ardupilot/libraries/AC_AttitudeControl/AC_AttitudeControl_Sub.cpp

#include "AC_AttitudeControl_Sub.h"
#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>

// table of user settable parameters
const AP_Param::GroupInfo AC_AttitudeControl_Sub::var_info[] = {
    // parameters from parent vehicle
    AP_NESTEDGROUPINFO(AC_AttitudeControl, 0),

    // @Param: RAT_RLL_P
    // @DisplayName: Roll axis rate controller P gain
    // @Description: Roll axis rate controller P gain.  Corrects in proportion to the difference between the desired roll rate vs actual roll rate
    // @Range: 0.0 0.30
    // @Increment: 0.005
    // @User: Standard

    // @Param: RAT_RLL_I
    // @DisplayName: Roll axis rate controller I gain
    // @Description: Roll axis rate controller I gain.  Corrects long-term difference in desired roll rate vs actual roll rate
    // @Range: 0.0 0.5
    // @Increment: 0.01
    // @User: Standard

    // @Param: RAT_RLL_IMAX
    // @DisplayName: Roll axis rate controller I gain maximum
    // @Description: Roll axis rate controller I gain maximum.  Constrains the maximum that the I term will output
    // @Range: 0 1
    // @Increment: 0.01
    // @User: Standard

    // @Param: RAT_RLL_D
    // @DisplayName: Roll axis rate controller D gain
    // @Description: Roll axis rate controller D gain.  Compensates for short-term change in desired roll rate vs actual roll rate
    // @Range: 0.0 0.02
    // @Increment: 0.001
    // @User: Standard

    // @Param: RAT_RLL_FF
    // @DisplayName: Roll axis rate controller feed forward
    // @Description: Roll axis rate controller feed forward
    // @Range: 0 0.5
    // @Increment: 0.001
    // @User: Standard

    // @Param: RAT_RLL_FLTT
    // @DisplayName: Roll axis rate controller input frequency in Hz
    // @Description: Roll axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_RLL_FLTE
    // @DisplayName: Roll axis rate controller input frequency in Hz
    // @Description: Roll axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_RLL_FLTD
    // @DisplayName: Roll axis rate controller input frequency in Hz
    // @Description: Roll axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_RLL_SMAX
    // @DisplayName: Roll slew rate limit
    // @Description: Sets an upper limit on the slew rate produced by the combined P and D gains. If the amplitude of the control action produced by the rate feedback exceeds this value, then the D+P gain is reduced to respect the limit. This limits the amplitude of high frequency oscillations caused by an excessive gain. The limit should be set to no more than 25% of the actuators maximum slew rate to allow for load effects. Note: The gain will not be reduced to less than 10% of the nominal value. A value of zero will disable this feature.
    // @Range: 0 200
    // @Increment: 0.5
    // @User: Advanced

    AP_SUBGROUPINFO(_pid_rate_roll, "RAT_RLL_", 1, AC_AttitudeControl_Sub, AC_PID),

    // @Param: RAT_PIT_P
    // @DisplayName: Pitch axis rate controller P gain
    // @Description: Pitch axis rate controller P gain.  Corrects in proportion to the difference between the desired pitch rate vs actual pitch rate
    // @Range: 0.0 0.30
    // @Increment: 0.005
    // @User: Standard

    // @Param: RAT_PIT_I
    // @DisplayName: Pitch axis rate controller I gain
    // @Description: Pitch axis rate controller I gain.  Corrects long-term difference in desired pitch rate vs actual pitch rate
    // @Range: 0.0 0.5
    // @Increment: 0.01
    // @User: Standard

    // @Param: RAT_PIT_IMAX
    // @DisplayName: Pitch axis rate controller I gain maximum
    // @Description: Pitch axis rate controller I gain maximum.  Constrains the maximum that the I term will output
    // @Range: 0 1
    // @Increment: 0.01
    // @User: Standard

    // @Param: RAT_PIT_D
    // @DisplayName: Pitch axis rate controller D gain
    // @Description: Pitch axis rate controller D gain.  Compensates for short-term change in desired pitch rate vs actual pitch rate
    // @Range: 0.0 0.02
    // @Increment: 0.001
    // @User: Standard

    // @Param: RAT_PIT_FF
    // @DisplayName: Pitch axis rate controller feed forward
    // @Description: Pitch axis rate controller feed forward
    // @Range: 0 0.5
    // @Increment: 0.001
    // @User: Standard

