Eu:CROPIS: Attitude Control System
The mission Eu:CROPIS (Euglena Combined Regenerative Organic food Production In Space) is an element of DLR’s compact satellite program. The whole satellite is specifically developed to carry a biological experiment. The satellite has a mass of about 230 kg and includes several subsystems which directly interfere with the attitude control system (deployable solar panels, liquid pumps etc.).
The GNC systems department is responsible for development of the complete attitude and orbit control System (AOCS) since phase 0. The goal of the mission is to expose a biological payload to different g-levels (Moon, Mars,...) for six months and to observe the changes in the biological processes. In order to achieve the g-levels, the whole satellite is rotating at constant speed to generate an artificial gravity which cannot be realized in ground-based experiments.
For controlling the motion of the satellite different sensors, actuators and software are needed. The sensors on Eu:CROPIS are magnetometers, Sun sensors, rate gyros and a GPS receiver. The actuation system consists of three magnetic torquers. The control functions are finally realized in software which is running on the on-board computer. The GNC systems department develops algorithms and controllers for all different mission phases. Furthermore, the attitude determination is part of the AOCS. It is implemented with different setups of a Kalman filter.
Finally, the whole AOCS software and hardware is intensively and extensively tested to ensure the mission success. These tests are conducted as pure software simulation and also hardware-in-the-loop tests for which the FACE laboratory will be used.