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Unread 19-12-2013, 23:11
James Kuszmaul James Kuszmaul is offline
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FRC #0971 (Spartan Robotics)
 
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Re: combined free speed of 3 motors

Quote:
Originally Posted by Ether View Post
[i]
Go through the attachment to post#1 step-by-step and tell me at what step you disagree or are unconvinced, and I will explain the justification and make explicit any tacit assumptions.
Perhaps I was unclear. I agree with your derivation of the free speed. I agree with the idea that there is a free speed as you describe and that it is of value.
What I am wondering about is your statement that
Quote:
The resulting 'combined' Free Speed (together with the simple-to-calculate Stall Current and Stall Torque) allow you to view the combination as equivalent to a single motor with those characteristics. Treating the combination as equivalent to a single motor allows you to use all the single-motor math you are already familiar with.
(emhasis mine)
I agree that you can calculate numbers for free speed, stall current, and stall torque for the combined motors. It makes intuitive sense why you could use the single motor equations, given that you can find a Kv, Kt, and R, how do you prove (I don't necessarily disagree; I just don't agree) that
T = I * Kt
and
V = I * R + omega / Kv
[Edit: To be clear, how do you prove that these statements apply for the combined motors; I already know that they apply to a single motor]

I presume that I have been unclear in my questions, because I have been asking essentially the same question, phrased differently, the last couple posts.
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