Earth Sensor Research Articles

Attitude Determination Algorithm Using Earth Sensor Images and Image Recognition

This paper describes a new algorithm to determine the attitude of micro-/nano-satellites using an Earth sensor. For recent micro-/nano-satellites, the requirements for attitude determination accuracy are becoming more stringent, despite its limited volume. Since Earth sensors have the advantage of smaller size, some studies have presented using them as attitude sensors; however, they could not achieve fully automatic processing in real-time. Therefore, we have developed an algorithm that effectively combines geometrical consideration and image recognition technology, thus realizing high autonomy, robustness, and real-time processing. The validity of this algorithm is confirmed through ground experiments. The algorithm operates at a rate of 0.2 Hz and achieves an accuracy of 0.1–1 deg, which is similar to the accuracy of a coarse sun sensor. Furthermore, it is capable of determining the three-axis attitude using only an Earth sensor and a GNSS receiver for position information. This study proves that the bus equipment required for attitude determination systems in micro-/nano-satellites can be reduced, thereby contributing to increased design freedom.

On-board Relative Attitude Determination and Propagation Using Earth Sensor

In this paper, we propose methods to determine and propagate relative attitude using an earth sensor. Three-axis attitude determination using the Earth sensor is advantageous in terms of space consumption, but it is a fault that we cannot always use it. By detecting and propagating relative attitude information, we attempt to fill that time gaps. The difficulty is that the spacecraft cannot ignore its own translational movement when it looks at the earth, unlike when it looks at the stars. In this research, the attitude and position estimation method used in computer vision is applied instead of the traditional attitude determination method for spacecrafts used in STT and so on. The algorithms use the movement of a point common to two images taken with a time interval, and the translational movement information of the spacecraft obtained from orbit information. The obtained relative attitude is propagated using a Kalman filter to estimate the absolute attitude. The proposed algorithms are evaluated by numerical simulations. The results are as accurate as small MEMS gyro sensors, suggesting the possibility of being replaceable in the future.

Visual Study of Multi-Dimensional Data in Remote Earth Sensing Problems

The article deals with the problem of multidimensional data presentation based on the application of the scientific visualization method. A method of visual-interactive animation based on dynamic representation of images in the form of 2D cross-sectional models is proposed. The effect of multidimensionality is achieved through the choice of 2D models, the variability of the directions of dynamic sections and the use of stereoscopic vision capabilities.

Exploring planets and asteroids with 6DoF sensors: Utopia and realism

A 6 degrees-of-freedom (6DoF) sensor, measuring three components of translational acceleration and three components of rotation rate, provides the full history of motion it is exposed to. In Earth sciences 6DoF sensors have shown great potential in exploring the interior of our planet and its seismic sources. In space sciences, apart from navigation, 6DoF sensors are, up to now, only rarely used to answer scientific questions. As a first step of establishing 6DoF motion sensing deeper into space sciences, this article describes novel scientific approaches based on 6DoF motion sensing with substantial potential for constraining the interior structure of planetary objects and asteroids. Therefore we estimate 6DoF-signal levels that originate from lander–surface interactions during landing and touchdown, from a body’s rotational dynamics as well as from seismic ground motions. We discuss these signals for an exemplary set of target bodies including Dimorphos, Phobos, Europa, the Earth’s Moon and Mars and compare those to self-noise levels of state-of-the-art sensors.

Rare earth doped metal oxide sensor for the multimodal detection of volatile organic compounds (VOCs)

Heated metal oxide sensors have been widely studied for their ability to give a reversible change in the electrical resistance following the interaction with a volatile compound. Another feature is their inherent cataluminescence (CTL) properties when these materials interact with specific volatiles.This study reports for the first time a zirconium oxide nanomaterial doped with a rare earth metal which gives combined resistance and cataluminescence responses, providing enhanced sensitivity and selectivity of detection via a multimodal response in a single sensor. The europium-doped zirconium oxide, ZrO2:Eu3+ was studied and compared with the undoped zirconium oxide, ZrO2, and tungsten oxide, WO3. Materials were characterised structurally and tested with a series of volatiles. Both the cataluminescence light emission and the resistance response were recorded at different temperatures (starting from 180 °C up to 400 °C) and then combined to achieve the dual modality response. Europium-doped zirconium oxide gave a better sensitivity in terms of cataluminescence response than the undoped zirconium oxide sensor; dual modality sensing is demonstrated for ethanol and acetone which give cataluminescence and resistance responses on both the undoped and europium doped zirconia.

