Help! Throttle Not Accurately Tracking

[samtkeen]

Hello,
I am having this issue where my throttle in iNavFlight and my blackbox is not tracking properly. The throttle in the blackbox (RC Command) is tracking lower than what the reciever tab is recieving in iNav reciever tab. Originally iNavFlight recieved a range of 987-2011, i applied a 98% weight in the mixer to recieve a range of 1000-2000 for simplicity for the test. I also set idle power to 0% so we can actually see what 0 throttle tracks at in the blackbox
Test:
key: input in reciever tab of iNavFlight --> tracking of RC command throttle in blackbox

1. Arm to get base throttle -> tracks at 1000 (0%)
2. move to 1300/30% (hover throttle) --> tracks at 1196 (23%)
3. move to 1500/50% (mid throttle) --> tracks at 1377 (44%)
4. move to 2000/100% (max throttle) --> tracks at 1850 (100%)

Equipment

• FC - MatekF722 PX
• firmware - iNav 3.0.1
• Radio - FrSKY Taranis X9 Lite
• Reciever - FrSky Archer RS

Is there a setting i need to change or something i need to do to make sure it tracks correctly?
if you need anymore details or questions please ask!

Attached is the blackbox recording

Reciver Tab for reference

 

[samtkeen]

I attempted to change the max throttle to 2000 but the issue still persists.

Method CLI command:
set max_throttle = 2000
save

kept the same 98% weighting on radio and it now tracks at:
30%/1300 --> 1222 (22%)
50%/1500 --> 1449 (45%)
100%/2000 --> 2000(100%)
so although max and min throttle track why is it all jumbled in the middle? NOTE all throttle expo's are set to 0

throttle params:

max_throttle = 2000
Allowed range: 1000 - 2000
throttle_scale = 1.000
Allowed range: 0 - 1
throttle_idle = 0.000
Allowed range: 0 - 30
failsafe_throttle = 1000
Allowed range: 1000 - 2000
failsafe_throttle_low_delay = 0
Allowed range: 0 - 300
fw_min_throttle_down_pitch = 0
Allowed range: 0 - 450
3d_deadband_throttle = 50
Allowed range: 0 - 200
airmode_throttle_threshold = 1300
Allowed range: 1000 - 2000
throttle_tilt_comp_str = 0
Allowed range: 0 - 100

 

[Bricks]

Have you calibrated your transmitter sticks?

 

[samtkeen]

unfortunately after calibrating the problem still persists.

Here is more data if it helps:

rc command bottoms out at 1000 so that why its unaffected

 

[PsyBorg]

unfortunately after calibrating the problem still persists.

Here is more data if it helps:
View attachment 206934
rc command bottoms out at 1000 so that why its unaffected

There is a setting in the main section of open tx where you can specify step values for the sticks. Basically how big each increment it will change with stick movement. Unless Inav MUST have those exact values (which I doubt) then that range looks pretty linear and should be fine. The only thing you may have to do if you need better low end resolution is to set a throttle curve in the radio. But to be honest most quads wont lift off or even get light before ~20% throttle or more.

 

[samtkeen]

is it a multiplier or something else? im trying to raise the RC command to match the Inav config values so a multiplier seems a bit difficult as the error gets smaller.

ill give it a go, would that be on the radio itself or the openTX companion? also any more info on where to find it or what specifically the setting is called please?

If it doesnt work i will record the value on the radio (-100 to 100) and see if that also gives any more info

 

[PsyBorg]

is it a multiplier or something else? im trying to raise the RC command to match the Inav config values so a multiplier seems a bit difficult as the error gets smaller.

ill give it a go, would that be on the radio itself or the openTX companion? also any more info on where to find it or what specifically the setting is called please?

If it doesnt work i will record the value on the radio (-100 to 100) and see if that also gives any more info

I think I was in error.. I just looked and in the model config page 2 there was a setting for "trim Step" values that have fine medium and course options.

It will take time but you can exactly match those numbers by going to page 7 in the model config and making a custom curve then assign it to throttle. Set the type to Custom set the count to 11. Make sure smooth box is unchecked then you have the fun of manipulating the points to match each rows desired output.

I would make a new model and work it out on that then just copy those same numbers into your actual model memory.

 

[samtkeen]

okay so make a custom curve to compensate, think i can do that!

What do you think is causing it though? because although the curve will likely be a workaround for the issue am i right in saying this shouldnt happen normally? just concious of if there is an underlying bug/issue, id want to fix it in case it affects stuff im not aware of

 

[samtkeen]

graph and radio data for further analysis if it helps

 

[PsyBorg]

graph and radio data for further analysis if it helps

Simply put software programmed value vs actual physical values. the tolerances in electronics at our level will never be stable enough nor accurate enough to hit exact numbers consistently.

Look at analog joysticks vs hall effect sensored ones. Most times you have to set a dead band on analog system specially the more they age and wear out where a hall effect can get closer to an actual set point and stay more stable and even so is hard to get perfect even numbers like in programming.