Command Filtered Finite/Fixed-time Heading Tracking Control of Surface Vehicles

This paper investigates the heading tracking problem of surface vehicles with unknown model parameters.Based on finite/fixed-time control theories and in the context of command filtered control,two novel adaptive control laws are developed by which the vehicle can track the desired heading within settling time with all signals of the closed-loop system are uniformly bounded.The effectiveness and performance of the schemes are demonstrated by simulations and comparison studies.

High resolution tracking of adult horseshoe crabs Limulus polyphemus in a New Hampshire estuary using fixed array ultrasonic telemetry

While several studies have documented the large-scale, seasonal movements of horseshoe crabs, little is known about their fine-scale, daily movement patterns. In this study we used a fixed array ultrasonic telemetry system to track the movements of 12 male and 16 female horseshoe crabs in the Great Bay estuary, New Hampshire. Data were obtained during the mating season, as well as during the remainder of the summer and fall, in the years 2005-2008. During the mating season animals were often, but not always, active during the high tides when they were approaching and leaving the spawning beaches. On average, both males and females approached mating beaches during 33% of the high tides they experienced and they most often made the tran- sition from being inactive to active during the last two hours of an incoming tide. From April-October horseshoe crabs were significantly more active during high tide periods vs low tide periods, with no clear preference for diurnal vs nocturnal activity. After the mating season ended horseshoe crabs continued to move into shallower water at high tide and then return to deeper water at low tide. Observations by SCUBA divers suggest that during these excursions into the mudflats horseshoe crabs were digging pits in the sediment while foraging for food. Thus, the tidal rhythm of activity that has been so well documented during the mating season probably persists into the fall, and primarily involves foraging activities

Lock threshold deterioration induced by antenna vibration and signal coupling effects in hypersonic vehicle carrier tracking system of Ka band

The envelope of a hypersonic vehicle is affected by severe fluctuating pressure, which causes the airborne antenna to vibrate slightly. This vibration mixes with the transmitted signals and thus introduces additional multiplicative phase noise. Antenna vibration and signal coupling effects as well as their influence on the lock threshold of the hypersonic vehicle carrier tracking system of the Ka band are investigated in this study. A vibration model is initially established to obtain phase noise in consideration of the inherent relationship between vibration displacement and electromagnetic wavelength. An analytical model of the Phase-Locked Loop（PLL）, which is widely used in carrier tracking systems, is established. The coupling effects on carrier tracking performance are investigated and quantitatively analyzed by imposing the multiplicative phase noise on the PLL model. Simulation results show that the phase noise presents a Gaussian distribution and is similar to vibration displacement variation. A large standard deviation in vibration displacement exerts a significant effect on the lock threshold. A critical standard deviation is observed in the PLL of Binary Phase Shift Keying（BPSK） and Quadrature Phase Shift Keying（QPSK） signals. The effect on QPSK signals is more severe than that on BPSK signals. The maximum tolerable standard deviations normalized by the wavelength of the carrier are 0.04 and 0.02 for BPSK and QPSK signals,respectively. With these critical standard deviations, lock thresholds are increased from à12 andà4 d B to 3 and à2 d B, respectively.

Experimental Study of a Modified Command Governor Adaptive Controller for Depth Control of an Unmanned Underwater Vehicle

Command governor–based adaptive control(CGAC)is a recent control strategy that has been explored as a possible candidate for the challenging task of precise maneuvering of unmanned underwater vehicles(UUVs)with parameter variations.CGAC is derived from standard model reference adaptive control(MRAC)by adding a command governor that guarantees acceptable transient performance without compromising stability and a command filter that improves the robustness against noise and time delay.Although simulation and experimental studies have shown substantial overall performance improvements of CGAC over MRAC for UUVs,it has also shown that the command filter leads to a marked reduction in initial tracking performance of CGAC.As a solution,this paper proposes the replacement of the command filter by a weight filter to improve the initial tracking performance without compromising robustness and the addition of a closed-loop state predictor to further improve the overall tracking performance.The new modified CGAC(M-CGAC)has been experimentally validated and the results indicate that it successfully mitigates the initial tracking performance reduction,significantly improves the overall tracking performance,uses less control force,and increases the robustness to noise and time delay.Thus,M-CGAC is a viable adaptive control algorithm for current and future UUV applications.

