| Monocular pose measurement technic has a great value in helmet-mounted display and sight system.To improve the accuracy of monocular pose measurement for helmet,the precise 3D coordinates of spatial points on the surface of helmet are needed.Imitating the processing of monocular pose measurement and aiming at higher accuracy in feature points extraction and coordinates measurement,an all-around coordinates measuring system with single camera and a two-dimensional turntable is proposed.As feature points rotating with a two-dimensional turntable,the CCD camera is able to take pictures of feature points from different views.By the principle of relative motion,the single-CCD sensor model was imaged as a visual multi-CCD sensor model.Therefore,to get the intersection of the perspective projection lines is to obtain the space coordinates.In the paper,the principle and model of multi-angle monocular coordinates measuring system is presented and the shaft and its calibration methods are described in detail.The experimental result shows that the system based on the virtual multi-CCD sensor model can achieve the standard deviation of 0.019 mm,and thus proves the feasibility of its multi-angle coordinates measurement for spatial points.Main work is as follows:(1)Analyzing the status of coordinate measuring machines(CMMS)and vision coordinates measurement method at home and abroad on the subject of the research value.(2)This paper expounds the principle of the monocular multi-angle coordinates measuring method,builds the monocular multi-angle model and its calibration methods are described in detail.What’s more,errors may occur in the system are analyzed.(3)The measuring system is built in the hardware and software parts.First,a stereo calibration target with infrared LEDs as feature points is built and a calibration method with higher precision for two-dimensional turntable is proposed.Flow charts and design thought of main program and each module are presented in software design part.(4)In the end,the experimental system is set up.The external parameters calibration experiment is carried on and based on it,some simulation tests are done to prove the correctness of the method.The repeated tests are carried on in different angles.It is verified that the standard repeatability deviation of coordinates measuring system is 0.019 mm. |
