Hard Iron Research Articles

Field test of high-power microwave-assisted mechanical excavation for deep hard iron ore

Microwave-assisted mechanical excavation has great application prospects in mines and tunnels, but there are few field experiments on microwave-assisted rock breaking. This paper takes the Sishanling iron mine as the research object and adopts the self-developed high-power microwave-induced fracturing test system for hard rock to conduct field experiments of microwave-induced fracturing of iron ore. The heating and reflection evolution characteristics of ore under different microwave parameters (antenna type, power, and working distance) were studied, and the optimal microwave parameters were obtained. Subsequently, the ore was irradiated with the optimal microwave parameters, and the cracking effect of the ore under the action of the high-power open microwave was analyzed. The results show that the reflection coefficient (standing wave ratio) can be rapidly (<5 s) and automatically adjusted below the preset threshold value (1.6) as microwave irradiation is performed. When using a right-angle horn antenna with a working distance of 5 cm, the effect of automatic reflection adjustment reaches the best among other antenna types and working distances. When the working distance is the same, the average temperature of the irradiation surface and the area of the high-temperature area under the action of the two antennas (right-angled and equal-angled horn antenna) are basically the same and decrease with the increase of working distance. The optimal microwave parameters are: a right-angle horn antenna with a working distance of 5 cm. Subsequently, in further experiments, the optimal parameters were used to irradiate for 20 s and 40 s at a microwave power of 60 kW, respectively. The surface damage extended 38 cm × 30 cm and 53 cm × 30 cm, respectively, and the damage extended to a depth of about 50 cm. The drilling speed was increased by 56.2% and 66.5%, respectively, compared to the case when microwaves were not used.

Dislocation hardening coupling between hard matrix and soft zones in a dual-phase heterostructured material

Strain hardening coupling between hard and soft zones is still not well understood in heterostructured materials. Here we report the coupling of dislocation hardening between hard iron matrix and soft copper zones in heterostructured Fe-40Cu dual-phase materials. Dislocation hardening is the predominant hardening mechanism in the Fe-40Cu materials, as dislocations dominate plastic deformation in both iron and copper. Low-temperature annealing kept highly deformed iron matrix strong and inductile but softened copper zones by promoting recrystallization in them. This raised plastic incompatibility and strain partitioning between iron matrix and copper zones during deformation. As a result, dislocations accumulated dramatically in copper zones but barely in the iron matrix. Copper zones produced high dislocation hardening to compensate for the low one of the iron matrix, raising the total strain hardening of the heterostructured Fe-40Cu materials. Lowering the plastic incompatibility between the iron matrix and copper zones weakened the strain partitioning between them and consequently depressed the dislocation hardening of copper zones. The role that copper zones played turned from producing high dislocation hardening to stabilizing the plastic deformation of heterostructured Fe-40Cu materials at the high strain level.

A Compensation Method in Magnetic Distortion Through Regularized Inverse Problems

In magnetic surveys, three-axis magnetometers (TAMs) are usually installed on large carriers, and the TAM outputs are inevitably subjected to errors from TAMs and the carrier (including scale factor, nonorthogonality, bias error, temperature error, soft iron error, and hard iron error). Traditional compensation methods may result in unreliable and unsuccessful solutions when maneuvers of the vehicle are constrained. Therefore, a compensation method based on regularized inverse problems is proposed. We inspect the performance of the proposed method by conducting simulated and semiphysical experiments. All the results indicate that the proposed calibration method can still achieve high performance in the case of narrow-range attitudes and obtain more accurate magnetic components.

Growth Kinetics, Microstructure Evolution, and Some Mechanical Properties of Boride Layers Produced on X165CrV12 Tool Steel

