ardupilot/ArduCopter/control_ofloiter.pde

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

/*
 * control_ofloiter.pde - init and run calls for of_loiter (optical flow loiter) flight mode
 */

#if OPTFLOW == ENABLED

// ofloiter_init - initialise ofloiter controller
static bool ofloiter_init(bool ignore_checks)
{
    if (g.optflow_enabled || ignore_checks) {

        // initialize vertical speed and acceleration
        pos_control.set_speed_z(-g.pilot_velocity_z_max, g.pilot_velocity_z_max);
        pos_control.set_accel_z(g.pilot_accel_z);

        // initialise altitude target to stopping point
        pos_control.set_target_to_stopping_point_z();

        return true;
    }else{
        return false;
    }
}

// ofloiter_run - runs the optical flow loiter controller
// should be called at 100hz or more
static void ofloiter_run()
{
    int16_t target_roll, target_pitch;
    float target_yaw_rate = 0;
    float target_climb_rate = 0;

    // if not auto armed set throttle to zero and exit immediately
    if(!ap.auto_armed) {
        attitude_control.relax_bf_rate_controller();
        attitude_control.set_yaw_target_to_current_heading();
        attitude_control.set_throttle_out(0, false);
        pos_control.set_alt_target_to_current_alt();
        reset_optflow_I();
        return;
    }

    // process pilot inputs
    if (!failsafe.radio) {
        // apply SIMPLE mode transform to pilot inputs
        update_simple_mode();

        // convert pilot input to lean angles
        get_pilot_desired_lean_angles(g.rc_1.control_in, g.rc_2.control_in, target_roll, target_pitch);

        // get pilot's desired yaw rate
        target_yaw_rate = get_pilot_desired_yaw_rate(g.rc_4.control_in);

        // get pilot desired climb rate
        target_climb_rate = get_pilot_desired_climb_rate(g.rc_3.control_in);

        // check for pilot requested take-off
        if (ap.land_complete && target_climb_rate > 0) {
            // indicate we are taking off
            set_land_complete(false);
            // clear i term when we're taking off
            set_throttle_takeoff();
        }
    }

    // when landed reset targets and output zero throttle
    if (ap.land_complete) {
        attitude_control.relax_bf_rate_controller();
        attitude_control.set_yaw_target_to_current_heading();
        // move throttle to between minimum and non-takeoff-throttle to keep us on the ground
        attitude_control.set_throttle_out(get_throttle_pre_takeoff(g.rc_3.control_in), false);
        pos_control.set_alt_target_to_current_alt();
        reset_optflow_I();
    }else{
        // mix in user control with optical flow
        target_roll = get_of_roll(target_roll);
        target_pitch = get_of_pitch(target_pitch);

        // call attitude controller
        attitude_control.angle_ef_roll_pitch_rate_ef_yaw_smooth(target_roll, target_pitch, target_yaw_rate, get_smoothing_gain());

        // run altitude controller
        if (sonar_alt_health >= SONAR_ALT_HEALTH_MAX) {
            // if sonar is ok, use surface tracking
            target_climb_rate = get_throttle_surface_tracking(target_climb_rate, pos_control.get_alt_target(), G_Dt);
        }

        // update altitude target and call position controller
        pos_control.set_alt_target_from_climb_rate(target_climb_rate, G_Dt);
        pos_control.update_z_controller();
    }
}


// calculate modified roll/pitch depending upon optical flow calculated position
static int32_t get_of_roll(int32_t input_roll)
{
    static float tot_x_cm = 0;      // total distance from target
    static uint32_t last_of_roll_update = 0;
    int32_t new_roll = 0;
    int32_t p,i,d;

    // check if new optflow data available
    if( optflow.last_update != last_of_roll_update) {
        last_of_roll_update = optflow.last_update;

        // add new distance moved
        tot_x_cm += optflow.x_cm;

        // only stop roll if caller isn't modifying roll
        if( input_roll == 0 && current_loc.alt < 1500) {
            p = g.pid_optflow_roll.get_p(-tot_x_cm);
            i = g.pid_optflow_roll.get_i(-tot_x_cm,1.0f);              // we could use the last update time to calculate the time change
            d = g.pid_optflow_roll.get_d(-tot_x_cm,1.0f);
            new_roll = p+i+d;
        }else{
            g.pid_optflow_roll.reset_I();
            tot_x_cm = 0;
            p = 0;              // for logging
            i = 0;
            d = 0;
        }
        // limit amount of change and maximum angle
        of_roll = constrain_int32(new_roll, (of_roll-20), (of_roll+20));
    }

    // limit max angle
    of_roll = constrain_int32(of_roll, -1000, 1000);

    return input_roll+of_roll;
}

static int32_t get_of_pitch(int32_t input_pitch)
{
    static float tot_y_cm = 0;  // total distance from target
    static uint32_t last_of_pitch_update = 0;
    int32_t new_pitch = 0;
    int32_t p,i,d;

    // check if new optflow data available
    if( optflow.last_update != last_of_pitch_update ) {
        last_of_pitch_update = optflow.last_update;

        // add new distance moved
        tot_y_cm += optflow.y_cm;

        // only stop roll if caller isn't modifying pitch
        if( input_pitch == 0 && current_loc.alt < 1500 ) {
            p = g.pid_optflow_pitch.get_p(tot_y_cm);
            i = g.pid_optflow_pitch.get_i(tot_y_cm, 1.0f);              // we could use the last update time to calculate the time change
            d = g.pid_optflow_pitch.get_d(tot_y_cm, 1.0f);
            new_pitch = p + i + d;
        }else{
            tot_y_cm = 0;
            g.pid_optflow_pitch.reset_I();
            p = 0;              // for logging
            i = 0;
            d = 0;
        }

        // limit amount of change
        of_pitch = constrain_int32(new_pitch, (of_pitch-20), (of_pitch+20));
    }

    // limit max angle
    of_pitch = constrain_int32(of_pitch, -1000, 1000);

    return input_pitch+of_pitch;
}

// reset_optflow_I - reset optflow position hold I terms
static void reset_optflow_I(void)
{
    g.pid_optflow_roll.reset_I();
    g.pid_optflow_pitch.reset_I();
    of_roll = 0;
    of_pitch = 0;
}

#endif // OPTFLOW == ENABLED