I experience the last months some very troublesome issues with my DDM85 mount that is installed on a remote observing facility in Spain. The mount is an incremental encoder version.
The mount is used for automated variable star surveys and has a 16”F6.7 Corrected-Dall Kirkham mounted on it. It sweeps from object to object, takes snapshots and it’s mixed with some long timeseries where it stays on the same object for several hours. Hence, the telescope is slewing around a lot.
The nature of the problem is that I get a multitude of “position errors”. Most of the times this happens in RA-axis, but sometimes it also happens on DEC-axis.
I wake up and see in the log a lot of position errors, mostly he could correct himself.
Sometimes (a lot) he cannot correct the error and then the mount stalls and I find it crashed. Very dangerous because when it would start to rain the autopark from cloudwatcher will NOT work because mount is crashed.
Other times he just stops tracking for several hours, but doesn’t show a “position error”.
Because I sleep during the night and the telescope doesn't snow much issues when doing snapshots in the beginning of the night, I'm not around when it happens. Usually it happens from 2-5am orso, when the telescope is busy with taking a long timeseries on an object.
Last night it was quite bad. I woke up around 5am and found the mount pointing upwards and has been crashed. Stop-start motors and trying to park the mount resulted in a series of uncorrectable position-errors. I had to stop-start motors again and again to move the mount even a bit. I park the mount horizontally (under a roof), and just before parking even the slightest move on the RA-axis would result in a crash. I retried and retried. I can only close the roof when mount is in park-position. Motor on/off, then autoslew on/off and also power to the mount on/off. Almost 20 times until finally during one of these attempts autoslew itself crashed and windows reported error and killed autoslew. When I restarted autoslew after that crash the mount slewed around happily like nothing happened. 😕 This makes me wonder if the problem is software?
When I do the motor calibration (when you power on the motors for first time), it most of the time shows a sinus wave, but lately these sinus waves are bit irregular and smaller and far away from each other.
I tried aproach after aproach after aproach to correct this:
-Rebalance several times. (Using help from the guys from the remote site.)
-New motor tuning. Fast & high performance mixed.
-Manual motor tuning. Usually the high performance auto tuning gives the best results and nothing weird to see there...
-New mount model, then different pointing models with different settings.
-Do homing position routine every night.
-Place the flexibility of position high (up to 30 degrees). But even then it crashes, when I place it low (1 degree), it shows a train of position errors.
Nothing seems to help.
What is weird is that these kind of errors sometimes are gone away for some nights, then slowly it becomes worse and worse.
[Tuning Parameter of Axis 1]
Velocity Proportional Factor KP=1800
Velocity Integral Factor KI=100000
Position Proportional Factor KP=20
[Fast Tuning Parameter of Axis 1]
Velocity Proportional Factor KP=600
Velocity Integral Factor KI=30000
Position Proportional Factor KP=4
[Filter Parameter of Axis 1]
Filterfrequency of velocity measurement=2000
Filter Gain of Current=1
Filter numerator of Current Tz=0
Filter dunmerator of Current DZ=0
Filter numerator of Current Wz=3553058
Filter denominator of Current Tp=1
Filter denominator of Current Dp=7540
Filter denominator of current Wp=3553058
[Autofind Parameter of Axis 1]
No Hall measuring time (ms)=25
No Hall step size (degree)=12
No Hall test current (A)=1.30000000819564
[Tuning Parameter of Axis 2]
Velocity Proportional Factor KP=2355.138460584
Velocity Integral Factor KI=180000
Position Proportional Factor KP=19.8
[Fast Tuning Parameter of Axis 2]
Velocity Proportional Factor KP=850
Velocity Integral Factor KI=39000
Position Proportional Factor KP=4
[Filter Parameter of Axis 2]
Filterfrequency of velocity measurement=2000
Filter Gain of Current=1
Filter numerator of Current Tz=0
Filter dunmerator of Current DZ=0
Filter numerator of Current Wz=3553058
Filter denominator of Current Tp=1
Filter denominator of Current Dp=7540
Filter denominator of current Wp=3553058
[Autofind Parameter of Axis 2]
No Hall measuring time (ms)=22
No Hall step size (degree)=12
No Hall test current (A)=1.72799998894334
Anybody who can give my ANY insight is greatly appreciated !
