Speckle shift tracking sensor for high accuracy 6-DoF pose measurements

Abstract Six-degree-of-freedom (6-DoF) pose measurements, encompassing simultaneous position ( XYZ ) and orientation ( UVW ) tracking, are crucial in precision manufacturing. Despite robots offering high repeatability, their single-shot accuracy diminishes under heavy loads, posing challenges in various applications. This paper introduces a 6-DoF sensor concept based on speckle shift measurements, which leverages the movement of speckle patterns generated by light scattering from an optically rough surface. By capturing speckle shifts at multiple image sensor positions, the sensor can distinguish between translations and rotations, enabling precise pose measurements. A precision below 2 μm for translations and 7 μrad for rotations, with trueness of 1.5 μm and 5.2 μrad, respectively, are experimentally shown for random 6-DoF movements. The speckle shift sensor is compared to established alternatives.