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Post by paulg100 on Nov 9, 2016 9:48:17 GMT
Hi Clyevo
No i dont have that issue, mine is like elctrical interference.
My PI is pretty good, with fast and positive set point (without any d at the moment)
Your video looks like maybe PID issue, can you post a screenshot of your AMC settings from fabis tool in your build thread and we can compare to start
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Post by clyevo on Nov 10, 2016 1:11:37 GMT
Hi Clyevo No i dont have that issue, mine is like elctrical interference. My PI is pretty good, with fast and positive set point (without any d at the moment) Your video looks like maybe PID issue, can you post a screenshot of your AMC settings from fabis tool in your build thread and we can compare to start i've scrapped this 1 year old build few months ago and started a new one with new inverters but i will be very meticulous this time with the EMI suppression. Actually i managed to reduced the oscillation at very lenient PID settings but i cant remember the numbers. My thoughts was the inverter was lagging too much that i am unable to get responsive enough PID settings. If i fail again i will try AC servo motor in the future. I was thinking yesterday it might be EMI causing oscillation. But u have a point as it only oscillate at the end of the movement so it might be more of a PID problem. But then, i never use any shielded cable or shielded chasis or anything except for the potentiometer cable which i suspect is not the best of quality (cheap). Do you see anything in the video that might indicate EMI problem? Like my initial thought could it be the potentiometer is so noisy that it didnt send the correct position to the AMC board causing that to oscillate? I havent bought an oscilloscope and i already scrapped the build because i need the space. So i cant test it. I need some theory why it oscillate so i can prevent the same problem my next build. |
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Post by paulg100 on Nov 10, 2016 6:56:46 GMT
it looks more like PID or VFD settings to me but I'm no expert, I think if it was EMI it would be more erratic and jittery as opposed to sloppy over and under shooting to find setpoint.
If I can get a video made this weekend you will see how emi manifests it self, at least in my sim.
I think one telltale sign with mine is my issue gets worse the more VFD's I power on.
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Post by clyevo on Nov 11, 2016 6:14:46 GMT
it looks more like PID or VFD settings to me but I'm no expert, I think if it was EMI it would be more erratic and jittery as opposed to sloppy over and under shooting to find setpoint. If I can get a video made this weekend you will see how emi manifests it self, at least in my sim. I think one telltale sign with mine is my issue gets worse the more VFD's I power on. I found a good reading on EMC download.sew-eurodrive.com/download/pdf/11535814.pdfThis mainly addressing EMI issues. The first few chapter really help me understand EMI. I hope you can isolate the type of transmission mode of interference that is affecting your system Also hope you get to try tailoring that capacitor based on your oscilloscope reading Looking forward to that Nice you are looking into this problem seriously. Good luck |
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Post by paulg100 on Jan 14, 2017 14:20:02 GMT
tronicgrHI Thanos Just working through my wiring at the moment to try and find where my interference is coming from. Am I correct in saying there will always be continuity between DC ground of AMC1280 and AC system ground, ie if I check between +5v ground of AMC and gearbox shaft there is continuity and Ohms when there should not be? Just wanted to check its not a possible problem with the AMC board? How is it possible to keep AC ground and DC signal ground separate when there is continuity just from the PC/USB cable. Thanks.
