For ultra-precision, large stroke, and high start/stop acceleration, a novel magnetic suspension platform with three types of magnetic bearings is proposed. The structure and working principle of the novel platform are introduced. The passive magnetic bearings are used to compensate for the weight of the actuator. The repulsive force of the passive magnetic bearing model is established and analyzed. The Lorentz force-type magnetic bearings are used to provide driving force and rotational torque in the XY-plane. The driving force model and rotational torque model are established. The electromagnetic suspension bearing is used to provide driving force in the Z-axis and rotational torque along the X-axis and Y-axis. A novel Halbach magnetic array is designed to improve the magnetic flux density in the air gap. The finite element method is used to validate the force model, torque model, and magnetic flux density in the air gap. The results show that the maximum force of the passive magnetic bearing is 79 N, and the rotational torque stiffness is 35 N/A in the XY-plane and 78 N/A along the Z-axis. The driving force stiffness is 91 N/A in the XY-plane and 45 N/A along Z-axis.

No abstract

Compared with traditional liquid crystal and organic light emitting diode (OLED), micro light emitting diode (μLED) has advantages in brightness, power consumption, and response speed. It has important applications in microelectronics, micro-electro-mechanical systems, biomedicine, and sensor systems. μLED massive transfer method plays an important role in these applications. However, the existing μLED massive transfer method is faced with the problem of low yield. To better transfer the μLED, the force value detached from the substrate needs to be measured. Atomic force microscope (AFM) was used to measure the force of a single μLED when it detached from the substrate. The μLED was glued to the front of the cantilever. When a single μLED was in contact with or detached from the Polydimethylsiloxane (PDMS), the maximum pull-off force can be obtained. The force at different peel speeds and preload was measured, and the experimental results show that the separation force between a single μLED and PDMS substrate is not only related to the peel speeds, but also related to the preload. The force values under different peel speeds and preload were measured to lay a theoretical foundation for better design of μLED massive transfer system.

To improve the control accuracy and output torque of magnetic suspend and control gyroscope, a Lorentz magnetic bearing with double second auxiliary air gap is proposed, and its mechanical structure is introduced. Frist, the structure and working principle of the Lorentz magnetic bearing with second air gap is introduced and the magnetic circuit model of the magnetic bearing is established by the equivalent magnetic circuit method. Second, on the basis of the circuit model, the maximum magnetic flux density of the winding area is analysed by finite element method. The fluctuation rate of magnetic flux density in winding area with double air gap scheme is 5.9%, and the maximum magnetic flux intensity at the winding coil can reach 0.462T. Finally, a bearing prototype is made, the theoretical calculation and finite element simulation results are verified by experiments.