UAV Challenge Medical Express rules have been released.

The UAV Challenge Medical Express rules have been released.

The Mission for 2016:

"Outback Joe is at his property in remote Queensland, Australia and has been feeling unwell. He has had a remote consultation with his doctor using video conferencing, and his doctor has requested some blood tests be done as soon as possible. Joe is well prepared, has a home sample taking kit, and has taken his blood sample. The challenge is now to get the blood sample to the lab. Joe’s property is very remote and to make matters worse, it has been cut off by floodwaters.

Teams are invited to attempt to retrieve a blood sample from the remote Outback Joe and return it to base where medical staff will be waiting to analyse it. Teams must deploy unmanned aircraft to Joe’s location, and then return a sample bottle from him utilising a remote landing and takeoff site close to him. They must complete all of this within one hour."

Documentation can be found here:

Rules PDF here: https://docs.google.com/file/d/0B5JgqjkRDqw8dTllN085ZTJyNjQ/edit

Site: http://uavchallenge.org/medical-express/

Challenge FAQ: http://uavchallenge.org/medical-express/medical-express-faq/

Brief overview of the 2016 OBC rules:

Two aircraft are allowed that can detach/reattach to eachother > one as retrieval aircraft and one for support > both can be airborne at the same time
Range required +40km but no more than 60km through "bent" geofenced transit corridor - waypoints will likely backtrack to get the total distance, but will be at least 250m apart. (see FAQ)
Flight must not take longer than one hour so the airframe must be able to achieve roughly 90-100kmh average, as well as be VTOL or STOL (!)
The RF Link range required is approximately 10km (3-4G Mobile and Satellite comms allowed - safety case req. for landing zone etc)
1500ft AGL altitude restriction
25knot average wind over 10 minutes will cancel the event (which is higher than last time)
Joe GPS coordinates that are provided are within 100m of Joe. One must locate him and land no closer than 30m, but no further away from Joe than 80m - distance away is scored at 2 points per meter - Joe has lost his colorful shirt but kept his jean pants on - phew!
payload to be picked up is 20x100mm and no more than 100g and must be returned intact back to base.
aircraft must remain motionless for 1 minute after landing near Joe before Joe will approach to place payload - Takeoff Arm switch is required by Joe at pickup location with one minute takeoff delay after activation
Biggest points are for delivering intact sample back to base
Only the top 20 ranking teams through D1-D3 will get to go (based on paperwork, flight logs and videos) - That will be tough
Might not be at Kingaroy this time...

No specifics are given to the makeup of the Joe takeoff landing site or base site, apart from that it will "impede low glideslope landings". So this could allow something like a Skywalker X8 with a quadcopter strapped underneath to launch and fly to location, identify and locate Joe exactly, then detach the quad for payload retrieval, while the X8 stays above the landing zone as RF relay until quad is released to takeoff, then both can head back with the X8 arriving first and possibly landing with a parachute and then the quad with payload some minutes later. A single VTOL might be nice but you'd have to land/takeoff blind without RF link. Helicopters welcome.

Shouldn't be too hard.... I think I have the gear for that here already. Time to dig out old Tinker Bell and send her back to get Joe! ;-)

JB, I think the algorithms would do OK with the pusher as-is. If you were in Loiter, and engaged the pusher such that the Pixhawk was not aware of what is going on, it would basically behave as if there was a strong wind. It would pitch up the nose, aligning the lifting thrusters to balance against the thrust of the pusher.

Actually case in point: Tradhelis already do this. The tail rotor generates a sideways thrust. In Loiter, the controller automatically rolls the aircraft right a little to counter it. There is nothing in the code to counter this. The only issue is that, it assumes it is wind, and basically fixed in earth-frame. If you rotate quickly 180°, there is a slight instability, as the thrust is now in the same direction it had developed a lean. It takes a little time for the algorithm to rebalance. This is a complete non-issue in operation mind you. Just stating, the effect is there.

I do think that to do this properly, you would want to modify the code such that demands for forward acceleration are fed to the thruster motor instead of requesting pitch from the airframe. And I actually don't think it would be very hard.

This is part of moving towards incorporating logic for hybrid aircraft like tilt-rotors, etc.

Speaking of, that's something else to investigate: a tilt-rotor quadcopter. Though I seriously expect that a quad with a pusher motor would be simpler and more efficient.

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Comments

Rob_Lefebvre March 23, 2015 at 1:13pm

JB, I don't see why alt hold wouldn't work. Works fine on Helicopters, even when pulling back from high speed where, in Stab mode they pull 6G's if you do nothing with the collective. In Alt_Hold, nothing, it just manages it. Maybe it just needs to be tuned in Gary's case? I'm not sure. I'm not saying Gary didn't have a problem, I just wouldn't expect that, I assume it's fixable.