The powder-pack boriding technique with an open retort was used to form borided layers on X165CrV12 tool steel. The process was carried out at 1123, 1173, and 1223 K for 3, 6, and 9 h. As a result of boriding the high-chromium substrate, the produced layers consisted of three zones: an outer FeB layer, an inner Fe2B layer, and a transition zone, below which the substrate material was present. Depending on the applied parameters of boriding, the total thickness of the borided layers ranged from 12.45 to 78.76 µm. The increased temperature, as well as longer duration, was accompanied by an increase in the thickness of the FeB zone and the total layer thickness. The integral diffusion model was utilized to kinetically describe the time evolution of the thickness of the FeB and (FeB + Fe2B) layers grown on the surface of powder-pack borided X165CrV12 steel. The activation energy of boron for the FeB phase was lower than that for the Fe2B phase. This suggested that the FeB phase could be formed before the Fe2B phase appeared in the microstructure. The high chromium concentration in X165CrV12 steel led to the formation of chromium borides in the borided layer, which increased the hardness (21.88 ± 1.35 GPa for FeB zone, 17.45 ± 1.20 GPa for Fe2B zone) and Young's modulus (386.27 ± 27.04 GPa for FeB zone, 339.75 ± 17.44 GPa for Fe2B zone). The presence of the transition zone resulted from the accumulation of chromium and carbon atoms at the interface between the tips of Fe2B needles and the substrate material. The presence of hard iron and chromium borides provided significant improvement in the wear resistance of X165CrV12 steel. The powder-pack borided steel was characterized by a four times lower mass wear intensity factor and nine times lower ratio of mass loss to the length or wear path compared to the non-borided material.

Yaw/Heading optimization by Machine learning model based on MEMS magnetometer under harsh conditions

The paper's main goal is to accomplish a high accuracy of yaw/heading by Machine Learning approach when the motion range of vehicle/device calibration is limited. The nonlinear Random Forest (RF) Regression with proper training has a high potential to deal with the magnetometer uncertainty before calibration and during iron distortion cases. The proposed solution solely requires the magnetometer without other sensor's support. A Pan Tilt Unit-C46 (PTU-C46) with high precise positioning was used as a reference heading value to label the corresponding magnetic features in the learning model. The proposed approach helps yaw estimation to be carried out under harsh conditions, which resolve many difficulties in orientation tracking since the magnetometer is susceptible to hard iron and soft iron in the environment. In addition, many mechanical devices work only within the specific range and waste their dynamic motion around two axes or more just for calibration. Thus, the research focuses on the level rotation calibration around Z-axis within the restricted range of motion for practical application. The experiment was carried out using a low-cost platform equipped with Micro-Electro-Mechanical System (MEMS) sensors as gyroscope, accelerometer, and magnetometer. The 9 Degree of Freedom (DoF) Madgwick was implemented into the Microcontroller to compare with the proposed model. The sensor fusion can track the yaw value after the level calibration despite various error conduction. The RF model accomplishes a superior result with more stability and more minor error. Under iron disturbance or calibration absence, the ML model still maintains the good tracking command with maximum Mean Square Error of about 0.3°, while the Madgwick is unsuccessful in heading measurement due to huge error in these circumstances.

Soft and Hard Iron Compensation for the Compasses of an Operational Towed Hydrophone Array without Sensor Motion by a Helmholtz Coil.

Usually, towed hydrophone arrays are instrumented with a set of compasses. Data from these sensors are utilized while beamforming the acoustic signal for target bearing estimation. However, elements of the hydrophone array mounted in the neighborhood of a compass can affect the Earth’s magnetic field detection. The effects depend upon the materials and magnetic environment present in the vicinity of the platform hosting the compass. If the disturbances are constant in time, they can be compensated for by means of a magnetic calibration procedure. This process is commonly known as soft and hard iron compensation. In this paper, a solution is presented for carrying out the magnetic calibration of a COTS (Commercial Off the Shelf) digital compass without sensor motion. This approach is particularly suited in applications where a physical rotation of the platform that hosts the sensor is unfeasible. In our case, the platform consists in an assembled and operational towed hydrophone array. A standard calibration process relies on physical rotation of the platform and thus on the use of the geomagnetic field as a reference during the compensation. As a variation on this approach, we generate an artificial reference magnetic field to simulate the impractical physical rotation. We obtain this by using a tri-axial Helmholtz coil, which enables programmability of the reference magnetic field and assures the required field uniformity. In our work, the simulated geomagnetic field is characterized in terms of its uncertainty. The analysis indicates that our method and experimental set-up represent a suitably accurate approach for the soft and hard iron compensation of the compasses equipped in the hydrophone array under test.

