The motion control algorithm based on quaternion rotation for a permanent magnet spherical stepper motor

This paper presented the motion control algorithm based on quaternion rotation for a permanent magnet spherical stepper motor (PMSSM) designed by Gregory S. Chirikjian and David Stein et al. The movement of the rotor was achieved by controlling the current states of the stator coils with relays. While one arbitrary point on the surface of the rotor was expected to move to another appointed one, combining one-step motion into a piecewise continuous trajectory was necessary. The paper provided a control algorithm about kinetic trajectory divided into sections. Thus each segment corresponded one arc and circled around one fixed axis individually, and the continuous movement of the rotor was feasible. The simulation of the motion control algorithm and the error analysis were then presented in the following.