Quasi-real time inversion method of three-dimensional epicenter coordinate, trigger time, and magnitude based on CORS

This study explores the quasi-real time inversion principle and precision estimation of three-dimensional coordinates of the epicenter, trigger time and magnitude of earthquakes with the aim to improve traditional methods, which are flawed due to missing information or distortion in the seismograph records. The epicenter, trigger time and magnitude from the Lushan earthquake are inverted and analyzed based on high-frequency GNSS data. The inversion results achieved a high precision, which are consistent with the data published by the China Earthquake Administration. Moreover, it has been proven that the inversion method has good theoretical value and excellent application prospects.

Communication Resource Planning Algorithm Based on Time Triggered DIMA Architecture

Traditional scheduling algorithms for avionics communication have the shortcoming of messages accumulation,the efficiency and reliability of the service can be improved by combining the distributed integrated modular avionics(DIMA)system with a time trigger mechanism.To further improve the utilization of system resources,the static scheduling algorithm of time triggered service is studied.By making the time trigger message schedule dispersedly,the stabilities of both the available time slots for the event triggered messages and the system will be improved.An improved two-dimensional bin packing algorithm is also presented to achieve the above-mentioned purpose with an extra benefit of better delay performance.

Hybrid-triggered consensus for multi-agent systems with time-delays,uncertain switching topologies, and stochastic cyber-attacks

We propose a new approach to discuss the consensus problem of multi-agent systems with time-varying delayed control inputs, switching topologies, and stochastic cyber-attacks under hybrid-triggered mechanism.A Bernoulli variable is used to describe the hybrid-triggered scheme, which is introduced to alleviate the burden of the network.The mathematical model of the closed-loop control system is established by taking the influences of time-varying delayed control inputs,switching topologies, and stochastic cyber-attacks into account under the hybrid-triggered scheme.A theorem as the main result is given to make the system consistent based on the theory of Lyapunov stability and linear matrix inequality.Markov jumps with uncertain rates of transitions are applied to describe the switch of topologies.Finally, a simulation example demonstrates the feasibility of the theory in this paper.

Employing Two ‘Sandwich Delay’ Mechanisms to Enhance Predictability of Embedded Systems Which Use Time-Triggered Co-Operative Architectures

In many real-time resource-constrained embedded systems, highly-predictable system behavior is a key design requirement. The “time-triggered co-operative” (TTC) scheduling algorithm provides a good match for a wide range of low-cost embedded applications. As a consequence of the resource, timing, and power constraints, the implementation of such algorithm is often far from trivial. Thus, basic implementation of TTC algorithm can result in excessive levels of task jitter which may jeopardize the predictability of many time-critical applications using this algorithm. This paper discusses the main sources of jitter in earlier TTC implementations and develops two alternative implementations – based on the employment of “sandwich delay” (SD) mechanisms – to reduce task jitter in TTC system significantly. In addition to jitter levels at task release times, we also assess the CPU, memory and power requirements involved in practical implementations of the proposed schedulers. The paper concludes that the TTC scheduler implementation using “multiple timer interrupt” (MTI) technique achieves better performance in terms of timing behavior and resource utilization as opposed to the other implementation which is based on a simple SD mechanism. Use of MTI technique is also found to provide a simple solution to “task overrun” problem which may degrade the performance of many TTC systems.

Event-Triggered Zero-Gradient-Sum Distributed Algorithm for Convex Optimization with Time-Varying Communication Delays and Switching Directed Topologies

Nowadays, distributed optimization algorithms are widely used in various complex networks. In order to expand the theory of distributed optimization algorithms in the direction of directed graph, the distributed convex optimization problem with time-varying delays and switching topologies in the case of directed graph topology is studied. The event-triggered communication mechanism is adopted, that is, the communication between agents is determined by the trigger conditions, and the information exchange is carried out only when the conditions are met. Compared with continuous communication, this greatly saves network resources and reduces communication cost. Using Lyapunov-Krasovskii function method and inequality analysis, a new sufficient condition is proposed to ensure that the agent state finally reaches the optimal state. The upper bound of the maximum allowable delay is given. In addition, Zeno behavior will be proved not to exist during the operation of the algorithm. Finally, a simulation example is given to illustrate the correctness of the results in this paper.

Event-Triggered Finite-Time <i>H</i>_∞Control for Switched Stochastic Systems

This paper investigates the problem of event-triggered finite-time H∞ control for a class of switched stochastic systems. The main objective of this study is to design an event-triggered state feedback H∞ controller such that the resulting closed-loop system is finite-time bounded and satisfies a prescribed H∞ level in some given finite-time interval. Based on stochastic differential equations theory and average dwell time approach, sufficient conditions are derived to ensure the finite-time stochastic stability with the prescribed H∞ performance for the relevant closed-loop system by employing the linear matrix inequality technique. Finally, the desired state feedback H∞ controller gain matrices can be expressed in an explicit form.

