Space Tracking Research Articles

A study on recognizing multi-real world object and estimating 3D position in augmented reality

As augmented reality technologies develop, real-time interactions between objects present in the real world and virtual space are required. Generally, recognition and location estimation in augmented reality are carried out using tracking techniques, typically markers. However, using markers creates spatial constraints in simultaneous tracking of space and objects. Therefore, we propose a system that enables camera tracking in the real world and visualizes virtual visual information through the recognition and positioning of objects. We scanned the space using an RGB-D camera. A three-dimensional (3D) dense point cloud map is created using point clouds generated through video images. Among the generated point cloud information, objects are detected and retrieved based on the pre-learned data. Finally, using the predicted pose of the detected objects, other information may be augmented. Our system estimates object recognition and 3D pose based on simple camera information, enabling the viewing of virtual visual information based on object location.

Demonstration and verification experiment in deep space optical communications

In deep space optical communications, pointing, acquisition and tracking (PAT) system need to locate the position of the beacon, precisely. The way of employing the natural celestial body as the beacon come to draw attention, in contrast to regarding the laser as the beacon which has a series of problems of limited power, serious attenuation, high cost and difficult design realization. In this paper, the primary goal is to study the problem of precise positioning for the beacon by taking the natural celestial body as the beacon. Given the long distance, with small target and large uncertain region in deep space optical communications, the location of the beacon can be realized by the combination of rough and precise positioning based on the image feature of the beacon. Firstly, it performs the rough positioning according to the image characteristic information of the beacon’s edge, then in the uncertain region, the processing scope has been narrowed according the results of the rough positioning, finally the beacon is precisely located based on its minutiae feature by the way of feature point matching to achieve the position of the beacon. The impact due to the autorotation of celestial body on the image transform has been also discussed and analyzed with the mapping relationship of coordinate and geometric transform. The feasibility of the algorithm is verified by a long distance far-field Earth–Moon experiment. The design of system implementation on embedded hardware system can provide a reference for the real-time positioning system in deep space optical communications.

Railway Science: Results of the I International Scientific and Practical Conference “Research 1520 VNIIZHT: Look Beyond the Horizons”

In a constantly changing world, any production activity, including transport, requires scientific support, which, in turn, involves the active participation of scientists, as well as the possibility of exchanging views between theorists and practitioners. One of the most effective formats for this is a scientific conference, which allows discussing long-term trends in the development of the industry and ways of early adaptation to them. In the railway sector, scientific conferences have become a regular and effective tool for discussing promising trends in the industry.President of the Russian Federation Vladimir Putin declared 2021 the Year of Science and Technology. In this regard, it is symbolic that on August 26–27, 2021, the 1st International Scientific and Practical Conference “Science 1520 VNIIZHT: Look Beyond the Horizons” was held on the territory of Test Loop of the JSC “VNIIZHT”. The JSC Railway Research Institute, a leader in the development, creation, testing and implementation of railway equipment and technologies in the 1520 mm track space organized the conference. At the conference, reports were presented both by practitioners and acting managers, and by theoretical scientists. The conference was organized in the form of parallel working sections, the main results of which were discussed at a panel discussion. According to the presentation of the heads of the thematic sections, the best speakers were awarded with diplomas, including many young scientists. According to the assessments of managers and employees of railway enterprises and suppliers, the conference was a useful and longawaited international event in railway science and practice.

Teleportation in Virtual Reality; A Mini-Review

Teleportation is a widely implemented virtual locomotion technique that allows users to navigate beyond the confines of available tracking space with a low possibility of inducing virtual reality (VR) sickness. This paper provides a comprehensive overview of prior research on teleportation. We report results from user studies that have evaluated teleportation in comparison to other locomotion methods and survey improved versions of teleportation. We identify a number of areas for future research.

Stereovision for surveillance of Earth orbiting objects: Two methods and their validation with synthetic data

Due to the new trend of space economy and to the resulting increase of space objects, Space Surveillance and Space Traffic Management are becoming essential to reduce the risk of in-orbit collisions and of potential on Earth damages from uncontrolled re-entries. Ground based optical observations, where cameras are coupled with telescopes, represent an invaluable resource for space debris monitoring and tracking. Observations from one single site may provide angular celestial coordinates of a space object, but they must be supplemented with filters and astrodynamic models to provide an estimate of the object trajectory. An alternative approach is the use of multi-site optical observations, where images of the same portion of sky collected with different cameras are matched to retrieve the 3D instantaneous position of space objects without the need of a priori knowledge of the object orbit parameters. Therefore, multi-site observations are extremely convenient to track uncontrolled Earth re-entry and close approach, where the orbit parameters are generally not stable. Here we focus on two-cameras systems and we discuss the use of two triangulation methods: one based on analytic geometry, the other one based on projective geometry. As a proof-of-concept, we compare the performance of the two methods in terms of accuracy in the 3D reconstruction on synthetic images that reproduce the night sky – including orbiting objects and stars – from different locations. To simulate realistic data sets, we produced images taking into account the effect of refraction and annual aberration on the stars, and we added gaussian noise to the position of the stars and of the space objects on the images. The comparison between the two methods shows that they are both valuable, with the projective method being more robust against noise.

