HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 13, 2015, 02:33 PM
Registered User
Joined Feb 2015
87 Posts
Discussion
APM Quadcopter Drifting Fwd

Hi! My APM quadcopter is constantly drifting forward when flying both in Stabilized and Alt Hold modes (have not tried Loiter since my GPS/Compass is not working properly).

I don’t think it is a calibration issue, since I’ve calibrated the sensors several times, and when the vehicle is lying completely flat on the ground, the attitude indicator on the Mission Planner shows 0 pitch and 0 roll

I don’t think it’s a CG issue, ‘cause the CG position is quite in the middle of the frame (just a little bit to the rear).

I have calibrated manually all the ESC’s several times, but sometimes the left front motor seems to start spinning a little bit later than the others when I increase the throttle slowly, so maybe that could be the cause.

What do you reckon? If the cause is the slower turning motor, how could that be fixed?
girarcat is offline Find More Posts by girarcat
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 13, 2015, 02:37 PM
Registered User
United States, OR, Grants Pass
Joined Apr 2014
239 Posts
Quote:
Originally Posted by girarcat View Post
Hi! My APM quadcopter is constantly drifting forward when flying both in Stabilized and Alt Hold modes (have not tried Loiter since my GPS/Compass is not working properly).

I donít think it is a calibration issue, since Iíve calibrated the sensors several times, and when the vehicle is lying completely flat on the ground, the attitude indicator on the Mission Planner shows 0 pitch and 0 roll

I donít think itís a CG issue, Ďcause the CG position is quite in the middle of the frame (just a little bit to the rear).

I have calibrated manually all the ESCís several times, but sometimes the left front motor seems to start spinning a little bit later than the others when I increase the throttle slowly, so maybe that could be the cause.

What do you reckon? If the cause is the slower turning motor, how could that be fixed?
Have you actually trimmed it out? I see you have checked a few things but have you done the auto trim and auto tune procedures? The auto trim should take care of any drifting around.
flyslikearock is online now Find More Posts by flyslikearock
Reply With Quote
Old Mar 13, 2015, 04:38 PM
Registered User
Joined Feb 2015
87 Posts
No, I haven't. I didn't know such thing existed. I'm pretty sure this will solve my problem. I'll give it a shot and I'll let you know the results.
Thanks!
girarcat is offline Find More Posts by girarcat
Reply With Quote
Old Mar 13, 2015, 07:24 PM
reelflyt
Edmonton, Alberta, Canada
Joined Mar 2010
867 Posts
Hi .

Go on Youtube and look up Painless 360 videos I told you about before and review how to auto trim . It is easy . Once you have it trimmed it should improve . But never use the trims on your transmitter . Always trim the board .

Gordon
reelflyt is offline Find More Posts by reelflyt
Reply With Quote
Old Mar 15, 2015, 04:07 PM
Registered User
Joined Feb 2015
87 Posts
Quote:
Originally Posted by reelflyt View Post
Hi .

Go on Youtube and look up Painless 360 videos I told you about before and review how to auto trim . It is easy . Once you have it trimmed it should improve . But never use the trims on your transmitter . Always trim the board .

Gordon
Thanks! Just done it. The forward drift has disappeared... but now I have a right side drift. I have repeated the procedure several times. Every time I get a different drift direction (sometimes fwd, sometimes to the right, another backwards…)

Furthermore, during the first 10 seconds of the auto trim flight, the quadcopter becomes completely unstable, making it almost impossible to control (I've been about to crash it against my house). After the first 10s, it starts to behave as normal, and I can make it hover steadily (applying some corrections though). Is it normal?

Thanks!
girarcat is offline Find More Posts by girarcat
Reply With Quote
Old Mar 15, 2015, 05:10 PM
reelflyt
Edmonton, Alberta, Canada
Joined Mar 2010
867 Posts
Hi.

When you fly a quad you still have to put inputs to keep it from drifting occasionally. Do not think that all you have to do is say go here or go there . You still have to fly it . The slightest breeze or puff of wind will make it drift .

Gordon
reelflyt is offline Find More Posts by reelflyt
Reply With Quote
Old Mar 15, 2015, 05:50 PM
Registered User
Joined Feb 2015
87 Posts
Yeah, maybe you’re right and that's all the stability I can get from it, but I'll try to record a video to show you how it flies, because I think it's drifting too fast to be considered as normal. If I release the sticks, it stays steady for a couple of seconds and then it starts a relatively high speed drift. Maybe a slow drift to one side is normal, but in my case I am not sure it can be considered as normal…

Thanks!
girarcat is offline Find More Posts by girarcat
Reply With Quote
Old Mar 16, 2015, 09:45 AM
Registered User
United States, VA, Newport News
Joined Dec 2014
60 Posts
How much vibration are you getting. A high vibration might be throwing the controller off as it sits in a hover making it start to drift.
Toastdude82 is offline Find More Posts by Toastdude82
Reply With Quote
Old Mar 17, 2015, 02:18 PM
Registered User
Joined Feb 2015
87 Posts
How am I to measure the vibration? If I download the flight logs the vibration graph is always blank..
By the way, the APM board is mounted on shock absorber platform.
girarcat is offline Find More Posts by girarcat
Last edited by girarcat; Mar 17, 2015 at 04:07 PM.
Reply With Quote
Old Mar 17, 2015, 02:22 PM
Registered User
Canada, AB, Calgary
Joined Aug 2014
18 Posts
Quote:
Originally Posted by girarcat View Post
How am I to measure the vibration? If I download the flight logs the vibration graph is always blank..
I believe you have to enable recording of vibration levels. Sorry, I'm still quite new too and don't recall where it is but a google search should help. Pretty sure it's under standard parameters (pixhawk).

Someone here will know where it is too.
Great Crouton is offline Find More Posts by Great Crouton
Reply With Quote
Old Mar 17, 2015, 04:09 PM
Registered User
Joined Feb 2015
87 Posts
Okay, here you are an explanation:
http://copter.ardupilot.com/wiki/ac_measuringvibration/

I'll try that next time. I'm sure my results are gonna be awful, 'cause I can hear the frame vibrating every time I fly...

thanks
girarcat is offline Find More Posts by girarcat
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Glitchy APM Drift Mode selbold Multirotor Talk 0 Nov 25, 2014 06:03 PM
Build Log Upgrading My F450 Quadcopter from kk2.0 to ArduFlyer/APM 2.5 Shane QG Multirotor Talk 6 Aug 23, 2014 07:19 PM
Build Log Upgrading My F450 Quadcopter from kk2.0 to ArduFlyer/APM 2.5 Shane QG Multirotor Talk 0 Sep 08, 2013 04:58 PM
Question What are some good Quadcopter frames for APM? Beeler19 Multirotor Talk 0 Feb 27, 2013 07:00 AM