STATIC_UNIT_TESTED int16_t pidLuxFloatCore(int axis, const pidProfile_t *pidProfile, float gyroRate, float angleRate)
{
static float lastRateForDelta[3];
SET_PID_LUX_FLOAT_CORE_LOCALS(axis);
const float rateError = angleRate - gyroRate;
// -----calculate P component
float PTerm = luxPTermScale * rateError * pidProfile->P8[axis] * PIDweight[axis] / 100;
// Constrain YAW by yaw_p_limit value if not servo driven, in that case servolimits apply
if (axis == YAW) {
if (pidProfile->yaw_lpf_hz) {
PTerm = pt1FilterApply4(&yawFilter, PTerm, pidProfile->yaw_lpf_hz, getdT());
}
if (pidProfile->yaw_p_limit && motorCount >= 4) {
PTerm = constrainf(PTerm, -pidProfile->yaw_p_limit, pidProfile->yaw_p_limit);
}
}
// -----calculate I component
float ITerm = lastITermf[axis] + luxITermScale * rateError * getdT() * pidProfile->I8[axis];
// limit maximum integrator value to prevent WindUp - accumulating extreme values when system is saturated.
// I coefficient (I8) moved before integration to make limiting independent from PID settings
ITerm = constrainf(ITerm, -PID_MAX_I, PID_MAX_I);
// Anti windup protection
if (rcModeIsActive(BOXAIRMODE)) {
if (STATE(ANTI_WINDUP) || motorLimitReached) {
ITerm = constrainf(ITerm, -ITermLimitf[axis], ITermLimitf[axis]);
} else {
ITermLimitf[axis] = ABS(ITerm);
}
}
lastITermf[axis] = ITerm;
// -----calculate D component
float DTerm;
if (pidProfile->D8[axis] == 0) {
// optimisation for when D8 is zero, often used by YAW axis
DTerm = 0;
} else {
float delta;
if (pidProfile->deltaMethod == PID_DELTA_FROM_MEASUREMENT) {
delta = -(gyroRate - lastRateForDelta[axis]);
lastRateForDelta[axis] = gyroRate;
} else {
delta = rateError - lastRateForDelta[axis];
lastRateForDelta[axis] = rateError;
}
// Divide delta by targetLooptime to get differential (ie dr/dt)
delta /= getdT();
// Filter delta
if (pidProfile->dterm_notch_hz) {
delta = biquadFilterApply(&dtermFilterNotch[axis], delta);
}
if (pidProfile->dterm_lpf_hz) {
if (pidProfile->dterm_filter_type == FILTER_BIQUAD) {
delta = biquadFilterApply(&dtermFilterLpf[axis], delta);
} else {
// DTerm delta low pass filter
delta = pt1FilterApply4(&deltaFilter[axis], delta, pidProfile->dterm_lpf_hz, getdT());
}
}
DTerm = luxDTermScale * delta * pidProfile->D8[axis] * PIDweight[axis] / 100;
DTerm = constrainf(DTerm, -PID_MAX_D, PID_MAX_D);
}
#ifdef BLACKBOX
axisPID_P[axis] = PTerm;
axisPID_I[axis] = ITerm;
axisPID_D[axis] = DTerm;
#endif
GET_PID_LUX_FLOAT_CORE_LOCALS(axis);
// -----calculate total PID output
return lrintf(PTerm + ITerm + DTerm);
}
// Betaflight pid controller, which will be maintained in the future with additional features specialised for current (mini) multirotor usage.
