Putting the Rotorcraft/Accelerometer Question to Rest

There has been an ongoing discussion/debate about whether accelerometers are actually useful for attitude estimation on flying rotorcraft (quadrotors, in particular).  The simple, one sentence answer is "yes, they are."

However, the accelerometer measurements are non-intuitive.  If the estimation algorithm uses the accelerometers incorrectly (which is, incidentally, the norm on hobby and even some professional aircraft) then there will be significant errors.

There is some good literature available now that describes the problem.  Martin and Salaun published  a very good paper describing quadrotor flight dynamics.  I also just finished my MS thesis, wherein I address the subject in detail.

http://cas.ensmp.fr/~petit/forFC/PhM/2010/MartiS2010ICRA.pdf

In my thesis (the last link), Chapter 5 is what you'll want to look at.

master.pdf

Replies

• Thanks for your helpful post Caleb. Would you possibly know an answer to the following question:

Attitude estimation with ONLY 3axis ACCELEROMETERS. and nothing else, based on a lowpass filter? where can I find an opensource way to do this?

cheers!

Alex

• Developer

Hi Caleb,

Nice analysis.  Of course there is always more work to be done...    But it looks like a nice step in the right direction.

You appear to have an error in formula 5.15.  Fortunately it does not appear to carry forward anywhere.

I can follow the math but cannot intuitively see how the LPF filter model corrects the phase lag between the accelerometer estimated and actual angles.  Do you have an intuitive understanding of this that you can put in words?

• Great stuff Caleb! Thanks for sharing.
• Thanks Caleb for your great work and for being willing to share it with us.

FYI, Salaun's PhD thesis is also available (its mostly in English - don't be fooled by the first few pages)

http://pastel.archives-ouvertes.fr/docs/00/55/44/37/PDF/PhD_Thesis_...

- Roy

• Thanks for your work and sharing it with others Caleb. BYU's paper's style is always nice to read.

Activity

Practice virtual race this Saturday; the real thing will be on Oct 3 https://www.meetup.com/DIYRobocars/
Wednesday
Derrick Davies liked lisa TDrones's profile
Wednesday
Monday
RT @SahikaGenc: AWS DeepRacer & Hot Wheels Track https://youtu.be/4H0Ei07RdR4 via @YouTube
Sep 14
Sep 8
RT @davsca1: We are releasing the code of our Fisher Information Field, the first dedicated map for perception-aware planning that is >10x…
Sep 8
RT @SmallpixelCar: How this works: 1)object detection to find cones in single camera image, 30 frames/sec on @NVIDIAEmbedded Xavier. 2)comp…
Sep 8
RT @SmallpixelCar: Use two color cones to guide the robocar. No map needed, on onsite training needed. Just place the cones and it will fol…
Sep 7
RT @roboton_io: Great to see http://roboton.io running at 60fps on the cheapest #chromebook we could find! #edtech #robotics #educat…
Sep 3
RT @openmvcam: Crazy in-depth article about using the OpenMV Cam for Astrophotography: https://github.com/frank26080115/OpemMV-Astrophotography-Gear https://t.co/BPoK9QDEwS
Sep 3