Geographic Coordinate System Research Articles

Free, open, quantitative and adaptable digital soil map data and database for Nigeria.

Nigeria's digital soil map (DSM) and database is the most comprehensive and detailed source of quantitative information on the country's soil distribution. Digital cartography and geographic information system (GIS) operations were methods used in producing the DSM and database. We obtained analogue soil data in 8 hard copy maps (each at a displayable scale of 1: 650,000) from the Federal Department of Agricultural Land Resources (FDALR), which archived the result of Nigeria's reconnaissance soil survey. The survey started in 1985 and by 1990; it has completed the compilation of hard copy maps that outline Nigeria's major soil distribution. Our experimental design begins with electronic scanning of these paper maps. We set the scanning system to 500 dpi, creating high-resolution raster images, which were imported into ESRI ArcGIS software, for orthorectification by geo-referencing to WGS 1984 geographic coordinate system. We applied a spatial processing tool on the orthorectified images and created a geometrically-seamless mosaicked raster image for the soil data of the whole Nigeria. Using GIS on-screen digitization – with optimal snapping tolerance – we created vector polygons (spatial data) of soil components (mapping units). Finally, we coded the metadata (attributes) of Nigeria's soil distribution into Microsoft EXCEL spreadsheet, which we linked to the soil spatial data. The combined spatial and attribute soil data forms the soil database for Nigeria and provides, on-demand, vital soil information, such as thematic maps of soil characteristics. The department of Geoinformatics and surveying University of Nigeria, Enugu Campus (UNEC) is the major repository of Nigeria's DSM and database.

The background model of the medium energy X-ray telescope of Insight-HXMT

The Medium Energy X-ray Telescope (ME) is one of the main payloads of the Hard X-ray Modulation Telescope (dubbed as Insight-HXMT). The background of Insight-HXMT/ME is mainly caused by the environmental charged particles and the background intensity is modulated remarkably by the geomagnetic field, as well as the geographical location. At the same geographical location, the background spectral shape is stable but the intensity varies with the level of the environmental charged particles. In this paper, we develop a model to estimate the ME background based on the ME database that is established with the two-year blank sky observations of the high Galactic latitude. In this model, the entire geographical area covered by Insight-HXMT is divided into grids of 5°×5° in geographical coordinate system. For each grid, the background spectral shape can be obtained from the background database and the intensity can be corrected by the contemporary count rate of the blind FOV detectors. Thus the background spectrum can be obtained by accumulating the background of all the grids passed by Insight-HXMT during the effective observational time. The model test with the blank sky observations shows that the systematic error of the background estimation in 8.9−44.0 keV is ∼1.3% for a pointing observation with an average exposure ∼5.5 ks. We also find that the systematic error is anti-correlated with the exposure, which indicates the systematic error is partly contributed by the statistical error of count rate measured by the blind FOV detectors.

Behavior of Broadcast Ionospheric-Delay Models from GPS, Beidou, and Galileo Systems

Abstract The GNSS observations suffer from different types of errors that could affect the achieved positioning accuracy based on the receiver type used. Single-frequency receivers are widely used worldwide because of its low cost. The ionospheric delay considers the most challenging error for single-frequency GNSS observations. All satellite navigation systems, except GLONASS, are advising their users to correct for the ionospheric delay using a certain model. Those models’ coefficients are sent to users in the system’s navigation message. These models are different in their accuracy and behavior based on its foundation theory as well as the updating rate of their coefficients. The GPS uses Klobuchar model for mitigating the ionospheric delay. BeiDou system (BDS-2) adopts a slightly modified Klobuchar model that resembles GPS ICA (Ionospheric Correction Algorithm) with eight correction parameters but is formulated in a geographic coordinate system with different coefficients in origin and updating rate. Galileo system uses a different model (NeQuick model). This article investigates the behavior of the three models in correcting the ionospheric delay for three stations at different latitudes during 3 months of different states of ionospheric activity, comparing with International GNSS Service-Global Ionospheric Maps (IGS-GIMs). It is advised from this research’s outputs to use the GPS model for mitigating the ionospheric delay in low-latitude regions during the state of low-and medium-activity ionosphere. It is advised to use the BeiDou model for mitigating the ionospheric delay in mid-latitude regions during different states of ionospheric activity. It is advised to use the Galileo model for mitigating the ionospheric delay in high-latitude regions during different states of ionospheric activity. Also, the Galileo model is recommended for mitigating the ionospheric delay for low-latitude regions during the state of high-activity ionosphere.

