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Transfer Alignment Technique for Shipboard Missile Strapdown Inertial Navigation System using an Adaptive Kalman Filter
Get PDFMissile Guidance system needs accurate estimates from Inertial Navigation System (INS) for guiding
the vehicle towards the target. In this paper a target point, specified before launch, in a battlefield scenario
is considered for a landmark using missile Strap Down Inertial Navigation System (SDINS) aided by Master
INS (MINS) placed on a moving platform. Azimuth information of the missile is one of the most critical
navigation states for estimation on the moving platform before launching the missile for precise impact.
An Adaptive Kalman Filter (AKF) based on the error state model is formulated. The 7-state AKF with 4-measurement forms the core, where the filter gain of the innovation sequence (measurements) is
evaluated. This approach of adaptively computing the gain is tested in a laboratory, on a van and in a ship
trial, culminating in a successful guided missile launch. Mean and the covariance of the measurement
residuals were used in a unique way to compute adaptive gain after the accumulation of initial samples.
A Master INS (with advanced Gyros) whose accuracy is much higher than the accuracy of the missile’s
SDINS is used for velocity matching algorithm before the launch with execution of an S-maneuver for generation
of accelerations towards observing the states more appropriately. Estimated error states were used in a feedback mode to get near the true orientation of the Missile’s slave INS. Error quaternions are used for this purpose in the feedback and the gains were selected using offline matrix Riccati equation solution in a discrete domain as used in the modern control system. The results were very encouraging with less than 5 arc minutes of error in azimuth
Ballistic Studies of the Rotational Motion of the Artillery Projectile into Account the Equatorial Damping Moment
Get PDFThe problem of calculating the equatorial damping moment during trajectory flight is an actual problem inballistic studies of the rotational motion of artillery projectiles. The practice of ballistic research needs short algorithmsthat make it possible to calculate the damping moment together with the calculations of the trajectory parametersunder conditions of continuously changing characteristics of the oncoming flow. In this regard, a simplified methodfor calculating the equatorial damping moment of artillery projectiles in the oncoming flow is proposed, based onthe differentiation of the dependence for the overturning aerodynamic moment by the angle of attack and the Machnumber of the oncoming flow. Calculations of the parameters of the rotational motion of the 155-mm artilleryprojectile on the flight trajectory have been carried out. The influence of the equatorial damping moment on theperiodic components of the angular displacements of the projectile is revealed. The results of ballistic calculationswith the loss of stability of the rotational motion of the projectile showed the destabilizing effect of the equatorialdamping moment on the boundary parameters in terms of stability in the case of opposite directions of rotation ofthe projectile and crosswind
Tool Wear and its Effect on Residual Tensile Strength in Drilling of Quartz Cyanate Ester Polymeric Composite
Get PDFQuartz-Fibre-Reinforced cyanate ester Plastics (QFRP) has superior performance in terms of mechanical, electromagnetic properties and are being widely used in military applications. Drilling is the general machining process for making hole to join the composite part to another sub-assembly. This study presents an influence of optimized drilling parameters on carbide tool wear and its impact on hole characteristics in QFRP composite. The aim is to achieve the optimum use of drill during the drilling process from application perspective without compromising the quality. In addition, the effect of tool wear and its impact on residual tensile strength of quartz composite are studied. The dominant wear mechanism observed is flank wear caused by the abrasive nature of the quartz fibre. The tool wear and delamination factor after drilling 200 holes are 186 µm and 1.40 respectively. The residual strength is affected by the tool wear due to relatively poor interlaminar property between fiber and resin in this quartz composite. The residual strength of quartz specimen drilled with the tool after drilling 200 holes is 14 % lower than the property of specimen drilled with fresh drill. The highlight of the present work is a combined analysis of wear in the tool, delamination induced and residual strength of quartz specimen. The results of this study strengthen the understanding of the drilling process of quartz polymeric composite material in aerospace applications
Experimental Investigation of Peak Temperature and Microhardness in Friction Stir Processing of AA6082 T6 using Taguchi GRA
Get PDFFriction stir processing demonstrated tremendous potential for improving mechanical properties and its success relies on the optimal level of process parameters that result in a flawless stir zone. The present study is an experimental investigation of performance characteristics peak temperature and microhardness on FSPed AA6082-T6. The experiments are designed using the Taguchi L16 orthogonal array by considering four different levels of rotational speed, traverse speed, shoulder diameter, and tilt angle. The grey relational analysis is used for multiple responses to optimise the FSP process parameters and analysis of variance is utilised to establish the relevance of parameters for these responses. According to the findings, the shoulder diameter and traverse speed are the most important determinants for peak temperature and microhardness. It is observed from the experimental analysis that the main reasons for defect formation are either excessive or inadequate heat generation. The multi-response optimal condition is attained at a rotating speed of 1400 rpm, transverse speed of 112 mm/min, shoulder diameter of 25 mm, and tilt angle of 1º
Evolutionary Trends in True Time Delay Line Technologies for Timed Array Radars
Get PDFTimed array technology is rapidly evolving in multiple areas such as high resolution imaging radar, automotive, medical, high data rate communication applications etc. Timed arrays by utilising True Time Delay (TTD) lines in place of phase shifters mitigate beam squint and pulse dispersion issues associated with wide instantaneous bandwidth arrays. This paper presents on review of evolutionary trends in TTD line architectures starting from coaxial cable to photonic integrated circuit. The paper also reports on critical parameters of TTD lines, their importance and implication in design of typical X-band imaging radar. Comparison of different TTD line architectures in terms of configuration, implementation, merits and demerits are discussed in detail for wideband array application. The paper also brings out the integration aspects of TTD lines as part of T/R modules and proposes suitable design schemes towards performance optimization and realisation of timed arrays
