Motor to drive flow meter

Questions about using encoders with the Roboclaw product line
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Basicmicro Support
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Re: Motor to drive flow meter

Post by Basicmicro Support » Tue Mar 27, 2018 9:38 am

18rpm is really good for that motor. So yes, if you need better torque at that speed gearing or a belt reduction is the only real option.

Sounds like a very interesting project. Yes, we'd like to know how it works out.

gusep
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Joined: Sun Mar 18, 2018 4:41 am

Re: Motor to drive flow meter

Post by gusep » Fri Jun 22, 2018 5:38 am

Finally assembled complete pump, motor and electronics.
Would not work correctly. After pulling my hair out I read many posts in this forum.
On the bench I was using a fixed pot as my demand speed.So every time I powered up, the pot was always very close to 1.0V. All working as expected.
But in the final working system the integrator would always start at 2.0V.
The AUTOCALIBRATE would set 2.0V as the mid point. Nothing in the help.
So finally ticked the MCU box and all OK.
So the help needs to clarify this point and the RoboClaw program needs to highlight the AUTOcalibrate ON or OFF
Next week will test with running motor

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Re: Motor to drive flow meter

Post by Basicmicro Support » Fri Jun 22, 2018 10:00 am

When autocalibrate is enabled the Roboclaw reads the voltage of the analog input when it powers up. If the power up takes longer than expected(eg a power supply that has a slow voltage ramp on power up) the auto calibration reading could be invalid.

Im not sure how we can highlight the autocalibrate on/off other than changing the name. It was called MCU mode because a competitor called the function MCU mode and originally we were marketing as an alternative. That is less of the case now of course. It also does more than disable the auto-calibration. It disabled the RC mode shutdown on signal loss.

The MCU mode option is described on page 14 in the "RC and Analog Mode Options" table. The Roboclaw is a very complex device so the manual may not highlight all functions but we do try to do our best. We have forums, support emails and an 800 number for support calls to cover anything the manual may miss.

gusep
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Joined: Sun Mar 18, 2018 4:41 am

Re: Motor to drive flow meter

Post by gusep » Fri Jun 29, 2018 4:06 am

Today tested running assembly.
If I keep the acceleration very low, then the RPM stabilizes to a given flow. Problem that any changes in flow is very slow.
Fast acceleration and the RPM fluctuates over and under like classic too much gain.
So on analysis I need some proportionality in the photo transistor optics. I will make a tapered piston in glass tube.

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Re: Motor to drive flow meter

Post by Basicmicro Support » Fri Jun 29, 2018 9:00 am

Can you compensate for the oscillation by adding differential? I do know slow processes can be a real pain to tune.

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