A State-of-the-Art Analysis of Obstacle Avoidance Methods from the Perspective of an Agricultural Sprayer UAV’s Operation Scenario

Abstract

Over the last decade, Unmanned Aerial Vehicles (UAVs), also known as drones, have been broadly utilized in various agricultural fields, such as crop management, crop monitoring, seed sowing, and pesticide spraying. Nonetheless, autonomy is still a crucial limitation faced by the Internet of Things (IoT) UAV systems, especially when used as sprayer UAVs, where data needs to be captured and preprocessed for robust real-time obstacle detection and collision avoidance. Moreover, because of the objective and operational difference between general UAVs and sprayer UAVs, not every obstacle detection and collision avoidance method will be sufficient for sprayer UAVs. In this regard, this article seeks to review the most relevant developments on all correlated branches of the obstacle avoidance scenarios for agricultural sprayer UAVs, including a UAV sprayer’s structural details. Furthermore, the most relevant open challenges for current UAV sprayer solutions are enumerated, thus paving the way for future researchers to define a roadmap for devising new-generation, affordable autonomous sprayer UAV solutions. Agricultural UAV sprayers require data-intensive algorithms for the processing of the images acquired, and expertise in the field of autonomous flight is usually needed. The present study concludes that UAV sprayers are still facing obstacle detection challenges due to their dynamic operating and loading conditions.

Multiobjective Optimization Method for the Diversion Scheme of Lean Concrete Overtopped Cofferdam under Multiconstraint Conditions

“…Comparing the effective construction time with the actual construction time, the reliability of the on-time completion of the lean cemented cofferdam can be obtained, as shown in formula (28). The project completion reliability should meet the design requirements, as shown in formula (29).…”

Stability Analysis of a Sprayer UAV with a Liquid Tank with Different Outer Shapes and Inner Structures

“…Maintaining an effective droplet deposition, safety rules, and flight stability during a sprayer UAV's operation is a key part of precision agriculture [15,16]. In farmland, uncontrollable weather conditions, such as sudden wind direction changes, and complicated obstacles, such as plant protection nets, power lines, towers, lighting structures, and buildings, are the most common difficulties for sprayer UAVs [17]. Facing and tackling those difficulties, such as sudden flight path changes, is a common phenomenon for this kind of liquid-carrying UAV particularly during the flight operation of an agricultural UAV in the field.…”

“…The automatic avoidance performance was performed using the K++ flight controller and an agricultural sprayer UAV [19]. Currently, there is a large number of studies on droplet depositions [13], control effects after spraying [14], spray-system designs [15], and remote-sensing designs [16,17], etc. However, very few studies have been done about slosh control inside the tank of a sprayer UAV.…”

Simulasi Kestabilan Prototype Uav-Sprayer Berbasis Quadcopter Terhadap Penambahan Sekat Pada Penampung Cairan

“…Oleh karena itu pengendali dalam hal ini adalah pilot harus mampu menghadapi dan mengatasi kesulitan-kesulitan tersebut. Perubahan lintasan yang tiba-tiba dan menstabilkan pengoperasian penyemprot UAV menjadi lebih sulit karena tumpahan cairan tangki yang terpasang, gerakan cairan secara tiba tiba ini akan menghasilkan efek kejutan terus menerus untuk UAV [18]. Pada Gambar 1, gangguan dari efek slosh ditampilkan.…”