Алгоритмы и конфигурация системы ориентации подвижных объектов на микромеханических чувствительных элементах

Inertial systems for attitude control, stabilisation and navigation of moving objects boast a range of unique qualities, the most important of which are autonomy and interference immunity. At present, strap-down inertial navigation systems using inexpensive and compact microelectromechanical sensors are popular. The biggest disadvantage of the attitude control systems utilising microelectromechanical sensors is rapid error accumulation over time. The main error sources in strap-down inertial navigation systems are the errors of angular velocity sensors and accelerometers. Currently the accuracy required is ensured by the attitude control system processing the following two signals simultaneously: the magnetometer signal and the signal received from global navigation satellite systems such as GPS (NAVSTAR) and/or GLONASS. We developed an unconventional approach to integrating the two systems, that is, a strap-down inertial navigation system and a global navigation satellite system. It involves using the difference between the accelerations computed according to the global navigation satellite systems and those computed by the acelerometers and transformed to the geographic coordinate system for evaluating and compensating for the error of attitude angle assessment via the kinematic channel. Since this approach does not use integration of accelerometer readings, the attitude angle errors at the initial stage do not accumulate over time. Numerical simulation results of the algorithms developed show that the attainable attitude angle estimation accuracy significantly exceeds the accuracy of conventional methods

Background model for the high-energy telescope of Insight-HXMT

Accurate background estimation is essential for spectral and temporal analysis in astrophysics. In this work, we construct the in-orbit background model for the High-Energy Telescope (HE) of the Hard X-ray Modulation Telescope (dubbed as Insight-HXMT). Based on the two-year blank sky observations of Insight-HXMT/HE, we first investigate the basic properties of the background and find that both the background spectral shape and intensity have long-term evolution at different geographical sites. The entire earth globe is then divided into small grids, each with a typical area of 5×5 square degrees in geographical coordinate system. For each grid, an empirical function is used to describe the long-term evolution of each channel of the background spectrum; the intensity of the background can be variable and a modification factor is introduced to account for this variability by measuring the contemporary flux of the blind detector. For a given pointing observation, the background model is accomplished by integrating over the grids that are passed by the track of the satellite in each orbit. Such a background model is tested with both the blank sky observations and campaigns for observations of a series of celestial sources. The results show an average systematic error of 1.5% for the background energy spectrum (26–100 keV) under a typical exposure of 8 ks, and <3% for background light curve estimation (30–150 keV). Therefore, the background model introduced in this paper is included in the Insight-HXMT software as a standard part specialized for both spectral and temporal analyses.

Trying to Identify some Ancient Residences in Albania through Old Maps

This paper attempts to identify ancient settlements in Albania by cartographic methods by elaborating geographical coordinates obtained from Ptolemy's work. The results of the paper are of interest for archeology, history, geography, geodesy, photogrammetry etc. The problem addressed is not simple, as for some settlements, different literature sources give different values ​​of geographical coordinates. In this context, those geographic coordinate systems that best deal with the real position of these settlements are selected. Thus, for example, the longitude (L) of Ohrid (which serves as a support point), in some sources is given the value L1 = 46040 ', while in later sources it is given the value L2 = 470 40'. The calculations are performed for both cases of this longitude, but greater certainty is given when L2 = 47040 'is obtained, because the geographical longitude of Skopje (Scupi with L = 48030'), Prishtina (Ulpiana, with L = 48040 '), Peja (Siparantum, with L = 46030'), etc., are closer to reality than L = 46040 ', according to which Ohrid appears to be highly displaced to the west, in relation to the aforementioned sites (pic. 2.1). Consequently, settlements located in and near the Apollo - Orikum-Ohrid triangle are identified with other sites (as noted in the following statements). All of these anomalies and others such as these have been handled carefully and according to a logical rationale for the material being processed, taking into account all factors that positively impact the settlement identification process.

