Silent Robot

Video

When oiled, the mechanics are fairly silent. What usually makes noise in robots like this are the stepping of the stepper motors.

Using microstepping helps a lot, but I went further. I use dither stepping, where microstepping and digital signal processing are combined directly with cybernetics to give smooth silent movement to the robot.

In the beginning I used microstepper controllers, but they have been replaced with H-bridges driving the stepper motors directly. They are controlled by an Atmel microcontroller which in the background runs my interrupt based driver routine. It uses negative positional feedback with smooth bessel filters implemented as coupled differential equations.
It is fast too, and do not use much of the processing power.

(The mechanics make some small noise when moved very fast.)

Any comment?
kim.oyhus@gmail.com