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Unread 18-03-2010, 10:57
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Ether Ether is offline
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Re: CIM Motor Strength

Quote:
Originally Posted by Kevin Sevcik View Post
OR, they could see about making their robot better. That's no crime.

To answer your question, it depends on the gearing and efficiency of your current system. Gearing is easy to determine, efficiency much less so. Luckily there's a simple way for you to answer your question experimentally.

Grab a clamp on Ammeter and measure the max current draw on your CIM while you're lifting. Whatever current you're currently drawing, a second robot of equal weight will likely double it. So if you're currently pulling 30 amps, a second robot would make 60 amps or so. So then it's a question of if you can actually give the CIM that much current. The Jaguar will happily pump 40 amps to your CIM for quite a while. 50 amps for much less so. 60 amps for not very long at all.

So, one measurement and a little math should give you an answer.
Great suggestion.

If they don't have access to a clamp-on ammeter, they can measure how fast the bot is lifting when the motor sounds like it is under the most load, then calculate how fast the motor is turning. Then use the CIM torque vs speed curve to estimate the torque, then use the CIM torque vs current curve to estimate the current. This assumes, of course, they are applying 100% command to the motor, and that there is 12 volts at the motor. The actual voltage at the motor will be somewhat less than 12V of course, because of voltage drops across battery resistance and external resistance - which is why this is only an estimate.


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