Integrated navigation approaches of vehicle aided by the strapdown celestial angles

The integrated navigation method based on star sensor celestial angles (altitude angle and azimuth angle) is proposed to serve the need for rapidly responsive, reliable, and precise of a hypersonic vehicle under a sophisticated environment. An integrated navigation algorithm suitable for large azimuth misalignment is established under launching point inertial coordinate and local geographical coordinate system based on altitude angle and azimuth angles. Meanwhile, a Bayesian method for data dropouts aided by the strapdown celestial angles is presented for the rapid variability in the celestial star angle with active galaxies. A nonlinear Bayesian filter is applied to implement the simulation on account of the nonlinear feature of the state and measurement equations. The simulation results showed that the Bayesian method for integrated navigation data dropouts could be accomplished by altitude angle and azimuth angle aiding in both launching point inertial coordinate and local geographical coordinate systems, which converge to 1′ in 10 s. The method indicated that the integrated navigation significant errors derived from initial localization and initial attitude alignment could be modified by the strapdown inertial navigation system (SINS) supported by the star sensor’s celestial angle in the local geographic coordinate system in the early launch stage. For the seconds of the flight phase, the integrated navigation aided by celestial angles in the launching point inertial coordinate system was guaranteed for the feasibility and validity. During the flight, the feasibility and validity of integrated navigation were guaranteed aided by celestial angles in launching point inertial coordinate system.

Fine‐Scale Visualization of Aurora in a Wide Area Using Color Digital Camera Images From the International Space Station

AbstractThe full‐color photographs of aurora have been taken with digital single‐lens reflex cameras mounted on the International Space Station (ISS). Since these photographs do not have accurate time and geographical information, in order to use them as scientific data, it is necessary to calibrate the imaging parameters (such as looking direction and angle of view of the camera) of the photographs. For this purpose, we calibrated the imaging parameters using a city light image taken from the Defense Meteorological Satellite Program satellite following the method of Hozumi et al. (2016, https://doi.org/10.1186/s40623-016-0532-z). We mapped the photographs onto the geographic coordinate system using the calibrated imaging parameters. To evaluate the accuracy of the mapping, we compared the aurora taken simultaneously from ISS and ground. Comparing the spatial structure of discrete aurora and the temporal variation of pulsating aurora, the accuracy of the data set is less than 0.3 s in time and less than 5 km in space in the direction perpendicular to the looking direction of the camera. The generated data set has a wide field of view ( 1,100 900 km), and their temporal resolution is less than 1 s. Not only that, the field of view can sweep a wide area ( 3,000 km in longitude) in a short time ( 10 min). Thus, this new imaging capability will enable us to capture the evolution of fine‐scale spatial structure of aurora in a wide area.

Compensation Method for Diurnal Variation in Three-Component Magnetic Survey

Considering that diurnal variation interferes with three-component magnetic surveys, which inevitably affects survey accuracy, exploring an interference compensation method of high-precision is particularly desirable. In this paper, a compensation method for diurnal variation is proposed, the procedure of which involves calibrating the magnetometer error and the misalignment error between magnetometer and non-magnetic theodolite. Meanwhile, the theodolite is used to adjust the attitude of the magnetometer to unify the observed diurnal variation into the geographic coordinate system. Thereafter, the feasibility and validity of the proposed method were verified by field experiments. The experimental results show that the average error of each component between the observed value of the proposed method and that of Changchun Geomagnetic station is less than 1.2 nT, which indicates that the proposed method achieves high observation accuracy. The proposed method can make up for the deficiency that traditional methods cannot meet the requirements of high accuracy diurnal variation compensation. With this method, it is possible for us to set up temporary diurnal variation observation station in areas with complex topography and harsh environment to assist aeromagnetic three-component survey.

