Articoli di riviste: "Landing on a mobile target"

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Kwak, Junyoung, Sangwoong Lee, Junsoo Baek e Baeksuk Chu. "Autonomous UAV Target Tracking and Safe Landing on a Leveling Mobile Platform". International Journal of Precision Engineering and Manufacturing 23, n. 3 (31 gennaio 2022): 305–17. http://dx.doi.org/10.1007/s12541-021-00617-8.

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Wang, Zian, Zheng Gong, Yang Yang, Yongzhen Liu, Pengcheng Cai e Chengxi Zhang. "Guidance Law for Autonomous Takeoff and Landing of Unmanned Helicopter on Mobile Platform Based on Asymmetric Tracking Differentiator". Mathematics 11, n. 1 (24 dicembre 2022): 66. http://dx.doi.org/10.3390/math11010066.

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Abstract (sommario):

For some flight missions, such as autonomous landing on mobile platforms, the demands on indicators such as target-tracking accuracy and so on are relatively high. To achieve this, a guidance system with excellent precision is necessary. An asymmetric tracking differentiator based on a tracking differentiator is proposed to establish the guidance system. On the basis of the proposed asymmetric tracking differentiator, an altitudinal and horizontal helicopter guidance system structure is designed. In this paper, a guidance law is designed in order to meet the accuracy and precision requirements in the autonomous landing and transition process. Apart from that, a plane-motion-guidance law is also designed to realize static and dynamic point tracking, linear route tracking and circular route tracking to improve the trajectory smoothness and accuracy. Finally, simulations of the autonomous landing process on moving platforms, including three stages, namely approaching, tracking and landing, are completed. The application effects and precision of the autonomous landing guidance algorithm under different wave heights and period conditions are analyzed through the obtained simulation curves.

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Sergeev, A. A., A. B. Filimonov e N. B. Filimonov. "Control of Autonomous Landing of UAV of Airplane-Type on the Static and Dynamic Sites with Using of "Flexible" Kinematic Trajectories". Mekhatronika, Avtomatizatsiya, Upravlenie 22, n. 3 (2 marzo 2021): 156–67. http://dx.doi.org/10.17587/mau.22.156-167.

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The final and one of the most important stages of the aircraft-type unmanned aerial vehicles (UAV) flight is landing. In this regard the problem of automating the control by UAV landing in difficult meteorological conditions is becoming increasingly urgent. In some cases for refueling and recharging UAVs it is advisable to use the dynamic mobile landing site (MLS) instead of the traditional stationary landing site (SLS). In the present paper we consider the setting of and solution of the control problem by the terminal landing maneuver of a UAV. It provides its transfer from the current initial state to the target final state along " flexible" kinematic trajectories both on the SLS and on the MLS. To solve the problem of automatic landing of UAV on SLS or MLS the mathematical model of the dynamics of its movement was developed. It’s based on the concept of " flexible" kinematic trajectories with spatial synchronization of controlled movements. The control algorithm by the terminal vertical landing maneuver of UAV on SLS by the method of dynamics inverse problem using the principle of " flexible" kinematic trajectories is developed. And also the control algorithm by the terminal landing maneuver of UAV on MLS by the method of dynamics inverse problems using the principles of " flexible" kinematic trajectories and aiming into the target point was also developed. Computer approbation of the synthesized control algorithms for the landing maneuver of UAV "Aerosonde" under conditions of various wind disturbances was carried out using digital modeling in the Matlab environment.

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Avilés-Viñas, Jaime, Roberto Carrasco-Alvarez, Javier Vázquez-Castillo, Jaime Ortegón-Aguilar, Johan J. Estrada-López, Daniel D. Jensen, Ricardo Peón-Escalante e Alejandro Castillo-Atoche. "An Accurate UAV Ground Landing Station System Based on BLE-RSSI and Maximum Likelihood Target Position Estimation". Applied Sciences 12, n. 13 (30 giugno 2022): 6618. http://dx.doi.org/10.3390/app12136618.

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Earth observation with unmanned aerial vehicles (UAVs) offers an extraordinary opportunity to bridge the gap between field observations and traditional air and space-borne remote sensing. In this regard, ground landing stations (GLS) systems play a central role to increase the time and area coverage of UAV missions. Bluetooth low energy (BLE) technology and the received signal strength indicator (RSSI) techniques have been proposed for target location during UAV landing. However, these RSSI-based techniques present a lack of precision due to the propagation medium characteristics, which leads to UAV position vagueness. In this sense, the development of a novel low-cost GLS system for UAV tracking and landing is proposed. The GLS system has been embodied for the purpose of testing the UAV landing navigation capability. The maximum likelihood estimator (MLE) algorithm is addressed on an embedded microcontroller for the position estimation based on the RSSI acquired from an array of BLE devices. Experimental results demonstrate the feasibility and accuracy of the ground landing station system, achieving average errors of less than 0.04 m with the UAV-MLE target position estimation approach. This 0.04 m distance represents an order of magnitude increase in location precision over other currently available solutions. In many cases, this increased precision can enable more innovative docking mechanisms, less likelihood of mishaps in docking, and also quicker docking. It may also facilitate docking procedures where the docking station is itself moving, which may be the case if the docking unit is a mobile ground rover.

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Yue, ZHU, HE Shuai, DUAN Xuechao e XU Ziqi. "UAV Landing Aid Hexapod Robot based on ArUco Marker and Sparse Optical Flow". Journal of Physics: Conference Series 2281, n. 1 (1 giugno 2022): 012002. http://dx.doi.org/10.1088/1742-6596/2281/1/012002.

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Abstract A UAV (Unmanned Aerial Vehicle) landing robot system based on a six-degree-of-freedom hexapod and computer vision with ArUco marker and sparse optical flow is implemented in this paper. By using binocular camera measuring the real-time position and orientation of UAV, a dynamic target tracking method based on ArUco marker and sparse optical flow is proposed. In this method, the ArUco marker is combined with sparse optical flow to improve the accuracy of target detection and the matching error of binocular stereo matching. The binocular vision system with ArUco marker is used to measure and calculate the relative coordinates of markers in the camera coordinate system. Then the UAV contour fitting is conducted in order to obtain the real-time position and orientation of this mobile target. The effectiveness of the novel UAV landing hexapod robot system based on ArUco marker combined with sparse optical flow is verified through the UAV capture experiment.

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Zhu, Jiangcheng, Jun Zhu e Chao Xu. "A simultaneous trajectory generation method for quadcopter intercepting ground mobile vehicle". International Journal of Advanced Robotic Systems 14, n. 4 (1 luglio 2017): 172988141771770. http://dx.doi.org/10.1177/1729881417717702.

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This article proposes a trajectory generator for quadcopter to intercept moving ground vehicle. For this air–ground interaction problem, we formulate the trajectory generation problem as quadratic dynamic programming in a moving-horizon scheme based on the quadcopter kinematics and observation to ground vehicle. The closed-form solution of quadratic dynamic programming in each iteration enables this algorithm a real-time replanning performance. Thereafter, segmented trajectory rule, inspired from commercial flight landing regular, is implemented to guarantee smoothness in approaching and interception to moving ground target from comparably far origin. Our established algorithm is verified through both simulations and experiments.

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Ibarra Jiménez, Efraín, e Manuel Jiménez-Lizárraga. "Robust tracking-surveillance and landing over a mobile target by quasi-integral-sliding mode and Hopf bifurcation". Journal of the Franklin Institute 359, n. 5 (marzo 2022): 2120–55. http://dx.doi.org/10.1016/j.jfranklin.2021.12.017.

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Kownacki, Cezary. "Artificial Potential Field Based Trajectory Tracking for Quadcopter UAV Moving Targets". Sensors 24, n. 4 (19 febbraio 2024): 1343. http://dx.doi.org/10.3390/s24041343.

