An Autonomous Microdigital Sun Sensor by a CMOS Imager in Space Application

Digital sun sensors are a category of attitude sensors applied on spacecraft. The proposed microdigital sun sensor (mu DSS) is specifically applied for microsatellites. This application requires low power consumption, high accuracy, and radiation hardness, as well as miniaturization. The mu DSS adopts a low-power windowing readout method: a two-step acquisition-tracking operation. The power consumed in the acquisition mode is significantly reduced with a profiling method which is enabled by a specific pixel design. The high accuracy is achieved by reducing the system thermal noise with a quadruple sampling method. The radiation hardness is strengthened by both hardware design and algorithm correction. The system miniaturization is realized by a SoC solution: integrating the active pixel sensor, timing control circuit, algorithm and processing circuit, and analog-to-digital converter on chip. The proposed mu DSS achieves a 0.01 degrees accuracy with 21 mW at 10 frame/s.