基于ARM的互相关红外测速系统研究

发布时间：2018-01-17 00:02

本文关键词：基于ARM的互相关红外测速系统研究　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：红外测速光幕靶在测量弹丸速度领域具有重要的地位,高精度测时方法是该领域研究的主要方向之一。目前在该类系统中采用最多的是脉冲计数法实现测时,但速度较高的弹丸往往会产生弹头波等激波,使测时精度大大降低,为了解决上述问题,本文设计了基于互相关测时的实时测速系统。在传统互相关算法和广义互相关算法的研究基础上,建立了互相关测时的MATLAB仿真模型;通过仿真模拟脉冲计数法测时、传统互相关和广义互相关测时,证实了互相关算法在测时方面具有更高的精度,且具有平滑噪声的作用,能减少噪声和其他干扰对测时的影响。快速傅里叶变换FFT完成互相关测时可以使运算量大大减少,适合实时测量系统的应用。设计的测时模块结合CPLD的硬件测时模块和互相关算法测时分析,CPLD测时控制AD采集时间长度和参与互相关运算的离散信号序列长度。在互相关算法测时分析时采用二次搜索峰值的方法和三点插值拟合函数的方法确定渡越时间,二次搜索峰值的方法可以减少搜索峰值的次数,提高运算速度;三点插值拟合有利于提高测时精度。采用ARM芯片设计的AD采集模块经多次数据采集,AD转换精度满足系统要求,且节省了开发时间和费用,并且使用带有浮点运算的处理器具有更短的运算时间。最后通过设计对比试验的方式,验证了该系统的可行性,在测速范围内具有较高精度,满足各项指标的要求。
[Abstract]:Infrared velocimetry screen target plays an important role in the field of projectile velocity measurement. High precision time measurement method is one of the main research directions in this field. At present, pulse counting method is widely used in this kind of system. However, projectiles with high speed often produce shock waves such as warhead waves, which greatly reduce the precision of time measurement. In order to solve the above problems. In this paper, a real-time velocity measurement system based on cross-correlation time is designed. Based on the research of traditional cross-correlation algorithm and generalized cross-correlation algorithm, the MATLAB simulation model of cross-correlation time is established. By simulating the pulse counting method, the traditional cross-correlation and generalized cross-correlation are used to verify that the cross-correlation algorithm has higher accuracy and smoother noise. It can reduce the influence of noise and other interference on the time measurement. The fast Fourier transform (FFT) can reduce the computation greatly when it completes the cross-correlation test. It is suitable for the application of real time measurement system. The designed time measuring module is combined with the hardware time measurement module of CPLD and the time measurement analysis of cross correlation algorithm. The length of AD acquisition time and the length of discrete signal sequence involved in cross-correlation operation are controlled by CPLD. The method of quadratic searching peak value and the method of three-point interpolation fitting function are used in the time measurement analysis of cross-correlation algorithm. Transit time. The method of second searching peak value can reduce the times of searching peak value and improve the operation speed. Three-point interpolation fitting is helpful to improve the precision of measuring time. The AD acquisition module designed by ARM chip can meet the system requirements by multiple data acquisition and AD conversion accuracy, and saves the development time and cost. And the processor with floating-point operation has shorter operation time. Finally, the feasibility of the system is verified by designing a comparative test, which has a high accuracy in the range of speed measurement. Meet the requirements of each target.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN216

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