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分析了琴弦的亥姆霍兹运动,设计了一个基于高速摄影的非接触式光学测量系统,用于测量真实小提琴上琴弦的振动。通过特殊的光路设计和在琴弦上设置标定点,以7 000frame/s的速度和336×480的图像分辨率拍摄了拉弦和拨弦时琴弦上标定点的三维振动形态。采用圆形霍夫变换图像处理算法、奇异值分解算法和自动批处理,对记录的大量序列图像进行处理,提取了弦振动的位移和轨迹等数据。实验结果表明,该测量系统能够精确跟踪小提琴琴弦的振动状态和包络轨迹,振动位移曲线的图像处理精确度达到0.03mm。该系统为进一步研究提琴琴弦的振动机理和建立精确的琴弦振动理论模型提供了一种有效的实验方法。
The Helmholtz movement of the strings was analyzed and a non-contact optical measurement system based on high-speed photography was designed to measure the vibration of the strings on a real violin. Through special optical path design and setting calibration points on the strings, the three-dimensional vibration patterns of the calibration points on the strings at the string pulling and the string picking are recorded at the speed of 7 000frame / s and the image resolution of 336 × 480. A circular Huff transform image processing algorithm, a singular value decomposition algorithm and an automatic batch processing are adopted to process a large number of recorded sequence images and extract displacement and trajectory data of the string vibration. The experimental results show that the measurement system can accurately track the vibration state and envelope trajectory of the violin strings, and the image processing accuracy of the vibration displacement curve reaches 0.03 mm. The system provides an effective experimental method for further studying the vibration mechanism of violin strings and establishing a precise theoretical model of string vibration.