Machsupport Forum
Third party software and hardware support forums. => dspMC/IP Motion Controller => Topic started by: tcustom on April 16, 2016, 09:32:51 PM
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Hello,
Hope that somebody can understand my poor english.
I use Mr-J2s servos for my machine. I think my servos are well tuned, but I can't find any reasonable values for PID in DSPMC.
I already read DSPMC integration manual several times, and tried many times to make it stable. But I can't yet.
This is what I did.
1. First of all, I tuned servo drivers through Mitsubishi servo tuning program.
2. Open DSPMC plugin window, then set velocity 10000, acceleration 1000, distance 0.1, P : 100, D and I : 0, lowpass filter : 5.
3. Execute move and increase P gain until axis can move.
4. Add D and I gains gradually. (status graph doesn't change properly.)
5. After I make graphs (red and blue) as close as possible, then I put larger value for distance (ex: 1~3mm) and execute.
6. Motors are vibrate and make loud noise like grinder when they moving.
I already did this a dozen times. So I add Accel,Decel and S-pattern constants in MR-J2S drivers.(parameter 11,12,13)
After I add this, motor looks stable but it can't follow commands quickly.
Isn't there anybody use Mitsubishi servo motors?
Please give me a guideline.
Thank you.
P.S. What is the purpose of 'velocity feed foword'?
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Torque command input work best with analog control. make sure 0 to +-9v produce 0 to max torque (or speed) on the motor.
you can verify this by putting 5 volts on the analog command input and this should produce 1/2 max power (or speed) at the motor.
you can then make all PID param to zero and then start adding P until you have good motion. do not put too much P, as it may produce grinding noise. Set low pass filter to 5. Set I to 10 and Max Error I to 250. You can add D to reduce oscillations.
Velocity feed forward produce more power at high speed and less power at low speed. this helps to reduce following error at high speeds.
hope this helps.
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Hello,
Thanks for your answer.
You mean that I need to set my servo amps to 'torque control mode'?
If then I also change wiring.
Mitsubishi servos use +-8v for torque command.
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yeah 0 to +-8v is ok too. I dont think applying +-10v will do any damage. if you command accel/velocity within the servo drive/motor limits, dspmc will not put out more than +-8volts.
If changing wires too much trouble, you can try velocity mode first.
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I already did it with velocity control mode.
There is nothing I can do anymore with velocity mode?
If I change to torque mode, I need to change wiring of servo drivers connector.
I want to do everything I can do in speed control mode first.
Thank you.