Research On The Application Of Vision Positioning Technique In The Measurement Of Inertial Parts

Gyroscope is a very important sensitive components, which is used in navigation and control system in ships, aircr aft and missiles. The inertial parts in th e gyroscope usually contain precise struct ures, such as deep holes and s mall bearings. Accurate positioning should be done before m easuring these precis e s tructures o n CMM(Coordinate Measuring Machine).In this ar ticle, we us e vision p ositioning techniques to develop a vision positioning system for the inertial parts, which is built on the DHFORM series CMM in our lab. The system can provide rapid and accurate non-contact positioning, which ensures that the measuring goes successfully and improves the measuring efficiency.The main research works of this article are listed as follows.1) Positioning m issions are m ade firs tly b y analyzing the s tructure and geometrical elements of two of the m ajor inertial parts and the coordinate m easuring machine. Basing on the missions, the vision positioning system are designed and built. For the inner fram e part, special fix ture is designed. Back lighting is used to project its contour. Long focal length and unfocus ed lighting is used, which reduces the special occupation of the sy stem. T elecentric lens is used, which can av oid perspective and im prove the precision. For the outer frame bearing part, fixture and lens are integrated into one to keep the hole in the field of cam era view. And back circle light source is design for the ruby bear ing in the part to achieve pictures with high contrast.2) In the fields of i mage denoising, image segmentation, image edge detection, edge contour extraction and edge subpixel localization, the usual im age processing algorithms are an alyzed and com pared in experim ents. Basi ng on the results of experiments, proper algorithm s are selected to be used in th e vision positioning system.3) Positioning programs and methods are designed for the specific parts. For the vision positioning system of the inner frame part, methods are designed to demarcate the angle between the o ptical axis and X axis of CMM and to build the rela tionship between image coordinate and CMM coordina te. And methods of the positioning of inner frame part are designed and tested. Basing on the re sults of experim ents, the unstable positioning items are analyzed and improved by changing m ethod. For the vision positioning system of the outer fram e bearing part, demarcation is also m ade. And the programs of positioning are designed basing on the features of the image of the part. Experiments show that the accuracy of positioning fulfills the missions.