// Based on 2DOF reference design (matlab)
void pidBetaflight(const pidProfile_t *pidProfile, uint16_t max_angle_inclination, const rollAndPitchTrims_t *angleTrim, const rxConfig_t *rxConfig)
{
float errorRate = 0, rP = 0, rD = 0, PVRate = 0;
float ITerm,PTerm,DTerm;
static float lastRateError[2];
static float Kp[3], Ki[3], Kd[3], b[3], c[3], rollPitchMaxVelocity, yawMaxVelocity, previousSetpoint[3];
float delta;
int axis;
float horizonLevelStrength = 1;
float tpaFactor = PIDweight[0] / 100.0f; // tpa is now float
initFilters(pidProfile);
if (FLIGHT_MODE(HORIZON_MODE)) {
// Figure out the raw stick positions
const int32_t stickPosAil = ABS(getRcStickDeflection(FD_ROLL, rxConfig->midrc));
const int32_t stickPosEle = ABS(getRcStickDeflection(FD_PITCH, rxConfig->midrc));
const int32_t mostDeflectedPos = MAX(stickPosAil, stickPosEle);
// Progressively turn off the horizon self level strength as the stick is banged over
horizonLevelStrength = (float)(500 - mostDeflectedPos) / 500; // 1 at centre stick, 0 = max stick deflection
if(pidProfile->D8[PIDLEVEL] == 0){
horizonLevelStrength = 0;
} else {
horizonLevelStrength = constrainf(((horizonLevelStrength - 1) * (100 / pidProfile->D8[PIDLEVEL])) + 1, 0, 1);
}
}
// Yet Highly experimental and under test and development
// Throttle coupled to Igain like inverted TPA // 50hz calculation (should cover all rx protocols)
static float kiThrottleGain = 1.0f;
if (pidProfile->itermThrottleGain) {
const uint16_t maxLoopCount = 20000 / targetPidLooptime;
const float throttleItermGain = (float)pidProfile->itermThrottleGain * 0.001f;
static int16_t previousThrottle;
static uint16_t loopIncrement;
if (loopIncrement >= maxLoopCount) {
kiThrottleGain = 1.0f + constrainf((float)(ABS(rcCommand[THROTTLE] - previousThrottle)) * throttleItermGain, 0.0f, 5.0f); // Limit to factor 5
previousThrottle = rcCommand[THROTTLE];
loopIncrement = 0;
} else {
loopIncrement++;
}
}
// ----------PID controller----------
for (axis = 0; axis < 3; axis++) {
static uint8_t configP[3], configI[3], configD[3];
// Prevent unnecessary computing and check for changed PIDs. No need for individual checks. Only pids is fine for now
// Prepare all parameters for PID controller
if ((pidProfile->P8[axis] != configP[axis]) || (pidProfile->I8[axis] != configI[axis]) || (pidProfile->D8[axis] != configD[axis])) {
Kp[axis] = PTERM_SCALE * pidProfile->P8[axis];
Ki[axis] = ITERM_SCALE * pidProfile->I8[axis];
Kd[axis] = DTERM_SCALE * pidProfile->D8[axis];
b[axis] = pidProfile->ptermSetpointWeight / 100.0f;
c[axis] = pidProfile->dtermSetpointWeight / 100.0f;
yawMaxVelocity = pidProfile->yawRateAccelLimit * 1000 * getdT();
rollPitchMaxVelocity = pidProfile->rateAccelLimit * 1000 * getdT();
configP[axis] = pidProfile->P8[axis];
configI[axis] = pidProfile->I8[axis];
configD[axis] = pidProfile->D8[axis];
}
// Limit abrupt yaw inputs / stops
float maxVelocity = (axis == YAW) ? yawMaxVelocity : rollPitchMaxVelocity;
if (maxVelocity) {
float currentVelocity = setpointRate[axis] - previousSetpoint[axis];
if (ABS(currentVelocity) > maxVelocity) {
setpointRate[axis] = (currentVelocity > 0) ? previousSetpoint[axis] + maxVelocity : previousSetpoint[axis] - maxVelocity;
}
previousSetpoint[axis] = setpointRate[axis];
}
// Yaw control is GYRO based, direct sticks control is applied to rate PID
if ((FLIGHT_MODE(ANGLE_MODE) || FLIGHT_MODE(HORIZON_MODE)) && axis != YAW) {
// calculate error angle and limit the angle to the max inclination
#ifdef GPS
const float errorAngle = (constrain(2 * rcCommand[axis] + GPS_angle[axis], -((int) max_angle_inclination),
+max_angle_inclination) - attitude.raw[axis] + angleTrim->raw[axis]) / 10.0f; // 16 bits is ok here
#else
const float errorAngle = (constrain(2 * rcCommand[axis], -((int) max_angle_inclination),
+max_angle_inclination) - attitude.raw[axis] + angleTrim->raw[axis]) / 10.0f; // 16 bits is ok here
#endif
if (FLIGHT_MODE(ANGLE_MODE)) {
// ANGLE mode - control is angle based, so control loop is needed
