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AP_TECS: Fixes to reset state
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These concern the TAKEOFF flight stage and address #27147.

* Logging metadata fixes
* Disabled continuous TECS reset during takeoff
* Fixed bug in reached_speed_takeoff calculation
* Limited SPDWEIGHT=2 to only first part of takeoff climb
* _post_TO_hgt_offset set to constant
* Takeoff I-gain now defaults to 0 and is used
* Use at least TRIM_THROTTLE during the climb
* Updated description of TECS_TKOFF_IGAIN with new behaviour
* Forced max throttle while below TKOFF_LVL_ALT
* Added throttle constraints in no-airspeed mode

Additionally, set_min_throttle() has been created, that allows one to
set the minimum TECS throttle for the next update_pitch_throttle() loop.
Additionally, the throttle limits system has been reworked. TECS will
receive external throttle limits from Plane and will always take them
into account and respect them.
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@Georacer @tridge
Georacer authored and tridge committed Jul 29, 2024
1 parent 1e6e291 commit b163e13
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Showing 3 changed files with 126 additions and 44 deletions.
148 changes: 104 additions & 44 deletions libraries/AP_TECS/AP_TECS.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -222,7 +222,7 @@ const AP_Param::GroupInfo AP_TECS::var_info[] = {

// @Param: TKOFF_IGAIN
// @DisplayName: Controller integrator during takeoff
// @Description: This is the integrator gain on the control loop during takeoff. When set to 0 then TECS_INTEG_GAIN is used. Increase to increase the rate at which speed and height offsets are trimmed out. Typically values higher than TECS_INTEG_GAIN work best
// @Description: This is the integrator gain on the control loop during takeoff. Increase to increase the rate at which speed and height offsets are trimmed out.
// @Range: 0.0 0.5
// @Increment: 0.02
// @User: Advanced
Expand Down Expand Up @@ -779,7 +779,6 @@ void AP_TECS::_update_throttle_with_airspeed(void)
// ensure we run at full throttle until we reach the target airspeed
_throttle_dem = MAX(_throttle_dem, _THRmaxf - _integTHR_state);
}
_integTHR_state = integ_max;
} else {
_integTHR_state = constrain_float(_integTHR_state, integ_min, integ_max);
}
Expand Down Expand Up @@ -827,7 +826,12 @@ void AP_TECS::_update_throttle_with_airspeed(void)
#endif
}

// Constrain throttle demand and record clipping
constrain_throttle();

}

// Constrain throttle demand and record clipping
void AP_TECS::constrain_throttle() {
if (_throttle_dem > _THRmaxf) {
_thr_clip_status = clipStatus::MAX;
_throttle_dem = _THRmaxf;
Expand All @@ -843,9 +847,7 @@ float AP_TECS::_get_i_gain(void)
{
float i_gain = _integGain;
if (_flight_stage == AP_FixedWing::FlightStage::TAKEOFF || _flight_stage == AP_FixedWing::FlightStage::ABORT_LANDING) {
if (!is_zero(_integGain_takeoff)) {
i_gain = _integGain_takeoff;
}
i_gain = _integGain_takeoff;
} else if (_flags.is_doing_auto_land) {
if (!is_zero(_integGain_land)) {
i_gain = _integGain_land;
Expand Down Expand Up @@ -893,18 +895,6 @@ void AP_TECS::_update_throttle_without_airspeed(int16_t throttle_nudge, float pi
_throttle_dem = nomThr;
}

