Research Of Sensors For Pico-Satellite Attitude Determination System

Pico-satellite attitude determination system has its own particularity for it is totally different from traditional satellite. The objects of the paper center on the analog sun sensor, digital sun sensor and three-axis magnetometer applied to pico-satellite.In order to meet the requirement of more accurate, lower power consumption and smaller volume, the principles of the sensors are analyzed in depth and the existing designs are optimized and improved.The digital sun sensor, based on panoramic annular lens, has a large feild of 120°x 180°and the high accuracy of 0.02°. The power consumption is primarily put emphasis on during the design of hardware and software. As a result, the maximum power consumption for the whole system reaches as low as 250mW/3.3V for the duration of one frame time. The volume of the whole system is 50mm x 40mm x 40mm, greatly improving system integration and reliability. In addition, another solution is proposed for providing a contrast sample.According to the deficiencies such as low accuracy and integration of the analog sun sensor in ZDPS-1A, the new sensor device with high performance is applied and the design of circuit for signal processing is optimized to minimize the volume and improve the measurement accuracy. By analyzing of the characteristics of the optical front end, the theoretical model is established to provide a reference for circuit design. By analyzing of the error of the system structure, the establishment of a structural model for machining provides the corresponding requirements. The circuit errors. noise and temperature drift are also taken into account. As a result, the power consumption of analog sun sensor is as low as 33mW, with the angle measurement accuracy of 1.21°. significantly enhancing the system reliability.For the shortcoming of the backup three-axis magnetometer in ZDPS-1A such as low accuracy, low integration and high power consumption, the important factors, such as the bridge offset voltage compensation, the output magnetic field calibration, voltage crosstalk and temperature compensation, are analyzed. Furthermore, the the error model of structure is established to improve the accuracy. As a result, the system noise is 10-2 mGuass and the measurement accuracy reaches as low as 0.9mGuass. In addition, another solution with lower consumption and smaller volume is proposed for providing a good reference.The sensors achieve the requirements of low power consumption and high accuracy, providing the foundation for the next generation of pico-satellite.