From 116ee348a228481512965778f444dd1c5f373939 Mon Sep 17 00:00:00 2001 From: Thomas Gubler Date: Fri, 1 Nov 2013 14:37:29 +0100 Subject: [PATCH] landing: make altitude handling before helper waypoint L more clever --- .../fw_pos_control_l1_main.cpp | 31 ++++++++++++++++--- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/src/modules/fw_pos_control_l1/fw_pos_control_l1_main.cpp b/src/modules/fw_pos_control_l1/fw_pos_control_l1_main.cpp index a68de45255..a908995289 100644 --- a/src/modules/fw_pos_control_l1/fw_pos_control_l1_main.cpp +++ b/src/modules/fw_pos_control_l1/fw_pos_control_l1_main.cpp @@ -279,6 +279,11 @@ private: */ void vehicle_setpoint_poll(); + /** + * Get Altitude on the landing glide slope + */ + float getLandingSlopeAbsoluteAltitude(float wp_distance, float wp_altitude, float landing_slope_angle_rad); + /** * Control position. */ @@ -624,6 +629,11 @@ FixedwingPositionControl::calculate_gndspeed_undershoot() } } +float FixedwingPositionControl::getLandingSlopeAbsoluteAltitude(float wp_distance, float wp_altitude, float landing_slope_angle_rad) +{ + return wp_distance * tanf(landing_slope_angle_rad) + wp_altitude; +} + bool FixedwingPositionControl::control_position(const math::Vector2f ¤t_position, const math::Vector2f &ground_speed, const struct vehicle_global_position_set_triplet_s &global_triplet) @@ -778,7 +788,10 @@ FixedwingPositionControl::control_position(const math::Vector2f ¤t_positio float airspeed_approach = (_parameters.airspeed_min + _parameters.airspeed_trim) / 2.0f; const float landing_slope_angle_rad = 20.0f/180.0f*M_PI_F; //xxx: param - float landing_slope_alt_desired = wp_distance * tanf(landing_slope_angle_rad) + _global_triplet.current.altitude; + const float landingslope_length = 64.0f; + const float L_wp_distance = cosf(landing_slope_angle_rad) * landingslope_length; + float L_altitude = getLandingSlopeAbsoluteAltitude(L_wp_distance, _global_triplet.current.altitude, landing_slope_angle_rad); + float landing_slope_alt_desired = getLandingSlopeAbsoluteAltitude(wp_distance, _global_triplet.current.altitude, landing_slope_angle_rad); if (altitude_error > -4.0f) { @@ -799,7 +812,7 @@ FixedwingPositionControl::control_position(const math::Vector2f ¤t_positio /* limit roll motion to prevent wings from touching the ground first */ _att_sp.roll_body = math::constrain(_att_sp.roll_body, math::radians(-10.0f), math::radians(10.0f)); - } else if (wp_distance < 60.0f || altitude_error > -20.0f) { + } else if (wp_distance < L_wp_distance) { /* minimize speed to approach speed, stay on glide slope */ _tecs.update_pitch_throttle(_R_nb, _att.pitch, _global_pos.alt, landing_slope_alt_desired, calculate_target_airspeed(airspeed_approach), @@ -811,10 +824,20 @@ FixedwingPositionControl::control_position(const math::Vector2f ¤t_positio } else { /* normal cruise speed - * intersect glide slope: if current position higher than slope sink to glide slope but continue horizontally if below slope */ + * intersect glide slope: + * if current position is higher or within 10m of slope follow the glide slope + * if current position is below slope -10m and above altitude at L (see documentation) continue horizontally + * if current position is below altitude at L, climb to altitude of L */ float altitude_desired = _global_pos.alt; - if (_global_pos.alt > landing_slope_alt_desired) { + if (_global_pos.alt > landing_slope_alt_desired - 10.0f) { + /* stay on slope */ altitude_desired = landing_slope_alt_desired; + } else if (_global_pos.alt < landing_slope_alt_desired - 10.0f && _global_pos.alt > L_altitude) { + /* continue horizontally */ + altitude_desired = _global_pos.alt; //xxx: dangerous, but we have the altitude < L_altitude protection + } else { + /* climb to L_altitude */ + altitude_desired = L_altitude; } _tecs.update_pitch_throttle(_R_nb, _att.pitch, _global_pos.alt, altitude_desired, calculate_target_airspeed(_parameters.airspeed_trim),