Remote Sensing of Ecosystem Structure: Fusing Passive and Active Remotely Sensed Data to Characterize a Deltaic Wetland Landscape

A project was constructed to integrate remotely sensed data from multiple sensors and platforms to characterize range of ecosystem characteristics in the Peace–Athabasca Delta in Northern Alberta, Canada. The objective of this project was to provide a framework for the processing of multisensor data to extract ecosystem information describing complex deltaic wetland environments. The data used in this study was based on a passive satellite-based earth observation multispectral sensor (Sentinel-2) and airborne discrete light detection and ranging (LiDAR). The data processing strategy adopted here allowed us to employ a data mining approach to grouping of the input variables into ecologically meaningful clusters. Using this approach, we described not only the reflective characteristics of the cover, but also ascribe vertical and horizontal structure, thereby differentiating spectrally similar, but ecologically distinct, ground features. This methodology provides a framework for assessing the impact of ecosystems on radiance, as measured by Earth observing systems, where it forms the basis for sampling and analysis. This final point will be the focus of future work.

Physical modeling of buried PVC pipes overlying localized ground subsidence

The last half-century has witnessed a proliferation in the use of polyvinyl chloride (PVC) pipes in civil engineering applications. However, little physical data are available to date to assess conformance with performance limits of these pipes subjected to events involving localized ground subsidence. In this study, experimental results are generated and evaluated from a series of physical models involving a buried PVC pipe overlying a localized subsiding bedding zone. Ground subsidence was simulated using a precisely controlled trapdoor system positioned at mid-length of the pipe. A technique including the use of a custom-made displacement transducer was developed as part of this study to facilitate collection of continuous deflection profiles along the axis of the pipes. The progressive development of soil arching was also monitored using earth pressure sensors placed on the top, sides, and at several locations beneath the pipe, both within and beyond the zone of ground subsidence. Strains in the external wall of the pipe were also monitored. The results indicate that significant bending developed in the portion of the pipe traversing the subsidence zone, especially at the pipe crown. Beyond this point, radial deflections of the pipe cross section continued to be detected along the pipe length to distances of approximately four pipe diameters. Ground subsidence induced a severe redistribution of the earth pressures measured in the soil mass surrounding the pipe. A significant increase in vertical soil pressures beneath the pipe was captured within a distance of about one pipe diameter outside the subsidence zone. The overall response of the PVC pipe to localized ground subsidence was found to improve with increasing backfill density and decreasing soil confinement.

Infrared Earth sensor with a large field of view for low-Earth-orbiting micro-satellites

Infrared Earth sensors are widely used in attitude-determination and control systems of satellites. The main deficiency of static infrared Earth sensors is the requirement of a small field of view (FOV). A typical FOV for a static infrared Earth sensor is about 20° to 30°, which may not be sufficient for low-Earth-orbiting micro-satellites. A novel compact infrared Earth sensor with an FOV of nearly 180° is developed here. The Earth sensor comprises a panoramic annular lens (PAL) and an off-the-shelf camera with an uncooled complementary-metal-oxide-semiconductor (CMOS) infrared sensor. PAL is used to augment FOV so as to obtain a complete infrared image of the Earth from low-Earth-orbit. An algorithm is developed to compensate for the distortion caused by PAL and to calculate the vector of the Earth. The new infrared Earth sensor is compact with low power consumption and high precision. Simulated images and on-orbit infrared images obtained via the micro-satellite ZDPS-2 are used to assess the performance of the new infrared Earth sensor. Experiments show that the accuracy of the Earth sensor is about 0.032°.

Micro-Infrared Thermopile Detector Space Applications Based on FPGA

Infrared earth sensors are an important attitude measurement component of satellite control subsystems.They provide the information about the satellite’s attitude relative to the pitch and roll direction of the earth radiation disk.The infrared detector is the key part of such a sensor.In this paper,we discuss research on micro-infrared thermopile detectors for space applications.Infrared thermopile technology and the technical index of the detector are introduced.The ring effect,temperature compensation,response compensation,nonuniformity correction,and blind element processing of the detector are studied.The scheme design and field programmable gate array(FPGA)design of an infrared earth sensor image processing system are described.Test results show that system’s attitude measurement deviation is less than 0.2°.Thus,FPGA-based micro-infrared thermopile detectors based on FPGA can be used for attitude measurement in low earth orbit satellites.Offering miniaturization,low power consumption,and low cost,this technology has the potential to replace traditional mechanical scanning infrared earth sensors and has broad application prospects.

