Simultaneous Localization and Mapping (SLAM) allows mobile robots to navigate without external positioning systems or pre-existing maps. Radar is emerging as a valuable sensing tool, especially in vision-obstructed environments, as it is less affected by particles than lidars or cameras. Modern 4D imaging radars provide three-dimensional geometric information and relative velocity measurements, but they bring challenges, such as a small field of view and sparse, noisy point clouds. Detecting loop closures in SLAM is critical for reducing trajectory drift and maintaining map accuracy. However, the directional nature of 4D radar data makes identifying loop closures, especially from reverse viewpoints, difficult due to limited scan overlap. This article explores using 4D radar for loop closure in SLAM, focusing on similar and opposing viewpoints. We generate submaps for a denser environment representation and use introspective measures to reject false detections in feature-degenerate environments. Our experiments show accurate loop closure detection in geometrically diverse settings for both similar and opposing viewpoints, improving trajectory estimation with up to 82% improvement in ATE and rejecting false positives in self-similar environments.

Existing experience with educational institutions that track student outcomes in relation to the time spent on formative activities has demonstrated a consistent positive correlation with improved student outcomes. This study is centred on Higher Education using data from the asynchronous learning platform Möbius, and produces a data-driven validation of the positive correlation between time spent on formative activities and improved student outcomes in an asynchronous online learning environment, and further builds a basis of insights identified as contributors to successful student outcomes. We identified “distance” in time of first engagement in study before an Exam as an early indicator of success, where we found a moderate positive correlation, whereas there was a weak correlation for the same behavior with respect to Practice Tests and Tests. The behaviors identified in this study raised more opportunities for further study on the nature of student engagement through their learning progression, and other early behavioral indicators for successful student outcomes.