Robust Electromagnetic Pose Estimation for Robotic Applications

A wireless electromagnetic field-based sensor system is proposed, which enables the tracking of moving objects, e.g., drones. The gathered up to 6-degrees of freedom information is complementary to existing sensing principles, e.g., global positioning system (GPS) or vision-based systems. In addition, it can be used for stand-alone navigation or noninvasive localization of medical devices inside the human body. The sensor system is comprised of an exciter and a sensor. The exciter can be mounted on a moving robot and generates an electromagnetic field. The field is measured by the sensor, and subsequently, the pose of the exciter with respect to the sensors' pose is estimated. Conductive objects in the vicinity of the sensor alter the measured magnetic field due to the induced eddy currents. In general, unmanned aerial vehicles or wheeled robots mainly consist of conductive materials, which cause a significant estimation error. This article introduces an interference-aware electromagnetic near-field-based pose estimation approach. Specifically, the change in the magnetic field due to close conductive and ferromagnetic objects is modeled. Iterative numerical solutions of Maxwell's equations, based on, e.g., finite-element method, are avoided. Instead, an analytic expression of the change in the magnetic field due to present eddy currents is given. The advantages of the proposed concept for model-based low-complexity pose estimation concepts are shown using an extended Kalman filter. It is observed that the tracking performance using the introduced model outperforms the traditional model in eddy current scenarios significantly.