Vehicle heading estimation of INS/magnetometer integrated system based on constant hard iron interference calibration

The integrated INS/magnetometer measurement is widely used in low-cost navigation systems. The integration has proven more effective in suppressing the divergence of heading than relying solely on a magnetometer because this is susceptible to local magnetic field interference, reducing heading accuracy. Magnetometers sense the local magnetic field that may be interfered by the nearby ferromagnetic material or strong electric currents. Hence, the magnetometer must be calibrated in the vehicle before use. When a magnetometer is installed near power components (engines, etc.), soft iron interference can be ignored. In the vehicle’s external environment, the time-varying hard iron interference can reach 100 times the strength of the geomagnetic field, meaning that a magnetometer cannot function efficiently because its accuracy is so reduced. Hence, the constant hard magnetic interference inside the vehicle is mainly concerned in this paper. An INS/Magnetometer heading estimation algorithm based on a two-stage Kalman filter is proposed to solve the problem by combining inertial sensor and magnetometer with attitude information. In the first stage filter, the constant hard iron interference is estimated by setting upward standing the three IMU axes. In the second stage filter, the INS/Magnetometer heading estimation is implemented. Finally, the results show that the algorithm improves the accuracy of vehicle heading calculations.

Three-Disperse Magnetorheological Fluids Based on Ferrofluids Induced Modification of Sedimentation by Addition of Nanoparticles

The effect of mixing suspended nanoparticles into a bi-disperse magneto-rheological fluid on sedimentation phenomena is explored. A reference bi-disperse MRF has been modified using a ferrofluid containing magnetite nanoparticles of two shapes (spheres or hexagonal platelets) suspended in paraffin-oil as carrier fluid. The reference MRF was prepared with a mixture of two diameter sizes for the micrometric particles. The reference MRF was also prepared using two different grades of carbonyl-iron micrometric particles (herein these will be referred to as HARD and SOFT), which differ each other for their mechanical properties. The experiment monitored the evolution with time of the sediment-supernatant interface. This experiment showed that the presence of nanoparticles (particularly the spherical ones) slows down the sedimentation effects in terms of ratio and rate, independently of the other characteristics of the fluid. This study also showed that fluids based on SOFT carbonyl iron powders, in presence of nanospheres, are more stable than HARD carbonyl iron powder based fluids, since their sedimentation rate slows down in the long term. At the same time, HARD particle-based magnetorheological fluids show smaller sedimentation ratios than SOFT based fluids.

An improved magnetometer calibration and compensation method based on Levenberg–Marquardt algorithm for multi-rotor unmanned aerial vehicle

In order to improvethe yaw angle accuracy of multi-rotor unmanned aerial vehicle and meet the requirement of autonomous flight, a new calibration and compensation method for magnetometer based on Levenberg–Marquardt algorithm is proposed in this paper. A novel mathematical calibration model with clear physical meaning is established. “Hard iron” error and “Soft iron” error of magnetometer which affect the yaw accuracy of unmanned aerial vehicle are compensated. Initially, Levenberg–Marquardt algorithm is applied to the process of sphere fitting for the original magnetometer data; the optimal estimation of sphere radius and initial “Hard iron” error are obtained. Then, the ellipsoid fitting is performed, and the optimal estimation of “Hard iron” error and “Soft iron” error are obtained. Finally, the calibration parameters are used to compensate for the magnetometer’s output during unmanned aerial vehicle flight. Traditional ellipsoid fitting based on least squares algorithm is taken as reference to prove the effectiveness of the proposed algorithm. Semi-physical simulation experiment proves that the proposed magnetometer calibration method significantly enhances the accuracy of magnetometer. Static test shows that the yaw angle error is reduced from 1.2° to 0.4° when using the proposed calibration model to calibrate magnetometers. In dynamic tests, the sensor MTi’s output is used as reference. The data fusion of magnetometer compensated by the proposed new calibration model based on Levenberg–Marquardt algorithm can accurately track the desired attitude angle. Experimental results indicate that the accuracy of magnetometer in the yaw angle estimation has been greatly enhanced. In the process of attitude estimated, the compensation magnetometer data given by this new method have faster convergence speed, higher accuracy, and better performance than the compensation magnetometer data given by traditional ellipsoid fitting based on least squares algorithm.

