Vision Locating Method Of Engine Block Joint Surface Holes Online Measurement System

The m easurement of holes on en gine cy linder block joint surface is very important, which is d irectly r elated to th e ov erall coup ling ef fect of the eng ine. Considering the problem that traditional locating method by a surface and two pins is not conducive to on-line m easurement, this paper study the engine cylinder block locating method based on vision image. Usi ng area CCD obtain the engine cylinder block pinholes'information, and extracting the pinholes'center by im age processing which estab lish ba seline m easurements f or each test engine cylinder block, and achieve engine cylinder block flexible positioning. The positioning m ethod based on vision image has good stability , moderate accuracy, fast, no n-contact, etc. The m ain research work of this thesis includes:1. Analyzing the status o f the engine cylinder block join t surface holes measurement at home and abroad, the value of this issue is expounded.2. The online m easurement system of holes in engine cylinder block joint surface is in troduced. Studying the visual positioning method base on the p inholes, and estab lish position ing system m athematical m odel. According to the s ite requirements and area CCD ca mera imaging features, pinholes' imaging system and illumination system are designed.3. The calibration m ethod for engine block visual positioning syste m mathematical models is studied. T he ca libration method can qui ckly calculate the parameters of the mathematical model, and the results of calibration can achieve high accuracy which m eet the requ irements of the engine b lock m easurement system'locating. The calibration target is designed and the relate d image processing algoriths are studied.4. The light settings and the related image processing algoriths for engine block holes are studied to solve the problem that the pinholes with cham fer which have an effect on the image edge extraction precision.5. The vision position system was tested on-site and a larege num ber of exprements of repeatab ility we re p erformed in Hubei Shiyan Comm ercial Vehicle Engine Plant of Dong Feng Motor Co, Lt d. The accuracy of the position system can reach±0.020mm. The experiment results show that this positioning system is stable and reliable which can achieve fas t, accurate positioning which make the foundation of engine cylinder's automatic online measurement.