基于激光测距的三维空间景深获取

发布时间：2018-01-04 22:36

本文关键词：基于激光测距的三维空间景深获取　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：激光扫描测距技术采用非接触式主动测量的方式直接获取目标的三维数据,克服了传统测量技术的局限性,具有测量速度快、精度高、抗干扰能力强、适用范围广、不需要合作目标等优点,是实现三维测量最重要的技术手段。目前激光扫描系统普遍存在体积大、功耗高、扫描速率慢等问题。MEMS振镜技术为其向小型化、低功耗、低成本和便携式应用的方向发展提供了相应的器件,具有重要的研究意义。本文将静电式MEMS振镜应用到三维扫描测距系统中,静电式振镜具有结构简单、扫描频率高、功耗低、体积小等特点,是三维扫描系统小型化的首选。本文以静电式MEMS振镜作为扫描器件,设计了一种高速激光扫描测距系统,并进行了实际测量和数据分析,为三维激光扫描技术的小型化取得了突破。针对激光扫描测距系统设计时四个关键环节,详细分析和比较了目前主流的激光测距方法、激光测距探测方法、激光扫描方法和时刻鉴别方法。针对小型化、高扫描速率的特点,设计了整个激光扫描测量系统。系统选择使用脉冲激光测距法来测距,脉冲激光器发射脉冲激光后,一部分经分光镜反射直接由PIN探测器接收作为start信号。利用MEMS振镜作为扫描器件对另一部分脉冲激光反射以调整飞行方向,脉冲激光到达探测目标后发生漫反射,采用单元APD探测器接收回波信号,并用前沿时刻鉴别法确定时刻作为stop信号,再由计时模块测量两个信号的时差。采用台湾OPUS公司的静电式MEMS振镜OP-6111作为扫描器件。分析了其工作原理和扫描轨迹的特点,通过仿真确定了工作频率,根据性能参数开发了配套的驱动电路,实现了振镜驱动和坐标计算。并在此基础上开发了激光投影系统,实现了“SEU”字符的投影显示。本文基于德国ACAM公司的时差测量芯片TDC-GP21设计了脉冲激光测距系统。时差测量的精度可以达到91.5ps。实际测距时,使用固体激光器产生脉宽35ns的脉冲激光,使用PIN探测器和APD探测器给TDC-GP21芯片提供start和stop信号。测量近距离目标时,误差小于0.23m。最后本文基于MEMS振镜扫描模块和脉冲激光测距模块,搭建了激光扫描测距系统。使用RS232串口将数据实时传输到电脑,测量速率达到2333Hz。本文对系统的测量速率和扫描盲点问题进行了详细的分析,提出了改进方法。用系统对简单物体进行三维扫描,用MATLAB还原出了三维图。
[Abstract]:Laser scanning ranging technology directly acquires 3D data of target by non-contact active measurement, which overcomes the limitation of traditional measurement technology, and has high measuring speed, high precision and strong anti-interference ability. It is the most important technique to realize 3D measurement because of its wide application range and no need of cooperative target. At present, the laser scanning system is widely used in large volume and high power consumption. MEMS vibroscope technology provides devices for miniaturization, low power consumption, low cost and portable applications. In this paper, electrostatic MEMS vibroscope is applied to 3D scanning ranging system. Electrostatic vibrating mirror has the characteristics of simple structure, high scanning frequency, low power consumption and small volume. It is the first choice for the miniaturization of 3D scanning system. In this paper, a high speed laser scanning ranging system is designed with electrostatic MEMS vibrating mirror as the scanner, and the actual measurement and data analysis are carried out. A breakthrough has been made for the miniaturization of 3D laser scanning technology. Aiming at the four key links in the design of laser scanning ranging system, the current mainstream laser ranging methods and laser ranging detection methods are analyzed and compared in detail. Aiming at the characteristics of miniaturization and high scanning rate, the whole laser scanning measurement system is designed. The system chooses the pulse laser ranging method to measure the distance. The pulse laser emits the pulse laser. One part is directly received by the PIN detector as the start signal, and the other part of the pulse laser is reflected by the MEMS vibrator as the scanner to adjust the flight direction. When the pulse laser reaches the target, diffuse reflection occurs. The unit APD detector is used to receive the echo signal, and the forward time discriminant method is used to determine the time as the stop signal. Then the time-difference between the two signals is measured by the timing module. The electrostatic MEMS vibrating mirror OP-6111 of Taiwan OPUS Company is used as the scanner. The working principle and the characteristics of the scanning track are analyzed. The working frequency is determined by simulation, the matching driving circuit is developed according to the performance parameters, the drive of the vibrating mirror and the coordinate calculation are realized. On this basis, the laser projection system is developed. Implemented "SEU" In this paper, the pulse laser ranging system is designed based on the TDC-GP21 chip of ACAM company in Germany. The precision of time difference measurement can reach 91.5 ps. . A pulsed laser with a pulse width of 35 ns is generated using a solid-state laser. PIN detector and APD detector are used to provide start and stop signals to TDC-GP21 chip. The error is less than 0.23m.Finally, based on the scanning module of MEMS vibroscope and the module of pulse laser ranging, a laser scanning ranging system is built, and the data is transmitted to the computer in real time by using RS232 serial port. The measurement rate is 2333Hz. This paper analyzes the measurement rate and the blind spot of the system in detail, and puts forward an improved method. The system is used to scan the simple object in three dimensions. The three-dimensional image is restored by MATLAB.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN247

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