ardupilot/ArduCopter/Attitude.cpp

#include "Copter.h"

/*************************************************************
 *  Attitude Rate controllers and timing
 ****************************************************************/

/*
  update rate controller when run from main thread (normal operation)
*/
void Copter::run_rate_controller_main()
{
    // set attitude and position controller loop time
    const float last_loop_time_s = AP::scheduler().get_last_loop_time_s();
    pos_control->set_dt_s(last_loop_time_s);
    attitude_control->set_dt_s(last_loop_time_s);

    if (!using_rate_thread) {
        motors->set_dt_s(last_loop_time_s);
        // only run the rate controller if we are not using the rate thread
        attitude_control->rate_controller_run();
    }
    // reset sysid and other temporary inputs
    attitude_control->rate_controller_target_reset();
}

/*************************************************************
 *  throttle control
 ****************************************************************/

// update estimated throttle required to hover (if necessary)
//  called at 100hz
void Copter::update_throttle_hover()
{
    // if not armed or landed or on standby then exit
    if (!motors->armed() || ap.land_complete || standby_active) {
        return;
    }

    // do not update in manual throttle modes or Drift
    if (flightmode->has_manual_throttle() || (copter.flightmode->mode_number() == Mode::Number::DRIFT)) {
        return;
    }

    // do not update while climbing or descending
    if (!is_zero(pos_control->get_vel_desired_U_ms())) {
        return;
    }

    // do not update if no vertical velocity estimate
    float vel_d_ms;
    if (!AP::ahrs().get_velocity_D(vel_d_ms, vibration_check.high_vibes)) {
        return;
    }

    // get throttle output
    float throttle = motors->get_throttle();

    // calc average throttle if we are in a level hover.  accounts for heli hover roll trim
    if ((throttle > 0.0f) && (fabsf(vel_d_ms) < 0.6) &&
        (fabsf(ahrs.get_roll_rad() - attitude_control->get_roll_trim_rad()) < radians(5)) && (fabsf(ahrs.get_pitch_rad()) < radians(5))) {
        // Can we set the time constant automatically
        motors->update_throttle_hover(0.01f);
#if HAL_GYROFFT_ENABLED
        gyro_fft.update_freq_hover(0.01f, motors->get_throttle_out());
#endif
    }
}

// get_pilot_desired_climb_rate_ms - transform pilot's throttle input to climb rate in m/s
// without any deadzone at the bottom.
// The max climb and descent rates are adjusted for any climb/descent rate currently being
// commanded by surface tracking, so full stick deflection always yields net vehicle climb
// or descent at PILOT_SPD_UP  / PILOT_SPD_DN  (see get_pilot_speed_up_adjusted_ms()).
float Copter::get_pilot_desired_climb_rate_ms()
{
    // throttle failsafe check
    if (!rc().has_valid_input()) {
        return 0.0f;
    }

    float throttle_control = copter.channel_throttle->get_control_in();

#if TOY_MODE_ENABLED
    if (g2.toy_mode.enabled()) {
        // allow throttle to be reduced after throttle arming and for
        // slower descent close to the ground
        g2.toy_mode.throttle_adjust(throttle_control);
    }
#endif

    // ensure a reasonable throttle value
    throttle_control = constrain_float(throttle_control, 0.0f, 1000.0f);

    // ensure a reasonable deadzone
    g.throttle_deadzone.set(constrain_int16(g.throttle_deadzone, 0, 400));

    float desired_rate_ms = 0.0f;
    const float mid_stick = get_throttle_mid();
    const float deadband_top = mid_stick + g.throttle_deadzone;
    const float deadband_bottom = mid_stick - g.throttle_deadzone;

    // check throttle is above, below or in the deadband
    if (throttle_control < deadband_bottom) {
        // below the deadband
        desired_rate_ms = get_pilot_speed_dn_adjusted_ms() * (throttle_control - deadband_bottom) / deadband_bottom;
    } else if (throttle_control > deadband_top) {
        // above the deadband
        desired_rate_ms = get_pilot_speed_up_adjusted_ms() * (throttle_control - deadband_top) / (1000.0 - deadband_top);
    } else {
        // must be in the deadband
        desired_rate_ms = 0.0f;
    }

    return desired_rate_ms;
}

// get_non_takeoff_throttle - a throttle somewhere between min and mid throttle which should not lead to a takeoff
float Copter::get_non_takeoff_throttle()
{
    return MAX(0,motors->get_throttle_hover() / 2.0);
}

// set_accel_throttle_I_from_pilot_throttle - smoothes transition from pilot controlled throttle to autopilot throttle
void Copter::set_accel_throttle_I_from_pilot_throttle()
{
    // get last throttle input sent to attitude controller
    float pilot_throttle = constrain_float(attitude_control->get_throttle_in(), 0.0, 1.0);
    // shift difference between pilot's throttle and hover throttle into accelerometer I
    pos_control->D_get_accel_pid().set_integrator(-(pilot_throttle - motors->get_throttle_hover()));
}

// It will return the PILOT_SPD_DN value if non zero, otherwise if zero it returns the PILOT_SPD_UP value.
float Copter::get_pilot_speed_dn_ms() const
{
    if (is_zero(g2.pilot_speed_dn_ms)) {
        return fabsf(g2.pilot_speed_up_ms);
    } else {
        return fabsf(g2.pilot_speed_dn_ms);
    }
}

// Returns the maximum pilot climb rate (m/s) adjusted for the climb/descent rate currently
// being commanded by surface tracking, to always result in at least PILOT_SPD_UP on full up stick.
float Copter::get_pilot_speed_up_adjusted_ms() const
{
    // terrain velocity in Up-positive frame (m/s)
    const float terrain_climb_ms = -pos_control->get_vel_terrain_D_ms();
    // floored at zero to prevent sign flip if terrain velocity exceeds PILOT_SPD_UP
    return MAX(0.0f, g2.pilot_speed_up_ms - terrain_climb_ms);
}

// Returns the maximum pilot descent rate (m/s, positive magnitude) adjusted for the
// climb/descent rate currently being commanded by surface tracking, to always result in
// at least PILOT_SPD_DN on full down stick.
float Copter::get_pilot_speed_dn_adjusted_ms() const
{
    // terrain velocity in Up-positive frame (m/s)
    const float terrain_climb_ms = -pos_control->get_vel_terrain_D_ms();
    // floored at zero to prevent sign flip if terrain velocity exceeds PILOT_SPD_DN
    return MAX(0.0f, get_pilot_speed_dn_ms() + terrain_climb_ms);
}