Design of Laser Radar Fiber Optic Liquid Level Sensor System

A novel fiber optic liquid level sensor based on laser radar (ladar) is reported here. Using the perfect technique of ladar in which the phase of amplitude modulated light wave reflected from the liquid surface is compared with that of original modulation signal, the distance can be measured precisely. A special symmetric compensating coaxial optical system is proposed to eliminate many adverse effects. It realized the one-time electronic-free optical measurement on a simulated oil tank and achieves an accuracy of 0.3%, within a temperature range of -10 ℃～+40 ℃ over a measuring of 0～10 m.

Application Research on Space Laser Communication in Bistatic Radar System

There exist three synchronizing problems in the bistatic radar system that some signals of the radar receiver must be synchronized with those of the radar transmitter. Several methods realizing data transmission, which are used to complete the synchronization existing in the bistatic radar system, are described. Then a new idea is brought forward that employs space laser communication in the bistatic radar system to realize its data transmission. The theoretic analysis of the idea's usability and its merits are discussed in details. Finally the latest development of space laser communication is introduced, and the utility of the idea is pointed out further.

Design and Tests of A Cable Detection Laser Imaging Radar System

Rotorcraft in low-level flight is endangered by power lines or telephone wires. The development of automation tools that can detect obstacles in the flight path and warn the crew would significantly reduce pilot workload and increase safety. Therefore, a cable detection radar system is developed The real-time dynamic imaging synchronizing with radar space scanning has been implemented in developed ladar system. The requirements of the flight mission to prevent ＂wire strike＂ are analyzed and estimated, the advantages and disadvantages of the millimeter wave system with the laser system are weighted The result shows that Laser system is the best suited for helicopter avoidance obstacle. In addition, several design gist of detecting wire radar that was used in the developed ladar system is proposed and the developed zero backlash imaging technology and several advanced warning function are described. The detailed results of system ground tests and the performances description are presented The ground test of the developed ladar system has demonstrated that the developed imaging ladar system performance can achieve and satisfy the requirements of the mission to prevent ＂wire strike＂.

Dynamic obstacles detection of tram based on laser radar

The detection of obstacles in a dynamic environment is a hot and difficult problem.A method of autonomously detecting obstacles based on laser radar is proposed as a safety auxiliary structure of tram.The nearest neighbor method is used for spatial obstacles clustering from laser radar data.By analyzing the characteristics of obstacles,the types of obstacles are determined by time correlation.Experiments were carried out on the developed unmanned aerial vehicle(UAV),and the experimental results verify the effectiveness of the proposed method.

DETECTION ON MICRO-DOPPLER EFFECT BASED ON LASER COHERENT RADAR

A laser coherent detection system of 1550 nm wavelength was presented, and experimen- tal research on detecting micro-Doppler effect in a dynamic target was developed. In the study, the return signal in the time domain is decomposed into a set of components in different wavelet scales by multi-resolution wavelet analysis, and the components are associated with the vibrational motions in a target. Then micro-Doppler signatures are extracted by applying the reconstruction. During the course of the final data processing frequency analysis and time-frequency analysis are applied to analyze the vibrationM signals and estimate the motion parameters successfully. The experimental results indicate that the system can effectively detect micro-Doppler information in a moving target, and the tiny vibrational signatures also can be acquired effectively by wavelet multi-resolution analy- sis and time-frequency analysis.

Digital Receiver for Laser Imaging Radar

With the extension of the application domains for laser imaging radar, it is necessary to find a new technical way to obtain high technical performance and adaptive ability. In this paper, A new concept of digital receiver of laser imaging radar system is presented. This digital receiver is defined as a time varying parameter receiver which possesses large dynamics region and time domain filter. The receiver’s mode, component structure as well as every function of its processing are described. The results and laboratorial data show the feasibility of digital reception. Also, it can exploit the inherent nature of laser imaging radar to obtain high probability of detection.

High Accuracy and Real-Time Gated Viewing Laser Radar

A gated viewing laser radar has an excellent performance in underwater low light level imaging, and it also provides a viable solution to inhibit backscattering. In this paper, a gated viewing imaging system according to the demand for real-time imaging is presented, and then the simulation is used to analyze the performance of the real-time gated viewing system. The range accuracy performance is limited by the slice number, the width of gate, the delay time step, the initial delay time, as well as the system noise and atmospheric turbulence. The simulation results indicate that the highest range accuracy can be achieved when the system works with the optimal parameters. Finally, how to choose the optimal parameters has been researched.

Building of road boundary map based on laser radar

A method for road boundary detection and tracking using laser ladar with respect to a vehicle＇ s local coordinates is proposed. It can be applied to different types of road conditions, such as roads with or without curbs, having relatively rough road surface and with obstacles on road surface. In the method, some line segments are extracted after a series of preprocessing on range data. The extracted line segments are combined and further selected. They are then united to match the road models and generate the road boundary points which are tracked by Kalman filter. Then the obtained road boundary points are transformed to build a precise vector map by least squares fitting algorithm. These fitted line segments represent road boundary vectors. The vector map is precise enough to provide ample road information such as the orientation of road, the road width and the passable road region. Finally, extensive experiments conducted in urban and semi-urban environment demonstrate the robustness, effectiveness and viability of the proposed method.

