数字工业摄像技术用于转轴动态扭矩测量原理的研究

Research on Principle of Saft Dynamic Torque Measurement Based on Digital Industrial Photogrammetry Technology

基于数字散斑相关计算和转动轴表面匹配方法，提出一种利用双相机直接测量转轴动态扭矩的新方法。分别在轴两端使用两个工业相机采集无扭矩时的轴面图像序列，作为参考图像。同步采集扭矩作用下转轴轴面应变图像，对应变图像进行匹配方法，搜索其对应的参考图像，分别对两路应变图像和参考图像进行整像素相关计算、梯度法的亚像素位移计算，得到轴两端扭转角位移，最终计算出轴扭矩。为验证所提方法测量精度，运用Ansys有限元分析软件对轴上扭转位移进行计算，并与所提方法比较，两者结果误差为1．39％，具有较高一致性；进行了不同转速、扭矩下的台架实验，并与标准传感器测量结果比较，两者误差在1．4％～5.3％之间。实验结果表明，数字工业摄像的扭矩测量系统有较高精度，系统结构简单，克服了传统方法安装复杂、信号易受干扰等缺点，适用于转轴动态扭矩测量。

Based on the digital speckle correlation calculation and motion shaft surface matching method, a new method which uses dual cameras to measure dynamic torque of rotating shaft directly is put forward. Two industrial cameras are used to gather shaft surface image sequence which is used as reference images without torque, at both sides. Then surface strain images of rotating shaft under the action of torque are synchronously collected. Motion shaft surface matching method is used to search the corresponding reference images of strain images, and the full-pixel correlation calculation and the sub-pixel displacement calculation of gradient method are performed on two channels of strain and the reference images, respectively. The torsional angular displacement of both ends and the shaft torque are calculated. In order to verify measuring precision of the method, software Ansys is used to calculate torsional displacement of shaft. Compared with the proposed method, the error is 1.39%, which shows high consistency. Bench experiments under different rotational speeds and torque are done, and compared with standard sensor measurements, the error is 1.4%-5.3%. Experimental results show that the torque measurement system based on digital industrial camera has high precision. The system structure is simple, and it overcomes the shortcomings of traditional methods, such as complexed installation, susceptible to interference. It is suitable for dynamic torque measurement of shaft.