West Coast UAV's Deliverable 2 for the 2016 Medical Express Challenge

West Coast UAV is pleased to have completed the Deliverable 2 Technical Report and submitted this to the competition organisers.

This report details the our UAV systems that will be used the complete the mission and our risk management approach.

The team has put in a lot of work to get to this stage. Our key achievements have been:

  • Developing and testing a multi-point comms network to allow over-the-horizon communications to our retrieval aircraft,
  • Implementing a system to reverse the thrust of our retrieval aircraft so that it can achieve a very steep glide-slope and land within a tight space,
  • Tested multiple configurations of aircraft such that the retrieval aircraft can take-off in a short distance, whilst maintaining high-airspeeds and efficient cruise.

You can read our full report WestCoastUAV Deliverable 2 and read our blog at westcoastuav.org

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Comment by Tom Pittenger on April 14, 2016 at 5:15pm

Nice video! I like the Reverse Thrust, are you doing that on ArduPlane?

Comment by Ben Dellar on April 14, 2016 at 7:52pm

Hi Tom, the reverse thrust is currently implemented using a micro-controller in the throttle loop that monitors airspeed and altitude and applies it as needed. We will likely be switching to ArduPlane reverse thrust as we develop further to simplify hardware now that it is supported.

Comment by Tom Pittenger on April 14, 2016 at 8:01pm
Well, I wrote the reverse thrust stuff so feel free to ping me if you have any questions about it!

Comment by Ben Dellar on April 14, 2016 at 8:12pm

Ah  awesome - we may hit you up yeah, thanks for the offer. My understanding is that subject to the USE_REV_THRUST bitmask the TECS controller will use reverse thrust intelligently to manage energy during high glide-slope descents? Is that the right summary? Does it stop using reverse thrust at a certain altitude (to avoid prop strike on touchdown)?

Comment by Tom Pittenger on April 14, 2016 at 8:40pm
There's more to it, check the plane landing wiki for details.

Comment by Tom Pittenger on April 15, 2016 at 12:41am

and yes, it stops the prop in the final stage so you don't strike the ground

Comment by JB on April 15, 2016 at 3:56am

HI Tom

I've been very keen to try out the reverse thrust capabilities for a while, but have been caught up in quadplane instead until now.

I was actually hoping to achieve a more tightly integrated operation of the forward motor into the quad propulsion setup rather than just transitioning. For example by using the forward motor on the quadplane to maintain position and move forwards, rather than quad pitching forwards, as well as some combination moves like high alpha climbouts and steep reverse thrust approaches with ground proximity flare into quad, using both quad and forward motors. 

Can you think of a way that might be possible to integrate in Arduplane? The main reason is to avoid battery consumption and the risk of instability whilst hovering in high wind. The less time it takes to transition and VTOL the less it is exposed, and higher approach/departure speeds provide better wind penetration.

What do you think, would appreciate any feedback. Thx.

Comment by Tom Pittenger on April 15, 2016 at 10:49am


forward motor into the quad propulsion setup

In ArduCopter this is called "Fast-Forward" and there's been work on it but I'm not sure if it ever made it into master. No work on ArduPlane that I know of.

steep reverse thrust approaches with ground proximity flare into quad

I like the sound of that, "flare into quad". This seems pretty awesome but probably very hard to do automatically. Quadplane is not as stable as normal quad mainly due to the huge moment-of-inertia involved. Something to keep in mind though.

Comment by JB on April 16, 2016 at 9:39am

Thanks Tom!

Fast Forward sounds like what I want then! I'll have to look into it. I'm assuming it's a quad with horizontal pusher/tractor prop? You wouldn't happen to have any links with info on it?

In regards to "Flare into quad", I'm not using, or am expecting to use a large and cumbersome quadplane for this. Currently we're running a sub 2kg quadplane with over 5kg of quad thrust, the main wings with spars only weigh 150g each. So not much more mass than any other 2kg quad. Roll and pitch control are nearly as good as a low performance type quad, the biggest issue is yaw (which we've switched off for wind feathering because of the wings) that is always loading up just two motors and not changing heading much at all, so we're going to use a v-tail next for more yaw authority. I'm not expecting "Harrier jump jet" type performance by combining them, just a more dynamic and quadplane specific VTOL. Heli's can do it "naturally" by washing of rotor inertia on flare, and I was hoping to achieve a similar landing profile, but with quad thrust. In our next model I was thinking of halving the wing area again as we don't have to worry about stall speeds anymore with quadplanes....it's weird but seems to work well if you use them like that. ;-)


Comment by Andrew Tridgell on April 16, 2016 at 3:09pm

actually you can do fwd thrust on ArduPilot quadplane now. Have a go at FBWA or CRUISE mode at low throttle. The plane will fly around using fwd motor for fwd thrust and vertical for lift. It will stay level. Yaw is done with quad motors.

For CRUISE mode the key is to set ARSP_FBW_MIN nice and low - say 1m/s.

It also works in AUTO mode. Just use DO_SET_SPEED to lower the target speed low enough and it will start doing this. You do need an airspeed sensor though.


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