In this paper we address the problem of trajectory following in an unknown environment with an unmanned aerial vehicle (UAV). The main goal is to safely follow the planned trajectory by avoiding ...obstacles. The proposed approach is suitable for aerial vehicles equipped with 2D or 3D sensors, such as LiDARs. We present a novel algorithm based on the conventional Artificial Potential Field (APF) called Augmented Artificial Potential Field (AAPF) that corrects the planned path to avoid obstacles. Our proposed algorithm uses a combination of two attractive forces and both normal and rotational repulsive forces to avoid obstacles and handle local minima problems. The smooth trajectory following achieved with the MPC tracker allows us to quickly change and re-plan the UAV path. Comparative simulation experiments have shown that our approach solves local minima problems in trajectory following and generates more efficient paths to avoid potential collisions with static obstacles compared to our previously developed algorithm for obstacle avoidance. The laboratory experimental evaluation results indicate that the algorithm can be deployed on a real UAV with limited computational power and real-time processing requirements.
The condition of the bridge may deteriorate due to the traffic that passes over it, as well as weather and environmental conditions. To ensure the safety and structural stability of the bridges, ...regular inspections of the bridge elements should be carried out. Recent advances in unmanned aerial vehicles (UAVs) can provide tools for accurate and even autonomous inspection of bridge structures without interrupting normal bridge operations. In this paper, we focus on the determination of the dynamic structural parameters of a suspension bridge. The proposed method is based on the estimation of the natural vibration frequency of the bridge cables using the videos captured by the UAV. We provide a detailed theoretical description of the algorithm and an analysis of the simulation results and the data collected during the experiments in the laboratory and in the real case study. In addition to the vision based method for estimating vibration frequency, we tested the ability of the UAV’s on-board sensors to record structural oscillations when the UAV landed on the surface of the bridge.
•Determination of the dynamic structural parameters of a suspension bridge.•Vision based method for estimating vibration frequency.•Estimation of the oscillation frequency of the bridge cables using the UAV.
There are activities in viticulture and mariculture that require extreme physical endurance from human workers, making them prime candidates for automation and robotization. This paper presents a ...novel, practical, heterogeneous, autonomous robotic system divided into two main parts, each dealing with respective scenarios in viticulture and mariculture. The robotic components and the subsystems that enable collaboration were developed as part of the ongoing HEKTOR project, and each specific scenario is presented. In viticulture, this includes vineyard surveillance, spraying and suckering with an all-terrain mobile manipulator (ATMM) and a lightweight autonomous aerial robot (LAAR) that can be used in very steep vineyards where other mechanization fails. In mariculture, scenarios include coordinated aerial and subsurface monitoring of fish net pens using the LAAR, an autonomous surface vehicle (ASV), and a remotely operated underwater vehicle (ROV). All robotic components communicate and coordinate their actions through the Robot Operating System (ROS). Field tests demonstrate the great capabilities of the HEKTOR system for the fully autonomous execution of very strenuous and hazardous work in viticulture and mariculture, while meeting the necessary conditions for the required quality and quantity of the work performed.
In this paper we address the problem of path planning in an unknown environment with an aerial robot. The main goal is to safely follow the planned trajectory by avoiding obstacles. The proposed ...approach is suitable for aerial vehicles equipped with 3D sensors, such as LiDARs. It performs obstacle avoidance in real time and on an on-board computer. We present a novel algorithm based on the conventional Artifcial Potential Field (APF) that corrects the planned trajectory to avoid obstacles. To this end, our modifed algorithm uses a rotation-based component to avoid local minima. The smooth trajectory following, achieved with the MPC tracker, allows us to quickly change and re-plan the UAV trajectory. Comparative experiments in simulation have shown that our approach solves local minima problems in trajectory planning and generates more effcient paths to avoid potential collisions with static obstacles compared to the original APF method.
