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Forward tilt at startup

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Hi I just received a hexaxXL which I'm having trouble getting off the ground. This is not my first Multirotor so I have a little experience.

The problem is that the Hexa wants rotate forward and ends up on it's head if i try to take off. I tripple checked motor direction, props rotation, motor layout etc, re-flashed all firmware, re-calibrated but but still the same issue. I'm thinking maybe a weak motor? but all seem to be fine.
Below is a link to a screenshot of the scope while i try to startup, for some reason only 4 motors are selectable. But it's a hexa. As you can see the flight controller is trying to adjust the rear motors to counteract the nick forward but it's not working responding.

https://1drv.ms/i/s!AtWZQxEqLM0Hg6FHPvFaPQ0hGLtU9w
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I've noticed if I apply transmitter trim on nick I can even things out but I cant fly outdoors at the moment. It behaves like it's in heading/hold mode and behaves the same when I place it in that mode.

Another scope output of an tilt on takeoff.

https://1drv.ms/i/s!AtWZQxEqLM0Hg6FI6Monh21DCW7NwA

Thanks guys any advice greatly appreciated
« Bearbeitet von wildtypitch am 27.05.2017 13:52. »
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Calibrate the acc!!
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solutionxxl meinte
Calibrate the acc!!

Yes i calibrate the acc it returns the acc values to zero but makes no difference (I understand that the acc values in the scope are not a measure of acceleration but angle so small deviation should be normal). As i say trim helps but i shouldn't have to apply that much no?
Might this be a problem, the centre plate is slightly warped meaning the front arm is about a centimetre lower at the motor end than the rear arm motor?
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hmm if i tilt the flight controller with shims towards the direction of the forward movement it looses it's forward tilt. But if I re-calibrate the ACC at this point it goes back to the forward tilt. it's like the ACC calibration is consistently off. I'm thinking out loud sorry if I'm going round in circles. an d not seeing the obvious.
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The problem is that the Hexa wants rotate forward and ends up on it's head if i try to take off. I tripple checked motor direction, props rotation, motor layout etc, re-flashed all firmware, re-calibrated but but still the same issue. I'm thinking maybe a weak motor? but all seem to be fine.

... for some reason only 4 motors are selectable. But it's a hexa. As you can see the flight controller is trying to adjust the rear motors to counteract the nick forward but it's not working responding.

In Koptertool Motor test can you start each 6 motors individually?

Does one of the arms vibrate more than other arms when you run motor test? On your smart phone use "Hamm Seismograph" app, balance the smart phone on the arm then run motor.

Have your selected the correct hexa-copter layout?
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wildtypitch meinte
hmm if i tilt the flight controller with shims towards the direction of the forward movement it looses it's forward tilt. But if I re-calibrate the ACC at this point it goes back to the forward tilt. it's like the ACC calibration is consistently off. I'm thinking out loud sorry if I'm going round in circles. an d not seeing the obvious.

Do you use a proper spirit-level (DE: Wasserwaage) to measure horizontal when you perform ACC calibrate?
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wildtypitch meinte
hmm if i tilt the flight controller with shims towards the direction of the forward movement it looses it's forward tilt. But if I re-calibrate the ACC at this point it goes back to the forward tilt. it's like the ACC calibration is consistently off. I'm thinking out loud sorry if I'm going round in circles. an d not seeing the obvious.

Do you use a proper spirit-level (DE: Wasserwaage) to measure horizontal when you perform ACC calibrate?

Yes I used a spirit level. Even if it was a little off it wouldn't explain the full 90 degree tilt without adjustment
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wildtypitch meinte
hmm if i tilt the flight controller with shims towards the direction of the forward movement it looses it's forward tilt. But if I re-calibrate the ACC at this point it goes back to the forward tilt. it's like the ACC calibration is consistently off. I'm thinking out loud sorry if I'm going round in circles. an d not seeing the obvious.

Do you use a proper spirit-level (DE: Wasserwaage) to measure horizontal when you perform ACC calibrate?
Thanks for the replies, 5 of the arms have landing legs and the front one does not, so I presume it would have more vibration on the ground. but it doesn't look so bad, I've not tested with a vibration meter. But this copter has had this setup for years now and was fine before i received it.
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wildtypitch meinte
Yes I used a spirit level. Even if it was a little off it wouldn't explain the full 90 degree tilt without adjustment

Ok, another test you can do:

With Koptertool 3D screen and hexa-copter connected (data radio or serial cable), does the copter behave same on the screen as when you move the hexa-copter around and turn it?
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the 3d screen is perfect
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wildtypitch meinte
the 3d screen is perfect

Ok, another point to check is motor angle adapters.
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wildtypitch meinte
the 3d screen is perfect

Ok, another point to check is motor angle adapters.