Simulation method for reliability of TT&C mission with high redundancy and small time horizon

The tracking, telemetry and command （TT＆C） mission is extremely reliable for its characters of small time horizon and high redundancy. The combined forcing and failure biasing （CFFB） method that is usually used for simulating the unreliability of the highly dependable mission system seems not so efficient for the TT＆C mission. The concept about the importance of failure transition is proposed based on the logical relationship between TT＆C mission and its involved resources. Then, the importance is used for readjusting the transition rate of the failure transition when using the forcing and failure biasing during the simulation. Examples show that the improved CFFB method can evidently increase the occurrence of the TT＆C mission failure event and decrease the sample variance. More redundancy of the TT＆C mission leads to the improved CFFB method more efficient.

基于双卫星导航接收机的测控装备精度验收方法研究

针对测控装备精度验收的问题,提出了采用双卫星导航接收机的测控装备精度验收方案,给出精度验收的一般流程,详细推导了一种不同于传统的真值计算新方法,并提供了此方法的具体算法和模型。在理论分析的基础上,采用算例进行计算和分析,结果表明基于双卫星导航接收机的测控装备精度验收方法,可以事先根据测控装备的精度指标,分析所需卫星导航接收机的指标,同时也可以为航路设计提供定量数据支撑,节省测控装备精度验收的人力与物力,可以在测控装备精度验收的相关领域推广应用。

一种航天测控冗余跟踪弧段处理方法

随着在轨航天器的日益增多,测控资源的需求量也日益增大,因此,其使用效率也倍受关注。当航天器重要测控弧段安排多个测控设备进行全力跟踪时,很容易出现测控弧段搭接或完全被覆盖的情况。为有效利用现有测控资源,针对弧段搭接的情况,提出了一种基于冗余度评价函数的跟踪弧段处理方法,该方法在不降低跟踪总时长情况下,通过合理有效地配置测控资源,剔除了冗余跟踪弧段,提高了现有测控资源的使用效率。

智能天地一体化网络的卫星跟踪测控技术综述

随着卫星互联网和我国航天测控技术的不断进步,航天测控网络朝着智能化、一体化的方向发展,在自主测控、资源分配等方面进展良好。因此,建立智能天地一体化的航天测控网是我国航天未来发展的重要目标。针对智能航天测控网中的跟踪测轨、遥测和遥控三个方面,分别介绍了相关原理与技术。同时,结合CCSDS提出的空间数据链路标准协议详细介绍了TM、TC、AOS、Proximity-1以及USLP标准,分析了不同标准所使用的技术与实际应用。本文从数据链路层和物理层的角度介绍了智能航天测控系统的工作原理及技术要求,为我国智能天地一体化卫星测控通信网的研究提供参考并予以展望。

基于遥测姿态变换的外测数据跟踪部位修正方法

外测数据跟踪部位修正对于飞行器飞行试验的高精度轨迹参数获取有着重要意义.提出一种基于飞行器遥测姿态数据和粗略轨迹参数的跟踪部位修正新方法,利用遥测姿态数据确定惯导平台中心与跟踪部位轨迹参数的变换关系,进而由粗略轨迹参数推算惯导平台中心与跟踪部位测距、径向速度、方位角和俯仰角的差异值,实现跟踪部位修正量的准确计算.采用误差传播法对粗略轨迹误差影响下的跟踪部位修正精度进行理论分析,验证了该修正方法在实际应用中的有效性.进一步通过仿真实验和实装实验检验了修正精度.结果表明跟踪部位修正量的计算误差远小于外测系统的精度指标要求,有重要的实际应用价值.