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The trajectory or moving-target tracking feature is desirable, because it can be used in various applications where the usefulness of UAVs is already proven. Tracking moving targets can also be applied in scenarios of cooperation between mobile ground-based and flying robots, where mobile ground-based robots could play the role of mobile landing pads. This article presents a novel proposition of an approach to position-tracking problems utilizing artificial potential fields (APF) for quadcopter UAVs, which, in contrast to well-known APF-based path planning methods, is a dynamic problem and must be carried out online while keeping the tracking error as low as possible. Also, a new flight control is proposed, which uses roll, pitch, and yaw angle control based on the velocity vector. This method not only allows the UAV to track a point where the potential function reaches its minimum but also enables the alignment of the course and velocity to the direction and speed given by the velocity vector from the APF. Simulation results present the possibilities of applying the APF method to holonomic UAVs such as quadcopters and show that such UAVs controlled on the basis of an APF behave as non-holonomic UAVs during 90° turns. This allows them and the onboard camera to be oriented toward the tracked target. In simulations, the AR Drone 2.0 model of the Parrot quadcopter is used, which will make it possible to easily verify the method in real flights in future research.

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Choi, Sally H. J., Gary K. Yang, Keith Baxter e Joel Gagnon. "Evaluation of Aortic Zone 2 Proximal Landing Accuracy During Thoracic Endovascular Aortic Repair Following Carotid-Subclavian Revascularization". Vascular and Endovascular Surgery 55, n. 4 (4 febbraio 2021): 355–60. http://dx.doi.org/10.1177/1538574421989851.

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Background: Adequate seal for thoracic endovascular aortic repair (TEVAR) commonly requires landing in zone 2, but can prove to be challenging due to the tortuous and angulated anatomy of the region. Objectives: Our objective was to determine the proximal landing accuracy of zone 2-targeted TEVARs following carotid-subclavian revascularization (CSR) and its impact on clinical outcomes. Methods: Retrospective review of patients that underwent CSR for zone 2 endograft delivery at a tertiary institute between January 2008 and March 2018 was conducted. Technical outcomes were assessed by examining the incidence of intraoperative corrective maneuvers, 1a endoleaks and reinterventions. Distance to target and incidence of LSA stump filling were examined as radiographic markers of landing accuracy. Results: Zone 2-targeted TEVAR with CSR was performed in 53 patients for treatment of dissections (49%), aneurysms (30%) or trauma (21%). Nine (17%) cases required intraoperative corrective procedures: 5 (9%) proximal cuffs due to type 1a endoleak and 4 (8%) left common carotid artery (LCCA) stenting due to inadvertent coverage. Cases performed using higher resolution hybrid fluoroscopy machine compared to mobile C-arm were associated with increased proximal cuff use (OR 8.8; 95% CI 1.2-62.4). Average distance between the proximal edge of the covered graft to LCCA was 8 ± 1 mm and larger distances were not associated with higher rates of 1a endoleak. Twenty-eight (53%) cases of antegrade LSA stump filling were noted on follow-up imaging, but were not associated with higher rates of reinterventions (OR 0.8, 95% CI [0.2-4.6]). Three (6%) patients had a stroke within 30 days and 4 (8%) patients expired within 1 month. Intraoperative corrective maneuvers, post-operative 1a endoleak and reinterventions were not associated with higher rates of stroke or mortality. Conclusion: Using current endografts and imaging modalities, zone 2-targeted TEVARs have suboptimal technical accuracy.

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Accomando, Filippo, Andrea Vitale, Antonello Bonfante, Maurizio Buonanno e Giovanni Florio. "Performance of Two Different Flight Configurations for Drone-Borne Magnetic Data". Sensors 21, n. 17 (26 agosto 2021): 5736. http://dx.doi.org/10.3390/s21175736.

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The compensation of magnetic and electromagnetic interference generated by drones is one of the main problems related to drone-borne magnetometry. The simplest solution is to suspend the magnetometer at a certain distance from the drone. However, this choice may compromise the flight stability or introduce periodic data variations generated by the oscillations of the magnetometer. We studied this problem by conducting two drone-borne magnetic surveys using a prototype system based on a cesium-vapor magnetometer with a 1000 Hz sampling frequency. First, the magnetometer was fixed to the drone landing-sled (at 0.5 m from the rotors), and then it was suspended 3 m below the drone. These two configurations illustrate endmembers of the possible solutions, favoring the stability of the system during flight or the minimization of the mobile platform noise. Drone-generated noise was filtered according to a CWT analysis, and both the spectral characteristics and the modelled source parameters resulted analogously to that of a ground magnetic dataset in the same area, which were here taken as a control dataset. This study demonstrates that careful processing can return high quality drone-borne data using both flight configurations. The optimal flight solution can be chosen depending on the survey target and flight conditions.

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RICHARDSON, ELIZABETH A., MICHEL J. KAISER e GARETH EDWARDS-JONES. "Variation in fishers' attitudes within an inshore fishery: implications for management". Environmental Conservation 32, n. 3 (settembre 2005): 213–25. http://dx.doi.org/10.1017/s0376892905002456.

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Understanding the incentives influencing the attitudes and behaviour of resource users is a crucial input to the design of institutions for resource management. Typically fishers have been expected to exploit resources in an independent profit-maximizing manner, which is in line with common property theory, although these expectations are not always met because fishers' behaviours and attitudes are generally more heterogeneous than previously considered. Attitudinal differences between participants in the inshore commercial fishery of Wales, UK, were investigated. Semi-structured face-to-face interviews were conducted with 161 fishers from the five main sectors, namely mobile gear fishers, crustacean potters, whelk potters, line/net fishers and transient fishers. Unprompted expressions of attitudes and responses to open-ended questions underwent thematic-coding and were analysed with fishers' responses to structured questions. Investigation into whether the incentive to participate in resource stewardship varied between sectors as predicted by common property theory found attitudinal similarities across the sectors, but also certain important differences. Results suggested an attitudinal continuum, with mobile gear fishers and crustacean potters at the two extremes, and intermediate positions occupied by transient fishers, whelk potters and line/net fishers. Mobile gear fishers believed most strongly that their fishery was controlled too tightly and was impacted by other fishers and other anthropogenic influences. Crustacean potters believed most strongly that conservation of stocks was necessary and that minimum landing sizes were not overcautious. The attitudes that characterized each sector were related to the characteristics of the sector and its resource base, and generally concurred with theoretical predictions. In particular, target species' mobility and past sector experiences predicted the inclination of fishers in each sector towards resource stewardship. The observed attitudinal differences implied varying personal discount rates that may affect how respondents respond to and comply with management tools. Furthermore, attitudinal differences among sectors mean that an effective management tool in one sector may be inappropriate or counterproductive in another.

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Lu, Wei, Yuxi Li, Yicai Ji, Chuanjun Tang, Bin Zhou e Guangyou Fang. "Ultra-Wideband MIMO Array for Penetrating Lunar Regolith Structures on the Chang’e-5 Lander". Electronics 10, n. 1 (23 dicembre 2020): 8. http://dx.doi.org/10.3390/electronics10010008.

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The Chang’e-5 lunar exploration mission of China is equipped with a Lunar Regolith Penetrating Radar (LRPR) for measuring the thickness and structures of the lunar regolith in the landing area. Since the LRPR is stationary, an ultra-wideband multiple-input multiple-output (MIMO) array is designed as a replacement for conventional mobile subsurface probing systems. The MIMO array, with 12 antenna elements and a switch matrix, operates in the frequency band from 1.0 to 4.75 GHz. In this work, the design and layout of the antenna elements were optimized with respect to the lander. To this end, the antenna elements were designed as miniaturized Vivaldi antennas with quarter elliptical slots (i.e., quarter elliptical slotted antenna, or QESA). QESAs are significantly small while being able to mitigate the impact of the lander on antenna electrical performances. QESAs also have a wide operating bandwidth, flat gain, and excellent time domain characteristics. In addition, a high-temperature resistant ultra-light radome with high transmissivity is designed to protect the external antenna array. After calibration, the MIMO array is used to detect targets embedded in volcanic ash. The detection depth reaches 2.5 m, and the detection effect is good.

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Molina, P., M. Blázquez, J. Sastre e I. Colomina. "PRECISION ANALYSIS OF POINT-AND-SCALE PHOTOGRAMMETRIC MEASUREMENTS FOR CORRIDOR MAPPING: PRELIMINARY RESULTS". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3/W4 (17 marzo 2016): 85–90. http://dx.doi.org/10.5194/isprs-archives-xl-3-w4-85-2016.

