Active magnetic bearings (AMBs) can actively control the on-board rotor to reduce excessive vibration caused by base motion and improve the system's ability to withstand base excitation. Current active controllers for base motions require additional sensors or complex robust designs, making it difficult to balance reliability and applicability. In this article, a disturbance observer (DOB) approach is developed, numerically and experimentally, to observe and suppress disturbance caused by base motions, which can achieve vibration control without adding additional sensors or replacing the commonly used proportional-integral-derivative controller. Specifically, an AMB-rotor system model considering base motions is established based on general equation of motion. The effect of base motions on the system is considered as disturbance, including additional external forces, stiffness forces, and gyroscopic forces. The working principle, robust stability analysis, and design process of the DOB are presented. Simulation and experiments are conducted on a lab-scale AMB-rotor test rig. The DOB exhibits satisfactory behaviors under harmonic and shock excitations. The impact of the observation bandwidth of the DOB on vibration suppression is also analyzed.

In this paper, a novel configuration of frictionless diamagnetic levitation combined with electrostatic glass motor is presented. A 12.5 mm diameter disc shaped rotor comprised of pyrolytic graphite and glass is fabricated. The rotor disc is levitated stably by the diamagnetic field in five degrees of freedom and driven by the rotating electrostatic field. It is the first time that the combination of both functions is realized. The main advantages of the proposed novel system are noncontact levitation, low energy consumption, and simplicity, which may find promising applications in the fields of spacecraft attitude control (micro gyroscope) or ultrahigh vacuum environment technology (optical trap etc.).

At present, most of the magnetic bearing system adopts the classical proportional–integral–derivative (PID) control strategy. However, the external disturbances, system parameter perturbations, and many other uncertain disturbances result in PID controller difficult to achieve high performance. To solve this problem, a linear active disturbance rejection controller (LADRC) based on active disturbance rejection controller (ADRC) theory was designed for magnetic bearing. According to the actual prototype parameters, the simulation model was built in matlab/simulink. The step and sinusoidal disturbances with PID and LADRC control strategies were simulated and compared. Then, the experiments of step and sinusoidal disturbances were performed. When control parameters are consistent, the experiment showed that the rotor displacement fluctuation decreased by 28.6% using the LADRC than PID control under step disturbances and decreased by around 25.8% under sinusoidal disturbances. When the rotor is running at 24,000 r/min and 27,000 r/min, the displacement of rotor is reduced by around 15% and 13.7%, respectively. Rotate the rotor with step disturbances and sinusoidal disturbances. It can also be seen that LADRC has the advantages of fast response time and good anti-interference. The experiments indicate that the LADRC has better anti-interference performance compared with PID controller.