Radio astronomy and Space science in Azores: Enhancing the Atlantic VLBI infrastructure cluster

Radio astronomy and Space Infrastructures in the Azores have a great scientific and industrial interest because they benefit from a unique geographical location in the middle of the North Atlantic allowing a vast improvement in the sky coverage. This fact obviously has a very high added value for: i) the establishment of space tracking and communications networks for the emergent global small satellite fleets ii) it is invaluable to connect the radio astronomy infrastructure networks in Africa, Europe and America continents using Very Large Baseline Interferometry (VLBI) techniques, iii) it allows excellent potential for monitoring space debris and Near Earth Objects (NEOs). There is in S. Miguel island a 32-metre SATCOM antenna that could be integrated in advanced VLBI networks and be capable of additional Deep Space Network ground support. This paper explores the space science opportunities offered by the upgrade of the S. Miguel 32-metre SATCOM antenna into a world-class infrastructure for radio astronomy and space exploration: it would enable a Deep Space Network mode and would constitute a key space facility for data production, promoting local digital infrastructure investments and the testing of cutting-edge information technologies. Its Atlantic location also enables improvements in angular resolution, provides many baselines in East–West and North–South directions connecting the emergent VLBI stations in America to Europe and Africa VLBI arrays therefore contributing for greater array imaging capabilities especially for sources or well studied fields close to or below the celestial equator, where ESO facilities, ALMA, SKA and its precursors do or will operate and observe in the coming decades.

Optimal Rotating Receiver Angles Estimation for Multicoil Dynamic Wireless Power Transfer

This study proposed an approach to dynamic wireless charging that uses a rotating receiver coil. Our simulation study focused on the verification of a novel way of increasing the coupling coefficient and power transfer stability by following the flux of the transmitting coils. To obtain the highest possible coupling by means of the FEM analysis, we studied the optimization of the trajectory of the angular velocity of the rotating receiver. The coupling coefficient trajectories that were obtained were simulated by means of the state space model with three transmitters. Our comprehensive analysis showed that the proposed approach of wireless power transmission enabled a 40% increase in the usage of track space.

Event-based tracking of human hands

Purpose This paper proposes a novel method for human hands tracking using data from an event camera. The event camera detects changes in brightness, measuring motion, with low latency, no motion blur, low power consumption and high dynamic range. Captured frames are analysed using lightweight algorithms reporting three-dimensional (3D) hand position data. The chosen pick-and-place scenario serves as an example input for collaborative human–robot interactions and in obstacle avoidance for human–robot safety applications. Design/methodology/approach Events data are pre-processed into intensity frames. The regions of interest (ROI) are defined through object edge event activity, reducing noise. ROI features are extracted for use in-depth perception. Findings Event-based tracking of human hand demonstrated feasible, in real time and at a low computational cost. The proposed ROI-finding method reduces noise from intensity images, achieving up to 89% of data reduction in relation to the original, while preserving the features. The depth estimation error in relation to ground truth (measured with wearables), measured using dynamic time warping and using a single event camera, is from 15 to 30 millimetres, depending on the plane it is measured. Originality/value Tracking of human hands in 3 D space using a single event camera data and lightweight algorithms to define ROI features (hands tracking in space).

