ardupilot/ArduCopter/heli.cpp

#include "Copter.h"

// Traditional helicopter variables and functions

#if FRAME_CONFIG == HELI_FRAME

#ifndef HELI_DYNAMIC_FLIGHT_SPEED_MIN
#define HELI_DYNAMIC_FLIGHT_SPEED_MIN      250     // we are in "dynamic flight" when the speed is over 2.5m/s for 2 seconds
#endif

// counter to control dynamic flight profile
static int8_t heli_dynamic_flight_counter;

// heli_init - perform any special initialisation required for the tradheli
void Copter::heli_init()
{
    // pre-load stab col values as mode is initialized as Stabilize, but stabilize_init() function is not run on start-up.
    input_manager.set_use_stab_col(true);
    input_manager.set_stab_col_ramp(1.0);
}

// heli_check_dynamic_flight - updates the dynamic_flight flag based on our horizontal velocity
// should be called at 50hz
void Copter::check_dynamic_flight(void)
{
    if (motors->get_spool_state() != AP_Motors::SpoolState::THROTTLE_UNLIMITED ||
        flightmode->is_landing()) {
        heli_dynamic_flight_counter = 0;
        heli_flags.dynamic_flight = false;
        return;
    }

    bool moving = false;

    // with GPS lock use inertial nav to determine if we are moving
    if (position_ok()) {
        // get horizontal speed
        const float speed = inertial_nav.get_speed_xy_cms();
        moving = (speed >= HELI_DYNAMIC_FLIGHT_SPEED_MIN);
    } else {
        // with no GPS lock base it on throttle and forward lean angle
        moving = (motors->get_throttle() > 0.8f || ahrs.pitch_sensor < -1500);
    }

#if AP_RANGEFINDER_ENABLED
    if (!moving && rangefinder_state.enabled && rangefinder.status_orient(ROTATION_PITCH_270) == RangeFinder::Status::Good) {
        // when we are more than 2m from the ground with good
        // rangefinder lock consider it to be dynamic flight
        moving = (rangefinder.distance_cm_orient(ROTATION_PITCH_270) > 200);
    }
#endif

    if (moving) {
        // if moving for 2 seconds, set the dynamic flight flag
        if (!heli_flags.dynamic_flight) {
            heli_dynamic_flight_counter++;
            if (heli_dynamic_flight_counter >= 100) {
                heli_flags.dynamic_flight = true;
                heli_dynamic_flight_counter = 100;
            }
        }
    } else {
        // if not moving for 2 seconds, clear the dynamic flight flag
        if (heli_flags.dynamic_flight) {
            if (heli_dynamic_flight_counter > 0) {
                heli_dynamic_flight_counter--;
            } else {
                heli_flags.dynamic_flight = false;
            }
        }
    }
}

// update_heli_control_dynamics - pushes several important factors up into AP_MotorsHeli.
// should be run between the rate controller and the servo updates.
void Copter::update_heli_control_dynamics(void)
{

    if (!motors->using_leaky_integrator()) {
        //turn off leaky_I
        attitude_control->use_leaky_i(false);
        if (ap.land_complete || ap.land_complete_maybe) {
            motors->set_land_complete(true);
        } else {
            motors->set_land_complete(false);
        }
    } else {
        // Use Leaky_I if we are not moving fast
        attitude_control->use_leaky_i(!heli_flags.dynamic_flight);
        motors->set_land_complete(false);
    }

    if (ap.land_complete || (is_zero(motors->get_desired_rotor_speed()))) {
        // if we are landed or there is no rotor power demanded, decrement slew scalar
        hover_roll_trim_scalar_slew--;
    } else {
        // if we are not landed and motor power is demanded, increment slew scalar
        hover_roll_trim_scalar_slew++;
    }
    hover_roll_trim_scalar_slew = constrain_int16(hover_roll_trim_scalar_slew, 0, scheduler.get_loop_rate_hz());

