基于视觉定位的四保阀开启压力自动调节系统

Automatic adjustment system of opening pressure of four-circuit protection valve based on visual localization

针对四回路保护阀开启压力调节存在柔性低、无法精确定位的问题,研制了视觉定位的四保阀开启压力自动调节系统,并提出采用小波半软阈值去噪。通过CCD相机采集四保阀排气口图像,结合图像处理算法,实现排气口圆心坐标的精确定位。利用最小二乘法拟合圆心标定系数,确定排气口中心坐标与伺服拧紧机构运动位移的关系。对测试台的气压传感器进行了精确标定,并通过PID算法控制z轴电机调节开启压力。通过实验证明,该测试装置运行稳定,排气口重复定位精度为0.217 mm,满足现场工业定位精度小于等于0.5 mm的要求。开启压力最大合成标准不确定度为1.76 k Pa,调节成功率达98%,且提高了开启压力的一致性。

As for the problem of low flexibility and imprecise positioning for the opening pressure regulation of four-circuit protective valve,the paper puts forward a system based on visual localization for automatic adjustment of opening pressure of four-circuit protective valve,and proposes the wavelet half-soft threshold denoising. The system uses a CCD camera to acquire the image of exhaust ports of the four-circuit protection valve,achieving the center coordinates of the exhaust ports the precise positioning combined with the image processing algorithms. The least squares method is used to fit the center calibration coefficient,which determines the relationship between the center coordinates of the exhaust ports and the movement of the servo tightening mechanism. The barometric pressure sensors of the test bench are precisely calibrated and the z-axis rotary motor is used to adjust the opening pressure by the PID algorithm. The experimental results show that the system runs stably and satisfies the requirement of the field industry where the repeatability positioning accuracy of each exhaust port of the four circuit protection valve is less than or equal to 0. 5 mm,and the test accuracy reaches0. 217 mm. The maximum standard uncertainty of the opening pressure is 1. 76 k Pa,and the regulation success rate is 98%,which improves the consistency of opening pressure.