Structure and Topography Modifications of Treated AISI 316LN Stainless Steel Surfaces after Friction in Dry Sliding Contact by Case Hardening Process

Austenitic stainless is having corrosion resistance property, but certain mechanical applications require improved resistance to wear, inferior cavitation, susceptibility to sensitization. These steels have numerous favourable circumstances for great cryogenic - properties, anti-corrosion, and bio-compatibility. So these steels have a broad application in low temperature innovation, saltwater applications, nourishment industry, bio-medicine, petro-chemical handling, and so forth when alloyed with nitrogen, austenitic treated steels has a progressively steady austenite structure, better mechanical properties and better wear opposition, which has animated extraordinary enthusiasm for this exploration work. Many surface hardening techniques are available, the best surface modification technique is chosen for improved service performance. Surface engineering is a technique to alter the surface of a material by mechanical or microchemical method without affecting the material properties. The alterations are done on the surfaces subjected to the liquid nitriding process to produce a hardened surface. Chosen for this research workbased on their wide application, the wear behaviour of AISI 316LN stainless steels was investigated. Of the various surface hardening techniques available, nitriding is chosen, so that these nitrogen gets penetrated into the material, in which hard iron chromium nitrides are formed at the surface level. AISI 316LN specimens were subjected to salt bath nitriding process. The specimens were nitrided to 60 minutes, 120 minutes and 180 minutes respectively. The specimens were undergone with wear tests by standardized tribiological wear machine and finally the metallographic studies were made.

A Stochastic Optimization Approach to Magnetometer Calibration With Gradient Estimates Using Simultaneous Perturbations

Triaxial magnetometers are indispensable part of every attitude sensing equipment for providing heading information. However, magnetometer measurements are affected by a number of error sources such as soft iron, hard iron, sensor nonorthogonality, and bias. These erroneous measurements, if not properly calibrated, deteriorate the quality of attitude estimates. In this paper, we present a new approach to calibrate triaxial magnetometer measurements by posing the calibration problem as a stochastic optimization problem. A scalar objective function is derived which involves magnetometer calibration parameters corresponding to all distortions. In order to recursively solve for optimized calibration parameters, a modified version of simultaneous perturbation stochastic approximation for the gradient is proposed for faster convergence. The proposed approach places no restrictions on the number of parameters involved and offers a complete solution by solving for all calibration parameters. The proposed approach is tested and validated using experimental data and the performance is compared against a reference approach.

Real-time calibration algorithm of magnetometer for spinning projectiles

Purpose In spite of the vehicle, magnetic field interference can be reduced by some measures and techniques in ammunition design and manufacturing stage, the corruption of the vehicle magnetic field can still reach hundreds to thousands of nanoteslas. Besides, the magnetic field that the ferromagnetic materials generate in response to the strong magnetic field in the vicinity of the body. So, a real-time and accurate vehicle magnetic field calibration method is needed to improve the real-time measurement accuracy of the geomagnetic field for spinning projectiles. Design/methodology/approach Unlike the past two-step calibration method, the algorithm uses a linear model to calibrate the magnetic measurement error in real-time. In the method, the elliptical model of magnetometer measurement is established to convert the coefficients of hard and soft iron errors into the parameters of the elliptic equation. Then, the parameters are estimated by recursive least square estimator in real-time. Finally, the initial conditions for the estimator are established using prior knowledge method or static calibration method. Findings Studies show the proposed algorithm has remarkable estimation accuracy and robustness and it realizes calibration the magnetic measurement error in real-time. A turntable experiments indicate that the post-calibration residuals approximate the measurement noise of the magnetometer and the roll accuracy is better than 1°. The algorithm is restricted to biaxial magnetometers’ calibration in real-time as expressed in this paper. It, however, should be possible to broaden this method’s applicability to triaxial magnetometers' calibration in real-time. Originality/value Unlike the past two-step calibration method, the algorithm uses a linear model to calibrate the magnetic measurement error in real-time and the calculation is small. Besides, it does not take up storage space. The proposed algorithm has remarkable estimation accuracy and robustness and it realizes calibration the magnetic measurement error in real time. The algorithm is restricted to biaxial magnetometers’ calibration in real-time as expressed in this paper. It, however, should be possible to broaden this method’s applicability to triaxial magnetometers’ calibration in real-time.