电动履带式运输机智能语音控制系统的设计

采用语音识别模块,识别语音命令词控制电动履带式运输机。语音识别模块通过应用配置相关工作模式、识别语音命令词和发送识别语音后对应的通信命令,MCU接收、解析识别语音后对应的通信命令帧,并根据通信命令帧控制履带式运输机前进、后退、左转、右转、车斗升降以及语音播放执行命令的操作。

考虑输入饱和的无人艇神经网络命令滤波反步控制

针对具有输入饱和和未知非线性的无人水面艇(USV)系统的轨迹跟踪控制问题,提出一种基于命令滤波反步的自适应轨迹跟踪控制策略。利用径向基函数神经网络(RBFNN)逼近系统中的未知动态,减少了需要设计的自适应律数量,降低了系统的复杂度,并基于反步法设计了系统的控制律;通过引入命令滤波器及其补偿机制,解决了计算复杂的问题,消除了滤波误差的影响,提高了系统的控制精度;最后仿真验证了所提方法的有效性。

知识图谱和大语言模型在航天测控问答系统中的融合应用研究

随着自然语言处理技术的发展,智能化检索与问答系统不断发展,为改善传统知识图谱语义解析能力不足和当前通用大语言模型在垂直领域对知识学习不够深入的问题,提出了融合知识图谱的大语言模型方法,进行了两步优化:首先,利用知识图谱在命名实体识别和关系抽取的基础上,构建大模型提示Prompt模板,进行辅助增强生成,利用图谱中存储的数据提供相关来源;其次,利用低阶适应性微调(LoRA)策略冻结大模型原有参数,增加部分网络参数进行微调训练,优化模型在航天测控领域的知识储备与理解。通过两步改进提高了模型整体在语义解析和知识细节上的理解掌握,结合航天测控领域的相关教材、报告和手册等资料,搭建了知识问答系统,取得了较好的效果,说明了该方法具有一定的应用价值。

基于命令滤波反推方法的水面无人艇容错编队跟踪控制

研究了具有模型不确定性和执行器故障的多水面无人艇系统的编队跟踪控制问题。通过在线信息交互,为跟随无人艇设计完全分布式观测器以估计期望的位置、航向和速度,并提出命令滤波反推控制协议。该控制协议实现了闭环误差系统的实用指数稳定性及多无人艇系统的编队跟踪。该控制方法的一个优点是不依赖于通信拓扑图Laplacian矩阵的谱信息,使得提出的控制协议能在完全分布式架构下实施。仿真实验验证了该控制协议的有效性。

基于模型预测控制算法的精确着舰控制方法

针对舰载机着舰过程中的航母运动、舰尾流扰动等影响,提出一种基于模型预测控制-线性二次型高斯(MPC-LQG)算法的精确着舰控制方法,开展飞机纵向通道的精确着舰控制研究。对飞机纵向动力学、舰尾流、航母运动、轨迹跟踪等,进行建模和分析。对MPC-LQG算法进行融合,以实现轨迹跟踪控制,核心思想是:模型预测控制进行航母运动补偿;设计全维状态观测,实现全状态反馈,以实现最优着舰控制。对不同的着舰情况和初始条件进行算法仿真,并与其他算法进行仿真比较。仿真结果表明,所提方法的轨迹跟踪效果很好,高度偏差0.1~0.2 m;相比传统着舰控制,所提方法动态响应快、着舰精度高。

智能化验机器人控制指令网络传输优化系统

海量控制指令在传输过程中容易引起网络传输时延,为避免该情况的发生,设计智能化验机器人控制指令网络传输优化系统。硬件部分以微控制器为基础,通过RS-232串口控制指令网络传输时延;设计控制指令网络传输电路,通过SPI接口输出数据;使用请求/应答传输结构,获取控制指令序列。软件方面设计数据传输控制时序获取响应信号;引入正交匹配追踪算法,计算经过稀疏重构的信号输出结果;结合系统端对端时钟同步算法,实现控制指令网络传输优化。由实验结果可知,该系统最大平均吞吐量为560 b/s,最快传输速率为110 kbps,具有较优的传输效果。

时变输出约束机械臂系统渐近跟踪控制

针对非对称时变输出约束的机械臂系统,提出了一种基于事件触发的自适应渐近跟踪控制策略。首先,采用自适应命令滤波反步方法,解决了“计算爆炸”问题;同时,利用时变非对称李雅普诺夫函数,可以保证闭环系统的渐近稳定性且系统状态满足非对称时变约束条件;此外,自适应渐近跟踪控制可以保证在存在不匹配扰动的情况下,跟踪误差渐近收敛于零。该控制器设计采用了事件触发控制策略,在必要时产生控制输入,减少通信负担,提高了控制性能;最后,通过对非对称时变约束下的双连杆机械臂系统进行仿真,验证了该方法的有效性。