Indoor Positioning Integrating PDR/Geomagnetic Positioning Based on the Genetic-Particle Filter

This paper proposes a fusion indoor positioning method that integrates the pedestrian dead-reckoning (PDR) and geomagnetic positioning by using the genetic-particle filter (GPF) algorithm. In the PDR module, the Mahony complementary filter (MCF) algorithm is adopted to estimate the heading angles. To improve geomagnetic positioning accuracy and geomagnetic fingerprint specificity, the geomagnetic multi-features positioning algorithm is devised and five geomagnetic features are extracted as the single-point fingerprint by transforming the magnetic field data into the geographic coordinate system (GCS). Then, an optimization mechanism is designed by using gene mutation and the method of reconstructing a particle set to ameliorate the particle degradation problem in the GPF algorithm, which is used for fusion positioning. Several experiments are conducted to evaluate the performance of the proposed methods. The experiment results show that the average positioning error of the proposed method is 1.72 m and the root mean square error (RMSE) is 1.89 m. The positioning precision and stability are improved compared with the PDR method, geomagnetic positioning, and the fusion-positioning method based on the classic particle filter (PF).

RFID aided SINS integrated navigation system for lane applications

To improve the lane vehicle position accuracy, RFID technology is applied to correct the position of the SINS irregularly with label positioning. The acceleration data of the vehicle in three directions is measured by the accelerometers of the inertial measurement unit, the attitude matrix is updated in real time using the angular velocity of the gyroscope output space, the acceleration component is transformed into the geographic coordinate system, and the acceleration of the inertial measurement unit. The data is subjected to an integral operation process to obtain a spatial displacement value of the vehicle. The real-time updating algorithm of the attitude matrix and the processing of the inertial measurement unit signal are presented. The quaternion-based algorithm is used to solve the attitude matrix as well as updating the coordinate system of the inertial navigation attitude matrix in real time. The Hilbert-Huang transform is used to filter the acceleration signal to solve the integrator saturation problem caused by the low-frequency component of the acceleration signal. The EMD algorithm based on the continuous root mean square error is applied in rejecting the low-frequency components in the signal. The simulation experiments show that the system can be reliable and high precision.

ПОСТРОЕНИЕ ЦИФРОВОЙ МОДЕЛИ РЕЛЬЕФА МЕТОДОМ РАДИОЛОКАЦИОННОЙ ИНТЕРФЕРОМЕТРИИ

The article discusses the experience of applying the technique of constructing a digital elevation model (DEM) by the method of radar interferometry using Sentinel-1A / 1B data on the territory of the Amur region near the city of Svobodny in June 2019. The presented method, which consists of 9 main stages, is implemented in the PHOTOMOD Radar software package. The stages of processing include: loading the initial data and converting them into the internal format of the program; creating a project for processing and combining images of an interferometric pair (recalculating the raster of the auxiliary image into the geometry of the main image); construction pictures of interferogram and coherence and it is also possible to calculate pictures of phase and amplitude; filtering the interferogram and phase transformation (recalculation of the obtained values in meters); construction of a digital elevation model and its geocoding into a geographic coordinate system (WGS 84). After that, the results obtained are assessed and compared with the SRTM digital elevation model, namely, a visual comparison of two digital elevation models, their subtraction (SRTM – model obtained from Sentinel-1A / 1B data) and a comparison heights characteristic relief points. Also made conclusions and considered the possibilities of further projects

ЙМОВІРНІ ЗМІНИ КЛІМАТИЧНИХ УМОВ УКРАЇНИ ДО СЕРЕДИНИ ХХІ СТ.

