px4_autopilot/test/test_EKF_airspeed.cpp

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/**
 * Test the fusion of airspeed data
 * @author Kamil Ritz <ka.ritz@hotmail.com>
 */

#include <gtest/gtest.h>
#include "EKF/ekf.h"
#include "sensor_simulator/sensor_simulator.h"
#include "sensor_simulator/ekf_wrapper.h"


class EkfAirspeedTest : public ::testing::Test {
 public:

	EkfAirspeedTest(): ::testing::Test(),
	_ekf{std::make_shared<Ekf>()},
	_sensor_simulator(_ekf),
	_ekf_wrapper(_ekf),
	_quat_sim(Eulerf(0.0f, 0.0f, math::radians(45.0f))) {};

	std::shared_ptr<Ekf> _ekf;
	SensorSimulator _sensor_simulator;
	EkfWrapper _ekf_wrapper;
	const Quatf _quat_sim;

	// Setup the Ekf with synthetic measurements
	void SetUp() override
	{
		_ekf->init(0);
		_sensor_simulator.simulateOrientation(_quat_sim);
		_sensor_simulator.runSeconds(2);
	}

	// Use this method to clean up any memory, network etc. after each test
	void TearDown() override
	{
	}
};

TEST_F(EkfAirspeedTest, testWindVelocityEstimation)
{

	const Vector3f simulated_velocity_earth(0.0f,1.5f,0.0f);
	const Vector2f airspeed_body(0.4f, 0.0f);
	_ekf_wrapper.enableExternalVisionVelocityFusion();
	_sensor_simulator._vio.setVelocity(simulated_velocity_earth);
	_sensor_simulator.startExternalVision();

	_ekf->set_in_air_status(true);
	_sensor_simulator.startAirspeedSensor();
	_sensor_simulator._airspeed.setData(airspeed_body(0), airspeed_body(0));

	// Wind estimation is rather slow
	_sensor_simulator.runSeconds(15);

	EXPECT_TRUE(_ekf_wrapper.isWindVelocityEstimated());

	const Vector3f vel = _ekf_wrapper.getVelocity();
	const Vector2f vel_wind_earth = _ekf_wrapper.getWindVelocity();
	const float height_before_pressure_correction = _ekf_wrapper.getPosition()(2);

	const Dcmf R_to_earth_sim(_quat_sim);
	EXPECT_TRUE(matrix::isEqual(vel, simulated_velocity_earth));
 	const Vector3f vel_wind_expected = simulated_velocity_earth - R_to_earth_sim * (Vector3f(airspeed_body(0), airspeed_body(1), 0.0f));
	EXPECT_TRUE(matrix::isEqual(vel_wind_earth, Vector2f(vel_wind_expected.slice<2,1>(0,0))));
	EXPECT_FLOAT_EQ(height_before_pressure_correction, 0.0f);

	// Apply height correction
	const float static_pressure_coef_xp = 1.0f;
	const float static_pressure_coef_yp = -1.0f;	// not used as wind direction is along x axis
	parameters* _params = _ekf->getParamHandle();
	_params->static_pressure_coef_xp = static_pressure_coef_xp;
	_params->static_pressure_coef_yp = static_pressure_coef_yp;
	float expected_height_difference = 0.5f * static_pressure_coef_xp * airspeed_body(0) * airspeed_body(0) / CONSTANTS_ONE_G;

	_sensor_simulator.runSeconds(20);

	const float height_after_pressure_correction = _ekf_wrapper.getPosition()(2);
	// height increase means that state z decrease due to z axis pointing down
	const float expected_height_after_pressure_correction = height_before_pressure_correction -
								expected_height_difference;

	EXPECT_NEAR(height_after_pressure_correction, expected_height_after_pressure_correction, 1e-5f);

}