global coordinate system
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2021 ◽  
pp. 224-230
Author(s):  
Konstantin Amelin ◽  
Vladimir Maltsev

In the modern world, UAVs (unmanned aerial vehicles) are increasingly used in everyday life in solving civilian tasks. One of the main applications of UAVs is data collection with their reference to a given coordinate system. For example, for the task of aerial photography, it is necessary to accurately link each image to the global coordinate system. In addition to the exact location of coordinates, it is worth the exact movement of a given route, to collect data of exactly those places that are needed. Thus, it is very important to ensure the minimum deviation of the UAV from the given route under the conditions of external disturbances (wind disturbances) acting on it. The article describes a procedure for assessing wind speed and direction for a UAV control system using the SPSA method. The simulation results of the algorithm operation, confirmed during flight tests on an ultralight UAV with an ardupilot autopilot, are presented.


Author(s):  
Наталія Решетняк ◽  
Олена Назаренко ◽  
Юлія Єгорова

The need to ensure balanced innovative development of Ukraine is due to global uncertainty, dynamic processes and structural changes that are taking place today in the global economy. In these conditions, it is relevant to determine the position of Ukraine in the global coordinate system precisely in terms of innovation. Assessment of the state of the scientific and technical sphere, innovative development, research results in the countries of the world at the international level is carried out according to many indicators of various ratings, the most authoritative of which are: Global Innovation Index, Global Competitiveness Index, European Innovation Scoreboard. An analysis of the achieved level of innovative development of the Ukrainian economy in terms of international ratings requires the determination of methodological principles for their calculation. According to the results of the study, it was found that, despite some positive trends, in general, there is a significant gap between the level of innovative development of Ukraine and developed countries. It was found that the position of our country on the Global Competitiveness Index in the past few years has fluctuated between 76-89 places, in accordance with which, it is concluded that there are no effective reforms in the field of research, technology and innovation. The study of innovative activities of European countries and countries - regional neighbors demonstrated Ukraine's membership in the group with the status of «Modest Innovator». Low values of the analyzed indicators in international ratings are associated with errors in government policy and existing problems in the innovation sphere - the use of human potential, the quality of innovation infrastructure, the formation of sustainable relationships between elements of the national innovation system as a whole. The issues of cooperation with international institutions and poor integration into international scientific, technical and innovative cooperation remain unresolved. In this regard, steps are proposed in the direction of Ukraine joining the global innovation processes, which will bring the rating results closer to the level of developed countries in the future.


Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7088
Author(s):  
Wenhao Huang ◽  
Kai Xue ◽  
Qiuhong Li

Functionally graded materials (FGMs) structures are increasingly used in engineering due to their superior mechanical and material properties, and the FGMs plate with cutouts is a common structural form, but research on the vibration characteristics of FGMs plate with cutouts is relatively limited. In this paper, the three-dimensional exact solution for the vibration analysis of FGMs rectangular plate with circular cutouts subjected to general boundary conditions is presented based on the three-dimensional elasticity theory. The displacement field functions are expressed as standard cosine Fourier series plus auxiliary cosine series terms satisfying the boundary conditions in the global coordinate system. The plate with circular cutout is discretized into four curve quadrilateral sub-domains using the p-version method, and then the blending function method is applied to map the closed quadrilateral region to the computational space. The characteristic equation is obtained based on the Lagrangian energy principle and Rayleigh–Ritz method. The efficiency and reliability of proposed method are verified by comparing the present results with those available in the literature and FEM methods. Finally, a parametric study is investigated including the cutout sizes, the cutout positions, and the cutout numbers from the free vibration characteristic analysis and the harmonic analysis. The results can serve as benchmark data for other research on the vibration of FGMs plates with cutouts.


2021 ◽  
Vol 11 (18) ◽  
pp. 8404
Author(s):  
Rafael Caballero ◽  
Jesús Parra ◽  
Miguel Ángel Trujillo ◽  
Francisco J. Pérez-Grau ◽  
Antidio Viguria ◽  
...  

The inspection of public infrastructure, such as viaducts and bridges, is crucial for their proper maintenance given the heavy use of many of them. Current inspection techniques are very costly and manual, requiring highly qualified personnel and involving many risks. This article presents a novel solution for the detailed inspection of viaducts using aerial robotic platforms. The system provides a highly automated visual inspection platform that does not rely on GPS and could even fly underneath the infrastructure. Unlike commercially available solutions, our system automatically references the inspection to a global coordinate system usable throughout the lifespan of the infrastructure. In addition, the system includes another aerial platform with a robotic arm to make contact inspections of detected defects, thus providing information that cannot be obtained only with images. Both aerial robotic platforms feature flexibility in the choice of camera or contact measurement sensors as the situation requires. The system was validated by performing inspection flights on real viaducts.