Robust ellipsoid fitting method based on optimization of a novel nonlinear cost function in navigation systems

Low-cost sensors based on micro-electro-mechanical systems (MEMS) are typically used for attitude determination in navigation systems especially magnetometer which is used for heading determination. The measured value of the MEMS magnetometer is subjected to different kinds of error such as random noise, constant bias, non-orthogonality, scale factor deviation and more importantly hard iron and soft iron effects. Therefore, in order to reach more accurate measurement, high-precision calibration is needed. One of the most common methods for calibrating MEMS magnetic sensors is least squares ellipsoid fitting. But, the common least squares ellipsoid fitting method can be inefficient for real-time applications in the presence of colored noise and outliers. In this paper, a modified ellipsoid fitting method is proposed in which a nonlinear optimization is developed to minimize a novel cost function. In the cost function of the proposed robust method, the effect of outliers and noise is considered and the standard deviation of the data is kept minimum. Finally, the efficiency of the new algorithms is demonstrated through the experimental results.

Geology of the Gouap iron deposit, Congo craton, southern Cameroon: Implications for iron ore exploration

The Ntem Complex represents the northwestern edge of the Archean Congo craton in southern Cameroon where numerous banded iron formation (BIF)-hosted iron deposits have been discovered. The Gouap iron deposit, which is located on the western edge of the Ntem Complex, is one of the recent discoveries of iron deposits in this area. In this study, geological mapping, detailed drillcore logging and petrographical studies reveal that the Gouap iron deposit comprises of two lithostratigraphic units, namely the BIF and the Country rocks. The BIF unit consists of amphibole BIF and amphibole-pyrite BIF, whereas the Country rocks unit is made up of gneisses (garnet, amphibole–magnetite and amphibole–garnet–pyrite gneiss), schists (amphibole–magnetite and garnet–magnetite micaschist), quartzites and dolerite sills.The BIFs are well interlayered and observed to be in sharp or gradational contacts to their associated country rocks. The mineral assemblages of the BIFs and wallrocks (except the dolerites) indicate that both units have been metamorphosed under amphibole facies conditions. Two main iron mineralization types are identified in the Gouap deposit: the soft iron type which is mainly located in the western and northern parts and the hard iron type mostly confined to the southern sector of the deposit.The structural controls of the Gouap iron deposit are better observed in drillcore samples other than on the outcrop-scale. There are three principal deformation events (D1, D2 and D3) that led to the development of foliation, folding and faulting respectively. The iron mineralization are mostly concentrated on the F2 fold hinge zones and fractures that acted as passage ways for the circulation of meteoric water at surface. We suggest that the following three major processes that led to the formation of the Gouap deposit: (i) the chemical precipitation of chert and iron-oxide followed by sedimentation and diagenesis that formed chert–magnetite BIFs; (ii) secondly, the amphibolite facies metamorphism and deformation that formed quartz–magnetite BIFs, which constitute the main iron ridge located on thicker zones of fold noses; and (iii) finally, the Gouap BIFs have been upgraded to medium-grade iron ore due to supergene enrichment processes, which are restricted to the modern land surface and locally reached deeper levels through fault and fracture zones. The western and northern parts of the Gouap deposit have been identified as potential exploration target areas for iron mineralization. Even though the iron formation processes of the Gouap deposit are not yet completely understood and many questions remain unanswered regarding the genesis of the soft and hard iron mineralization, these new insights have important implications on the exploration drilling strategies of this deposit.

Calibration of triaxial magnetometer with ellipsoid fitting method

The accuracy of the triaxial strapdown magnetometer is limited by the scaling factor, three-axis orthogonality, offset errors, hard iron and soft iron effects of the platform, a calibration method of the triaxial strapdown magnetometer is proposed in this paper. Firstly, the integrated error model of the triaxial magnetometer is established without simplification, then the error calibration parameters are calculated by the ellipsoid fitting method, and the output of triaxial strapdown magnetometer can be calibrated by the calibration parameters. At last, simulation experiments are built for verification of the proposed calibration method. The simulation results show that the proposed method can reduce 94.6% of magnetometer errors and magnetic inference. The proposed calibration method can effectively calibrate the triaxial strapdown magnetometer.

