Re: GPS assist and Heli
« Reply #90 on: January 11, 2018, 02:08:36 am »
As far as I know, the accel cal has never used a home location, but your point that it could use one for best accuracy is true...

I think this is because CC3D and Basic don't need it (no home location) and INS13 allows calibration with home location values farther up the stack and that could take it into account.

It does matter what orientation the board has.  That is what it asks you for.  If you do it with it still mounted in the vehicle, just hold the vehicle so the board is in the desired orientation.

I would not rip it out just to put in in the freezer.  Most people just do it from cool room temperature to full warm temperature.  a 10C difference is all that is required IIRC.  If above the equator, maybe just put it outside in the winter for a few minutes...


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Re: GPS assist and Heli
« Reply #91 on: January 11, 2018, 03:49:10 am »
It would save me a lot of trouble and time if I can leave it mounted inside heli while doing these calibrations (thermo and accelerometer).
Its minus 5 C outside today so I will try that.
Also will try just keep the virtual orientation setting but placing the board in the positions GCS asks me.

In the previous accelerometer calibration i have been flying with, I did it with the virtual orientation set, but placing the whole heli in the positions GCS asked me.
This should make a difference... maybe this is one reason why Attitude is confused...

Re: GPS assist and Heli
« Reply #92 on: January 11, 2018, 04:59:54 am »
for accel calibration:
Make sure the board orientation is as requested, as exactly as possible and as motionless as possible.

Heli landing gear on floor, on wall (joint with floor for completely locked in orientation), ceiling upside down...  The motionless part is probably the hardest issue.  Good luck.

for thermal calibration:
The main issue is that it needs to be completely motionless for the whole time.  Afterward, you may want to look at gyro scope and notice there is a slight bias now.  The gyro noise is not centered exactly on zero.  To fix this, just make sure to run the gyro calibration again, after the thermal calibration.  The scope will show you that it is fixed now.
« Last Edit: January 11, 2018, 05:31:09 am by TheOtherCliff »


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Re: GPS assist and Heli
« Reply #93 on: January 12, 2018, 09:12:57 am »
Ah thats a great idea to do floor, wall, ceiling for support.
I might need to redo it later, but I think I got the thermo calibration okay.
It was tied down heavily and I applied a hair dryer gently blowing hot air over the frame.
It said the range was some 60 degrees range from 3-4 C up to over 60.
I am still waiting for the delivery of my main shaft before I can do any flying.


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Re: GPS assist and Heli
« Reply #94 on: Today at 10:42:36 am »
Hehe, very happy now the main shaft arrived.

So, i have already repaired/completed the following:
. Both main rotor blades now balanced with each other
. Rotor blade tracking now okay
. Swashplate levelling, smooth and horizontal all from Max down to Min position
. Collective pitch angles of blades now set okay for Hover, Max and Min (stock Align angles)
. Throttle curves for recommended Head speed now set okay

This time I want to go about the 'Hover without drift' differently than from before, that was by settings of the virtual rotation of the board.
(Helis need compensate the tail rotor thrust giving a roll angel to the whole craft)
Now, I want to adjust the swash plate angle instead to accomplish the same end.
Reason is to easier pilot take off and landings in Attitude mode (especially when flying fpv) and a more consistent behavior of craft when flying in rate and attitude modes.

So, to adjust the swash tilt angle, there are some 3 ways of doing it (personally I prefer option 3).
1. Using GCS Vehicle, Helicopter, Swashplate levelling:

Maybe most user friendly, but has many process steps we don't need just for tilting swash to stable hover.

2. Using the Output tab

This is very clear and good overview and don't have unnecessary process steps for our purposes, but it involves the scary part of motor also be active. You can unplugg at least 2 wires to the motor to avoid this though.

3. Using Settings Actuator ChannelMax Neutral and Min

This is not a user friendly interface but it does the job - smack on.
Just enter a new number and press the red upward looking arrow button to save to the board.

One useful thing to know is which servo to adjust when using your selected option.
For most trex450 size helis the servo swash plate setup will be:

                   West servo | East servo | South servo

Option1:   1                3                2
Option2:   Roll1         Elevator   Roll2
Option3:  [ 0]           [ 1]             [ 2]

Now, you only need to fly the heli (in Rate stabilization and Basic AttEstAlg)
and adjust the 3 servos so you get a hover without drifting.
Just adjust the Min, Max and Neutral values equally much. For example drifting to the right - then increase (if not channel reversed, if so then decrease it) the East servo by 25 units increments for each Min, Max and Neutral value. Then fly it and see the result. Adjust again.

When successfully completed, the swash plate will be tilted in such a way that the heli is hovering without drift. Furthermore, it will keep this tilt all through to travel of collective pitch from min to max.

That's what I'm going to do now.