POSSIBILITIES OF SPATIAL CORRELATION OF 3D MODELS IN AN ARCHAEOLOGICAL AUGMENTED REALITY APPLICATION

Abstract. The use of Augmented Reality (AR) technology is widespread in countless archaeological sites and a variety of applications. Archaeological excavations lead to archaeological finds, some of which are transported for preservation and then for exhibition in museums (jewelry, vases, etc.), while another part of them is documented in detail and remains in situ (eg building walls), roads, grave covers, etc.). However, after the registration of the archaeological finds, it is impossible to observe them. As part of our research project, we will develop for the first time AR methodology and procedures for the observation of covered archaeological finds on mobile devices (smart phones, tablets), which were registered after their documentation. AR technology in recent years has seen great growth in terms of implementation platforms and available software, as well as the tools developed to support it. These tools either make their appearance in the form of frameworks, extending the capabilities of an existing engine, or function as independent services. At the same time, progress has been made in the field of sensors of mobile devices, which makes the compatibility of hardware and software another issue to be researched. As part of the development of the above application for mobile devices, an evaluation is made of the most widespread AR Frameworks that support the Unity3d Game Engine and the compatibility / interoperability with the sensors of different categories of mobile devices. The frameworks were checked and evaluated for placement and tracking of the positions of the 3D covered objects. In this paper also, methodologies and techniques used in space detection and tracking are presented and evaluated.

Distributed Model Predictive Longitudinal Control for a Connected Autonomous Vehicle Platoon with Dynamic Information Flow Topology

The development of vehicle-to-vehicle (V2V) improves the cooperation efficiency of the connected autonomous vehicle (CAV) platoon. However, the failure of the network communication occurs occasionally in the realistic environment, where the ideal fixed information flow topology (FIFT) cannot be adapted. To address this issue, this paper proposes a dynamic information flow topology (DIFT) utilizing a distributed model predictive control (DMPC) algorithm for CAV platoons. When the communication link is broken, the platoon control system will switch to the corresponding collaborative control mode instead of the degeneration to adaptive cruise control (ACC). First, the duty-vehicle dynamic model is constructed. In addition, the constraints with vehicle physical limitations and rear-end collision are considered. The acceleration information of the pedal actuator from the leading vehicle and the states of the predecessor including position, velocity and acceleration are transmitted to the following vehicle with a switch Indicator under DIFT. The cost function with the consideration of DIFT and fuel consumption is formulated for the optimization problem. Comparing with the FIFT, the proposed method is evaluated in the co-simulation of Matlab-TruckSim. The results demonstrate that the proposed DIFT strategy shows the satisfactory performance of the platoon under the communication issues by measuring inter-vehicle space, position and velocity tracking, and acceleration change with high tracking accuracy of position within 1.2 m and velocity within 0.04 m/s.

RETRACTED ARTICLE: Evaluation and research of comprehensive seismic observation technology based on optical fiber sensing

As one of the most important methods in geophysical exploration, seismic exploration is widely used in geological resource exploration, geological disaster early warning, and other fields. Existing seismic exploration instruments mostly use electromechanical geophones for sensing, and electromechanical geophones are point sensors. In oil and gas exploration and natural seismic monitoring, point sensors must be arrayed to ensure the continuity of the seismic wave distribution. There are problems such as difficult deployment and long-term maintenance, and its detection capacity and density are also limited by cost. Optical fiber is both a sensor and a transmission medium. A large number of sensor arrays can be realized by using optical fiber. In exploration applications, only one optical cable needs to be deployed or the existing communication optical cable is directly used, which is relatively low in difficulty and cost. Under the premise of ensuring high-level data and high-density acquisition, it can still achieve a detection length of tens of kilometers, which has important potential application value in the field of seismic exploration where exploration targets are increasingly deep and refined. The seismic prospecting instrument participated in a ground fissure state monitoring test based on an active source in a certain area. In the test, the existing buried and underground fiber optic cables were used to successfully monitor the seismic waves, and the monitoring track spacing reached 4 m; the output waveform that is consistent with the existing geophones is obtained, which shows a higher sensitivity than the existing geophones.

Simulation of gymnastics performance based on MEMS sensor

The development and progress of multi-sensor data fusion theory and methods have also laid the foundation for the research of human body posture tracking system based on inertial sensing. The main research in this paper is the simulation of gymnastics performance based on MEMS sensors. In the preprocessing to reduce noise interference, this paper mainly uses median filtering to remove signal glitches. This article uses virtual character models for gymnastics performances. The computer receives sensor data from the sink node of the motion capture device through a Bluetooth communication module. The unit calculates the quaternion output from the dynamic link library of sensor data processing, calculates the rotation amount and coordinate offset of each sensor node’s limb, and uses the character model to realize the real-time rendering of the virtual character model. At the same time, it controls the storage of sensor data, the drive of the model, and the display of the graphical interface. When a gesture action is about to occur, a trigger signal is given to the system to mark the beginning of the action, so as to obtain the initial data of each axis signal of the MEMS sensor. When the gesture action is completed, give the system a signal to end the action. Mark the end of the action, so that you can capture the original signal data during the beginning and end of the gesture action. In order to ensure the normal communication between PS and PL, it is necessary to test the key interfaces involved. Because the data received by the SPI acquisition module is irregular, it is impossible to verify whether the data is wrong, so the SPI acquisition module is replaced with a module that automatically increments data, and the IP core is generated, and a test platform is built for testing. The data shows that the average measurement error of X-axis displacement of the space tracking system is 8.17%, the average measurement error of Y-axis displacement is 7.51%, the average measurement error of Z-axis displacement is 9.72%, and the average error of three-dimensional space measurement is 8.7%. The results show that the MEMS sensor can accurately recognize the action with high accuracy.

