AP_Mission: add winch support

libraries/AP_Mission/AP_Mission.cpp

@@ -806,6 +806,13 @@ MAV_MISSION_RESULT AP_Mission::mavlink_int_to_mission_cmd(const mavlink_mission_
         cmd.content.set_yaw_speed.relative_angle = packet.param3;   // 0 = absolute angle, 1 = relative angle
         break;
 
+    case MAV_CMD_DO_WINCH:                              // MAV ID: 42600
+        cmd.content.winch.num = packet.param1;          // winch number
+        cmd.content.winch.action = packet.param2;       // action (0 = relax, 1 = length control, 2 = rate control).  See WINCH_ACTION enum
+        cmd.content.winch.release_length = packet.param3;   // cable distance to unwind in meters, negative numbers to wind in cable
+        cmd.content.winch.release_rate = packet.param4; // release rate in meters/second
+        break;
+
     default:
         // unrecognised command
         return MAV_MISSION_UNSUPPORTED;
@@ -1255,6 +1262,13 @@ bool AP_Mission::mission_cmd_to_mavlink_int(const AP_Mission::Mission_Command& c
         packet.param3 = cmd.content.set_yaw_speed.relative_angle;   // 0 = absolute angle, 1 = relative angle
         break;
 
+    case MAV_CMD_DO_WINCH:
+        packet.param1 = cmd.content.winch.num;              // winch number
+        packet.param2 = cmd.content.winch.action;           // action (0 = relax, 1 = length control, 2 = rate control).  See WINCH_ACTION enum
+        packet.param3 = cmd.content.winch.release_length;   // cable distance to unwind in meters, negative numbers to wind in cable
+        packet.param4 = cmd.content.winch.release_rate;     // release rate in meters/second
+        break;
+
     default:
         // unrecognised command
         return false;

libraries/AP_Mission/AP_Mission.h

@@ -184,6 +184,14 @@ public:
         uint8_t relative_angle; // 0 = absolute angle, 1 = relative angle
     };
 
+    // winch command structure
+    struct PACKED Winch_Command {
+        uint8_t num;            // winch number
+        uint8_t action;         // action (0 = relax, 1 = length control, 2 = rate control)
+        float release_length;   // cable distance to unwind in meters, negative numbers to wind in cable
+        float release_rate;     // release rate in meters/second
+    };
+
     union PACKED Content {
         // jump structure
         Jump_Command jump;
@@ -245,6 +253,9 @@ public:
         // navigation delay
         Set_Yaw_Speed set_yaw_speed;
 
+        // do-winch
+        Winch_Command winch;
+
         // location
         Location location;      // Waypoint location