Attitude control of a tilted air spindle testbed using proof mass actuators

The attitude dynamics of an air spindle and platform testbed, controlled by two proof mass actuators fixed to the platform, are studied assuming that the air spindle is not exactly vertical. A tilt angle of the air spindle induces a gravity moment that has a long term effect on the rotational dynamics. A mathematical model is used to study the free dynamics with the proof masses fixed, as a basis for parameter identification and to explain the longer term dynamics that have been observed in experiments. Feedback compensation for these gravity effects is discussed.