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Code Issues Wiki Activity

Fix bugs in gain scaling; Allow gain scaling for NAV PID

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This commit is contained in:
Konstantin Sharlaimov (DigitalEntity) 2017-09-05 23:52:42 +10:00
parent 89e86bbc8b
commit 8666edc80e
3 changed files with 24 additions and 15 deletions
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22
src/main/navigation/navigation.c
View file

@ -1330,13 +1330,13 @@ static void navProcessFSMEvents(navigationFSMEvent_t injectedEvent)
// Implementation of PID with back-calculation I-term anti-windup
// Control System Design, Lecture Notes for ME 155A by Karl Johan Åström (p.228)
// http://www.cds.caltech.edu/~murray/courses/cds101/fa02/caltech/astrom-ch6.pdf
float navPidApply2(pidController_t *pid, const float setpoint, const float measurement, const float dt, const float outMin, const float outMax, const pidControllerFlags_e pidFlags)
float navPidApply3(pidController_t *pid, const float setpoint, const float measurement, const float dt, const float outMin, const float outMax, const pidControllerFlags_e pidFlags, const float gainScaler)
{
float newProportional, newDerivative;
float error = setpoint - measurement;
/* P-term */
newProportional = error * pid->param.kP;
newProportional = error * pid->param.kP * gainScaler;
/* D-term */
if (pidFlags & PID_DTERM_FROM_ERROR) {
@ -1350,19 +1350,19 @@ float navPidApply2(pidController_t *pid, const float setpoint, const float measu
pid->last_input = measurement;
}
newDerivative = pid->param.kD * pt1FilterApply4(&pid->dterm_filter_state, newDerivative, NAV_DTERM_CUT_HZ, dt);
newDerivative = pid->param.kD * pt1FilterApply4(&pid->dterm_filter_state, newDerivative, NAV_DTERM_CUT_HZ, dt) * gainScaler;
if (pidFlags & PID_ZERO_INTEGRATOR) {
pid->integrator = 0.0f;
}
/* Pre-calculate output and limit it if actuator is saturating */
const float outVal = newProportional + pid->integrator + newDerivative;
const float outVal = newProportional + (pid->integrator * gainScaler) + newDerivative;
const float outValConstrained = constrainf(outVal, outMin, outMax);
/* Update I-term */
if (!(pidFlags & PID_ZERO_INTEGRATOR)) {
const float newIntegrator = pid->integrator + (error * pid->param.kI * dt) + ((outValConstrained - outVal) * pid->param.kT * dt);
const float newIntegrator = pid->integrator + (error * pid->param.kI * gainScaler * dt) + ((outValConstrained - outVal) * pid->param.kT * dt);
if (pidFlags & PID_SHRINK_INTEGRATOR) {
// Only allow integrator to shrink
@ -1378,6 +1378,12 @@ float navPidApply2(pidController_t *pid, const float setpoint, const float measu
return outValConstrained;
}
float navPidApply2(pidController_t *pid, const float setpoint, const float measurement, const float dt, const float outMin, const float outMax, const pidControllerFlags_e pidFlags)
{
return navPidApply3(pid, setpoint, measurement, dt, outMin, outMax, pidFlags, 1.0f);
}
void navPidReset(pidController_t *pid)
{
pid->integrator = 0.0f;
@ -2605,9 +2611,9 @@ void navigationUsePIDs(void)
(float)pidProfile()->bank_fw.pid[PID_POS_XY].I / 100.0f,
(float)pidProfile()->bank_fw.pid[PID_POS_XY].D / 100.0f);
navPidInit(&posControl.pids.fw_alt, (float)pidProfile()->bank_fw.pid[PID_POS_Z].P,
(float)pidProfile()->bank_fw.pid[PID_POS_Z].I,
(float)pidProfile()->bank_fw.pid[PID_POS_Z].D);
navPidInit(&posControl.pids.fw_alt, (float)pidProfile()->bank_fw.pid[PID_POS_Z].P / 9.80665f,
(float)pidProfile()->bank_fw.pid[PID_POS_Z].I / 9.80665f,
(float)pidProfile()->bank_fw.pid[PID_POS_Z].D / 9.80665f);
}
void navigationInit(void)

16
src/main/navigation/navigation_fixedwing.c
View file

@ -110,22 +110,24 @@ static void updateAltitudeVelocityAndPitchController_FW(timeDelta_t deltaMicros)
const float estSPE = (posControl.actualState.pos.V.Z / 100.0f) * GRAVITY_MSS;
const float estSKE = 0.0f;
// speedWeight controls balance between potential and kinetic energy used for pitch controller
// speedWeight = 1.0 : pitch will only control airspeed and won't control altitude
// speedWeight = 0.5 : pitch will be used to control both airspeed and altitude
// speedWeight = 0.0 : pitch will only control altitude
const float speedWeight = 0.0f; // no speed sensing for now
const float wSKE = speedWeight;
const float wSPE = 1.0f - speedWeight;
const float demSEB = demSPE * wSPE - demSKE * wSKE;
const float estSEB = estSPE * wSPE - estSKE * wSKE;
const float demSEB = demSPE * (1.0f - speedWeight) - demSKE * speedWeight;
const float estSEB = estSPE * (1.0f - speedWeight) - estSKE * speedWeight;
// SEB to pitch angle gain to account for airspeed
const float pitchGainInv = GRAVITY_MSS; // GRAVITY_MSS * airspeed;
// SEB to pitch angle gain to account for airspeed (with respect to specified reference (tuning) speed
const float pitchGainInv = 1.0f / 1.0f;
// Here we use negative values for dive for better clarity
const float maxClimbDeciDeg = DEGREES_TO_DECIDEGREES(navConfig()->fw.max_climb_angle);
const float minDiveDeciDeg = -DEGREES_TO_DECIDEGREES(navConfig()->fw.max_dive_angle);
// PID controller to translate energy balance error [J] into pitch angle [decideg]
float targetPitchAngle = navPidApply2(&posControl.pids.fw_alt, demSEB, estSEB, US2S(deltaMicros), minDiveDeciDeg, maxClimbDeciDeg, 0) / pitchGainInv;
float targetPitchAngle = navPidApply3(&posControl.pids.fw_alt, demSEB, estSEB, US2S(deltaMicros), minDiveDeciDeg, maxClimbDeciDeg, 0, pitchGainInv);
targetPitchAngle = pt1FilterApply4(&velzFilterState, targetPitchAngle, NAV_FW_PITCH_CUTOFF_FREQENCY_HZ, US2S(deltaMicros));
// Reconstrain pitch angle ( >0 - climb, <0 - dive)

1
src/main/navigation/navigation_private.h
View file

@ -296,6 +296,7 @@ extern navigationPosControl_t posControl;
/* Internally used functions */
float navPidApply2(pidController_t *pid, const float setpoint, const float measurement, const float dt, const float outMin, const float outMax, const pidControllerFlags_e pidFlags);
float navPidApply3(pidController_t *pid, const float setpoint, const float measurement, const float dt, const float outMin, const float outMax, const pidControllerFlags_e pidFlags, const float gainScaler);
void navPidReset(pidController_t *pid);
void navPidInit(pidController_t *pid, float _kP, float _kI, float _kD);
void navPInit(pController_t *p, float _kP);