ArduPlane: add AutoLand fixed-wing mode

ArduPlane/AP_Arming.cpp

@@ -378,6 +378,8 @@ bool AP_Arming_Plane::disarm(const AP_Arming::Method method, bool do_disarm_chec
     // DO_CHANGE_SPEED commands
     plane.new_airspeed_cm = -1;
 
+    // takeoff direction always cleared on disarm
+    plane.takeoff_state.takeoff_direction_initialized = false;
     send_arm_disarm_statustext("Throttle disarmed");
 
     return true;

ArduPlane/ArduPlane.cpp

@@ -684,11 +684,13 @@ void Plane::update_flight_stage(void)
             }
 #endif
             set_flight_stage(AP_FixedWing::FlightStage::NORMAL);
-        } else if (control_mode != &mode_takeoff) {
+        } else if ((control_mode != &mode_takeoff) && (control_mode != &mode_autoland)) {
             // If not in AUTO then assume normal operation for normal TECS operation.
             // This prevents TECS from being stuck in the wrong stage if you switch from
             // AUTO to, say, FBWB during a landing, an aborted landing or takeoff.
             set_flight_stage(AP_FixedWing::FlightStage::NORMAL);
+        } else  if (control_mode == &mode_autoland) {
+            set_flight_stage(AP_FixedWing::FlightStage::LAND);
         }
         return;
     }

ArduPlane/GCS_Mavlink.cpp

@@ -59,6 +59,7 @@ MAV_MODE GCS_MAVLINK_Plane::base_mode() const
     case Mode::Number::GUIDED:
     case Mode::Number::CIRCLE:
     case Mode::Number::TAKEOFF:
+    case Mode::Number::AUTOLAND:
 #if HAL_QUADPLANE_ENABLED
     case Mode::Number::QRTL:
     case Mode::Number::LOITER_ALT_QLAND:

ArduPlane/GCS_Plane.cpp

@@ -70,6 +70,7 @@ void GCS_Plane::update_vehicle_sensor_status_flags(void)
     case Mode::Number::GUIDED:
     case Mode::Number::CIRCLE:
     case Mode::Number::TAKEOFF:
+    case Mode::Number::AUTOLAND:
 #if HAL_QUADPLANE_ENABLED
     case Mode::Number::QRTL:
     case Mode::Number::LOITER_ALT_QLAND:

ArduPlane/Parameters.cpp

@@ -1028,6 +1028,10 @@ const AP_Param::Info Plane::var_info[] = {
     // @Path: mode_takeoff.cpp
     GOBJECT(mode_takeoff, "TKOFF_", ModeTakeoff),
     
+    // @Group: AUTOLAND_
+    // @Path: mode_autoland.cpp
+    GOBJECT(mode_autoland, "AUTOLAND_", ModeAutoLand),
+
 #if AP_PLANE_GLIDER_PULLUP_ENABLED
     // @Group: PUP_
     // @Path: pullup.cpp

ArduPlane/Parameters.h

@@ -363,6 +363,8 @@ public:
 
         k_param_pullup = 270,
         k_param_quicktune,
+        k_param_mode_autoland, 
+
     };
 
     AP_Int16 format_version;

ArduPlane/Plane.h

@@ -172,6 +172,7 @@ public:
     friend class ModeTakeoff;
     friend class ModeThermal;
     friend class ModeLoiterAltQLand;
+    friend class ModeAutoLand;
 
 #if AP_EXTERNAL_CONTROL_ENABLED
     friend class AP_ExternalControl_Plane;
@@ -326,6 +327,7 @@ private:
 #endif  // QAUTOTUNE_ENABLED
 #endif  // HAL_QUADPLANE_ENABLED
     ModeTakeoff mode_takeoff;
+    ModeAutoLand mode_autoland;
 #if HAL_SOARING_ENABLED
     ModeThermal mode_thermal;
 #endif
@@ -454,6 +456,9 @@ private:
         float throttle_lim_min;
         uint32_t throttle_max_timer_ms;
         uint32_t level_off_start_time_ms;
+        // Good candidate for keeping the initial time for TKOFF_THR_MAX_T.
+        int32_t takeoff_initial_direction; //deg
+        bool takeoff_direction_initialized;
     } takeoff_state;
 
     // ground steering controller state

ArduPlane/commands_logic.cpp

@@ -382,6 +382,7 @@ void Plane::do_takeoff(const AP_Mission::Mission_Command& cmd)
     // zero locked course
     steer_state.locked_course_err = 0;
     steer_state.hold_course_cd = -1;
+    takeoff_state.takeoff_direction_initialized = false;
     auto_state.baro_takeoff_alt = barometer.get_altitude();
 }
 
