A vision-based mechanical vibration measurement method is presented and verified by experiments in this paper. The coded illumination is projected on the objects by a digital light processing projector with a digital micromirror device in it. The projection patterns are designed to be concentric. In one integration time of the camera, the projector is exposed several times, which embeds temporal information in the images. A single frame can be divided into subframes by separating the coded concentric patterns. The centroids of the coded concentric patterns are fitted, and the centroids are treated as virtual feature points with vibration information. The acquisition devices are common low-speed cameras, and they record the vibration whose frequency exceeds the camera frame rate. The temporal resolution is increased by 10 times, corresponding to the 400 Hz sampling frequency in the experiment. We can measure the vibration of multiple points with different sampling frequencies. The frequency measurement accuracy is in the subhertz level in low-frequency measurement, relative error is always slightly greater than 0.01 in high-frequency measurement, and the amplitude resolution is 130 µm.

中文翻译：

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基于单帧编码照明的视觉振动测量

本文提出了一种基于视觉的机械振动测量方法，并通过实验进行了验证。编码照明由带有数字微镜装置的数字光处理投影仪投射到物体上。投影图案设计为同心的。在相机的一次积分时间内，投影仪曝光多次，从而将时间信息嵌入到图像中。通过分离编码的同心图案，可以将单个帧分成子帧。编码的同心图案的质心被拟合，质心被视为具有振动信息的虚拟特征点。采集设备为普通低速相机，记录频率超过相机帧率的振动。时间分辨率提高10倍，对应于实验中的 400 Hz 采样频率。我们可以测量不同采样频率的多个点的振动。低频测量的频率测量精度在亚赫兹级，高频测量的相对误差始终略大于0.01，幅度分辨率为130μm。