    // set hover roll trim scalar, will ramp from 0 to 1 over 1 second after we think helicopter has taken off
    attitude_control->set_hover_roll_trim_scalar((float) hover_roll_trim_scalar_slew/(float) scheduler.get_loop_rate_hz());
}

bool Copter::should_use_landing_swash() const
{
    if (flightmode->has_manual_throttle() ||
        flightmode->mode_number() == Mode::Number::DRIFT ||
        attitude_control->get_inverted_flight()) {
        // manual modes or modes using inverted flight uses full swash range
        return false;
    }
    if (flightmode->is_landing()) {
        // landing with non-manual throttle mode always uses limit swash range
        return true;
    }
    if (ap.land_complete) {
        // when landed in non-manual throttle mode limit swash range
        return true;
    }
    if (!ap.auto_armed) {
        // when waiting to takeoff in non-manual throttle mode limit swash range
        return true;
    }
    if (!heli_flags.dynamic_flight) {
        // Just in case we are unsure of being in non-manual throttle
        // mode, limit swash range in low speed and hovering flight.
        // This will catch any non-manual throttle mode attempting a
        // landing and driving the collective too low before the land
        // complete flag is set.
        return true;
    }
    return false;
}

// heli_update_landing_swash - sets swash plate flag so higher minimum is used when landed or landing
// should be called soon after update_land_detector in main code
void Copter::heli_update_landing_swash()
{
    motors->set_collective_for_landing(should_use_landing_swash());
    update_collective_low_flag(channel_throttle->get_control_in());
}

// convert motor interlock switch's position to desired rotor speed expressed as a value from 0 to 1
// returns zero if motor interlock auxiliary switch hasn't been defined
float Copter::get_pilot_desired_rotor_speed() const
{
    RC_Channel *rc_ptr = rc().find_channel_for_option(RC_Channel::AUX_FUNC::MOTOR_INTERLOCK);
    if (rc_ptr != nullptr) {
        rc_ptr->set_range(1000);
        return (float)rc_ptr->get_control_in() * 0.001f;
    }
    return 0.0f;
}

// heli_update_rotor_speed_targets - reads pilot input and passes new rotor speed targets to heli motors object
void Copter::heli_update_rotor_speed_targets()
{
    // get rotor control method
    uint8_t rsc_control_mode = motors->get_rsc_mode();

    switch (rsc_control_mode) {
    case ROTOR_CONTROL_MODE_PASSTHROUGH:
        // pass through pilot desired rotor speed from the RC
        if (get_pilot_desired_rotor_speed() > 0.01) {
            ap.motor_interlock_switch = true;
            motors->set_desired_rotor_speed(get_pilot_desired_rotor_speed());
        } else {
            ap.motor_interlock_switch = false;
            motors->set_desired_rotor_speed(0.0f);
        }
        break;
    case ROTOR_CONTROL_MODE_SETPOINT:
    case ROTOR_CONTROL_MODE_THROTTLECURVE:
    case ROTOR_CONTROL_MODE_AUTOTHROTTLE:
        if (motors->get_interlock()) {
            motors->set_desired_rotor_speed(motors->get_rsc_setpoint());
        } else {
            motors->set_desired_rotor_speed(0.0f);
        }
        break;
    }

}


// heli_update_autorotation - determines if aircraft is in autorotation and sets motors flag and switches
// to autorotation flight mode if manual collective is not being used.
void Copter::heli_update_autorotation()
{
    bool in_autorotation_mode = false;
#if MODE_AUTOROTATE_ENABLED
    in_autorotation_mode = flightmode == &mode_autorotate;
#endif

    // If we have landed then we do not want to be in autorotation and we do not want to via the bailout state
    if (ap.land_complete || ap.land_complete_maybe) {
        motors->force_deactivate_autorotation();
        return;
    }

    // if we got this far we are flying, check for conditions to set autorotation state
    if (!motors->get_interlock() && (flightmode->has_manual_throttle() || in_autorotation_mode)) {
        // set state in motors to facilitate manual and assisted autorotations
        motors->set_autorotation_active(true);
    } else {
        // deactivate the autorotation state via the bailout case
        motors->set_autorotation_active(false);
    }
}

// update collective low flag.  Use a debounce time of 400 milliseconds.
void Copter::update_collective_low_flag(int16_t throttle_control)
{
    static uint32_t last_nonzero_collective_ms = 0;
    uint32_t tnow_ms = millis();

    if (throttle_control > 0) {
        last_nonzero_collective_ms = tnow_ms;
        heli_flags.coll_stk_low = false;
    } else if (tnow_ms - last_nonzero_collective_ms > 400) {
        heli_flags.coll_stk_low = true;
    }
}

#endif  // FRAME_CONFIG == HELI_FRAME