Drag-Free Attitude Control System Modelling in the LISA Pathfinder Operational Simulator
- Paper number
IAC-09.C1.6.3
- Author
Mr. Dag Evensberget, VEGA Deutschland GmbH & Co, KG, Germany
- Year
2009
- Abstract
LISA Pathfinder is one of several missions under development, for which Drag-Free Attitude Control Systems (DFACS) enable extremely precise spacecraft control. DFACS let spacecraft follow geodetic trajectories by compensating all non-gravitational forces and torques. This paper describes the design and implementation of the DFACS in the LISA Pathfinder Operational Simulator. Operational simulators exist to verify flight procedures, and partly to verify the correctness of the real spacecraft On-Board Software (OBSW). The real OBSW is run inside an emulator of the on-board computer. It is known that in traditional open-loop control of spacecraft, the accuracy requirements in AOCS modelling for an operational simulator are not severe. When a DFACS system is active, however, the OBSW and the AOCS are operating in a closed loop: In order to validate the OBSW DFACS algorithms, it is therefore desirable that the OBSW cannot distinguish the simulated environment from the real spacecraft environment. Thus, AOCS and Payload components that are part of the closed control loop should be accurately modelled. A new simulator model is presented. It provides sufficient accuracy and smoothness that the DFACS system may function continuously, produce reasonable actuator commands, and not trigger any undue FDIR action from the OBSW. The model is tightly integrated with the existing orbital environment library PEM and the existing dynamics library SIMDYN.
- Abstract document
- Manuscript document
(absent)