Attitude Measurement Based On Aerial Gun Camera

Airborne fire control camera gun is a kind of photographic and recording equipment adopted generally on the fighter plane. It is often installed on the airfoil, aircraft nose and cockpit. When fire button is pressed, camera gun takes photos of target alone or together with gun system. The effect of training or combat can be checked by what camera gun shot. At present, traditional film camera gun has been most widely used on the fighter plane. Film camera gun can not satisfy the flight training purpose as a result of some disadvantages of film, such as high-cost, low accuracy and which is hard to save. The image which is collected by camera gun should be interpreted and analyzed when the flight training is finished. There are two kinds of interpretation method by using film camera gun when the flight training is finished. One is empirical interpretation, the other is manual interpretation. Empirical interpretation can work effectively when the shooting distance is short and airman must have rich experience. Compared with the empirical interpretation, manual interpretation is of some accuracy. But this method is complex which need adjust magnification of image and select different interpretation according to different fire kinds.It is necessary to improve the traditional film camera gun and interpretation method with the improvement of army equipment and the progress of training requirements. This paper uses digital equipment to record firing effect. The design which is composed of CMOS imaging sensor using for imaging chip, high capacity FLASH using for data memory and CPLD using for control unit can replace film camera gun. USB data switch is designed in order to transfer data which is collected by digital camera gun to PC. Attitude angle can be calculated by image analysis and specific algorithm. First of all, a series of images preprocessing techniques was taken to extract the precise edge of target image. The four characteristic points of the aircraft are extracted after identifying target profile and the key point can also be obtained. The measurement principles and method of aircraft attitude angle based on a single image plane is researched by using pinhole projection model. Based on the known parameters information of the aircraft and optical systems information, aircraft attitude angle can be obtained through the extraction of linear features and characteristics of the image collected. The error of this method was also analyzed on fixed quantity and nature. The error analysis is a good study to improve system precision to suit for the practical needs.