XAircraft Placement of wokong IMU, and the XYZ measurements

Highalander

Highalander

Member
I have just completed the build of my X650 V4 value, and am installing the wookong M. Is there any reason not to put the IMU in the centre of the bottom plate of the quad and the MC on the stilts above it. Also I am confused as to what the XYZ measurement should be. The IMU is right on the C of G, so I presume the values are all 0. The GPS unit is 13cm dead centre in front of the IMU with the dome 7 cm above the IMU centre, so Im thinking X = 13cm, is this right? I have ventured into unknown territory here so all your help would be appreciated.
 
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BorisS

BorisS

Drone Enthusiast
If the IMU is sitting on the COG then X and Y will be zero. You still have to consider the Z axis though. In most cases the IMU will not be on the COG on the z axis.
If the GPS is in front of the IMU and the IMU is on the COG for the Y and X axis than enter the 13 as a positive for the X axis in the config tool and Y = 0 because GPS stays on COG for that axis.

Z again for GPS is the question were your COG for the Z axis is. You have to find that or approx guess were it is.

Boris
 

Highalander

Highalander

Member
Well had a short flight late afternoon and X650 behaved very well in both attitude and gps. Only flew for about six mins though as there were some spots of rain beginning to fall. Thanks Boris for the reply, what or where is the Z axis. I can only guess that its when the quad is tilted to vertical where the CoG is slightly below IMU (on the load carriers) or am I barking up the wrong tree?
 

BorisS

BorisS

Drone Enthusiast
I think this video is going to help you. But you are on the right track anyways

Boris

 
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krleas

krleas

FPV Freak
So if u have heavier cam, center of gravity moves and u must setup everytime when u switch camera?
 


Highalander

Highalander

Member
Well had three flights today up our flying field. Got to say I was very impressed with the performance of the X650 V4. Windy conditions and it held fast all be it a little tilted into wind. All I have to do now is pluck up the courage to switch off the TX and see if Go Home works. Seems very strange deliberately turning off a TX, but I need to know so that I can plan ahead for FPV flight. I still think it needs a little tweaking on gains, but will do this when its not so windy.
 

BorisS

BorisS

Drone Enthusiast
Two ways to go sure to test Failsafe. Put it on you radio instead of manual flight mode for example. So you can test it without switching off your radio.

Or setup you bird ready to start but props off. Start the motors but keep it on low rpm. Switch off the radio and look if the motors spin up. Switch back on the radio and bring down the motors again. Don't let them spin to long without props.

But with these two steps done before you should be on the safe side !

Boris
 


Highalander

Highalander

Member
Tried the failsafe today as Boris suggested and all went ok, well almost - I upgraded to latest firmware and two of my motors wouldn't spool up same time as the other two. Turns out the motors need to be set at one click from high on the new addition to firmware. Will be looking at camera and gimble very soon :)
 

Highalander

Highalander

Member
Now done the failsafe with Tx switched off and all went well, have the camera gimble fitted and set up. I got to say I have had no problems with set up except when I connected one of the Escs the wrong way round, took me 10mins to find that boob boo! :shame:.
 



M

Mihnea de Vries

Member
I was asking if anyone knows from where start measure distance from IMU to COG, from the top side of the IMU or from the Bottom side, because there is no clue on manual abut this. Since IMU is about 3 cm tall box, so there will be a 3cm error if is measured from the wrong side. The same question apply to all 3 axes.

I assumed to measure from diagonal intersection of the IMU box and i probably assumed right because my octo is very stable, but i still want to know exactly where to start.
 

Highalander

Highalander

Member
Mihnea de Vries said:
I was asking if anyone knows from where start measure distance from IMU to COG, from the top side of the IMU or from the Bottom side, because there is no clue on manual abut this. Since IMU is about 3 cm tall box, so there will be a 3cm error if is measured from the wrong side. The same question apply to all 3 axes.

I assumed to measure from diagonal intersection of the IMU box and i probably assumed right because my octo is very stable, but i still want to know exactly where to start.
Click to expand...

Yes from the centre of imu in horizontal and vertical.
 

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