OFFICIAL - 2011 UAV Outback Challenge Forum - Page 13 - RC Groups
Shop our Airplanes Products Drone Products Sales
Thread Tools
This thread is privately moderated by Mick Molloy, who may elect to delete unwanted replies.
Jul 09, 2011, 03:58 PM
Registered User

I have a few questions, in working on our D1 I have a question on the implementation of the flight termination / gps fence etc.

Our autopilot is a Cloudcap Piccolo LT
Implemented in the autopilot software are the following

Loss of data link return to way point
Loss of data link and gps flight termination
Loss of GPS flight termination
Min / Max altitude flight termination
Outside GPS fence flight termination

There will be a separate board as required by the rules that monitors the status of the autopilot (for lockups / failure only) and the status of the RC link. This board can override all other commands and force the servos into the flight termination mode and is powered from the primary system batteries, with its own battery as a backup to those(via a diode). Is this a legal implementation? Specifically for most of the flight termination to be done on board the autopilot, and as a separate question for the power system to be implemented in that manner. I am not asking for design assistance, only weather the implementation of those features on the autopilot is sufficient according to the rules.

Also, would it be within the rules to allow the RC pilot to take command of the aircraft if the autopilot were to lock up, thus initiating a flight termination within sight of the airport?

Justin Stiltner
Virginia Tech Unmanned Systems Lab
Sign up now
to remove ads between posts
Jul 10, 2011, 09:56 AM
My other plane flies itself..
IClaudius's Avatar
Originally Posted by tridge
Our team has a question about the interpretation of the 3rd bullet in section 5.6, Flight Termination. We see the words "OVERRIDING any other onboard system" as still allowing for override by the pilot on the ground, using manual RC control, but that depends on the interpretation of "onboard system", so we would like to get confirmation that our interpretation is OK.

The reason we interpret it this way is twofold. First, we think that allowing for RC override while in visual range increases safety. For example, if a geofencing error occurs in the autopilot while it is still over the airfield then allowing for the pilot to try to bring the plane down well away from spectators seems like a safer option. This would only happen when the plane is in visual range, and the pilot judges that manually overriding using the RC transmitter is the safest course of action.

The second reason we think this interpretation is probably the right one is that we noticed that the block diagram of the Millswood failsafe device shows that RC override is possible even after flight termination is activated (the RC mux is the last mux in the chain). I think the Millswood device was given the OK in previous challenges, so that seems to support the interpretation that RC override is allowed.

Can you confirm that "onboard system" does not exclude the possibility of RC pilot manual override in case flight termination is activated?
Hi all,

just wondering if an official statement on the above has been received, as we have a similar concern over the interpretation of 5.5.1.

For example, given:
  • "immediate activation of the flight termination mode" is required on
  • "Loss of GPS position AND Loss of Data Link" and that this
  • "must be met for both autonomous or manual flight modes"

a strict interpretation would imply that if the aircraft is within visual range and under manual RC (e.g. non-autonomous take-off), and for some reason suffers a GPS and data loss link (or autopilot lockup, or...) then the flight termination system should be engaged. Which doesn't seem likely to be the actual intent.

Like the quoted poster, our interpretation is (at least for platforms where SAS is not required) that within visual range that manual RC control take precedence over the flight termination system, both on the basis of increased safety (i.e. allowing judicious use of manual control when in visual range during what would otherwise be a flight termination condition) and simply on the mere existence of section 5.4 detailing the UAV controller overrride.

Nevertheless, that specific use of "manual" in "must be met for both autonomous or manual flight modes" in section 5.5.1 remains a little incongruous to us, and as such an official clarification as to whether or not FTS takes precedence over manual control in all or selective cases would be appreciated.

Claudio - Team LOAF UAV
Jul 10, 2011, 10:15 AM
Registered User
TeamSAR_2011's Avatar
I would like answer(s) to Justin's question too

Although as I understand the Piccolo already has build in monitoring system so that when in lost comm situation, the uav will still maintain normal flight plan until the time out period is reached, at which time the uav can either terminate the flight on the spot, fly to a predetermined location and terminate, or fly to predetermined location and if comm is regained, the uav may be return to land normally or in manual external pilot mode.

If comm. can not be regain, the piccolo can autoland by itself

If the autopilot locks up then the uav will crash anyway

so the question is why do we need the board?
Jul 10, 2011, 10:24 AM
Registered User
TeamSAR_2011's Avatar
I would imagine in the event of the uav looses comm during external pilot (EP) mode even in visual range, the uav will automatically track the preloaded flight plan (usually an overhead flight pattern) and if comm can't be regained the uav may either terminates, flies to comm hold then terminates, or performs and autoland

If the uav looses comm and gps during EP control then it will terminate immediately which mean a crash right in front of everyone usually

If the autopilot locks up then the above will also happen

So are you requiring the extra board to monitor comm heart beat and also provide back up RC control and manual termination?
Jul 10, 2011, 06:56 PM
Registered User
Originally Posted by IClaudius
just wondering if an official statement on the above has been received, as we have a similar concern over the interpretation of 5.5.1.
We haven't received a reply from the organisers. Given how close we are to D1 being due I can only guess that the organisers might accept either interpretation for D1, and hopefully it will be clarified before D2.

