7x24 Sensor Package Moving Back and Forth on ~100m Track

[gman09]

Functional Application Overview:
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I am trying to work out an application problem were a small sensor package, perhaps 1-2 lbs around the size of a thick paperback book, moves back and forth on a 100 meter straight track at slow speeds (a foot or two per second, typically), collecting various readings on the environment, including for sample some visual data and some changes in object proximity data, and sends this information back to a central system via WiFi or some other wireless means. Sensor pack, ignoring propulsion issues, is perhaps a 5-20 watt draw. The track would be outdoors but would not have direct explore to rain or much wind, IP55 kind of stuff - think being under a roof, but in open air. We are trying to keep track cost down under $5-$10/foot, if possible. Operation would be 7x24, and ideally it should require maintenance no more often than 2 times per year. It is very desirable that it be very quiet, which is what suggested a partial magnetic solutions (combined with some appropriate mechanical support) might be a really good fit, either for lift, propulsion, or both.

My expertise is in the wireless sensor package design and the central system, not in magnet systems or mechanical engineering. But I have a sense that the decrease in price over the last few years of neodymium magnets, some cleverness in deployment like the the Halbach Array and/or Halbach Array & Inductrack, some newer inductive charging systems like WiTricity, some mix of these things, could give me a low maintenance, very quiet solution that would not have been available even just a few years back. Plus, extreme coolness factor!

But since I do not know what I am talking about, I figured I'd toss it out there and see what some people with real experience think is a good way to handle it. I am not looking for a pure magnetic levitation solution, I figure some partial touch with a wheel or bearing or two will be needed to get it stable in all 3 planes.

Hope is to build hundreds of these guys, if it works.

The Issues I See Just Now That Confuse Me:
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What a good choice for track material that would help keep cost down, but still be reliable and stable?
Better to hang from the track, or ride on it?
Should the track carry power of some kind, and is it practical to draw that power inductive into the moving sensor pack, or would it be better to move the pack every so often to an dedicated inductive charging station (or is there yet another smart way to power the thing?)
If neodymium permanent magnets are part of the solution, are they stable over a multi year time frame outdoors?

Anyone have some ideas about some good and creative ways to approach the application are greatly appreciated.

- Cheers,

Michael

 

[MagMike]

I'd recommend working with an existing linear drive manufacturer. Most of the designs I have seen involve a track consisting of a linear array of magnets, with the energized coils on the stage. This would allow them to make the track as long as you want. The limiting issue would be running power to the stage and/or sensor pack.

As long as they are protected from corrosion & high temperatures, neodymium permanent magnets will be stable over a multi year time frame.

 

[gman09]

Mike,

Thanks for the reply!

That brings up two questions:

1. Can you suggest one or a few existing linear drive manufacturers whose technology might be a good fit here?

2. I am a bit worried about cost spiraling far beyond the $5-$10 per foot range with existing linear drive manufacturers (could be a hopeless goal, of course). Have you any feel for how 'high end' this kind of solution turns out to be?

Thanks,

- Michael

 

[MagMike]

I haven't worked with a linear drive manufacturer in many years, so my contacts would be too dated. I'd recommend doing a search in Google.

Because it's been too long, I don't have a feel for the costs either.

Sorry, can't be of too much help.

 

[gman09]

I have looked a little at a few suppliers (THK, BAHR, MagneMotion). All seem to be focused on material handling applications, to be engineering handle 50x the weight I am targeting, to not be optimized for high levels of silence, and to cost far more than the target for this application.

I am really trying to get to a high levels first-engineering principles discussion of how to tackle this application.

Anyone who ever thought through anything remotely similar able to jump in?

- Michael