Classification of Oil Slicks and Look-Alike Slicks: A Linear Discriminant Analysis of Microwave, Infrared, and Optical Satellite Measurements

We classify low-backscatter regions observed in Synthetic Aperture Radar (SAR) measurements of the surface of the ocean as either oil slicks or look-alike slicks (radar false targets). Our proposed classification algorithm is based on Linear Discriminant Analyses (LDAs) of RADARSAT-1 measurements (402 scenes off the southeast coast of Brazil from July 2001 to June 2003) and Meteorological-Oceanographic (MetOc) data from other earth observation sensors: Advanced Very High Resolution Radiometer (AVHRR), Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), Moderate Resolution Imaging Spectroradiometer (MODIS), and Quick Scatterometer (QuikSCAT). Oil slicks are sea-surface expressions of exploration and production oil, ship- and orphan-spills. False targets are associated with environmental phenomena, such as biogenic films, algal blooms, upwelling, low wind, or rain cells. Both categories have been interpreted by domain-experts: mineral oil (n = 350; 45.5%) and petroleum free (n = 419; 54.5%). We explore nine size variables (area, perimeter, etc.) and three types of MetOc information (sea surface temperature, chlorophyll-a, and wind speed) that describe the 769 samples analyzed. Seven attribute–domain combinations are tested with three non-linear transformations (none, cube root, log10), with and without MetOc, adding to 39 attribute subdivisions. Classification accuracies are independent of data transformation and improve when selected size attributes are combined with MetOc, leading to overall accuracies of ~80% and sound levels of sensitivity (~90%), specificity (~80%), positive (~80%) and negative (~90%) predictive values. The effectiveness of this data-driven attempt supports further commercial or academic implementation of our LDA algorithm.

Fabrication of Advanced Agribot Robot

Numerous nations in Asia including India are agrarian economies and the majority of their rustic populaces rely upon horticulture to acquire their business. The utilization of apparatuses and domesticated animals in the rural procedure has decreased the human exertion. Central point that influence agribusiness incorporate less holding territory, deficiency of seeds, manures and work and vulnerability of storm. The motorization of horticulture alludes to the utilization of devices or machines in the rural procedure that conceivably lessens the human exertion. In spite of the fact that it lessens the human exertion in the horticultural procedure, it requires total human collaboration. The mechanization and apply autonomy application in the part of agribusiness is at the blasting stage when contrasted with its wide scope of use in different divisions. Numerous inquires about have been done in this field to robotize the procedure. In the current paper an exertion is made for the plan and advancement of the robot that can perform seeding process with no human intercession. The robot created is equipped for causing a gap in the dirt to up to certain profundity, putting the seed precisely in a similar gap and shutting the mud. The procedure is constrained by a microcontroller. The robot created defeats the disadvantages in the customary technique for seeding which incorporates wastage of seeds, high work wage, lower use of land and so forth. By the utilization of computerization and mechanical technology in the field of farming it is conceivable to build the general proficiency of the agrarian procedure and can alleviate impacts of work lack. This paper likewise presents the IoT-based horticultural creation framework for balancing out organic market of rural items while building up the earth sensors and expectation framework for the development and creation measure of yields by social affair its ecological data. As of now, the interest by utilization of horticultural items could be anticipated quantitatively, be that as it may, the variety of reap and creation by the difference in homestead's developed zone, climate change, infection and bug harm and so on. Couldn't be anticipated, so the market interest of agrarian items has not been controlled appropriately. To beat it, this paper structured the IoT-based checking framework to dissect crop condition, and the technique to improve the effectiveness of dynamic by investigating harvest measurements.