@@ -550,12 +551,15 @@ bool Plane::verify_takeoff()
     trust_ahrs_yaw |= ahrs.dcm_yaw_initialised();
 #endif
     if (trust_ahrs_yaw && steer_state.hold_course_cd == -1) {
-        const float min_gps_speed = 5;
+        const float min_gps_speed = GPS_GND_CRS_MIN_SPD;
         if (auto_state.takeoff_speed_time_ms == 0 && 
             gps.status() >= AP_GPS::GPS_OK_FIX_3D && 
             gps.ground_speed() > min_gps_speed &&
             hal.util->safety_switch_state() != AP_HAL::Util::SAFETY_DISARMED) {
             auto_state.takeoff_speed_time_ms = millis();
+            plane.takeoff_state.takeoff_initial_direction = wrap_360(plane.gps.ground_course() + plane.mode_autoland.landing_dir_off);
+            takeoff_state.takeoff_direction_initialized = true;
+            gcs().send_text(MAV_SEVERITY_INFO, "Autoland direction= %u",int(takeoff_state.takeoff_initial_direction));
         }
         if (auto_state.takeoff_speed_time_ms != 0 &&
             millis() - auto_state.takeoff_speed_time_ms >= 2000) {

ArduPlane/control_modes.cpp

@@ -83,6 +83,9 @@ Mode *Plane::mode_from_mode_num(const enum Mode::Number num)
     case Mode::Number::TAKEOFF:
         ret = &mode_takeoff;
         break;
+    case Mode::Number::AUTOLAND:
+        ret = &mode_autoland;
+        break;
     case Mode::Number::THERMAL:
 #if HAL_SOARING_ENABLED
         ret = &mode_thermal;

ArduPlane/defines.h

@@ -10,6 +10,8 @@
 
 #define TAKEOFF_RUDDER_WARNING_TIMEOUT 3000 //ms that GCS warning about not returning arming rudder to neutral repeats
 
+#define GPS_GND_CRS_MIN_SPD 5 // m/s, used to set when takeoff_initial_direction is captured in NAV_TAKEOFF and Mode TAKEOFF
+
 // failsafe
 // ----------------------
 enum failsafe_state {
@@ -45,6 +47,7 @@ enum failsafe_action_long {
     FS_ACTION_LONG_GLIDE = 2,
     FS_ACTION_LONG_PARACHUTE = 3,
     FS_ACTION_LONG_AUTO = 4,
+    FS_ACTION_LONG_AUTOLAND = 5,
 };
 
 // type of stick mixing enabled

ArduPlane/events.cpp

@@ -65,7 +65,8 @@ void Plane::failsafe_short_on_event(enum failsafe_state fstype, ModeReason reaso
         break;
 #endif // HAL_QUADPLANE_ENABLED
 
-    case Mode::Number::AUTO: {
+    case Mode::Number::AUTO:
+    case Mode::Number::AUTOLAND: {
         if (failsafe_in_landing_sequence()) {
             // don't failsafe in a landing sequence
             break;
@@ -145,6 +146,10 @@ void Plane::failsafe_long_on_event(enum failsafe_state fstype, ModeReason reason
             set_mode(mode_fbwa, reason);
         } else if (g.fs_action_long == FS_ACTION_LONG_AUTO) {
             set_mode(mode_auto, reason);
+        } else if (g.fs_action_long == FS_ACTION_LONG_AUTOLAND) {
+            if(!set_mode(mode_autoland, reason)) {
+               set_mode(mode_rtl, reason);
+            }
         } else {
             set_mode(mode_rtl, reason);
         }
@@ -194,6 +199,10 @@ void Plane::failsafe_long_on_event(enum failsafe_state fstype, ModeReason reason
             set_mode(mode_fbwa, reason);
         } else if (g.fs_action_long == FS_ACTION_LONG_AUTO) {
             set_mode(mode_auto, reason);
+        } else if (g.fs_action_long == FS_ACTION_LONG_AUTOLAND) {
+            if(!set_mode(mode_autoland, reason)) {
+               set_mode(mode_rtl, reason);
+            }            
         } else if (g.fs_action_long == FS_ACTION_LONG_RTL) {
             set_mode(mode_rtl, reason);
         }
@@ -202,6 +211,8 @@ void Plane::failsafe_long_on_event(enum failsafe_state fstype, ModeReason reason
     case Mode::Number::RTL:
         if (g.fs_action_long == FS_ACTION_LONG_AUTO) {
             set_mode(mode_auto, reason);
+        } else if (g.fs_action_long == FS_ACTION_LONG_AUTOLAND) {
+            set_mode(mode_autoland, reason);
         }
         break;
 #if HAL_QUADPLANE_ENABLED
@@ -210,6 +221,7 @@ void Plane::failsafe_long_on_event(enum failsafe_state fstype, ModeReason reason
     case Mode::Number::LOITER_ALT_QLAND:
 #endif
     case Mode::Number::INITIALISING:
+    case Mode::Number::AUTOLAND:
         break;
     }
     gcs().send_text(MAV_SEVERITY_WARNING, "%s Failsafe On: %s", (reason == ModeReason:: GCS_FAILSAFE) ? "GCS" : "RC Long", control_mode->name());