Path Planning Approach Based on Dual Laser Radar Fusion

A dual laser radar based path planning method for mobile robot in general outdoor road environment is proposed. Firstly, the point-wise sequence and target library of the global optimal path are generated based on algorithm A*. Secondly, the local target information and the perceptive information from dual laser radar are combined, and the different field information from both horizontal and aslant fixed laser radars is fused. Finally, the optimal driving angle is computed by the improved angle potential field(APF)algorithm. The practical experiment results validate the robustness and timeliness of the proposed approach.

Noise Temperature Characteristics and Gain-control of Avalanche Photodiodes for Laser Radar

Avalanche photodiodes(APDs) are promising light sensors with high quantum efficiency and low noise. It has been extensively used in radiation detection,laser radar and other weak signal detection fields. Unlike other photodiodes,APD is a very sensitive light detector with very high internal gain. The basic theory shows that the gain of APD is related to the temperature. The internal gain fluctuates with the variation of temperature. Investigated was the influence of the variation of the gain induced by the fluctuation of temperature on the output from APD for a very weak laser pulse input in laser radar. An active reverse-biased voltage compensation method is used to stabilize the gain of APD. An APD model is setup to simulate the detection of light pulse signal. The avalanche process,various noises and temperature's effect are all included in the model. Our results show that for the detection of weak light signal such as in laser radar,even a very small fluctuation of temperature could cause a great effect on APD's gain. The results show that the signal-to-noise ratio of the APD's output could be improved effectively with the active gain-control system.

激光雷达测量系统在水库安全检测中的应用

随着科技的不断发展,激光雷达测量系统在水库安全检测中的应用逐渐成为研究和实践的焦点,基于其高精度、高效率的特点,为水库工程的安全性评估和监测提供了重要的技术支持,有望成为水利工程领域的一项创新技术。文章通过对激光雷达测量系统的概述和优势进行阐述,深入探讨了其在水库安全检测中的具体应用。

Doppler shift of a laser pulse beam scattered by a rotating cone and cylinder

Based on laser radar equations, a Doppler shift model of a laser pulse beam scattered by a rotating arbitrary convex target is reported in this paper. The boundary relations between an incident pulse beam and the detected area elements are analyzed by geometric methods. The Doppler shift characteristics of the rotating cone and cylinder are discussed and the difference between the laser pulse beam and the plane wave scattered from the same rotating target is compared accordingly. Numerical simulations show that the Doppler shift is tightly relevant to their dimensions, speeds, and so on. In the same incidence conditions, the pulse beam and plane wave have difference peak values and the same Doppler shift bandwidth. If the waist radius of the pulse beam is larger, the peak value is higher, and the Doppler shifts are proportional to the speed of the rotating target. By virtue of our theoretical model, we probe into the scattered characteristics of the Doppler shifts of a laser pulse beam, which would benefit target identification in national defense.

堤防险情隐患快速巡查系统研究与设计

为提高堤防工程运行安全管理水平,改变传统人工巡查模式,解决堤防巡查效率低下等问题,通过运用激光雷达扫描技术、可见光热红外等传感技术,采用高可靠性无人机载平台搭建空中巡查平台,集成堤防隐患定量化表征、数据实时传输与多算法融合,开发设计高效一致化数据库与可视化及智能交互软件,实现灾害或汛期条件下堤防隐患的快速探测、识别,提高堤防巡查效率。

水下微弱目标双通道激光探测方法研究

在舰船尾流、渔网等微弱目标探测方面,由于目标对探测激光反射回波微弱以及水体背景的强干扰,导致激光探测系统的探测距离近、探测视场小及目标检测能力弱。论文针对近岸浑浊水体激光探测回波信噪比低、目标探测距离近问题,基于积分雷达方程,针对舰船尾流、渔网等微弱目标,仿真研究了激光接收天线长度,轴距对接收能量的影响,设计了激光发射、接收非同轴探测方案,并进行舰船尾流、渔网等目标探测实验,实验结果表明:通过双通道光学接收系统的空间合成,可抑制近程水体强散射的干扰,可实现对激光探测系统大视场接收、光电探测器高灵敏度接收、目标远距离探测的匹配。论文研究成果可为水下激光探测技术工程化提供支持。

