Enhancing the energy efficiency of drones, particularly in extending the flight lifetime, has emerged as a crucial area. Position reconfiguration has been explored as a mechanism to achieve this goal for swarm drones. Building on this concept, we investigate how position reconfiguration can be applied within urban wind environments to further extend the lifetime of drone swarms. Despite its potential, efficiently implementing position reconfiguration remains challenging. To address it, we propose an efficient position reconfiguration scheme that reduces the energy consumption imbalance of the swarm and prolongs the lifetime. The scheme includes: (1) a MIP (mixed integer programming)-based optimization method. (2) an approximation algorithm that runs in pseudo-polynomial time and without the need for an optimization solver. The scheme provides a complete position reconfiguration solution that determines (i) the number of position reconfiguration; (ii) when to perform reconfiguration; (iii) who to change positions. Simulation and experimental results demonstrate the effectiveness of our scheme. Note to Practitioners—In urban environments, the significant variation in wind speeds leads to an energy imbalance among swarm drones performing tasks. This paper addresses the practical issue of extending the lifetime of drones in such environments by optimizing position reconfiguration. Specifically, drones operating in high wind speed areas require more energy to maintain hovering, resulting in faster battery depletion. By allowing drones with more remaining energy to exchange positions with those experiencing higher energy consumption, the overall energy usage can be balanced, thus extending the mission duration. We propose an energy-efficient scheduling scheme to determine when and which drones should reconfigure their positions. The scheme strikes a balance between the benefits of reconfiguration and the associated energy costs, preventing unnecessary movement that could waste energy while ensuring drones do not deplete their batteries prematurely. This solution is particularly suited for drone swarms operating in urban environments. Future research could further explore the integration of this scheme into real-time drone fleet management systems.

In agile quadrotor flight, accurately modeling the varying aerodynamic drag forces encountered at different speeds is critical. These drag forces significantly impact the performance and maneuverability of the UAV, especially during high-speed maneuvers. Traditional control models based on first principles struggle to capture these dynamics due to the complexity and variability of aerodynamic effects, which are challenging to model accurately. To address these challenges, this study proposes a meta-learning-based control strategy for accurately modeling quadrotor dynamics under varying speeds, treating each velocity condition as an independent learning task with a specifically trained neural network to ensure precise dynamic predictions. The meta-learning framework rapidly generates task-specific parameters adapted to speed variations by solving an optimization problem and employs an online incremental learning strategy to integrate real-time data for continuous model updates, enhancing system robustness. Regularization is introduced to prevent overfitting and improve generalizability. The integration of the meta-learned model into Model Predictive Contouring Control (MPCC) allows the system to achieve optimal control across different velocity levels, ensuring efficient and accurate flight control even during sharp turns and high-speed maneuvers. Extensive simulations and real-world experiments confirm that the proposed algorithm maintains a high level of control precision despite the nonlinear effects of rapid speed changes, complex flight trajectories and wind disturbances. The results highlight the advantages of combining meta-learning with adaptive control strategies, providing a robust framework for quadrotors operating in diverse and dynamic environments.

The article presents an air-assisted ground robotic autonomous exploration framework, which leverages the high mobility and wide aerial perspective of unmanned aerial vehicles (UAVs) to assist unmanned ground vehicles (UGVs) in detailed exploration, enhancing exploration efficiency and improving the quality of point cloud collection in regions of interest in large-scale, unknown environments. In this framework, the UAV, equipped with an onboard RGB camera, rapidly surveys large unknown areas and generates a bird's eye view (BEV) to identify critical zones for UGV exploration. With prior information about the unexplored area's outline from the real-time shared BEV, the UGV can carry out more efficient and informed exploration from a global perspective. To maximize the utility of this prior information and optimize point cloud collection, a hierarchical exploration strategy and an attention mechanism are incorporated to guide the UGV's focus toward areas requiring detailed mapping, rather than broad, featureless regions. Real-world experiments validate the effectiveness of the framework, demonstrating significant improvements in exploration efficiency and point cloud collection compared to state-of-the-art methods. The results further show that even with a coarse BEV, the UGV's exploration efficiency is greatly enhanced.

Aerial manipulation has received increasing research interest with wide applications of drones. To perform specific tasks, robotic arms with various mechanical structures will be mounted on the drone. It results in sudden disturbances to the aerial manipulator when switching the robotic arm or interacting with the environment. Hence, it is challenging to design a generic and robust control strategy adapted to various robotic arms when achieving multi-task aerial manipulation. In this paper, we present a learning-based control algorithm that allows online trajectory optimization and tracking to accomplish various aerial interaction tasks without manual adjustment. The proposed energy-saved trajectory planning approach integrates coupled dynamics model with a single rigid body to generate the energy-efficient trajectory for the aerial manipulator. Addressing the challenges of precise control when performing aerial manipulation tasks, this paper presents a controller based on deep neural networks that classifies and learns accurate forces and moments caused by different robotic arms and interactions. Moreover, the forces arising from robotic arm motions are delicately used as part of the drone’s power to save energy. Extensive real-world experiments demonstrate that the proposed method can adapt to various robotic arms and interactions when performing multi-task aerial manipulation.

