PolarVisor: Clutter-free, Electronics-free Fiducial Markers for mmWave Radars Printed on Paper

In this paper, we design and fabricate cost-effective, electronics-free millimeter-wave (mmWave) fiducial markers that support clutter-free detection on radars. Fiducial markers are widely used in camera-based systems to provide spatial information in robotic navigation applications. QR-code-like fiducial markers can be readily printed on paper - low-cost, easy to produce, and electronics-free. Yet, an analogous mmWave solution is yet to appear, which stems from the unique challenge in the mmWave context: its vulnerability to clutter. Existing solutions either trade hardware simplicity for clutter resilience or stay simple but remain vulnerable to environmental multipath. This paper seeks to solve this dilemma.