Unknown area exploration is a crucial but challenging task for autonomous driving of unmanned ground vehicles (UGV) in unknown off-road environments. However, the exploration efficiency of a single UGV is low due to its limited sensing range. To solve this problem, this paper proposes a risk-inspired aerial active exploration system, which utilizes the flexibility and field of view advantages of Unmanned Aerial Vehicles (UAV) to guide the UGV in unknown off-road environments. Firstly, a fast terrain risk mapping method that can be used for both UAV and UGV is developed. This method efficiently combines quadtree and hash table data structure to enable UAV to analyze large scale terrain point cloud in real time. Based on the risk mapping result, a risk-inspired active exploration method is proposed to actively search a safe reference path for the UGV, which introduces terrain risk information into the process of travel point selection. Finally, the reference path is gradually generated and optimized, so that the UGV can safely and smoothly follow the path to the target location. Compared with single UGV exploration system, our approach reduces the overall path risk by 26.8% in simulated experiments, showing that the proposed system can enhance autonomous driving of the UGV and help it effectively avoid high-risk areas in unknown off-road environments.

Self-supervised depth estimation has attracted much attention due to its ability to improve the 3D perception capabilities of unmanned systems. However, existing unsupervised frameworks rely on the assumption of photometric consistency, which may not hold in challenging environments such as night-time, rainy nights, or snowy winters due to complex lighting and reflections, resulting in inconsistent photometry across different frames for the same pixel. To address this problem, we propose a self-supervised monocular depth estimation unified framework that can handle these complex scenarios, which has the following characteristics: (1) an Illumination Compensation PoseNet (ICP) is designed, which is based on the classic Phong illumination theory and compensates for lighting changes in adjacent frames by estimating per-pixel transformations; (2) a Dual-Axis Transformer (DAT) block is proposed as the backbone network of the depth encoder, which infers the depth of local repeat-texture areas through spatial-channel dual-dimensional global context information of images. Experimental results demonstrate that our approach achieves state-of-the-art depth estimation results in complex environments on the challenging Oxford RobotCar dataset.

All-day self-supervised monocular depth estimation has strong practical significance for autonomous systems to continuously perceive the 3D information of the world. However, night-time scenes pose challenges of weak texture and violating the brightness consistency assumption due to low illumination and varying lighting, respectively, which easily leads to most existing self-supervised models only being able to handle day-time scenes. To address this problem, we propose a self-supervised monocular depth estimation unified framework that can handle all-day scenarios, which has three features: (1) an Illumination Compensation PoseNet (ICP) is designed, which is based on the classic Phong illumination theory and compensates for lighting changes in adjacent frames by estimating per-pixel transformations; (2) a Dual-Axis Transformer (DAT) block is proposed as the backbone network of the depth encoder, which infers the depth of local low-illumination areas through spatial-channel dual-dimensional global context information of night-time images; (3) a cross-layer Adaptive Fusion Module (AFM) is introduced between multiple DAT blocks, which learns attention weights between different layer features and adaptively fuses cross-layer features using the learned weights, enhancing the complementarity of different layer features. This work was evaluated on multiple datasets, including: RobotCar, Waymo and KITTI datasets, achieving state-of-the-art results in both day-time and night-time scenarios.

An energy-efficient gait planning method is proposed by imitating natural human walking in this paper. This method uses a 3D Linear Inverted Pendulum Model (LIPM) to improve the walking efficiency for the biped robot, which utilizes the allowable Zero Moment Point (ZMP) regions and slight adjustment of the Center of Mass (COM). The novel gait parameters optimization (NGPO) algorithm is proposed to obtain effective gait parameters that can synthesize optimal gait for minimizing energy consumed by the actuators of humanoid robot joints. Moreover, physical constraints, geometrical constraints, friction force limit and yaw moment limit need to be taken into consideration, ensuring feasible walking trajectory. The validity of the algorithm is verified by simulation, and the gait planning is implemented on XT humanoid robot.