and I'm trying to find out the moment of inertial of the rotor (J), damping ratio of the mechanical system (b),
electromotive force constant (K=Ke=Kt), electric resistance (R), and electric inductance (L) of this dc motor.
All I know is that this dc motor has max of 1.98A, 9-18V range with maximum RPM of 18000. The max rpm of this when 12V is applied
is around 15047 rpm. The speed of this dc motor has 24000 rpm (which is 400 rev/s) when there is no load.
from this information, how do I find obtain values of J, b, K, R, and L for this 9-12V dc motor?
I looked online for something similar but it didn't help me. I'm trying to obtain these values. Are all DC motors
have different values?
Well the Kv is rpm-per-volt (no load) so you can figure this out - this will then give you the torque-per-amp directly as they are related (hint, convert to SI units and radians/second and the constants are the same)
You have to measure the winding resistance. The max current is the current rating to avoid overheating, not related to your parameters. The MoI you'll have to measure again, although you can estimate this from the mass and dimensions of the armature. Damping I've no idea, there's a lot of friction of various kinds. Inductance of a motor is not well defined since the magnetic circuit is not constant, saturation is likely to be happening, and back-EMF will complicate things - again you can try measuring this with an inductance bridge, you won't be able to deduce it.
Yes every DC motor that's different in dimensions will be different, and many will be the same design but differently wound and so electrically different.