Tracking and vibration control of a free-floating space manipulator system with flexible links and joints

The problem of modeling and controlling of a free-floating space manipulator with flexures in both links and joints is addressed in this study. A mathematical model of the system is developed by combining Lagrange’s equations and momentum conservation. The finite element method is introduced to discretize multi-links with complex cross-sections. In order to reduce the dimensions and maintain the precision of a rigid-flexible coupled system, an iterated improved reduction system method is adopted. Then, a novel composite control scheme for the reduced system is presented that uses the concept of integral manifolds and singular perturbation theory. Finally, an augmented computed torque controller is applied to the under-actuated slow subsystem to realize trajectory tracking in joint space, while a linear-quadratic controller is designed to damp out the vibration of joints and links. Numerical simulation results verified that the proposed hybrid controller can successfully suppress vibration and track trajectory at the same time.

A non-intrusive space-time interpolation from compact Stiefel manifolds of parametrized rigid-viscoplastic FEM problems

This work aims to interpolate parametrized reduced order model (ROM) basis constructed via the proper orthogonal decomposition (POD) to derive a robust ROM of the system’s dynamics for an unseen target parameter value. A novel non-intrusive space-time (ST) POD basis interpolation scheme is proposed, for which we define ROM spatial and temporal basis curves on compact Stiefel manifolds. An interpolation is finally defined on a mixed part encoded in a square matrix directly deduced using the spacial part, the singular values and the temporal part, to obtain an interpolated snapshot matrix, keeping track of accurate space and temporal eigenvectors. Moreover, in order to establish a well-defined curve on the compact Stiefel manifold, we introduce a new procedure, the so-called oriented SVD. Such an oriented SVD produces unique right and left eigenvectors for generic matrices, for which all singular values are distinct. It is important to notice that the ST POD basis interpolation does not require the construction and the subsequent solution of a reduced-order FEM model as classically is done. Hence it is avoiding the bottleneck of standard POD interpolation which is associated with the evaluation of the nonlinear terms of the Galerkin projection on the governing equations. As a proof of concept, the proposed method is demonstrated with the adaptation of rigid-thermoviscoplastic finite element ROMs applied to a typical nonlinear open forging metal forming process. Strong correlations of the ST POD models with respect to their associated high-fidelity FEM counterpart simulations are reported, highlighting its potential use for near real-time parametric simulations using off-line computed ROM POD databases.

Numerical algebraic geometry and semidefinite programming

Standard interior point methods in semidefinite programming can be viewed as tracking a solution path for a homotopy defined by a system of bilinear equations. By considering this in the context of numerical algebraic geometry, we employ numerical algebraic geometric techniques such as adaptive precision path tracking, endgames, and projective space to accurately solve semidefinite programs. We develop feasibility tests for both primal and dual problems which can distinguish between the four feasibility types of semidefinite programs. Finally, we couple our feasibility tests with facial reduction to develop a solving approach that can handle every scenario arising in semidefinite programming, including problems with nonzero duality gap. Various examples are used to demonstrate the new methods with comparisons to commonly used semidefinite programming software.

Burn-cycle-dependent spatial distribution of nuclear fuel actinides and fission products based on the AGENT code

BRITTS (Burnup of Reactor Isotopes, Tracking in Time and Space) is a newly developed burnup module based on the Runge-Kutta 4th order method supplementing the well-known AGENT neutronics code. Unlike other burnup codes that are limited to 2D models, cumulative-only calculations, or one specific fuel type, BRITTS provides detailed spatial distributions of actinides in 2D and approximate 3D (through a 2D/1D coupled characteristic solution provided by the AGENT code) at user-specified points in a burn cycle. Using two simple MOX fuel pins, BRITTS is compared with SCALE6.2. BRITTS is also compared against a well-known OECD/NEA benchmark of UO2 fuel pin with 16 participants. These comparisons show that BRITTS provides reliable calculations for concentrations of nuclear fuel actinides and fission products in both 2D and approximate 3D and can be uniquely used to analyze the spatial distributions of the actinides during the burn-cycles. This paper presents the mathematical and numerical methods employed in BRITTS and a series of benchmark examples showing the code capabilities for reactor fuel analyses.