In Ukraine, as in the world, substantial climatic changes have happened throughout past decades. It is a fact that they are manifested in changing of parameters of the thermal regime, regimes of wind and humidity. It is expected that they will be observed also in future that will lead to aggravation of negative effects and risks due to climate change. That determines the relevance of the problem of forecasting such changes in future both globally and regionally. After all, knowledge of climate’s behavior in future is very important in the development of strategies, program and measures to adapt to climate change. The article is devoted to assessing spatio-temporal distribution main climatic indicators (air temperature, wind speed and relative humidity) in Ukraine, their variability and the probable values to the middle of the 21st century (2021-2050). Projection of changes in meteorological conditions was made for A1B scenario of SRES family using data of the regional climate model REMO and data from the hydrometeorological observation network of Ukraine (175 stations). Estimated data obtained from the European FP-6 ENSEMBLES project with a resolution of 25 km. For spatial distribution (mapping) we used open-source Geographic Information System QGIS, type of geographic coordinate system for project is WGS84. In the middle of the XXI century, if A1B scenario is released, it is expected a significant changes of climatic parameters regarding the 1981-2010 climatic norm: air temperature is rise by 1,5 °C, average wind speed is decrease by 5-8%, relative humidity in winter probably drop by 2%, but in summer it rises by 1,5%. The unidirectionality of the changes is characteristic only of air temperature, for wind speed and relative humidity the changes are in different directions. The intensity of changes is also not uniform across the country for all climatic parameters, has its regional and seasonal features. Statistical likelihood for most of highlighted changes for all climatic parameters is 66 % and more, the air temperature change is virtually certain (p-level &lt;0.001).

Spatial Coordinates Correction Based on Multi-Sensor Low-Altitude Remote Sensing Image Registration for Monitoring Forest Dynamics

Tree species diversity plays a significant role in our ecosystem. In order to monitor forest dynamics, hyperspectral remote sensing equipped on a small unmanned aerial vehicle (UAV) is commonly applied, such as individual tree detection and classification. However, low resolution, positioning errors and the imaging perspective of small UAV affected by wind speed/direction, complex terrain, battery capacity, aircraft posture, flying height and other human factors result in relatively large positional errors (i.e., GPS errors) in such hyperspectral images, and the precise forest dynamics monitoring is limited, especially in spatial analysis. In order to reduce the positional errors of hyperspectral images captured from a small UAV and provide a precise forest dynamics monitoring, we present a novel spatial coordinates correction approach by registering low-altitude UAV visible light and hyperspectral images. The proposed method first employs visible light images and ground control points to stitch a geographic coordinate system as our groundtruth. Hyperspectral images (UHI) are then registered onto the stitched visible light image (UVI) via a novel image registration method. Finally, spatial coordinates of the registered hyperspectral images are updated by using the aforementioned groundtruth. Extensive experiments on image registration and spatial coordinates correction demonstrate the favorable performance of our method. Compared against four state-of-the-art registration methods, our method shows the best registration performance, and the positional errors of hyperspectral images are significantly reduced. Such accuracy is considered very high in this research.

Distance metrics for data interpolation over large areas on Earth’s surface

Kriging models using five methods for calculating distance between locations on Earth’s surface are discussed. After reviewing statistical literature about kriging on a sphere, we discuss approaches for kriging on an ellipsoid, as well as a computationally intensive kernel convolution approach on an arbitrarily shaped three-dimensional body. Next, we propose computationally efficient kernel convolution algorithm. Then we explain how empirical Bayesian kriging interpolates data in a geographic coordinate system. The biggest computational and modeling advantage of EBK is that it divides data into subsets allowing for fast nonstationary data interpolation. We show by examples that empirical Bayesian kriging with chordal distances works well with both global and local data.

