Browsing by Author "Desai, V."

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A study and implementation of mapping and speech recognition techniques for an autonomous mobile robot based on ROS
(Inderscience Enterprises Ltd., 2017) Srinivasa Rao, H.; Desai, V.; Bhat, R.; Jayaprakash, S.; Sampangi, Y.
Autonomous mobile robots work in close interaction with humans in environments such as homes, hospitals, public places and disaster areas. In autonomous mobile robots, the main constraints are safety, autonomy and efficiency in helping the humans. Given these constraints, developing the autonomous mobile robot technologies is a major challenge for both the industry and the research society. This paper work is about how an indoor autonomous mobile robot can work based on robot operating system and using Lidar and other sensors to create a map of an environment, and perform autonomous navigation with using capabilities like dynamic obstacle avoidance, speech recognition and video streaming. To achieve the above features, different algorithms like SLAM, AMCL, dynamic window approach algorithms, and CMU PocketSphinx speech recogniser are used. For video steaming, ROS web video server is used and the recorded video can be sent to a remote desktop system using ROS network. © 2017 Inderscience Enterprises Ltd.
An investigation on characteristics and free vibration analysis of laminated chopped glass fiber reinforced polyester resin composite
(Asian Research Publishing Network arpn@arpnjournals.com, 2016) Allien, V.; Kumar, H.; Desai, V.
In this paper material characterization and free vibration analysis of polyester resin based two, four and six layers chopped strand mat (CSM 450g/m2 specific weight) glass fiber reinforced with (CGRP) composite materials has been determined. In material characterization the tensile, flexural, impact, inter-laminar shear strength, fracture toughness has been evaluated. The results have revealed that, the four layer CGRP composite material has high impact, inter laminar shear strength and fracture toughness compared to two and six layers composite material. Free vibration analysis was carried out to determine the natural frequency of the CGRP composite materials theoretically and numerically (FEA). The result obtained from free vibration analysis indicated that natural frequency of six layers CGRP composite material is more than two and four layers CGRP composite material. © 2006-2016 Asian Research Publishing Network (ARPN).
An investigation on high temperature erosion behaviour of plasma sprayed CoCrALY/Al2O3/YSZ on fe and ni based alloys
(Universiti Putra Malaysia Press Tower 2, UPM-MDTC Technology Centre Serdang, Selangor 43400, 2017) Nithin, H.S.; Desai, V.; Ramesh, M.R.
Parts of aircraft and gas turbines used for power production are subjected to severe erosion damage since aircrafts frequently operate in sandy environment. Low cost fuel such as poor quality coal is used in gas turbines which produce suspended hard particle in the exhaust. In the past, researchers have worked on minimising the erosion by using certain coatings. Development of new coatings is necessary in order to explore further in improving resistance against erosion process under high operating temperature of gas turbine, aero engines and other components. In the present work, the investigation of elevated temperature erosion behaviour of CoCrAlY/Al2O3/YSZ coatings synthesised by plasma spraying on two different base metals, namely, Hastelloy X (Superni 76) and AISI 321 (MDN 321) was carried out. The coated samples were subjected to erosion test at 600ºC with the impact angles of 30º and 90º under steady state condition. Alumina powder was used as erodent material of uneven angular shape of 50 ?m particle size. The morphology and phase formed on eroded surface are characterised using SEM and X-ray diffraction to determine the erosion mechanism. The rate of erosion is determined by weight loss method and the CoCrAlY/Al2O3/YSZ coating showed up to about 25% lower erosion rate than the substrate alloy. It was observed that the erosion resistance of CoCrAlY/Al2O3/YSZ coating on both MDN 321 and Superni 76 gave almost similar erosion resistance which shows that the erosion behaviour of coating is not influenced by substrate unless spray parameter and substrate roughness is changed. © 2017 Universiti Putra Malaysia Press.
Analysing the combined effect of crystallographic orientation and grain refinement on mechanical properties and corrosion behaviour of ECAPed ZE41 Mg alloy
(National Engg. Reaserch Center for Magnesium Alloys, 2020) Sekar, S.; Narendranath, S.; Desai, V.
