Performance Of A Six Degree-Of-Freedom Precision Pointing Test Rig Using Slotless Self-Bearing Motors

The slotless self-bearing motor (SBM) technology is first utilized to fully provide bearing and motoring functionality simultaneously in a six degree-of-freedom (DOF) prototype gimbal system, to demonstrate its precision pointing and smooth angular slewing capability. The novel six DOF magnetic actuator incorporates two SBMs to produce both radial bearing forces and motoring torque and one conventional thrust active magnetic bearing (AMB) to provide axial support. The dynamic model of the system is developed and a set of six decoupled PID controllers is designed based on the theoretical model. The closed loop performance of the system confirms experimentally that these controllers provide stable levitation and smooth angular slewing. The most encouraging result is that the actuator is capable of pointing down to less than 377 nrad angularly.