gokhan
Junior Member
Posts: 89
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Post by gokhan on Nov 18, 2016 15:40:18 GMT
I think it is very important to shield the motor cables, they spread over a long length. I have just received mine. Some mVolts can make a difference and movement on engines, no? You can compare with my oscilloscope video of noise. www.youtube.com/watch?v=yaUJlDW7I5kfor me 0.5v noise.... !! My friend said that (high voltage) power cable shielding is mostly against capacitive loses rather than interference. He claims that if the distance between power cables and signal cables are more than 50 cm - 1 m. than the shielding effect on interference is neglegable. But I am not an expert and if you recommend I willre consider it. By the way, are you moving the sensors by hand in this video? or motors running?
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Nov 18, 2016 15:55:49 GMT
A friend convinced me that the shielded power cables are overkill. So i will postpone that??? I tested sensor signal with oscilloscope and very little noice so I am very happy on that. Welded parts reduced backlash allot. Increased ramp up and down times from 50 ms to 500 ms and re do the automated motor tuning. Now it is almost usable except one reductor with huge backlash. The new reductors will be delivered next week. But at least i can work(on PID tuning) with this for the moment. I will put a new video after the reductor replacement. Using bolted aluminum profiles is the bolts doesnt hold against intense vibration of the motion simulator. It tends to slide over the bolted part. I did not use any thread locking glue but you can try it. You are right. Alu profiles are very good for quick development but in the long run they are not reliable. Vibration will loosen up the connections due to the fact that soft alu will deform by the load. Threadlock doesn't help the deformation unfortunately. I used Alu for prototyping and I will replace it with a steel platform. But I am long way from that yet. First I need to replace the reductors then I need to decide on controls. I already ordered, GOFLIGHT - GF-TPM - THROTTLE-PITCH MIXTURE , VIRTUALFLY - RUDDO PEDALS , FI - HW-FFB-CSN FORCE FEEDBACK CESSNA YOKE . I will also get Brunner products. Any opinion, comments on these products are welcome. Once I decide the best combination, I will finalise the shape and the dimensions of the steel platform.
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Post by riton39 on Nov 18, 2016 20:17:38 GMT
I think it is very important to shield the motor cables, they spread over a long length. I have just received mine. Some mVolts can make a difference and movement on engines, no? You can compare with my oscilloscope video of noise. www.youtube.com/watch?v=yaUJlDW7I5kfor me 0.5v noise.... !! My friend said that (high voltage) power cable shielding is mostly against capacitive loses rather than interference. He claims that if the distance between power cables and signal cables are more than 50 cm - 1 m. than the shielding effect on interference is neglegable. But I am not an expert and if you recommend I willre consider it. By the way, are you moving the sensors by hand in this video? or motors running? The manufacturer's documentation indicates that the motor cables must be shielded. In this video I turn the potentiometer with the hand. Unshielded motor cable, shielded potentiometer cable. AMD close to drives, without shielding case for AMC
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Post by clyevo on Nov 19, 2016 2:26:29 GMT
My friend said that (high voltage) power cable shielding is mostly against capacitive loses rather than interference. He claims that if the distance between power cables and signal cables are more than 50 cm - 1 m. than the shielding effect on interference is neglegable. But I am not an expert and if you recommend I willre consider it. By the way, are you moving the sensors by hand in this video? or motors running? The manufacturer's documentation indicates that the motor cables must be shielded. In this video I turn the potentiometer with the hand. Unshielded motor cable, shielded potentiometer cable. AMD close to drives, without shielding case for AMC I agree with you on shielding the motor cable, because it uses high frequency carrier signal with very high voltage it produce buttload of electrical and magnetic field. Shielded cable would not eliminate it completely but helps a lot. Any significant improvement after using shielded motor cable? Since you have oscilloscope maybe you show us picture after and before using shielded motor cable?
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Nov 19, 2016 6:04:29 GMT
The manufacturer's documentation indicates that the motor cables must be shielded. In this video I turn the potentiometer with the hand. Unshielded motor cable, shielded potentiometer cable. AMD close to drives, without shielding case for AMC I agree with you on shielding the motor cable, because it uses high frequency carrier signal with very high voltage it produce buttload of electrical and magnetic field. Shielded cable would not eliminate it completely but helps a lot. Any significant improvement after using shielded motor cable? Since you have oscilloscope maybe you show us picture after and before using shielded motor cable? Good idea, i will try to record it and share it.
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Post by riton39 on Nov 19, 2016 18:09:17 GMT
For the moment, I have not received all my parts to remake the wiring, the shields .... When all will be ok, I will make a video to compare the difference.