if (_flight_stage == AP_FixedWing::FlightStage::TAKEOFF) {
const uint32_t now = AP_HAL::millis();
if (_takeoff_start_ms == 0) {
_takeoff_start_ms = now;
}
const uint32_t dt = now - _takeoff_start_ms;
if (dt*0.001 < aparm.takeoff_throttle_max_t) {
_throttle_dem = _THRmaxf;
}
} else {
_takeoff_start_ms = 0;
}
if (_flags.is_gliding) {
_throttle_dem = 0.0f;
return;
Expand All @@ -918,6 +908,8 @@ void AP_TECS::_update_throttle_without_airspeed(int16_t throttle_nudge, float pi
float cosPhi = sqrtf((rotMat.a.y*rotMat.a.y) + (rotMat.b.y*rotMat.b.y));
float STEdot_dem = _rollComp * (1.0f/constrain_float(cosPhi * cosPhi, 0.1f, 1.0f) - 1.0f);
_throttle_dem = _throttle_dem + STEdot_dem / (_STEdot_max - _STEdot_min) * (_THRmaxf - _THRminf);

constrain_throttle();
}

void AP_TECS::_detect_bad_descent(void)
Expand Down Expand Up @@ -1088,17 +1080,17 @@ void AP_TECS::_update_pitch(void)
// @Field: PEW: Potential energy weighting
// @Field: KEW: Kinetic energy weighting
// @Field: EBD: Energy balance demand
// @Field: EBE: Energy balance error
// @Field: EBE: Energy balance estimate
// @Field: EBDD: Energy balance rate demand
// @Field: EBDE: Energy balance rate error
// @Field: EBDE: Energy balance rate estimate
// @Field: EBDDT: Energy balance rate demand + Energy balance rate error*pitch_damping
// @Field: Imin: Minimum integrator value
// @Field: Imax: Maximum integrator value
// @Field: I: Energy balance error integral
// @Field: KI: Pitch demand kinetic energy integral
// @Field: pmin: Pitch min
// @Field: pmax: Pitch max
AP::logger().WriteStreaming("TEC2","TimeUS,PEW,KEW,EBD,EBE,EBDD,EBDE,EBDDT,Imin,Imax,I,KI,pmin,pmax",
// @Field: tmin: Throttle min
// @Field: tmax: Throttle max
AP::logger().WriteStreaming("TEC2","TimeUS,PEW,KEW,EBD,EBE,EBDD,EBDE,EBDDT,Imin,Imax,I,KI,tmin,tmax",
"Qfffffffffffff",
AP_HAL::micros64(),
(double)SPE_weighting,
Expand All @@ -1112,8 +1104,8 @@ void AP_TECS::_update_pitch(void)
(double)integSEBdot_max,
(double)_integSEBdot,
(double)_integKE,
(double)_PITCHminf,
(double)_PITCHmaxf);
(double)_THRminf,
(double)_THRmaxf);
}
#endif
}
Expand Down Expand Up @@ -1172,22 +1164,25 @@ void AP_TECS::_initialise_states(int32_t ptchMinCO_cd, float hgt_afe)
_hgt_dem = hgt_afe;
_hgt_dem_in_prev = hgt_afe;
_hgt_dem_in_raw = hgt_afe;
_TAS_dem_adj = _TAS_dem;
_flags.reset = true;
_post_TO_hgt_offset = _climb_rate * _hgt_dem_tconst;
_flags.underspeed = false;
_flags.badDescent = false;

_post_TO_hgt_offset = _climb_rate_limit * _hgt_dem_tconst; // Replacement prevents oscillating hgt_rate_dem.
_TAS_dem_adj = _TAS_dem;
_max_climb_scaler = 1.0f;
_max_sink_scaler = 1.0f;

_pitch_demand_lpf.reset(_ahrs.get_pitch());
_pitch_measured_lpf.reset(_ahrs.get_pitch());

if (!_flag_have_reset_after_takeoff) {
_flags.reset = true;
_flag_have_reset_after_takeoff = true;
}
}

if (_flight_stage != AP_FixedWing::FlightStage::TAKEOFF && _flight_stage != AP_FixedWing::FlightStage::ABORT_LANDING) {
// reset takeoff speed flag when not in takeoff
_flags.reached_speed_takeoff = false;
_flag_have_reset_after_takeoff = false;
}
}