Cheers, Tridge
Jul 10, 2011, 07:40 PM
Registered User
wanabigaplane's Avatar
IClaudius - no official statement has been received.
When looking at the functional diagram of the Millswood device we thought that RC would override any termination command. When looking at the circuit diagram, we discovered the truth of this is purely a function of the software, and we understand some contestants requested software changes with their purchase.
Since the most likely time we are likely to discover lack of comms coincident with faulty GPS cover is just after takeoff, we questioned the wisdom of crashing the aircraft while in the vicinity of the contestants and judges. However, considering D1 is a go/no go decision, and in the light of no official comment, deciding to not follow the strict interpretation of the rules might be courageous.
Jul 10, 2011, 11:13 PM
Suspended Account
One cool thing about D1 is there is no mention of a limit to the number of 6-page short technical reports you can submit. So why not just write up two or three and see which they accept?
Jul 11, 2011, 03:41 AM
Registered User
If the autopilot locks up then the uav will crash anyway
I do not think it is safe to assume that if the autopilot locks up, the aircraft will crash. It might, but it might also fly away, or do anything at all. It cannot be known with certainty what the behaviour will be, hence the requirement for flight termination to be managed by a separate device.
Last edited by Andrew Dunlop; Jul 11, 2011 at 04:24 AM.
Jul 11, 2011, 07:03 AM
Registered User
TeamSAR_2011's Avatar
Hi Andrew,

The thing is I don't think it will be any safer to have another piece of hardware sitting between the autopilot and the actuators.

I'm not saying that your board will fail but just like anything if it does fail while sitting in between the AP and the actuators then what happen? Can the fail safe board be automatically be by passed?
Jul 11, 2011, 08:24 AM
Registered User
Hi TeamSAR_2011,

My opinion doesn't really count, it's the organisers that you need to persuade :-)

But for what it's worth, I do agree that any device - including a flight termination device - can fail. However the probability of failure is not the same for all devices. An autopilot contains complex software and I am sure no manufacturer would claim their autopilot to be bug-free. A flight termination device is rather simple in comparison, and with a similar level of diligence on the part of the designers should have a far lower probability of failure.

So I would argue that the addition of a flight termination device adds the small probability of its own failure, but mitigates against the much larger probability of autopilot failure, and thus provides a net safety benefit.
Jul 11, 2011, 10:22 AM
Registered User
TeamSAR_2011's Avatar
Hi Andrew

I'm not making an argument with you - this is for everyone to read and for the organizer.

It's like even if you have 2 x Autopilot hooked up to a "magic box" so that if one fail the other take over. What if the "magic box" isn't so magical anymore?

I'm mainly in disagreement with the rules not your product. I think it's great that you make something like that to help us rectify the requirements.
Jul 12, 2011, 06:19 AM
Mueller Aviation
anthonyATteamMUROC's Avatar
Greeting Organizers
A question regarding length of Dev-1. Does the (max) 6 pages include a title page and table of contents; or would you rather we leave those out altogether? Yes, I know Dev-2 has those items, but by habit I include them.

Jul 12, 2011, 09:56 AM
Registered User
TeamSAR_2011's Avatar
We did our 6 pages including tittle and index - ah well we weren't sure either.
Jul 13, 2011, 12:48 AM
Mick Molloy's Avatar
quick stepin again for Mick, as he's on holidays.

D1 submission is a total of 6 pages - how you use those 6 pages is up to you. I believe it's due shortly, so I'm hoping many teams are well on their way to finalising their D1 submissions.

As for the other questions, I have copied these to all the tech committee members, and we are hoping to publish a response in the next couple of days. In the meantime, any other questions, please post them.


An updated version of the rules will be posted to the outback challenge website very soon (am hoping in the next day). I would strongly recommend that teams direct their attention to the failsafe section(s). One to take particular notice of : Once flight termination has been activate it is not allowed to be overridden by any means. This includes, all modes, Autonomous and Manual. We have split up slightly the failsafes explained for autonomous and manual modes to minimise misinterpretations.

Also, the option has always existed since the first competition many years ago, that teams are welcome to propose alternate flight termination systems (as required or necessary as per Section 5.6.1).


Last edited by Mick Molloy; Jul 18, 2011 at 06:30 AM. Reason: update
Jul 18, 2011, 04:21 PM
Registered User
Hi to all and the organizing team,
as the time to registration and D1 runs out I have to ask here if the contact form on the OutbackChallenge Homepage is working and how long it could take to receive an answer?
I sent a question there last week about the possibility for a group to participate in general but no reply yet...

If you got the message please respond to it via the adress given, otherwise is there another direct contact possible?



Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Uav challenge outback 2011 leogarabello Australian Electric Flight Association 1 Feb 08, 2011 09:33 PM
Contest OFFICIAL - 2010 UAV Outback Challenge Forum Mick Molloy UAV - Unmanned Aerial Vehicles 589 Feb 02, 2011 06:18 PM
Discussion UAV Outback Challenge ommadawn FPV Talk 0 Sep 25, 2010 02:37 AM
Contest UAV Challenge Outback Rescue 2009 - Official Thread Mick Molloy UAV - Unmanned Aerial Vehicles 720 Nov 19, 2009 12:42 PM