Underactuated spacecraft angular velocity stabilization and three-axis attitude stabilization using two single gimbal control moment gyros

Angular velocity stabilization control and attitude stabilization control for an underactuated spacecraft using only two single gimbal control moment gyros （SGCMGs） as actuators is investigated. First of all, the dynamic model of the underactuated spacecraft is established and the singularity of different configurations with the two SGCMGs is analyzed. Under the assumption that the gimbal axes of the two SGCMGs are installed in any direction, and that the total system angular momentum is not zero, a state feedback control law via Lyapunov method is designed to globally asymptotically stabilize the angular velocity of spacecraft. Under the assumption that the gimbal axes of the two SGCMGs are coaxially installed along anyone of the three principal axes of spacecraft inertia, and that the total system angular momentum is zero, a discontinuous state feedback control law is designed to stabilize three-axis attitude of spacecraft with respect to the inertial frame. Furthermore, the singularity escape of SGCMGs for the above two control problems is also studied. Simulation results demonstrate the validity of the control laws.

A Three-Axis Robot Using a Remote Network Control System

For the petroleum industry, to reduce the risk of a gas explosion in dangerous working areas, the use of explosion-proof equipment such as air-driven devices which are free from explosions becomes essential. Moreover, for the purpose of saving manpower, a remote operation using a robot via a visual monitoring system and a network is used. However, to overcome the drawback of costly manpower and to improve safety in explosion-prone zones, a three-axis robot using a remote network control system is proposed. In this paper, the three-axis robot can be monitored online via the USB protocol. Furthermore, it also can be remotely manipulated via the TCP/IP protocol by clicking the command of the VB interface on the client pc. Consequently, the remote-control three-axis robot can not only work for people in severe and dangerous circumstances but also can reduce the cost of manpower.

IMPROVED QUANTITATIVE FEEDBACK THEORY TECHNIQUE AND APPLICATION TO THREE-AXIS HYDRAULIC SIMULATOR

In order to meet tracking performance index of three-axis hydraulic simulator, based on classical quantitative feedback theory （QFT）, an improved QFT technique is used to synthesize controller of low gain and bandwidth. By choosing a special nominal plant, the improved method assigns relative magnitude and phase tracking error between system uncertainty and nominal control plant. Relative tracking error induced by system uncertainty is transformed into sensitivity problem and relative tracking error induced by nominal plant forms into a region on Nichols chart. The two constraints further form into a combined bound which is fit for magnitude and phase loop shaping. Because of leaving out pre-filter of classical QFT controller structure, tracking performance is enhanced greatly. Furthermore, a cascaded two-loop control strategy is proposed to heighten control effect. The improved technique＇s efficacy is validated by simulation and experiment results.

Misalignment Angle Calculation Accuracy Analysis of Three-Axis Stabilized Geostationary Satellite

The most challenging problem of navigation in three-axis stabilized geostationary satellite is accurate calculation of misalignment angles, deduced by orbit measurement error, attitude measurement error, thermal elastic deformation, time synchronization error, and so on. Before the satellite is launched, the misalignment model must be established and validated. But there were no observation data, which is a non-negligible risk of yielding the greatest returns on investment. On the basis of misalignment modeling using landmarks and stars, which is not available between different organizations and is developed by ourselves, experimental data are constructed to validate the navigation processing flow as well as misalignment calculation accuracy. In the condition of using landmarks, the maximum misalignment calculation errors of roll, pitch, and yaw axis are 2, 2, and 104 micro radians, respectively, without considering the accuracy of image edge detection. While in the condition of using stars, the maximum errors of roll, pitch, and yaw axis are 1, 1, and 3 micro radians, respectively, without considering the accuracy of star center extraction. Results are rather encouraging, which pave the way for high-accuracy image navigation of three-axis stabilized geostationary satellite. The misalignment modeling as well as calculation method has been used in the new generation of geostationary meteorological satellite in China, FY-4 series, the first satellite of which was launched at the end of 2016.

The Impact Study of Three-axis Servo System Interference Torque based on Virtual Prototype

The three-axis servo system with the core of gyro stabilization is the foundation to realize its function, and a key technology of the seeker devolopment. In order to reduce the costs, improve the efficiency of research and devolopment, a new method that instead of physical prototype by virtual prototype was proposed. Adams and MATLAB/simulink are used to establish the mechanical dynamics model and controller model of the three-axis servo system. The simulation data which was processed and analyzed is compared with test data, to determine the control parameters of the virtual prototype and improve the accuracy of the model, and test the multiple condition simulation,which can provide a reference for practical production.The simulation results verify the feasibility of the models.