Event-Triggered Finite-Time H∞ Filtering for Discrete-Time Nonlinear Stochastic Systems

This paper addresses the problem of event-triggered finite-time H∞ filter design for a class of discrete-time nonlinear stochastic systems with exogenous disturbances. The stochastic Lyapunov-Krasoviskii functional method is adopted to design a filter such that the filtering error system is stochastic finite-time stable (SFTS) and preserves a prescribed performance level according to the pre-defined event-triggered criteria. Based on stochastic differential equations theory, some sufficient conditions for the existence of H∞ filter are obtained for the suggested system by employing linear matrix inequality technique. Finally, the desired H∞ filter gain matrices can be expressed in an explicit form.

Time-varying formation for general linear multi-agent systems via distributed event-triggered control under switching topologies

This paper investigates the time-varying formation problem for general linear multi-agent systems using distributed event-triggered control strategy.Different from the previous works,to achieve the desired time-varying formation,a distributed control scheme is designed in an event-triggered way,in which for each agent the controller is triggered only at its own event times.The interaction topology among agents is assumed to be switching.The common Lyapunov function as well as Riccati inequality is applied to solve the time-varying formation problem.Moreover,the Zeno behavior of triggering time sequences can be excluded for each agent.Finally,a simulation example is presented to illustrate the effectiveness of the theoretical results.

基于OSEKTime的共存模型的改进与实现

OSEKTime规范提出了基于时间触发操作系统与基于OSEK/VDX标准实现的操作系统的共存模型。在分析OSEKTime规范的基础上,针对该规范的消息触发任务存在着非实时性问题,提出并实现了一种合理的、能与OS-EK OS共存的实时时间触发操作系统,确保了时间触发任务的实时性和对消息触发任务的死限时间内的及时处理。

Event-Triggered Sliding Mode Control for Trajectory Tracking of Nonlinear Systems

In this paper, an event-triggered sliding mode control approach for trajectory tracking problem of nonlinear input affine system with disturbance has been proposed. A second order robotic manipulator system has been modeled into a general nonlinear input affine system. Initially, the global asymptotic stability is ensured with conventional periodic sampling approach for reference trajectory tracking. Then the proposed approach of event-triggered sliding mode control is discussed which guarantees semi-global uniform ultimate boundedness. The proposed control approach guarantees non-accumulation of control updates ensuring lower bounds on inter-event triggering instants avoiding Zeno behavior in presence of the disturbance. The system shows better performance in terms of reduced control updates, ensures system stability which further guarantees optimization of resource usage and cost. The simulation results are provided for validation of proposed methodology for tracking problem by a robotic manipulator. The number of aperiodic control updates is found to be approximately 44% and 61% in the presence of constant and time-varying disturbances respectively.

An Active Triggered Surge Protective Gap

A triggered surge protective device is designed and its discharge characteristics axe studied. The experimental results show that the triggered surge protective device has excellent surge protective characteristics. When the gap distance is 5 mm, p. d is 90 Pa.mm and without an active energy trigger circuit, the DC breakdown voltage of the triggered surge protective device is 2.32 kV and the pulse breakdown voltage is 5.75 kV. Therefore, the pulse voltage ratio, which is defined as the specific value of pulse breakdown voltage and DC breakdown voltage, is 2.48. With a semiconductor ZnO flashover trigger device and an active energy coupling trigger circuit, the pulse breakdown voltage can be reduced to 3.32 kV, the pulse voltage ratio is 1.43 and the response time is less than 100 ns. These results are helpful in laying a theoretical foundation for further studies on triggered surge protective devices.

Analytical investigation of the boundary-triggered phase transition dynamics in a cellular automata model with a slow-to-start rule

Previous studies suggest that there are three different jam phases in the cellular automata automaton model with a slow-to-start rule under open boundaries.In the present paper,the dynamics of each free-flow-jam phase transition is studied.By analysing the microscopic behaviour of the traffic flow,we obtain analytical results on the phase transition dynamics.Our results can describe the detailed time evolution of the system during phase transition,while they provide good approximation for the numerical simulation data.These findings can perfectly explain the microscopic mechanism and details of the boundary-triggered phase transition dynamics.

Experimental Study on Triggering Characteristics of a Surface Flashover Triggered Vacuum Switch

Triggering characteristics of triggered vacuum switch （TVS）, including the discharge delay time, delay jitter, range of operational voltage and peak of pulsed current, are investigated. Both structure and experimental circuit of TVS are presented. The results indicate that TVS, as a surface flashover triggering device with high dielectric permittivity material, is with excellent triggering characteristics. When the hold-off voltage reaches 120 kV, the minimum operational voltage is 1.3 kV, and the minimum discharge delay time and jitter are 100 ns and ±10 ns, respectively. The peak current is up to 240 kA when the operational voltage reaches 100 kV. TVS can well satisfy the main demands of high voltage and current applications, and can also be used under a multi-crowbar circuit.

考虑时延的异质协作车队事件触发控制研究

针对目前研究较少考虑车辆混行造成的异质问题与时延问题,本文提出了一种具有时延的异质协作式自动驾驶车队事件触发控制方法 .首先,建立了考虑混行的异质车辆时延模型;其次,基于PID(proportional-integral-derivative)控制与模型预测控制(MPC),设计了不同模式下的事件触发控制器;然后,在城市和紧急情况下,对所提出的控制器进行了仿真分析;最后,基于Jetson Nano模型车进行了实车实验.仿真与实验结果表明,所提出的事件触发控制方法能够在不同情况下更好地权衡控制精度与计算速度间的矛盾.在带有通信时延的紧急情况下,仍能够保持较低的误差.