Integrated celestial navigation for spacecraft using interferometer and Earth sensor

An integrated celestial navigation scheme for spacecrafts based on an optical interferometer and an ultraviolet Earth sensor is presented in this paper. The optical interferometer is adopted to measure the change in inter-star angles due to stellar aberration, which provides information on the velocity of the spacecraft in the plane perpendicular to the direction of the observed star. In order to enhance the navigation performance, the measurements obtained from the ultraviolet Earth sensor is used to eliminate the unfavorable effect caused by the gravitational deflection of starlight. As the prior knowledge about the optical path delay bias of the optical interferometer may be ambiguous, a Q-learning extended Kalman filter is derived to fuse the two types of measurements, and estimate the kinematic state together with the optical path delay bias. The solution of the autonomous navigation system consists of position, velocity and attitude of the spacecraft. Numerical simulation shows that an evident improvement in navigation accuracy can be achieved by introducing the ultraviolet Earth sensor into the navigation system. In addition, it is shown that the Q-learning extended Kalman filter performs better than the traditional extended Kalman filter.

Design of indoor model test system for Post-stiffened core lengthened concrete pile

The post-stiffened core lengthened concrete pile is a kind of composite foundation pile formed after the existing concrete core is inserted into the stiffened core lengthened body through the hole. Based on the pile-forming technology and testing needs of the pile structure, a set of indoor model test system is studied and determined. The system is mainly composed of model groove, loading system and measuring system, and the setting of post-stiffening core section can be realized by controlling the filling time of concrete in the existing concrete core position. The displacement test body is set up on the top of the model pile and the soil around the pile, the stress sensor is set in the pile body and the core body, and the earth pressure sensor is set in the soil around the pile. The test system can form the bearing capacity of pile body (including existing concrete pile and stiffening core section) and soil around the pile from multiple dimensions, and realize the test of pile response under different load combinations by controlling the loading process.

A Model Test for the Influence of Lateral Pressure on Vertical Bearing Characteristics in Pile Jacking Process Based on Optical Sensors.

Photoelectric integrated testing technology was used to study precast piles during pile jacking at the pile–soil interface considering the influence of the earth and pore water pressures on its vertical bearing performance. The low temperature sensitive fiber Bragg grating (FBG) strain sensors and miniature silicon piezoresistive sensors were implanted in the model pile to test the changes of earth pressure, pore water pressure and pile axial force of the jacked pile at the pile–soil interface, and the influence of lateral pressure on pile axial force was studied. The test results showed that the nylon rod is feasible as a model pile. The FBG strain sensor had a stable performance and monitored changes in the axial force of the model pile in real time. The miniature earth and pore water pressure sensors were small enough to avoid size effects and accurately measured changes in the earth and pore water pressures during the pile jacking process. During pile jacking, the lateral earth pressure increased gradually in depth, and the lateral earth pressure at the same depth tended to decrease at greater depths. Lateral pressures caused the axial force of the pile to increases by a factor of 1–2, where the maximum was 2.7. Therefore, the influence of the lateral pressure must be considered when studying the residual pile stress.

PACO: Python-Based Atmospheric COrrection.

The atmospheric correction of satellite images based on radiative transfer calculations is a prerequisite for many remote sensing applications. The software package ATCOR, developed at the German Aerospace Center (DLR), is a versatile atmospheric correction software, capable of processing data acquired by many different optical satellite sensors. Based on this well established algorithm, a new Python-based atmospheric correction software has been developed to generate L2A products of Sentinel-2, Landsat-8, and of new space-based hyperspectral sensors such as DESIS (DLR Earth Sensing Imaging Spectrometer) and EnMAP (Environmental Mapping and Analysis Program). This paper outlines the underlying algorithms of PACO, and presents the validation results by comparing L2A products generated from Sentinel-2 L1C images with in situ (AERONET and RadCalNet) data within VNIR-SWIR spectral wavelengths range.

Design and analysis of attitude control algorithm for low earth orbiting satellite with magnetic torquer concepts using nonlinear unscented Kalman filter