CMG框架超低速无电流环矢量控制研究

针对控制力矩陀螺框架在超低速工况下存在转速测量精度低、多源扰动力矩及非线性摩擦等问题,提出了基于无电流环矢量控制的超低速驱动控制方法。首先,建立超低速工况下的框架电机的机电模型,设计了无电流环磁场矢量控制器(field-oriented control,简称FOC);其次,针对转速测量精度的问题,设计了转速观测器作为反馈环节。结果表明,与方波驱动法相比,该方法无换相转矩,提高了转速测量精度,且在面对多源扰动、非线性摩擦时具有鲁棒性。仿真和实验结果验证了该方法的可行性和有效性。

基于Gimbal的手机情境感知应用开发

解释了情景感知的定义,介绍了Gimbal开发平台能够高效、方便地帮助开发者实现手机情景感知应用的开发,给出了应用该平台开发一个校园位置感知的手机应用的细节。

基于扩张状态观测器的无人机云台系统控制算法

针对无人机(UAV)三轴云台增稳控制中变量耦合的问题,提出一种基于扩张状态观测器(ESO)的无人机云台系统控制算法。首先,建立了无人机机载云台期望角的姿态解算算法模型;其次,构建了无人机机载云台位置环和速度环的串级比例-积分-微分(PID)控制回路;最后,引入ESO对机载云台角速度项在线实时估计,解决角速度项由于高耦合、多外扰导致的难以直接测量的问题,并对各通道的控制输入进行补偿。实验结果表明,所提算法在无指令、有指令和综合任务场景下的角度均方根误差分别为0.2357°、0.6317°和0.9463°,与传统PID算法相比,所提算法的角度误差分别降低了69.43%、53.29%和50.43%。可见,所提算法对外界扰动的抗干扰能力更强,控制精度更高。

空间激光终端二维转台U型架结构优化设计

空间激光终端二维转台是建立星地/星间高精度激光通信链的关键部件,其U型架结构的性能直接影响转台的稳定性和测量精度。为了适应发射阶段载荷过载及满足空间环境的严苛要求,文中提出了一种基于铝基碳化硅材料的U型架结构优化设计方案。该方案综合考虑材料特性和结构布局,对U型架的11种典型尺寸参数进行了分析和优化,实现了结构的轻量化和高刚度。研究发现,U型架支撑端厚度和侧肋斜率是影响其一阶基频和重量的关键因素。仿真结果表明,优化后的U型架质量减轻了25.03%,一阶基频提高了85.48Hz。实物U型架随二维转台的力学试验验证表明,二维转台的整体性能和可靠性得到了有效提升。

多旋翼无人机增稳云台的优化设计

针对现有无人机增稳云台在通用性、结构稳定性等方面存在的问题,优化设计了一种能够兼容大多数无人机的多旋翼无人机增稳云台。对现有无人机增稳云台的两种典型结构进行ANSYS软件仿真分析,通过改变减振球数量、分布位置和减振板外形,来进行优化设计,得到多旋翼无人机增稳云台。在ANSYS软件中对优化设计的多旋翼无人机增稳云台进行静力学与预应力模态分析,数据表明强度、刚度符合要求,并且具有良好的动态性能。

高炉煤气流监测装置及应用

介绍了一种高炉煤气流监测装置的结构及应用效果。通过对炉顶不同方向煤气流的温度检测与比值计算,实现对其发展程度和趋势的数据化精准判断,有效解决传统十字测温装置造成的料面拉沟问题,稳定了高炉煤气流分布,提高了煤气利用率。

基于深度学习的无人机目标识别与反制

随着低空无人机在军事和民用领域的广泛应用,其安全隐患亟需关注。本文提出一种基于改进YOLOv7模型的检测方法,并引入注意力机制,强化模型对目标区域特征的表达能力。同时,提出一种改进的StrongSORT跟踪算法,优化跟踪性能。这些研究成果提高了检测和跟踪的准确性和实时性,通过云台主动跟踪控制算法扩大了监控视野,增强了系统的跟踪灵活性。最终实现了一套完整的红外无人机检测与跟踪系统,满足了实时跟踪的需求,并探讨了其在民用领域反无人机系统中的潜在应用。

Application of Ultrasonic Motor to Control of Moment Gyroscope Gimbal Servo System

Attitude control system is one of the most important subsystems in a spacecraft.As a key actuator,the control moment gyroscope(CMG)mainly determines the performance of attitude control system.Whereas,the control accuracy and output torque smoothness of the CMG depends more on its gimbal servo system.Considering the constraints of size,mass and power consumption for a small satellite,here,a mini-CMG is designed,in which the gimbal servo system is driven by an ultrasonic motor.The good performances of the CMG are obtained by both the ultrasonic motor and the rotary inductosyn.The direct drive of gimbal improves its dynamic performance,with the output bandwidth above 20 Hz.The angular and speed closed-loop control obtains the 0.02°/s gimbal rate,and the output torque resolution better than 2×10^(-3) N·m.The ultrasonic motor provides 1.0N·m self-lock torque during power-off,with 12arc-second position accuracy.

