Position estimation of lap joints for seam tracking applications at mm-wave frequencies

In this paper, we present the results of using a frequency-stepped continuous-wave radar system to estimate the position of overlapping and highly electrically conductive plates. We especially focus on polarimetric scattering effects caused by the step of a lap joint, which is a common welding geometry. To model the step´s contribution to the overall scattered signal, we use a two-dimensional combined field integral equation approach. For demonstrating its practical applicability, the implemented scattering model is verified by measurements. To emphasize its improvements, the outcomes of the model are compared to a commonly used point scattering model. Finally, the numerical signal is utilized to precisely estimate the position of the lap joint.