gps blend: move blending logic to class

src/modules/sensors/vehicle_gps_position/CMakeLists.txt

@@ -34,5 +34,7 @@
 px4_add_library(vehicle_gps_position
 	VehicleGPSPosition.cpp
 	VehicleGPSPosition.hpp
+	gps_blending.cpp
+	gps_blending.hpp
 )
 target_link_libraries(vehicle_gps_position PRIVATE ecl_geo px4_work_queue)

src/modules/sensors/vehicle_gps_position/VehicleGPSPosition.hpp

@@ -47,6 +47,8 @@
 #include <uORB/topics/sensor_gps.h>
 #include <uORB/topics/vehicle_gps_position.h>
 
+#include "gps_blending.hpp"
+
 using namespace time_literals;
 
 namespace sensors
@@ -64,49 +66,18 @@ public:
 	void PrintStatus();
 
 private:
-	// define max number of GPS receivers supported and 0 base instance used to access virtual 'blended' GPS solution
-	static constexpr int GPS_MAX_RECEIVERS = 2;
-	static constexpr int GPS_BLENDED_INSTANCE = GPS_MAX_RECEIVERS;
-
 	void Run() override;
 
 	void ParametersUpdate(bool force = false);
 	void Publish(const sensor_gps_s &gps, uint8_t selected);
 
-	/*
-	 * Update the internal state estimate for a blended GPS solution that is a weighted average of the phsyical
-	 * receiver solutions. This internal state cannot be used directly by estimators because if physical receivers
-	 * have significant position differences, variation in receiver estimated accuracy will cause undesirable
-	 * variation in the position solution.
-	*/
-	bool blend_gps_data();
-
-	/*
-	 * Calculate internal states used to blend GPS data from multiple receivers using weightings calculated
-	 * by calc_blend_weights()
-	 */
-	sensor_gps_s gps_blend_states(float blend_weights[GPS_MAX_RECEIVERS]) const;
-
-	/*
-	 * The location in gps_blended_state will move around as the relative accuracy changes.
-	 * To mitigate this effect a low-pass filtered offset from each GPS location to the blended location is
-	 * calculated.
-	*/
-	void update_gps_offsets(const sensor_gps_s &gps_blended_state);
-
-	/*
-	 Calculate GPS output that is a blend of the offset corrected physical receiver data
-	*/
-	void calc_gps_blend_output(sensor_gps_s &gps_blended_state, float blend_weights[GPS_MAX_RECEIVERS]) const;
-
 	// defines used to specify the mask position for use of different accuracy metrics in the GPS blending algorithm
 	static constexpr uint8_t BLEND_MASK_USE_SPD_ACC  = 1;
 	static constexpr uint8_t BLEND_MASK_USE_HPOS_ACC = 2;
 	static constexpr uint8_t BLEND_MASK_USE_VPOS_ACC = 4;
 
-	// Set the GPS timeout to 2s, after which a receiver will be ignored
+	// define max number of GPS receivers supported
-	static constexpr hrt_abstime GPS_TIMEOUT_US = 2_s;
+	static constexpr int GPS_MAX_RECEIVERS = 2;
-	static constexpr float GPS_TIMEOUT_S = (GPS_TIMEOUT_US / 1e6f);
 
 	uORB::Publication<vehicle_gps_position_s> _vehicle_gps_position_pub{ORB_ID(vehicle_gps_position)};
 
@@ -119,16 +90,7 @@ private:
 
 	perf_counter_t _cycle_perf{perf_alloc(PC_ELAPSED, MODULE_NAME": cycle")};
 
-	sensor_gps_s _gps_state[GPS_MAX_RECEIVERS] {}; ///< internal state data for the physical GPS
+	GpsBlending<GPS_MAX_RECEIVERS> _gps_blending;
-
-	matrix::Vector2f _NE_pos_offset_m[GPS_MAX_RECEIVERS] {}; ///< Filtered North,East position offset from GPS instance to blended solution in _output_state.location (m)
-	float _hgt_offset_mm[GPS_MAX_RECEIVERS] {};	///< Filtered height offset from GPS instance relative to blended solution in _output_state.location (mm)
-
-	uint64_t _time_prev_us[GPS_MAX_RECEIVERS] {};	///< the previous value of time_us for that GPS instance - used to detect new data.
-	uint8_t _gps_time_ref_index{0};			///< index of the receiver that is used as the timing reference for the blending update
-	uint8_t _gps_newest_index{0};			///< index of the physical receiver with the newest data
-	uint8_t _gps_slowest_index{0};			///< index of the physical receiver with the slowest update rate
-	float _gps_dt[GPS_MAX_RECEIVERS] {};		///< average time step in seconds.
 