RESEARCH AND SIMULATION OF THE INFLUENCE OF THREE-AXIAL COMPACTION ON POWDER METALLURGIC PRODUCT PROPERTIES

The warm powder compaction process is simulated by the finite element analysis software, MSCJMARC. The thermal mechanically coupled analysis method is applied on the basis of the updated Lagrangian Method, to simulate the warm powder compaction process. The warm powder compaction process is simulated, and the influence of friction condition and pressing styles are researched on the density of powder green and the mechanics behavior at certain temperature. The results indicate that for cylindrical compacts, with the improvement of the friction condition, the uniformity of distribution of green relative density is largely improved, the pressing force and stress decrease, and the nonconforming pressing processes influence the distribution of green density to some degree. The status of stress distribution of the process that punches firstly press and die finally press is different from the other three processes, and presents the figure of ＇flume ＇.

Mechanical properties of copper nanocube under three-axial tensile loadings

The mechanical properties of copper nanocubes by molecular dynamics are investigated in this paper. The [100], [110], [111] nanocubes are created, and their energies, yield stresses, hydrostatic stresses, Mises stresses, and the relation- ships between them and strain are analyzed. Some concepts of the microscopic damage mechanics are introduced, which are the basis of studying the damage mechanical properties by molecular dynamics. The [100] nanocube exhibits homo- geneity and isotropy and achieves a balance easily. The [110] nanocube presents transverse isotropy. The [111] nanocube shows the complexity and anisotropy because the orientation sizes in three directions are different. The broken point occurs on a surface, but the other two do not. The [100] orientation model will be an ideal model for studying the microscopic damage theory.

Modeling and Simulation of Two Axes Gimbal Using Fuzzy Control

The application of the guided missile seeker is to provide stability to the sensor’s line of sight toward a target by isolating it from the missile motion and vibration.The main objective of this paper is not only to present the physical modeling of two axes gimbal system but also to improve its performance through using fuzzy logic controlling approach.The paper is started by deriving the mathematical model for gimbals motion using Newton’s second law,followed by designing the mechanical parts of model using SOLIDWORKS and converted to xml file to connect dc motors and sensors using MATLAB/SimMechanics.Then,a Mamdani-type fuzzy and a Proportional-Integral-Derivative(PID)controllers were designed using MATLAB software.The performance of both controllers was evaluated and tested for different types of input shapes.The simulation results showed that self-tuning fuzzy controller provides better performance,since no overshoot,small steady-state error and small settling time compared to PID controller.

单旋翼无人机云台振动试验研究

单旋翼无人机机载设备受振动影响会导致无人机姿态不稳,对此进行了试验研究。选取合适的测量点,对云台起飞和飞行2个工况下的振动信号进行采集,获取云台的时域响应和功率谱密度。结合减振系统的动力学模型,提出无人机云台减振方案,通过无人机实地飞行试验表明,减振后振动时域响应和功率谱密度降低明显。该减振方案可为无人机减振设计提供有效依据。

惯性稳定万向架中基于SBG惯导的捷联控制技术

轻小型SBG惯性导航系统具有体积小重量轻的特点,可以用于光电跟踪系统的直接及捷联位置稳定。本文研究了万向架中基于轻小型SBG惯导的五种惯性稳定控制方法,并进行了理论分析及实验验证。经典位置捷联稳定技术由于位置带宽的限制扰动抑制能力有限,难以满足高精度稳定要求。本文提出了一种基于SBG的位置速度双扰动前馈的稳定方法,并通过引入高通滤波器实现扰动前馈的解耦,可以进一步提升系统扰动抑制带宽以及稳定能力。理论分析和实验结果表明:在不考虑应用条件的限制时,虽然受到带宽的限制,基于SBG的陀螺直接稳定控制方法扰动抑制效果较好;而在平台体积重量受到限制的情况下,所提出的基于SBG的双扰动捷联稳定可以进一步提升系统扰动抑制能力,获得更好的稳定精度。

线性自抗扰的增稳云台控制系统研究与实现

增稳云台是维持摄像头稳定并获得清晰图像的重要装置。文中提出一种LADRC线性自抗扰控制算法与FOC矢量控制算法相结合的方法,并将其应用于增稳云台系统中,提高增稳云台的控制精度、稳定性与抗干扰能力。其次,对无人系统增稳云台的硬件和软件进行设计,搭建测试实验平台。测试结果表明,所设计的控制系统运行良好,对阶跃控制命令的上升时间在0.3 s以内,在17.5 m/s的风速环境下,三轴角度的变化范围在0.15°以内,可达到预期目标。