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Nov 27, 2016 14:20:28 GMT
I agree with you on shielding the motor cable, because it uses high frequency carrier signal with very high voltage it produce buttload of electrical and magnetic field. Shielded cable would not eliminate it completely but helps a lot. Any significant improvement after using shielded motor cable? Since you have oscilloscope maybe you show us picture after and before using shielded motor cable? Good idea, i will try to record it and share it. here are some recordings on osc. before shielded power cables. I will definetely replace all cables with good shielded ones and record again.
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Nov 27, 2016 14:31:09 GMT
Finally I received and replaced the reductors. I still have backlash from the keyways and the keys. I will also replace the key with tight fitting ones. But for the reductors part the backlash problem seems to be over.
I also experimented withfew of the vfd parameters.
The first one was "slip compansation time constnt". I didn't öakee a noticable difference.
Second was the "filter time contant for the analogue input pin 53" which was the speed input pin I use. I increased it from 1 ms to 17 msec and it basically stopped the jerking in the platform specially when moving down.
Third was the ramp paraameters. I set the ramp type to "s-type" from "lineer", decreased ramp up time from 500 ms to 300 ms and increased the ramp down time from 500 ms to 600 ms.
result is promissing. here is the video. what do you think?
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Nov 27, 2016 14:35:01 GMT
I am having low frequency oscillation now. I could stop this by increasing "oversampling ADC" from 1 to 2-4, using Fabi' s sw. at 4 it definately stops, but it also slows down the reaction of the platform to small movements. here is the video. What do you think?
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Post by tronicgr on Nov 27, 2016 16:28:16 GMT
Good idea, i will try to record it and share it. here are some recordings on osc. before shielded power cables. I will definetely replace all cables with good shielded ones and record again. Shielded wiring for the analog is needed, not only for the potentiometers but for the analog out signal from the 6dof ext to the vfd inverters to void feedback noise. Thanks for sharing these videos!
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Post by tronicgr on Nov 27, 2016 16:33:41 GMT
I am having low frequency oscillation now. I could stop this by increasing "oversampling ADC" from 1 to 2-4, using Fabi' s sw. at 4 it definately stops, but it also slows down the reaction of the platform to small movements. here is the video. What do you think? This slow oscillation is from the increased ramp settings of the vfd. You can try decreasing these, and add some ramp from the amc1280usb menu (P values has a ramp setting). Thanks Thanos
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Dec 2, 2016 7:48:33 GMT
I am having low frequency oscillation now. I could stop this by increasing "oversampling ADC" from 1 to 2-4, using Fabi' s sw. at 4 it definately stops, but it also slows down the reaction of the platform to small movements. here is the video. What do you think? This slow oscillation is from the increased ramp settings of the vfd. You can try decreasing these, and add some ramp from the amc1280usb menu (P values has a ramp setting). Thanks Thanos Dear Thanos, I couldn' t find the ramp setting in the menu. There is max online speed, if it is what you mean? Can you elaborate a bit more?
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Dec 2, 2016 8:00:14 GMT
here are some recordings on osc. before shielded power cables. I will definetely replace all cables with good shielded ones and record again. Shielded wiring for the analog is needed, not only for the potentiometers but for the analog out signal from the 6dof ext to the vfd inverters to void feedback noise. Thanks for sharing these videos! I replace #3 actuator's power cable with shielded power cable. To make the comparison, I connected the oscilloscope to #3 and #6 and power them up one by one while recording the video. All the sensor cables and AMC to VFD cables are shielded. AMC is in a metal box, shielded. One vfd is sufficient to create such noice, although the magnitude of the spikes seems to be lower in the shielded cable case. I think it is all happening in the VFD box(where VFDs are installed) where all control cables are open for pin connections. Still I am not sure if this noice is causing any problem at all, since VFDs' are not reacting to those high freq. spikes(analogue input filtering constant 17ms filtering them out I guess?). here is the video.
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Post by riton39 on Dec 2, 2016 9:33:56 GMT
You have to watch on + 5v if you also have parasites.At home, there are also parasites on the + 5v.I think it should also filter, or isolate the power + 5v USB.Filter 5V power use a self-powered USB hub?I am trying to redo the connections at the moment with shielded cables,Soon my tests
is your VFD box shielded too ?
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Dec 2, 2016 14:43:41 GMT
This slow oscillation is from the increased ramp settings of the vfd. You can try decreasing these, and add some ramp from the amc1280usb menu (P values has a ramp setting). Thanks Thanos Dear Thanos, I couldn' t find the ramp setting in the menu. There is max online speed, if it is what you mean? Can you elaborate a bit more? Sorry, I found it. It appears once you change speed settings right? I also found out that the main reason for my low freq oscillation was min speed setting. It was set to 2, now 5. It stopped oscillation.
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