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This paper addresses the key aspects of the sensor orientation and calibration approach within the mapKITE concept for corridor mapping, focusing on the contribution analysis of point-and-scale measurements of kinematic ground control points. MapKITE is a new mobile, simultaneous terrestrial and aerial, geodata acquisition and post-processing method. On one hand, the acquisition system is a tandem composed of a terrestrial mobile mapping system and an unmanned aerial system, the latter equipped with a remote sensing payload, and linked through a 'virtual tether', that is, a real-time waypoint supply from the terrestrial vehicle to the unmanned aircraft. On the other hand, mapKITE entails a method for geodata post-processing (specifically, sensor orientation and calibration) based on the described acquisition paradigm, focusing on few key aspects: the particular geometric relationship of a mapKITE network – the aerial vehicle always observes the terrestrial one as they both move –, precise air and ground trajectory determination – the terrestrial vehicle is regarded as a kinematic ground control point – and new photogrammetric measurements – pointing on and measuring the scale of an optical target on the roof of the terrestrial vehicle – are exploited. <br><br> In this paper, we analyze the performance of aerial image orientation and calibration in mapKITE for corridor mapping, which is the natural application niche of mapKITE, based on the principles and procedures of integrated sensor orientation with the addition of point-and-scale photogrammetric measurements of the kinematic ground control points. To do so, traditional (static ground control points, photogrammetric tie points, aerial control) and new (pointing-and-scaling of kinematic ground control points) measurements have been simulated for mapKITE corridor mapping missions, consisting on takeoff and calibration pattern, single-pass corridor operation potentially performing calibration patterns, and landing and calibration pattern. Our preliminary results show that the exterior orientation, interior orientation and tie points precision estimates are better when using kinematic control with few static ground control, and even with excluding the latter. We conclude then that mapKITE can be a breakthrough on the UAS-based corridor mapping field, as precision requirements can be achieved for single-pass operation with no need for traditional static ground control points.

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Molina, P., M. Blázquez, J. Sastre e I. Colomina. "PRECISION ANALYSIS OF POINT-AND-SCALE PHOTOGRAMMETRIC MEASUREMENTS FOR CORRIDOR MAPPING: PRELIMINARY RESULTS". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-3/W4 (17 marzo 2016): 85–90. http://dx.doi.org/10.5194/isprsarchives-xl-3-w4-85-2016.

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Abstract (sommario):

This paper addresses the key aspects of the sensor orientation and calibration approach within the mapKITE concept for corridor mapping, focusing on the contribution analysis of point-and-scale measurements of kinematic ground control points. MapKITE is a new mobile, simultaneous terrestrial and aerial, geodata acquisition and post-processing method. On one hand, the acquisition system is a tandem composed of a terrestrial mobile mapping system and an unmanned aerial system, the latter equipped with a remote sensing payload, and linked through a 'virtual tether', that is, a real-time waypoint supply from the terrestrial vehicle to the unmanned aircraft. On the other hand, mapKITE entails a method for geodata post-processing (specifically, sensor orientation and calibration) based on the described acquisition paradigm, focusing on few key aspects: the particular geometric relationship of a mapKITE network – the aerial vehicle always observes the terrestrial one as they both move –, precise air and ground trajectory determination – the terrestrial vehicle is regarded as a kinematic ground control point – and new photogrammetric measurements – pointing on and measuring the scale of an optical target on the roof of the terrestrial vehicle – are exploited. <br><br> In this paper, we analyze the performance of aerial image orientation and calibration in mapKITE for corridor mapping, which is the natural application niche of mapKITE, based on the principles and procedures of integrated sensor orientation with the addition of point-and-scale photogrammetric measurements of the kinematic ground control points. To do so, traditional (static ground control points, photogrammetric tie points, aerial control) and new (pointing-and-scaling of kinematic ground control points) measurements have been simulated for mapKITE corridor mapping missions, consisting on takeoff and calibration pattern, single-pass corridor operation potentially performing calibration patterns, and landing and calibration pattern. Our preliminary results show that the exterior orientation, interior orientation and tie points precision estimates are better when using kinematic control with few static ground control, and even with excluding the latter. We conclude then that mapKITE can be a breakthrough on the UAS-based corridor mapping field, as precision requirements can be achieved for single-pass operation with no need for traditional static ground control points.

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Olinichenko, Kateryna, Olga Priadko e Maksym Klymenko. "Marketing tools for promotion of educational services through social networks". Marketing and Digital Technologies 4, n. 3 (25 settembre 2020): 34–43. http://dx.doi.org/10.15276/mdt.4.3.2020.4.

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The aim of the article. The application of marketing mechanisms nowadays is an important component in the formation of an effective educational system in Ukraine. It is marketing, based on the formation of demand for educational services and its satisfaction, which provides integrated production and services sale management in the field of education. Insufficient attention is paid to promotion of educational services using Instagram social network, which is an effective tool for communication with the target audience. The aim of the article is to offer special tools for promotion of educational services through Instagram social network. The results of the analyses. Modern marketing communications make it possible to reveal both internal and external image of a higher educational institution to consumers, and social networks become an actual platform for interaction of all participants of educational process. Promotion of higher educational institution brand in social networks provides additional opportunities for segmentation and targeted information message. It is necessary to pay due attention to promotion of higher educational institution brand as it is connected with certain difficulties for applicants in choosing of an educational service. With the help of social networks, consumers of educational services can find necessary information about the higher educational institution by clicking on the link to the official website. Social networks are aimed at creation of loyal users, joining any of the communities; there is a possibility of constant contact of higher educational institution with target audience. One of the most effective directions to promote educational services at the present time is to use a social network. The article deals with marketing instruments for promotion of educational services through Instagram social network. The world statistical data regarding Instagram social network were analyzed. The main stages of algorithm for promotion of educational services in this social network were considered, including: landing page, setting up and launching of targeted advertising in Instagram social network with specific advertising objectives, contextual advertising in Google search engine; analysis and construction of sales funnel; development of mobile application; relations with target audience. In order to get to know the algorithm of an applicant’s actions regarding search for information on specialties and higher educational institution in social networks, we conducted a survey of first-year students of the Kharkiv State University of Food Technology and Trade on all specialties. The data were processed and a set of actions that are carried out by most applicants was formed. The essence of the instruments for promotion of educational services in Instagram was revealed. Proposals to create a digital presence of the website of higher educational institution were given. Conclusions and perspectives for further research. In general, in order to ensure stable functioning and development of educational services on the market, higher educational institution should operate in the categories and under the marketing principles, use tools and techniques, which are appropriate to marketing, taking into account the peculiarities of educational services, processes and results of their provision. Thus, successful promotion of educational services through Instagram social network takes place with formation of actual content and selection of effective marketing tools for promotion and advertising. Positive impression of higher educational institution in social networks will help it to form necessary reputation, will increase confidence by creating a positive public opinion. Key words: social networks, higher educational institution, promotion, advertising, educational services.

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Guo, Yangyang, Jiaqian Guo, Chang Liu, Hongting Xiong, Lilong Chai e Dongjian He. "Precision Landing Test and Simulation of the Agricultural UAV on Apron". Sensors 20, n. 12 (14 giugno 2020): 3369. http://dx.doi.org/10.3390/s20123369.

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Unmanned aerial vehicle (UAV) has been used to assist agricultural production. Precision landing control of UAV is critical for application of it in some specific areas such as greenhouses or livestock/poultry houses. For controlling UAV landing on a fixed or mobile apron/platform accurately, this study proposed an automatic method and tested it under three scenarios: (1) UAV landing at high operating altitude based on the GPS signal of the mobile apron; (2) UAV landing at low operating altitude based on the image recognition on the mobile apron; and (3) UAV landing progress control based on the fixed landing device and image detection to achieve a stable landing action. To verify the effectiveness of the proposed control method, apron at both stationary and mobile (e.g., 3 km/h moving speed) statuses were tested. Besides, a simulation was conducted for the UAV landing on a fixed apron by using a commercial poultry house as a model (135 L × 15 W × 3 H m). Results show that the average landing errors in high altitude and low altitude can be controlled within 6.78 cm and 13.29 cm, respectively. For the poultry house simulation, the landing errors were 6.22 ± 2.59 cm, 6.79 ± 3.26 cm, and 7.14 ± 2.41cm at the running speed of 2 km/h, 3 km/h, and 4 km/h, respectively. This study provides the basis for applying the UAV in agricultural facilities such as poultry or animal houses where requires a stricter landing control than open fields.