Expand Down Expand Up @@ -1252,16 +1247,8 @@ void AP_TECS::update_pitch_throttle(int32_t hgt_dem_cm,
_hgt_dem_in = _hgt_dem_in_raw;
}

if (aparm.takeoff_throttle_max != 0 &&
(_flight_stage == AP_FixedWing::FlightStage::TAKEOFF || _flight_stage == AP_FixedWing::FlightStage::ABORT_LANDING)) {
_THRmaxf = aparm.takeoff_throttle_max * 0.01f;
} else {
_THRmaxf = aparm.throttle_max * 0.01f;
}
_THRminf = aparm.throttle_min * 0.01f;

// min of 1% throttle range to prevent a numerical error
_THRmaxf = MAX(_THRmaxf, _THRminf+0.01);
// Update the throttle limits.
_update_throttle_limits();

// work out the maximum and minimum pitch
// if TECS_PITCH_{MAX,MIN} isn't set then use
Expand Down Expand Up @@ -1312,9 +1299,6 @@ void AP_TECS::update_pitch_throttle(int32_t hgt_dem_cm,
// note that this allows a flare pitch outside the normal TECS auto limits
_PITCHmaxf = _land_pitch_max;
}

// and allow zero throttle
_THRminf = 0;
} else if (_landing.is_on_approach()) {
_PITCHminf = MAX(_PITCHminf, aparm.pitch_limit_min);
_pitch_min_at_flare_entry = _PITCHminf;
Expand All @@ -1339,7 +1323,7 @@ void AP_TECS::update_pitch_throttle(int32_t hgt_dem_cm,
}

if (flight_stage == AP_FixedWing::FlightStage::TAKEOFF || flight_stage == AP_FixedWing::FlightStage::ABORT_LANDING) {
if (!_flags.reached_speed_takeoff && _TAS_state >= _TAS_dem_adj) {
if (!_flags.reached_speed_takeoff && _TAS_state >= _TASmin && _TASmin > 0) {
// we have reached our target speed in takeoff, allow for
// normal throttle control
_flags.reached_speed_takeoff = true;
Expand Down Expand Up @@ -1440,3 +1424,79 @@ void AP_TECS::update_pitch_throttle(int32_t hgt_dem_cm,
}
#endif
}

// set minimum throttle override, [-1, -1] range
// it is applicable for one control cycle only
void AP_TECS::set_throttle_min(const float thr_min) {
// Don't change the limit if it is already covered.
if (thr_min > _THRminf_ext) {
_THRminf_ext = thr_min;
}
}

// set minimum throttle override, [0, -1] range
// it is applicable for one control cycle only
void AP_TECS::set_throttle_max(const float thr_max) {
// Don't change the limit if it is already covered.
if (thr_max < _THRmaxf_ext) {
_THRmaxf_ext = thr_max;
}
}

void AP_TECS::_update_throttle_limits() {

// Configure max throttle.

// Read the maximum throttle limit.
_THRmaxf = aparm.throttle_max * 0.01f;
// If more max throttle is allowed during takeoff, use it.
if (aparm.takeoff_throttle_max*0.01f > _THRmaxf
&& (_flight_stage == AP_FixedWing::FlightStage::TAKEOFF || _flight_stage == AP_FixedWing::FlightStage::ABORT_LANDING)
) {
_THRmaxf = aparm.takeoff_throttle_max * 0.01f;
}
// In any case, constrain to the external safety limits.
_THRmaxf = MIN(_THRmaxf, _THRmaxf_ext);

// Configure min throttle.