Question
sdufoer
All,
I experience the last months some very troublesome issues with my DDM85 mount that is installed on a remote observing facility in Spain. The mount is an incremental encoder version.
The mount is used for automated variable star surveys and has a 16”F6.7 Corrected-Dall Kirkham mounted on it. It sweeps from object to object, takes snapshots and it’s mixed with some long timeseries where it stays on the same object for several hours. Hence, the telescope is slewing around a lot.
The nature of the problem is that I get a multitude of “position errors”. Most of the times this happens in RA-axis, but sometimes it also happens on DEC-axis.
I wake up and see in the log a lot of position errors, mostly he could correct himself.
Sometimes (a lot) he cannot correct the error and then the mount stalls and I find it crashed. Very dangerous because when it would start to rain the autopark from cloudwatcher will NOT work because mount is crashed.
Other times he just stops tracking for several hours, but doesn’t show a “position error”.
Because I sleep during the night and the telescope doesn't snow much issues when doing snapshots in the beginning of the night, I'm not around when it happens. Usually it happens from 2-5am orso, when the telescope is busy with taking a long timeseries on an object.
Last night it was quite bad. I woke up around 5am and found the mount pointing upwards and has been crashed. Stop-start motors and trying to park the mount resulted in a series of uncorrectable position-errors. I had to stop-start motors again and again to move the mount even a bit. I park the mount horizontally (under a roof), and just before parking even the slightest move on the RA-axis would result in a crash. I retried and retried. I can only close the roof when mount is in park-position. Motor on/off, then autoslew on/off and also power to the mount on/off. Almost 20 times until finally during one of these attempts autoslew itself crashed and windows reported error and killed autoslew. When I restarted autoslew after that crash the mount slewed around happily like nothing happened. 😕 This makes me wonder if the problem is software?
When I do the motor calibration (when you power on the motors for first time), it most of the time shows a sinus wave, but lately these sinus waves are bit irregular and smaller and far away from each other.
I tried aproach after aproach after aproach to correct this:
-Rebalance several times. (Using help from the guys from the remote site.)
-New motor tuning. Fast & high performance mixed.
-Manual motor tuning. Usually the high performance auto tuning gives the best results and nothing weird to see there...
-New mount model, then different pointing models with different settings.
-Do homing position routine every night.
-Place the flexibility of position high (up to 30 degrees). But even then it crashes, when I place it low (1 degree), it shows a train of position errors.
Nothing seems to help.
What is weird is that these kind of errors sometimes are gone away for some nights, then slowly it becomes worse and worse.
Some motor-ci error logs:
04:58:10.164: Axis 2 Pos:-109.90° Curr:+00.4A MagAng:+335° PosErr:+04.86arcsec 04:58:12.347: Axis 1 slewing to -38.21 04:58:12.371: Axis 2 slewing to -109.89 04:58:12.981: Axis 1 slewing to -38.20 04:58:13.006: Axis 2 slewing to -109.89 04:58:13.220: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+14946.64arcsec 04:58:16.326: Axis 2 Pos:-109.90° Curr:+00.2A MagAng:+335° PosErr:-00.02arcsec 04:58:19.382: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+15921.74arcsec 04:58:22.489: Axis 2 Pos:-109.90° Curr:+00.4A MagAng:+335° PosErr:+00.00arcsec 04:58:25.525: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+16899.64arcsec 04:58:28.667: Axis 2 Pos:-109.90° Curr:+00.4A MagAng:+335° PosErr:+00.00arcsec 04:58:31.608: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+17867.23arcsec 04:58:32.636: Axis 1 trying to autocorrect tracking error 04:58:34.963: Axis 2 Pos:-109.90° Curr:+00.2A MagAng:+335° PosErr:-00.02arcsec 04:58:38.100: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+645.13arcsecAnd bit later during crash itself.