ArduPlane/mode.cpp

@@ -142,6 +142,10 @@ bool Mode::enter()
         // Make sure the flight stage is correct for the new mode
         plane.update_flight_stage();
         
+        // reset landing state
+        plane.landing.reset();
+
+
 #if HAL_QUADPLANE_ENABLED
         if (quadplane.enabled()) {
             float aspeed;

ArduPlane/mode.h

@@ -61,6 +61,7 @@ public:
 #if HAL_QUADPLANE_ENABLED
         LOITER_ALT_QLAND = 25,
 #endif
+        AUTOLAND      = 26,
     };
 
     // Constructor
@@ -858,6 +859,40 @@ private:
 
 };
 
+class ModeAutoLand: public Mode
+{
+public:
+    ModeAutoLand();
+
+    Number mode_number() const override { return Number::AUTOLAND; }
+    const char *name() const override { return "AUTOLAND"; }
+    const char *name4() const override { return "ALND"; }
+
+    // methods that affect movement of the vehicle in this mode
+    void update() override;
+
+    void navigate() override;
+
+    bool allows_throttle_nudging() const override { return true; }
+
+    bool does_auto_navigation() const override { return true; }
+
+    bool does_auto_throttle() const override { return true; }
+    
+
+    // var_info for holding parameter information
+    static const struct AP_Param::GroupInfo var_info[];
+
+    AP_Int16 final_wp_alt;
+    AP_Int16 final_wp_dist;
+    AP_Int16 landing_dir_off;
+
+protected:
+    bool _enter() override;
+    AP_Mission::Mission_Command cmd;
+    bool land_started;
+};
+
 #if HAL_SOARING_ENABLED
 
