PX4-Autopilot/src/modules/mag_bias_estimator/MagBiasEstimator.cpp

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#include "MagBiasEstimator.hpp"

using namespace time_literals;
using matrix::Vector3f;

namespace mag_bias_estimator
{

MagBiasEstimator::MagBiasEstimator() :
	ModuleParams(nullptr),
	ScheduledWorkItem(MODULE_NAME, px4::wq_configurations::lp_default)
{
}

MagBiasEstimator::~MagBiasEstimator()
{
	perf_free(_cycle_perf);
}

int MagBiasEstimator::task_spawn(int argc, char *argv[])
{
	MagBiasEstimator *obj = new MagBiasEstimator();

	if (!obj) {
		PX4_ERR("alloc failed");
		return -1;
	}

	_object.store(obj);
	_task_id = task_id_is_work_queue;

	/* Schedule a cycle to start things. */
	obj->start();

	return 0;
}

void MagBiasEstimator::start()
{
	ScheduleOnInterval(20_ms); // 50 Hz
}

void MagBiasEstimator::Run()
{
	if (should_exit()) {
		ScheduleClear();
		exit_and_cleanup();
	}

	if (_vehicle_status_sub.updated()) {
		vehicle_status_s vehicle_status;

		if (_vehicle_status_sub.copy(&vehicle_status)) {
			if (_arming_state != vehicle_status.arming_state) {
				_armed = vehicle_status.arming_state == vehicle_status_s::ARMING_STATE_ARMED;

				// reset on any arming state change
				for (int mag_index = 0; mag_index < MAX_SENSOR_COUNT; mag_index++) {
					_reset_field_estimator[mag_index] = true;
				}

				_arming_state = vehicle_status.arming_state;
			}
		}
	}

	// only run when disarmed
	if (_armed) {
		return;
	}

	// check for parameter updates
	if (_parameter_update_sub.updated()) {
		// clear update
		parameter_update_s pupdate;
		_parameter_update_sub.copy(&pupdate);

		// update parameters from storage
		updateParams();

		for (int mag_index = 0; mag_index < MAX_SENSOR_COUNT; mag_index++) {
			const auto calibration_count = _calibration[mag_index].calibration_count();
			_calibration[mag_index].ParametersUpdate();

			if (calibration_count != _calibration[mag_index].calibration_count()) {
				_reset_field_estimator[mag_index] = true;
			}

			_bias_estimator[mag_index].setLearningGain(_param_mbe_learn_gain.get());
		}
	}

	if (_vehicle_status_flags_sub.updated()) {
		vehicle_status_flags_s vehicle_status_flags;

		if (_vehicle_status_flags_sub.copy(&vehicle_status_flags)) {

			// do nothing during regular sensor calibration
			_system_calibrating = vehicle_status_flags.condition_calibration_enabled;
			_system_sensors_initialized = vehicle_status_flags.condition_system_sensors_initialized
						      && vehicle_status_flags.condition_system_hotplug_timeout;
		}
	}

	if (_system_calibrating || !_system_sensors_initialized) {
		return;
	}

	perf_begin(_cycle_perf);

	Vector3f angular_velocity{};

	{
		// Assume a constant angular velocity during two mag samples
		vehicle_angular_velocity_s vehicle_angular_velocity;

		if (_vehicle_angular_velocity_sub.copy(&vehicle_angular_velocity)) {
			angular_velocity = Vector3f{vehicle_angular_velocity.xyz};
		}
	}

	for (int mag_index = 0; mag_index < MAX_SENSOR_COUNT; mag_index++) {
		sensor_mag_s sensor_mag;

		while (_sensor_mag_subs[mag_index].update(&sensor_mag)) {

			// apply existing mag calibration
			_calibration[mag_index].set_device_id(sensor_mag.device_id, sensor_mag.is_external);
			const Vector3f raw_mag{sensor_mag.x, sensor_mag.y, sensor_mag.z};
			const Vector3f mag_calibrated = _calibration[mag_index].Correct(raw_mag);

			float dt = (sensor_mag.timestamp_sample - _timestamp_last_update[mag_index]) * 1e-6f;
			_timestamp_last_update[mag_index] = sensor_mag.timestamp_sample;

			if (dt < 0.001f || dt > 0.2f) {
				_reset_field_estimator[mag_index] = true;
			}

			if (_reset_field_estimator[mag_index]) {
				// reset
				_bias_estimator[mag_index].setBias(Vector3f{});
				_bias_estimator[mag_index].setField(mag_calibrated);