There are no angle adaptors on this copter.
The flight controller is FC 2.2 which I can't find anything about. Could it be that the latest firmware update I installed isn't suitable for this FC?
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wildtypitch meinte
There are no angle adaptors on this copter.
The flight controller is FC 2.2 which I can't find anything about. Could it be that the latest firmware update I installed isn't suitable for this FC?

Ok, no angle adapters, that should also work if none are installed.

Do you have the standard alu frame?

Do you have a photo of the hexa-copter?

FlightCtrl 2.2 is a FlightCtrl 2.1 with an upgraded ACC chip. They are very common, because it was a very good upgrade for making precise vertical movement and cm precision landings. I have one, that I have used 4 years. However if the upgraded chip is not correctly installed that could be a problem. Do you have a close-up photo of the flight-controller?

Software 2.18 is compatible with FlightCtrl 2.2. However I have not yet tested it myself, that copter still has software 2.16.
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There are no angle adaptors on this copter.
The flight controller is FC 2.2 which I can't find anything about. Could it be that the latest firmware update I installed isn't suitable for this FC?

Ok, no angle adapters, that should also work if none are installed.

Do you have the standard alu frame?

Do you have a photo of the hexa-copter?

FlightCtrl 2.2 is a FlightCtrl 2.1 with an upgraded ACC chip. They are very common, because it was a very good upgrade for making precise vertical movement and cm precision landings. I have one, that I have used 4 years. However if the upgraded chip is not correctly installed that could be a problem. Do you have a close-up photo of the flight-controller?

Software 2.18 is compatible with FlightCtrl 2.2. However I have not yet tested it myself, that copter still has software 2.16.


Yes the copter was working with this setup previously. Here's a onedrive link to pictures and a video of attempted take off. Video of the telemetry screen, notice how the conjured bearing at the top of the screen is twitching. Not sure if this had anything to do with this issue though.
https://1drv.ms/f/s!AtWZQxEqLM0Hg6FM5t9NEHQzLV9TpQ
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wildtypitch meinte
Yes the copter was working with this setup previously. Here's a onedrive link to pictures and a video of attempted take off. Video of the telemetry screen, notice how the conjured bearing at the top of the screen is twitching. Not sure if this had anything to do with this issue though.
https://1drv.ms/f/s!AtWZQxEqLM0Hg6FM5t9NEHQzLV9TpQ

I cannot see everything but the ACC chip install looks Ok.

compass bearing twitching: Have you calibrated the compass?

How did you determine north direction for calibration? It is most easy to use a classic needle compass. If you use a compass app in a smart-phone that one also has to be calibrated before use.

Do you use internal compass on the NaviCtrl (default) or external compass?

Do you have a log file from the NaviCtrl MicroSD card of your nearly flights? You can view the files with GPX Tool.
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wildtypitch meinte
Yes the copter was working with this setup previously. Here's a onedrive link to pictures and a video of attempted take off. Video of the telemetry screen, notice how the conjured bearing at the top of the screen is twitching. Not sure if this had anything to do with this issue though.
https://1drv.ms/f/s!AtWZQxEqLM0Hg6FM5t9NEHQzLV9TpQ

I cannot see everything but the ACC chip install looks Ok.

compass bearing twitching: Have you calibrated the compass?

How did you determine north direction for calibration? It is most easy to use a classic needle compass. If you use a compass app in a smart-phone that one also has to be calibrated before use.

Do you use internal compass on the NaviCtrl (default) or external compass?

Do you have a log file from the NaviCtrl MicroSD card of your nearly flights? You can view the files with GPX Tool.


Yes calibrated the compass many times.

determined north by the roads, I'm currently in Beijing. north south axis for most the roads :)

There is no external compass on this build only the internal one.

with just the flight controller (removed the navi and gps) I still saw the same results tryin g to take off.

I've uploaded the logs from recent attempts if you think that helps. Same link as before

https://1drv.ms/f/s!AtWZQxEqLM0Hg6FM5t9NEHQzLV9TpQ
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wildtypitch meinte
determined north by the roads, I'm currently in Beijing. north south axis for most the roads :)

Lots of GPX log files, I only checked one file 17052618.GPX. There the roads are NOT north-south, but at an angle.

