ardupilot/ArduCopter/heli_control_acro.cpp

#include "Copter.h"

#if FRAME_CONFIG == HELI_FRAME
/*
 * Init and run calls for acro flight mode for trad heli
 */

// heli_acro_init - initialise acro controller
bool Copter::heli_acro_init(bool ignore_checks)
{
    // if heli is equipped with a flybar, then tell the attitude controller to pass through controls directly to servos
    attitude_control->use_flybar_passthrough(motors->has_flybar(), motors->supports_yaw_passthrough());

    motors->set_acro_tail(true);
    
    // set stab collective false to use full collective pitch range
    input_manager.set_use_stab_col(false);

    // always successfully enter acro
    return true;
}

// heli_acro_run - runs the acro controller
// should be called at 100hz or more
void Copter::heli_acro_run()
{
    float target_roll, target_pitch, target_yaw;
    float pilot_throttle_scaled;
    
    // Tradheli should not reset roll, pitch, yaw targets when motors are not runup, because
    // we may be in autorotation flight.  These should be reset only when transitioning from disarmed
    // to armed, because the pilot will have placed the helicopter down on the landing pad.  This is so
    // that the servos move in a realistic fashion while disarmed for operational checks.
    // Also, unlike multicopters we do not set throttle (i.e. collective pitch) to zero so the swash servos move
    
    if(!motors->armed()) {
        heli_flags.init_targets_on_arming=true;
        attitude_control->set_yaw_target_to_current_heading();
    }
    
    if(motors->armed() && heli_flags.init_targets_on_arming) {
        attitude_control->set_yaw_target_to_current_heading();
        if (motors->rotor_speed_above_critical()) {
            heli_flags.init_targets_on_arming=false;
        }
    }   

    // clear landing flag above zero throttle
    if (motors->armed() && motors->get_interlock() && motors->rotor_runup_complete() && !ap.throttle_zero) {
        set_land_complete(false);
    }

    if (!motors->has_flybar()){
        // convert the input to the desired body frame rate
        get_pilot_desired_angle_rates(channel_roll->get_control_in(), channel_pitch->get_control_in(), channel_yaw->get_control_in(), target_roll, target_pitch, target_yaw);

        if (motors->supports_yaw_passthrough()) {
            // if the tail on a flybar heli has an external gyro then
            // also use no deadzone for the yaw control and
            // pass-through the input direct to output.
            target_yaw = channel_yaw->get_control_in_zero_dz();
        }

        // run attitude controller
        attitude_control->input_rate_bf_roll_pitch_yaw(target_roll, target_pitch, target_yaw);
    }else{
        /*
          for fly-bar passthrough use control_in values with no
          deadzone. This gives true pass-through.
         */
        float roll_in = channel_roll->get_control_in_zero_dz();
        float pitch_in = channel_pitch->get_control_in_zero_dz();
        float yaw_in;
        
        if (motors->supports_yaw_passthrough()) {
            // if the tail on a flybar heli has an external gyro then
            // also use no deadzone for the yaw control and
            // pass-through the input direct to output.
            yaw_in = channel_yaw->get_control_in_zero_dz();
        } else {
            // if there is no external gyro then run the usual
            // ACRO_YAW_P gain on the input control, including
            // deadzone
            yaw_in = get_pilot_desired_yaw_rate(channel_yaw->get_control_in());
        }

        // run attitude controller
        attitude_control->passthrough_bf_roll_pitch_rate_yaw(roll_in, pitch_in, yaw_in);
    }

    // get pilot's desired throttle
    pilot_throttle_scaled = input_manager.get_pilot_desired_collective(channel_throttle->get_control_in());

    // output pilot's throttle without angle boost
    attitude_control->set_throttle_out(pilot_throttle_scaled, false, g.throttle_filt);
}

#endif  //HELI_FRAME