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Gautam, Alvika, Mandeep Singh, Pedda Baliyarasimhuni Sujit e Srikanth Saripalli. "Autonomous Quadcopter Landing on a Moving Target". Sensors 22, n. 3 (1 febbraio 2022): 1116. http://dx.doi.org/10.3390/s22031116.

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Autonomous landing on a moving target is challenging because of external disturbances and localization errors. In this paper, we present a vision-based guidance technique with a log polynomial closing velocity controller to achieve faster and more accurate landing as compared to that of the traditional vertical landing approaches. The vision system uses a combination of color segmentation and AprilTags to detect the landing pad. No prior information about the landing target is needed. The guidance is based on pure pursuit guidance law. The convergence of the closing velocity controller is shown, and we test the efficacy of the proposed approach through simulations and field experiments. The landing target during the field experiments was manually dragged with a maximum speed of 0.6 m/s. In the simulations, the maximum target speed of the ground vehicle was 3 m/s. We conducted a total of 27 field experiment runs for landing on a moving target and achieved a successful landing in 22 cases. The maximum error magnitude for successful landing was recorded to be 35 cm from the landing target center. For the failure cases, the maximum distance of vehicle landing position from target boundary was 60 cm.

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Feng, Yi, Cong Zhang, Stanley Baek, Samir Rawashdeh e Alireza Mohammadi. "Autonomous Landing of a UAV on a Moving Platform Using Model Predictive Control". Drones 2, n. 4 (12 ottobre 2018): 34. http://dx.doi.org/10.3390/drones2040034.

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Developing methods for autonomous landing of an unmanned aerial vehicle (UAV) on a mobile platform has been an active area of research over the past decade, as it offers an attractive solution for cases where rapid deployment and recovery of a fleet of UAVs, continuous flight tasks, extended operational ranges, and mobile recharging stations are desired. In this work, we present a new autonomous landing method that can be implemented on micro UAVs that require high-bandwidth feedback control loops for safe landing under various uncertainties and wind disturbances. We present our system architecture, including dynamic modeling of the UAV with a gimbaled camera, implementation of a Kalman filter for optimal localization of the mobile platform, and development of model predictive control (MPC), for guidance of UAVs. We demonstrate autonomous landing with an error of less than 37 cm from the center of a mobile platform traveling at a speed of up to 12 m/s under the condition of noisy measurements and wind disturbances.

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Bae, Hyansu, Jeongwook Lee e Kichang Lee. "Marker-Based 3D Position-Prediction Algorithm of Mobile Vertiport for Cabin-Delivery Mechanism of Dual-Mode Flying Car". Electronics 11, n. 12 (9 giugno 2022): 1837. http://dx.doi.org/10.3390/electronics11121837.

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This paper presents an image-processing technique for cabin delivery employing local localization and docking in a mobile station, which is a mobile vertiport for the use of dual-mode flying cars. A dual-mode flying automobile with an aerial electric vehicle (AEV), a ground electric vehicle (GEV), and a cabin is a future method of transportation that can be used in both the air and on the ground. To enable AEVs to land in a specific position, a landing site is necessary. The proposed AEV uses vertical take-off and landing, and a vertiport landing site is required. As vertical take-off and landing sites require a lot of space and are challenging to operate in multiple positions, we suggest a mobile vertiport that can fit into a small space. A mobile station is appropriate for dual-mode flying cars since it includes critical activities such as transporting AEVs from the ground and charging as well as a cabin-delivery system. The mobile station can generate a path to the AEV by calculating the relative position using the markers attached to the AEV and estimating the position of the landing AEV. The mobile station detects a marker for precise positioning correction, followed by exact position correction for cabin delivery, to travel to the accurate position of the AEV. To increase the success rate of cabin delivery, docking markers are identified and the angle position error between the mobile station and cabin is computed and corrected to rectify the position between the cabin and the mobile station for cabin delivery. In addition, the experimental results revealed a mechanically correctable error range that encompassed all experimental values. Consequently, this study showed that image processing may be used to create a mobile station for dual-mode flying automobiles.

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APOSTOLESCU, Nicolae, Ion TOMESCU, Dragos Daniel Ion GUTA e Radu BOGATEANU. "The autonomous control of landing on mobile platforms". INCAS BULLETIN 13, n. 3 (4 settembre 2021): 3–12. http://dx.doi.org/10.13111/2066-8201.2021.13.3.1.

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Abstract (sommario):

In this paper, we propose a simulation application that allows an aerial vehicle to land autonomously on a moving platform in the presence of uncertainties and disturbances. We have tested our method with various speeds and positions for the landing platform. In the context of this article, the autonomous control of landing on mobile platforms consists in synchronizing the movement of an aerial vehicle with the movement of the mobile platform. As a first step, the Spacelab INCAS laboratory group has developed an offline simulation application that allows an ABB robot to receive information on the movement of a Stewart-type mobile platform in order to conduct a landing process. The application can initiate a landing process on the mobile platform and guide the vehicle for perfect docking on the platform. Offline simulation allows the study of several scenarios of a robot working cell - the mobile platform before setting up the production cell. The offline application has a distributed client-server structure. The client communicates with the server through specific communication protocols. The client and server can reside on the same computer. The client application is developed in the Matlab environment and has as object the simulation and programming of the PS-6TL-1500 platform; the server one simulates and programs an ABB 7600-500/2.55 robot that moves on the track, in the RAPID language under RobotStudio ABB simulator.

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21

Sathitwattanasan, Ekarat, e Chinnapat Thipyopas. "Development of Deep Stall Landing System for Fixed-Wing Aircraft using Image Processing". E3S Web of Conferences 477 (2024): 00013. http://dx.doi.org/10.1051/e3sconf/202447700013.

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Abstract (sommario):

Currently, Unmanned Aerial Vehicle (UAV) plays a huge role, especially fixed-wing UAVs that can be used for various missions such as wide area survey work. It can also carry heavy loads over a long distance. And use less power. However, this type of UAV requires a relatively large runway or landing area. If the landing is used as a net landing, it will need a lot of space to install a net anyway. On the other hand, if using a multirotor UAV or Hybrid model (tilt-wing) that uses less space for take-off and landing. Nevertheless, there will be a limit on speed. If the wind is strong, it will not be able to fly and unable to carry enough load. Therefore, the organizers have foreseen the problem and fix the take-off and landing of fixed-wing UAV by using hand launch method for take-off while landing will use deep stall landing (GPS + Camera) that uses GPS to determine the radius zone 25 meters from the target to land in the start deep stall, in which this landing method will nose up until the angle of attack (AOA) is enough rates to cause the fixed-wing to lose lifting force and land at the specified point using camera to detect landing targets and adjusting the control surface on the fixed-wing elevator to land as close as possible to the specified point. It must be able to land closer to the target than using GPS or the pilot only. The results revealed that GPS landings had an average radius between the landing point and the target being 15.59 m. Pilot landings had an average radius between the landing point and the target being 14.71 m and GPS + Camera landing had an average the radius between the landing point and the target being 7.22 m. If the landing distance is calculated only the longitudinal axis, so GPS landing distance was 13.1 m. Pilot landing was 8.7 m and the GPS + Camera landing was 5.37 m. Furthermore, deep stall landing (GPS + Camera) can land closer than using GPS and pilot only.

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22

Wu, Lizhen, Chang Wang, Pengpeng Zhang e Changyun Wei. "Deep Reinforcement Learning with Corrective Feedback for Autonomous UAV Landing on a Mobile Platform". Drones 6, n. 9 (4 settembre 2022): 238. http://dx.doi.org/10.3390/drones6090238.

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Abstract (sommario):

Autonomous Unmanned Aerial Vehicle (UAV) landing remains a challenge in uncertain environments, e.g., landing on a mobile ground platform such as an Unmanned Ground Vehicle (UGV) without knowing its motion dynamics. A traditional PID (Proportional, Integral, Derivative) controller is a choice for the UAV landing task, but it suffers the problem of manual parameter tuning, which becomes intractable if the initial landing condition changes or the mobile platform keeps moving. In this paper, we design a novel learning-based controller that integrates a standard PID module with a deep reinforcement learning module, which can automatically optimize the PID parameters for velocity control. In addition, corrective feedback based on heuristics of parameter tuning can speed up the learning process compared with traditional DRL algorithms that are typically time-consuming. In addition, the learned policy makes the UAV landing smooth and fast by allowing the UAV to adjust its speed adaptively according to the dynamics of the environment. We demonstrate the effectiveness of the proposed algorithm in a variety of quadrotor UAV landing tasks with both static and dynamic environmental settings.