In the GPX log I see that indeed the current for motor 1 is very low (in MKGPXTool overview and in GridView column MotorCurrent. Is this the same for all flight attempts? Would it be the same if you turned the direction of the hex-copter 180 degree?


Thank you for showing the photos, it can sometimes help.

Does your hexa-copter have detachable arms?

That is special. It is of course possible but it is another possible source of errors.

Weak motor 1: The plugs between motor controller and motor are they somehow dirty or oxidized (rusted), try disconnect, then reconnect the motor plugs.
« Bearbeitet von Foersom am 30.05.2017 10:37. »
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wildtypitch meinte
determined north by the roads, I'm currently in Beijing. north south axis for most the roads :)

Lots of GPX log files, I only checked one file 17052618.GPX. There the roads are NOT north-south, but at an angle.

In the GPX log I see that indeed the current for motor 1 is very low (in overview and in GridView column MotorCurrent. Is this the same for all flight attempts? Would it be the same if you turned the direction 180 degree?


Thank you for showing the photos, it can sometimes help.

Does your hexa-copter have detachable arms?

That is special. It is of course possible but it is another possible source of errors.

Weak motor 1: The plugs between motor controller and motor are they somehow dirty or oxidized (rusted), try disconnect, then reconnect the motor plugs.


Yes I'm sure my north was correct, I've taken a look at the motor connections, nothing unusual or oxidised. The current on motor 1 yes is lower hence the tilt. I'd assume that that means it's more likely that it's not a esc/motor fault but that it's been given less current from the fc. Yes i believe the arms have been made detachable but it's a very secure and stable connection. Thanks for taking a look
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The current on motor 1 yes is lower hence the tilt. I'd assume that that means it's more likely that it's not a esc/motor fault but that it's been given less current from the fc.

Something to try: Take off all propellers. Put the hexa-copter on a table (i.e. perfectly horizontal). Start the motors from RC transmitter and let them run at idle. Does the motor 1 run slower than other motors?

Lift the hexa-copter by hand and twist it forward (nick direction) so arm 1 is moved downwards. Does motor 1 spin faster to try to regain the copter balance?

With motor test (and no propellers), one at a time set each motor to full throttle. Can all motors run at same speed?
« Bearbeitet von Foersom am 31.05.2017 09:39. »
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The current on motor 1 yes is lower hence the tilt. I'd assume that that means it's more likely that it's not a esc/motor fault but that it's been given less current from the fc.

Something to try: Take off all propellers. Put the hexa-copter on a table (i.e. perfectly horizontal). Start the motors from RC transmitter and let them run at idle. Does the motor 1 run slower than other motors?

Lift the hexa-copter by hand and twist it forward (nick direction) so arm 1 is moved downwards. Does motor 1 spin faster to try to regain the copter balance?

With motor test (and no propellers), one at a time set each motor to full throttle. Can all motors run at same speed?


Well I can't tell you with ears alone whether motors are spinning at the same speeds but yes they all react accordingly with opposite tilt and all roughly about the same.

Is there any more data I can scope?

Why with my hexa do I only get 4 selectable motors in the scope

can I see what the fc is outputting to the motors?
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some ideas what you may check, if not done already:

- are you sure to use the correct mixer table?
- the FC arrow points to motor 1 (no angle offset), right?
- do the rc sticks correspond with the channel display in the mk tool?
- heading hold de-activated?
- use setting 3 with all defaults?

Armin
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basics all covered there i think.
But one thing I'm not so clear on its the different settings and how you can alter them in settings. I understand the different stick positions to change the default, but not the defaults themselves
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wildtypitch meinte
... but not the defaults themselves


in MK Tool 2.16 there is a button with an exclamation mark named "reset". Older versions of MK tool use always defaults by the first run.

Armin
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wildtypitch meinte
... but not the defaults themselves


in MK Tool 2.16 there is a button with an exclamation mark named "reset". Older versions of MK tool use always defaults by the first run.

Armin

Some new studies. See the slow response in the video below from the nick/pitch accelerometers, It would surely explain why the kopter flips over the nick axis. It's very hard to get an accepted calibration on the compass.
https://youtu.be/MouQCqvBhkE
Faulty Accelerometer from the FC2.2 upgrade?

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MikroKopter - Forum » Newbie - Bereich » Forward tilt at startup