Replies to This Discussion

3D RoboticsPermalink Reply by Chris Anderson on July 9, 2012 at 8:54pm

What version of the code?

• ▶ Reply

Permalink Reply by Bob Wilkinson on July 9, 2012 at 8:55pm

2.6

• ▶ Reply

Permalink Reply by Bob Wilkinson on July 9, 2012 at 9:20pm

That's on APM2 btw, I didn't make that clear.  More info on my quad is here. 

• ▶ Reply

DeveloperPermalink Reply by jasonshort on July 9, 2012 at 9:41pm

What your seeing is lag in your GPS input being too much for the rate_P value you have. Try lowering loiter rate P.

The reason it's jumping out of a perfect loiter is the GPS hits a threshold and makes the quad think it's traveling faster than it is. it over-corrects with the High gain and you start an oscillation.

Jason

• ▶ Reply

Permalink Reply by Bob Wilkinson on July 10, 2012 at 5:21am

Thanks Jason, I'll give that a try.

Would the new ublox GPS help with the lag?

• ▶ Reply

Permalink Reply by Murray Spoelstra on July 9, 2012 at 10:14pm

I found that with my small quads it works best to reduce Loiter P to 0.2 and Loiter I to 0.05. It also seems to make a difference when I change Nav P to 0.9 and Nav I to 0.05. Finally got Loiter and waypoint flying OK in wind with purple motors, 10x4.7 APC props, 1250g weight and motors on 570mm pitch diameter.

Problem I have though is that when I fly waypoints and choose Loiter turns, it goes into a 45deg bank and drops out of the sky when it starts executing the command. Any suggestions please?

• ▶ Reply

Permalink Reply by Bob Wilkinson on August 23, 2012 at 9:02pm

I had some success with reducing the loiter P, I got it to the point where my loiter would stay within a 5m box or so.

Then I got the ublox GPS, which is worlds better in terms of locking on quickly and getting a higher satellite count / lower hdop.  However when I did some loiter tests I got a very strange result where the quad started an expanding spiral that rapidly got out of control.  Anyone know why this would happen?  I haven't had much time to play with it.

Logs from the incident I'm referring to are attached.

Thanks

Attachments:

• 2012-08-23 23-32 3.log, 840 KB
• 2012-08-23 23-32 3.kmz, 125 KB

• ▶ Reply

Permalink Reply by Markus Järve on December 11, 2012 at 11:38pm

Never underestimate the compass miscalibration possibility. 

• ▶ Reply

Permalink Reply by novrizal herdananto on January 10, 2013 at 4:38pm

hi,

i've just install 2.9 rc2 on my apm2.5. i have just tried loiter in stock pids, and i see quite oscilations.

since i'm a noob, i need advice in which PID i should tune ? attached is my loiter log and param.

Attachments:

• 2013-01-11 06-25 1.log, 352 KB
• my_param.param, 4 KB

• ▶ Reply