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23

Liang, Jianjian, Shoukun Wang e Bo Wang. "Online Motion Planning for Fixed-Wing Aircraft in Precise Automatic Landing on Mobile Platforms". Drones 7, n. 5 (18 maggio 2023): 324. http://dx.doi.org/10.3390/drones7050324.

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Abstract (sommario):

This paper proposes the creative idea that an unmanned fixed-wing aircraft should automatically adjust its 3D landing trajectory online to land on a given touchdown point, instead of following a pre-designed fixed glide slope angle or a landing path composed of two waypoints. A fixed-wing aircraft is a typical under-actuated and nonholonomic constrained system, and its landing procedure—which involves complex kinematic and dynamic constraints—is challenging, especially in some scenarios such as landing on an aircraft carrier, which has a runway that is very short and narrow. The conventional solution of setting a very conservative landing path in advance and controlling the aircraft to follow it without dynamic adjustment of the reference path has not performed satisfactorily due to the variation in initial states and widespread environmental uncertainties. The motion planner shown in this study can adjust an aircraft’s landing trajectory online and guide the aircraft to land at a given fixed or moving point while conforming to the strict constraints. Such a planner is composed of two parts: one is used to generate a series of motion primitives which conform to the dynamic constraints, and the other is used to evaluate those primitives and choose the best one for the aircraft to execute. In this paper, numerical simulations demonstrate that when given a landing configuration composed of position, altitude, and direction, the planner can provide a feasible guidance path for the aircraft to land accurately.

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24

Mirwan, Hamida B., e Peter G. Kevan. "Motion discrimination by Bombus impatiens (Hymenoptera: Apidae)". Canadian Entomologist 147, n. 5 (23 gennaio 2015): 580–91. http://dx.doi.org/10.4039/tce.2014.71.

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Abstract (sommario):

AbstractMobility of flowers in the wind has been proposed to affect the performances of pollinators in landing on flowers, nectar extraction, and pollen dispersal. Our study examined the preferences of worker Bombus impatiens Cresson (Hymenoptera: Apidae) for landing on and feeding from immobile or mobile artificial flower. Mobile flowers moved at varied frequencies (0.1–3.0 Hz) and in different directions, horizontal H (left to right wave) and vertical V (from en-face presentation at the lowest point to horizontal presentation at the zenith). We found that the bees showed no preference for mobile or immobile flowers. In general, we found that landing ability (time spent from the bees entering the testing arena to landing and starting to feed on the artificial flower) decreased as frequency (Hz) or speed of motion (cm/second) increased. Directionality of waving affected performance with the bees being able to forage from horizontally moving flowers better than from vertically moving flowers. Experience played a major role in improving individual performances. We also found that the bees could differentiate between horizontally and vertically waving flowers as well as between frequencies or speeds of motion.

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25

Li, Xiao Yong, Wei Kang Zhu, Jin Biao Zhou, Gui Ming Chen, Lei Yang e Hui Hua Wu. "Landing Point Predicting Method in Target Re-Entry Measurement". Applied Mechanics and Materials 596 (luglio 2014): 463–67. http://dx.doi.org/10.4028/www.scientific.net/amm.596.463.

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Abstract (sommario):

By introducing some atmospheric models and selecting methods for minimum integration step size and optimum initial integration value, a program of real time and near real time landing point predicting together with weighted processing methods of many groups of landing point parameters were put forward. Engineering application showed: the above methods and program improved real time and near real time landing point predicting precision more greatly compared with previously used methods, which had proved their broad applicability.

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26

Tichit, Pierre, Isabel Alves-dos-Santos, Marie Dacke e Emily Baird. "Accelerated landings in stingless bees are triggered by visual threshold cues". Biology Letters 16, n. 8 (agosto 2020): 20200437. http://dx.doi.org/10.1098/rsbl.2020.0437.

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Abstract (sommario):

Most flying animals rely primarily on visual cues to coordinate and control their trajectory when landing. Studies of visually guided landing typically involve animals that decrease their speed before touchdown. Here, we investigate the control strategy of the stingless bee Scaptotrigona depilis , which instead accelerates when landing on its narrow hive entrance. By presenting artificial targets that resemble the entrance at different locations on the hive, we show that these accelerated landings are triggered by visual cues. We also found that S. depilis initiated landing and extended their legs when the angular size of the target reached a given threshold. Regardless of target size, the magnitude of acceleration was the same and the bees aimed for the same relative position on the target suggesting that S. depilis use a computationally simple but elegant ‘stereotyped' landing strategy that requires few visual cues.

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27

Green, C. H. "The effects of odours and target colour on landing responses of Glossina morsitans morsitans and G. pallidipes (Diptera: Glossinidae)". Bulletin of Entomological Research 83, n. 4 (dicembre 1993): 553–62. http://dx.doi.org/10.1017/s0007485300039985.

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Abstract (sommario):

AbstractA laboratory bioassay was developed to allow blind testing of panels of odours for their effect on target-orientated behaviour of tsetse (Glossina spp.) in the laboratory. Landing responses of G. m. morsitans Westwood on black and blue targets were increased up to four-fold in the presence of carbon dioxide, but no significant effect of any other odours could be demonstrated. 2-methoxy phenol gave an apparent increase in landing behaviour in the laboratory, but this substance diminished rather than increased landing of G. pallidipes Austen and G. m. morsitans on targets in the field, as well as repelling tsetse from the target vicinity. Black, blue and red targets elicited strong landing behaviour in male G. m. morsitans in the laboratory, and white and yellow targets elicited little or none, whether carbon dioxide was present or not. In the field, high ultraviolet reflectivity increased landing behaviour of G. pallidipes, but only when there was a proportion of transmitted light through the target. Ultraviolet reflectivity always reduced overall attraction of tsetse to a single-coloured target. Two-coloured targets incorporating ultraviolet-reflecting white cloth obtained strong landing on the white panels, but caught fewer flies overall than all-black, or blue-and-black targets.

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28

Wan, Xiaoyan, Yongkang Shi e Peng Li. "Autonomous landing algorithm of UAV based on Target tracking". Journal of Physics: Conference Series 2450, n. 1 (1 marzo 2023): 012082. http://dx.doi.org/10.1088/1742-6596/2450/1/012082.

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Abstract (sommario):

Abstract The target tracking technology in the UAV autonomous landing process is studied. Based on the analysis of the occlusion, background change, and variable scale problems in the target tracking process, a scale adaptive method for UAV target tracking based on KCF (Kernelized Correlation Filter) algorithm is proposed. The original KCF target tracking framework is adopted to achieve the target position prediction function. Secondly, to address the variable scale problem of moving targets and the target loss problem caused by scale changes, the scale filter of the DSST target tracking algorithm is used. The algorithm is for estimating the scale of moving targets and generating a small-scale filter estimate to improve the tracking efficiency of the UAV for moving targets and reduce the target loss rate. The final test on the OTB dataset showed a 4% improvement in variable scale accuracy and a 2.9% improvement in variable scale success rate. A Gazebo 3D environment scene was set up under the Linux system, and UAV autonomous landing simulation experiments were conducted to verify the improved algorithm’s real-time effectiveness in the UAV autonomous landing application. The simulation results show that the improved KCF target tracking algorithm has real-time performance in the UAV autonomous landing trajectory tracking process.

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29

Wu, Dong, Hang Zhu e Yubin Lan. "A Method for Designated Target Anti-Interference Tracking Combining YOLOv5 and SiamRPN for UAV Tracking and Landing Control". Remote Sensing 14, n. 12 (12 giugno 2022): 2825. http://dx.doi.org/10.3390/rs14122825.

