SDC1130 sudden stop at reaching desired position

5 years 2 months ago #29531117 by davidk
If you need more data about my issue, I can send you logs. I need this working just like SDC2130. Stopping suddenly at reaching desired position compromises the loop since it won't handle the dolly's inertia.

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5 years 2 months ago #29531119 by TechSupport
This doesn't appear as something we can get fixed anytime soon. Perhaps maybe do a swap to the SDC2130?

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5 years 2 months ago #29531126 by ied168
I have a similar problem running in closed-loop count position, but I am running the SDC2130. Attached are the charts for two scenarios: 1) moving from position 400000 to -500 and the motor will make a very ABRUPT stop. 2) moving from position 300000 to -500 and the motor will make a soft stop. Speed set with !S 1 10000. Yes, if I lower the speed (!S 1 5000), all stops are gentle, but 5000 is too slow for me. At a displacement of about 400k, I can hear the motor whirl at a high speed, but I don't hear the motor go as fast if only displacing 300k. Based on the charts, the tracking has a VERY STEEP curve for 400k vs the 300k, so this should be a command problem with the controller? Would adjusting PID or any settings help?
Attachments:

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5 years 2 months ago #29531128 by TechSupport
PID is only one area of focus, You still have speed and acceleration parameters to adjust.

It also sounds like you have the loop error detection enabled, set it to disabled.

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5 years 2 months ago #29531132 by ied168
Loop error detection didn't have any effect. I ended up lowering the speed !S 1 9000 instead of !S 1 10000. This is more of a workaround than a fix because the cause of problem is still not known. If the motor is going too fast (i.e. hits some speed), the controller seems to forget to ramp down faster, and then of course the position should overshoot, BUT the controller DOES NOT LIKE POSITION OVERSHOOT, so it just makes a very ABRUPT stop.

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5 years 2 months ago #29531133 by TechSupport
which firmware date code are you on?

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5 years 2 months ago #29531134 by ied168
Firmware 1.4b 3/31/2015. Retested at !S 1 10000 and ~600k displacement - see attached log file and screen shot. You can see the Speed (dark green line) has a very steep angle (just like the Track).
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5 years 2 months ago - 5 years 2 months ago #29531135 by TechSupport
Let's clear some things up. The mode the the OP in this thread was using is position count. Therefore his command is !P. From what I gather is you are using speed mode since you are using !S which is a speed command.

If this is not the case, then please specify which mode you are using.

If you are using position relative then it is !G.

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5 years 2 months ago #29531136 by ied168
I am using Closed Loop Count Position mode. I am using !P to move to certain positions (e.g. !P 1 600000), and I am using !S to control the velocity. (reference Roboteq user manual v1.3, p.104)

Attached is additional chart data and screenshot of the same displacement of ~600k counts, but !S 1 9000 instead of !S 1 10000. So just a slight drop in speed and I get a dramatically different curve (soft stop at desired position).
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5 years 2 months ago #29531137 by TechSupport
It sounds like the adjustments to make the speed changes is what causes the problem. If you leave the speed alone, does the problem exist?

Changing the speed on the fly has an impact on the closed loop so in this case, there is likely another parameter that the change of speed does not like causing this problem to occur. It is probably the acceleration parameter not liking the changes.

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