Stability and Control of a Parametrically Excited Rotating System. Part I: Stability Analysis

This paper analyses the stability of a parametrically excited double pendulum rotating in the horizontal plane. The equations of motion for such a system contain time varying periodic coefficients. Floquet theory and the method of Hill's determinant are used to evaluate the stability of the linearized system. Stability charts are obtained for various sets of damping, parametric excitation, and rotation parameters. Several resonance conditions are found, and it is shown that the system stability can be significantly altered due to the rotation. Such systems can be used as preliminary models for studying the lag dynamics and control of helicopter blades and other gyroscopic systems.     

Application of PPP Technology and Airborne Lidar in Power Line Inspection

Through the power line test,this paper presents the feasibility of applying the PPP technology of GPS,GLONASS and BDS multi-source fusion to verify the application of the generated POS data and 3D point cloud data to the high voltage power line inspection.The POS data fusion and calculation of different strategies are used to analyze the POS data accuracy of the POS data,GPS,GLONASS and BDS multi-systems under the base station differential POS data and the single GPS system.The 3D point cloud is generated by the POS data of different strategies,and the deviation distance and distribution of differential point cloud data are statistically analyzed.Finally,it is concluded that the point cloud data generated by the single GPS is about 20-40 cm,and the distribution is not uniform and the deviation distance fluctuates greatly.It can not meet the requirement of the fine inspection of the power line.The point cloud data generated by the PPP technology of multi-source fusion and the distance deviation from the point cloud data under the base station difference are 10 cm in the direction of X,The direction of Y is 6 cm and the direction of Z is 4 cm.The distribution of point cloud data is uniform and stable,which basically meets the requirements of the power line inspection,and the point cloud data can also be used for the fine inspection of the power line.     

基于频响函数识别直升机尾传动轴系非线性的方法

提出了基于测试频响函数识别尾传动轴系非线性模态参数的方法。利用线性的模态分析技术,并结合响应幅值线性化理论,通过步进正弦扫频测试激励尾传动轴系,得到直升机尾传动轴系不同激励水平下的频响函数信息,最终识别出尾传动轴系的非线性模态参数。分析结果表明:随着激励力幅值的增大,尾传动轴系的一阶固有频率减小约2%,而阻尼比增大约1.5倍,且在同一状态下多组试验分析结果一致。提出的识别尾传动轴系非线性模态参数的方法,为进一步精确研究直升机尾传动轴系的动力学特性奠定了基础。     

小型无人直升机模型辨识数据处理方法研究

针对小型无人直升机模型频域辨识过程中的姿态角速率测量误差,提出了一种飞行数据处理方法。该方法采用飞行试验扫频测试技术,确保激励信号能够满足不同频段下模型辨识对飞行数据的需求;设计基于有色噪声的卡尔曼滤波器以降低紊流风场对飞行测量数据的影响,同时,对飞行测量数据使用数据预处理的方法以剔除测量噪声、野值、直流成分和低频分量。在小型无人直升机系统各通道中进行验证,验证结果表明,所提出的飞行数据处理方法能够满足小型无人直升机模型辨识对姿态角速率数据精度的要求,为精确建模提供了较高质量的飞行数据。     

直升机大球铰摆动和滑动磨损试验机测控系统设计

直升机大球铰摆动、滑动磨损试验机可以真实地模拟大球铰在直升机上的运转和受载荷状态.试验机测控系统主要解决运动模式和力加载的协调运动,设计关键算法解决了任意更换滑动行程、滑动频率和摆动角、摆动频率的4个参数对运动曲线的拟合问题,生成3个缸的位置时域序列,解决了任意方向力加载的难点,模拟大球铰受力情况,实现了大球铰在不同飞行状态下运动和受载荷的自动运行.通过合理的硬件设计和软件开发,其自动化程序高、界面友好、运行稳定,为直升机大球铰疲劳磨损试验数据的准确性和可靠性提供了保证.     

基于PEM的三自由度直升机模型辨识

针对三自由度(3-DOF)直升机平台的特点,提出了一种基于预测误差法(PEM)的模型频域辨识方法,建立了机理模型,运用扫频技术得到巡航飞行状态直升机3个通道的输入-输出数据;分析了偏相干函数和复合窗函数,通过PEM进行了模型的频域辨识,得到了状态空间方程的待辨识参数和直升机的参数化模型.通过时域飞行和模型预测响应的对比,验证了该模型的准确性和该辨识方法的有效性.     

无人直升机基于视觉的静止点目标跟踪*

针对带有摄像机的直升机进行静止点目标跟踪的情况,提出了一种层级控制器。该控制器共有三个回路：内回路采用四个独立的PD控制器控制直升机的高度和姿态;中间回路利用两个Mamdani型模糊控制器控制直升机的位置;外回路利用视觉反馈获得直升机下一步的期望位置,其不需要已知摄像机的内参数和平移外参数以及目标点的坐标,只需已知粗略标定的旋转外参数。仿真结果表明了该控制器的可行性。     

Method to Monitor Helicopter Rotor Fault Using Diagnostic Matrix

An efficient method for helicopter rotor fault diagnosis was proposed using diagnostic matrix and its software framework was developed.The diagnostic matrix was extracted by the way of simulating the quantitative models of damaged and undamaged rotor systems.The conflicts were recognized by the virtual symptom sensor based on the dependencies between symptoms and faults.Diagnostic candidates were generated by the Boolean hitting algorithm.The proposed method provides multi-fault real-time diagnostic capabil...     

地面仿真试验中模拟驾驶员操纵的工程方法

在直升机飞行控制系统、尤其是控制增稳系统的地面仿真试验中,实施标准的、具有可重复性的杆操纵非常重要.提出了两种在地面仿真试验中模拟驾驶员操纵的新方法,结合设计框图以及地面试验结果,总结了两种方法的优缺点.工程实践表明,这两种操纵方式为准确、有效地进行开环、闭环试验及品质评定提供了方便,并取得了较好的结果.该方法也可借鉴到固定翼等其他系统的地面仿真试验中.     

直升机自动驾驶仪测试系统软件的设计与实现

针对直升机自动驾驶仪装机前的性能检测,设计了直升机自动驾驶仪测试系统软件。详细叙述了自动驾驶仪测试系统软件的设计方案,重点分析了RS-485总线冲突的解决方案,基于Modbus协议数据包的解读机制,测试软件实时性的保证。实时测试软件采用模块化设计思想,实现了测试的自动化和综合化,实际应用表明,该测试软件操作简便,运行稳定可靠。