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Abstract (sommario):

With the rapid development in the field of computer vision, the vision-based approach to unmanned aerial vehicle (UAV) tracking and landing technology in weak global positioning system (GPS) or GPS-free environments has become prominent in military and civilian missions. However, this technique still suffers from problems such as interference by similar targets in the environment, low tracking accuracy, slow processing speed, and poor stability. To solve these problems, we propose the designated target anti-interference tracking (DTAT) method, which integrates YOLOv5 and SiamRPN, and built a system to achieve UAV tracking and the landing of a designated target in an environment with multiple interference targets. The system consists of the following parts: first, an image is acquired by a monocular camera to obtain the pixel position information of the designated target. Next, the position of the UAV relative to the target is estimated based on the pixel location information of the target and the known target size information. Finally, the discrete proportion integration differentiation (PID) control law is used to complete the target tracking and landing task of the UAV. To test the system performance, we deployed it on a robot operating system (ROS) platform, conducted many simulation experiments, and observed the real-time trajectories of the UAV and the target through Gazebo software. The results show that the relative distance between the UAV and the target during the tracking process when the target was moving at 0.6 m/s does not exceed 0.8 m, and the landing error of the UAV during the landing process after the target is stationary does not exceed 0.01 m. The results validate the effectiveness and robustness of the system and lay a foundation for subsequent research.

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30

Moudpoklang, Jeerasak, e Viboon Sangveraphunsiri. "An Altitude Estimation Technique for Autonomous Landing of a Quad-Rotor Using a Vision System". Applied Mechanics and Materials 619 (agosto 2014): 209–13. http://dx.doi.org/10.4028/www.scientific.net/amm.619.209.

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Abstract (sommario):

This research work is to purpose a technique for autonomous landing of a quad-rotor by using the estimating of its altitude. The landing of the quad-rotor is in vertical direction. The detail about the design of a Landing Pad Target used for autonomous landing is explained. The autonomous landing procedure will include a mapping of the information on the detected landing pad to an altitude by using an altitude estimation algorithm with the Kalman filter. The information on the landing pad is in a form of graphic information which is easily to map to the estimated altitude of the quad-rotor used in the autonomous landing. The approximate errors from the estimation of the altitudes are within 1 cm. for 2 m. height. The control strategy is that the autonomous landing will start at an altitude of 10 meters while the landing target can be detected within this range. From the height between 10 m. to 3 m., the attached barometer is used for measurement of height and the vision system is used to estimate the height when the quad-rotor is lower than 3 m. From the experimental results, the effectiveness of the design of the landing pad, used with an appropriate control strategy, the approximate accuracy of 2 cm can be achieved. Most of the errors occur because during the last approach of landing, the height cannot be estimated from the vision but it is estimated from the measurement of the acceleration of the quad-rotor instead. Our purposed landing procedure is very promising for the autonomous landing of a quad-rotor and it can be implemented in real application.

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31

Xu, Rui, e Sheng Ying Zhu. "Relative Position and Attitude Determination for Robotic Mars Soft Landing Using Multi-Point Laser Rangefinder". Advanced Materials Research 381 (novembre 2011): 118–22. http://dx.doi.org/10.4028/www.scientific.net/amr.381.118.

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Abstract (sommario):

Several international deep space exploration plans aimed at Mars landing and surface sample returning. Because of the communication delay between Earth and Mars and the lack of information on the Mars complicated surface, autonomous landing at selected location is required. Based on multi-point laser rangefinder and optical navigation camera, the relative position and attitude rapid determination algorithm is present in order to ensure precise and safe landing. To get the normal direction of the landing plane and the target point position, the geometry relation of laser measure vectors and target point are used. Finally, performance of the autonomous relative position and attitude determination system is verified using the numerical simulation. The results show that the proposed methods can achieve accurate position and attitude determination.

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32

Zhou, Jiexin, Qiufu Wang, Zhuo Zhang e Xiaoliang Sun. "Aircraft Carrier Pose Tracking Based on Adaptive Region in Visual Landing". Drones 6, n. 7 (21 luglio 2022): 182. http://dx.doi.org/10.3390/drones6070182.

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Abstract (sommario):

Due to its structural simplicity and its strong anti-electromagnetic ability, landing guidance based on airborne monocular vision has gained more and more attention. Monocular 6D pose tracking of the aircraft carrier is one of the key technologies in visual landing guidance. However, owing to the large range span in the process of carrier landing, the scale of the carrier target in the image variates greatly. There is still a lack of robust monocular pose tracking methods suitable for this scenario. To tackle this problem, a new aircraft carrier pose tracking algorithm based on scale-adaptive local region is proposed in this paper. Firstly, the projected contour of the carrier target is uniformly sampled to establish local circular regions. Then, the local area radius is adjusted according to the pixel scale of the projected contour to build the optimal segmentation energy function. Finally, the 6D pose tracking of the carrier target is realized by iterative optimization. Experimental results on both synthetic and real image sequences show that the proposed method achieves robust and efficient 6D pose tracking of the carrier target under the condition of large distance span, which meets the application requirements of carrier landing guidance.

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33

Li, Fuyang, Zhiguo Wu, Jingyu Li, Zhitong Lai, Botong Zhao e Chen Min. "A Multi-Step CNN-Based Estimation of Aircraft Landing Gear Angles". Sensors 21, n. 24 (17 dicembre 2021): 8440. http://dx.doi.org/10.3390/s21248440.

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Abstract (sommario):

This paper presents a method for measuring aircraft landing gear angles based on a monocular camera and the CAD aircraft model. Condition monitoring of the aircraft landing gear is a prerequisite for the safe landing of the aircraft. Traditional manual observation has an intense subjectivity. In recent years, target detection models dependent on deep learning and pose estimation methods relying on a single RGB image have made significant progress. Based on these advanced algorithms, this paper proposes a method for measuring the actual angles of landing gears in two-dimensional images. A single RGB image of an aircraft is inputted to the target detection module to obtain the key points of landing gears. The vector field network votes the key points of the fuselage after extraction and scale normalization of the pixels inside the aircraft prediction box. Knowing the pixel position of the key points and the constraints on the aircraft, the angle between the landing gear and fuselage plane can be calculated even without depth information. The vector field loss function is improved based on the distance between pixels and key points, and synthetic datasets of aircraft with different angle landing gears are created to verify the validity of the proposed algorithm. The experimental results show that the mean error of the proposed algorithm for the landing gears is less than 5 degrees on the light-varying dataset.

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34

Kownacki, Cezary, Leszek Ambroziak, Maciej Ciężkowski, Adam Wolniakowski, Sławomir Romaniuk, Arkadiusz Bożko e Daniel Ołdziej. "Precision Landing Tests of Tethered Multicopter and VTOL UAV on Moving Landing Pad on a Lake". Sensors 23, n. 4 (10 febbraio 2023): 2016. http://dx.doi.org/10.3390/s23042016.

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Abstract (sommario):

Autonomous take-off and landing on a moving landing pad are extraordinarily complex and challenging functionalities of modern UAVs, especially if they must be performed in windy environments. The article presents research focused on achieving such functionalities for two kinds of UAVs, i.e., a tethered multicopter and VTOL. Both vehicles are supported by a landing pad navigation station, which communicates with their ROS-based onboard computer. The computer integrates navigational data from the UAV and the landing pad navigational station through the utilization of an extended Kalman filter, which is a typical approach in such applications. The novelty of the presented system is extending navigational data with data from the ultra wide band (UWB) system, and this makes it possible to achieve a landing accuracy of about 1 m. In the research, landing tests were carried out in real conditions on a lake for both UAVs. In the tests, a special mobile landing pad was built and based on a barge. The results show that the expected accuracy of 1 m is indeed achieved, and both UAVs are ready to be tested in real conditions on a ferry.

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35

Tichit, Pierre, Isabel Alves-dos-Santos, Marie Dacke e Emily Baird. "Accelerated landing in a stingless bee and its unexpected benefits for traffic congestion". Proceedings of the Royal Society B: Biological Sciences 287, n. 1921 (19 febbraio 2020): 20192720. http://dx.doi.org/10.1098/rspb.2019.2720.