05:00:22.588: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+6527.77arcsec 05:00:25.555: Axis 2 Pos:-109.90° Curr:+00.2A MagAng:+335° PosErr:+00.00arcsec 05:00:28.685: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+7498.19arcsec 05:00:31.646: Axis 2 Pos:-109.90° Curr:+00.2A MagAng:+335° PosErr:+00.00arcsec 05:00:34.773: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+8467.02arcsec 05:00:37.395: Axis 1 slewing to -37.59 05:00:37.420: Axis 2 slewing to -109.89 05:00:37.760: Axis 2 Pos:-109.90° Curr:+00.3A MagAng:+335° PosErr:+08.06arcsec 05:00:39.957: Axis 1 slewing to -37.59 05:00:39.983: Axis 2 slewing to -109.89 05:00:40.591: Axis 1 slewing to -37.59 05:00:40.616: Axis 2 slewing to -109.89 05:00:40.921: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+17175.15arcsec 05:00:43.943: Axis 2 Pos:-109.90° Curr:+00.5A MagAng:+335° PosErr:-00.14arcsec 05:00:47.158: Axis 1 trying to autocorrect tracking error 05:00:48.457: Axis 1 Pos:-042.35° Curr:+00.1A MagAng:+204° PosErr:+00.40arcsec 05:00:49.516: Axis 2 Pos:-109.90° Curr:+00.1A MagAng:+335° PosErr:+00.08arcsec 05:00:54.690: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+968.47arcsec 05:00:55.629: Axis 2 Pos:-109.90° Curr:+00.1A MagAng:+335° PosErr:-00.04arcsec 05:01:00.787: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+1938.87arcsec 05:01:01.726: Axis 2 Pos:-109.90° Curr:+00.1A MagAng:+335° PosErr:+00.02arcsec 05:01:06.870: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+2906.74arcsecAnd still bit later:
05:01:44.495: Axis 2 Pos:-109.90° Curr:+00.1A MagAng:+335° PosErr:+00.00arcsec 05:01:49.758: Axis 1 Pos:-042.35° Curr:+05.0A MagAng:+204° PosErr:+9731.88arcsec 05:01:50.613: Axis 2 Pos:-109.90° Curr:+00.1A MagAng:+335° PosErr:+00.02arcsec 05:01:51.406: Axis 1 slewing to -37.28 05:01:51.431: Axis 2 slewing to -109.89 05:01:53.963: Axis 1 trying to autocorrect tracking error 05:01:55.277: Axis 1 Pos:-042.36° Curr:+00.1A MagAng:+204° PosErr:+00.26arcsec 05:01:55.326: Axis 1 slewing to -37.28 05:01:55.351: Axis 2 slewing to -109.89 05:01:57.494: Axis 2 Pos:-109.89° Curr:+01.6A MagAng:+335° PosErr:+00.36arcsec 05:01:57.580: Axis 1 slewing to -37.27 05:01:57.604: Axis 2 slewing to -109.89 05:01:59.093: Axis 12 Tracking errors within 60 seconds, giving up 05:02:01.200: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:02:03.308: Axis 2 Pos:-109.89° Curr:+01.2A MagAng:+335° PosErr:+00.00arcsec 05:02:07.393: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:02:09.474: Axis 2 Pos:-109.89° Curr:+01.2A MagAng:+335° PosErr:+00.02arcsec 05:02:13.564: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:02:15.633: Axis 2 Pos:-109.89° Curr:+01.3A MagAng:+335° PosErr:+00.00arcsec 05:02:19.728: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:02:21.785: Axis 2 Pos:-109.89° Curr:+01.3A MagAng:+335° PosErr:+00.00arcsecAnd then when it finally crashes:
