Optimal control of continuous-time linear systems with a time-varying, random delay

We study a finite horizon optimal control problem for a class of linear systems with a randomly varying time-delay. The systems of this type may arise in embedded control applications and in certain applications in economics. The delay value is treated as an unknown variable but with known statistical properties, modelled by a Markov process with a finite number of states. The “probabilistic delay averaging” approach is employed to determine the optimal control in the form which is independent of the delay value.     

Optimal stabilization of constant power loads with input LC-filters

This contribution examines fundamental performance limitations of active stabilization of constant power loads with input LC filters. In terms of the load input admittance, stabilization is posed as a linear H_∞ optimization problem, where the influence of stabilization on power control performance is minimized while meeting stability and robustness constraints. It is shown that the bandwidth of power control is upper limited by the resonance frequency of the input filter and that additional feedforward controllers can be used to individually shape reference tracking and disturbance rejection. Optimal results are verified through simulations using two different stabilization schemes.     

Optimal reactive power dispatch with uncertainties in load demand and renewable energy sources adopting scenario-based approach

Optimizing reactive power flow in electrical network is an important aspect of system study as the reactive power supports network voltage which needs to be maintained within desirable limits for system reliability. A network consisting of only conventional thermal generators has been extensively studied for optimal active and reactive power dispatch. However, increasing penetration of renewable sources into the grid necessitates power flow studies incorporating these sources. This paper presents a formulation and solution procedure for stochastic optimal reactive power dispatch (ORPD) problem with uncertainties in load demand, wind and solar power. Appropriate probability density functions (PDFs) are considered to model the stochastic load demand and the power generated from the renewable energy sources. Numerous scenarios are created running Monte-Carlo simulation and scenario reduction technique is implemented to deal with reduced number of scenarios. Real power loss and steady state voltage deviation of load buses in the network are set as the objectives of optimization. Success history based adaptive differential evolution (SHADE) is adopted as the basic search algorithm. SHADE has been successfully integrated with a constraint handling technique, called epsilon constraint (EC) handling, to handle constraints in ORPD problem. The effectiveness of a proper constraint handling technique is substantiated with case studies for deterministic ORPD on base configurations of IEEE 30-bus and 57-bus systems using SHADE-EC algorithm. The single-objective and multi-objective stochastic ORPD cases are also solved using the SHADE-EC algorithm. The results are discussed, compared and critically analyzed in this study.     

实现无线传输能量效率最大化的功率控制新方法

能量效率是无线自组织网络中非常重要的性能指标。到目前为止,自组织网络的能量效率还没有一个普遍接受的定义,且得出的结论多数是渐近的或定性的,其实用性非常有限。将比特看作质量为1的物理粒子,假设其在传输过程中携带了一定的信息动能,并将能量效率定义为物理能量转化为信息能量的比率,然后从信息论的角度定量地研究了无线传输的能量效率。通过理论分析,得出如下结论：能量效率随发送功率的增加非单调变化,且存在一个最优发送功率,使得能量效率取得最大值;给出了相应的最优发送功率,这将为协议设计提供最直接的帮助。根据得出的理论结果,提出了一种基于参数估计的功率控制的方法,并在Micaz传感器节点上进行了相关的实验。实验结果证明了此功率控制方法的有效性。     

认知中继选择系统发射功率受限时的性能研究

基于译码转发协议,对一个双跳认知中继选择系统的中断性能进行了研究.该系统采用半双工的通信模式,所有节点均配置单个天线,次级系统同时受到来自于主接收用户最大干扰功率和最大传输功率的双重限制.在独立非同一分布的瑞利信道环境下,推导出了中断概率的准确闭合表达式和高传输功率时的渐进闭合表达式,并利用蒙特卡罗仿真实验对理论分析结果的正确性进行了验证.实验结果表明:中继个数的增加降低了中断概率,提升了系统的性能,但是提升空间有限.另外,最大干扰门限和最大传输功率的变化关系给系统性能的提升带来瓶颈.     

Optimal control problems with multiple characteristic time points in the objective and constraints

In this paper, we develop a computational method for a class of optimal control problems where the objective and constraint functionals depend on two or more discrete time points. These time points can be either fixed or variable. Using the control parametrization technique and a time scaling transformation, this type of optimal control problem is approximated by a sequence of approximate optimal parameter selection problems. Each of these approximate problems can be viewed as a finite dimensional optimization problem. New gradient formulae for the cost and constraint functions are derived. With these gradient formulae, standard gradient-based optimization methods can be applied to solve each approximate optimal parameter selection problem. For illustration, two numerical examples are solved.     

Stabilization in probability and mean square of controlled stochastic dynamical system with state delay

Although stochastic dynamical systems have received a great deal of attention in terms of stabilization studies, so far there are few works on controlled stochastic dynamical systems with state delay. In this paper, a controlled stochastic dynamical system represented by a stochastic differential equation with state delay is considered. Condition under which the system is exponentially stable in mean square and in probability is examined.     