    // @Param: RAT_PIT_FLTT
    // @DisplayName: Pitch axis rate controller input frequency in Hz
    // @Description: Pitch axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_PIT_FLTE
    // @DisplayName: Pitch axis rate controller input frequency in Hz
    // @Description: Pitch axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_PIT_FLTD
    // @DisplayName: Pitch axis rate controller input frequency in Hz
    // @Description: Pitch axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_PIT_SMAX
    // @DisplayName: Pitch slew rate limit
    // @Description: Sets an upper limit on the slew rate produced by the combined P and D gains. If the amplitude of the control action produced by the rate feedback exceeds this value, then the D+P gain is reduced to respect the limit. This limits the amplitude of high frequency oscillations caused by an excessive gain. The limit should be set to no more than 25% of the actuators maximum slew rate to allow for load effects. Note: The gain will not be reduced to less than 10% of the nominal value. A value of zero will disable this feature.
    // @Range: 0 200
    // @Increment: 0.5
    // @User: Advanced

    AP_SUBGROUPINFO(_pid_rate_pitch, "RAT_PIT_", 2, AC_AttitudeControl_Sub, AC_PID),

    // @Param: RAT_YAW_P
    // @DisplayName: Yaw axis rate controller P gain
    // @Description: Yaw axis rate controller P gain.  Corrects in proportion to the difference between the desired yaw rate vs actual yaw rate
    // @Range: 0.0 0.50
    // @Increment: 0.005
    // @User: Standard

    // @Param: RAT_YAW_I
    // @DisplayName: Yaw axis rate controller I gain
    // @Description: Yaw axis rate controller I gain.  Corrects long-term difference in desired yaw rate vs actual yaw rate
    // @Range: 0.0 0.05
    // @Increment: 0.01
    // @User: Standard

    // @Param: RAT_YAW_IMAX
    // @DisplayName: Yaw axis rate controller I gain maximum
    // @Description: Yaw axis rate controller I gain maximum.  Constrains the maximum that the I term will output
    // @Range: 0 1
    // @Increment: 0.01
    // @User: Standard

    // @Param: RAT_YAW_D
    // @DisplayName: Yaw axis rate controller D gain
    // @Description: Yaw axis rate controller D gain.  Compensates for short-term change in desired yaw rate vs actual yaw rate
    // @Range: 0.000 0.02
    // @Increment: 0.001
    // @User: Standard

    // @Param: RAT_YAW_FF
    // @DisplayName: Yaw axis rate controller feed forward
    // @Description: Yaw axis rate controller feed forward
    // @Range: 0 0.5
    // @Increment: 0.001
    // @User: Standard

    // @Param: RAT_YAW_FLTT
    // @DisplayName: Yaw axis rate controller input frequency in Hz
    // @Description: Yaw axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_YAW_FLTE
    // @DisplayName: Yaw axis rate controller input frequency in Hz
    // @Description: Yaw axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_YAW_FLTD
    // @DisplayName: Yaw axis rate controller input frequency in Hz
    // @Description: Yaw axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_YAW_SMAX
    // @DisplayName: Yaw slew rate limit
    // @Description: Sets an upper limit on the slew rate produced by the combined P and D gains. If the amplitude of the control action produced by the rate feedback exceeds this value, then the D+P gain is reduced to respect the limit. This limits the amplitude of high frequency oscillations caused by an excessive gain. The limit should be set to no more than 25% of the actuators maximum slew rate to allow for load effects. Note: The gain will not be reduced to less than 10% of the nominal value. A value of zero will disable this feature.
    // @Range: 0 200
    // @Increment: 0.5
    // @User: Advanced

    AP_SUBGROUPINFO(_pid_rate_yaw, "RAT_YAW_", 3, AC_AttitudeControl_Sub, AC_PID),

    // @Param: THR_MIX_MIN
    // @DisplayName: Throttle Mix Minimum
    // @Description: Throttle vs attitude control prioritisation used when landing (higher values mean we prioritise attitude control over throttle)
    // @Range: 0.1 0.25
    // @User: Advanced
    AP_GROUPINFO("THR_MIX_MIN", 4, AC_AttitudeControl_Sub, _thr_mix_min, AC_ATTITUDE_CONTROL_MIN_DEFAULT),

    // @Param: THR_MIX_MAX
    // @DisplayName: Throttle Mix Maximum
    // @Description: Throttle vs attitude control prioritisation used during active flight (higher values mean we prioritise attitude control over throttle)
    // @Range: 0.5 0.9
    // @User: Advanced
    AP_GROUPINFO("THR_MIX_MAX", 5, AC_AttitudeControl_Sub, _thr_mix_max, AC_ATTITUDE_CONTROL_MAX_DEFAULT),

