This paper proposes a novel rotary vernier actuator which can rotate bidirectionally according to the principle of a linear vernier motor. It is clarified by using 3-D FEM that the cause of the cogging torque and torque ripple is the permeance between the stator and mover and the end effect due to the arc-shaped stator. It is also discussed how the skewed mover or the arrangement of two blocks of the stator can reduce these ripples.
