Intelitek SCORBOT-ER 9, Руководство пользователя

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Harmonic Drive Gears
The Harmonic Drive transmission used in the
SCORBOT-ER IX
, shown in Figure
6-6, offers a very high gear ratio.
The Harmonic Drive gears used in the
SCORBOT-ER IX
have four main
components:
• Circular spline:
a solid steel ring, with internal gear teeth, usually fixed to the robot link.
• Wave generator:
a slightly elliptical rigid disk, which is connected to the input shaft, with a ball
bearing mounted on the outer side of the disk.
• Flexspline:
a flexible, thin-walled cylinder, with external gear teeth, usually connected to
the output shaft.
• Dynamic spline: a solid steel cylinder, with internal gear teeth.
The external gear teeth on the flexspline are almost the same size as the internal
gear teeth on the circular spline except there are two more teeth on the circular
spline, and the teeth only mesh when the wave generator pushes the flexspline
outwards.
Because the wave generator is elliptical, the flexspline is pushed out in two
places. As the motor rotates the input shaft, the wave generator rotates and the
location of meshing teeth rotates with it. However, because there are two less
teeth on the flexspline, it has to rotate backwards slightly as the wave generator
rotates forwards. For each complete rotation of the input shaft, the flexspline
moves
backwards by
two teeth.
Figures 6-7 and
6-8 show the
different steps
in this process.
Figure 6-6: Harmonic Drive Structure
User’s Manual 6 - 5 SCORBOT-ER IX
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