FlightModeManager/FixedwingPositionControl: robustify vehicle command parameter casting

src/modules/flight_mode_manager/FlightModeManager.cpp

@@ -444,8 +444,9 @@ void FlightModeManager::handleCommand()
 
 		} else if (_current_task.task) {
 			// check for other commands not related to task switching
-			if (command.command == vehicle_command_s::VEHICLE_CMD_DO_CHANGE_SPEED && command.param2 >= 0
-			    && (uint8_t)command.param1 == vehicle_command_s::SPEED_TYPE_GROUNDSPEED) {
+			if ((command.command == vehicle_command_s::VEHICLE_CMD_DO_CHANGE_SPEED)
+			    && (static_cast<uint8_t>(command.param1 + .5f) == vehicle_command_s::SPEED_TYPE_GROUNDSPEED)
+			    && (command.param2 > 0.f)) {
 				_current_task.task->setCruisingSpeed(command.param2);
 			}
 		}

src/modules/fw_pos_control_l1/FixedwingPositionControl.cpp

@@ -258,8 +258,9 @@ FixedwingPositionControl::vehicle_command_poll()
 				abort_landing(true);
 			}
 
-		} else if (vehicle_command.command == vehicle_command_s::VEHICLE_CMD_DO_CHANGE_SPEED
-			   && (uint8_t)vehicle_command.param1 == vehicle_command_s::SPEED_TYPE_AIRSPEED && vehicle_command.param2 > 0) {
+		} else if ((vehicle_command.command == vehicle_command_s::VEHICLE_CMD_DO_CHANGE_SPEED)
+			   && (static_cast<uint8_t>(vehicle_command.param1 + .5f) == vehicle_command_s::SPEED_TYPE_AIRSPEED)
+			   && (vehicle_command.param2 > 0.f)) {
 
 			if (_control_mode_current == FW_POSCTRL_MODE_AUTO) {
 				_pos_sp_triplet.current.cruising_speed = vehicle_command.param2;

src/modules/fw_pos_control_l1/FixedwingPositionControl.hpp

@@ -266,7 +266,7 @@ private:
 
 	float _manual_control_setpoint_altitude{0.0f};
 	float _manual_control_setpoint_airspeed{0.0f};
-	float _commanded_airspeed_setpoint{(float)NAN};		///< airspeed setpoint for manual modes commanded via MAV_CMD_DO_CHANGE_SPEED
+	float _commanded_airspeed_setpoint{NAN};		///< airspeed setpoint for manual modes commanded via MAV_CMD_DO_CHANGE_SPEED
 
 	hrt_abstime _time_in_fixed_bank_loiter{0};