Sine wave track for inductive position sensing

[buzmeg]

What’s the best way to lay out a sine wave in metal in KiCad (application: inductive position sensing)?

I can create a lot of straight tracks; I can plot arcs; I can use the new splines. I can dial the error down as far as I want, but that will obviously generate a lot of elements and all of the attendant problems that go along with that.

Which one is likely to give me the best results when I have to generate Gerbers for JLCPCB?

Thanks.

[dtreffenstaedt]

With really complex geometries it might be easiest to draw the geometry in some other program that suits you best, export it as vector graphics file, then import that into KiCad through File->Import->Graphics.

It will be imported as graphical shape. You can choose to assign a net to this shape, or convert it to tracks or zones depending on your specific needs.

[nickmBY]

Can’t help you with your question, but the background of your question is very interesting for me.

Do you have anything to read for me about this method?

[Shack]

This subject has been discussed a few times before

Code to write sine/cosine curves for angle sensor

Yep I found those Zettlex products first and have a folder of all the useful images of them I could find. Here’s one showing the active board which has a more regular pattern. [INMOCO258_Ultra_Incoder_series_expanded_pic1_PR6237_35767] If anyone could figure out how they work, this code could be adapted to make those patterns. But they are very serious about their patents so I was glad to find the Renesas! It seems with the renesas you can do arbitrarily high pole counts and get more resolut…

How to route sine/cosine patterns for an angle sensor?

Have you noticed that Renesas has some “Inductive Coil Design Tool Software” for designing the PCB sine curves? [image] Source: https://www.renesas.com/us/en/products/sensor-products/position-sensors/ips2200-inductive-position-sensor-high-speed-motor-commutation KiCad-nightly V5.99 has an importer for altium files, but it’s hidden in some way because it’s not ready yet. However, if that software can generate Gerber files, then you can back-import them into a regular KiCad project with KiCad…

A pretty cool script was also made for it.

GitHub - sequoia-hope/induction_encoder: python scripts and other files to...

[buzmeg]

Inductive position sensing? TU Graz has a nice video about it:

Inductive Positions Sensors: Fundamentals and Applications by Dipl.-HTL-Ing. Josef Janisch

CAUTION: There is a lot of “woo” around these things. You can use all manner of patterns and layouts to get ever more accuracy at the expense of vastly more complication. There are a lot of PhD theses about this stuff.

In addition, there is also a lot of weirdness in the layouts that results from using two layers (these things are heavily targeted at automotive) which causes a lot of imbalance because the separation between copper is 1.6mm or so. If you are willing to use 4 layers then your separation is only 0.2mm and a 6 layer board would only be 0.1mm and the layout is a lot less problematic.

[nickmBY]

Thank you!
This vidoe (only started to watch it) is most helpful. It also answered (the unasked) question about the sinusoidal tracks that puzzled me most.

I’m in the middle of developing a multi channel, multi protocol positional interface. And a sin/cos-interface is on the list to (IC-haus).

BTW: You can order 0.4 mm double sided PCBs. JLCPCB offers them at a small additional cost. 0.6 mm (IIRC) at no extra cost. Yes, still more than 0.1 mm.

Sorry for the distraction of the subject

[Mineotopia]

We wrote an addon to create coils in KiCad - maybe this is helpful for you as well: GitHub - DIaLOGIKa-GmbH/kicad-coil-creator: Generates PCB coils for KiCad