confused on gps location & xyz

S

Skinwalk3r

Member
on my f450 i have the mounting bracket squared and centered on the top plate. Is this right ?

my naza is directly under it on the lower plate.


I am a little confused on the re/green xyz.
 

BorisS

BorisS

Drone Enthusiast
Skinwalk3r said:
on my f450 i have the mounting bracket squared and centered on the top plate. Is this right ?
Click to expand...

Thats good. If your quad is in balanced in general ? So the center of the top plate is also the center of gravity on the x and y axis.

Skinwalk3r said:
I am a little confused on the re/green xyz.
Click to expand...

If the GPs unit relative to the COG falls into the green area than you need to input a negative value if its in the red area it needs a positive value. Since you have the gps unit though in the center of your top plate and i assume now that this is also the COG of your quad you can enter 0 for x and 0 for y in the assistant.

Z xis is a different story. The GPS unit will be over the COG on your Z axis thus you need a negative value. Measure the length of the pole and try to find the center of gravity on your Z axis.

Or post a pic and i will try to help you.

Boris
 

S

Skinwalk3r

Member
BorisS said:
Thats good. If your quad is in balanced in general ? So the center of the top plate is also the center of gravity on the x and y axis.



If the GPs unit relative to the COG falls into the green area than you need to input a negative value if its in the red area it needs a positive value. Since you have the gps unit though in the center of your top plate and i assume now that this is also the COG of your quad you can enter 0 for x and 0 for y in the assistant.


Boris
Click to expand...

thank you. here is my confusion ...the diagram in the manual and the assistant seem to convey the idea that the GPS should be installed to the right and back of cog !

even this guy @ 8:10 seems to say that http://www.youtube.com/watch?v=l27d8GDxym8
 

BorisS

BorisS

Drone Enthusiast
no no, the diagram just gives an example how you measure it if your GPS unit id to the right and the back of the COG. If you can place the GPS unit onto the COG the better, you don't have to measure and enter any values.

Boris
 

BorisS

BorisS

Drone Enthusiast
just looked at the video the guy dosent know what he is talking about. I now understand why some people don't get good performance and their position hold :)

Center of aircraft plays no role in all of these measurement. The only thing important is CoG. If you CoG happens to be in the middle of the quad great, ( in general you will have better flight performance ) if the frame allows it mount the IMU/Naza and GPS on the CoG/Center of the Quad.

In the case of the the GPS unit your will not have to enter any values for the x and y axis if on the CoG.


Boris
 

S

Skinwalk3r

Member
aahh ok got it....now to measure z ; if I attach the brackets to top plate and mount the gps on the pole..is the distance measured from the top plate to middle of gps body or is taken from the middle of the NAZA unit (which sits on lower plate) all the way upto middle of gps body
 

BorisS

BorisS

Drone Enthusiast
its taken from the the middle of the GPS unit to the COG on the Z axis. Were the COG is on your axis i can't tell you and its a little tricky to find out. It will probably be somewhere between the two center plates. Looking for a video that explains it for you. One sec
 

BorisS

BorisS

Drone Enthusiast
for sure it will be a negative value since the gps unit is over the COG

check this video its for the WKM but same procedure.

 
Last edited by a moderator:


S

Skinwalk3r

Member
thank you boris. BTW is see that you are in Austria. I hope to be visiting in August. My little sister is getting married in Graz !:)
 

BorisS

BorisS

Drone Enthusiast
Ah very nice Graz and the whole area is very nice. If you come buy vienna drop me line and we can go flying :)

Report from your GPS maiden, if everything worked out.

Boris
 

BorisS

BorisS

Drone Enthusiast
don't forget the calibrate the compass ! otherwise the GPS hold could not be working.

Boris
 


S

Skinwalk3r

Member
Boris. I have a question. I watched the video and tried to relate it to the f450. Where am I going to hold it ? in his video what doesnt make sense is where he holds it. Where he puts his finger would naturally make it top heavy. Shouldn't he find the exact center and then go out from there on Z axis. Example if you have a 30 cm long ruler that you trying to find the cog then you should have the pivot point (finger) at the 15 cm mark. Then by shifting pivot point side to side but always at 15 cm mark one can find cog on that axis. But if you put the pivot point on lets say the 17 cm mark (and 30 mark is low) then it will now be top heavy and will naturally want to lean out and swing down ! cant find cog this way ?
 

BorisS

BorisS

Drone Enthusiast
Were is your lipo mount top plate or under the bottom plate ? If you try to hold your quad vertically with just two finger on the arms in witch direction does it want to turn top plate or bottom plate ? It doesn't have to be 100% If your off 1 or 2 cm its not going to make a big difference.

Boris
 

S

Skinwalk3r

Member
my lipo is under the bottom plate Under one side of the part that is long. On the other side across from lipo is my go pro. Also under bottom plate.
 

BorisS

BorisS

Drone Enthusiast
Okay so you quad will be bottom heavy the motors alone on top won't balance it out that the COG is directly in the middle between bottom and top plate. Consider your bottom plate to be the COG for now and measure from the bottom plate to the middle of the unit. Take that value and enter is as a negative. Try it out like this and if the position is not held perfectly in GPS mode than add a couple cm to increase the negative number.

The copter will not crash or anything if the Z value for the GPS unit is not spot on. You will just notice the the GPS hold is not as good or you get the toilet bowl effect.

Boris
 


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