05:02:58.780: Axis 2 Pos:-109.89° Curr:+01.3A MagAng:+335° PosErr:-00.02arcsec 05:03:02.885: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:03:04.957: Axis 2 Pos:-109.89° Curr:+01.3A MagAng:+335° PosErr:+00.06arcsec 05:03:08.519: Axis 1 Error Cleared 05:03:08.527: Axis 1 turned on Motor 05:03:08.532: Axis 1 turned off Motor 05:03:08.568: Axis 1 turned on Motor 05:03:09.057: Axis 1 Pos:-042.36° Curr:+01.9A MagAng:+204° PosErr:+01.81arcsec 05:03:09.751: Axis 1 slewing to 0.05 05:03:09.776: Axis 2 slewing to 0.22 05:03:11.224: Axis 2 Pos:-108.55° Curr:+01.6A MagAng:+352° PosErr:-00.60arcsec 05:03:13.527: Axis 1 trying to autocorrect error and slewing again to 0.05 05:03:18.252: Axis 1 autocorrect slewing error failed 05:03:18.281: Axis 1 Pos:-042.35° Curr:+00.0A MagAng:+204° PosErr:+00.02arcsec 05:03:18.311: Axis 2 Pos:-101.14° Curr:+01.5A MagAng:+351° PosErr:+30.07arcsec 05:03:18.445: Axis 12 Tracking errors within 60 seconds, giving up 05:03:24.439: Axis 2 Pos:-067.17° Curr:+00.7A MagAng:+085° PosErr:+00.00arcsec 05:03:24.628: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:03:30.557: Axis 2 Pos:-067.17° Curr:+00.8A MagAng:+085° PosErr:+00.00arcsec 05:03:30.745: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:-00.02arcsec 05:03:36.708: Axis 2 Pos:-067.17° Curr:+00.8A MagAng:+085° PosErr:+00.00arcsec 05:03:36.898: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:-00.04arcsec 05:03:42.836: Axis 2 Pos:-067.17° Curr:+00.7A MagAng:+085° PosErr:-00.02arcsec 05:03:43.026: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:03:48.999: Axis 2 Pos:-067.17° Curr:+00.7A MagAng:+085° PosErr:+00.00arcsec 05:03:49.178: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsec 05:03:55.141: Axis 2 Pos:-067.17° Curr:+00.7A MagAng:+085° PosErr:-00.02arcsec 05:03:55.331: Axis 1 Pos:-042.36° Curr:+00.0A MagAng:+204° PosErr:+00.00arcsecThese are the motor settings nowadays:
[Tuning Parameter of Axis 1] Velocity Proportional Factor KP=1800 Velocity Integral Factor KI=100000 Position Proportional Factor KP=20 [Fast Tuning Parameter of Axis 1] Velocity Proportional Factor KP=600 Velocity Integral Factor KI=30000 Position Proportional Factor KP=4 [Filter Parameter of Axis 1] Filterfrequency of velocity measurement=2000 Filter Gain of Current=1 Filter numerator of Current Tz=0 Filter dunmerator of Current DZ=0 Filter numerator of Current Wz=3553058 Filter denominator of Current Tp=1 Filter denominator of Current Dp=7540 Filter denominator of current Wp=3553058 [Autofind Parameter of Axis 1] No Hall measuring time (ms)=25 No Hall step size (degree)=12 No Hall test current (A)=1.30000000819564 [Tuning Parameter of Axis 2] Velocity Proportional Factor KP=2355.138460584 Velocity Integral Factor KI=180000 Position Proportional Factor KP=19.8 [Fast Tuning Parameter of Axis 2] Velocity Proportional Factor KP=850 Velocity Integral Factor KI=39000 Position Proportional Factor KP=4 [Filter Parameter of Axis 2] Filterfrequency of velocity measurement=2000 Filter Gain of Current=1 Filter numerator of Current Tz=0 Filter dunmerator of Current DZ=0 Filter numerator of Current Wz=3553058 Filter denominator of Current Tp=1 Filter denominator of Current Dp=7540 Filter denominator of current Wp=3553058 [Autofind Parameter of Axis 2] No Hall measuring time (ms)=22 No Hall step size (degree)=12 No Hall test current (A)=1.72799998894334Anybody who can give my ANY insight is greatly appreciated !
What ARE these position errors exactly ?
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