    // @Param: THR_MIX_MAN
    // @DisplayName: Throttle Mix Manual
    // @Description: Throttle vs attitude control prioritisation used during manual flight (higher values mean we prioritise attitude control over throttle)
    // @Range: 0.5 0.9
    // @User: Advanced
    AP_GROUPINFO("THR_MIX_MAN", 6, AC_AttitudeControl_Sub, _thr_mix_man, AC_ATTITUDE_CONTROL_MAN_DEFAULT),

    // @Param: RAT_RLL_FILT
    // @DisplayName: Roll axis rate controller input frequency in Hz
    // @Description: Roll axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_PIT_FILT
    // @DisplayName: Pitch axis rate controller input frequency in Hz
    // @Description: Pitch axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    // @Param: RAT_YAW_FILT
    // @DisplayName: Yaw axis rate controller input frequency in Hz
    // @Description: Yaw axis rate controller input frequency in Hz
    // @Range: 1 100
    // @Increment: 1
    // @Units: Hz
    // @User: Standard

    AP_GROUPEND
};

AC_AttitudeControl_Sub::AC_AttitudeControl_Sub(AP_AHRS_View &ahrs, const AP_MultiCopter &aparm, AP_MotorsMulticopter& motors, float dt) :
    AC_AttitudeControl(ahrs, aparm, motors, dt),
    _motors_multi(motors),
    _pid_rate_roll(AC_ATC_SUB_RATE_RP_P, AC_ATC_SUB_RATE_RP_I, AC_ATC_SUB_RATE_RP_D, 0.0f, AC_ATC_SUB_RATE_RP_IMAX, AC_ATC_SUB_RATE_RP_FILT_HZ, 0.0f, AC_ATC_SUB_RATE_RP_FILT_HZ, dt),
    _pid_rate_pitch(AC_ATC_SUB_RATE_RP_P, AC_ATC_SUB_RATE_RP_I, AC_ATC_SUB_RATE_RP_D, 0.0f, AC_ATC_SUB_RATE_RP_IMAX, AC_ATC_SUB_RATE_RP_FILT_HZ, 0.0f, AC_ATC_SUB_RATE_RP_FILT_HZ, dt),
	_pid_rate_yaw(AC_ATC_SUB_RATE_YAW_P, AC_ATC_SUB_RATE_YAW_I, AC_ATC_SUB_RATE_YAW_D, 0.0f, AC_ATC_SUB_RATE_YAW_IMAX, AC_ATC_SUB_RATE_YAW_FILT_HZ, 0.0f, AC_ATC_SUB_RATE_YAW_FILT_HZ, dt)
{
    AP_Param::setup_object_defaults(this, var_info);

    // Sub-specific defaults for parent class
    _p_angle_roll.kP().set_default(AC_ATC_SUB_ANGLE_P);
    _p_angle_pitch.kP().set_default(AC_ATC_SUB_ANGLE_P);
    _p_angle_yaw.kP().set_default(AC_ATC_SUB_ANGLE_P);

    _accel_yaw_max.set_default(AC_ATC_SUB_ACCEL_Y_MAX);
}

// Update Alt_Hold angle maximum
void AC_AttitudeControl_Sub::update_althold_lean_angle_max(float throttle_in)
{
    // calc maximum tilt angle based on throttle
    float thr_max = _motors_multi.get_throttle_thrust_max();

    // divide by zero check
    if (is_zero(thr_max)) {
        _althold_lean_angle_max = 0.0f;
        return;
    }

    float althold_lean_angle_max = acosf(constrain_float(throttle_in/(AC_ATTITUDE_CONTROL_ANGLE_LIMIT_THROTTLE_MAX * thr_max), 0.0f, 1.0f));
    _althold_lean_angle_max = _althold_lean_angle_max + (_dt/(_dt+_angle_limit_tc))*(althold_lean_angle_max-_althold_lean_angle_max);
}

void AC_AttitudeControl_Sub::set_throttle_out(float throttle_in, bool apply_angle_boost, float filter_cutoff)
{
    _throttle_in = throttle_in;
    update_althold_lean_angle_max(throttle_in);
    _motors.set_throttle_filter_cutoff(filter_cutoff);
    _motors.set_throttle(throttle_in);
    _motors.set_throttle_avg_max(get_throttle_avg_max(MAX(throttle_in, _throttle_in)));
}