setpointRate[axis] = errorAngle * pidProfile->P8[PIDLEVEL] / 10.0f;
} else {
// HORIZON mode - direct sticks control is applied to rate PID
// mix up angle error to desired AngleRate to add a little auto-level feel
setpointRate[axis] = setpointRate[axis] + (errorAngle * pidProfile->I8[PIDLEVEL] * horizonLevelStrength / 10.0f);
}
}
PVRate = gyroADCf[axis] / 16.4f; // Process variable from gyro output in deg/sec
// --------low-level gyro-based PID based on 2DOF PID controller. ----------
// ---------- 2-DOF PID controller with optional filter on derivative term. b = 1 and only c can be tuned (amount derivative on measurement or error). ----------
// Used in stand-alone mode for ACRO, controlled by higher level regulators in other modes
// ----- calculate error / angle rates ----------
errorRate = setpointRate[axis] - PVRate; // r - y
rP = b[axis] * setpointRate[axis] - PVRate; // br - y
// Slowly restore original setpoint with more stick input
float diffRate = errorRate - rP;
rP += diffRate * rcInput[axis];
// Reduce Hunting effect and jittering near setpoint. Limit multiple zero crossing within deadband and lower PID affect during low error amount
float dynReduction = tpaFactor;
if (pidProfile->toleranceBand) {
const float minReduction = (float)pidProfile->toleranceBandReduction / 100.0f;
static uint8_t zeroCrossCount[3];
static uint8_t currentErrorPolarity[3];
if (ABS(errorRate) < pidProfile->toleranceBand) {
if (zeroCrossCount[axis]) {
if (currentErrorPolarity[axis] == POSITIVE_ERROR) {
if (errorRate < 0 ) {
zeroCrossCount[axis]--;
currentErrorPolarity[axis] = NEGATIVE_ERROR;
}
} else {
if (errorRate > 0 ) {
zeroCrossCount[axis]--;
currentErrorPolarity[axis] = POSITIVE_ERROR;
}
}
} else {
dynReduction *= constrainf(ABS(errorRate) / pidProfile->toleranceBand, minReduction, 1.0f);
}
} else {
zeroCrossCount[axis] = pidProfile->zeroCrossAllowanceCount;
currentErrorPolarity[axis] = (errorRate > 0) ? POSITIVE_ERROR : NEGATIVE_ERROR;
}
}
// -----calculate P component
PTerm = Kp[axis] * rP * dynReduction;
// -----calculate I component.
// Reduce strong Iterm accumulation during higher stick inputs
float accumulationThreshold = (axis == YAW) ? pidProfile->yawItermIgnoreRate : pidProfile->rollPitchItermIgnoreRate;
float setpointRateScaler = constrainf(1.0f - (1.5f * (ABS(setpointRate[axis]) / accumulationThreshold)), 0.0f, 1.0f);
// Handle All windup Scenarios
// limit maximum integrator value to prevent WindUp
float itermScaler = setpointRateScaler * kiThrottleGain;
errorGyroIf[axis] = constrainf(errorGyroIf[axis] + Ki[axis] * errorRate * getdT() * itermScaler, -250.0f, 250.0f);
// I coefficient (I8) moved before integration to make limiting independent from PID settings
ITerm = errorGyroIf[axis];
//-----calculate D-term (Yaw D not yet supported)
if (axis == YAW) {
if (pidProfile->yaw_lpf_hz) PTerm = pt1FilterApply4(&yawFilter, PTerm, pidProfile->yaw_lpf_hz, getdT());
axisPID[axis] = lrintf(PTerm + ITerm);
DTerm = 0.0f; // needed for blackbox
} else {
rD = c[axis] * setpointRate[axis] - PVRate; // cr - y
delta = rD - lastRateError[axis];
lastRateError[axis] = rD;
// Divide delta by targetLooptime to get differential (ie dr/dt)
delta *= (1.0f / getdT());
if (debugMode == DEBUG_DTERM_FILTER) debug[axis] = Kd[axis] * delta * dynReduction;
// Filter delta
if (dtermNotchInitialised) delta = biquadFilterApply(&dtermFilterNotch[axis], delta);
if (pidProfile->dterm_lpf_hz) {
if (dtermBiquadLpfInitialised) {
delta = biquadFilterApply(&dtermFilterLpf[axis], delta);
} else {
delta = pt1FilterApply4(&deltaFilter[axis], delta, pidProfile->dterm_lpf_hz, getdT());
}
}
DTerm = Kd[axis] * delta * dynReduction;
// -----calculate total PID output
axisPID[axis] = constrain(lrintf(PTerm + ITerm + DTerm), -900, 900);
}
// Disable PID control at zero throttle
if (!pidStabilisationEnabled) axisPID[axis] = 0;
#ifdef GTUNE
if (FLIGHT_MODE(GTUNE_MODE) && ARMING_FLAG(ARMED)) {
calculate_Gtune(axis);
}
#endif
#ifdef BLACKBOX
axisPID_P[axis] = PTerm;
axisPID_I[axis] = ITerm;
axisPID_D[axis] = DTerm;
#endif
}
}
