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/**
 * @file zero_innovation_heading_update.cpp
 * Control function for ekf heading update when at rest or no other heading source available
 */

#include "ekf.h"

void Ekf::controlZeroInnovationHeadingUpdate()
{
	const bool yaw_aiding = _control_status.flags.mag_hdg || _control_status.flags.mag_3D
				|| _control_status.flags.ev_yaw || _control_status.flags.gps_yaw;

	// fuse zero innovation at a limited rate if the yaw variance is too large
	if(!yaw_aiding
	    && isTimedOut(_time_last_heading_fuse, (uint64_t)200'000)) {

		// Use an observation variance larger than usual but small enough
		// to constrain the yaw variance just below the threshold
		const float obs_var = _control_status.flags.tilt_align ? 0.25f : 0.001f;

		estimator_aid_source1d_s aid_src_status{};
		aid_src_status.observation = getEulerYaw(_state.quat_nominal);
		aid_src_status.observation_variance = obs_var;
		aid_src_status.innovation = 0.f;

		VectorState H_YAW;

		computeYawInnovVarAndH(obs_var, aid_src_status.innovation_variance, H_YAW);

		if (!_control_status.flags.tilt_align || (aid_src_status.innovation_variance - obs_var) > sq(_params.mag_heading_noise)) {
			// The yaw variance is too large, fuse fake measurement
			fuseYaw(aid_src_status, H_YAW);
		}
	}
}