I can see what I can do for collaboration. I might be interested in working on the code, but we'd have to get Randy to accept the concept first or else it will never make it into Master. I think this sort of change is needed to allow usage of compound systems, such as transitional VTOL, etc.

I'd also like to build something like a Eurocopter X3, which would need similar.
Fredrik Hedberg March 23, 2015 at 8:16am

JB,

Yes. The pull-requests uses the booster for forward acceleration after a specific (configurable) forward pitch has been request, and replaces excess pitch with lateral thrust. As Gary mentions it's very important that the thruster is mounted in the center-line of the vehicle at the configure forward pitch.
JB March 23, 2015 at 8:08am

Thx for the info Fredrik.

Have you already tried a pusher quad with this?
Fredrik Hedberg March 23, 2015 at 7:37am

JB, Gary, Rob,

There's a pull-request with support for pusher props at https://github.com/diydrones/ardupilot/pull/1932. The implementation is somewhat naïve but I think works decently as a first step. Haven't made any real world benchmarks with respect to added range v additional weight, but would be interesting if any of you have time to do it.
JB March 23, 2015 at 7:29am

Thx a bunch Rob

That's what I wanted to hear! ;-)

I'll see if can put something together this weekend to test and get back to you with the results. How will it work with altitude hold? Do you think that it will maintain altitude whilst in pusher mode, instead of gaining altitude like Gary experienced? I'm thinking of maybe intentionally letting the quad props autorotate somewhat, so turn it into a bit of a hybrid pusher/quad/gyrocopter.

Are you interested in collaborating on developing an airframe for the challenge? If so I'd like to enact your suggestion to make our own "thread" and would start our own google group or something to manage the discussion and information etc. and possibly setup a game plan. Only if you're interested and have some spare time though, no pressure from here. It does cost some time and effort these things. I know that too well personally from last time! ;-)
Rob_Lefebvre March 23, 2015 at 6:54am

JB, I think the algorithms would do OK with the pusher as-is. If you were in Loiter, and engaged the pusher such that the Pixhawk was not aware of what is going on, it would basically behave as if there was a strong wind. It would pitch up the nose, aligning the lifting thrusters to balance against the thrust of the pusher.

Actually case in point: Tradhelis already do this. The tail rotor generates a sideways thrust. In Loiter, the controller automatically rolls the aircraft right a little to counter it. There is nothing in the code to counter this. The only issue is that, it assumes it is wind, and basically fixed in earth-frame. If you rotate quickly 180°, there is a slight instability, as the thrust is now in the same direction it had developed a lean. It takes a little time for the algorithm to rebalance. This is a complete non-issue in operation mind you. Just stating, the effect is there.

I do think that to do this properly, you would want to modify the code such that demands for forward acceleration are fed to the thruster motor instead of requesting pitch from the airframe. And I actually don't think it would be very hard.

This is part of moving towards incorporating logic for hybrid aircraft like tilt-rotors, etc.

Speaking of, that's something else to investigate: a tilt-rotor quadcopter. Though I seriously expect that a quad with a pusher motor would be simpler and more efficient.
JB March 22, 2015 at 10:54pm

Thx Gary.

I'm pretty keen on trying it out to see how good it is. How did you control the thrust of the pusher? Did you just use a separate RC channel? I'm wondering if altitude hold would work with the PXH to maintain level flight? Or will the PXH go spastic because of the accelerometers are trying to make sense of the acceleration from the pusher? On the one from the GPS perspective it's like flying in high wind, but the other sensors might not like it and try to compensate. I have a 250 quad with PXH I was thinking of using to try it out. I'll try to mount the pusher inline with the prop centers.

Regards

JB
Gary McCray March 22, 2015 at 5:09pm

Actually built a little quad with a pusher prop a couple years ago, learned a couple of things.

1. The pusher prop center definitely needs to be directly aligned with the lift prop centers (the off angle thrust produces way too much pitch change other wise).

2. Not surprisingly all things being equal, the copter tries very hard to climb while you are using the horizontal thruster from the extra lift generated across the lift props.

I am sure that some appropriate routines could be written for the Pixhawk that would automatically reduce thrust and adjust pitch as necessary.

My experience is that you could very possibly end up with noticeably increased efficiency (for a given distance) versus a conventional quadcopter because the forward thrust produced by the horizontal motor actually decreases the thrust requirement of the vertical motors quite a lot (acting more like a gyrocopter).

Of course you would have to experiment to see if you could really get a significant endurance or range gain, but I'm betting you could.
Tom Gyllenhammar March 22, 2015 at 2:39pm

That's one large bloodsample! Maybe delivery of emergency drugs would be a more possible future scenario. Like sending oral corticosteroids to a stranded hiker with risk of anafylactic chock.
Daniel Wibbing March 22, 2015 at 12:13pm

JB,

ah, ok, you mean a hybrid airship that is heaver than air. ObliX is not like that.

Curious for your PM. ;)

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