Abstract: The multi-degree-of-freedom spherical driving joint is direct supported and driven by spherical motor owns high mechanical integrity and has advantages on control and trajectory planning. But due to the friction of mechanical bearing which will generate heat, it has bad dynamic characteristics of the driving joint when it works at high speed and even ultra-high-speed. Based on motor technology, magnetic levitation and robotics, a novel multi-degree-of-freedom spherical reluctance driving joint with magnetic levitation is presented, and the coupling model of its electromagnetic suspension force and electromagnetic torque is established. Meanwhile, the joint rotor’s non-linear strong coupling three dimensional dynamical model and inverse system model is infered. And the decoupling linearization of state feedback for the joint system is made, which makes the system become linear system with six degrees of freedom. With the control of pseudo-derivative feedback which proportional plus goes first regulator and simulation experiments, it shows that the system of decoupling linearization joint system has the performance of well static, high-speed response, good dynamic characteristics and strong capacity of resisting disturbance.

Key words: Controlled characteristics, Electromagnetic torque, Inverse system decoupling, Magnetic force, Magnetic levitation, Spherical driving joint