George Tarrant
  • Male
  • Bedfordshire
  • United Kingdom
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George Tarrant's Friends

  • Bruno de Oliveira Motter
  • Turner Hunt
  • SaadTiwana
  • Mike Pursifull
  • Ben Carson
  • Simon
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  • Gabriel Hugh Elkaim
  • kuxz
  • MarcS
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George Tarrant's Discussions

GPS-aided INS

Started Jun 30, 2011 0 Replies

I notice that APM includes triaxial inertial sensors and a GPS unit. Can someone tell me if these units live separately or are they connected together into a loosely-coupled GPS-aided INS? If they…Continue

Fast-track tuning of PID loops

Started Jun 30, 2011 0 Replies

My background is in air vehicle guidance, navigation and control. In the past I've developed autopilot analysis techniques in which an autopilot is "pre-designed" by an expert who expresses autopilot…Continue

 

George Tarrant's Page

Latest Activity

Bruno de Oliveira Motter commented on George Tarrant's blog post New offer of help with tuning PID loops
"Hey george. I'm doing a graduation project involving the system identification of a tricopter. If you could e-mail me what you have already done it would be very useful to me! Here's my e-mail address: hosts2000@yahoo.com.br Thanks!"
Mar 24
George Tarrant left a comment for Turner Hunt
"Hi Turner Good to hear from you. The good news is that I have a lot of autopilot design experience (40 years); what I bring to the table is algorithms for flight control and navigation based on measured or predicted dynamics of the aircraft (I leave…"
Mar 10
MarcS commented on George Tarrant's blog post Fast-track PID lop setup
"George, I think your last question is the most important one in the scope of DIY... The goal of most people will be to just let the plane fly autonomous at all. So some see your offer as a way to make this easier. For this task I´m not sure if…"
Feb 13
George Tarrant commented on George Tarrant's blog post Fast-track PID lop setup
"Hi MarcS You make some good points in your comment; I'll try to deal with them in turn. Firstly, you are correct - the scheme does involve model identification followed by parameter calculation. I too have seen university dissertations where…"
Feb 13
George Tarrant commented on George Tarrant's blog post Fast-track PID lop setup
"Hi Andrew In my blog post I didn't make it clear that my baseline design envisages a flight to capture data followed by processing on the ground. We therefore seem to be thinking along similar lines though you don't say whether you…"
Feb 13

DeveloperJean-Louis Naudin commented on George Tarrant's blog post Fast-track PID lop setup
"Thanks George, a very good foof for thinking... Regards, Jean-Louis "
Feb 13
MarcS commented on George Tarrant's blog post Fast-track PID lop setup
"Hi, from reading the description this is model identification followed parameter calculation for the PID? I know some universities doing or having done research in this field and even when the methods were using more or better sensors (IMU,…"
Feb 12

DeveloperAndrew Tridgell commented on George Tarrant's blog post Fast-track PID lop setup
"Great stuff! Ideally what I'd like to do with ArduPilot is have a program that takes a MAVLink log of a flight and estimates the PID values from the flight data. This wouldn't be in-flight tuning, but would instead be ground based tuning,…"
Feb 12

ModeratorChris Anderson commented on George Tarrant's blog post Fast-track PID lop setup
"Excellent diagram. Many thanks for posting that!"
Feb 12
SaadTiwana commented on George Tarrant's blog post New offer of help with tuning PID loops
"Hi George, I'm very interested in your work. Could you send me more information on my email id below? saadtiwana(at)gmail(dot)com Thanks and best regards,Saad "
Feb 12
SaadTiwana commented on George Tarrant's blog post Fast-track PID lop setup
"Hi George, Very nice post. And very nice idea. May i say that i've been thinking on similar lines too...but haven't implemented anything yet :)  Some question that i have in mind. 1. What do you have in mind to ensure that when the…"
Feb 12
George Tarrant posted a blog post

Fast-track PID lop setup

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 aircraft response to the real…See More
Feb 12
8 Comments
George Tarrant left a comment for Mike Pursifull
"Mike I'm not quite sure what you are saying. Do you thinbk I should have put my most recent offer of PID tuning somehwre else? If so, where?"
Feb 11

DeveloperDoug Weibel commented on George Tarrant's blog post New offer of help with tuning PID loops
"George, what is your approach?  Are you planning on eigensystem postprocessing for system identification or something similar?  I've had that on my long term to do list.     I'm interested to hear how it goes, and if…"
Aug 30, 2011

ModeratorChris Anderson commented on George Tarrant's blog post New offer of help with tuning PID loops
"checking..."
Aug 29, 2011
avionics commented on George Tarrant's blog post New offer of help with tuning PID loops
"Thanks Chris yes that is a well explained PID tuning but i think HEAD_MAX in the Mission Planner PID controller dashboard is called BANK_MAX, correct?"
Aug 29, 2011

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.
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.

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