Hardware Design For Pico-satellite Attitude Determination And Control System

The Pico-satellite is an important research area in modern aerospace technologies. This kind of satellite is famous for highly integrated systems, small size, low weight, low power consumption, short development period, lower expense and strong mobility. The Pico-satellites can construct satellite cluster and simplify the complex task for each satellite to share resource and information with each other. They can be used in three-dimensional imaging, distributed aerospace measuring, scientific experimentation at lower cost. The Pico-satellite will play ever more important role in science research and commercial application with these advantages.The attitude-control-hardware system, realizing attitude determination and control, is an important part of Pico-satellite. The system which is designed in this paper is composed of control subsystem and sensor subsystem. Control subsystem, used to determine current attitude, get the error of it and adjust the attitude by torque, based on low power consumption. All the attitude determination parameters are measured and sent to the control part by sensor subsystem. The goal is to realize the bivectorial attitude determination through the solar vector and earth magnetic field vector. Meanwhile, inertial sensors are used as an important supplement and active magnetic control is the main control way for Pico-satellite. Ultimately, low-power hardware system is designed for satellite attitude determination and control. As the sun sensor used in the satellites are already quite mature, so we focus on control system, magnetometers and inertial sensors design.Hardware design of control subsystem in this paper reduced the power consumption compared to the original one. The single-cycle microcontroller unit is used to realize real time and the speed is 12 times according to usual one. Multi GND layers are set in the system to avoid electromagnetic interference and one-board structure enables the magnetometer to be compact. Controller is used in initial sensor to achieved excellent temperature stability, high power efficiency and the temperature stability is 0.015centigrade. Backup magnetometer systems are used here so that the whole design is more reliable.Thanks to the work of this paper, only half power consumption left in control system and sensor system is achieved here. What's more, 1σnoise of magnetometer is less than micro gauss. Gyroscopes are used as the complement for attitude determination to improve the resolution in special area. Simulation tells us that the design fit the requirement and the whole work is a reference for the coming design.