Real-time implementation of fast discriminative scale space tracking algorithm

Real-time object tracking is an important step of many modern image processing applications. The efficient hardware design of real-time object tracker must achieve the desired accuracy while satisfying the frame rate requirements for a variety of image sizes. The existing methods of visual tracking employ sophisticated algorithms and challenge the capabilities of most embedded architectures. Discriminative scale space tracking is one algorithm that is capable of demonstrating good performance with affordable complexity. It has a high degree of parallelism which can be exploited for efficient implementation of reconfigurable hardware architectures. This paper proposes a real-time implementation of the discriminative scale-space tracker on FPGA for the major blocks. A careful design exploration of core mathematical operations of the tracking algorithm is performed to improve their hardware utilization and timing performance. Among the core functional units optimized in this work, the discrete Fourier transform achieves a computational time improvement of 92% relative to existing works, QR factorization achieves a 2.3times reduction in resource utilization, and singular value decomposition yields a 3.8times improvement in processing time. The proposed data path architecture is designed using Vivado HLS tool set and implemented for Zync Zed Board (xc7z020clg484-1). For an input image size of 320 times 240, the proposed architecture achieves a mean 25.38 fps.

Performance of a U-Net-based neural network for predictive adaptive optics.

We apply a U-Net-based convolutional neural network (NN) architecture to the problem of predictive adaptive optics (AO) for tracking and imaging fast-moving targets, such as satellites in low Earth orbit (LEO). We show that the fine-tuned NN is able to achieve an approximately 50% reduction in mean-squared wavefront error over non-predictive approaches while predicting up to eight frames into the future. These results were obtained when the NN, trained mostly on simulated data, tested its performance on 1 kHz Shack-Hartmann wavefront sensor data collected in open-loop at the Advanced Electro-Optical System facility at Haleakala Observatory while the telescope tracked a naturally illuminated piece of LEO space debris. We report, to our knowledge, the first successful test of a NN for the predictive AO application using on-sky data, as well as the first time such a network has been developed for the more stressing space tracking application.

PSOAS ABSCESS – THE CHANGING TRENDS

Introduction: Psoas abscess (IPA) is an abscess collection in the retroperitoneal space tracking along the psoas major muscle. The microbial etiology of Psoas abscess is variable and depends on the geographical area. This study attempts to evaluate the microbial etiology, its implication in deciding the management modalities, and outcomes in patients with Psoas abscess from a tertiary care center in South India.
 Materials and Methods: This was a retrospective study done in a tertiary care center in Southern India. Results: A total of 47 patients were enrolled in the study, with causative organism identified in 40 (85.15%) patients. In 17 patients (36.17%), it was found to be tuberculous origin; and of nontuberculous origin in 23 patients (48.93%). No causative organism could not be isolated in 7 patients (14.89%). While 33 patients were treated with percutaneous drainage (70.12%), open drainage was done in 14 patients (29.78%) and 1 patient died (2.12%).
 Conclusion: The most common causative organism of psoas abscess is found to be of nontuberculous origin and PCD was found to be better modality of treatment. Empirical administration of anti-tuberculous drugs needs further evaluation.
 Key words: psoas, retroperitoneal, retrospective, tuberculous, drainage, empirical

Recent developments in the implementation of European Space Surveillance & Tracking (EU SST)–Security and data policy

European Space Surveillance & Tracking (EU SST) is the European Union's operational capability for safeguarding space infrastructure and contributing to global burden-sharing in the domain of Space Situational Awareness (SSA). Implemented by a Consortium of EU member states in cooperation with the EU Satellite Centre, EU SST today serves over 100 user organizations with free services, such as Collision Avoidance for over 210 satellites. The Consortium operates a growing sensor network of radars, telescopes and lasers, which remain under the authority of the member states, reflecting the dual dimension of the SSA domain. Measurements and orbit data from the contributing sensors are shared through a dedicated platform, the EU SST Database.As the Consortium increasingly shares data through the Database on a daily basis and will be processing that data into a European catalogue precursor, the Consortium's internal Security Committee is responsible for further developing the EU SST data policy that must balance the requirements for transparency and safety of flight with security constraints linked to precise and timely information on the nature, specifications and location of certain space objects.This article reports on recent developments in the implementation of EU SST with regard to security and data policy. It highlights the unique governance and data sharing model of EU SST, the diverse architecture of existing SSA sharing agreements, and data security considerations.