Hi,
we have a large hexacopter (22"inch props), about 12kg.
tmotor and esc combo set with alpha esc
We have set the manual tuning to have a safe flight and we would like to finish the tune with the autotune.
but… we have some fear about autotune previous tune conditions.
in the log have 2 flights, auto flight and manual flight with manual inputs to test the pids.
this tuning will be good enough to make a safe autotune?
thanks
Your vibrations looks high. You could search for solutions to reduce on wiki and forum.
yes, we are working on it. mounting the autopilot on thicker carbon plate more rigid.
the question its about pid tuning if these tuning is good enough to make a safe autotune.
Not much point if the vibe levels are high.
Do not autotune if vibrations are high or there are other issues, you might destroy your vehicle.
I advise you to read some more on vibrations and read section one of the How to methodically configure and tune arducopter.
After that you can start ArduPilot methodic configuratior at step file 17.
We are working in reduce the vibe level with 3dprint damper mount for cube (the tilted one silenblocks model, not the cheap and old 3dprint models)
the vibes overall have a great reduction but… we still have moderate vibe levels in x and y axis. in z the vibes are ok
pictures of Y and Z vibe axis with the damper mount for FC.
how we can improve the Y vibes?
with these mount, we have noticed that the current pid tuning are less accurate, must be done some pid tuning to improve the overall tuning of the craft
the latest .bin file of the test
X and Y axis vibe come from wiring problem?
I agree it’s probably the wiring, especially all those Servo wires in a bunch. They need to be quite flexible near the flight controller and secured to the frame (or base plate) so you dont have the weight of all the wires pulling on the FC.
For T-Motor Alpha ESCs you need these:
MOT_PWM_MIN,1100
MOT_PWM_MAX,1940
and retest for
MOT_SPIN_ARM
MOT_SPIN_MIN
You might need to increase expo to 0.6, but more flights will tell.
Set logging:
LOG_BITMASK,180222
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,4
Set the Harmonic Notch filter:
INS_HNTCH_ENABLE,1
INS_HNTCH_MODE,1
INS_HNTCH_REF,0.15
INS_HNTCH_FREQ,40
INS_HNTCH_BW,20
INS_HNTCH_FM_RAT,0.7
and it can be refined after the next flight.
I would use the VTOL Quicktune script.
Thanks for the update, i will make more flights with these updates.
setting up the notch filter as you says and logging options to improve it with the data of next flights
our main goal now its improve the wiring system in the servo outputs to make them more flexible and dont transmit any load to the fc.
i will try too the quicktune
Hi again,
first, thanks for your advice.
i have setup the notch filter as you says and make the quicktune script.
the tune have improved a little and the flight its very smooth.
at the moment, our main issue its the vibe levels, main in the Y and X axis, and we are unable to lower these levels.
we use the damper mount with red silentblocks. the z vibes are at reasonable levels but the x and y are a little high.
please can you recommend us some notch filter corrections?
thanks
Have you loosened cables more ?. Maybe you could share a new photo and we see something you don’t.
Zipping cables close to pins creates more tension. The problem is probably still about cable tension and something holding the damper.
there are loose some wires, even remove some payload wires to test before mount payloads.
apparently, there are not wires pulling the damper mount. the signal wires of the motor are soft wires of silicon.
our issue maybe came from the carbon plate under the cube, its a carbon plane attached on main frame with 4 alu spacers
we suspect that this plate could amplify the vibes on the frame. we will machine a new carbon plate more thick to test it.
No doubt that is contributing to the problem. It’s too thin and poorly supported. Why use it? A large X8 I worked on had a PDB plate like that. The solution was to get rid of it.
Mass is your friend when it comes to vibration damping.
its our suspect about the origin of the vibes
we use it because its the original part came from this frame.
but…
with these results and we try a lot of solutions:
and… we have some high vibe levels yet.
the next test will be a custom made flight controller carbon plate with a thicker plate, about 3mm and reinforced alu spacers
…
Why use it at all?
what would be your solution¿
In this work you talk about, how did you proceed to put the autopilot?
hard mounting on a custom rigid carbon plate?
Attach it directly to the base plate
if we attach the cube to the main base plate, where we attach the main pdb and the power wires of the motors?
its a solution we think time ago
