min_TOW / max_TOW what unit are? are grams or kilos

ArduCopter Copter 4.0
1

Hello!

Just to be clear, the min_TOW and max_TOW are expressed in kilograms or grams?

Thanks

2

Are you talking about the Input Shaping Parameter modification?

3

Either, so long as you are consistent.
You could use pounds, kilograms, adult badgers…
The maths will work exactly the same and give the same result for this type of calculation:
new ATC_ACCEL_P_MAX = ATC_ACCEL_P_MAX x (min_TOW / max_TOW)

https://www.theregister.com/Design/page/reg-standards-converter.html
The Reg online standards converter is compiled from units people have actually used in real articles!

4

thanks, you are right, I did the math and of course is the same result… I was very dumb…

Any way, we have made this 21KG hexacopter, to carry on a a 6kg sensor.

it has:
6 x T-Motor P80III 120KV, Aplha ESC integrated (12S)
6 x MF 3016 Props
4 x 6S 30000mah Liion batteries
Drone weight: 11Kg
Drone with 2 batteries (12S 30000mah): 16.2KG
Drone with 4 batteries (12S 60000mah): 21.5KG
Drone with max payload: 28Kg.

I have made autotuning several times, the results are very similar, but the drone keep having a no reliable behavior I dont understand is its over tuning or undertuning. This never have happened to me before, but its true this is our first heavy payload drone.

Here its a video of the last flight and the log., if anyone can give me a hand to understand what its going on will be great. In this log I was trying to go up and down the P and D from roll and pitch looking for a good result.

With soft movements, drone seems to be ok, but if I do a hard roll or pitch, the drone start swinging arround in Loiter. In that moment I change to AltHold and the drone stops and recover.

This is a roll and roll desire from the logs

image
image1638Ă—1008 74.4 KB

Thanks!!

5

You have a problem with quite a significant centre of gravity shift, heavier towards Motor 1 and it has to work a lot harder than the rest.

image
image1667Ă—888 145 KB

image

Z axis vibrations are also getting close to be an issue - see if there is anything you can do to reduce vibrations.

After fixing those, set these and do another test flight - hovering and some gentle movements, AltHold and Loiter.

ATC_RAT_YAW_I,0.08
ATC_RAT_YAW_P,0.8
GPS_GNSS_MODE,65
INS_ACCEL_FILTER,10
INS_HNTCH_ENABLE,1   // write this then refresh params to see the rest
INS_HNTCH_MODE,1
INS_HNTCH_BW,10
INS_HNTCH_FREQ,30
INS_HNTCH_FM_RAT,0.7
INS_HNTCH_HMNCS,3
INS_HNTCH_REF,0.13
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,4
LOG_BITMASK,180222
PILOT_THR_BHV,7   //  spring centred throttle
6

Thanks, I will try it

What do you think about the bouncing on the braking? Did you saw the video? I saw the unbalance in the Logs, but I think can be the batteries that wasn’t very good installed, as I was using just 2 and not the 4 , but as the drone is very light yet, despite of the unbalance, I think the drone should manage it, it has a lot of power, 18KG per motor., and the drone was just 16KG in that flight in the video

Thanks

7

Hello!

Ok, I have restore the cube configuration, to avoid any miss configuration, start from scratch.

I think vibrations are better and weight distribution too, today I have used 4 batteries, 21KG drone.

The result is almost the same, here is the video and the telemetry with the change you have asked me, you can see in the video I almost lose the drone with a gentle pitch movement.

Can this be related to the 4.4.1 release?

Thanks!

8

No, do not try to find software bugs where there are none.

Reduce vibration levels and do a proper tune. Gives you much, much better results than a conspiracy theory about non existent firmware bugs.

2 Likes
9

thanks, Im sorry about the version SW comment, I know you work very hard to give us the new releases, it was just a question, dont get angry :slight_smile: , but I already flew the drone with 4.3.7 a month ago and wasnt this bad, that is why I made that comment. Today I went back to 4.3.7 and restore previews params, hope that can work.

10

hello Shawn, the log I sent has not the data, this is the right one

thanks

11

There is still quite a difference between motor outputs

image
image1657Ă—881 123 KB

That’s not the end of the world, but it is definitely easier to get a good tune when all the motors are working equally.
I would adjust these:

ATC_ACCEL_P_MAX,20000
ATC_ACCEL_R_MAX,20000
ATC_ACCEL_Y_MAX,9000
INS_ACCEL_FILTER,10
INS_HNTCH_FREQ,32
INS_HNTCH_HMNCS,11
INS_HNTCH_REF,0.22

and I didnt notice this earlier: Alpha ESCs !
You will need to change

MOT_PWM_MIN,1100
MOT_PWM_MAX,1940

and recheck your MOT_SPIN_ARM and MOT_SPIN_MIN using MissionPlanner motor test.
This will alter your hover thrust value in the next flight, so you have to readjust:

INS_HNTCH_REF = 0.7 x hover thrust value (approx)
PSC_ACCZ_I = 2 x hover thrust value
PSC_ACCZ_P = 1 x hover thrust value
12

Thanks, I already have this

MOT_PWM_MIN,1100
MOT_PWM_MAX,1940

What do you think about adjust the D on pitch and roll? As this document say, my problem is oscillation.
image

13

So, today I was doing some manual PID, and now drone works pretty much better. Im a little confused because AutoTune give me number too small, now im almots in P 0.2 with pitch and roll, a D of 0.002, very far away from autotune.

here is the log

Let me know your toughs pls

thanks!

here is the last log.