Modeling and control of the Eclipse-II motion simulator

The Eclipse-II motion simulator is based on a novel 6-DOF parallel mechanism which realizes 360 degrees free rotations and translations simultaneously. In order for the Eclipse-II to emerge as a full-fledged motion simulator, a robust and effective motion controller is essential. A model-based approach stands out among the various methods of controlling a motion simulator by virtue of its unique benefits such as risk reduction, cost and time savings, and good performance. This paper begins with deriving a physics-based model of an Eclipse-II working sample, whose parameters are estimated using experimental data, with emphasis on friction parameters. After cross-validating the physics-based model, a PID controller augmented with friction-gravity compensation is designed to satisfy design specifications while guaranteeing desired stability margins. In tuning the control gains, the self-exciting oscillation turns out to be major constraints. The proposed dynamic model and control design methodology are extensively used to develop a next-generation motion simulator at Seoul National University in Korea.