SOIL CONTAMINATION INDUCED BY HISTORICAL ZINC-LEAD ORE MINING AND IRON AND ZINC SMELTING IN THE CENTRAL PART OF THE UPPER SILESIAN INDUSTRIAL REGION (SOUTHERN POLAND)

The purpose of the work was to determine the degree of accumulation of heavy metals, arsenic and sulphur in the soils of the central part of the Upper Silesian Industrial Region. Heavy industry, mining of metal ores and hard coal, iron and non-ferrous metallurgy as well as the discharge of industrial and municipal sewage caused a strong degradation of the natural environment of this area. The content of twenty one elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, P, Pb, S, Sr, Ti, V i Zn) have been assayed in the soils of central part Upper Silesian Industrial Region. The contamination of the soils was assessed on the basis of contamination factors, enrichment factors and geoaccumulation indexes. The tests revealed elevated content of metals, arsenic and sulphur exceeding the levels of the regional geochemical background. Factor analysis made it possible to combine chemical elements into groups, probably derived from the same lithological or/and anthropogenic sources.

Magnetometer Bias Finite-Time Estimation Using Gyroscope Data

This paper deals with the problem of estimating the hard iron bias affecting the measurements provided by a triaxial magnetometer. The estimation is carried out using measurements from a magnetometer and a gyroscope mounted on the same inertial measurement unit. The described solutions ensure finite-time estimation performance and robustness against measurements noise. The effectiveness of the proposed solutions is proved by experimental tests carried out using real inertial sensors.

Development of efficient formulation for the removal of iron sulphide scale in sour production wells

AbstractIron sulphide scale, which exists in different forms, is common in sour oil and gas production wells. Iron sulphide hard scales are difficult to remove with acids, requiring mechanical intervention or the replacement of the production tubing. An environmentally friendly formulation with a high pH is proposed for the removal of both soft and hard iron sulphide scale from oil and gas wells. The formulation consists of DTPA (di‐ethylene tri‐amine penta acetic acid) in addition to K2CO3 as a catalyst. High pressure high temperature solubility experiments were performed under both static and dynamic conditions in the temperature range of 70–150 °C and a constant pressure of 3447.38 kPa. Several combinations of the catalyst and DTPA chelating agent were used to optimize the catalyst/DTPA ratio to achieve maximum scale solubility. Field scale samples were collected and analyzed using XRD. The scale removal efficiency of the proposed formulation outperforms that of the current formulations used in the oil industry, with the added advantage of not releasing H2S. The optimum DTPA concentration is 20 wt% and the optimum catalyst concentration is 9 wt%, which provides a solubility of 90 % of the field scale. In addition, the ecotox profile of the proposed formulation is better than that of the currently used formulations because toxic corrosion inhibitors are not used. The maximum reported corrosion rate for the new formulation is 0.036 kg/m2, which is well below the acceptable limit (&lt; 0.227 kg/m2).

Investigation of usability of limonite aggregate in heavy-weight concrete production

Limonite (Fe2O3·xH2O) is a soft or brown, hard iron mineral, usually in yellow colour. It is also used as a pigment since it contains iron ore. It is believed that it can also be used in the production of heavy concrete due to its 60% iron ore content. In this paper, an experimental study was carried out on radiation shielding properties and certain physical and mechanical properties of normal and limonite reinforced concrete. For this purpose, with the normal concretes prepared according to standards, amounts of aggregates were reduced at the rates of 20%, 40%, 60%, 80% and 100% by volume respectively, and heavy concrete mixes were prepared that were obtained by adding limonite at the same rates in their place. With limonite reinforcement, compressive and flexural strength of the concrete produced decreased, water absorption amount increased and their radiation permeability significantly decreased.

Navigational Challenges in Diver-AUV interaction for underwater mapping and intervention missions

Diver Navigation and Imaging System (DiNIS) is a compact, capable, integrated, underwater hand-held diver navigation system. DiNIS provides a complete suite of commercial underwater navigation sensors for the purpose of waypoint navigation, Intelligence, Surveillance, and Reconnaissance (ISR), bathymetry, and underwater imagery in the form of both sonar and video. DiNIS functionality includes Mission Planning, Waypoint Navigation, Sonar Imagery, Video Imagery, and Marking of Targets of Interest. During the recent sea trials DiNIS achieved excellent performance and navigation capability was superb. The average error was 0.3° - 0.5° of distance traveled after accounting for any offsets or errors in our position marks (GPS error). Moreover, we desigend an on-board calibration routine that helps with compensating for hard iron signature of the device, which can be performed in air or in-water. Our Diver Navigators equipped with these components can then work cooperatively with Autonomous Underwater Vehicles (AUV), autonomous surface vehicles (ASV) or manned surface/subsurface vessels equipped with much higher grade navigation sensors.