The Control Strategy Research Of Main Control System On Space Camera

With the rapid development of modern science and technology, there are higher requirements on the quality of the space camera remote sensing image. To satisfy the demands of high resolution and wide field, it makes focal length longer, more volume, more number of CCD and information content. For the main control system of a camera, the data processing and control becomes more complicated.Due to low resolution of most space cameras in our country, the method of the main control system is simple. The telemetry data downloaded from the satellite to the ground control center is usually manually interpreted. The status of space camera is checked according to the interpretation result, and then the remote control command is sent by the ground control center to monitor the space camera to complete image work, which costs quite many human resources. Because of the development and requirements of high resolution and wide field of the space camera, the amount of data grows, and the control becomes more complicated, which lead to the risk of false positive and false negative by the traditional manual method. Meanwhile, in the case of a breakdown during working time in orbit which can‘t be handled timely and efficiently, the space camera can only work with malfunction, bringing hidden deadly danger to local or even the whole device. As a result, it is necessary to carry out research on the control strategy of main control system on space cameras. It means that by finishing regular work, the main control system can have independent processing function simultaneously to improve system reliability.This paper researches the technological developments of space cameras both at home and abroad, and the application status of automatic control technology in space cameras control fields. Combined with a project for a particular type high-resolution off-axis camera in research, according to the operating characteristics of the control system on space camera, this paper launches technical research related to the control strategy. The main content of the paper is as follows:The main functions of control system on space cameras and the primary mission in orbit are analyzed; the data transmission protocol format between the control system and subsystem as well as the satellite is designed, so as to lay the foundation for achieving the control strategy of main control system on space cameras.Because of increasing amount of data onto space cameras, to satisfy the real-time requirements in orbit, the telemetry data processing method based on discrete Hopfield neural network is proposed, and its algorithm is improved. With the associative memory ability of discrete Hopfield neural network, the telemetry data is decided to be normal or not; then the failure level according to the result is ranked and the neural unit according to failure level is dynamically regulated by the main control system. Therefore, the period of communication is shortened and the processing speed of data analysis is enhanced.To improve the reliability of space cameras and have the autonomous control ability, the remote control command processing method based on hierarchical intelligent control is proposed. Firstly, the failure level of telemetry data is recognized; then the faulty unit is specifically segregated, monitored or recovered according to the remote control command. It enhances the rapid response capacity of space cameras and improves device‘s security.To simplify the design process, the hardware circuit modular design of main control system on space cameras is carried out. For reusing circuits, the single board design cycle is shortened.Experiments test the control strategy of main control system. As the experimental result shows, with the strategy mentioned in this paper, the burden of manual interpretation is relieved; the accuracy of telemetry data analysis is improved; more importantly, failure isolation and recovery can be individually conducted according to the interpretation result so that the space camera can keep stable and reliable in orbit. It guarantees the camera to finish image task successfully. The time of standby operation is 50 ms, the time of proper functioning is 150 ms, the performance period is short, and processing speed is fast. It has practical significance and application value.