feat(ekf2): generalize engine warmup mode

This is not only needed for engine warmup but in general, when the
vehicle is static on the ground, relying on fixed position to maintain a
valid global position estimate before takeoff, even when bumping it or
starting the engine.

src/lib/parameters/param_translation.cpp

@@ -223,5 +223,15 @@ param_modify_on_import_ret param_modify_on_import(bson_node_t node)
 		}
 	}
 
+	// 2026-03-19: translate EKF2_ENGINE_WRM to EKF2_POS_LOCK
+	{
+		if (strcmp("EKF2_ENGINE_WRM", node->name) == 0) {
+			int32_t delay_ms = static_cast<int32_t>(node->d);
+			param_set(param_find("EKF2_POS_LOCK"), &delay_ms);
+			PX4_INFO("migrating %s -> %s", "EKF2_ENGINE_WRM", "EKF2_POS_LOCK");
+			return param_modify_on_import_ret::PARAM_MODIFIED;
+		}
+	}
+
 	return param_modify_on_import_ret::PARAM_NOT_MODIFIED;
 }

src/modules/ekf2/EKF2.cpp

@@ -2638,8 +2638,7 @@ void EKF2::UpdateSystemFlagsSample(ekf2_timestamps_s &ekf2_timestamps)
 			flags.in_air = !vehicle_land_detected.landed;
 			flags.gnd_effect = vehicle_land_detected.in_ground_effect;
 
-			// Enable constant position fusion for engine warmup when landed and armed
+			flags.constant_pos = _param_ekf2_pos_lock.get() && !flags.in_air && _ekf.isGlobalHorizontalPositionValid();
-			flags.constant_pos = _param_ekf2_engine_wrm.get() && !flags.in_air && armed;
 		}
 
 		launch_detection_status_s launch_detection_status;
@@ -2647,7 +2646,7 @@ void EKF2::UpdateSystemFlagsSample(ekf2_timestamps_s &ekf2_timestamps)
 		if (_launch_detection_status_sub.copy(&launch_detection_status)
 		    && (ekf2_timestamps.timestamp < launch_detection_status.timestamp + 3_s)) {
 
-			flags.constant_pos = (launch_detection_status.launch_detection_state ==
+			flags.constant_pos |= (launch_detection_status.launch_detection_state ==
 					       launch_detection_status_s::STATE_WAITING_FOR_LAUNCH);
 		}
 

src/modules/ekf2/EKF2.hpp

@@ -487,7 +487,7 @@ private:
 		(ParamExtFloat<px4::params::EKF2_DELAY_MAX>) _param_ekf2_delay_max,
 		(ParamExtInt<px4::params::EKF2_IMU_CTRL>) _param_ekf2_imu_ctrl,
 		(ParamExtFloat<px4::params::EKF2_VEL_LIM>) _param_ekf2_vel_lim,
-		(ParamBool<px4::params::EKF2_ENGINE_WRM>) _param_ekf2_engine_wrm,
+		(ParamBool<px4::params::EKF2_POS_LOCK>) _param_ekf2_pos_lock,
 
 #if defined(CONFIG_EKF2_AUXVEL)
 		(ParamExtFloat<px4::params::EKF2_AVEL_DELAY>)

src/modules/ekf2/module.yaml

@@ -186,10 +186,9 @@ parameters:
       unit: m/s
       decimal: 1
 
-    EKF2_ENGINE_WRM:
+    EKF2_POS_LOCK:
       description:
-        short: Enable constant position fusion during engine warmup
+        short: Enable constant position fusion while on ground
-        long: When enabled, constant position fusion is enabled when the vehicle is landed and armed.
+        long: When enabled, constant position fusion is enabled when the vehicle is landeded if position has been initialized but has currently no vel/pos aiding.
-         This is intended for IC engine warmup (e.g., fuel engines on catapult) to allow mode transitions to auto/takeoff despite vibrations from running engines.
       type: boolean
       default: 0