Attitude Determination Experiment
The student team from Delft University of Technology (TU Delft), The Netherlands, developed a technology demonstration experiment, the ESEO Attitude Determination Experiment (ADE). The ADE consists of a software capable of estimating the attitude (orientation) of the satellite by four different algorithms running in parallel having as inputs the data provided by the satellite attitude sensors.
Attitude Determination Experiment (ADE), Delft University of Technology (TU Delft), Netherlands
The ADE has been programmed in the C-language and adjusted for the RTEMS real-time operating system. All operations to be performed by the software have been verified to operate within the assigned budgets and limitations of the hardware on board the satellite. The software is capable of running the four algorithms within 100 milliseconds while retaining a code size 24 kB, which is lower than the 35 kB budget and a memory size of 8.8 kB, which is lower than the 10 kB budget.
All algorithms have undergone extensive Monte-Carlo simulations to test for stability and sensitivity to the involved parameters. All algorithms manage to retain a steady-state angular estimation error lower than 0.5 degrees under conditions varying by about 30% from the expected parameters.
The ADE payload will test four algorithms/filters in satellite attitude estimation. Different filters have different characteristics that translate to either benefits or detriments. It is rare for any spacecraft to estimate the attitude using more than one method at the same time. Therefore, it is difficult to test the performances of different types of filters in tandem, using the same conditions, outside of a purely theoretical and simulated environment. The ESEO mission thus provides a good opportunity for, first, testing filter performances outside of the laboratory environment under real conditions. Secondly it allows the results of different filters, using the same measurements, to be compared. The four filters have been selected based on their different characteristics, such that no filter is of the same type. This is considered to create the greatest scientific value. If significant differences exist between filter types, they will become apparent from this experiment.
HIGHLIGHTS: The ESEO Attitude Determination Experiment (ADE) will be able to compare for the first time the performances of different attitude estimators working in parallel and receiving at their inputs the same data from the attitude sensors of the satellite during its mission.