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MavLink Failed: Getting Param... (sysid1 compid1) and then nothing...

Started by Oliver Volkmann. Last reply by Oliver Volkmann 5 hours ago. 10 Replies

This is weird. I am seeing my altitude, ground speed, yaw and vertical speed as well as my position in the Flight Data screen almost immediately after I click on "Connect" in Mission Planner however…Continue

Y6 not lifting off

Started by Ben Snyder. Last reply by Randy 16 hours ago. 19 Replies

I'm trying to get my RTF Y6 off the ground for the first time. I calibrated the ESCs, checked motor spin, ran the calibration wizard in MP (Turns out I had to run a virtual machine on my Mac to use…Continue

APM Failsafe

Started by Damo. Last reply by Reuben 23 hours ago. 7 Replies

From my work in attempting to figure out Failsafe i see that the APM ALWAYS treats the throttle channel as the failsafe channel i.e RCMAP_THROTTLE in the full parameter list. Can i change what…Continue

Why NAZA work without PIDS tuning and APM not?

Started by Thomas. Last reply by Esteban Jaramillo 23 hours ago. 48 Replies

Hi, All my friends that flying NAZA asking me why i did not buy DJI NAZA as it work from the box.... I build my F450  based on APM 2.6 and still tuning it... Well it still fly like a boat on the…Continue

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Comment by avionics on December 9, 2012 at 9:45am

2012-12-09%2020-01-10.tlog

 

Hi Guys

I was in the middle of tuning for my Loiter and suddenly the quad started coming down out of control and crashed. Luckily no damage but it went out of control. this is the log i appreciate if any one can help and see what went wrong. thanks

 

2012-12-09%2020-01-10.tlog

 

Comment by avionics on December 7, 2012 at 8:16am

OK I got the Loiter going almost good. I had problem with my CH_6 knob on TX. fed the info directly from the ground station. all good for now. Thanks.

 

Comment by avionics on December 6, 2012 at 10:26pm

@Randy

Randy thank you for the response. Frankly I dont really know what to look for in the log. any idea what i should expect in the log? sorry I have never done this before.

Comment by Randy Brazeau on December 6, 2012 at 11:38am

@Avionics

Have you reviewed the logs? That would be a good starting point to see what is happening.

Randy

Comment by avionics on December 6, 2012 at 11:04am
I have a H.A.L quad by hobby king with 1200kv motors and freshly assembled. It flies beautiful in stablise and alt Hold and when i try to loiter it doesnt hold its position. The GPS both LEDs are locked and steady before i start. It drifts and loses altitute very slowly. Tried playing with PIDs but no luck. I ran out of ideas appreciate if anyone can throw some light. Does the WP loiter config PIDs have any effect whilst on loiter or it is only for when on Auto mode? Thanks for the help in advance.
Comment by Chris Gough on November 29, 2012 at 1:36am

@Shayam, if you want to experiment with quaternions, DCM, euler angles, etc. you might want to check out the various pluggable AHRS subsystems in paparazzi.

http://paparazzi.enac.fr/wiki/Subsystem/ahrs

Comment by Shyam Balasubramanian on November 29, 2012 at 1:24am

@Randy, Thanks for that nice explanation on accelerometer with quads! Now, my understanding gets better.

I would want to try out Quaternions once myself, it seems different people are having different opinion. My friend, who works purely on Quad uses quaternion. He mentioned to be that it was 'much' faster than DCM. But, since truth is one but scenarios differ, I will ask him if he can lend me some benchmarking ;)


Developer
Comment by Randy on November 29, 2012 at 1:15am

@Shyam re Quaternions,

     There's a thread by Bill Premerlani re DCM vs Quaternions.  My understanding is that they're equivalent.  II think perhaps DCM is faster but maybe not, i'm not sure.  I don't think it's as simple as one has 4 elements so it's faster than the other that has 9.

     When the copter/plane accelerates in any direction, the accelerometers sees this.  The problem is that we generally use the accelerometers to tell us which way is down.  So any acceleration of the copter/plane has the potential to throw off our attitude estimate.  Normally the accelerations are short-lived so they don't cause much problem but if they're long lived (for example you're constantly travelling in a circle) it can be a real problem.

-Randy

Comment by Shyam Balasubramanian on November 28, 2012 at 3:51pm

@Randy,

Thank you for your thoughts on implementing quaternions. I have a question, quaternions are supposed to be faster as they use 4 elements unlike DCM which uses 9, and does not suffer gimbal locks (even DCM does not, but one should know how to avoid it there though), it must result in faster computation right?

And what does "the centrifugal (centripetal) force which can throw off the accelerometers" means?

Thanks!


Developer
Comment by Randy on November 26, 2012 at 1:41am

@Shyam re "using quaternions in APM"
     We pulled out the Quaternion attitude estimation from ArduCopter after 2.6.  It didn't perform better than DCM so it was just slowing down the developers who had to maintain two parallel ahrs classes.  You can find 2.6 in the downloads area but can't make any promises about being able to support it or what incompatibilities with the mission planner may have appeared.

    If you want to try it you should add this to your APM_Config.h:

#define QUATERNION_ENABLE ENABLED

 

Now if you're talking about using the attitude estimation from the MPU6000's DMP unit (which spits out it's results in Quaternions), you can simply add this to your APM_Config.h:

# define DMP_ENABLED ENABLED

A few people on the dev team have flown it (including me) and from the limited testing we did, it's results were nearly identical to the DCM but it doesn't offer us some features that DCM does like centrifugal (centripetal?) force which can throw off the accelerometers.

 

 
 
 

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