				_reset_field_estimator[mag_index] = false;
				_valid[mag_index] = false;

			} else {
				const Vector3f bias_prev = _bias_estimator[mag_index].getBias();

				_bias_estimator[mag_index].updateEstimate(angular_velocity, mag_calibrated, dt);

				const Vector3f &bias = _bias_estimator[mag_index].getBias();
				const Vector3f bias_rate = (bias - bias_prev) / dt;

				Vector3f fitness;
				fitness(0) = fabsf(angular_velocity(0)) / fmaxf(fabsf(bias_rate(1)) + fabsf(bias_rate(2)), 0.02f);
				fitness(1) = fabsf(angular_velocity(1)) / fmaxf(fabsf(bias_rate(0)) + fabsf(bias_rate(2)), 0.02f);
				fitness(2) = fabsf(angular_velocity(2)) / fmaxf(fabsf(bias_rate(0)) + fabsf(bias_rate(1)), 0.02f);

				if (!PX4_ISFINITE(bias(0)) || !PX4_ISFINITE(bias(1)) || !PX4_ISFINITE(bias(2)) || bias.longerThan(5.f)) {
					_reset_field_estimator[mag_index] = true;
					_valid[mag_index] = false;

				} else {
					const bool bias_significant = bias.longerThan(0.04f);
					const bool has_converged = fitness(0) > 20.f || fitness(1) > 20.f || fitness(2) > 20.f;

					if (bias_significant && has_converged) {
						_valid[mag_index] = true;
					}
				}
			}
		}
	}

	publishMagBiasEstimate();

	perf_end(_cycle_perf);
}

void MagBiasEstimator::publishMagBiasEstimate()
{
	magnetometer_bias_estimate_s mag_bias_est{};

	for (int mag_index = 0; mag_index < MAX_SENSOR_COUNT; mag_index++) {
		const Vector3f &bias = _bias_estimator[mag_index].getBias();

		mag_bias_est.timestamp = hrt_absolute_time();
		mag_bias_est.bias_x[mag_index] = bias(0);
		mag_bias_est.bias_y[mag_index] = bias(1);
		mag_bias_est.bias_z[mag_index] = bias(2);
		mag_bias_est.valid[mag_index] = _valid[mag_index];
	}


	_magnetometer_bias_estimate_pub.publish(mag_bias_est);
}

int MagBiasEstimator::print_status()
{
	for (int mag_index = 0; mag_index < MAX_SENSOR_COUNT; mag_index++) {
		if (_calibration[mag_index].device_id() != 0) {

			_calibration[mag_index].PrintStatus();

			const Vector3f &bias = _bias_estimator[mag_index].getBias();

			PX4_INFO("%d (%" PRIu32 ") bias: [% 05.3f % 05.3f % 05.3f]",
				 mag_index, _calibration[mag_index].device_id(),
				 (double)bias(0),
				 (double)bias(1),
				 (double)bias(2));
		}
	}

	return 0;
}

int MagBiasEstimator::print_usage(const char *reason)
{
	if (reason) {
		PX4_ERR("%s\n", reason);
	}

	PRINT_MODULE_DESCRIPTION(
		R"DESCR_STR(
### Description
Online magnetometer bias estimator.
)DESCR_STR");

	PRINT_MODULE_USAGE_NAME("mag_bias_estimator", "system");
	PRINT_MODULE_USAGE_COMMAND_DESCR("start", "Start the background task");
	PRINT_MODULE_USAGE_DEFAULT_COMMANDS();
	return 0;
}

extern "C" __EXPORT int mag_bias_estimator_main(int argc, char *argv[])
{
	return MagBiasEstimator::main(argc, argv);
}

} // namespace load_mon