 	DEFINE_PARAMETERS(
 		(ParamInt<px4::params::SENS_GPS_MASK>) _param_sens_gps_mask,

src/modules/sensors/vehicle_gps_position/gps_blending.hpp

@@ -0,0 +1,131 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2021 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file gps_blending.hpp
+ */
+
+#pragma once
+
+#include <drivers/drv_hrt.h>
+#include <lib/matrix/matrix/math.hpp>
+#include <px4_platform_common/defines.h>
+#include <uORB/topics/sensor_gps.h>
+
+using namespace time_literals;
+
+template<int GPS_MAX_RECEIVERS>
+class GpsBlending
+{
+public:
+	// Set the GPS timeout to 2s, after which a receiver will be ignored
+	static constexpr hrt_abstime GPS_TIMEOUT_US = 2_s;
+	static constexpr float GPS_TIMEOUT_S = (GPS_TIMEOUT_US / 1e6f);
+
+
+	GpsBlending() = default;
+	~GpsBlending() = default;
+
+	void setGpsData(const sensor_gps_s &gps_data, int instance)
+	{
+		_gps_state[instance] = gps_data;
+		_gps_updated[instance] = true;
+	}
+	void setBlendingUseSpeedAccuracy(bool enabled) { _blend_use_spd_acc = enabled; }
+	void setBlendingUseHPosAccuracy(bool enabled) { _blend_use_hpos_acc = enabled; }
+	void setBlendingUseVPosAccuracy(bool enabled) { _blend_use_vpos_acc = enabled; }
+	void setBlendingTimeConstant(float tau) { _blending_time_constant = tau; }
+
+	void update();
+
+	bool isNewOutputDataAvailable() const { return _is_new_output_data_available; }
+	const sensor_gps_s &getOutputGpsData() const
+	{
+		if (_selected_gps < GPS_MAX_RECEIVERS) {
+			return _gps_state[_selected_gps];
+
+		} else {
+			return _gps_blended_state;
+		}
+	}
+	int getSelectedGps() const { return _selected_gps; }
+
+private:
+	/*
+	 * Update the internal state estimate for a blended GPS solution that is a weighted average of the phsyical
+	 * receiver solutions. This internal state cannot be used directly by estimators because if physical receivers
+	 * have significant position differences, variation in receiver estimated accuracy will cause undesirable
+	 * variation in the position solution.
+	*/
+	bool blend_gps_data();
+
+	/*
+	 * Calculate internal states used to blend GPS data from multiple receivers using weightings calculated
+	 * by calc_blend_weights()
+	 */
+	sensor_gps_s gps_blend_states(float blend_weights[GPS_MAX_RECEIVERS]) const;
+
+	/*
+	 * The location in gps_blended_state will move around as the relative accuracy changes.
+	 * To mitigate this effect a low-pass filtered offset from each GPS location to the blended location is
+	 * calculated.
+	*/
+	void update_gps_offsets(const sensor_gps_s &gps_blended_state);
+
+	/*
+	 Calculate GPS output that is a blend of the offset corrected physical receiver data
+	*/
+	void calc_gps_blend_output(sensor_gps_s &gps_blended_state, float blend_weights[GPS_MAX_RECEIVERS]) const;
+
+	sensor_gps_s _gps_state[GPS_MAX_RECEIVERS] {}; ///< internal state data for the physical GPS
+	sensor_gps_s _gps_blended_state {};
+	bool _gps_updated[GPS_MAX_RECEIVERS] {};
+	int _selected_gps{0};
+
+	bool _is_new_output_data_available{false};
+
+	matrix::Vector2f _NE_pos_offset_m[GPS_MAX_RECEIVERS] {}; ///< Filtered North,East position offset from GPS instance to blended solution in _output_state.location (m)
+	float _hgt_offset_mm[GPS_MAX_RECEIVERS] {};	///< Filtered height offset from GPS instance relative to blended solution in _output_state.location (mm)
+
+	uint64_t _time_prev_us[GPS_MAX_RECEIVERS] {};	///< the previous value of time_us for that GPS instance - used to detect new data.
+	uint8_t _gps_time_ref_index{0};			///< index of the receiver that is used as the timing reference for the blending update
+	uint8_t _gps_newest_index{0};			///< index of the physical receiver with the newest data
+	uint8_t _gps_slowest_index{0};			///< index of the physical receiver with the slowest update rate
+	float _gps_dt[GPS_MAX_RECEIVERS] {};		///< average time step in seconds.
+
+	bool _blend_use_spd_acc{false};
+	bool _blend_use_hpos_acc{false};
+	bool _blend_use_vpos_acc{false};
+
+	float _blending_time_constant{0.f};
+};