Backstepping sliding mode control with self recurrent wavelet neural network observer for a novel coaxial twelve-rotor UAV

The robust attitude control for a novel coaxial twelve-rotor UAV which has much greater payload capacity,higher drive capability and damage tolerance than a quad-rotor UAV is studied. Firstly,a dynamical and kinematical model for the coaxial twelve-rotor UAV is designed. Considering model uncertainties and external disturbances,a robust backstepping sliding mode control( BSMC) with self recurrent wavelet neural network( SRWNN) method is proposed as the attitude controller for the coaxial twelve-rotor. A combinative algorithm of backstepping control and sliding mode control has simplified design procedures with much stronger robustness benefiting from advantages of both controllers. SRWNN as the uncertainty observer is able to estimate the lumped uncertainties effectively.Then the uniformly ultimate stability of the twelve-rotor system is proved by Lyapunov stability theorem. Finally,the validity of the proposed robust control method adopted in the twelve-rotor UAV under model uncertainties and external disturbances are demonstrated via numerical simulations and twelve-rotor prototype experiments.

基于BP算法的中深层同轴套管换热量预测

通过搭建热泵测试试验台,进行多工况试验获取试验数据来建立BP神经网络同轴套管换热量预测模型,并进行仿真模拟,对同轴套管换热量进行预测。结果表明:(1)热泵系统在水流量28 m^(3)/h、回水温度10℃的工况下稳定运行能效最高,同轴套管有效换热量为563 kW。(2)隐含层节点数为12时,BP神经网络预测模型最优,训练最大均方误差MSE为0.023%,最优模型基本结构为9-12-1。(3)对比同轴套管换热量预测值与检验值仿真结果,BP神经网络同轴套管换热量预测平均百分比误差MAPE为0.235%,预测准确率为99.765%。该预测模型具有较高的精度和可靠性,能够准确预测同轴套管换热量的变化趋势,对于提高热泵系统的能效和性能具有广泛的应用价值。

Low-cost portable dielectric spectrometer based on mini-vector network analyzer and open-ended coaxial probe technology

As a simple,fast,and non-destructive measuring technology,dielectric spectroscopy is usually used to analyze the dielectric properties of agricultural products and food,and then to predict the main components of materials.However,the large and expensive vector network analyzers(VNA)with expensive analysis software applied in measuring dielectric properties make research limited to the laboratory.To acquire dielectric spectra in situ,a model for solving relative complex permittivity was derived,and its performance was validated.Then,a low-cost portable dielectric spectrometer with a mini VNA,a Raspberry Pi,and a coaxial probe as core parts was developed over the frequency range of 100-3000 MHz.The stability and accuracy of the developed spectrometer were tested using milk and juice.The results indicated that the relative errors of the model were within±5%for dielectric constant(ε′)and loss factor(ε″).The coefficients of variation of measuredε′andε″by the developed spectrometer at 100-3000 MHz were less than 1%and 2%,respectively.Compared with the dielectric properties obtained by using a commercial dielectric measurement system,the relative errors of measuredε′andε″were within±3.4%and±6.0%,respectively.This study makes fast,non-destructive,and on-site food quality detection using dielectric spectra possible.

矢量网络分析仪非同轴测量的TRL校准件设计制作

矢量网络分析仪在非同轴和高频率条件下难以实现理想的匹配负载,但通过TRL校准可降低参数要求,且精度较高。因此,本文对TRL校准技术的原理和设计原则进行介绍。以HDMI线缆测量为例,对非同轴测量TRL校准的全部环节进行论述,包括设计方法、性能验证和测量试验,为相关技术研究提供参考。

Control of Pinhole Defects Formation in Semi-flexible Coaxial Cable by Vertical Tin-Plating Process

