29 Oct
2002
29 Oct
'02
11:08 p.m.
At 11:33 PM 10/29/02 -0800, you wrote:
...I am wondering if anybody knows where I can find a
couple super low
inertia motors like some older tape drives and other very rapid
positioning equipment used
-snip-
Motor Moment of Inertia (Jm) = 0.0007 to 0.0009 oz/inch
sec^2
Torque constant (Kt) = 9 oz/inch per Ampere (for 1 Ohm motor, ie. Rdc = 1
Ohm)
Torque constant (Kt) = 14 oz/inch per Ampere (for 2 Ohm
motor, ie. Rdc = 2
Ohm)
Drive shaft = 3/8 in. (diameter)
"Figure of Merit" (FoM) = Kt/(Square root of Rdc) = 9.9 oz-in of
torque per watt disipation
So you want to build a contrabass? I have never heard one...
but I have always been skeptical about its ability to put out HiFi.
The reason is that people use DC servomotors with *brushes*, and
believe, the behavior of these things at low speeds is very nasty
in terms of nonlinearity: static friction, nonlinear torque(i,theta);
so until someone proves me wrong I think that they are just
huge rumble-makers without any HiFi attributes.
Now, if they used a high-grade brushless servo with special
feedback control algorithmics and sensors... and a more reversible,
static friction-less kind of transmission... I might buy the idea.
carlos.
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Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org