Research On Key Technologies Of Automatic Assembly System Of Laser Gyro Dithering-wheel And Resonator

As one of the most important modern navigation instruments, laser gyros have become significant symbols of the level of national optical technology. As the core component of laser gyros, the main body of the vibration system is composed of the resonator and the dithering-wheel, which is mainly assembled by manual method, with disadvantages of high rejection rate, low assembly efficiency and uneven coating adhesive. Therefore, this paper put forward a new peg-in-hole assembly method of large size and high precision based on the micro image mosaicking, and developed an automatic assembly system of the resonator and dithering-wheel.From the features of manual assembly, this paper analyzes the requirements of the automatic assembly system and determined the assembly plan. Then, based on the formulation of the assembly, having finished the design of the layout of system and build of structure, and analyzes the fixture of the resonator parts, the dithering-wheel parts, and the micro vision inspection unit, including control mechanism and related functional mechanism. Meanwhile, the design calculation for resonator’s clamping force and perpendicularity error of the assembly axis is done to guide the parameters controlling in assembly process.As for the micro-vision inspection, take the resonator as an example. Based on the micro-vision closed-loop system, two different step electric platforms are installed in Z series to focus and get a clear image quickly. By using SURF and template matching algorithms, the contour images of the resonator are stitched completely to laying a theoretical foundation for the experimental analysis. The Canny operator is used to extract the full circle after filtering out of the noise by median filter with the integrity of the contour retained. To remove the stitching traces and noise, the ROI template is designed, which limits the area of image processing by logical operation, then use length threshold to screen the outline and improve the processing efficiency. After extracting the contour points, the ellipse is fitted by the least square method, and the contour feature is obtained. In order to uniform the measure in auto-assembly system, the conversion relations between the pulse, the number of pixels and the length of the unit are obtained by calibration.Hardware and software of control system of the auto-assembly system are designed based on the modular design method, which make it convenient for debugging and module developing. Two-level control software was programed with VC++ on PC in order to realize the motion controlling and image processing. Then to find out the best stitching strategy, the comparison experiments between SURF and template matching operator are carried out from the angle of speed and applicability of the algorithm, at the same time, a comparative analysis of partial contour and the complete contour image is established. The results show that the template matching has a better adaptability to the auto-assembly system than the SURF algorithm, and the complete contour has better fitting effect than the partial contour. Finally the resonator and dithering-wheel assembly experiment is carried, the results show that, the auto-assembly system can meet the requirements of assembly concentricity accuracy and the efficiency of which is improved relative to manual assembly.