Rotation Angle Measurement, Machine Vision-based Helmet Display

In this thesis, the machine vision theory and method were adopted in measuring the turning angle of HMS(Helmet Mounted Sight) wearing on the head of pilot. Considering the distance between helmet and the top of the cabin is almost invariable and the head move slightly, So firstly, the monocular method is proposed to measure the azimuth angle and the look down and up angle. In order to improve the adaptability of monocular way, the stereo vision method was researched on the basis of monocular way. In this method, two camera cameras were placed in a certain distance and a certain angle, the two cameras work together to achieve pairs of images , then the images were analyzed and processed, then the useful data were got and computed and finally get turning angle.The two methods above both need a standard characteristic plane flatly placed on the top of the head, there is a circle in the plane and red, green and blue LEDs are placed on the circumference, the three LEDs are at intervals of 120 degrees.In monocular measurement, The camera is fixed in the cabin and in a certain distance from the top of the head(about 15cm-20cm considering the space in the cabin ) and right on the above of the head. The camera photographs downwards perpendicularly and the optical axes go through the centre of the circle. The camera continuously photographs the characteristic plane with the head turning and then extract the characteristics of images to analyze and process, and the necessary parameters were acquired on the basis of geometrical relation of characteristics and finally the angle value is computed. In stereo vision measurement, camera calibration is done firstly, then extract characteristics and three-dimensional matching is done in order to construct three-dimensional information of the research object and in the end ,the angle value is achieved.The measuring method above is experimented in lab and has got preconcerted result, It offered a easy and feasible means to measure the orientation line of sight of HMS in the precondition that no weight is added to the helmet. In this thesis, the method is only proposed and implemented in the lab so it need further research.