My Project is based en two very different parts. The first part is that I am the designer of the sensors’ net that is in charge of controlling the general satellite status. The second one is the attitude control that means the stabilization and positioning of the satellite.
The sensors that will be used are as follows: an Earth sensor, a temperature sensor and attitude sensors (an accelerometer and a gyroscope). The position sensors as much as the Sun and Earth sensors will serve us for knowing the satellite position regarding to the Earth or, if we have a camera as a payload, we’ll know what is going to be photographed.
Temperature sensors will be distributed by all the elements that constitute the satellite: solar panels, batteries, internal circuitry, etc… in order to know all time their actual status and, if necessary, detect which one is failing. To control the attitude, I am combining two systems: the radiometric spin and the terrestrial magnetic field stabilization. Both systems have great advantages as the fact they are passive ones (with minimum current charge) and the ones giving best results in similar satellites.
The radiometric spin will serve us for attenuating the structural torque produced by too much nutation and, at the same time, for getting a more uniform distribution of hot. The Earth magnetic field stabilization system will be used to align the satellite with the Earth magnetic field in such a way that the satellite when flying in a polar orbit could point its antennas to the Earth and communicate with the base station.
The first pass, and one of the most important I have given in my project, has been to get well acquainted with the aerospace and physical concepts that will show to me the way to be followed next. Now that these first concepts are quite clear, I will investigate the different control systems available that would be able to control the attitude and, at the time of the evaluation of all of them, to be able to select the ones that would comply better with all specifications and will have enough viability. These systems are the radiometric spin and the Earth magnetic field stabilization.
The next pass I did was to start an extended study about all the sensors needed to determine the satellite position regarding to the Earth and which of them would be the most adapted to our necessities. The ones selected were a Sun sensor, an Earth sensor, a gyroscope and an accelerometer.From the very first beginning we thought to include a GPS in it, but finally it was discarded because with the sensors previously mentioned before, we’ll already have the attitude and pointing of the satellite quite well controlled.
At the present time, I had already a clear view of the global project. There are to working lines to be done: the attitude and the sensors. In respect to the sensors net, I have been looking for suppliers and their specifications in order to select the best well adapted to LEO orbits. Now, we have to decide a supplier and start working in the hardware we’ll buy.
The attitude is the working line that needs more study and planning, because if we start with a very small error, that could be a critical one. That’s why I am carefully studying more carefully the elements needed for a LEO orbiting satellite and their real importance in a simulation. The next pass will be a simulation of the satellite motion and a calculation of the physical parameters of the material needed.
Satellite segment
