Research On The Image Acquisition System Based On CMOS Star Sensor

Star sensor is a kind of highly accurate attitude sensor, which has been widely applied in the measurement system of satellite,long-range ballistic missile,and deep space detection. Now normal image sensor of star sensor is CCD, but because traditional CCD star sensor has low integration level, complicated support circuits, multi-voltage power supply and high price, it can not reach the requests of space probe. As the development of CMOS active image sensor, it has become the next object of the star sensor development that the small cubage,low-power,strong anti-interference CMOS image sensor will substitute the CCD to be applied in the image acquisition system of star sensor.The paper aims to develop CMOS star sensor engineering device, and researches the image acquisition system of star sensor. It designs a image acquisition system with SDRAM cache to lower the energy consumption,cubage of image acquisition system and improve the rate of data update. The imagine data from CMOS image sensor is written to SDRAM directly after modulated by CPLD, which is controlled by DSP. The write-operation of SDRAM is started by the output clock of image sensor, and synchronized by the SDRAM main clock. The DSP is informed by CPLD when one-frame image has been acquired. DSP is in charge of initializing CMOS image sensor and SDRAM register, and in normal situation, it controls the whole flow work through the handshake signal with CPLD.The paper designs the hardware and software of image acquisition system of CMOS star sensor, and realizes the functions of synthesis and display of colored images. The image acquisition system has advantages of small cubage, low quality and low-power, and the experiment results show that it can achieve the acquisition of image data.