unit test: check that the accel bias is only learned when observable (#827)

test/sensor_simulator/ekf_wrapper.cpp

@@ -200,3 +200,8 @@ int EkfWrapper::getQuaternionResetCounter() const
 	_ekf->get_quat_reset(tmp, &counter);
 	return static_cast<int>(counter);
 }
+
+matrix::Vector3f EkfWrapper::getDeltaVelBiasVariance() const
+{
+	return _ekf->covariances_diagonal().slice<3, 1>(13,0);
+}

test/sensor_simulator/ekf_wrapper.h

@@ -94,6 +94,8 @@ public:
 	matrix::Vector<float, 4> getQuaternionVariance() const;
 	int getQuaternionResetCounter() const;
 
+	matrix::Vector3f getDeltaVelBiasVariance() const;
+
 private:
 	std::shared_ptr<Ekf> _ekf;