MDC2250 closed loop RPM problems

7 years 6 months ago #29527860 by rezophonic
I was tuning the PID for Closed Loop Count mode on an MDC2250 when the motor began maxing out at around 300 RPMs, then later at just under 90 RPMs. I tried replacing the battery, which did not help. Moreover, it seemed to reach its usual max RPMs in Open Loop mode.
Thanks in advance.

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7 years 6 months ago #29527861 by Griffin Baker
Replied by Griffin Baker on topic Re:MDC2250 closed loop RPM problems
I take it nothing in your hardware wiring has changed?

In the roborun+ utility, does a fault status light come on?

Have you tried swapping the positive and negative leads on the motor output?

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7 years 6 months ago #29527862 by rezophonic
Nothing in the wiring has changed; only software variables have. No fault lights have come on. It still runs fine in Open Loop, just not Closed (I only tried Count Position, which is what I need).

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7 years 6 months ago #29527864 by Griffin Baker
Replied by Griffin Baker on topic Re:MDC2250 closed loop RPM problems
If the motor goes into run away mode (Spins in one direction and doesn\'t stop), then you may need to swap the positive and negative leads from the motor channel.

When the motor is in the closed loop count, the motor is not moving until given a command.

If you go into the console tab, type in the following and verify that the motor spins for x amount of turns as specified by the command.

!P 01 10
Click Send
The motor should spin around 10 times. The command !P is telling the motor to go to position count 10.

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7 years 6 months ago #29527866 by rezophonic
The motor does not go into run away, and it does stop at the positions or relative positions I give it. The problem is that it moves to those positions at a very low RPM and no settings I change seem to affect this. I have double checked my max RPMs for the controller and specific motors, and I have double checked my battery. I have even double checked that I can exceed the RPMs it maxes at in Closed Loop mode when I instead set it to Open Loop, so the hardware is obviously physically capable of reaching higher RPMs than it does when in Closed Loop mode. I have varied my PID values with no effect.

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7 years 6 months ago #29527870 by Griffin Baker
Replied by Griffin Baker on topic Re:MDC2250 closed loop RPM problems
Have you tried running a command to set your motor RPM? In the user manual for the position mode velocity page 171.

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7 years 6 months ago #29527884 by rezophonic
I did try this, but with mixed results. It seemed to try and utilize that speed instead of just establishing it as max RPMs even when PID parameters would have resulted otherwise. Moreover, declaring a positive speed before a negative relative position change command resulted in the wheel spinning the wrong way (positive) indeffinitely and never reaching the relative position change.

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7 years 6 months ago #29527885 by Griffin Baker
Replied by Griffin Baker on topic Re:MDC2250 closed loop RPM problems
I\'m not sure at this point. If you have already set your max rpm values and made adjustments to your pid, I\'m not sure what is causing for this to happen.

I\'ll need you to clarify for me as I\'m having a hard time understanding. When you are in a negative relative position(count = -100) and you set a positive count command to the motor, the motor spins in the reverse direction. Is this correct?

Also if you could, please provide the firmware version you are using with your controller. Console tab type in ?fid and click send.

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6 years 10 months ago #29528605 by OHalloran
I was having the same problem and after resetting the controller to defaults, realised that the "Turns Min to Max" adjustment in Closed Loop Parameters has a huge influence on the motor characteristics. By lowering the turns count, the motor runs faster and vice versa. Maybe someone can explain how this parameter is used in the algorithm.

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6 years 10 months ago #29528608 by roboteq
It is a little difficult to explain. Look first for the description in the manual.

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