Research On Gear Vision Measurement Technology Of Adapting To Light Intensity Change

Gear mechanism is one of the most widely used mechanisms in mechanical transmission. For the gear is complex in shape and has many precision projects, detection is difficult and the research focus in the field of manufacturing industry. The existing gear precision measuring instrument mainly based on the contact measurement is complex in operation and low in detection efficiency. Especially for small module gear, it is difficult to detect for the contact measurement affected by the size and shape of the measuring head.The vision measurement technology has the advantages of non-contact type, high precision, high speed, real time and online measurement. The small module involute spur gear is taken as the research object and its vision measurement technology is studied in this paper. The main research contents and results are as follows:A gear vision measurement system which includes two parts of image acquisition system and image processing system has been set up. The image acquisition system uses the way of back light illumination and takes CCD image sensor as the core imaging device. Containing three steps of image processing, feature extraction and project measurement, the image measurement algorithm of pitch precision is designed. Based on the algorithm, the image processing system is developed by the joint programming approach of C# and HALCON.Image processing is the core part of the vision measurement. It has achieved good results to suppress noise by the method of Gaussian filter for gear image. After extracting the region of interest in the image, image segmentation is firstly carried out, and then the connected region is extracted by 8-connectivity method, so that the number of teeth can be obtained accurately. Aiming at the problem that the traditional edge detection methods are easy to be affected by light intensity change, a method of dynamic threshold of adapting to light intensity change is presented. The method extracts edges by subpixel-precise thresholding algorithm and uses the average gray of region to characterize the change of light intensity. By means of the relationship between the edge and the average gray of region, the edge and the threshold, the relationship between the threshold and the average gray of region is derived, which can compensate the effects of the light intensity change on the measurement results.Finally, the precision of the measurement results of the system is verified by three coordinate measuring machine. Moreover, the experiment of light intensity change is designed, and the results show that the method of adapting to light intensity change can ensure the stability of the measurement results.The research of gear vision measurement technology and the method of adapting to light intensity change which is presented in the paper have important theoretical significance and application value.