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Abstract (sommario):

To land, flying animals must simultaneously reduce speed and control their path to the target. While the control of approach speed has been studied in many different animals, little is known about the effect of target size on landing, particularly for small targets that require precise trajectory control. To begin to explore this, we recorded the stingless bees Scaptotrigona depilis landing on their natural hive entrance—a narrow wax tube built by the bees themselves. Rather than decelerating before touchdown as most animals do, S. depilis accelerates in preparation for its high precision landings on the narrow tube of wax. A simulation of traffic at the hive suggests that this counterintuitive landing strategy could confer a collective advantage to the colony by minimizing the risk of mid-air collisions and thus of traffic congestion. If the simulated size of the hive entrance increases and if traffic intensity decreases relative to the measured real-world values, ‘accelerated landing' ceases to provide a clear benefit, suggesting that it is only a useful strategy when target cross-section is small and landing traffic is high. We discuss this strategy in the context of S. depilis ' ecology and propose that it is an adaptive behaviour that benefits foraging and nest defence.

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36

Guo, Jinglong, Xin Dong, Yang Gao, Daochun Li e Zhan Tu. "Simultaneous Obstacles Avoidance and Robust Autonomous Landing of a UAV on a Moving Vehicle". Electronics 11, n. 19 (28 settembre 2022): 3110. http://dx.doi.org/10.3390/electronics11193110.

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Abstract (sommario):

For unmanned aerial vehicles (UAVs), landing on a moving vehicle robustly is an open challenge, especially under cluttered surroundings with the presence of unknown obstacles. Those undesired environmental factors could induce collisions and thus affect flight safety significantly. Currently, there are few solutions to address such a challenge. In this paper, we propose a systematic autonomous landing scheme that enables the robust autonomous landing performance of a quadrotor UAV. The proposed scheme integrates target detection, state estimation, trajectory planning, and landing control. The position and attitude information of the target ground vehicle and the test quadrotor are estimated by the onboard vision system and GPS. In order to detect landing markers at different altitudes, a particular landing pad with an Apriltag bundle is implemented. As a typical aerial–terrestrial cooperation system, the trajectory planner of the quadrotor updates continuously to avoid obstacles via real-time sensing and re-planning. A finite state machine is used to label the current flight status and triggers the control laws correspondingly. The effectiveness of the proposed method has been validated in a high-fidelity simulator with environmental obstacles.

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37

Sortland, Venke Marie, e Ina Coll Kjølmoen. "Landing - dansekunstnere med stedssans". Nordic Journal of Dance 2, n. 1 (1 dicembre 2011): 2–7. http://dx.doi.org/10.2478/njd-2011-0002.

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Abstract (sommario):

Abstract The performance group Landing was established in 2005 by 11 dance and performing artists, with an artistic vision to create site-specific dance projects. In 2008 Landing created an extensive site-specific project at the fully running St Olavs Hospital in Trondheim that was entitled Landing08. In this article we will share some of our experiences of this project. In 2010 Landing was reorganized into a production unit lead by us. Our aim is to initiate, produce, and support art projects that challenge target groups, sites and formats of presentation.

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38

Ge, Zijian, Jingjing Jiang, Ewan Pugh, Ben Marshall, Yunda Yan e Liang Sun. "Vision-Based UAV Landing with Guaranteed Reliability in Adverse Environment". Electronics 12, n. 4 (15 febbraio 2023): 967. http://dx.doi.org/10.3390/electronics12040967.

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Abstract (sommario):

Safe and accurate landing is crucial for Unmanned Aerial Vehicles (UAVs). However, it is a challenging task, especially when the altitude of the landing target is different from the ground and when the UAV is working in adverse environments, such as coasts where winds are usually strong and changing rapidly. UAVs controlled by traditional landing algorithms are unable to deal with sudden large disturbances, such as gusts, during the landing process. In this paper, a reliable vision-based landing strategy is proposed for UAV autonomous landing on a multi-level platform mounted on an Unmanned Ground Vehicle (UGV). With the proposed landing strategy, visual detection can be retrieved even with strong gusts and the UAV is able to achieve robust landing accuracy in a challenging platform with complex ground effects. The effectiveness of the landing algorithm is verified through real-world flight tests. Experimental results in farm fields demonstrate the proposed method’s accuracy and robustness to external disturbances (e.g., wind gusts).

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39

Deng, Yanpeng, Rongjun Mu e Peng Wu. "Optimal Landing Zone Selection and Online Trajectory Programming Method for Lunar Lander". Journal of Physics: Conference Series 2551, n. 1 (1 luglio 2023): 012029. http://dx.doi.org/10.1088/1742-6596/2551/1/012029.

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Abstract (sommario):

Abstract To achieve a safe landing on the lunar surface with complex terrain, online landing zone selection is required. A DEM-based landing zone selection technique is proposed. The method firstly obtains several candidate landing zones by analyzing the gradient and variance information from the DEM, and then selects the integrated candidate landing zone by the overlap ratio. Finally, the optimal trajectory programming is carried out with the current state of the lander as the initial value and each integrated candidate landing zone as the final position, and the optimal landing zone is selected by comparing the required fuel to each landing zone. Compared with the classical DEM-based online landing site selection technique, the proposed method does not perform terrain reconstruction, responds quickly, and achieves real-time performance, and it also reduces fuel consumption, provides residual fuel for the subsequent landing phase, and increases the reliability of the landing process. Simulation results show that the proposed method is able to select several candidate landing zones in complex terrain, meanwhile, it is capable of achieving the optimal trajectory programming with the target of these several candidate landing zones, and finally, the optimal landing zone is selected by comparing the fuel consumption of each path.

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40

Chen, Danhe, Chuangyi Li e Zhou Su. "Dynamics Research and Analysis of landing on the surface of Asteroid". Journal of Physics: Conference Series 2472, n. 1 (1 maggio 2023): 012033. http://dx.doi.org/10.1088/1742-6596/2472/1/012033.

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Abstract (sommario):

Abstract Asteroid detection has been the main research field of deep space exploration, and even in the future years. Countries have carried out missions to flyby and landing on the surface of asteroids, the sampling can help human explore the origins of small bodies, as well as origin of the solar system. While the particular environmental factors such as small size and low gravity of asteroids make the landing more difficult, this paper designs a four-legged inverted triangle soft lander, supplemented by thrust reversers and rope anchors for stable landing. A mathematical model of the lander landing on the surface of target asteroid is established, and the motion and dynamic response of lander in different landing modes is studied, conditions and safe landing range is well defined. Results of the analysis have demonstrated the effectiveness of dynamic landing model for the proposed lander.

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41

Aagten-Murphy, David, e Paul M. Bays. "Automatic and intentional influences on saccade landing". Journal of Neurophysiology 118, n. 2 (1 agosto 2017): 1105–22. http://dx.doi.org/10.1152/jn.00141.2017.

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Abstract (sommario):

When making an eye movement to a target location, the presence of a nearby distractor can cause the saccade to unintentionally terminate at the distractor itself or the average position in between stimuli. With probabilistic mixture models, we quantified how both unavoidable capture and goal-directed targeting were influenced by changing the task and the target-distractor separation. Using this novel technique, we could extract the time course over which automatic and intentional processes compete for control of saccades.

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42

Hou, Weijie, Yongbo Hao, Chang Wang, Lei Chen, Guangping Li, Baoshan Zhao, Hao Wang et al. "Theoretical and Experimental Investigations on High-Precision Micro-Low-Gravity Simulation Technology for Lunar Mobile Vehicle". Sensors 23, n. 7 (25 marzo 2023): 3458. http://dx.doi.org/10.3390/s23073458.

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Abstract (sommario):

With the development of space technology, the functions of lunar vehicles are constantly enriched, and the structure is constantly complicated, which puts forward more stringent requirements for its ground micro-low-gravity simulation test technology. This paper puts forward a high-precision and high-dynamic landing buffer test method based on the principle of magnetic quasi-zero stiffness. Firstly, the micro-low-gravity simulation system for the lunar vehicle was designed. The dynamic model of the system and a position control method based on fuzzy PID parameter tuning were established. Then, the dynamic characteristics of the system were analyzed through joint simulation. At last, a prototype of the lunar vehicle’s vertical constant force support system was built, and a micro-low-gravity landing buffer test was carried out. The results show that the simulation results were in good agreement with the test results. The sensitivity of the system was better than 0.1%, and the constant force deviation was 0.1% under landing impact conditions. The new method and idea are put forward to improve the micro-low-gravity simulation technology of lunar vehicles.