ANALISIS PERENCANAAN BUKIT BUATAN (ESCAPE HILL) TERHADAP TINGGI RUN UP UNTUK TEMPAT EVAKUASI SEMENTARA

As we know, there is still a lack of the optimal effort for temporary evacuation sites to face the various threats of the earthquake which may caused the tsunami in the city of Banda Aceh. To deal with this serious threat, it is necessary to prepare a place of salvation to face the tsunami. In this case, it is an escape hill. The objective of this research is to determine the bearing capacity of the subgrade to the escape hill planning and the amount of the settlement, due to the load of the embankment height (Hcrit) and the value of the slope safety factor (FK). This research is conducted in Desa Deah Baro with the GCS coordinates (Geographic Coordinate System) 5º33'45.72"N 95º17'51.34"E which was calculated by using the Plaxis 8.2 computing system on the variations of the embankment height which started from the existing which is 2,0 m height, 4,0 m, 6,0 m, 8,0 m, 10 m and 12 m (run-up performance). As the results of analysis, the researcher found that the addition of the load due to the increase in soil embankment height has resulted in an increase in the value of settlement to the soil stability with an average percentage of 2,86% and the safety factor decreasing value (FK) numbers on slopes with an average percentage of 0,10%. At 2,0 m embankment heights, the researcher obtained a settlement value of 0,271 cm with the safety factor value (FK) is 1,684 greater than 1. Furthermore, with the embankment height of 4,0 m, there is a settlement of 1,139 cm dan safety factor (FK) 1,365 greater than 1. At a embankment height of 6.0 m there is a settlement of 3,035 cm and a safety factor (FK) 1,214 greater than 1. At embankment heights of 8,0 m, the settlement is 6,244 cm with a safety factor (FK) 1,135 greater than 1. For embankment heights of 10 m and 12 m, the decrease occurred was 10,991 cm and 17,446 cm with safety factor (FK) = 1,095 and 1,044~1. The occured decline was still within the tolerance limits, so that the subgrade was still able to withstand the embankment. The results of the value of the safety factor (FK) showed that the slope was safe and did not indicate the slope slides.

Analysis of Focal Mechanism for Determine Fault Plane Orientation Using The Moment Tensor Inversion Case Study : West Java Geothermal Field

Micro earthquakes in geothermal field is used to monitor subsurface conditions especially in the reservoir. Micro earthquakes data can be used to determine focal mechanism or fault plane solution with moment tensor inversion method using ISOLA program in MATLAB-GUI. Focal mechanism or fault plane solution describes the orientation of the fault and slip on the fault relative to a geographical coordinate system. The arrival time of the P wave from the 3-component seismometer recording is used in moment tensor inversion and the frequency band that used is 0.02 to 0.08 Hz. The result of inversion with minor error indicated by the value of variance reduction approaching 1 calculated is from modelling waveform synthetic with green function and waveform observation. Fault plane solution in the field that represented by beach ball describes the dominant fault in the North is oblique fault with dip 30–90 degree and in the South is reverse fault with dip 20-85 degree.