The structural integrity of bridges is susceptible to deterioration caused by traffic loads, environmental conditions, and weather phenomena. To maintain the safety and stability of bridges, regular ...inspections of their elements are required. Recent advances in the field of unmanned aerial vehicles (UAVs) provide a viable option for accurate and autonomous inspections of bridge structures without disrupting normal operations. This study focuses on the determination of the dynamic structural parameters of a suspension bridge. The methodology focuses on determining the natural vibration frequency of the bridge cables using UAV imagery. This paper contains a detailed theoretical presentation of the algorithm used, accompanied by a careful analysis of simulation results and empirical data from laboratory experiments and real case studies. In addition to the image processing-based approach for estimating the vibration frequency, the sensors on board the drone are also scrutinized and their effectiveness in detecting structural vibrations after the drone lands on the bridge surface is evaluated.
This paper presents an Unmanned Aerial Vehicle (UAV) platform used for the competition held at the International Conference for Unmanned Aircraft Systems 2022 (ICUAS’22). The envisioned scenario in ...the competition is delivering an extinguishing ball to a fire with a UAV. Driven on that thought, the qualifying round of the competition is organized in a realistic simulation environment. The competitors are required to navigate through a cluttered environment into a free space, where they perform a search for the target and deliver the ball as close as possible to that target. The competition finals were organized as a part of the conference, with the same goal as in the simulation qualifiers. The UAVs used for the competition are prepared and provided by the organizers. A detailed description of the UAV software and hardware is outlined in the paper as a step towards standardizing aerial research platform.
The shortcomings of classical methods for inspection of transport infrastructure objects have led to the development of more efficient, more reliable, faster and cheaper procedures for condition ...assessment and load-bearing capacity and service life estimation of objects. In this context, different autonomous systems developed in the last decade have the most notable role and their development is continuously speeding up. This paper provides a state of the art review of the unmanned aerial vehicles application for structural inspection with a focus on bridges. The paper comprises the following: a review of the current regulations prescribing the types and frequency of inspections; a review of the current classical inspection methods with their advantages and disadvantages; analysis of advantages and disadvantages in application of unmanned aerial vehicles for bridge inspections and a review of the equipment commonly used in their development.
In this paper we address the problem of path planning in an unknown environment with an aerial robot. The main goal is to safely follow the planned trajectory by avoiding obstacles. The proposed ...approach is suitable for aerial vehicles equipped with 3D sensors, such as LiDARs. It performs obstacle avoidance in real time and on an on-board computer. We present a novel algorithm based on the conventional Artificial Potential Field (APF) that corrects the planned trajectory to avoid obstacles. To this end, our modified algorithm uses a rotation-based component to avoid local minima. The smooth trajectory following, achieved with the MPC tracker, allows us to quickly change and re-plan the UAV trajectory. Comparative experiments in simulation have shown that our approach solves local minima problems in trajectory planning and generates more efficient paths to avoid potential collisions with static obstacles compared to the original APF method.
Increased capabilities of modern unmanned aerial vehicles (UAVs) in terms of autonomy and payload operations lead towards development of multi-agent UAV systems. While the multi-UAV systems have a ...great potential in many different scenarios, increasing complexity of missions gave raise to a new set of problems. Some of them include high workload periods of a single operator supervising multiple agents, loss of the situation awareness, increased amount of the data generated by the system and problems in communication channels between the operator and UAVs. All of them could lead to performance degradation in the mission execution or even critical failures of system elements. In general, there are two aspects that help to avoid or at least to decrease mentioned problems - mission planning and human-machine interface (HMI) design. In this paper, we mainly address the mission planning aspect and only briefly present an HMI design that allows simultaneous handling of three UAVs in civil infrastructure data acquisition missions. The proposed interface, among the standard telemetry data, includes data download/upload from/to external services, a trajectory planner and the acquired data representation. The proposed architecture has been tested in a simulation and in a real environment.
This paper presents the overview and preliminary results of the HEKTOR - Heterogeneous Autonomous Robotic System in Viticulture and Mariculture project. HEKTOR is divided into two main parts, each ...dealing with specific scenarios in viticulture and mariculture. The robots used in the project and each specific scenario considered are presented. In viticulture, this includes vineyard surveillance, spraying and bud rubbing using an all-terrain mobile manipulator and unmanned aerial vehicle (UAV). In mariculture, scenarios include coordinated monitoring of fish net cages from below the surface and from the air, using the UAV, an unmanned surface vehicle (USV) and a remotely operated underwater vehicle (ROV).
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