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Unread 18-03-2010, 12:08
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Re: CIM Motor Strength

Quote:
Originally Posted by Ether View Post
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.

~
Oooohhh. Good point. That's a reasonable assumption to make in absence of a clamp-on ammeter. In fact, if they're using a straight up winch style lift, it should have a reasonably constant load on it after the first second or so. You could probably just figure the motor speed on the average lift time and go with it. It'd give you a built in bump to the low-speed, high-torque side so it should be pretty safe.
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