Author(s):  
Yang Liu ◽  
Chengdong Lin ◽  
Zhenjiang Li

This paper presents WR-Hand, a wearable-based system tracking 3D hand pose of 14 hand skeleton points over time using Electromyography (EMG) and gyroscope sensor data from commercial armband. This system provides a significant leap in wearable sensing and enables new application potentials in medical care, human-computer interaction, etc. A challenge is the armband EMG sensors inevitably collect mixed EMG signals from multiple forearm muscles because of the fixed sensor positions on the device, while prior bio-medical models for hand pose tracking are built on isolated EMG signal inputs from isolated forearm spots for different muscles. In this paper, we leverage the recent success of neural networks to enhance the existing bio-medical model using the armband's EMG data and visualize our design to understand why our solution is effective. Moreover, we propose solutions to place the constructed hand pose reliably in a global coordinate system, and address two practical issues by providing a general plug-and-play version for new users without training and compensating for the position difference in how users wear their armbands. We implement a prototype using different commercial armbands, which is lightweight to execute on user's phone in real-time. Extensive evaluation shows the efficacy of the WR-Hand design.


2021 ◽  
Author(s):  
Ce Mai ◽  
Yongsheng Rao ◽  
Hao Guan ◽  
Linjing Zhang ◽  
Jietong Zhao ◽  
...  

2021 ◽  
Vol 2021 (3) ◽  
pp. 4534-4539
Author(s):  
S. Brier ◽  
◽  
J. Regel ◽  
M. Putz ◽  
M. Dix ◽  
...  

The paper presents a numerical simulation of thermal induced tool displacement during milling oper-ation. An unidirectional finite element model is developed which consists of two sections. A CFX model and a thermal transient model. With the aid of CFX module, the conjugated heat transfer be-tween milling tool and coolant fluid is described. The result of these efforts is the body temperature field of the end mill cutter due to thermal load, which is the thermal fingerprint of the cutting process. Subsequently the calculated body temperature field is linked with a transient-structural module to cal-culate the resulting thermal elastic displacement of the milling cutter. The thermo-elastic displace-ment of the tool is determined by examining a pilot node at the tip of the end mill, whose displace-ment is calculated in relation to the global coordinate system of the model.


Author(s):  
M. Chen ◽  
Q. Zhang

Abstract. In order to probe into the characteristics of positioning deviation between Beidou Navigation Satellite System (Beidou) and global positioning system (GPS), and investigate possible contribution of Beidou data to refinement of global coordinate system, refined calculation is made on observation data of 240 national reference stations that are distributed uniformly across China on the whole in this study. These stations support satellite signals of four global navigation satellite systems, including Beidou, GPS, GLONASS and Galileo, and a 5-year time span from 2016 to 2020 is adopted. In this study, PPP is calculated based on GPS data and Beidou single system data in no-difference resolution network mode, and accurate coordinates of national reference stations in two processing modes are obtained. Analysis of difference between the calculations based on Beidou data and on GPS data shows that the consistency between Beidou and GPS positioning results reaches about 5 mm in the east and in the north, and about 1.3 cm in the height direction.


Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4374
Author(s):  
Jose Bernardo Martinez ◽  
Hector M. Becerra ◽  
David Gomez-Gutierrez

In this paper, we addressed the problem of controlling the position of a group of unicycle-type robots to follow in formation a time-varying reference avoiding obstacles when needed. We propose a kinematic control scheme that, unlike existing methods, is able to simultaneously solve the both tasks involved in the problem, effectively combining control laws devoted to achieve formation tracking and obstacle avoidance. The main contributions of the paper are twofold: first, the advantages of the proposed approach are not all integrated in existing schemes, ours is fully distributed since the formulation is based on consensus including the leader as part of the formation, scalable for a large number of robots, generic to define a desired formation, and it does not require a global coordinate system or a map of the environment. Second, to the authors’ knowledge, it is the first time that a distributed formation tracking control is combined with obstacle avoidance to solve both tasks simultaneously using a hierarchical scheme, thus guaranteeing continuous robots velocities in spite of activation/deactivation of the obstacle avoidance task, and stability is proven even in the transition of tasks. The effectiveness of the approach is shown through simulations and experiments with real robots.


Author(s):  
Niklas Holzwarth ◽  
Melanie Schellenberg ◽  
Janek Gröhl ◽  
Kris Dreher ◽  
Jan-Hinrich Nölke ◽  
...  

Abstract Purpose Photoacoustic tomography (PAT) is a novel imaging technique that can spatially resolve both morphological and functional tissue properties, such as vessel topology and tissue oxygenation. While this capacity makes PAT a promising modality for the diagnosis, treatment, and follow-up of various diseases, a current drawback is the limited field of view provided by the conventionally applied 2D probes. Methods In this paper, we present a novel approach to 3D reconstruction of PAT data (Tattoo tomography) that does not require an external tracking system and can smoothly be integrated into clinical workflows. It is based on an optical pattern placed on the region of interest prior to image acquisition. This pattern is designed in a way that a single tomographic image of it enables the recovery of the probe pose relative to the coordinate system of the pattern, which serves as a global coordinate system for image compounding. Results To investigate the feasibility of Tattoo tomography, we assessed the quality of 3D image reconstruction with experimental phantom data and in vivo forearm data. The results obtained with our prototype indicate that the Tattoo method enables the accurate and precise 3D reconstruction of PAT data and may be better suited for this task than the baseline method using optical tracking. Conclusions In contrast to previous approaches to 3D ultrasound (US) or PAT reconstruction, the Tattoo approach neither requires complex external hardware nor training data acquired for a specific application. It could thus become a valuable tool for clinical freehand PAT.


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