[stelios]

Hello,

Possibly this is not a LibrePilot issue and it is just me and my hardware, however I'm posting this to learn more from your experience.

Recently, I built my first QuadCopter and I'm now trying to make my first test flight, however the QuadCopter is not taking off at all or more than 1 or 2 cm from the ground. If it goes 1 or 2 cm up, it also flips left or right, not vertical. I think that my battery (7.2V) is not sufficient to power my motors and take-off, however I want your opinion because there might be a chance that I missed something else.

My equipment with total weight of 1.160 kg:

A2212 1000KV + HP 30A ESC + 1045 Prop - https://www.amazon.co.uk/gp/product/B01MA4XW76/
4-axis 450 F Frame - https://www.amazon.co.uk/gp/product/B0178V8D9S/
CC3D - https://www.amazon.co.uk/gp/product/B07W4MND4W/
7.2V 4500mAh NiMH 6 Cell Battery - https://www.amazon.co.uk/gp/product/B074Y1F3QG/

I'm using the latest LibrePilot and I think that I'm following the instructions correctly, I checked the rotation of the motors and the propellers are fitted correctly. I had an issue with the "Transmitter Setup Wizard", I wasn't able to see the sticks moving on the screen but after following https://forum.librepilot.org/index.php?topic=3142.msg21750#msg21750 I solved this as well.

I'm able to arm my QuadCopter and slowly increase the speed of the motors, but even in 100% throttle it won't take off.

Any tips, ideas?

Thank you!

[TheOtherCliff]

I fly those size of motors and props with a 3 cell (12V) LiPo and it works very well.

I think I recall that I flew it once with a 2 cell (8V) LiPo, but it was very underpowered.

I would guess that the difference is that I was using a light lipo battery and you are using a very heavy 4500mAh NiMH.

The best thing would be to use a 3 cell LiPo; say 1000 to 3000mAh.  If you already have bigger props you could try that with your NiMH, but I would not waste money buying larger props.  I would buy a 3 cell LiPo.  If you want to play with it while waiting for parts, you could leave an 8V to 12V battery on the ground and use say a 3 meter cable to give power to the quad. 

You should never steer it before it is in the air.  That causes tip overs.  Takeoff should be just throttle, jump up to knee high.
https://forum.librepilot.org/index.php?topic=4408.0

[stelios]

Great thank you so much for your message and the advises. I thought the same about leaving the battery on ground, I will try it later to see if there is a difference and I will buy a smaller battery with more voltage for future tests. I will update this post.

I forgot to mention the most important thing, I'm using a Raspberry PI zero as my "transmitter". I have connected 4 wires from the PWM pins to the CC3D input plug. It seems that it works ok and the LibrePilot sliders seems to mimic the commands that I'm sending, I have a range of 800 (min) up to 2000 (max) and 1400 as neutral.

The arming process is ok and I can see the throttle going to 800 (0%) and Yaw to 2000 (100%) and then back to 1400.

I can control the throttle, 10% 20% 30%..., what worries me with the PI is that the throttle seems to be 100% from 1700-1750, and then from 1800 to 2000 it doesn't seem to make much difference.

I'm using "pigpio" library.

[TheOtherCliff]

"ESC calibration" reads and stores your PWM min and max into the ESCs, so they know them each time they are powered up.

If you send a PWM signal with larger than max, the ESC just does 100%, the best it can do.

Here are instructions to calibrate all of this so that you get the whole stick range usable:
https://librepilot.atlassian.net/wiki/spaces/LPDOC/pages/12058743/ESC+Calibration

--------------------------------------------

Recall that the CC3D will translate input range into output range, even if the ranges don't match.  It is quite acceptable to have an input range of say 800-1600 and an output range of 1000-2000.  Input of 1600 will translate into output of 2000.

--------------------------------------------

Is there a reason you use 1400 for your PWM neutral?  If you have an RC transmitter/receiver, I would use the same neutrals as it has so I could swap from RPi to RC without changing settings. 

[stelios]

Thank you Cliff, this helps a lot!

I'm following the ESC calibration instructions in the link that you shared but I'm not sure about steps 14 and 15:

14 - Wait just for first beep and immediately press the keyboard Home key.  There are two beep sequences.....
15 - You should hear a set of confirmation 'calibration done' beeps that ESC's are programmed....

In this video you will hear the beeps from my ESCs as I hear them but I'm not sure which one is considered the "first beep" and if I'm getting the "set of confirmation 'calibration done' beeps" in the end. Can you identify them from the video?

Please find attached the output section from the GS after my calibration, I think my settings are not correct because in step (23) I read that the difference should be 2-3 an mine is more than 30 for 1 motor/esc.

23 - The neutral values should all be within 2 or 3 of each other or you may not have a good calibration....

Regarding the input and the output, thanks for the clarification, now it is super clear to me, I didn't know the purpose of input/output tabs before. I'm using 1400 as neutral because I have a graphical slider from (0%) 800 -> 2000 (100%), so in order to make it feel like "balanced" I have it in the middle (1400) (50%) but I can change this.

Lastly, I removed the battery from the frame and tested again, now it is taking off 2-3cm at 1500 but I'm stopping immediately because it is flipping slightly on one side and it is not taking off vertically so I cannot test at full throttle.

Thank you!

[TheOtherCliff]

I'm following the ESC calibration instructions in the link that you shared but I'm not sure about steps 14 and 15:
14 - Wait just for first beep and immediately press the keyboard Home key.  There are two beep sequences.....
15 - You should hear a set of confirmation 'calibration done' beeps that ESC's are programmed....

In this video you will hear the beeps from my ESCs as I hear them but I'm not sure which one is considered the "first beep" and if I'm getting the "set of confirmation 'calibration done' beeps" in the end. Can you identify them from the video?

The beeps in your video are normal startup beeps that you get when the throttle is low at ESC power up.  In that video, did you hear the two beeps of the same tone?  That is telling you that the voltage it reads at startup is about right for a 2 cell LiPo.  The calibration song is slightly different and I guess about 1 to 2 seconds long from what I remember.

Edited Apr 2:
You should follow all the directions (including props off, CC3D powered on via USB and set to full throttle via GCS, and THEN powering up the ESCs) and when the CALIBRATION song is done after a couple seconds, you should press the keyboard key that sets all outputs to Min.  It's not necessary to power up the RPi or "transmitter" at all during this whole procedure.

Please find attached the output section from the GS after my calibration, I think my settings are not correct because in step (23) I read that the difference should be 2-3 an mine is more than 30 for 1 motor/esc.
23 - The neutral values should all be within 2 or 3 of each other or you may not have a good calibration....

That is rather a large amount to be different.  I would recalibrate, but be aware that:
- You should have all your ESC's in parallel powering the FC if they are linear BECs in the ESCs.  Most are...
- Even if you have all ESCs powering the FC, because of manufacturing tolerances, one will have slightly higher voltage than the others.  That ESC will actually be powering the FC and the other 3 ESCs will not provide any real power.  That ESC will be warmer.  Warmer ESCs will need slightly higher numbers to "idle".  I would probably set them all at the higher level, for when they all get warm?

Lastly, I removed the battery from the frame and tested again, now it is taking off 2-3cm at 1500 but I'm stopping immediately because it is flipping slightly on one side and it is not taking off vertically so I cannot test at full throttle.

If it would flip completely over and not just tilt a little, please read at that link in my first post because it has a list of causes for "instant flip (on takeoff)"

You should never steer it before it is in the air.  That causes tip overs.  Takeoff should be just throttle, jump up to knee high.
https://forum.librepilot.org/index.php?topic=4408.0