Torque and displacement for a micro electromagnetic harmonic drive system

In this paper, a micro electromagnetic harmonic drive system is proposed. For the drive system, the equation of the displacements for the flexible ring under a magnetic field is deduced. Here, both electromagnetic and Van der Waals forces are considered. The equation of the relationship between flexible ring displacements and coil current is given, and based on this, an equation of the output torque for the drive system is provided. Using these equations, the molecule forces between the flexible ring and stator are investigated, and the relationship between flexible ring displacements and coil current and its changes along with system parameters are analyzed. The output torque of the drive system and its changes along with system parameters are also studied. Findings show that the effects of the initial clearance and the coil current on the Van der Waals force between flexible ring and stator are coupled to each other. For a small initial clearance, the effect of the coil current on the van der Waals force becomes large. When the initial clearance is quite small, the effects of the molecule force on the output torque should be considered.