George Tarrant
  • Male
  • Bedfordshire
  • United Kingdom
Share

George Tarrant's Friends

  • Bruno de Oliveira Motter
  • SaadT
  • Michael Pursifull
  • Ben Carson
  • Simon Wunderlin
  • Jost Laznik
  • Gabriel Hugh Elkaim
  • kuxz
  • MarcS
  • Alex
  • Doug Weibel
  • Roy Brewer
  • Krzysztof Bosak
 

George Tarrant's Page

Profile Information

About Me:
I'm a graduate engineer and for many years I've been involved in guidance, navigation and control studies for research branches of the UK military.
Please tell us a bit about your UAV interest
I'm no longer involved with ther UK military and recently I've becomes interested in autopilots for small UAVs since (a) they sound interesting and (b)I might be able to "pull through" some of my military background into the civil field.
Hometown:
Maulden

George Tarrant's Blog

Fast-track PID lop setup

Posted on February 12, 2012 at 5:30am 8 Comments

Last August I posted a blog "New offer of help with tuning PID loops" putting forward the idea of applying control doublets to a fixed wing aircraft in flight and using the responses to capture stability derivatives and decide autopilot gains. At that time I only had simulation results and was seeking flight test data. I have since got hold of some flightt test data  and analysis confiorms that my processing concept does work.

The first step is to fit a model of the…

Continue

New offer of help with tuning PID loops

Posted on August 29, 2011 at 11:02am 14 Comments

I suspect my first method for tuning PID loops was not a great hit because it required 3-view drawings or photos of the aircraft plus inertia data all of which is a bit fiddly. I've now got a new method based on flying the aircraft and logging accelerometer and gyro outputs in response to elevator, rudder and aileron doublets. This method works well with simulated data and I'd like to try it on real data. If you are interested in this experiment, let me know your email address and I'll send…

Continue

Offer of help with tuning PID loops

Posted on July 20, 2011 at 11:35pm 4 Comments

Sorry, but I should have made clear that my autopilot design experience relates to fixed wing aircraft so I won't be able to help with rotary airframes.

I should also emphasise that the databse I have relates to PID control only. After a lot of hard work, I have established which stability derivatives the PID gains depend on so that the job for the user becomes one of estimating certain stability derivatives (for which formulae are also available). The PID gains then drop out as…

Continue

Offer of help with tuning PID loops

Posted on July 19, 2011 at 4:49am 20 Comments

I've noticed quite a lot of debate about tuning PID loops. I think I might be able to help since I've got 40 years experience designing autopilots for air vehicle flight control and navigation. I could give general advice on the best ways of using the P, I and D terms for both primary stability and navigation loops. With more info on the application aircraft I could probably come up with suggestions on which gains to use along with trial values



I think a combination of flight trials… Continue

Comment Wall (4 comments)

At 2:27pm on July 25, 2011, Jonathan Challinger said…
I think nav_bearing might reset with each loop. I'm not certain though, the code is pretty convoluted. I'll do some more looking.
At 8:12am on July 26, 2011, Jonathan Challinger said…
You could look at the ardupilot mega code, if you're interested what APM does. It's pretty messy, though.
At 2:50pm on July 26, 2011, Jonathan Challinger said…
I do actually have an airspeed sensor now. I have a magnetometer, too, so I could theoretically compare the plane's ground vector with the air vector to get a wind speed.
I do have rudder from y-accelerometer, and my ardupilot is mounted at approximately the CG.
I don't have telemetry, so I haven't been able to monitor the accelerometer.
In a real aircraft, the ball is not mounted so precisely near the center of percussion. I don't think it matters that much.

I think there are other issues with the tracking in this code, namely that it gets within the hit radius of the waypoint and then uses the current location to find the track, so my experiments with flying the length of the runway are mostly invalid because it's not using the track from the previous waypoint to the next waypoint, it's using the track from the gps location of the plane when it hit the previous waypoint to the next waypoint.

I want to see this thing fly the centerline. I don't think it's going to happen until I have telemetry for more precise tuning.
At 2:55pm on July 26, 2011, Jonathan Challinger said…

Of course, once I do get it to fly the centerline, an autonomous landing will be a simple matter of having it descend to the ground on the centerline, since it's just a foam plane. A bigger, more fragile plane will need an ultrasonic rangefinder on the bottom of the plane. That would allow for a very precise altitude AGL to be found, which would allow for a precise flare.

You need to be a member of DIY Drones to add comments!

Join DIY Drones

 
 
 

© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service