Holistic tin-plating on the outer conductor is one of the key processes in the manufacture of semi-flexible coaxial cable, which is widely applied to the third generation (3G) mobile communication system. However, in the traditional horizontal tin-plating process, disadvantages such as the pinhole defects and low productivity effect cannot be avoided. In this paper, a vertical tin-plating process was proposed to reduce the pinhole defects and improve the tincoating quality. Compared with the traditional horizontal tin-plating process, the immersion length was reduced from 300-400 mm to 10-100 mm and the tin-plating time was reduced from 7 s to 3 s in the proposed method. The experimental results indicate that immersion length and time are key parameters for the tin-plating quality. With this new tin-plating process, the experimental results show that the pinhole defects can be eliminated effectively by controlling the immersion depth below 100 mm and tin-plating time at 3 s. The thickness of tin-coating increased from not more than 5 μm to 12.3 μm with the proposed vertical tin-plating process. Meanwhile, the thickness of the intermetallic compounds (IMCs) layer between the tin-coating and copper wires was reduced from 3.26 μm to 0.62 μm if the immersion time decreased from 30 s to 1 s. Besides, a self-developed flux, which possesses a boiling point or decomposed temperature of active components over 300℃, exhibits a better efficiency in reducing the pinhole formation.

Modeling and Robust Backstepping Sliding Mode Control with Adaptive RBFNN for a Novel Coaxial Eight-rotor UAV

This paper focuses on the robust attitude control of a novel coaxial eight-rotor unmanned aerial vehicles (UAV) which has higher drive capability as well as greater robustness against disturbances than quad-rotor UAV. The dynamical and kinematical model for the coaxial eight-rotor UAV is developed, which has never been proposed before. A robust backstepping sliding mode controller (BSMC) with adaptive radial basis function neural network (RBFNN) is proposed to control the attitude of the eightrotor UAV in the presence of model uncertainties and external disturbances. The combinative method of backstepping control and sliding mode control has improved robustness and simplified design procedure benefiting from the advantages of both controllers. The adaptive RBFNN as the uncertainty observer can effectively estimate the lumped uncertainties without the knowledge of their bounds for the eight-rotor UAV. Additionally, the adaptive learning algorithm, which can learn the parameters of RBFNN online and compensate the approximation error, is derived using Lyapunov stability theorem. And then the uniformly ultimate stability of the eight-rotor system is proved. Finally, simulation results demonstrate the validity of the proposed robust control method adopted in the novel coaxial eight-rotor UAV in the case of model uncertainties and external disturbances. © 2014 Chinese Association of Automation.

Research of Tile Type Transceiver Module Integrating with Two-Dimensional Sum Difference Network

Transceiver module and two-dimensional sum difference network are important components of phased array antenna. In this paper, multilayer printed board is used to integrate millimeter wave multi-channel transceiver circuit and sum difference network. The interconnection between them is realized through RF coaxial vertical transition. At the same time, the heat dissipation design and inter channel shielding design of the module are carried out. The RF and low frequency required by the module are completed through the wiring between and within the dielectric plate layers. Finally, 128 arrays are fabricated and verified by multi-channel passive test. The results show that the type transceiver module integrating with two-dimensional sum difference network has good performance, and 128 channels have excellent amplitude and phase characteristics. The integration technology has the characteristics of lightweight, miniaturization, high integration and low manufacturing cost. It can be widely used in miniaturized phased array antennas.

Modeling and robust adaptive control for a coaxial twelve-rotor UAV

Compared with the quad-rotor unmanned aerial vehicle (UAV), the coaxial twelve-rotor UAV has stronger load carrying capacity, higher driving ability and stronger damage resistance. This paper focuses on its robust adaptive control. First, a mathematical model of a coaxial twelve-rotor is established. Aiming at the problem of model uncertainty and external disturbance of the coaxial twelve-rotor UAV, the attitude controller is innovatively adopted with the combination of a backstepping sliding mode controller (BSMC) and an adaptive radial basis function neural network (RBFNN). The BSMC combines the advantages of backstepping control and sliding mode control, which has a simple design process and strong robustness. The RBFNN as an uncertain observer, can effectively estimate the total uncertainty. Then the stability of the twelve-rotor UAV control system is proved by Lyapunov stability theorem. Finally, it is proved that the robust adaptive control strategy presented in this paper can overcome model uncertainty and external disturbance effectively through numerical simulation and prototype of twelve-rotor UAV tests.