Autonomous exploration plays a crucial role in robotics applications like rescue and scene reconstruction. This work addresses the challenges of autonomous exploration in intricate unknown environments by presenting a novel UAV autonomous exploration method based on a new concept of the view-region. Our proposed approach leverages the view-region to replace the conventional viewpoint generation and selection process, streamlining the planning process for exploration. Simultaneously, we model the problem of maximizing frontier coverage within the field of view during exploration, and jointly optimize it with the exploration path optimization problem. This approach ensures exploration path safety and effectiveness while being aggressive. Additionally, a gimbal is incorporated beneath the camera, with an associated optimization problem designed to minimize UAV self-rotation and enhance exploration efficiency. Simulations and real-world experiments demonstrate that the proposed method outperforms existing state-of-the-art methods in terms of runtime and distance traveled.

This paper presents a safe learning control strategy aimed at ensuring the accurate tracking of multiple unmanned aerial vehicles (UAVs) along their predetermined trajectories while also guaranteeing safety under uncertain environments such as trajectory conflict, airflow interference between UAVs, and external disturbances. The proposed control framework employs a high-level learning-based feedback linearization control combined with model predictive control (LB-FBL-MPC), coupled with a low-level safety barrier certificates and control Lyapunov function-based quadratic programs (SC), for nonlinear multiple-UAV systems. The high-level LB-FBL-MPC uses incremental Gaussian processes (IGPs) to learn uncertain disturbances online, and feedback linearization is applied to approximate the linear system. The MPC optimizes the reference trajectory based on the linearized dynamical model to enhance the adaptivity of the system. Furthermore, the low-level SC guarantees the safety and asymptotic stability of the multi-UAV system by using the prediction distribution of the IGPs. Ablation and benchmark comparison experiments demonstrate the efficacy of the proposed tracking control strategy.Note to Practitioners—Controlling multiple unmanned systems to achieve precision and safety in complex environmental disturbances is a challenge. Existing machine learning-based control frameworks are mostly limited by low learning efficiency and poor interpretability, making it difficult to deploy them in practical robot systems. This article introduces a machine learning and control theory combined framework for the safe control of multiple unmanned aerial vehicles. On the one hand, the framework enables UAVs to quickly learn uncertain environmental disturbances without the need for any pre-collected data. The use of a linearized system model greatly reduces computation time and provides a new approach for practical engineering deployment. On the other hand, by designing separate quadratic programming, we prove the stability and safety of the system. Extensive experiments demonstrate that the designed control strategy significantly improves system control performance while ensuring system safety.

This paper investigates the uplink secure transmission in an intelligent reflecting surface (IRS) aided Cell-Free Multiple Input Multiple Output network. To maximize the minimum secrecy rate (SR) among legitimate users, we jointly optimize the uplink power control vector and the passive beamforming vector at IRS with consideration of resource allocation fairness. We propose an alternating optimization based SR max-min fairness algorithm to solve the non-convex problem. Based on semidefinite relaxation, the sub-problem of phase optimization at IRS is solved. Geometric programming is utilized to handle the optimization of power control with the assist of condensation method. Simulation results verify that the proposed algorithm can converge to obtain the solution. The minimum SR of the proposed scheme is increased by 14% compared with random phase scheme and the max-min fairness among users is realized.

Control of an aerial manipulator is challenging due to the decentralized dynamics of the aerial vehicle and the robotic arm. It is generally complex to adjust the controller of the aerial manipulator when replacing a different robotic arm. This paper presents a flexible control scheme for a quadrotor-based aerial manipulator equipped with a replaceable robotic arm. To analyze the dynamic characteristics during grasping, the model of the aerial manipulator is decentralized including the models of a quadrotor and the centroid of an n-DOF robotic arm. The interaction effect of a moving robotic arm on the quadrotor is considered by analyzing the varying centroid of the robotic arm. Based on the modeling of the aerial manipulator, a control scheme integrating a linear model predictive control (LMPC) and a feedforward controller is presented to accurately control the motion of the aerial platform. The LMPC controls the aerial vehicle to follow the desired trajectory, and a feedforward controller keeps the aerial platform hovering stably during grasping. Practical experiments with two different robotic arms are performed. Experimental results show that the proposed modeling and control scheme provides a flexible and effective approach for an aerial manipulator with a replaceable robotic arm.