ardupilot/libraries/AP_TECS/AP_TECS.h

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C++

/// @file AP_TECS.h
/// @brief Combined Total Energy Speed & Height Control. This is a instance of an
/*
* Written by Paul Riseborough 2013 to provide:
* - Combined control of speed and height using throttle to control
* total energy and pitch angle to control exchange of energy between
* potential and kinetic.
* Selectable speed or height priority modes when calculating pitch angle
* - Fallback mode when no airspeed measurement is available that
* sets throttle based on height rate demand and switches pitch angle control to
* height priority
* - Underspeed protection that demands maximum throttle switches pitch angle control
* to speed priority mode
* - Relative ease of tuning through use of intuitive time constant, trim rate and damping parameters and the use
* of easy to measure aircraft performance data
*/
#pragma once
#include <AP_Math/AP_Math.h>
#include <AP_AHRS/AP_AHRS.h>
#include <AP_Param/AP_Param.h>
#include <AP_Vehicle/AP_Vehicle.h>
class AP_Landing;
class AP_TECS {
public:
AP_TECS(AP_AHRS &ahrs, const AP_Vehicle::FixedWing &parms, const AP_Landing &landing)
: _ahrs(ahrs)
, aparm(parms)
, _landing(landing)
{
AP_Param::setup_object_defaults(this, var_info);
}
/* Do not allow copies */
AP_TECS(const AP_TECS &other) = delete;
AP_TECS &operator=(const AP_TECS&) = delete;
// Update of the estimated height and height rate internal state
// Update of the inertial speed rate internal state
// Should be called at 50Hz or greater
void update_50hz(void);
// Update the control loop calculations
void update_pitch_throttle(int32_t hgt_dem_cm,
int32_t EAS_dem_cm,
enum AP_Vehicle::FixedWing::FlightStage flight_stage,
float distance_beyond_land_wp,
int32_t ptchMinCO_cd,
int16_t throttle_nudge,
float hgt_afe,
float load_factor);
// demanded throttle in percentage
// should return -100 to 100, usually positive unless reverse thrust is enabled via _THRminf < 0
float get_throttle_demand(void) {
return _throttle_dem * 100.0f;
}
// demanded pitch angle in centi-degrees
// should return between -9000 to +9000
int32_t get_pitch_demand(void) {
return int32_t(_pitch_dem * 5729.5781f);
}
// Rate of change of velocity along X body axis in m/s^2
float get_VXdot(void) {
return _vel_dot;
}
// return current target airspeed
float get_target_airspeed(void) const {
return _TAS_dem_adj / _ahrs.get_EAS2TAS();
}
// return maximum climb rate
float get_max_climbrate(void) const {
return _maxClimbRate;
}
// return maximum sink rate (+ve number down)
float get_max_sinkrate(void) const {
return _maxSinkRate;
}
// added to let SoaringContoller reset pitch integrator to zero
void reset_pitch_I(void) {
_integSEB_state = 0.0f;
}
// return landing sink rate
float get_land_sinkrate(void) const {
return _land_sink;
}
// return landing airspeed
float get_land_airspeed(void) const {
return _landAirspeed;
}
// return height rate demand, in m/s
float get_height_rate_demand(void) const {
return _hgt_rate_dem;
}
// set path_proportion
void set_path_proportion(float path_proportion) {
_path_proportion = constrain_float(path_proportion, 0.0f, 1.0f);
}
// set soaring flag
void set_gliding_requested_flag(bool gliding_requested) {
_flags.gliding_requested = gliding_requested;
}
// set propulsion failed flag
void set_propulsion_failed_flag(bool propulsion_failed) {
_flags.propulsion_failed = propulsion_failed;
}
// set pitch max limit in degrees
void set_pitch_max_limit(int8_t pitch_limit) {
_pitch_max_limit = pitch_limit;
}
// force use of synthetic airspeed for one loop
void use_synthetic_airspeed(void) {
_use_synthetic_airspeed_once = true;
}
// reset on next loop
void reset(void) {
_need_reset = true;
}
// this supports the TECS_* user settable parameters
static const struct AP_Param::GroupInfo var_info[];
private:
// Last time update_50Hz was called
uint64_t _update_50hz_last_usec;
// Last time update_speed was called
uint64_t _update_speed_last_usec;
// Last time update_pitch_throttle was called
uint64_t _update_pitch_throttle_last_usec;
// reference to the AHRS object
AP_AHRS &_ahrs;
const AP_Vehicle::FixedWing &aparm;
// reference to const AP_Landing to access it's params
const AP_Landing &_landing;
// TECS tuning parameters
AP_Float _hgtCompFiltOmega;
AP_Float _spdCompFiltOmega;
AP_Float _maxClimbRate;
AP_Float _minSinkRate;
AP_Float _maxSinkRate;
AP_Float _timeConst;
AP_Float _landTimeConst;
AP_Float _ptchDamp;
AP_Float _land_pitch_damp;
AP_Float _landDamp;
AP_Float _thrDamp;
AP_Float _land_throttle_damp;
AP_Float _integGain;
AP_Float _integGain_takeoff;
AP_Float _integGain_land;
AP_Float _vertAccLim;
AP_Float _rollComp;
AP_Float _spdWeight;
AP_Float _spdWeightLand;
AP_Float _landThrottle;
AP_Float _landAirspeed;
AP_Float _land_sink;
AP_Float _land_sink_rate_change;
AP_Int8 _pitch_max;
AP_Int8 _pitch_min;
AP_Int8 _land_pitch_max;
AP_Float _maxSinkRate_approach;
AP_Int32 _options;
enum {
OPTION_GLIDER_ONLY=(1<<0),
};
AP_Float _pitch_ff_v0;
AP_Float _pitch_ff_k;
