Author Topic: beer robot motor selection  (Read 1043 times)

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Offline brobotTopic starter

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beer robot motor selection
« on: July 14, 2013, 07:34:46 AM »
I'm working on the first phase of a project and I need to build a launch system that can shoot a beer can at precise speeds. The velocities vary from 1-9 m/s, so I was thinking that the best approach would be a pitching machine like design would be best.

Is torque as important as speed for this? It seems like the inertia of the flywheels is what actually will launch the can instead of the motors torque. The biggest problem is that I need to vary the speed from 500-6000 rpms pretty precisely. What sort of motor would work best in that range? It's a slower than most motors go, so would I need to use a gear system to make it work?

Thanks for any help

Offline MrWizard

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Re: beer robot motor selection
« Reply #1 on: July 14, 2013, 09:06:47 AM »
Full or empty beer can ? :-)

Offline jwatte

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Re: beer robot motor selection
« Reply #2 on: July 14, 2013, 02:10:10 PM »
The torque of the motors is somewhat important, as it will reduce the slow-down of the flywheels when they grab the can. If the flywheels are heavy enough, then the motor torque doesn't matter much, other than determine how quickly you can adjust the speed.

Any motor that can get to 6000 rpm will work fine, as almost all motors work well at rpms below their maximum. You can control the speed using PWM if you have the appropriate controller circuit and H-bridge driver for the motor(s). Or, if the motors ever only rotate one way, all you need is a power MOSFET that you can drive with PWM.

Finally, you need an encoder to figure out how fast the motor is spinning, so you can adjust the PWM duty cycle to affect the speed. Some motors have built-in encoders; other systems put the encoders on the output (such as on the flywheels.)


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