基于单目视觉和扭摆法原理的刚体转动惯量测量技术研究

Research technology of rigid body moment of inertia based on monocular vision and torsion method

摘要:

在扭振法转动惯量测量中通常忽略系统阻尼对计算结果的影响，从而导致测量误差，针对此问题提出了一种融合视觉检测技术和扭振法基本原理的刚体转动惯量测量方法。该方法通过高帧率的工业相机捕获被测物体的扭振轨迹图像，经过高斯模糊、二值化和Canny边缘算法等处理后提取出图像特征，根据物像坐标转换关系计算每帧图像对应被测物的扭摆角θ，得到扭摆角-时间曲线。由该曲线得到扭振周期T和阻尼比ζ，再根据转动惯量与扭振周期、阻尼比之间的数学模型，最终得到被测刚体的转动惯量值。实验结果表明，该方法能够准确识别扭振阻尼，实现转动惯量的精确测量，在0-5×10-3 kg·m2范围内，单次测量误差的绝对值不超过2.51×10-5 kg·m2，标准差优于1.80×10-5 kg·m2。

Abstract:

In torsional vibration method, the influence of system damping on calculation results is usually neglected, which results in measurement errors. To solve this problem, a rigid body moment of inertia measurement method is proposed, which combines visual inspection technology with the basic principle of torsional vibration method. This method captures the image of torsional vibration track of measured object by industrial camera with high frame rate, extracts image features after processing such as Gauss blurring, binarization and Canny edge algorithm, and calculates the torsional vibration angle θ of each frame image corresponding to the measured object according to object-image coordinate transformation relationship, obtaining the swing angle-time curve. From this curve the torsional vibration period T and damping ratio ζ are obtained.Then according to the mathematical model between moment of inertia, torsional vibration period and damping ratio, the moment of inertia of the tested rigid body is finally obtained. The experimental results show that this method can accurately identify torsional vibration damper and realize accurate measurement of moment of inertia. Absolute error of single measurement does not exceed 2.51×10-5 kg·m2 in the range of 0-5×10-3 kg·m2 with standard deviation better than 1.8×10-5 kg·m2.