This paper deals with the current technology status and technology development direction on shape shifting drone. A shape shifting drone is defined as a drone for which its shape and/or function of its platform in flight can be changed by shape shifting technology in order to fulfill a variety of missions effectively in harsh mission environment. A shape shifting drone can be classified as a rotary-wing based, a fixed-wing based, or a biomimetic based shape shifting drone. This work describes technology trends of domestic and foreign countries. It identifies core technologies and development direction. This work will be useful for planning research and development programs on required technology for the development of shape shifting drone in the future.

Drones are increasingly used in various fields such as agriculture, logistics, and disaster response due to their agility and versatility. In indoor plant factories, small drones are used to monitor crop conditions and collect environmental data. However, small drones require frequent recharging due to their limited battery capacity, making autonomous charging systems essential for uninterrupted operation of drones. This study proposes an autonomous charging station designed for small drones in indoor plant factories. The system employs a wired charging mechanism to enhance charging efficiency, and a 3-degree-of-freedom (DOF) pose alignment system, utilizing an XY plotter and turntable, to correct drone landing errors. The alignment system ensures that drones, landing with random positions and orientations, are automatically adjusted to the correct position for charging. Experiments demonstrated that the charging station successfully aligned and charged drones with a 93% success rate on the first attempt. Even in cases of failure, the system automatically retried until a 100% success rate was achieved. This autonomous drone charging system has the potential to significantly enhance operational efficiency in indoor plant factories and can be adapted for various drone models in future applications.

This study deals with the structural integrity of a co-axial octocopter cargo drone. Most unstable states in progress of various flight missions of the cargo drone are considered to be derived from take-off and landing operations. In order to evaluate the structural integrity of these states, three-dimensional FE (finite element) simulation using whole frame assembled with structural members and components is performed, and then the effective stress level and deflection degree are investigated. Also, topology optimization is adopted to improve the locally concentrated stress and large deflection around front and rear sections of the motor-support side member. From topology optimization, it is ensured that the shape and location of plate support have to be modified for improving the stress level and the deflection degree. Based on the optimized and modified feature, FE simulation is re-performed. Consequently, it is confirmed that the effective stress and the deflection are reduced to about 26.67% and 19.15% around the side member, respectively.

Improving battery performance is crucial for increasing drone flight time. However, developing individual parts can also enhance mission performance and extend operating time. By attaching a drone to a wall instead of hovering in the air, the operating time and range of task performance can be extended. This study focuses on the adhesion force of a modular permanent magnet wheel leg for wall climbing drones. The wheel leg comprised several spokes without a rim. It could climb obstacles higher than wheel radius and provide a large adhesion area. An equation for the adhesion force of the wheel leg was derived, considering mechanical factors such as drone size, inclination of the ferromagnetic wall, and drone posture. A simple experimental model was created to verify the validity of the adhesive force equation. The effectiveness of the derived equation was confirmed by experimentally measuring the angle of the ferromagnetic wall that losT adhesion according to mechanical factors and comparing it with the derived adhesion force.

Drone is an innovative industry that can combine the application of various technologies in the fourth industrial era, such as big data, artificial intelligence, and ICT. Although the synergy effects of these technologies will be great in various industrial ecosystems, drones are vulnerable to gusts such as "building wind" or "valley wind". Herein, the frequency domain of a mini drone was identified and a model-based disturbance observer (DOBs) was applied to implement the drone robust resistance against gusts. The frequency response of the Parrot Mambo or mini drone was measured with multi-sine excitation and the system dynamic parameters were identified. Based on the identified model, DOBs were designed and applied to the drone’s altitude, position, and yaw control. The effectiveness of the DOBs was verified with a sinusoidal disturbance. With the model-based DOB, 84.5% of the drone altitude responses, 50.7% of x responses, 52.1% of y responses, and 79.7% of yaw responses against sinusoidal disturbances were reduced. Flight responses were measured against wind disturbances with changing speed and direction. With the model-based DOBs, the drone"s altitude decreased by 87.7%, the x position by 53.0%, the y position by 60.6%, and the yaw angle by 56.2%.

In this study, the structural integrity of an engine-generator support structure of hybrid drone is verified through finite element (FE) analysis and experimental investigation. From preliminary experiments, critical failures in four columns of the support structure were observed. Due to the repeated cyclic loads induced by the engine-generator operation, the results of the FE simulation pointed out that fatigue failure is the main cause. To improve the structural integrity, the geometric shape and the material of the structural members are modified and changed, and the safety factor is also reviewed using static structural analysis. The possibility of critical resonance is evaluated through FEM-associated modal analysis and a series of vibration tests. As result, it is confirmed that the re-designed support structure was structurally improved with enough safety margin through FE analysis and experimental investigation, and fatigue life by comparing the predicted value and S-N curve of the material used to the support structure was improved.

Drone stations are increasingly being applied to enhance the mission capabilities of drones. The drone’s station landing occurs in a limited space. A relative position communication signal between the drone and the station is required. Strong, precise control over communication signal interference is required. In this paper, we describe a filter processing method for position signal processing. In consideration of the anchor position and installation angle of the UWB module of the drone station, nine performance test cases were proposed. As a result of the performance test, high position accuracy output was confirmed when considering the result of minimizing signal shading and beam pattern direction with excellent reception sensitivity. A performance test was conducted using the developed drone station, and the landing performance was confirmed with a precision of within 20 cm.

An elevating drone station is very useful when lifting and lowering the battery charging station for safe installation, maintenance, and energy efficiency of a drone operation. When drone station modules rise above the average roof level of neighboring structures they may receive a strong wind force; thus, understanding the physical phenomena of both the structures and fluid is important to understand the structure"s reaction to the wind force. However, most studies in the field of drone stations did not perform a structural safety evaluation under wind loadings. Therefore, in this paper, we carried out a fluid-structure interaction analysis to verify the design of the lifting-and-lowering-type drone station.

The lifting-and-lowering type drone station is very useful when lifting and lowering the battery charging station for safe installation, maintenance, and energy efficiency of drone operation. Therefore, understanding the coupling motion between cable and pulley is important for evaluating characteristics like safety and dynamic stability of the lifting-and-lowering type drone station. Although multibody dynamics (MBD) is widely used for numerically analyzing the dynamic behavior of interconnected bodies, attempts to analyze the coupling motion between cable and pulley have been made only recently, within the last decade. Therefore, this paper attempts to develop the MBD model for the lifting-and-lowering type drone station, including cables, pulleys, and winches using MotionSolve (Altair). The results of the winch torque obtained analytically and numerically were compared to verify the effectiveness of the proposed MBD model.

This paper introduces PongBot, a quadruped robot developed for preparation in the Dronebot Challenge held in Jangseonggun, Jeollanam-Do, South Korea in November 2020. The Dronebot Challenge, hosted by the Army Headquarters, is a competition to demonstrate that drones and robots can be useful for military purposes. In 2020, this competition consisted of a total of 8 events and we participated in the ‘Traveling on rough terrain’ event, which consisted of various terrains, such as, slopes, unpaved roads, and streams. PongBot is a quadruped robot that uses an electric motor and can walk for more than an hour on various terrains. Also, according to the rules of the competition, the robot had a system which could be remotely controlled from a ground control station. In addition, by applying the SLAM algorithm, the robot operator received information about its surrounding environment, thereby deriving records to facilitate the operation. The performance of this robot system and SLAM algorithm was verified through this competition.