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43

Mu, Rongjun, Yanpeng Deng e Peng Wu. "Adaptive Convex Optimization Guidance for Lunar Landing". Aerospace 10, n. 7 (13 luglio 2023): 634. http://dx.doi.org/10.3390/aerospace10070634.

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In this paper, a novel guidance algorithm based on adaptive convex optimization is proposed to ensure robustness in the uncertainty of a lunar lander’s parameters and satisfy the constraints of terminal position, velocity, attitude, and thrust. To address the problem of parameter uncertainty in the landing process, the parameter-adaptive method is used to achieve online real-time optimal estimations of specific impulse and mass by the optimal observer, and the estimated parameters are used to realize optimal trajectory programming. To overcome the difficulty in constraining the attitude and the thrust level at the final stage in the convex optimization process, a rapid adjustment phase is added to meet the final attitude and thrust constraints; the target-adaptive method is used to adjust the target adaptively at the same time. Therefore, the position and velocity deviations caused by the rapid adjustment phase can be eliminated by the target offset. Finally, the results of numerical experiments demonstrate the effectiveness of the proposed algorithm.

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Bautista, Nicolas, Hector Gutierrez, John Inness e John Rakoczy. "Precision Landing of a Quadcopter Drone by Smartphone Video Guidance Sensor in a GPS-Denied Environment". Sensors 23, n. 4 (9 febbraio 2023): 1934. http://dx.doi.org/10.3390/s23041934.

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This paper describes the deployment, integration, and demonstration of a Smartphone Video Guidance Sensor (SVGS) as a novel technology for autonomous 6-DOF proximity maneuvers and precision landing of a quadcopter drone. The proposed approach uses a vision-based photogrammetric position and attitude sensor (SVGS) to estimate the position of a landing target after video capture. A visual inertial odometry sensor (VIO) is used to provide position estimates of the UAV in a ground coordinate system during flight on a GPS-denied environment. The integration of both SVGS and VIO sensors enables the accurate updating of position setpoints during landing, providing improved performance compared with VIO-only landing, as shown in landing experiments. The proposed technique also shows significant operational advantages compared with state-of-the-art sensors for indoor landing, such as those based on augmented reality (AR) markers.

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Dong, Xin, Yuzhe Gao, Jinglong Guo, Shiyu Zuo, Jinwu Xiang, Daochun Li e Zhan Tu. "An Integrated UWB-IMU-Vision Framework for Autonomous Approaching and Landing of UAVs". Aerospace 9, n. 12 (5 dicembre 2022): 797. http://dx.doi.org/10.3390/aerospace9120797.

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Unmanned Aerial Vehicles (UAVs) autonomous approaching and landing on mobile platforms always play an important role in various application scenarios. Such a complicated autonomous task requires an integrated multi-sensor system to guarantee environmental adaptability in contrast to using each sensor individually. Multi-sensor fusion perception demonstrates great feasibility to compensate for adverse visual events, undesired vibrations of inertia sensors, and satellite positioning loss. In this paper, a UAV autonomous landing scheme based on multi-sensor fusion is proposed. In particular, Ultra Wide-Band (UWB) sensor, Inertial Measurement Unit (IMU), and vision feedback are integrated to guide the UAV to approach and land on a moving object. In the approaching stage, a UWB-IMU-based sensor fusion algorithm is proposed to provide relative position estimation of vehicles with real time and high consistency. Such a sensor integration addresses the open challenge of inaccurate satellite positioning when the UAV is near the ground. It can also be extended to satellite-denied environmental applications. When the landing platform is detected by the onboard camera, the UAV performs autonomous landing. In the landing stage, the vision sensor is involved. With the visual feedback, a deep-learning-based detector and local pose estimator are enabled when the UAV approaches the landing platform. To validate the feasibility of the proposed autonomous landing scheme, both simulation and real-world experiments in extensive scenes are performed. As a result, the proposed landing scheme can land successfully with adequate accuracy in most common scenarios.

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Sandvig, J. Christopher. "Mobilization Techniques Utilized by Leading Global E-Commerce Sites". International Journal of E-Business Research 12, n. 2 (aprile 2016): 1–16. http://dx.doi.org/10.4018/ijebr.2016040101.

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The objective of this study is to improve our understanding of website mobilization techniques. The landing pages of Alexa's 527 top global shopping sites were analyzed for mobilization technique, mobile usability, and data requirements. It also investigates how mobile technique impacts Google mobile search results. The study found that 89.3% of top global shopping sites are mobile-friendly. The most popular mobile technique is to redirect mobile users to a separate URL, commonly known as m.sites, utilized by 44.1% of sites, followed by dynamic serving, utilized by 23.8%, and responsive, utilized by 23.0% of sites. Keyword analysis using the SEMRush service found a statistically significant difference in keywords following Google's algorithm change to favor mobile sites.

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Hancock, Bill. "Hacker Target: Mobile Phones". Computers & Security 19, n. 6 (ottobre 2000): 494–95. http://dx.doi.org/10.1016/s0167-4048(00)06018-1.

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Lin, Yunhan, Wenlong Ji, Haowei He e Yaojie Chen. "Two-Stage Water Jet Landing Point Prediction Model for Intelligent Water Shooting Robot". Sensors 21, n. 8 (12 aprile 2021): 2704. http://dx.doi.org/10.3390/s21082704.

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In this paper, an intelligent water shooting robot system for situations of carrier shake and target movement is designed, which uses a 2 DOF (degree of freedom) robot as an actuator, a photoelectric camera to detect and track the desired target, and a gyroscope to keep the robot’s body stable when it is mounted on the motion carriers. Particularly, for the accurate shooting of the designed system, an online tuning model of the water jet landing point based on the back-propagation algorithm was proposed. The model has two stages. In the first stage, the polyfit function of Matlab is used to fit a model that satisfies the law of jet motion in ideal conditions without interference. In the second stage, the model uses the back-propagation algorithm to update the parameters online according to the visual feedback of the landing point position. The model established by this method can dynamically eliminate the interference of external factors and realize precise on-target shooting. The simulation results show that the model can dynamically adjust the parameters according to the state relationship between the landing point and the desired target, which keeps the predicted pitch angle error within 0.1°. In the test on the actual platform, when the landing point is 0.5 m away from the position of the desired target, the model only needs 0.3 s to adjust the water jet to hit the target. Compared to the state-of-the-art method, GA-BP (genetic algorithm-back-propagation), the proposed method’s predicted pitch angle error is within 0.1 degree with 1/4 model parameters, while costing 1/7 forward propagation time and 1/200 back-propagation calculation time.

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Subramanian, Jayasurya Arasur, Vijanth Sagayan Asirvadam, Saiful Azrin B. M. Zulkifli, Narinderjit Singh Sawaran Singh, N. Shanthi e Ravi Kumar Lagisetty. "Target Localization for Autonomous Landing Site Detection: A Review and Preliminary Result with Static Image Photogrammetry". Drones 7, n. 8 (2 agosto 2023): 509. http://dx.doi.org/10.3390/drones7080509.

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The advancement of autonomous technology in Unmanned Aerial Vehicles (UAVs) has piloted a new era in aviation. While UAVs were initially utilized only for the military, rescue, and disaster response, they are now being utilized for domestic and civilian purposes as well. In order to deal with its expanded applications and to increase autonomy, the ability for UAVs to perform autonomous landing will be a crucial component. Autonomous landing capability is greatly dependent on computer vision, which offers several advantages such as low cost, self-sufficiency, strong anti-interference capability, and accurate localization when combined with an Inertial Navigation System (INS). Another significant benefit of this technology is its compatibility with LiDAR technology, Digital Elevation Models (DEM), and the ability to seamlessly integrate these components. The landing area for UAVs can vary, ranging from static to dynamic or complex, depending on their environment. By comprehending these characteristics and the behavior of UAVs, this paper serves as a valuable reference for autonomous landing guided by computer vision and provides promising preliminary results with static image photogrammetry.

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Sawai, Shujiro, Jun 'ichiro Kawaguchi, Daniel Scheeres, Naoki Yoshizawa e Masahiro Ogasawara. "Development of a Target Marker for Landing on Asteroids". Journal of Spacecraft and Rockets 38, n. 4 (luglio 2001): 601–8. http://dx.doi.org/10.2514/2.3723.

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