 class ModeThermal: public Mode

ArduPlane/mode_autoland.cpp

@@ -0,0 +1,114 @@
+#include "mode.h"
+#include "Plane.h"
+#include <GCS_MAVLink/GCS.h>
+
+/*
+  mode AutoLand parameters
+ */
+const AP_Param::GroupInfo ModeAutoLand::var_info[] = {
+    // @Param: WP_ALT
+    // @DisplayName: Final approach WP altitude
+    // @Description: This is the target altitude above HOME for final approach waypoint
+    // @Range: 0 200
+    // @Increment: 1
+    // @Units: m
+    // @User: Standard
+    AP_GROUPINFO("WP_ALT", 1, ModeAutoLand, final_wp_alt, 55),
+
+    // @Param: WP_DIST
+    // @DisplayName: Final approach WP distance
+    // @Description: This is the distance from Home that the final approach waypoint is set. The waypoint point will be in the opposite direction of takeoff (the direction the plane is facing when the plane sets its takeoff heading)
+    // @Range: 0 700
+    // @Increment: 1
+    // @Units: m
+    // @User: Standard
+    AP_GROUPINFO("WP_DIST", 2, ModeAutoLand, final_wp_dist, 400),
+
+    // @Param: DIR_OFF
+    // @DisplayName: Landing direction offset from takeoff
+    // @Description: The captured takeoff direction (at arming,if TKOFF_OPTION bit1 is set, or after ground course is established in autotakeoffs)is offset by this amount to create a different landing direction and approach.
+    // @Range: -360 360
+    // @Increment: 1
+    // @Units: deg
+    // @User: Standard
+    AP_GROUPINFO("DIR_OFF", 3, ModeAutoLand, landing_dir_off, 0),
+
+    AP_GROUPEND
+};
+
+ModeAutoLand::ModeAutoLand() :
+    Mode()
+{
+    AP_Param::setup_object_defaults(this, var_info);
+}
+
+bool ModeAutoLand::_enter()
+{             
+    //must be flying to enter
+    if (!plane.is_flying()) { 
+        gcs().send_text(MAV_SEVERITY_WARNING, "Must already be flying!"); 
+        return false;
+    }
+    
+    //takeoff direction must be set and must not be a quadplane, otherwise since flying switch to RTL so this can be used as FS action
+#if HAL_QUADPLANE_ENABLED
+    if (quadplane.available()) {
+        gcs().send_text(MAV_SEVERITY_WARNING, "AutoLand is fixed wing only mode"); 
+        return false; 
+    }
+#endif
+    if (!plane.takeoff_state.takeoff_direction_initialized) {
+        gcs().send_text(MAV_SEVERITY_WARNING, "Takeoff initial direction not set,must use autotakeoff");
+        return false;
+    }
+
+
+    //setup final approach waypoint
+    plane.prev_WP_loc = plane.current_loc;
+    const Location &home = ahrs.get_home();
+    plane.set_target_altitude_current();
+    plane.next_WP_loc = home;
+    uint16_t bearing_cd = wrap_360_cd((plane.takeoff_state.takeoff_initial_direction + 180)*100);
+    plane.next_WP_loc.offset_bearing(bearing_cd * 0.01f, final_wp_dist);
+    plane.next_WP_loc.set_alt_m(final_wp_alt, Location::AltFrame::ABOVE_HOME);
+    
+    // create a command to fly to final approach waypoint and start it
+    cmd.id = MAV_CMD_NAV_WAYPOINT;
+    cmd.content.location = plane.next_WP_loc;
+    plane.start_command(cmd);
+    land_started = false;
+    return true;
+}
+
+void ModeAutoLand::update()
+{
+    plane.calc_nav_roll();
+    plane.calc_nav_pitch();
+    plane.set_offset_altitude_location(plane.prev_WP_loc, plane.next_WP_loc);
+    if (plane.landing.is_throttle_suppressed()) {
+       // if landing is considered complete throttle is never allowed, regardless of landing type
+       SRV_Channels::set_output_scaled(SRV_Channel::k_throttle, 0.0);
+    } else {
+       plane.calc_throttle();
+    }
+}
+
+void ModeAutoLand::navigate()
+{    
+    // check to see if if we have reached final approach waypoint, switch to NAV_LAND command and start it once if so
+    if (!land_started){
+        if (plane.verify_nav_wp(cmd)){
+            const Location &home_loc = ahrs.get_home();
+            cmd.id = MAV_CMD_NAV_LAND;
+            cmd.content.location = home_loc;
+            land_started = true;
+            plane.prev_WP_loc = plane.current_loc;
+            plane.next_WP_loc = home_loc;
+            plane.start_command(cmd);
+        }
+        return;
+    //otherwise keep flying the current command   
+    } else {
+       plane.verify_command(cmd);
+    }
+}

ArduPlane/mode_takeoff.cpp

@@ -134,6 +134,7 @@ void ModeTakeoff::update()
                 plane.takeoff_state.throttle_max_timer_ms = millis();
                 takeoff_mode_setup = true;
                 plane.steer_state.hold_course_cd = wrap_360_cd(direction*100); // Necessary to allow Plane::takeoff_calc_roll() to function.
+                plane.takeoff_state.takeoff_direction_initialized = false;
             }
         }
     }
@@ -143,6 +144,15 @@ void ModeTakeoff::update()
         takeoff_mode_setup = false;
     }
     
+    // set takeoff_initial_direction
+    const float min_gps_speed = GPS_GND_CRS_MIN_SPD;
+    if (!(plane.takeoff_state.takeoff_direction_initialized) && (plane.gps.ground_speed() > min_gps_speed)
+       && (plane.flight_stage == AP_FixedWing::FlightStage::TAKEOFF)) {
+       plane.takeoff_state.takeoff_initial_direction = wrap_360(plane.gps.ground_course() + plane.mode_autoland.landing_dir_off);
+       plane.takeoff_state.takeoff_direction_initialized = true;
+       gcs().send_text(MAV_SEVERITY_INFO, "Autoland direction= %u",int(plane.takeoff_state.takeoff_initial_direction));
+    }
+
     // We update the waypoint to follow once we're past TKOFF_LVL_ALT or we
     // pass the target location. The check for target location prevents us
     // flying towards a wrong location if we can't climb.

ArduPlane/takeoff.cpp

@@ -22,12 +22,13 @@ bool Plane::auto_takeoff_check(void)
         return false;
     }
 
-    // Reset states if process has been interrupted
+    // Reset states if process has been interrupted, except takeoff_direction_initialized if set
+    bool takeoff_dir_initialized = takeoff_state.takeoff_direction_initialized;
      if (takeoff_state.last_check_ms && (now - takeoff_state.last_check_ms) > 200) {
          memset(&takeoff_state, 0, sizeof(takeoff_state));
+         takeoff_state.takeoff_direction_initialized = takeoff_dir_initialized; //restore dir init state
          return false;
      }
-
     takeoff_state.last_check_ms = now;
     
     //check if waiting for rudder neutral after rudder arm