5-degrees of freedom active control AMB Active Magnetic Bearing Condition Monitoring History of engineering & technology Internet of Things IoT active magnetic bearing active magnetic bearings axial gap compliant actuation component benchmarking cost reduction damping design refinement double stator structure electrodynamic electrodynamic bearing energy efficiency fatigue testing fiber reinforced plastic kinetic energy storage magnetic spring modeling optimal design parallel elastic actuators (PEA) passive levitation passive magnetic bearing pediatric performance criteria