基于BP神经网络的液体复介电系数反演计算

实现了一种基于BP神经网络结合同轴探头计算液体复介电系数的方法。首先,应用时域有限差分法,设计了2.45 GHz频率下的同轴探头液体测量结构,通过该结构计算得到复介电系数和S_(11)参数一一对应的数据集;然后,构建了分别用于反演计算复介电系数实部和损耗角正切的两个BP神经网络模型。同时,将复介电系数和S_(11)参数的数据集用于两个BP神经网络的训练;最后,通过实验测量得到3种待测溶液的S_(11)参数,将测量得到的S_(11)参数代入训练好的BP神经网络,从而反演计算出待测溶液的复介电系数。实验结果表明,反演计算值与文献值具有较好的一致性。

采用自适应神经网络观测器的旋翼无人机容错控制

针对共轴多旋翼无人机中容易出现电机故障和复合干扰的问题,采用自适应神经网络观测器设计了容错控制算法。首先,建立了包含电机故障和复合干扰的共轴八旋翼无人机运动模型;然后,通过神经网络来逼近复合干扰,并利用自适应律估计故障因子,设计了自适应神经网络观测器对系统状态进行估计;最后,针对姿态角回路和角速度回路设计了反步容错控制律,并利用滤波器对虚拟指令信号进行滤波,抑制了微分爆炸现象,实现了共轴八旋翼UAV的渐近稳定。实验结果表明:所提方法与自适应容错控制方法相比表现出了更优的稳定性和准确性,最大跟踪误差仅为0.1°,有效补偿了复合干扰和旋翼电机故障的影响,提升了无人机的飞行稳定性和容错性能。

非同轴两轮机器人自平衡与转向闭环控制

针对车速、车身侧倾角和前轮转角变化较大工况下的非同轴两轮机器人在基于前轮转角的自平衡控制中,因动力学模型准确性对自平衡控制带来的影响,设计了基于RBF神经网络模糊滑模控制的自平衡控制器,利用RBF神经网络的逼近特性,对动力学模型中非线性时变的不确定部分进行自适应逼近,从而提高动力学模型的准确性,并借助模糊规则削弱滑模控制中产生的系统抖振;以及因前轮转角用于自平衡控制中难以实现转向闭环控制,建立了基于纯跟踪法的轨迹跟踪控制器,并设计利用车身平衡时车身侧倾角与前轮转角的耦合关系,将转向闭环控制中的目标前轮转角替换为目标车身侧倾角,从而将自平衡控制器与轨迹跟踪控制器相结合,在保证车身平衡行驶的前提下,实现带有轨迹跟踪的转向闭环控制。实验结果表明,凭借动力学模型的较高准确性,RBF神经网络模糊滑模自平衡控制器具有鲁棒性好、超调量低和响应迅速的优点,并且利用车身平衡后车身侧倾角与前轮转角耦合关系,实现转向闭环控制是可行的,具有良好的轨迹跟踪效果。

面向NGB的EoC接入网技术分析

首先论述了EoC的系列标准,然后在面向NGB的EoC技术需求白皮书的基础上对EoC技术的物理结构和物理层参数进行了分析,最后阐述了低频EoC技术和高频EoC技术的各自特点,并且对EoC技术在有线电视接入网中可能会出现的一些问题进行了分析和总结,为各地在进行EoC技术的选择时提供一定的借鉴意义。

有线电视网络的发展现状与趋势

双向化改造后的有线电视网络,既是广播电视信号的传输网络,也是宽带业务的承载网络,是有线电视运营商实现业务发展与转型的基础网络。其中有线接入网络是有线电视网络发展的关键,与用户带宽需求和有线接入技术的发展密切相关。通过调研当前国内外有线电视网络的发展现状、有线接入技术及标准的研究进展,分析了有线接入网络的发展趋势,最后对一种自主创新的吉比特同轴接入技术(HINOC)进行了介绍。

