Simulink DC motor model units confusion
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In the DC motor simulink model in the following link, there are two versions one for simulink and the other for Simscape
My problem is with the units of motor viscous friction constant and angular velocity.
It is N.m.s in simulink version and N.m/rad/sec in the simscape version. However it uses the same equation
If d theta/dt in (rad/sec) so, b should be in (N.m.rad/sec), am i right or what ??
By the way dividing Torque/moment of inertia will give us acceleration in (1/sec^2) how it will be rad/sec after integration ?
A Jenkins on 9 Jan 2015
Radians are a dimensionless quantity, since they are calculated as arc length/radius (whatever units those are measured in would cancel). Therefore having radians as a unit can be cancelled out of an equation. Leaving them in does not change the math, but simply clarifies that the angles should be measured in radians and not degrees.
rad/sec = (arc length / radius) / sec = (meters / meters) / sec = 1/sec