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Post by hexpod on Oct 15, 2016 9:23:42 GMT
"With current resolution of the ADC, you can achieve 0.175 degrees steps of angle if you are using 180 degrees sensor."
are you talking about AMC analog-digital converter? I thought it was 16 bit capable.
cheers
Its selectable resolution from 10bit to 16bit, but the more you increase the resolution, the slower the controller gets as it takes multiple readings to achieve the higher resolution. I guess, oversample ADC scale goes from 1 (10 bit) to 16 (16 bit) Which number on this scale (1-16) corresponds to 12 and 14 bit resolution?
"it takes multiple readings to achieve the higher resolution"
If you increase the oversampling, it will not deliver a true 12 or 14bit resolution, it can only read several times 10 bit, to improve accuracy.
Did I got it right?
cheers
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Post by hexpod on Oct 15, 2016 21:31:50 GMT
From another series of stupid questions...
needs the AMC to be extra grounded? or the ground from the usb is enough?
cheers
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Post by hexpod on Oct 15, 2016 23:24:38 GMT
"I asked them for samples and prices for the vert-X 1300 with SSI interface"
It seams that the vert-X 1300 has a resolution of 0.1deg.
If we want to go higher (0.02deg.) we have to choose the vert-X 1600 or Vert-X 2100
It could be that the resolution is related to the interface SSI-0.1 SPI-0.02
It maybe worth the hassle
Please keep us posted...
cheers
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Post by tronicgr on Oct 15, 2016 23:43:37 GMT
Its selectable resolution from 10bit to 16bit, but the more you increase the resolution, the slower the controller gets as it takes multiple readings to achieve the higher resolution. I guess, oversample ADC scale goes from 1 (10 bit) to 16 (16 bit) Which number on this scale (1-16) corresponds to 12 and 14 bit resolution?
"it takes multiple readings to achieve the higher resolution"
If you increase the oversampling, it will not deliver a true 12 or 14bit resolution, it can only read several times 10 bit, to improve accuracy.
Did I got it right?
cheers
To answer your question: www.embedded.com/design/mcus-processors-and-socs/4008894/Oversampling-with-averaging-to-increase-ADC-resolution
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Post by tronicgr on Oct 15, 2016 23:47:13 GMT
From another series of stupid questions...
needs the AMC to be extra grounded? or the ground from the usb is enough?
cheers
If you need better ground connection, you should connect a known good ground to the ground pins on the terminal of the 6dof ext board. This is more important for VFD applications that use analog signal that is delivered by this extension board. The AMC1280usb itself has good grounding via the computer USB she'll. Thanks Thanos
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Post by tronicgr on Oct 15, 2016 23:55:04 GMT
"I asked them for samples and prices for the vert-X 1300 with SSI interface"
It seams that the vert-X 1300 has a resolution of 0.1deg.
If we want to go higher (0.02deg.) we have to choose the vert-X 1600 or Vert-X 2100
It could be that the resolution is related to the interface SSI-0.1 SPI-0.02
It maybe worth the hassle
Please keep us posted...
cheers I'll ask them about the other models as well when they get back with me. The existing resolution for 180 degrees measurement is 0.175 degrees for ADC with BI-TECHNOLOGIES sensors... but the noise! The SSI is still digital and has same 14bit resolution as SPI. Where did you see this difference?
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Post by hexpod on Oct 16, 2016 10:01:21 GMT
"The SSI is still digital and has same 14bit resolution as SPI. Where did you see this difference?"
You are for sure right, ignore it.
cheers
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Post by hexpod on Oct 16, 2016 10:19:20 GMT
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Post by tronicgr on Oct 16, 2016 15:15:47 GMT
Here is a simplified code of how I do the oversampling: For Nrepeat = 1 To Ntimes Nsample = Getadc(0) Sumx = Sumx + Nsample Next Oversample = Sumx / Ntimes I hope that helps get a clear picture of whats going on on the background. Thanks Thanos
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Post by hexpod on Oct 16, 2016 17:48:36 GMT
"I hope that helps get a clear picture of whats going on on the background."
Thank you for your explanations and patience.
Let's hope switching to digital will give us a substantial improvement.
Good luck
cheers.
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Post by hexpod on Oct 17, 2016 10:50:13 GMT
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Post by tronicgr on Oct 17, 2016 18:07:29 GMT
Definitely, this could improve the noise issues, given that you use shielded audio cable, with the shield connected only on the ground on the amc1280usb side. Thanks Thanos
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Post by hexpod on Oct 17, 2016 18:29:42 GMT
"Definitely, this could improve the noise issues, given that you use shielded audio cable, with the shield connected only on the ground on the amc1280usb side."
Great, I will try!
Would you mount it on the sensor side or AMC side? How far from the end?
cheers
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Post by paulg100 on Oct 17, 2016 20:40:22 GMT
I have experimented with multiple ferrite cores like the link (official TDK ones so not cheap knockoff', the cheaper ones are fakes and not as effective so I gather)
Ive tried some on motors and some on sensors. I used an oscilloscope to check for improvement and could not see any noticeable gain. There was no benefit to real world performance either.
MAYBE it will be more effective if I had enough for every sensor, at the moment I only have 2 or 3 sensors fitted with them on, both at sensor end and at AMC end.
If you still by some, please keep us posted on your results so we can compare, thanks.
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Post by hexpod on Oct 22, 2016 19:01:36 GMT
I'm not sure if it is the same issue. All i know that after many hours of experimenting with PID , in order to improve response and achieve better repeatability of position. What "P" value you've reached without "hunting" on the arms?? In my case I can not get clean response with value higher than 15.
As I made now all possible efforts to isolate the sensors from noise, I am searching for a parameter which would aloud me to go with a higher "P"
It is really easy to get lost in this jungle of parameters.
cheers
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