on the seafloor to the offshore production and storage facility.Due to the complex structure of risers,radiography is considered as the best technique to inspect multiple layers of the risers.However,radiography inspection,in turn,requires a robotic system for in-situ inspection with higher payload capacity,precise movement of source and detector which is able to withstand an extreme operational environment.The deployment of a radiography inspection system hasbeen achieved bydeveloping acustomized subsearobotic system called RiserSure that can provide precise scanning motion of a gamma ray source and digital detector moving in alignment.The prototype has been tested on a flexible riser during shallow water sea trials with the system placed around a riser by a remotely operated vehicle.The results from the trials show that the internal inner and outer tensile armor layer and defects in the riser can be successfully imaged in real operational conditions.
文摘为满足智能船舶数据采集系统的多通信协议传输需求,确保数据传输的实时性、可靠性和稳定性,在采用嵌入式操作系统Linux的工控机上设计一种支持多通信模式的船舶数据采集系统。该系统包含数据传输、数据解析和数据存储等3个模块,其中:数据传输模块采用CAN(Controller Area Network)协议、TCP/IP(Transmission Control Protocol/Internet Protocol)协议和串口RS232协议实现;数据解析模块用于对数据进行格式转换,以TCP/IP协议的形式将其发送给上位机,并在上位机中利用MATLAB软件对其进行解析。以北斗导航接收机为数据源对该系统的有效性进行试验验证,结果表明,基于Linux的多通信模式数据采集系统能满足智能船舶多样化传感器接口,以及数据可靠、准确、实时传输和处理的需求。
文摘基于嵌入式实时操作系统FreeRTOS和可变速率控制器局域网(Controller Area Network with Flexible Data Rate,CAN FD),设计并实现了基于统一诊断服务(Unified Diagnostic Services,UDS)协议的车辆诊断系统,包括微控制器程序、上位机测试程序和连接二者的支持CAN FD功能的USB/CAN转换器。微控制器程序设计使用嵌入式操作系统FreeRTOS建立软件框架,开发了传输层任务、应用层任务和CAN中断服务程序。上位机测试程序针对数据读写和在线编程功能进行重点测试。结果表明,该文使用的设计方案能满足ISO 14229-1-2020规范中要求的响应时间要求,同时具有可靠、易于维护等优势。
文摘随着传感、信号处理和通信技术的快速发展,关于网络控制系统(Networked control systems,NCSs)的研究引起了极大的关注.本文拟回顾关于网络控制系统的最新研究进展.为揭示反馈通信网络对控制系统的影响,主要讨论了为满足不同控制目的所需的各种网络条件,例如:在时变信道的环境下,保证线性系统可镇定性所需的最低编码率;在间断观测的环境下,保证卡尔曼滤波器稳定性的临界丢包条件;在时不变连接图的环境下,达到线性多自主体系统趋同性所需的网络拓扑结构;在通信资源有限的情况下,基于事件驱动的采样与控制方法等.
文摘作为一种新的电子医疗技术,无线体域网(wireless body area networks,WBANs)将在病情监测中发挥重要作用,安全性及隐私性保护是无线体域网的重要内容。针对WBANs数据访问控制提出一种细粒度的数据访问方法,该方法采用基于属性的数据加密方法,加密者将数据访问结构作为访问策略,当解密者所具有的属性满足该结构时,即可访问该数据,否则,拒绝用户访问。分别从正确性、安全性及能量消耗三方面对方案进行分析。仿真实验结果表明,本方案相对其他方案能量消耗较小。