Molecularly Imprinted Polymer Based Potentiometric Sensor for the Selective and Sensitive Detection of Nerve Agent Simulant Parathion
Get PDFIn this study, a potentiometric sensor was developed for the analysis of the parahtion which is a nerve agent simulant and pesticide. A molecularly imprinted polymer was used as the recognition layer in the electrode used in the potentiometric sensor. Parathion is also used as both an organophosphorus pesticide and a nerve agent simulant. For this reason, analysis methods to be developed for parathion are very important. The most important advantages brought by MIP-based sensor systems are; fast analysis, sensitive analysis, and the ability to analyze at very low concentrations. The sensor developed in our study was validated for parathion adsorption. In our study, first, Parathion imprinted polymers were synthesized. The synthesized MIPs are used as the recognition layer in the potentiometric sensor. The characterization of parathion imprinted polymers was done by FESEM, FT-IR, and zeta-sizer measurements. Optimization of the working conditions was carried out for the developed sensor system. The working pH was found to be 7.4.Measurements were taken for parathion samples with different concentrations under optimum operating conditions. When the results obtained were examined, a large linear range (10-8-10-4 mol L-1) and a satisfying detection limit against parathion (1.86 × 10-8 mol L-1) were calculated. Interference effect analysis was carried out within the scope of the performance tests of the potentiometric sensor. The analysis showed that interference did not affect the experimental results. In order to examine the matrix effect of the real sample environment, analyses were carried out in tap water and lake water. The recovery values in the analysis results are quite good. The results of the experiments show that the sensor we have developed can be used successfully in complex matrix environments
Novel Attitude Estimation Of Strapdown Inertial Navigation Systems With Singular Value Decomposition Technique
Get PDFDavenport’s q method & the Singular Value Decomposition (SVD) method are the two vigorous estimators that reduces Wahba’s loss function. In these, the q method is slightly quicker due to its computation of optimum quaternion as an eigenvector of a symmetric 4x4 matrix through the prevalent eigenvalue. The ESOQ and ESOQ2 (EStimators of the Optimal Quaternion) and the QUEST (QUaternion ESTimator) algorithms are less determined as the extreme eigenvalue’s distinguishing polynomial equation is solved by them. These estimators are apt to track the undulations of the sea with equivalent precision and accurateness. The SVD method is chosen and shown to be the most robust of all the hostile methods for the orientation of SDINS (Strap-Down Inertial Navigation Systems) using rate matching observations at sea in this paper. SVD is known most robust decomposition of all the decompositions of a matrix. SVD based attitude estimation being a batch technique would suffer from much less computational issues
Experimental Investigation of the Muzzle Blast for the Amphibious Rifles when Shooting Underwater
Get PDFDesigned for amphibious combat forces, the amphibious rifle is a revolutionary new kind of weapon. This firearm's design and the determination of the effect of shooting on the shooter are both dependent on the development of the underwater muzzle blast. In this work, an experiment to evaluate the muzzle blast overpressure and gas bubble characteristics of an amphibious rifle when shooting underwater is performed in order to better understand the weapon's capabilities. This inquiry is focused on the 5.56 mm amphibious rifle with 5.56x45 mm underwater ammunition. The results of the experiments indicated that the Rayleigh-Plesset equation may be used to describe and predict the size of gas bubbles. The experimental data may be utilized to compute the law of change of overpressure based on the experimental results. Also, it is a very important base for studying, designing, making, and mastering weapon technology, which are all very important steps in the development of weapon technolog
Development of an In house Computer Code for the Simulation of Detonation Shock Dynamics in Underwater Explosion Scenario
Get PDFDetonation Shock Dynamics (DSD), involved in an underwater explosion scenario is numerically simulated by an in-house computer code, ‘DSSDYN’. The simulation is based on Chapman-Jouguet (CJ) theory, formulated in Arbitrary Lagrangian Eulerian frame work. Specifically, the propagation of detonation front is simulated with‘Burn Fraction Model’. The classical burn fraction model is improved for achieving better computational efficiency. The simulation capability of DSS-DYN is demonstrated through a case study on explosion of PETN charge under the deep-water medium.Through this study, the salient features of DSD with better insight have been brought out. Besides, the physical parameters, such as work potential of PETN, are predicted efficiently.The apportionment of energy distributions indicates that about 70 % of chemical energy of explosive is transmitted to the surrounding water that is the major contribution of damage potential of the explosive. The predictions of peak velocity and peak pressure values by DSS-DYN and LS-DYNA show satisfactory comparison.DSS-DYN consumes lesser computational time (~1h), compared to LS-DYNA (~3h)
The Algorithm and Computer Code for Predicting Detonation Wave Parameters of Aluminized Explosives
No full textIn this work, the algorithm and computer code, named DETO, used to calculate the detonation wave parameters (i.e., the velocity of detonation and the detonation pressure) of aluminized explosives, based on the chemical equilibrium theory of detonation products, the hydrodynamic theory of detonation process, and the Becker - Kistiakowsky - Wilson (BKW) equation of state. The aluminum (Al) content reacting with detonation products on the detonation wavefront can be changed according to the user's assumptions. Compared to experimental data for several aluminized explosive types, the results calculated by DETO have the same, even higher accuracy than those calculated by other computer codes previously published. Specifically, the mean absolute deviation from experimental data is about 2% for the velocity of detonation (VOD) and about 8% for the pressure on the detonation wavefront. In addition, the study also confirmed that about 50% of Al powders participate in the reaction on the detonation wavefront