基于事件触发的预设时间航天器轨迹跟踪控制

针对通信受限条件下的航天器轨迹跟踪问题,提出了一种基于事件触发的预设时间控制算法。为了满足不同任务场景下对航天器快速性的要求,本文设计了一种预设时间轨迹跟踪控制算法。结合反步控制理论及预设时间动态增益,最终实现轨迹跟踪系统的预设时间收敛。作为一种典型的网络化控制系统,航天器在执行任务过程中可能会受到自身通信能力的限制,造成通信阻塞、时延和丢包等问题。为此,本文提出了一种基于动态参数的事件触发算法,在保证系统控制精度的同时,一定程度上避免了控制中心与航天器本体间不必要的通信资源消耗。相比于传统的静态事件触发算法,文中基于动态参数的事件触发算法在减少通信频率方面更具优势。通过理论分析和仿真实验验证所提控制算法的有效性。

基于面向TTE的新型数据综合系统的设计与实现

针对传统总线无法实时网络传输,新型总线时间触发以太网(TTE)兼容IP协议和IEEE802.3协议,但TT业务和BE业务需设备满足TTE协议,实际工程缺少适用性的问题,设计了一种基于FPGA的时间触发以太网数据综合系统。该数据综合系统以FPGA作为核心控制器,千兆网作为主要通信接口,在满足高速率、高宽带、高灵活的前提下,设计出数据综合模块,将多种传统总线与TTE总线良好兼容。试验结果表明:系统在同步精度高达40 ns、通信抖动仅为392 ns的前提下,数据转换收发无误码现象。同时将多种数据混合编帧,具备极高的稳定性与灵活性,为TTE网络数据服务于实际工程提供了可靠的解决方案。

拦截机动目标的固定时间事件触发协同制导律

针对无向通信拓扑结构下的多枚导弹考虑角度约束同时攻击机动目标的问题,提出一种事件触发控制下的固定时间收敛分布式多弹协同制导律.首先,建立导弹-目标相对运动学模型,在视线坐标系下解耦为沿视线和垂直视线两个方向.其次,在视线切向考虑时间约束,提出一种基于事件触发机制的固定时间收敛协同制导律,保证攻击时间的一致性;在视线法向上考虑空间角度约束,提出一种基于固定时间收敛理论的分布式空间协同制导律,使视线角和视线角速率快速收敛到期望值,以满足脱靶量和终端角度约束;同时,针对目标机动引起的系统扰动,采用固定时间收敛的观测器进行在线估计与补偿.利用Lyapunov理论,证明了所提出协同制导律的稳定性.最后,通过数学仿真,验证了所提出的协同制导律的有效性.

基于事件触发的高阶切换非线性系统的有限时间动态面跟踪控制

针对一类高阶切换非线性系统,研究了基于事件触发的自适应跟踪控制问题.首先,利用模糊逻辑系统近似系统中的不确定非线性函数.通过引入有限时间收敛的一阶滤波器,解决了由虚拟控制器重复求导所导致的计算复杂度问题.利用backstepping控制技术和公共李雅普诺夫函数方法,提出了一种自适应模糊有限时间动态面控制算法.所提出的控制方案可以保证闭环系统的所有信号在有限时间内实现有界并且跟踪误差在有限时间内收敛到原点的一个小邻域内.最后,数值例子说明了所提出控制策略的有效性.

自适应事件触发机制下分布时滞Markov跳变网络化系统H_(∞)故障检测

传统事件触发机制中阈值的选择会对信号传输效率产生很大影响。针对此问题,研究了自适应事件触发机制下具有分布时滞的Markov网络化系统的故障检测问题。设计了一种模态相关的自适应事件触发机制,通过动态调整阈值,提高了网络资源利用率。考虑网络时延和数据丢包现象,同步设计触发器和故障检测滤波器。构造模态相关的Lyapunov泛数,根据积分不等式技术推导出使系统随机稳定且具有H_(∞)性能的充分条件。利用解耦方法和LMI技术求解出了故障检测滤波器参数。最后通过数值仿真验证了方案在节省网络资源上的优势。

面向载人月球探测的确定性以太网应用研究

确定性以太网(时间触发以太网和时间敏感网络)是在传统以太网上增加时间同步、时间感知整形等机制,能够提供高可靠低时延的确定性通信服务的技术。确定性以太网在航天器中的应用,可以解决现有总线难以满足未来空间系统架构开放性、数据处理实时性和数据传输可靠性等应用需求的问题。对确定性以太网技术产生的背景、技术原理和发展现状进行分析,提出一种“先融合后增强”的推进步骤,即由时间触发以太网和时间敏感网络融合的架构逐步过渡到完整的时间敏感网络架构,为我国未来航天器信息系统数据总线的设计和实现提供思路。