Archive | December 2012

UAV Project Summary

Since I started this blog, I have uploaded various bits on my progress and thought it prudent to do an update on where the project stands now.

In the startup post, I put up some goals for my project.  Though I did not meet everything, I am fairly satisfied that I exceeded some expectations that took the project into a different direction.

The UAV / FPV plane in it's current incarnation, sans the FPV gear.

The UAV / FPV plane in it’s current incarnation, sans the FPV gear.

Very Good Loiter time (1 – 2 hours)

I did not nearly make this target.  I did approach a theoretical time of around 40 minutes with my initial designs.  My current design is much heavier than anticipated with a much better payload than anticipated.  The “mission profile” has also changed from flying around using FPV, and staying in the air for a very long time, to shorter missions to cover an area with aerial photography.  With the more capable plane, I ended up reaching a practical limit of around 20 minutes.

Medium Range (3 – 5km)

Flight path retrieved from on-board telemetry and displayed in Google Earth.

Flight path retrieved from on-board telemetry and displayed in Google Earth.

This was an FPV target that I set.  Since the plane’s focus move to aerial photography, I sort of abandoned FPV and only added it near the end again as a fun element.  Even though I suspect that my FPV setup will reach at least half the target range, my 2.4GHz radio does not reach near that.  The best I managed so far was around 800m.  It seems as if I will have to switch to a long range radio setup if I want to go further.  Since the plane has a full autopilot, can cruise at around 40km/h for around 20 minutes, it has a theoretical operating range of around 6km.  I have however decided against letting the plane fly out of radio range and my fail-safe setting is to return to launch should I lose radio signal.

Pan / Tilt system for training the camera on a point of interest 

20120702-090206.jpg

Original Pan mounted camera and transmitter FPV back-pack.

This was achieved, but later removed.  Since the plane’s focus changed, I simplified the FPV setup to a back-pack that can be easily removed.

Waypoint and orbit functionality, leaving the pilot’s concentration on operating the camera and not flying the plane at those times.

Autopilot mission planner and live telemetry viewer.

Autopilot mission planner and live telemetry viewer.

This was achieved and exceeded.  The plane can take-off and fly fully autonomous.  A telemetry link is also present that enables the operator on the ground to direct the plane on a map.

Conclusion

3D model built from aerial photography of Pretoria Radio Flyers.

3D model built from aerial photography of Pretoria Radio Flyers.

Since the original project targets moved a bit, I’m quite happy at the results so far.  The plane performs very well as a cheap aerial photography platform.  The autopilot acts as a very good safety-net for starting off FPV flight.  I have given the controls to numerous people at the club to give them their first taste of FPV flying without real fear to the plane’s well-being.  With the autopilot in Fly By Wire mode it’s practically uncrashable if I pay at least a bit of attention to the person flying it (barring of-course malfunctions to equipment).

Way Forward

Digital Elevation Model built from aerial photography.

Digital Elevation Model built from aerial photography.

The biggest limitation of the current plane is the inefficient airframe.  It can carry a lot, but is very “draggy” and uses too much energy in cruise.  I really want to move to a more aerodynamic airframe.  Even though the current airframe can lift a lot, it’s internal space is really unusable to a big degree.

I am considering two airframes as a replacement:

finwing Universeye_Penuins Airplane 03

Finwing Hobbty Penguin

Finwing Hobby Penguin

This plane is built from the ground up as an FPV aircraft.  It also has a down looking window for a camera.  It gets good reviews from the community and friends using it.  Internal space is huge.

Pros:

    • Around the same size as the airframe I’m currently using, so I can re-use the current airframe’s equipment.
    • Efficient cruising
    • Lots of internal space
  • Easy to hand launch, or ground-takeoff
  • FPV ready

Cons:

  • I won’t be able to fit a bigger still camera than I’m using.
  • I won’t be able to fit a roll mount for the static camera for turn compensation.

Skywalker X-8

This is a HUGE flying wing with a LOT if internal space.  It gets very good reviews and is also personally recommended by a friend already using one for Aerial Photography.

Skywalker X8 Wing

Pros:

  • HUGE internal space that is easily accessible.
  • Can fit a bigger camera
  • Can fit a roll mount for the camera

Cons:

  • Needs beefier hardware than my current setup – need new motor and batteries.
  • Can be tricky to launch alone
  • Expensive

Due to cost, I’m leaning towards the Penguin as my replacement aircraft.

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APM Telemetry

I’ve had the question put to me whether the telemetry radio is really needed for the Autopilot. Though strictly it’s not required, I would strongly recommend to get the telemetry link with the Autopilot.

Here are some of the deciding factors for me:
1. Don’t have to plug in the plane every now and again to update a mission.
2. Updating and changing of missions while in the air (handy if it heads back to Pretoria while in Limpopo!)
3. You can fine-tune the autopilot while in the air. Carefully of course!
4. You can follow your aircraft on a map while it’s doing it’s job. Also handy to see how well it handles your mission, so that you can learn to plan missions better in the future.
5. Live HUD showing all kinds of handy info. Access to around 90 parameters that can be displayed live.
6. You can control the plane by sending it to a point on the map. Should you have a gimballed camera, you can also control that by pointing it to a point on the map (guided mode).

Below is a video (speeded up 10x) of a flight and what the telemetry looks like whilst in flight.