同轴法测量微波吸收材料反射率研究

为了准确方便地测量微波吸收材料（RAM）的吸波性能,提出用HP8722ET矢量网络分析仪和APC-7mm空气线进行吸波材料反射率简便测量的同轴法。研究结果表明：该方法可以测量0.05-18 GHz范围内吸波材料的反射率,无需微波暗室等实验条件;在普通实验室条件下,可以不受外界电磁波的干扰准确测量吸波材料的反射率。单层与双层吸波材料的反射率测试结果表明：同轴法测试结果与理论计算值非常吻合,比弓形法具有更高的准确性。该方法可以应用于其他型号的矢量网络分析仪和同轴空气线构成的测试系统。

基于SNMP的HFC网络管理平台设计

光纤同轴混合网是一种发展前景广阔的宽带接入技术,完善的网络管理是保证网络正常营运的基础,也是网络高效稳健运行的关键。该文提出了一种基于简单网络管理协议的光纤同轴混合网网络管理系统的解决方案,其系统包括简单网络管理协议管理站和委托代理两部分,其委托代理通过通用串行接口实现了对设备的本地管理,网络管理站通过SNMP协议和委托代理交换管理信息,从而实现了对设备的远程管理。

基于Elman网络的共轴式直升机动力学系统辨识

根据共轴式直升机动力学与运动学基本方程的结构形式建立了一种基于改进的Elman神经网络的辨识模型,同时推导了该网络的训练算法,给出了训练步骤.随后,利用外场试飞中几个典型飞行状态的遥测数据对网络进行训练,计算权值矩阵,获得该共轴式直升机用来进行动力学系统分析的神经网络模型.以匀速前飞状态为例进行了纵向操纵响应仿真,比较仿真结果和实际遥测数据可知,该网络模型基本反映了样例机的动态特性.

半导体激光器高速同轴封装设计

在光纤接入网等光通信领域,低成本高速同轴封装半导体光电器件有着非常重要的作用。对于高速TO-can激光器(LD),由于已进入微波工作频段,封装以及相关元件的分布参数已经成为制约高速激光器性能的主要参数之一,分析了同轴封装结构的技术特点,建立了激光器器件及封装相关元件的等效电路模型,利用商用CAD分析软件对其进行了模拟和优化设计,为半导体激光器高速同轴封装设计的工艺方案、封装材料的选择提供了依据,并据此进行了部分相关实验。

矢量网络分析仪时域功能及应用

矢量网络分析仪通常用来分析被测件的频域参量,为介绍时域测试并推广其应用,采用了具有时域功能的矢网来对电缆进行具体测试。结合实例介绍了时域功能在电长度测试、电缆性能判定及电缆故障定位等方面的应用,并就时域测试时矢网的参数设置和误差来源进行说明和分析。实验结果表明:用该方法分析电缆时域特性简单方便、结果直观、数据可靠。

基于智能同轴开关系统的联网控制技术应用

同轴转换开关是主备型无线发射系统中不可缺少的设备,是保证安全播出的重要方法和手段。智能同轴开关是一种新型的同轴开关,具有智能参数丰富、衍生功能多等优势和特点。针对多机房、多功能的无线多频道调频电台或多频道电视台集中发射系统,设计智能同轴开关联网控制系统。与现有单一的同轴转换开关比较,本系统具有独特分支拓扑结构,高效的实质节能措施,并采用精确模式识别等技术,提高了控制系统的智能化程度。

生物物质的介电测量技术

本文根据传输线法介电测量原理建立起100KHz～500MHz频率范围的生物物质介电测量系统,该系统由网络分析仪、同轴线腔式传感器及测温控温装置等组成,并由计算机实现自动采样与分析。对测量误差的来源作了详细分析,一定修正和补偿条件下,本文制做的腔式传感器适用于整个频率范围。对人全血和人脑组织等高含水量物质的介电常数测量误差小于3％,电导率误差小于2％。