Mirror/betaflight
1
0
Fork 0
mirror of https://github.com/betaflight/betaflight.git synced 2025-07-21 15:25:36 +03:00
Code Issues Wiki Activity

Added explanation as to why fixed dT is used in PID calculation. (#5737)

Browse source
This commit is contained in:
Michael Keller 2018-04-21 20:21:35 +12:00 • committed by Andrey Mironov
parent 6e44173f86
commit 8e152f3259
1 changed files with 5 additions and 1 deletions
Download patch file Download diff file Expand all files Collapse all files

6
src/main/flight/pid.c
View file

@ -614,7 +614,11 @@ void pidController(const pidProfile_t *pidProfile, const rollAndPitchTrims_t *an
// no transition if relaxFactor == 0 // no transition if relaxFactor == 0
float transition = relaxFactor > 0 ? MIN(1.f, getRcDeflectionAbs(axis) * relaxFactor) : 1; float transition = relaxFactor > 0 ? MIN(1.f, getRcDeflectionAbs(axis) * relaxFactor) : 1;
// Divide rate change by deltaT to get differential (ie dr/dt) // Divide rate change by dT to get differential (ie dr/dt).
// dT is fixed and calculated from the target PID loop time
// This is done to avoid DTerm spikes that occur with dynamically
// calculated deltaT whenever another task causes the PID
// loop execution to be delayed.
const float delta = ( const float delta = (
dynCd * transition * (currentPidSetpoint - previousPidSetpoint[axis]) - dynCd * transition * (currentPidSetpoint - previousPidSetpoint[axis]) -
(gyroRateDterm[axis] - previousGyroRateDterm[axis])) / dT; (gyroRateDterm[axis] - previousGyroRateDterm[axis])) / dT;