Design and control of a spherical air-bearing system for multi-d.o.f. ball-joint-like actuators

摘要

This paper presents an analytical investigation of the design method and modeling of an air-bearing system for ball-joint-like actuators. It addresses the method of regulating the three-d.o.f. translations of the rotor introduced by the air-bearing system, thereby improving the dynamic performance of the orientation motion manipulation. The kinematics, which relates the rotor displacement and the air gaps that are essential for design optimization, dynamic simulation and motion control, are derived in closed-form. With a detailed modeling of the pressure-flow relationship as a function of the rotor position, the forces and dynamics of the system are formulated, and design methods for regulating the rotor displacement have been explored analytically. Simulation results suggest that the fluid forces could be generated to passively stabilize the otherwise open-loop, unstable, electromagnetic system. It is expected that this research will be a basis for designing and evaluating an improved VR spherical motor with enhanced torque capability by eliminating mechanical friction.