WKM COG - GPS Measurements to IMU or COG

Multirotorcraft UK

Multirotorcraft UK

Member
Hello everyone. Can I just check on the old topic of COG measurements. Historically I find the COG of the quad and measured to the centre of the IMU and set this distance. Then I have measured from the centre of the GPS unit to the centre of the IMU.

I am now questioning what I am doing regarding the GPS. Do I measure from the GPS to the COG or IMU?. If its to the COG then I have been doing it wrong.

Many thanks.

Andrew
 
Last edited by a moderator:

T

Tahoe Ed

Active Member
Crinson: It is to the COG. X and Y axis are fairly easy to find and place the IMU and GPS. The Z is what hangs people up. Hang your quad by a string from the bottom of a motor in its ready to fly configuration. Follow the line of the string to the intersection of the X and Y axis'. Measure the distance from the string to where you have your IMU mounted that will be your Z for that. And then do the measurement for your GPS.
 





DucktileMedia

DucktileMedia

Drone Enthusiast
I re measured my CG yesterday as I added an additional battery. I have further worries about the WKM in any winds or interference at all now. If i fly the thing in my shop it is dead stable. As soon as i fly out the door it goes crazy! Jumps around in all axis including yaw. I have tried the whole range of gains and I still cant get this thing to fly right. I tried changing the Z # just to see what happened and it makes NO difference. I think that in certain areas it just doesnt want to fly right. I have flown the thing at other locations where it flies pretty well but for some reason at my work it will just not fly smoothly. Very frustrating.
 

Gunter

Gunter

Draganflyer X4
IrisAerial said:
I re measured my CG yesterday as I added an additional battery. I have further worries about the WKM in any winds or interference at all now. If i fly the thing in my shop it is dead stable. As soon as i fly out the door it goes crazy! Jumps around in all axis including yaw. I have tried the whole range of gains and I still cant get this thing to fly right. I tried changing the Z # just to see what happened and it makes NO difference. I think that in certain areas it just doesnt want to fly right. I have flown the thing at other locations where it flies pretty well but for some reason at my work it will just not fly smoothly. Very frustrating.
Click to expand...

Are you using thin electric props? Graupner or similar make a huge difference to stability, both on WKM and Naza.


Regards,

Gunter.
Sent from my iPhone using Tapatalk
 


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