// returns a throttle including compensation for roll/pitch angle
// throttle value should be 0 ~ 1
float AC_AttitudeControl_Sub::get_throttle_boosted(float throttle_in)
{
    if (!_angle_boost_enabled) {
        _angle_boost = 0;
        return throttle_in;
    }
    // inverted_factor is 1 for tilt angles below 60 degrees
    // inverted_factor reduces from 1 to 0 for tilt angles between 60 and 90 degrees

    float cos_tilt = _ahrs.cos_pitch() * _ahrs.cos_roll();
    float inverted_factor = constrain_float(2.0f*cos_tilt, 0.0f, 1.0f);
    float boost_factor = 1.0f/constrain_float(cos_tilt, 0.5f, 1.0f);

    float throttle_out = throttle_in*inverted_factor*boost_factor;
    _angle_boost = constrain_float(throttle_out - throttle_in,-1.0f,1.0f);
    return throttle_out;
}

// returns a throttle including compensation for roll/pitch angle
// throttle value should be 0 ~ 1
float AC_AttitudeControl_Sub::get_throttle_avg_max(float throttle_in)
{
    throttle_in = constrain_float(throttle_in, 0.0f, 1.0f);
    return MAX(throttle_in, throttle_in*MAX(0.0f,1.0f-_throttle_rpy_mix)+_motors.get_throttle_hover()*_throttle_rpy_mix);
}

// update_throttle_rpy_mix - slew set_throttle_rpy_mix to requested value
void AC_AttitudeControl_Sub::update_throttle_rpy_mix()
{
    // slew _throttle_rpy_mix to _throttle_rpy_mix_desired
    if (_throttle_rpy_mix < _throttle_rpy_mix_desired) {
        // increase quickly (i.e. from 0.1 to 0.9 in 0.4 seconds)
        _throttle_rpy_mix += MIN(2.0f*_dt, _throttle_rpy_mix_desired-_throttle_rpy_mix);
    } else if (_throttle_rpy_mix > _throttle_rpy_mix_desired) {
        // reduce more slowly (from 0.9 to 0.1 in 1.6 seconds)
        _throttle_rpy_mix -= MIN(0.5f*_dt, _throttle_rpy_mix-_throttle_rpy_mix_desired);
    }
    _throttle_rpy_mix = constrain_float(_throttle_rpy_mix, 0.1f, AC_ATTITUDE_CONTROL_MAX);
}

void AC_AttitudeControl_Sub::rate_controller_run()
{
    // move throttle vs attitude mixing towards desired (called from here because this is conveniently called on every iteration)
    update_throttle_rpy_mix();

    Vector3f gyro_latest = _ahrs.get_gyro_latest();
    _motors.set_roll(get_rate_roll_pid().update_all(_ang_vel_body.x, gyro_latest.x, _motors.limit.roll));
    _motors.set_pitch(get_rate_pitch_pid().update_all(_ang_vel_body.y, gyro_latest.y, _motors.limit.pitch));
    _motors.set_yaw(get_rate_yaw_pid().update_all(_ang_vel_body.z, gyro_latest.z, _motors.limit.yaw));

    control_monitor_update();
}

// sanity check parameters.  should be called once before takeoff
void AC_AttitudeControl_Sub::parameter_sanity_check()
{
    // sanity check throttle mix parameters
    if (_thr_mix_man < 0.1f || _thr_mix_man > AC_ATTITUDE_CONTROL_MAN_LIMIT) {
        // parameter description recommends thr-mix-man be no higher than 0.9 but we allow up to 4.0
        // which can be useful for very high powered copters with very low hover throttle
        _thr_mix_man.set_and_save(constrain_float(_thr_mix_man, 0.1, AC_ATTITUDE_CONTROL_MAN_LIMIT));
    }
    if (_thr_mix_min < 0.1f || _thr_mix_min > AC_ATTITUDE_CONTROL_MIN_LIMIT) {
        _thr_mix_min.set_and_save(constrain_float(_thr_mix_min, 0.1, AC_ATTITUDE_CONTROL_MIN_LIMIT));
    }
    if (_thr_mix_max < 0.5f || _thr_mix_max > AC_ATTITUDE_CONTROL_MAX) {
        // parameter description recommends thr-mix-max be no higher than 0.9 but we allow up to 5.0
        // which can be useful for very high powered copters with very low hover throttle
        _thr_mix_max.set_and_save(constrain_float(_thr_mix_max, 0.5, AC_ATTITUDE_CONTROL_MAX));
    }
    if (_thr_mix_min > _thr_mix_max) {
        _thr_mix_min.set_and_save(AC_ATTITUDE_CONTROL_MIN_DEFAULT);
        _thr_mix_max.set_and_save(AC_ATTITUDE_CONTROL_MAX_DEFAULT);
    }
}