[PopUnoNkoK]

Hi.

I fly a small/simple FPV racer with CC3D and LibrePilot. I really liked setting the quad up and like how it fly.

My father on the other hand flies a simple butt bigger (450) quad with a small camera for aerial photography.
He now has the Naza M Light with GPS.

In GPS mode the Quad uses GPS to hold its position if you let the sticks go so they center.

The problem with this is that it is sometimes hard to find the center for the trottle stick, so the Quad could be "sneaking" up on a higher altitude.

So a couple of questions.

Do you guys think that the CC3D with GPS would be a possible replacement for the Naza M Lite?

How well does Librepilot hold the Quad in position with a good GPS?

Is there a way to Configure LIbrePilot to have Position Hold when you let go of the sticks. Or do I have to have position hold on a switch?

Could I have Altitude hold on a Switch?

Thanks for maintaining a great software!

//Peter

[utoedter]

Hi Peter,

The classic CC3D (these cheap board for 10-15$)  is not able to do GPS Navigation (position hold, waypoints, return to base) , for that you need a more powerfull flight Controller, the Revolution or the Sparky 2.  Position Hold you can realize via the flightmode switch. Im doing the same at the moment with a revolution board, have a look at the wiki, its well described there. 

Udo

[PopUnoNkoK]

Iv read the wiki. If this is the page your thinking about.

https://librepilot.atlassian.net/wiki/display/LPDOC/Position+Hold

However Im not sure what they mean with: "When engaged, PositionHold hold current vehicle position using GPS sensor and without stick interaction."

Does that mean that I can fly around with GPS mode activated and the GPS does not do anything until I center the sticks. OR does it mean that as soon as I hit the Switch the GPS takes over and hold the Quad EVEN if I move the sticks?

Do you think that the GPS hold works well?

And maybe the most important question. Does Altitude hold works well AND does the Trottle stick have to be in the center position in order for Altitude Hold to work?

Thanks for your reply

[utoedter]

Iv read the wiki. If this is the page your thinking about.

https://librepilot.atlassian.net/wiki/display/LPDOC/Position+Hold

However Im not sure what they mean with: "When engaged, PositionHold hold current vehicle position using GPS sensor and without stick interaction."

Does that mean that I can fly around with GPS mode activated and the GPS does not do anything until I center the sticks. OR does it mean that as soon as I hit the Switch the GPS takes over and hold the Quad EVEN if I move the sticks?

Do you think that the GPS hold works well?

And maybe the most important question. Does Altitude hold works well AND does the Trottle stick have to be in the center position in order for Altitude Hold to work?

Thanks for your reply

Hi Peter,

I did yesterday my first Position Hold Flight and noticed the following. When i released the sticks the quad tried to hold the position, normally it shall not move, but in my case it circled around the point where i released the sticks. With stick input you can override that and move to a new postion, as far as i understood the manual, it shall park at the new position when you release the sticks. So it just compensate the drifts when its blown away by the wind. GPS hold works at the moment not well for me, but the reason may be my cheap OP GPS without external magnetometer.  I tried that yesterday with taulabs instead of libre pilot, today im going to try the same with libre pilot.

Udo

[Mateusz]

OR does it mean that as soon as I hit the Switch the GPS takes over and hold the Quad EVEN if I move the sticks?

Holds copter in one place when you release the sticks.

Do you think that the GPS hold works well?

It does work reasonably well if you know what you are doing. It's definitely not DJI connect parts together and press button.
All sensors with no exception must give good data and be calibrated correctly. Typical problems are with magnetometer while in most situations you need external one and twisted power wires etc.. also VTX antenna too close to GPS can cause bad spikes in Ublox module own engine. Altitude hold with Complementary must be also working (normal baro is +-0.5m response). Temp calibration in darkness (baro is light sensitive) and motion less as it does gyro temp at the same time. All these things must be perfect, and if something is not perfect you need to find out what and fix that.

But yes it can work very good.
 

[TheOtherCliff]

...
When i released the sticks the quad tried to hold the position, normally it shall not move, but in my case it circled around the point where i released the sticks.
...

This is usually caused by mag problems.  All the power wire sets must be twisted together.  Battery -> power board.  Power board -> ESC.  ESC -> motor.  Also, for multicopters smaller than 450 it is usually required to have an external mag (GPS/mag).  Even with 450 it is difficult to make it work without an external mag.

[TheOtherCliff]

@PopUnoNkoK

Both LibrePilot and Naza have "deadband" on throttle stick so that as long as it is close to center, it acts like it is exactly in the center.  Naza LED changes blink from double to single in flight to show you when the throttle is centered.  LibrePilot has a larger deadband.

Personally, I leave the ratchet on the throttle stick to help me avoid moving it.

Controlling altitude is something that requires practice, but it is a part of learning to fly.  It may drift up or down even if stick is in the center.  Also flying around you may need to change it to get over / under things or because of ground.

Altitude Hold does lock the altitude to that level, but I think it is inconvenient to switch modes just to change altitude, so I always use Altitude Vario.  One good thing about AV is that it changes altitude slowly.  If you change from 1/2 to 1/4 stick, it slowly comes down rather than dropping fast.

I like the GPS mode called VelocityRoam rather than using say Stab1 with GPS Assist.

One last thing.  You can change the maximum vertical velocity (If I recall correctly):
for GPS modes with System -> Settings -> VtolPathFollowerSettings -> VerticalVelMax
for simple AltitudeVario with System -> Settings -> AltitudeHoldSettings -> ThrustRate
That makes the vertical speed much slower.  I usually set mine to about 2 m/s.