Setting the input shaping parameters


I have a very big doubt, i have done my PID tuning using the 10000MAH battery (2.5 kg) 12S, without any loads. I wanted to change the battery to 22000MAH(5 Kg) or 16000MAH battery(4kg). Do you think i must do this:

For aircraft designed to carry large directly mounted payloads, the maximum values of ATC_ACCEL_P_MAX, ATC_ACCEL_R_MAX and ATC_ACCEL_Y_MAX should be reduced based on the minimum and maximum takeoff weight (TOW):

After changing the battery i would like to carry one kg weight and do delivery.

Hoping to hear your expertise and experience.

You dont say what the weight of the copter is, but let’s say it’s 3kg and the battery used for tuning was the 2.5kg one.
Then you fit the 5kg battery and the 1kg payload.

new ATC_ACCEL_P_MAX = old ATC_ACCEL_P_MAX x ((3+2.5) / (3+5+1))

new ATC_ACCEL_P_MAX = old ATC_ACCEL_P_MAX x 0.611

Never go below half of the Autotuned/ideal ATC_ACCEL_MAX values even if the maths works out that way.
The values are not too critical though, so can be rounded to the nearest 1000, the decimal places wont make a difference. So if you have ATC_ACCEL_P_MAX = 62387.25 and you calc a new value for increased payload of 38118.6 then you can just call it 38000, or even round it up to 39000 and it will suit the other battery too.


Thank you so much Shawn.

Can you please tell me what would be the effect of this… If input shaping is not performed.

Should i have to tune again or i can just change the parameter.

Can you also please tell me if there are anything that i need to worry about.

You dont tune again - just change the accel parameters.
If you are frequently flying without payload, or varying payloads, you could even have a couple of different .param files ready to load (made up samples here)





There’s no great disadvantage to always flying with the calculated heavy payload values though, the copter will just be a bit less “snappy”

The other input shaping parameter to check is
The default value makes the copter very responsive to RC input, which is usually not good for a large copter, I always use around 0.2 or 0.22 but you can even go to 0.3 for some very large copters.