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Post by tronicgr on Jan 14, 2017 16:43:34 GMT
tronicgrHI Thanos Just working through my wiring at the moment to try and find where my interference is coming from. Am I correct in saying there will always be continuity between DC ground of AMC1280 and AC system ground, ie if I check between +5v ground of AMC and gearbox shaft there is continuity and Ohms when there should not be? Just wanted to check its not a possible problem with the AMC board? How is it possible to keep AC ground and DC signal ground separate when there is continuity just from the PC/USB cable. Thanks. You need to have common ground for all devices, computer, amc1280usb, vfd inverters, motor casing etc. This is to avoid developing potential in any part that might discharge and cause shock to you first of all, or damage sensitive electronics. The resistance of the +5v power supply on the amc1280usb and the ground is small, and that's you can measure it on the motor shaft, but that doesn't mean it's shorting. It's low impedance and won't carry any current with it to the motor casing. One of the tests I do to verify that the 24v digital inputs are not leaking is to measure the 24v connector on the 6dof ext board with no 24v supply connected to it. I expect to measure 4v on it with the amc1280usb powered from the usb. Yes that's right! It outputs 4v on the 24v input connector! But it's totally normal operation, as that's very low impedance feedback from the darlington transistors array chips that handles the 24v digital signals. But when I connect the 24v to the 6dof ext board, it sums back to 24v total as the 24v supply has much higher impedance. To conclude it's not easy to isolate the DC and AC grounds without making things worst in terms of signals. Especially the analog signals, need a solid common ground point for reference. Also if you use shielding on the analog wires, you should connect the shield to the ground ONLY on the amc1280usb side for the analog sensors, and ONLY on the 6DOF ext side for the 0-10v analog out signals. This will fix any remaining impedance related noise, as it acts as part of the filtering (cable resistance length by capacitance of the shield). Thanks Thanos |
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Post by paulg100 on Jan 14, 2017 18:07:11 GMT
OK thanks for the detailed reply, it gives me some more things to look at. Not sure theres much else I can do, I cant think of any areas where the wiring is at fault. Fingers crossed the AEAT sensors will solve the issue, I did start designing a mount and gearing to 3D print but if your adding software reduction then that will save me a lot of time and printing so ill wait for that.  Thanks |
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Post by tronicgr on Jan 14, 2017 18:12:16 GMT
Your design looks good! But as you said, it will take lots of printing and still then after some use it might develop backlash as it wears. Direct connection of the sensor is always better.  |
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Post by paulg100 on Jan 20, 2017 12:52:51 GMT
Something exciting just arrived  Have a couple of the aeat sensors at home with picoblade prewired cables ready to go and mk1 sensor mount ready to print. Will solder the headers on tomorrow and hopefully have something to report by end of weekend. Have some cat7 network cable im planning to use to extend the sensor cables to cabinet. Praying this sorts out the interference problems im having or im out of ideas!! |
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Post by tronicgr on Jan 20, 2017 15:13:28 GMT
Something exciting just arrived Have a couple of the aeat sensors at home with picoblade prewired cables ready to go and mk1 sensor mount ready to print. Will solder the headers on tomorrow and hopefully have something to report by end of weekend. Have some cat7 network cable im planning to use to extend the sensor cables to cabinet. Praying this sorts out the interference problems im having or im out of ideas!! The pcbs look great. Perhaps you want to share the OSHpark order for others to order easily the same boards without having to go through sending the Gerber files. The digital sensors are much better in terms of EMI noise. I'm sure you will not have issues with them. Thanks Thanos |
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Post by paulg100 on Jan 20, 2017 15:57:38 GMT
Sure Link for ordering board here. Thanks for providing the files Thanos.
Price including shipping was about $8.50 for all 3 (minimum order) including shipping. time from order to delivery to UK was about 3 weeks. |
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Post by paulg100 on Jan 21, 2017 14:57:25 GMT
OK boards done and sensors working fine.  Got a bit ahead of myself as I cant really test on sim until the new firmware with software reduction is complete. In the mean time ill keep working on new design for modified sensor mount and new cables so its ready to go when firmware's finished. Over to you Thanos |
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Post by tronicgr on Jan 23, 2017 15:05:46 GMT
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Post by paulg100 on Jan 23, 2017 17:37:28 GMT
Great!
I got 1 sensor/motor hooked up last night and i dont want to speak to soon..... but it looks really promising.
Its the first time ive been able to get the system to consistently forward/home and reverse/home and have the VFD hit home with no activity on the "run" light of VFD and absolutely no jitter, even with start frequency at 0.5hz.
The real test is when more of the VFDS are hooked up as this is when emi overwhelms the old sensors.
I have the final 4 sensors and more cat7 cable ordered so hoping to get the rest set up this weekend.
ill give the new FW a test tonight at least on the one i have rigged up and report back,
Thanks.
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Post by paulg100 on Jan 23, 2017 22:20:30 GMT
OK new firmware tested, 180 range appears to be working correctly.
Can't test fully until all motors are hooked up but looks good, will report back as soon as I get this done.
Thanks
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