ardupilot/ArduSub/land_detector.cpp

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-

#include "Sub.h"
#define LAND_END_DEPTH -20 //Landed at 20cm depth

// counter to verify landings
static uint32_t land_detector_count = 0;

// run land and crash detectors
// called at MAIN_LOOP_RATE
void Sub::update_land_and_crash_detectors()
{
    // update 1hz filtered acceleration
    Vector3f accel_ef = ahrs.get_accel_ef_blended();
    accel_ef.z += GRAVITY_MSS;
    land_accel_ef_filter.apply(accel_ef, MAIN_LOOP_SECONDS);

    update_land_detector();

    crash_check();
}

// update_land_detector - checks if we have landed and updates the ap.land_complete flag
// called at MAIN_LOOP_RATE
void Sub::update_land_detector()
{
	if(barometer.num_instances() > 1 && barometer.get_altitude() > LAND_END_DEPTH && ap.throttle_zero) {
		set_land_complete(true);
	} else {
		set_land_complete(false);
	}
}

void Sub::set_land_complete(bool b)
{
    // if no change, exit immediately
    if( ap.land_complete == b )
        return;

    land_detector_count = 0;

    if(b){
        Log_Write_Event(DATA_LAND_COMPLETE);
    } else {
        Log_Write_Event(DATA_NOT_LANDED);
    }
    ap.land_complete = b;
}

// update_throttle_thr_mix - sets motors throttle_low_comp value depending upon vehicle state
//  low values favour pilot/autopilot throttle over attitude control, high values favour attitude control over throttle
//  has no effect when throttle is above hover throttle
void Sub::update_throttle_thr_mix()
{
#if FRAME_CONFIG != HELI_FRAME
    // if disarmed or landed prioritise throttle
    if(!motors.armed() || ap.land_complete) {
        motors.set_throttle_mix_min();
        return;
    }

    if (mode_has_manual_throttle(control_mode)) {
        // manual throttle
        if(channel_throttle->control_in <= 0) {
            motors.set_throttle_mix_min();
        } else {
            motors.set_throttle_mix_mid();
        }
    } else {
        // autopilot controlled throttle

        // check for aggressive flight requests - requested roll or pitch angle below 15 degrees
        const Vector3f angle_target = attitude_control.get_att_target_euler_cd();
        bool large_angle_request = (pythagorous2(angle_target.x, angle_target.y) > 1500.0f);

        // check for large external disturbance - angle error over 30 degrees
        const Vector3f angle_error = attitude_control.get_att_error_rot_vec_cd();
        bool large_angle_error = (pythagorous2(angle_error.x, angle_error.y) > 3000.0f);

        // check for large acceleration - falling or high turbulence
        Vector3f accel_ef = ahrs.get_accel_ef_blended();
        accel_ef.z += GRAVITY_MSS;
        bool accel_moving = (accel_ef.length() > 3.0f);

        // check for requested decent
        bool descent_not_demanded = pos_control.get_desired_velocity().z >= 0.0f;

        if ( large_angle_request || large_angle_error || accel_moving || descent_not_demanded) {
            motors.set_throttle_mix_max();
        } else {
            motors.set_throttle_mix_min();
        }
    }
#endif
}