drives/gps: add new sensor_gnsss_relative msg

- for ublox this corresponds to NAV_RELPOSNED

msg/CMakeLists.txt

@@ -144,6 +144,7 @@ set(msg_files
 	sensor_combined.msg
 	sensor_correction.msg
 	sensor_gps.msg
+	sensor_gnss_relative.msg
 	sensor_gyro.msg
 	sensor_gyro_fft.msg
 	sensor_gyro_fifo.msg

msg/sensor_gnss_relative.msg

@@ -0,0 +1,30 @@
+# GNSS relative positioning information in NED frame. The NED frame is defined as the local topological system at the reference station.
+
+uint64 timestamp                  # time since system start (microseconds)
+uint64 timestamp_sample           # time since system start (microseconds)
+
+uint32 device_id                  # unique device ID for the sensor that does not change between power cycles
+
+uint64 time_utc_usec              # Timestamp (microseconds, UTC), this is the timestamp which comes from the gps module. It might be unavailable right after cold start, indicated by a value of 0
+
+uint16 reference_station_id       # Reference Station ID
+
+float32[3] position               # GPS NED relative position vector (m)
+float32[3] position_accuracy      # Accuracy of relative position (m)
+
+float32 heading                   # Heading of the relative position vector (radians)
+float32 heading_accuracy          # Accuracy of heading of the relative position vector (radians)
+
+float32 position_length
+float32 accuracy_length
+
+bool gnss_fix_ok                  # GNSS valid fix (i.e within DOP & accuracy masks)
+bool differential_solution        # differential corrections were applied
+bool relative_position_valid
+bool carrier_solution_floating    # carrier phase range solution with floating ambiguities
+bool carrier_solution_fixed       # carrier phase range solution with fixed ambiguities
+bool moving_base_mode             # if the receiver is operating in moving base mode
+bool reference_position_miss      # extrapolated reference position was used to compute moving base solution this epoch
+bool reference_observations_miss  # extrapolated reference observations were used to compute moving base solution this epoch
+bool heading_valid
+bool relative_position_normalized # the components of the relative position vector (including the high-precision parts) are normalized

src/drivers/gps/definitions.h

@@ -43,6 +43,7 @@
 #include <px4_platform_common/defines.h>
 #include <uORB/topics/satellite_info.h>
 #include <uORB/topics/sensor_gps.h>
+#include <uORB/topics/sensor_gnss_relative.h>
 
 #define GPS_INFO(...) PX4_INFO(__VA_ARGS__)
 #define GPS_WARN(...) PX4_WARN(__VA_ARGS__)

src/drivers/gps/gps.cpp

@@ -63,6 +63,7 @@
 #include <uORB/topics/gps_dump.h>
 #include <uORB/topics/gps_inject_data.h>
 #include <uORB/topics/sensor_gps.h>
+#include <uORB/topics/sensor_gnss_relative.h>
 
 #ifndef CONSTRAINED_FLASH
 # include "devices/src/ashtech.h"
@@ -181,6 +182,8 @@ private:
 	satellite_info_s		*_p_report_sat_info{nullptr};			///< pointer to uORB topic for satellite info
 
 	uORB::PublicationMulti<sensor_gps_s>	_report_gps_pos_pub{ORB_ID(sensor_gps)};	///< uORB pub for gps position
+	uORB::PublicationMulti<sensor_gnss_relative_s> _sensor_gnss_relative_pub{ORB_ID(sensor_gnss_relative)};
+
 	uORB::PublicationMulti<satellite_info_s>	_report_sat_info_pub{ORB_ID(satellite_info)};		///< uORB pub for satellite info
 
 	float				_rate{0.0f};					///< position update rate
@@ -220,6 +223,11 @@ private:
 	 */
 	void 				publishRTCMCorrections(uint8_t *data, size_t len);
 
+	/**
+	 * Publish RTCM corrections
+	 */
+	void 				publishRelativePosition(sensor_gnss_relative_s &gnss_relative);
+
 	/**
 	 * This is an abstraction for the poll on serial used.
 	 *
@@ -396,6 +404,13 @@ int GPS::callback(GPSCallbackType type, void *data1, int data2, void *user)
 		gps->dumpGpsData((uint8_t *)data1, (size_t)data2, gps_dump_comm_mode_t::RTCM, false);
 		break;
 
+	case GPSCallbackType::gotRelativePositionMessage:
+		if (data1 && data2 == sizeof(sensor_gnss_relative_s)) {
+			gps->publishRelativePosition(*static_cast<sensor_gnss_relative_s *>(data1));
+		}
+
+		break;
+
 	case GPSCallbackType::surveyInStatus:
 		/* not used */
 		break;
@@ -1184,6 +1199,14 @@ GPS::publishRTCMCorrections(uint8_t *data, size_t len)
 	}
 }
 
+void
+GPS::publishRelativePosition(sensor_gnss_relative_s &gnss_relative)
+{
+	gnss_relative.device_id = get_device_id();
+	gnss_relative.timestamp = hrt_absolute_time();
+	_sensor_gnss_relative_pub.publish(gnss_relative);
+}
+
 int
 GPS::custom_command(int argc, char *argv[])
 {

src/modules/logger/logged_topics.cpp

@@ -176,6 +176,7 @@ void LoggedTopics::add_default_topics()
 	add_optional_topic_multi("sensor_accel", 1000, 4);
 	add_optional_topic_multi("sensor_baro", 1000, 4);
 	add_topic_multi("sensor_gps", 1000, 2);
+	add_topic_multi("sensor_gnss_relative", 1000, 1);
 	add_optional_topic("pps_capture", 1000);
 	add_optional_topic_multi("sensor_gyro", 1000, 4);
 	add_optional_topic_multi("sensor_mag", 1000, 4);