Wave Generator

波发生器Advanced

The input component of a harmonic reducer: an elliptical cam and flexible bearing that force the flexspline into an oval.

The wave generator is one of the three core parts of a harmonic reducer, alongside the flexspline and the circular spline, and it's the input, connected directly to the motor. It's made of an elliptical cam wrapped in a thin-wall flexible bearing; inserted inside the thin-walled flexspline, it forces the flexspline into an oval shape so the flexspline's teeth mesh with the circular spline's internal teeth only at the two ends of the long axis. As the wave generator makes one full turn, the meshing points travel all the way around too, and since the flexspline typically has 2 fewer teeth than the circular spline, the flexspline ends up shifted by only 2 teeth relative to the circular spline per input revolution — producing a very large reduction ratio, commonly tens to over a hundred to one in a single stage. This is how harmonic reducers achieve a compact size with very little backlash, which is why they're used so widely in robot-arm and humanoid-robot joints.

ExampleA harmonic reducer with a 100:1 ratio: a 200-tooth flexspline and a 202-tooth circular spline — the wave generator turns 100 times for every 1 output turn of the flexspline.

Also called: Wave Generator Cam, Elliptical Cam
Related: Strain Wave Gear (Harmonic Drive) · Flexspline · Circular Spline · Gear Ratio · Backlash · Thin-Section Bearing
Sources: Strain wave gearing - Wikipedia