// If less min throttle is allowed during takeoff, use it.
bool use_takeoff_throttle = _flight_stage == AP_FixedWing::FlightStage::TAKEOFF || _flight_stage == AP_FixedWing::FlightStage::ABORT_LANDING;
use_takeoff_throttle = use_takeoff_throttle && (aparm.takeoff_mode == 1) && (aparm.takeoff_throttle_min != 0);
if ( use_takeoff_throttle ) {
_THRminf = MIN(_THRminf, aparm.takeoff_throttle_min * 0.01f);
}
else { // Otherwise, during normal situations let regular limit.
_THRminf = aparm.throttle_min * 0.01f;
}
// Raise min to force max throttle for TKOFF_THR_MAX_T after a takeoff.
if (_flight_stage == AP_FixedWing::FlightStage::TAKEOFF) {
const uint32_t now = AP_HAL::millis();
if (_takeoff_start_ms == 0) {
_takeoff_start_ms = now;
}
const uint32_t dt = now - _takeoff_start_ms;
if (dt*0.001 < aparm.takeoff_throttle_max_t) {
_THRminf = _THRmaxf;
}
} else {
_takeoff_start_ms = 0;
}
// If we are flaring, allow the throttle to go to 0.
if (_landing.is_flaring()) {
_THRminf = 0;
}
// In any case, constrain to the external safety limits.
_THRminf = MAX(_THRminf, _THRminf_ext);

// Allow a minimum of 1% throttle range, primarily to prevent TECS numerical errors.
if (_THRmaxf < 1) {
_THRmaxf = MAX(_THRmaxf, _THRminf + 0.01f);
} else {
_THRminf = MIN(_THRminf, _THRmaxf - 0.01f);
}

// Reset the external throttle limits.
_THRminf_ext = -1.0f;
_THRmaxf_ext = 1.0f;
}
20 changes: 20 additions & 0 deletions libraries/AP_TECS/AP_TECS.h
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,14 @@ class AP_TECS {
_pitch_max_limit = pitch_limit;
}

// set minimum throttle override, [-1, -1] range
// it is applicable for one control cycle only
void set_throttle_min(const float thr_min);

// set minimum throttle override, [0, -1] range
// it is applicable for one control cycle only
void set_throttle_max(const float thr_max);

// force use of synthetic airspeed for one loop
void use_synthetic_airspeed(void) {
_use_synthetic_airspeed_once = true;
Expand Down Expand Up @@ -360,6 +368,9 @@ class AP_TECS {
// Maximum and minimum floating point throttle limits
float _THRmaxf;
float _THRminf;
// Maximum and minimum throttle safety limits, set externally, typically by servos.cpp:apply_throttle_limits()
float _THRmaxf_ext = 1.0f;
float _THRminf_ext = -1.0f;

// Maximum and minimum floating point pitch limits
float _PITCHmaxf;
Expand Down Expand Up @@ -419,6 +430,9 @@ class AP_TECS {
// need to reset on next loop
bool _need_reset;

// Checks if we reset at the beginning of takeoff.
bool _flag_have_reset_after_takeoff;

float _SKE_weighting;

AP_Int8 _use_synthetic_airspeed;
Expand Down Expand Up @@ -458,6 +472,9 @@ class AP_TECS {
// Update Demanded Throttle Non-Airspeed
void _update_throttle_without_airspeed(int16_t throttle_nudge, float pitch_trim_deg);

// Constrain throttle demand and record clipping
void constrain_throttle();

// get integral gain which is flight_stage dependent
float _get_i_gain(void);

Expand All @@ -478,4 +495,7 @@ class AP_TECS {

// current time constant
float timeConstant(void) const;

// Update the allowable throttle range.
void _update_throttle_limits();
};
2 changes: 2 additions & 0 deletions libraries/AP_Vehicle/AP_FixedWing.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,8 @@ struct AP_FixedWing {
AP_Int8 throttle_slewrate;
AP_Int8 throttle_cruise;
AP_Int8 takeoff_throttle_max;
AP_Int8 takeoff_throttle_min;
AP_Int8 takeoff_mode;
AP_Int16 airspeed_min;
AP_Int16 airspeed_max;
AP_Float airspeed_cruise;
Expand Down

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