startrek66

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RTB mode
« on: September 18, 2018, 08:25:51 am »
hi guys, currently flying with stabilized 1 and velocity roam. I would like to add RTB. I checked the page at the following link https://librepilot.atlassian.net/wiki/x/OwC4 and I set the parameters.
 I ask you if it is correct to set for the RTB mode the stabilization configuration equal to that of VELOCITY ROAM.
Regards

Re: RTB mode
« Reply #1 on: September 18, 2018, 09:24:23 am »
For this question, Velocity Roam is equivalent to Position Hold, so yes, RTB should work fine if VR is working fine.

Understand where "base" is.  By default it should be where you armed.  Make sure this works, I recall some issues where it actually seemed to be where the GPS first got a good lock.

In System -> Settings -> FligthModeSettings there is a settings called ReturnToBaseNextCommand.  Default value is Hold (PositionHold).  Consider whether you want to set it to Land (automatic landing after reaching base).

ReturnToBaseAltitudeOffset might need to be increased if you fly at ground level behind tall trees and want it to climb higher than the default of 10m before returning to base, but that is dangerous if it would typically hit the tree when climbing.

Understand that there are two forms of failsafe; RC, and FC.  They both work.  Consider setting a failsafe to do RTB.  Beware that you need to be careful to switch things off in the correct order once you set this up.  If the quad is armed, and you switch the transmitter off, it may jump up and do RTB.
« Last Edit: September 18, 2018, 09:47:31 am by TheOtherCliff »

startrek66

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Re: RTB mode
« Reply #2 on: September 18, 2018, 07:51:52 pm »
Thanks for the information. I will use your advice to make a correct parameter setup. my quadcopter in VR mode flies well and holds the position when the gas is at 50%. here the video of one of my tests in position hold.

(use youtube.com link because youtu.be link does not work in the forum)


I definitely have to choose a type of fail safe. I would like to start with a return to the base without however autonomous landing. therefore the correct procedure should be as follows: takeoff with stabilized, removal and change in VR. then inserting the RTB mode. the quadrocopter should move above the vertical from which it takeoff, stopping at a height of 10 m higher than the one in which I entered the RTB mode. so I should switch to VR mode and take it to the landing.
« Last Edit: September 18, 2018, 07:59:59 pm by TheOtherCliff »

startrek66

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Re: RTB mode
« Reply #3 on: September 23, 2018, 12:55:09 am »
hi guys, currently flying with stabilized 1 and velocity roam. I would like to add RTB. I checked the page at the following link https://librepilot.atlassian.net/wiki/x/OwC4 and I set the parameters.
 I ask you if it is correct to set for the RTB mode the stabilization configuration equal to that of VELOCITY ROAM.
Regards
I ask you if I have correctly adjusted the setting of the thrust for the rtb mode (see photo)

Re: RTB mode
« Reply #4 on: September 23, 2018, 08:19:09 am »
I forget whether (default settings) RTB stops the motors when you move the throttle to zero.  I think it stops the motors.  Your FC failsafe is set to move the throttle to zero.  It's easy to test.  :)

I don't have "-100" throttle on any of my RTB failsafe setups.

startrek66

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Re: RTB mode
« Reply #5 on: September 23, 2018, 08:33:15 am »
I forget whether (default settings) RTB stops the motors when you move the throttle to zero.  I think it stops the motors.  Your FC failsafe is set to move the throttle to zero.  It's easy to test.  :)

I don't have "-100" throttle on any of my RTB failsafe setups.
I found this fail safe motor setting as default in the gcs. I have only assigned that in case of fail safe intervention the RTB is activated. but how can I test without flying?

Re: RTB mode
« Reply #6 on: September 23, 2018, 03:52:25 pm »
I assume you are using FC failsafe (not RC failsafe).

Well you could take the props off, FMS to ATtitude (or Rate) mode, arm, carry quad away from Base location, increase throttle to 50% (motors should spin), switch transmitter off.  That would test that failsafe does what you think it does.  If you are using FC failsafe with the settings you posted, the motors should stop.

Also: take the props off, FMS to ATtitude (or Rate) mode, arm, carry quad away from Base location, increase throttle to 50% (motors should spin), switch FMS into RTB (motors change, but still running), reduce throttle to zero; motors should stop.  Increase throttle to 50%; motors should come back on.  That would test how RTB works with live transmitter sticks, not RTB with configured FMS stick positions.

Of course if you are using RC failsafe with throttle set to zero, there is no difference between these two.

I don't like taking my props off, so for a quad (different for airplane) I would:
 - fly at least 15m high and 50m away from Base,
 - be ready on FMS to switch to some mode you know works
 - throttle stick at hover power, switch FMS into RTB
 - if that is OK, it should climb 10m and start flying toward Base
 - for 1 or 2 seconds, play with throttle from 25% to 100%; changing the throttle like this should not actually do anything.
 - drop throttle from mid stick to zero and immediately move throttle back to mid stick
 - you should see motors stop and immediately restart, just like ALtitudeHold / ALtitudeVario thrust modes

startrek66

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Re: RTB mode
« Reply #7 on: September 30, 2018, 05:49:07 pm »
I assume you are using FC failsafe (not RC failsafe).