// temporary _pitch_max_limit. Cleared on each loop. Clear when >= 90
int8_t _pitch_max_limit = 90;
// current height estimate (above field elevation)
float _height;
// throttle demand in the range from -1.0 to 1.0, usually positive unless reverse thrust is enabled via _THRminf < 0
float _throttle_dem;
// pitch angle demand in radians
float _pitch_dem;
// estimated climb rate (m/s)
float _climb_rate;
/*
a filter to estimate climb rate if we don't have it from the EKF
*/
struct {
// height filter second derivative
float dd_height;
// height integration
float height;
} _height_filter;
// Integrator state 4 - airspeed filter first derivative
float _integDTAS_state;
// Integrator state 5 - true airspeed
float _TAS_state;
// Integrator state 6 - throttle integrator
float _integTHR_state;
// Integrator state 6 - pitch integrator
float _integSEB_state;
// throttle demand rate limiter state
float _last_throttle_dem;
// pitch demand rate limiter state
float _last_pitch_dem;
// Rate of change of speed along X axis
float _vel_dot;
// Equivalent airspeed
float _EAS;
// True airspeed limits
float _TASmax;
float _TASmin;
// Current true airspeed demand
float _TAS_dem;
// Equivalent airspeed demand
float _EAS_dem;
// height demands
float _hgt_dem;
float _hgt_dem_in_old;
float _hgt_dem_adj;
float _hgt_dem_adj_last;
float _hgt_rate_dem;
float _hgt_dem_prev;
float _land_hgt_dem;
// Speed demand after application of rate limiting
// This is the demand tracked by the TECS control loops
float _TAS_dem_adj;
// Speed rate demand after application of rate limiting
// This is the demand tracked by the TECS control loops
float _TAS_rate_dem;
// Total energy rate filter state
float _STEdotErrLast;
struct flags {
// Underspeed condition
bool underspeed:1;
// Bad descent condition caused by unachievable airspeed demand
bool badDescent:1;
// true when plane is in auto mode and executing a land mission item
bool is_doing_auto_land:1;
// true when we have reached target speed in takeoff
bool reached_speed_takeoff:1;
// true if the soaring feature has requested gliding flight
bool gliding_requested:1;
// true when we are in gliding flight, in one of three situations;
// - THR_MAX=0
// - gliding has been requested e.g. by soaring feature
// - engine failure detected (detection not implemented currently)
bool is_gliding:1;
// true if a propulsion failure is detected.
bool propulsion_failed:1;
};
union {
struct flags _flags;
uint8_t _flags_byte;
};
// time when underspeed started
uint32_t _underspeed_start_ms;
// auto mode flightstage
enum AP_Vehicle::FixedWing::FlightStage _flight_stage;
// pitch demand before limiting
float _pitch_dem_unc;
// Maximum and minimum specific total energy rate limits
float _STEdot_max;
float _STEdot_min;
// Maximum and minimum floating point throttle limits
float _THRmaxf;
float _THRminf;
// Maximum and minimum floating point pitch limits
float _PITCHmaxf;
float _PITCHminf;
// 1 if throttle is clipping at max value, -1 if clipping at min value, 0 otherwise
enum class ThrClipStatus : int8_t {
MIN = -1,
NONE = 0,
MAX = 1,
};
ThrClipStatus _thr_clip_status;
// Specific energy quantities
float _SPE_dem;
float _SKE_dem;
float _SPEdot_dem;
float _SKEdot_dem;
float _SPE_est;
float _SKE_est;
float _SPEdot;
float _SKEdot;
// Specific energy error quantities
float _STE_error;
// Time since last update of main TECS loop (seconds)
float _DT;
// counter for demanded sink rate on land final
uint8_t _flare_counter;
// slew height demand lag filter value when transition to land
float hgt_dem_lag_filter_slew;
// percent traveled along the previous and next waypoints
float _path_proportion;
float _distance_beyond_land_wp;
float _land_pitch_min = -90;
// need to reset on next loop
bool _need_reset;
// internal variables to be logged
struct {
float SKE_weighting;
float SPE_error;
float SKE_error;
float SEB_delta;
} logging;
AP_Int8 _use_synthetic_airspeed;
// use synthetic airspeed for next loop
bool _use_synthetic_airspeed_once;
// Update the airspeed internal state using a second order complementary filter
void _update_speed(float load_factor);
// Update the demanded airspeed
void _update_speed_demand(void);
// Update the demanded height
void _update_height_demand(void);
// Detect an underspeed condition
void _detect_underspeed(void);
// Update Specific Energy Quantities
void _update_energies(void);
// Update Demanded Throttle
void _update_throttle_with_airspeed(void);
// Update Demanded Throttle Non-Airspeed
void _update_throttle_without_airspeed(int16_t throttle_nudge);
// get integral gain which is flight_stage dependent
float _get_i_gain(void);
// Detect Bad Descent
void _detect_bad_descent(void);
// Update Demanded Pitch Angle
void _update_pitch(void);
// Initialise states and variables
void _initialise_states(int32_t ptchMinCO_cd, float hgt_afe);
// Calculate specific total energy rate limits
void _update_STE_rate_lim(void);
// declares a 5point average filter using floats
AverageFilterFloat_Size5 _vdot_filter;
// current time constant
float timeConstant(void) const;
};