Third dimension of a map

Abstract. A communication of information from its producer to a user can be done in many ways which differs in their effectivity. Although a map is a native communication channel for presenting of spatial data, a presentation of spatial data in 3D environment is a growing alternative in recent years. Therefore this chapter describes basic principles of dealing with third dimension in a map.Note that this contribution focuses on matters related purely to GIS. The contribution is not going to describe advanced 3D scene visualization techniques such as shadow modelling, ray-tracing, etc. (as they belong to computer graphics).Also a type of display in not addressed in detail. Just to mention in general, having a 3D scene, it can be displayed on:Monitor – then it is perspective visualization. A perception of depth emerges by moving the virtual observer position or line of sight.Monitor using passive or active glasses / 3D monitor – a full stereo perception emerges.3D print / hologram – physical/virtual three-dimensional scene emerges.Coming to GIS related issues. First of all, there exists solutions displaying 2.5 dimensional data and they are commonly called 3D GIS as well even if they do not support full 3D objects.Next, there are two different types of coordinate systems used: a Cartesian coordinate system, speaking geographically – a projected coordinate system, e.g. an UTM Zone. Then all coordinates are in the same units (usually meters). More challenging is the other type – a geographic coordinate system using latitude and longitude locating both objects and phenomena on Earth globe, but metric units for (ellipsoidal or orthometric) height – then different types of units (angular and metrical) are used for different axes. Such a situation is typical for virtual globes.Talking about cartography, there are two main approaches to visualize a 3D scene, photorealistic versus symbolized). Photorealistic approach tends to use real world textures and create an impression as close to real world as possible. The other approach, consisting of applying a cartographic symbols on the scene, challenges contemporary cartography, as not all cartographic techniques can be transferred from 2D to 3D. There can be distinguished among techniques able to apply without a change, techniques need to be adapted and inapplicable techniques.And last but not least major issue is that 3D GIS has to deal with large data in a different way than in 2D. Two dimensional GIS deals with large amount of data by a concept of scale dependent rendering (also called a scale dependent map) and using pyramiding and generalization techniques. But important thing is that always the whole thematic layer (or even a map) is represented at one level of detail in one view. When zoom in or out, an appropriate level of pyramid is depicted. A different approach is needed in 3D – instead of using one zoom level as a threshold for what and how to visualize, the observer position and line of sight have to be taken into account. Then, objects closer to observer have to be presented in more detailed way than objects away, no matter if they are from the same layer or different layers.

SAR platform positioning method based on improved Gauss–Newton–genetic hybrid algorithm

The traditional synthetic aperture radar (SAR) platform positioning methods based on the range-Doppler domain data, velocity and altitude information of the platform exist a large approximation error, which will not satisfy the requirement of accurate navigation. Additionally, the traditional positioning methods for solving non-linear equations are challenging due to the risk of falling into local optimal solution. In order to solve these problems, a new robust SAR platform positioning method based on the improved Gauss–Newton–genetic hybrid (GNGH) algorithm is proposed in this study. First, the position information of multi-feature points in geographic and imaging coordinate systems is acquired by adopting the image matching. Furthermore, the coordinate transformation is introduced to realise the uniform of feature point coordinates between the different coordinate systems. Finally, the accurate position of the platform is calculated through introducing GNGH algorithm to solve the non-linear equations constructed by the corresponding slant range information. So the trajectory deviation can be corrected effectively. Moreover, the proposed method can reduce the computation load and positioning error dramatically. The effectiveness of the proposed approach is confirmed and demonstrated via simulation and experimental results.

Wearable Anemometer With Multi-Sensing of Wind Absolute Orientation, Wind Speed, Attitude, and Heading

This paper presents a wearable anemometer for detecting wind absolute orientation and wind speed, as well as attitude and heading angles by incorporating a micro homemade thermal flow vector sensor with commercial triaxial micro accelerometer and triaxial micro magnetometer. The thermal flow vector sensor is comprised of three roundabout Pt hot-films uniformly distributed in a circle that is fabricated on a polyimide substrate. The flow sensor detects flow speed and flow relative angle in the body coordinate system, which is calculated from the heating powers of three hot-films that are operated in constant temperature difference circuits. The flow relative angle is further converted to the wind absolute orientation in the geographic coordinate system by means of the attitude and heading angle detected by using the triaxial accelerometer and triaxial magnetometer. The power consumption of the whole anemometer is about 400~500 mW under a wind blowing of 0 20 m/s. Using a rechargeable lithium battery with a capacity of 600 mAh, the anemometer can be continuously worked for about 4 h. Wind experimental results demonstrate that the root mean square (rms) error of the wind speed measurement reaches 0.17 m/s in the range of 0~18.9 m/s, the rms errors of wind relative angle and absolute orientation reach 2.79° and 3.22°, respectively, in the range of 0~360°. Attitude and heading experimental results illustrate that the rms errors of heading and roll measurements reach 0.42° and 0.15°, respectively, in the range of -180°~180°, and the rms error of pitch reaches 0.13° in the range of -90°~90°.