Replies to This Discussion

ModeratorPermalink Reply by Gary Mortimer on February 22, 2011 at 11:55am

Yes, because if your Arduinos fail or Xbees you have no redundant link.

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Permalink Reply by arbarnhart on February 22, 2011 at 1:10pm

 

The odd thing about this is that using the Arduinos as an alternative to traditional RC is fine and the first thing I am working on with respect to autonomy is actually an enhancement - heading back toward the takeoff location on loss of signal, based on GPS and compass readings. So it's only when it starts behaving better than a traditional RC that it would be considered not good enough...

Is there more detail somewhere that specifies redundancy or are you inferring it from what I quoted?

 

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ModeratorPermalink Reply by Sgt Ric on February 22, 2011 at 2:52pm

If you attempting to build in safety and redundancy to the level that the FAA (or whomever) would be satisfied with, let me assure you that that would be incredibly expensive!

 

The US Gov certification process has been explained before on this site, and involves an impossible amount of time and money.

 

P.S>  ReturnToHome is already built in to the ArduPilot.

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Permalink Reply by Erik Hatch on February 22, 2011 at 4:57pm

Sgt Ric,

What regulation in the CFR covers UAV/UAS ?

 

Erik

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Permalink Reply by arbarnhart on February 22, 2011 at 5:18pm

Sgt Ric,

 

No, I am not trying for certification. I was just trying to clarify the recreational guidelines. I do need to take a look at ArduPilot, but to start with I am using my own code that works on the car and boat. That code doesn't have elevation, but it has the GPS and compass input and bearing to seek calculation, compass monitoring in turns, communicatoin monitoring and hooks for other functions. Since the plane I am using to start with is a simple RET type, I pretty much have the R and the T. I am not trivializing what it will take to properly control the elevator, but that is a challenge I look forward to (and I have already found there is a sizable range where going fast climbs and going slower descends).

 

I am not sure my point was clear in the previous post. If I fly using my home built Tx/Rx to control the plane, I am certainly liable if I have a problem with it and cause some damage but I am not outside the law to use it as long as it works. But as soon as some autonomous feature is used, it sounds like I might be outside the regs even if it works perfectly and has adequate safeguards to cause no damage if it fails.

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Permalink Reply by Duane Brocious on February 22, 2011 at 7:00pm

In the USA, at the moment, recreational users "are to look to AC 91-57 for guidance".

AC 91-57 has been ignored for the last 30 years because of its "voluntary" nature.

Recreational sUAS/UAS users can pretty much do anything they want.

 

That is in the process of radically being changed.

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Permalink Reply by Duane Brocious on February 22, 2011 at 7:04pm

As for the radio, you need to follow FCC regulations.  a ham license may be required for anything not specified as RC for model aircraft and for the recreational FM/AM  frequencies you can only DIY 26Mhz stuff, however one of those 26Mhz frequencies allows for a 4watt output.

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Permalink Reply by arbarnhart on February 23, 2011 at 6:34am

I did some searching and can't find the regulation about that frequency in particular, but I did find one about 72 and some info on 2.7GHz for model aircraft, 27 and 49 for toys and 900 for consumer devices. The 315 and 434 stuff you can get off shelf gets a pass because of the low power (though I wonder about the Seeed Studio long range 434 pair). Circling back to my original question, though, this could put a real damper on the idea of calling a plane driven by data com as being RC at all. 

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Permalink Reply by Duane Brocious on February 23, 2011 at 8:00am

FCC regulations and information is available HERE

 

27.255 MHz @ 4 watts is more powerful than almost any other RC radio made today so I would hardly say it is used for toys.

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Permalink Reply by arbarnhart on February 23, 2011 at 9:26am

I followed that link to the discussion of the current sub part 95 and its link to the actual document and found the reference to using the 26/27 frequencies. Unlike the 72 frequencies, they are not restricted to just model airplanes and there is a warning about potential interference.

One interesting tidbit is that there is a specific exclusion about sending data on RC frequencies if that data is device control information (otherwise, data transmission on those frequencies is forbidden).

 

However, I keep going back to that vague statement of "manual control" and it seems like that as long as you can demonstrate that you are able to over ride what the plane is doing autonomously and make it do what you want then the requirement should be satisfied. I have not seen anything that specifically says the link to control it has to be redundant or even an R/C link at all (no, I don't plan on trying IR or some other tech, just pointing out that it doesn't seem to specifically say). I mean no disrespect to those who have opinions that it can be inferred from the statement or perhaps have seen other more specific documentation. Please point me toward that other specific information or explain your conclusion. I am obviously biased because I don't want to spend the extra money and put the extra weight on my plane.

 

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Permalink Reply by Duane Brocious on February 23, 2011 at 10:23am

The 26 Mhz bands are not used much today. The 4 watt band is probably going to be free and clear. As for "sending data" that means you can't transmit video or audio over it or use it for comuter networking etc. just radio control sigmals (which is still data but the FCC doesn't seem to understand computer technologies).

 

Hoppe that helps.

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