Attitude control system plays the important role for to maintain the satellite to desired orientation. To control the satellite it is necessary to do the attitude stabilization. Attitude stabilization achieved by Star sensor, sun sensor, Earth sensors. Attitude control is mainly use for antenna pointing accuracy, camera focus to earth surface and solar panel pointing toward sun. Due to tumbling effects, satellite will rotate all the direction in the space. To maintain the orientation of the satellite it is necessary to design the attitude determination and control. Satellite consider as the rigid body. Inertia matrix describes the rigid body dynamics. The orientation of the satellite determine by Euler angle and Quaternion. The Low earth orbiting satellite will have enormous amount of aerodynamic drag stinking the satellite body and gravitational attraction another problem. Because of that satellite dwell, time is reduced. It means satellite more time spending particular part of the earth. The attitude estimation is measures by the orientation of vectors. Attitude estimation means to find the position and orientation of flying object with respect to the fixed reference of reference. Vector remains considered in the frame of reference to compute for find the orientation of the body of the satellite in the inertial reference system. The Earth is an inertial reference frame, and Satellite is a body frame. Attitude sensor used to measure the satellite orientation in the reference frame. This will help in accurately predicting the orbit deviation and a control system to correct if any by providing the satellite momentum means ‘mass in motion’ changes in a body rapidly in Low earth orbit due to centripetal force acting on a satellite. Attitude control system (ACS) need the numerical simulation to find the required torque demand by the help of difference between reference input (Attitude) signal and feedback signal measure by attitude sensor to trim the control surface maintain the actuator required orientation . The results will consist of two parts the first part consisting of the attitude estimation using Euler angle and Quaternion method, second part consist of estimate the control torque from magnetic torquer and error estimation using non-linear filter (Unscented Kalman Filter) with MATLAB simulation. Â

Итоги и особенности Восемнадцатой Всероссийской открытой конференции с международным участием «Современные проблемы дистанционного зондирования Земли из космоса»

Итоги и особенности Восемнадцатой Всероссийской открытой конференции с международным участием «Современные проблемы дистанционного зондирования Земли из космоса»

Ecological risks of a steppe nature management: detection, classification and ways to overcome them (on the example of the Orenburg region)

The aim of the study is to reveal and classify ecological risks for steppe nature management as well as to suggest the ways to overcome them. The following methods were used: historical, cartographical, logic and field landscape researches, Earth Sensing data, the author's method of an expert ecological-economical assessment of steppe etalons and secondary steppes. The main ecological risks making influence on the condition of steppe land and biological resources are detected and classified for an agrarian and industrially developed steppe region. The conception of an “antiecological” framework is developed. The system of the most substantial risks is highlighted, recommendations to minimize these risks are offered.

Effects of Solar Invasion on Earth Observation Sensors at a Moon-Based Platform

The solar invasion to an Earth observation sensor will cause potential damage to the sensor and reduce the accuracy of the measurements. This paper investigates the effects of solar invasion on the Moon-based Earth observation sensors. Different from the space-borne platform, a Moon-based sensor can be equipped anywhere on the near-side of the Moon, and this makes it possible to reduce solar invasion effects by selecting suitable regions to equip sensors. In this paper, methods for calculating the duration of the Sun entering of the sensor’s field of view (FOV) and the solar invasion radiation at the entrance pupil of the sensor are proposed. By deducing the expressions of the proposed geometrical relationship between the Sun, Earth, and Moon-based platform, it has been found that the key parameter to the effects of solar invasion is the angle between the Sun direction and the line-of-sight vector. Based on this parameter, both the duration and radiation can be calculated. In addition, an evaluation approach based on the mean value and standard deviation has been established to compare the variation of solar invasion radiation at different positions on the lunar surface. The results show that the duration is almost the same wherever the sensor is placed in the permanent Earth-observation region. Further, by comparing the variation of solar invasion radiation at different positions on the near-side of the Moon, we suggest that equipping sensors on the mid–high latitude regions within the permanent Earth-observation region will result in less solar invasion affects.

INS/CNS navigation system based on multi-star pseudo measurements

In the integrated navigation of Inertial Navigation Systems (INS) and Celestial Navigation Systems (CNS), small stellar angular distances in a single field-of-view (FOV) star sensor lead to inaccurate navigation parameter estimations. A novel, INS/CNS integrated navigation system based on multi-star pseudo measurements is proposed in this paper. First, according to the identified navigation star's observation information, five candidate stars are directly selected from the Smithsonian Astrophysical Observatory (SAO) star catalog as those most favorable for estimating the probe position. Then, in addition to the identified navigation star's measurement, the five candidate stars' pseudo observation information are estimated to supplement the measurements. Finally, the INS/CNS integrated navigation system in the tightly coupled mode estimates the probe position with high accuracy utilizing the available measurement and pseudo measurements. The simulation results illustrate that, compared to the traditional INS/CNS integrated navigation system which uses the infrared Earth sensor to assist in measuring the celestial measurements of navigation stars in the star image, and the improved method which directly supplements the position measurement by the infrared Earth sensor, the proposed method markedly improves the positioning accuracy, while the three methods' total computational efficiencies including measurement acquisition and filtering are effectively the same.