Abstract:

In order to solve the problems of complex electromagnetic drive structure, difficult coupling magnetic field modelling and magnetic moment singularity in the current spherical joints, a permanent magnet flexible spherical wrist joint based on the rotational co-axis effect is designed. As for the driving principle, the spatial universal rotating magnetic field generated by the three-axis orthogonal combination coil is used as the driving source, in which, the decoupled coaxial magnetic moment generated by the permanent magnet rotor in synchronous rotation with the field is employed to drive the wrist to achieve two degrees of freedom motion of pitch and yaw. As for improving the systematic ability to resist external disturbance and chattering suppression, this paper adopts a non-singular fast terminal sliding mode control method based on fuzzy algorithm optimization to implement control. The Lyapunov function is used to prove the stability of the system. Simulation and experiments show that the system has good robustness and chattering suppression effect, as a result, output trajectory errors are reduced, high-precision and fast tracking of the expected trajectory of spherical joints are achieved and the adaptability to complex environments is improved.

Key words: permanent magnet flexible spherical joint, rotating magnetic coaxial effect, spatial universal rotating magnetic field, sliding mode control, trajectory tracking