Autonomous unmanned aerial vehicle (UAV) landing on a moving unmanned ground vehicle (UGV) remains a challenge as it is difficult for the UAV to track the real-time state of the UGV and adjust its landing policy accordingly. This paper proposes a learning framework for a quadrotor UAV to land on a moving UGV without knowing its motion dynamics. Specifically, the learning framework consists of two main systems: a Landing Vision System (LVS) using deep learning and a Landing Control System (LCS) using deep reinforcement learning. The LVS enables the UAV to recognize and localize the UGV in real time to estimate the relative position and velocity between them. Besides, the location of the UGV is tracked in the field of view of the UAV using consecutive images, alleviating the tracking failure problem. We propose a Memory Consolidated TD3 (MCTD3) algorithm to generate optimal policies to enable precise tracking and landing control of the UAV. In addition, we propose an adaptive COACH (ACOACH) algorithm that allows human intervention in the action space of the UAV to speed up the training process. We demonstrate the effectiveness of the proposed method in both simulation and real-world experiments.

Collaborative autonomous landing of a quadrotor Unmanned Aerial Vehicle (UAV) on a moving Unmanned Ground Vehicle (UGV) presents challenges due to the need for accurate real-time tracking of the UGV and the adjustment for the landing policy. To address this challenge, we propose a progressive learning framework for generating an optimal landing policy based on vision without the need of communication between the UAV and the UGV. First, we propose the Landing Vision System (LVS) to offer rapid localization and pose estimation of the UGV. Then, we design an Automatic Curriculum Learning (ACL) approach to learn the landing tasks under different conditions of UGV motions and wind interference. Specifically, we introduce a neural network-based difficulty discriminator to schedule the landing tasks according to their levels of difficulty. Our method achieves a higher landing success rate and accuracy compared with the state-of-the-art TD3 reinforcement learning algorithm.

Tracking a moving unmanned ground vehicle (UGV) with an autonomous Unmanned Aerial Vehicle (UAV) is challenging, particularly in GNSS-denied indoor environments where reacquiring the UGV after losing track poses a significant obstacle. This paper presents a novel learning framework designed to address these challenges, enabling a quadrotor UAV to effectively chase a moving UGV and regain tracking in an indoor environment. The proposed framework encompasses two primary components: the Track-HCL and the Tracking Vision System (TVS). The TVS leverages a lightweight tracker to offer real-time recognition and localization of the UGV. Additionally, the Chronological Ghosting (CG) method is employed to describe the UGV’s motion trend within a single frame. The Track-HCL component introduces a hybrid curriculum strategy to guide policy learning for the Deep Reinforcement Learning (DRL) agent. The Track-HCL enables the agent to learn the tracking policy conducive to target chasing and proficient reacquisition. We demonstrate the effectiveness of the proposed method in both simulation and field experiments.