I used this plugin recently and experienced much pain because the plugin adjusted INS_GYRO_FILTER from the default of 20 up to 46. I had a large noise peak at 46 and so I found that the quadcopter twitched all over the place.
The 20Hz warning message no longer appears in Mission Planner, at least in my setup.
IMO, the first thing anyone should do before using this plugin (which I think is useful) is to analyse the IMU noise to set a dynamic notch filter. There is no point setting anything else without this out of the way first.
On a smaller multirotor it will be an oscillating mess with the gyro filter set at default. You could not fly it to acquire the data needed to set the notch filter.
I see it now, but the original version had a window pop up which is much more effective at alerting the user to something important. That said, ultimately it is my fault for not reading the text on the initial params page properly.
In preparation for an autotune, I noticed the new plug-in in Mission Planner and thought it might’ve replaced the need for the spreadsheet. …And it does! Yay. Thanks!
Also the spreadsheet is updated, and hopefully soon the Initial Parameters in MissionPlanner will be updated too.
The only important change is a parameter name-change, no changes to formulas to calculations.
Just for checking purposes, I entered my prop size and cell count into the spreadsheet and compared against what has been initially set using Mission Planner’s Initial Parameters Plugin. For all values I got the same numbers, with the exception of ATC_ANG_YAW_P. After using the plugin via Mission Planner, I currently have 4.5 for my parameter. Using the calculator, I get 2.5:
When I try to replace “4.5” with the value “2.5” I get a warning that "ATC_ANG_YAW_P value is out of range. Do you want to continue?"
So I left it at 4.5.
the initial parameters do not take into consideration the number of blades. Do you think it affects the initial flying experience? for example, 3 blades 11x4.5 and 2 blades 11x4.5.
There won’t be a big difference and tuning will sort it out.
The Accel values are not super-critical, the thrust expo can be adjusted later if it gives you trouble.
As an example for a QuadX8 (octaquad) with 2 motors on each arm, you still just put in the individual prop size in inches. You don’t try to halve or double it just because there’s 2 props in coax configuration on each arm.
If you need to adjust MOT_THST_EXPO
set too high you can see instability at low throttle
set too low you can see instability at high throttle
MOT_THST_HOVER will probably be more affected by weight (or weight changes) rather than slight variations in MOT_THST_EXPO. If you do have to change MOT_THST_EXPO a lot I would examine attitude control in logs and probably rerun Autotune.
Ensure you have MOT_BAT_VOLT_MAX and MOT_BAT_VOLT_MIN set correctly.
You could alter it, but setting your failsafe to 3.2v per cell is risky and the battery may have a short life and there may not be the capacity remaining to complete any failsafe action.
Is it Lipo or LIon?
Unless you’ve got some special battery I wouldnt deviate from the standard values.
If you think you will get some significant extra flight time by lowering the failsafe and MOT_BAT_MIN - I think that would be a mistake.
Like running you car fuel tank to empty before you look for somewhere to fill up - you probably wont make it.
EDIT
If you do have a non-standard battery, then definitely set you values as required.
The spreadsheet and Inititial Parameters in MissionPlaner are just to give a good chance of getting off the ground without having to figure out what to change yourself.
If we are using different sizes of propellers (such as at a tricopter), what is the proper way to use the Initial Parameters Calculator or/and the spreadsheet?
Probably just average the size of the props if they are not too dissimilar.
You can always adjust MOT_THST_EXPO later
set too high you can see instability at low throttle
set too low you can see instability at high throttle
The filter frequencies are not so critical until you get into very small props.
In a lot of cases you can stick with nice easy numbers for INS_GYRO_FILTER / _FLT values like
20/10 , 30/15 or 40/20 and so on.
So put in your smallest prop size, make note of the values
Put in your largest prop size, note the values
Choose INS_GYRO_FILTER rounded to nearest 10, half that for FLT values.
