By making relative movement between the flexible spline and rigid spline

either of them has a taper hole or taper surface

this results in the perimeter difference 2(（R-r）of flexible spline and rigid spline continuous variation

then realizes continuous variable transmission of the radial harmonic drive with inner wave generator

the radial harmonic drive with outer wave generator

the face harmonic drive

the hermitical harmonic drive and the multi-stage harmonic drive etc..Based on this measure

the radial harmonic drive device with inner wave generator is contrived.Calculation shows that the continuous variable transmission of harmonic drive can provide high variable transmission ratio

and the higher the maximum transmission ratio is required

the higher precision the flexspline and rigid spline needed.