Well you could take the props off, FMS to ATtitude (or Rate) mode, arm, carry quad away from Base location, increase throttle to 50% (motors should spin), switch transmitter off.  That would test that failsafe does what you think it does.  If you are using FC failsafe with the settings you posted, the motors should stop.


It works exactly like this

Also: take the props off, FMS to ATtitude (or Rate) mode, arm, carry quad away from Base location, increase throttle to 50% (motors should spin), switch FMS into RTB (motors change, but still running), reduce throttle to zero; motors should stop.  Increase throttle to 50%; motors should come back on.  That would test how RTB works with live transmitter sticks, not RTB with configured FMS stick positions.

Unfortunately I did not perform exactly your procedure. After changing RTB mode I turned off the transmitter and the engines didn't stop.
I'll do the test again, even if I think it's right that the engines don't have to stop.


Of course if you are using RC failsafe with throttle set to zero, there is no difference between these two.

I don't like taking my props off, so for a quad (different for airplane) I would:
 - fly at least 15m high and 50m away from Base,
 - be ready on FMS to switch to some mode you know works
 - throttle stick at hover power, switch FMS into RTB
 - if that is OK, it should climb 10m and start flying toward Base
 - for 1 or 2 seconds, play with throttle from 25% to 100%; changing the throttle like this should not actually do anything.
 - drop throttle from mid stick to zero and immediately move throttle back to mid stick
 - you should see motors stop and immediately restart, just like ALtitudeHold / ALtitudeVario thrust modes


I also have a new question about RTB. I didn't set the auto landing. I noticed that when the quadcopter arrives on the vertical of the base obviously it stops in hovering but swings on the sides. Is this oscillation normal?

Regards

Re: RTB mode
« Reply #8 on: September 30, 2018, 06:32:04 pm »
If you are using a DJI GPS, there is a known issue.  It oscillates east west about 4 seconds per cycle or so when doing position hold in many GPS modes like PH, VR, RTB-Hold, probably GPS Assisted modes, etc.  Are you using DJI GPS and is the oscillation east-west?  For me, the oscillation is worse or better depending on the direction of the quad.  I recall it being worse when the quad is pointing north.

Here is work around firmware that is compatible with 16.09 (and source code for you to build your own for other versions).  No need to erase or change settings.  Just flash the firmware.
https://forum.librepilot.org/index.php?topic=3012.msg21154#msg21154

startrek66

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Re: RTB mode
« Reply #9 on: September 30, 2018, 07:30:57 pm »
I do not think I bought a Dji GPS. The seller wrote that it was set up for the Pixhawk. I attach a photo of the card. I saw these fluctuations today for the first time. With the VR mode there are absolutely no. these oscillations have appeared with RTB mode. I made a video




« Last Edit: October 02, 2018, 08:25:25 am by startrek66 »

startrek66

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Re: RTB mode
« Reply #10 on: October 02, 2018, 08:26:17 am »
link video


Re: RTB mode
« Reply #11 on: October 02, 2018, 03:52:19 pm »
I don't see a problem there.  Is it visible in FPV view maybe?

startrek66

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Re: RTB mode
« Reply #12 on: October 02, 2018, 04:20:20 pm »
I don't see a problem there.  Is it visible in FPV view maybe?
Probably if you look at the video on smartphone the oscillations are not seen very much. however, I also have the footage in FPV that I will send.
Thank you

Re: RTB mode
« Reply #13 on: October 02, 2018, 05:56:47 pm »
How long per cycle of the oscillation?  One version of the east-west oscillation is a position oscillation that happens every 4 seconds or so.  The other version is an attitude oscillation that happens quicker than once a second.

Do you have your high current wire pairs all twisted properly?  I can imagine a reason this happens that is related to PDB to ESC wire pair not being twisted into a cable.

To know more about the problem, it would be good to test VR-hover and RTB-hover on the same day at roughly the same place on the same flight, and rotate while hovering to see if it is worse in some directions.  Maybe RTB to hover, rotate in RTB hover, throttle stick in center, switch to VR, rotate in VR hover.

- same day same place same flight in case it is related to wind or battery wiring twists for that flight
- rotating to see if it is different when pointing in some directions because I have seen different versions of the east-west oscillation that also happen with OP GPSv9

Wire sets to twist:
- battery to connector
- connector to PDB
- PDB to ESC
- ESC to motor

All this because I know that PH hover and VR hover use the same code and must act the same way.  I suspect that RTB hover also uses the same code and if it does, it should act the same as VR hover.

startrek66

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Re: RTB mode
« Reply #14 on: October 03, 2018, 12:15:09 am »
This is the video.
Start con VR mode then engage RTB (at 00:07). At 00:47 start oscillations (sud-nord+ west-east)over the base. Disengage RTB, engage VR and Landing.
VR mode is asoldly without oscillations when I leave the power stick at 50%. I do not understand, if as you say RTB hold uses the same code of VR, the reason for the oscillations. I just twisted the ESC cables. It should not be necessary to twist other cables if until today the mode hold position with GPS works well and without oscillations


« Last Edit: October 03, 2018, 12:31:56 am by startrek66 »