单线双方向区间自动闭塞结合电路工程设计优化方案

在单线双方向四显示自动闭塞区间,计算机联锁控显终端界面同一进站口的接近/离去表示灯存在同时点红灯的情形,给行车指挥带来不便。根据车站运营维护单位的实际需求,在不改变计算机联锁软件的前提下,引入四线制方向电路中区间正方向继电器QZJ、区间反方向继电器QFJ条件,提出2种JGJ、LQJ励磁电路优化设计方案。从电路原理、实现效果、施工工作量等角度对2种方案进行比选,推荐采用QZJ/QFJ接点与GJF接点并联的优化方案。该优化方案中,JGJ、LQJ的继电器状态包含相应闭塞分区占用情况和区间实际运行方向双重含义,可实现计算机联锁控显终端按区间开通方向分别显示接近/离去表示灯,同时不影响JGJ、LQJ参与的其他继电电路,可为后续类似项目的工程设计提供参考。

Hierarchical Disturbance Propagation Mechanism and Improved Contract Net Protocol for Satellite TT&C Resource Dynamic Scheduling

The practical engineering of satellite tracking telemetry and command(TT&C)is often disturbed by unpredictable external factors,including the temporary rise in a significant quantity of satellite TT&C tasks,temporary failures and failures of some TT&C resources,and so on.To improve the adaptability and robustness of satellite TT&C systems when faced with uncertain dynamic disturbances,a hierarchical disturbance propagation mechanism and an improved contract network dynamic scheduling method for satellite TT&C resources were designed to address the dynamic scheduling problem of satellite TT&C resources.Firstly,the characteristics of the dynamic scheduling problem of satellite TT&C resources are analyzed,and a mathematical model is established with the weighted optimization objectives of maximizing the revenue from task completion and minimizing the degree of plan disturbance.Then,a bottom-up distributed dynamic collaborative scheduling framework for satellite TT&C resources is proposed,which includes a task layer,a resource layer,a central internal collaboration layer,and a central external collaboration layer.Dynamic disturbances are propagated layer by layer from the task layer to the central external collaboration layer in a bottom-up manner,using efficient heuristic strategies in the task layer and the resource layer,respectively.We use improved contract network algorithms in the center internal collaboration layer and the center external collaboration layer,the original scheduling plan is quickly adjusted to minimize the impact of disturbances while effectively completing dynamic task requirements.Finally,a large number of simulation experiments were carried out and compared with various comparative algorithms.The results show that the proposed algorithm can effectively improve the solution effect of satellite TT&C resource dynamic scheduling problems,and has good application prospects.

CCSDS统一空间数据链路协议应用分析

针对TM、TC、AOS、Proximity-1四种空间数据链路协议的应用局限性,对CCSDS(国际空间数据系统咨询委员会)提出的统一空间数据链路协议(Unified Space Data Link Protocol,USLP)规范进行分析,介绍了USLP传输帧主导头和数据域中各个字段的设计驱动,以及与其他空间数据链路协议的差异。对于服务数据单元信道复用传输需求,梳理了物理信道、主信道、虚拟信道、多路复用访问信道的服务类型,明确了数据传输服务、信道复用、信道标识、服务数据单元之间的关联关系。以遥测遥控数据空间链路传输为例,分析了USLP的适用性和推荐设置。

基于射频指纹的卫星测控地面站身份识别方法

传统卫星测控通常采用加密认证安全机制,存在身份假冒、欺骗等安全问题,该文提出一种基于射频指纹的卫星测控地面站身份识别方法,并设计了一种面向星载平台的轻量化卷积神经网络。该网络首先使用IQ方向上的卷积层提取IQ信号相关特征,将2维数据降成了1维,再使用时序方向上的多层卷积提取信号的时域结构特征,之后使用最大池化层降低数据维度,在充分利用IQ信号中包含的原始特征信息的同时减小计算量,最后经过两层全连接层进行分类,实现对卫星测控地面站身份识别。仿真实验表明,该方法对21台发射机个体的平均准确率为93.8%,较传统的支持向量机方法提高了39.8%,较DLRF网络模型、ORACLE网络模型分别提高了11.5%,29.8%,且具有鲁棒性强、轻量化的优点。该文所提方法对于提高卫星测控链路安全性具有一定的理论参考和工程应用价值。