Hello,

Neat robots!

Problem number 1: Jerky

You have your sprockets the wrong way round. It looks like your driving
gear is 1.5" diameter, which means that each step drives the chain
about 0.3".  The small ones look about 0.5", so if your motor uses them
then each step is smaller (maybe 0.1").  Also, you should research the
techniques of half-stepping, which should allow you to achieve 32
'steps' per revolution.  There is another technique called
microstepping, but it is more difficult to implement.

Problem number 2: Power consumption

Unfortunately, the coils in the stepper motor are just lengths of wire,
with a fairly low resistance, so the current is high.  If you keep the
current turned on you can hold the stepper motor in a fixed position,
however, if your motor will not be subject to external forces (and the
robot is pretty small and light weight) then you could maybe try pulsing
the coils to make the motion, and then leaving them off when you know
the motor has reached the next step position.  I have not tried this, it
is only an idea.

Problem n:

Other small stepper motors can be found in floppy disk drives.
Vibrating pager motors are small (but they are not stepper motors)
Increasing torque can be done with a gearbox or series of rubber bands
and pulleys.
That's it for now.

Oh, did I say, neat robots!

Andy

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