Optimal motion control of magnetically levitated microrobot

This paper deals with the three-dimensional (3-D) manipulation of a microrobot with levitation technology. A magnetic drive unit is developed to generate the magnetic field for propelling the microrobot in an enclosed environment. The drive unit consists of electromagnets, a disc pole-piece for connecting the magnetic poles, and a soft iron yoke. To handle 3-D high precision motion control of the microrobot, experimental magnetic field measurements coupled with numerical analysis were done to identify the dynamic model of levitation. This approach leads the design of linear quadratic integral (LQI) control system, based on the derived state-space model. The 3-D motion control capability of the LQI control method is verified experimentally, and it was demonstrated that the microrobot can be operated in the levitation system workspace, vertical range of 30 mm and the horizontal range of 20 × 20 mm², with 10 μm resolution.