Optimal D2D power for secure D2D communication with random eavesdropper in 5G-IoT networks

In the rapidly evolving landscape of fifth generation Internet of Things (5G-IoT) networks, Device-to-Device (D2D) communication has emerged as a promising paradigm to enhance secrecy transmission rate (STR) and connectivity. However, the security of D2D communications in the presence of eavesdroppers remains a critical challenge. This article investigates the problem of optimizing D2D transmit power to achieve secure D2D communication while considering the presence of random eavesdroppers in 5G-IoT networks. We propose a novel secrecy-based power control approach (SRMWPCA) approach to model the random distribution of eavesdroppers in the network, taking into account their varying distances from D2D pairs and deliberately increasing interference at the eavesdropper's link. By leveraging tools from stochastic geometry, we derive an analytical expression for the secrecy transmission probability (STP), which quantifies the probability of eavesdroppers successfully decoding the D2D transmission. In this analysis, we have incorporated practical considerations such as channel fading, path loss, and interference from other devices. To enhance the security of D2D communication, we formulate an optimization problem to determine the optimal transmit power levels for D2D pairs, subject to constraints on the secrecy transmission probability and interference to the cellular network. We propose an efficient algorithm to find the power allocation that maximizes the secrecy outage performance while meeting these constraints. Simulation results demonstrate the effectiveness of the proposed approach in achieving secure D2D communication in 5G-IoT networks with random eavesdroppers. The performance of the proposed SRMWPCA approach improved by 23.25% and 20.9% compared with standard approaches in terms of the secrecy rate and throughput of the users from malicious attacks.     

一种软启停正负双直流电源的设计

变形镜驱动器正负电源加电或者断电不同步,导致其在加电瞬间或者断电瞬间,输出端会输出一个-38.0V和86.0V的冲击电压,这个冲击电压使得变形镜在未开始工作时就产生了较为严重的面形畸变,为此研制了基于微处理器的软启停直流电源,它输出两路按一定时序变化的输出电压作为后续两个继电器的控制端,再通过这两个继电器分别控制变形镜驱动器正、负电源的导断,从而使得变形镜驱动器的正负电源同时加载或者卸载。在硬件平台了进行了实验验证,结果表明,使用软启停直流电源后,变形镜驱动器加电瞬间或断电瞬间,其产生的脉冲电压的峰-峰不超过0.45V,远远小于未使用软启停直流电源前的冲击电压,满足了系统的设计要求。     

约束条件下的巡线机器人逆运动学求解

高压输电线路巡检机器人是一种多关节悬挂运动机构,要实现其运动控制就需要根据机器人的本身机构特点和悬挂系统的运动约束条件进行运动学分析.本文利用微分扭转法对巡线机器人的正向运动学进行了求解,并通过对机器人悬挂系统的力学分析,得到了机器人运动学的约束条件,并在这种约束条件下,采用了一种可用来进行实时控制的迭代循环坐标下降(CCD)算法,来进行机器人的逆运动学求解.这种迭代算法对于有运动约束系统的逆运动学求解具有较强的适用性,而且它具有较好的收敛性和有效性,适合于在线计算,便于巡线机器人的实时运动控制.     

Optimal Deployment of Mobile Sensors for Target Tracking in 2D and 3D Spaces

This paper proposes a control strategy to autonomously deploy optimal placements of range-only mobile sensors in 2D and 3D spaces. Based on artificial potential approaches, the control strategy is designed to minimize the intersensor and external potentials. The inter-sensor potential is the objective function for optimal sensor placements. A placement is optimal when the inter-sensor potential is minimized. The external potential is introduced to fulfill constraints on sensor trajectories. Since artificial potential approaches can handle various issues such as obstacle avoidance and collision avoidance among sensors, the proposed control strategy provides a flexible solution to practical autonomous optimal sensor deployment. The control strategy is applied to several optimal sensor deployment problems in 2D and 3D spaces. Simulation results illustrate how the proposed control strategy can improve target tracking performance.      

移动自组网节能自适应分级功率调控技术研究

针对移动自组网的节能问题,提出基于接收信号强度的链路层分级功率控制方法,通过在通信双方的物理层和链路层添加针对接收数据包的处理功能,应对特定的信道状况和通信状况采用合适的发送功率进行通信,使数据包的接收功率处于合理的范围,并采用睡眠机制应对同步通信之间的干扰,确保实现良好的通信性能。通过NS-2环境下的仿真实验,分析了该功率控制方法在能量节省和网络性能提升上的有效性。     

