Autonomous 3D exploration with Unmanned Aerial Vehicle (UAV) is increasingly prevalent for environment monitoring without human intervention. In this study, we present a systematic solution towards efficient UAV exploration in 3D environments. Innovatively, a road map is incrementally built and maintained along with the exploration process, which explicitly exhibits the topological structure of the 3D environment. By simplifying the environment, the road map can efficiently provide the information gain and the cost-to-go for a candidate region to be explored, which are two quantities for Next-Best-View (NBV) evaluation, thus prompting the efficiency for NBV determination. In addition, with reference to the global plan queried on the road map, we propose a local planner based on the potential field method that drives the robot to the information-rich area during the navigation process, which further improves the exploration efficiency. The proposed framework and its composed modules are verified in various 3D environments, which exhibits their distinctive features in NBV selection and better performance in improving the exploration efficiency than other methods.

Human-aware path planner is essential for achieving harmonious coexistence between humans and robots in highly dynamic environments. In this paper, we propose an integrated framework to find the optimal path in the complex environment with considering collision risk, social norms, and crowded areas. In the proposed framework, a general dynamic group model (g-space) based on the Gaussian Mixed Model (GMM) is proposed as the social norms of dynamic groups, which not only considers the factors of humans (e.g., pose, quantity, distribution, psychology) but also establishes the proximity and human interacting constraints of dynamic groups. An integrated Collision Risk and Human Space (CR&HS) model is applied to achieve human-acceptable behaviors, in which both collision avoidance, human comfort, and interference-free constraints have been involved. Moreover, an Improved Virtual Doppler Method (IVDM) has been used to realize safety navigation to avoid the robot falling into the crowded area. Finally, the proposed framework has been utilized with the sampling-based rapidly-exploring random tree. Experimental results demonstrate that the proposed method can generate the optimal human-aware collision-free path in complex environments.

Point cloud is a discrete and unordered expression of 3D data. A lot of methods have been proposed to solve the problem in 3D object classification and scene recognition. To handle the huge amount of unordered point cloud, down-sampling before processing is needed. The shortage of existing sampling methods is the lack of geometry information consideration, which is essential for point cloud classification and segmentation tasks. Our method is mainly motivated by the observation that points with a high curvature variation can depict the outlines of objects. Thus, we propose a curvature variation based sampling method for point cloud classification and segmentation tasks. We aim to sample points with high curvature variations, which are considered to be more suitable for classification and segmentation tasks than the traditional sampling method. We combine the proposed sampling algorithm with the existing sampling method for multiple information fusion, and a higher accuracy and mean IoU can be achieved. The experimental results verify the advantage of considering curvature variation in classification and segmentation tasks.

Robot person following (RPF) is a crucial capability in human-robot interaction (HRI) applications, allowing a robot to persistently follow a designated person. In practical RPF scenarios, the person can often be occluded by other objects or people. Consequently, it is necessary to re-identify the person when he/she reappears within the robot's field of view. Previous person re-identification (ReID) approaches to person following rely on a fixed feature extractor. Such an approach often fails to generalize to different viewpoints and lighting conditions in practical RPF environments. In other words, it suffers from the so-called domain shift problem where it cannot re-identify the person when his re-appearance is out of the domain modeled by the fixed feature extractor. To mitigate this problem, we propose a ReID framework for RPF where we use a feature extractor that is optimized online with both short-term and long-term experiences (i.e., recently and previously observed samples during RPF) using the online continual learning (OCL) framework. The long-term experiences are maintained by a memory manager to enable OCL to update the feature extractor. Our experiments demonstrate that even in the presence of severe appearance changes and distractions from visually similar people, the proposed method can still re-identify the person more accurately than the state-of-the-art methods.

Although the LiDAR SLAM technique has been already widely deployed on various robots, it may still suffers from degeneracy caused by inadequate constraints in scenes with sparse geometric features. If the degeneracy is not detected and properly processed, the accuracy of localization and mapping will significantly decrease. In this letter, we propose the P2d-DO method, which consists of a point-to-distribution degeneracy detection algorithm and a point cloud-weighted degeneracy optimization algorithm, to relieve the negative impact of degeneracy. The degeneracy detection algorithm outputs factors that characterize the degeneracy state by observing changes in the distribution probabilities within a local region. Factors reflecting the confidence of the point clouds are then fed to the degeneracy optimization algorithm, enabling the system to prioritize reliable point clouds by assigning larger weights during the matching process. Comprehensive experiments validate the effectiveness of our method, demonstrating significant improvements in both degeneracy detection and pose estimation in terms of accuracy and robustness.

Autonomous pedestrian-aware navigation in shared human-robot environments is a challenging problem. Here we consider a common situation in which a large crowd of pedestrians moves together in a limited space. Traditional planners struggle to find collision-free paths in such situations since the free space is limited and always changing. To solve this problem, we proposed a flow map-based RRT* method (FM-RRT*) containing a velocity layer and a minimally-intrusive layer. The proposed method models the velocity of the pedestrian flow and the area where the robot is less invasive to pedestrians. Furthermore, we propose an adaptive bias sampling, which drives the robot considering relative velocity, or minimal intrusion, according to the pedestrian flow. The evaluation is conducted in the Crowdbot Challenge simulator. The results show that our method can find a feasible path considering collision risk while simultaneously avoiding intrusive human movement.