小型斜坡隐患识别“空天地”图谱几何遥感方法

“空天地”一体化三查技术体系在西南地区大中型滑坡等灾害早期识别中得到验证和应用,但该方法对人类工程活动诱发的小型灾变体查全率较低。快速准确识别小型隐患点位置极为迫切。本文以广东省龙川县为例,针对点小面广、多发隐蔽的小型斜坡变形和人工切坡建房诱发的崩滑流灾害,研究试验“全查-带扫-点筛-面核-群防-联审”模式的早期识别图谱几何遥感方法,利用2019年1月8日至2022年6月29日94期Sentinel-1雷达影像SBAS-InSAR时序反演、提取异常形变区,综合激光雷达扫描和地质孕灾背景资料从异常形变区图斑中筛查标识出疑似隐患风险点,并开展现场外业核查界定隐患风险类型。结果表明:时序InSAR反演初查发现323处异常形变区,筛查标识出疑似隐患图斑82处,对55处图斑现场外业验证,7处界定为隐患点。证明该方法具有应用价值,能够为地质灾害隐患风险点防灾减灾提供科学依据。

激光雷达信号检测系统的最佳匹配滤波方法

为了解决激光雷达回波信号弱、干扰强问题,提出激光雷达信号检测系统的最佳匹配滤波方法。通过二进小波变换与模极大值分解激光雷达信号检测系统采集回波信号,获取小波系数,保留回波信号特征的同时增加信号输出信噪比,采用匹配滤波处理所获得的小波系数,并经阈值处理后获取小波系数值估计值,利用小波重构估计值得出噪声滤除后信号。实验结果表明:该方法滤波处理后的信号波形均匀、波动幅度小,在不同的尺度因子下,本方法的噪声滤除结果均在80%以上,在固定的尺度因子和噪声输入时,本方法的噪声滤除了82%,检测精度为97.4%,耗时为10.34 ms,均优于其他方法。

基于地形感知的六足机器人运动控制方法

相对于传统的轮式机器人,足式机器人拥有丰富的运动状态,可以适应复杂多变的非结构路面,其中环境检测能力以及稳定的步态控制是现阶段的研究难点之一。结合地形感知与遥控操作的六足机器人运动控制方法采用三维激光雷达实时监测环境,获取机器人周围三维点云数据与高程图信息。提出了基于激光雷达点云数据的自由步态控制算法,实现了遥控器控制机器人运动的功能。在ROS系统中搭建算法,在Gazebo软件中进行步态仿真,最后在真实环境中完成实验验证。为六足机器人在复杂环境中的精确运动提供参考。

基于ROS的变电站室内巡检机器人的研究与设计

为了解决变电站室内人工巡检方式效率低、人工成本高、巡检精度低等问题,更好地促进数字化、智能化电网的发展,本文设计了一套适用于变电站室内巡检作业的机器人系统,该机器人系统包含巡检机器人终端、巡检专网、数据库、远程管理终端四部分,同时对机器人室内定位算法进行了研究,设计了机器人硬件结构,开发了机器人的控制系统,并对机器人的定位准确性、可靠性、安全性进行了模拟仿真实验和现场运行实验。实验结果显示:本文设计的巡检机器人可以很好地适应变电站室内环境,并且该机器人可以实现精确的定位与导航,对变电站室内设备运行情况进行精确巡检与故障预警,满足变电站室内巡检作业要求。最后对本次研究工作进行了总结,并提出了下一步研究计划。

基于二维激光雷达的定日镜清洗车导航避障系统的研究

针对国内外现有塔式太阳能热发电站中存在的无法全自动化清洗定日镜的问题,提出了一种基于二维激光雷达的定日镜清洗车导航避障系统,该系统由清洗车导航系统和激光雷达系统结合而成,利用激光雷达来测量前方定日镜的姿态,从而为清洗车导航系统提供避障保护,以实现清洗车对定日镜的全自动化清洗。首先,建立了地面导航系统坐标系,推导了WGS84坐标系到当地导航系统椭球坐标系的转换方程;其次,分别建立了定日镜、清洗车、激光雷达的运动学模型,并将清洗车和定日镜分别置于多种姿态,截取激光雷达的检测数据,使用检测数据标定激光雷达的安装位置,即激光雷达相对于车辆中心的坐标和安装倾角;最后,对定日镜清洗车导航避障系统进行实际测试,使用标定参数来检测前方定日镜的姿态,实现定日镜的全自动化清洗,当该导航避障系统反馈前方定日镜为异常姿态时,制动清洗车。该导航避障系统还可应用于与自动清洗系统相关的类似应用场景。

新型激光成像雷达图像匹配处理机的设计与实现

激光成像雷达是一种新型成像雷达,图像匹配处理机的使用是该雷达导航应用的先决条件之一。对激光成像雷达的图像匹配处理机进行分析,再进行设计。采用以高速DSP为主处理器,以大规模FPGA为处理器的图像匹配处理机的硬件方案。该方案计算能力强大且可扩展性强,通信接口多样可靠,算法软件实现可灵活修改。实验结果表明,该系统具有高实时性、高数据吞吐率、高可靠性、结构灵活的特点,为激光成像雷达在图像匹配导航中的应用研究提供了强大的处理平台。