Motor
To rotate the disc, it must be connected to a driving source, such as a motor. They are commonly driven by pulse-width modulation (PWM) generators (though modeled as if driven by linear-gain amplifiers) and provide position information via attached digital encoders. The Maxon Precision Motors Re-35 DC brushed motor meets all of the design requirements when geared to the disc at a load-to-motor ratio of 1:2, and has a form factor on the order of the disc radius.
Key specs
Quantity | Value | Units |
---|---|---|
nominal speed | 49.5 | rps |
- | 311 | rad/s |
max (continuous) torque | 105 | mNm |
max (stall) torque | 493 | mNm |
max voltage | 48 | V |
armature resistance | 11.50 | Ohm |
armature inductance | 3.16 | mH |
damping coefficient | 1.22 | mNm / (rad/s) |
torque constant | 119.00 | mNm / A |
back-EMF constant | 0.12 | V / (rad/s) |
armature inertia | 65.5 | g / cm^2 |
Key documentation
Notes
We have modeled the motor as powered by a linear gain amplifier, which is uncommon due to power efficiency and cost concerns. Instead, we use a more conventional pulse-width modulation (PWM) generator. We treat the PWM output signal as if it were the equivalent output from a linear gain amplifier, since PWM generators that produce a high-frequency output have approximately the same effect, and mathematical representations of PWM signals are cumbersome.