最小化具有无线携能通信的全双工中继系统发射功率和

考虑在无线网络中采用信息与能量同步传输来提高无线中继系统的性能,提出了基于无线射频网络中采用无线携能通信（SWIPT）技术的具有自能量回收的双向传输全双工中继系统。SWIPT应用在双向全双工中继系统中是一个新的尝试,其中能量受限的目的节点使用从中继和环路信道捕获的能量来发送反馈信息,并给出了全双工中继系统工作的逻辑结构和能量受限的目的节点的物理结构。然后,以最小化系统发射功率和作为优化目标来描述系统的性能,采用功率分配方案进行信息解码和能量捕获,应用半定规划、秩松弛和拉格朗日方法将原始非凸优化方程转化为可解凸优化问题并求解,且联合优化了中继发射功率、发射波束成形向量和功率分配比率。最后,实验仿真对比了所提的新系统与传统双向传输中继系统,结果验证了利用自能量回收不仅可以消除自干扰,而且可以显著优化系统发射功率和,且由于SWIPT技术与全双工中继系统的结合,使得所提出的系统比传统的双向传输系统具有更高的性能增益。     

Optimal dead-time compensator design for stable and integrating processes with time delay

Recently, a modified Smith predictor with a prefilter has been proposed for first-order stable and integrating processes with time delay. The paper is a further investigation on the empirical method. In this paper, an optimal design procedure is developed for the scheme. With respect to the proposed controller and corresponding processes with time delay, the closed-loop time domain responses are estimated quantitatively. The robustness of the closed-loop system is analyzed. Finally, a simple tuning rule is proposed, which allows to tune the controller for desired time domain properties such as overshoot and rise time, or frequency domain criteria such as stability margin and bandwidth.     

Optimal solutions to a class of power management problems in mobile robots

This paper studies an approach to minimize the power consumption of a mobile robot by controlling its traveling speed and the frequency of its on-board processor simultaneously. The problem is formulated as a discrete-time optimal control problem with a random terminal time and probabilistic state constraints. A general solution procedure suitable for arbitrary power functions of the motor and the processor is proposed. Furthermore, for a class of realistic power functions, the optimal solution is derived analytically. Interpretations of the optimal solution in the practical context are also discussed. Simulation results show that the proposed method can save a significant amount of energy compared with some heuristic schemes.     

用于传感网功率控制的并行传输MAC 协议

针对无线传感网（WSNs）中节点间不对称的发射功率引起的隐藏节点和暴露节点问题,提出一种用于传感网功率控制的MAC协议（MAC4PC）.该协议采用邻节点向量表对邻节点的状态及当前会话的信息进行记录,并设计了相关的控制帧收发时序和干扰度判断准则,以保证新建立会话与当前会话互不干涉,从而实现暴露节点的并行传输.仿真结果表明,与802.11 DCF协议、SB-FSMA/CA协议以及GLPCB-PMAC协议相比较,MAC4PC协议提高了网络平均吞吐量,降低了节点平均能耗和数据分组的平均传输时延.     

无线输电技术及其在矿井安全监控系统中的应用

介绍了无线输电技术的概念和发展史,依据现有三大无线电能传输标准,重点阐述了电磁感应式、无线电波式、电磁谐振式3种无线电能传输方式,并认为磁耦合谐振式无线电能传输方式最具研究前景;针对煤矿井下工作环境特点和防爆要求,分析了无线输电技术在矿井中的应用前景,指出矿井安全监控系统是无线输电技术的优先发展领域,并依据《煤矿安全规程》及相关行业标准,通过实例分析了矿井安全监控系统应用无线输电技术的需求和意义;指出了矿井无线输电技术需要解决的关键问题。     

Local feedback stabilization of large interconnected power systems in emergencies

On-line stabilization of the large interconnected power system poses problems which are unusual among large systems. The system can lose stability in 2–3 s or sooner—yet, even a simplified model of it consists of hundreds or thousands of state variables. Hence, a full state identification or estimation and a dynamic control utilizing the complete system dynamics is computationally out of the question. In fact, of necessity, any centralized action must be quite limited. This leaves the challenging task of using local information to achieve system-wide stabilization. Control is also limited by practical considerations to short pulses of positive or negative power of fixed magnitude.A nonlinear transformation which maps the conventional state space of the power system into a new observation decoupled state space is introduced and shown to be a homeomorphism. This state space has the property that its components can be measured piecemeal in local groups and its origin is the unique stable equilibrium point of the power system when one exists. It is then shown that a feedback control, based on such local information, is capable of assuring system-wide approach to the stable equilibrium point. The existence of a stability region for this local feedback control is also shown.     

基于速龙码的WSNs传输功率控制重编程协议

为了降低节点能耗,提高能量的利用率,提出了一种高效节能的基于速龙码（ RC）的传输功率控制（ RC-TPC）重编程协议。该协议分两个阶段完成数据传输,第一阶段各个节点更新自己的位置信息,形成最优化的拓扑结构。进入第二阶段后,根据优化的拓扑结构通过调整发送节点的传输功率和中继节点的累计选择次数,Sink节点选择适当的中继节点,使中继节点的传输功率和RC的开销达到最优化。此外,RC的编码方式使传输数据包发生的错误概率更小,减少了重编程过程中的冗余以保证网络负载的均匀分布,有效地实现了高效节能,从而提高整个网络的生存周期。理论分析与实验结果表明：与MNP协议和ATPC协议相比,RC-TPC协议用于传输的平均能量消耗降低17.2%。