Two step equal channel angular pressing carried out on as cast ZE41 Mg alloy resulted in a remarkable grain refinement. As compared to grain size of 46 µm in as cast sample, refinement upto 2.5 µm was achieved after 8th pass equal channel angular pressing (ECAP). The combined effect of crystallographic orientation and grain refinement was investigated by analysing the mechanical properties and corrosion behaviour of ZE41 Mg alloy using electron back scattered diffraction (EBSD). The first stage comprises of 1st, 2nd, 3rd and 4th passes at a processing temperature of 300 °C while the 5th, 6th, 7th and 8th passes were ECAPed at 275 °C in second stage. The mechanical properties of ZE41 Mg 158 yield tensile strength (YTS), 230 ultimate tensile strength (UTS) and 7% elongation in as cast condition is enhanced to 236 YTS, 295 UTS and 19.76%, respectively, after first stage ECAP. The yield tensile strength deteriorated due to the effect of texture predominating grain refinement during the second stage ECAP. The corrosion resistance of ZE41 Mg was significantly enhanced by ECAP and is inferred from electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation results .The role of microstructure was minimal on corrosion behaviour of ZE41 Mg due to extra resistance when tested in 0 M NaCl. However, the influence of grain refinement greatly influenced the improvement in corrosion resistance of ZE41 Mg rather than crystallographic orientation observed from EBSD. In contrast, the crystallographic orientation predominated the effect of grain refinement during ZE41 Mg corrosion in chloride containing (0.1 M and 1 M NaCl) solutions. From the observation of results it is found that equal channel angular pressing has the dual advantage of improving mechanical properties and corrosion resistance of ZE41 Mg alloy. © 2020
Characterization of aircraft electro hydrostatic actuator using virtual instrumentation
(2015) Sp, K.; Desai, V.; Jeppu, Y.V.
In Aerospace industry, implementation of Automated Test System (ATS) at the assembly and manufacturing floor improves characterization accuracy and plays a vital role to substantiate the airworthiness of the aircraft components. It is very useful in realizing high quality standards of aircraft components by virtue of meeting predefined acceptance test criteria. This paper outlines comprehensive design and development of the noise and vibration monitoring system at assembly and manufacturing floor for characterization of Electro Hydrostatic Actuator (EHA) of aircraft using progressions in virtual instrumentation. In aircraft, the flight control actuation system are powered by centralized hydraulic pumps that are driven by the aircraft engine, while the back-up system are driven by electric or ram turbines. Distributed control of electric actuators with integration of control function in Flight Control Computer (FCC) and power electronics is a cost effective approach. EHA does also play a significant role in electrical actuation system, which use distributed electric power drive in driving a hydraulic transmission system. Hence, before integrating with the primary flight control actuation systems in aircraft, EHA's are required to be subjected to noise and vibration characterization, as part of assembly and manufacturing level testing. This method is intended at replacing the monotonous and time consuming traditional method of noise and vibration characterization of the electric actuators at assembly and manufacturing floor and to improve the reliability of the electric actuation components supplied to the aircraft manufacturers. The tests have been performed using a LabVIEW controlled virtual instrument measurement system that monitored the noise and vibration waveform with reference to the tacho signal. � 2014 IEEE.
Characterization of aircraft electro hydrostatic actuator using virtual instrumentation
(Institute of Electrical and Electronics Engineers Inc., 2015) Sp, K.; Desai, V.; Jeppu, Y.V.
In Aerospace industry, implementation of Automated Test System (ATS) at the assembly and manufacturing floor improves characterization accuracy and plays a vital role to substantiate the airworthiness of the aircraft components. It is very useful in realizing high quality standards of aircraft components by virtue of meeting predefined acceptance test criteria. This paper outlines comprehensive design and development of the noise and vibration monitoring system at assembly and manufacturing floor for characterization of Electro Hydrostatic Actuator (EHA) of aircraft using progressions in virtual instrumentation. In aircraft, the flight control actuation system are powered by centralized hydraulic pumps that are driven by the aircraft engine, while the back-up system are driven by electric or ram turbines. Distributed control of electric actuators with integration of control function in Flight Control Computer (FCC) and power electronics is a cost effective approach. EHA does also play a significant role in electrical actuation system, which use distributed electric power drive in driving a hydraulic transmission system. Hence, before integrating with the primary flight control actuation systems in aircraft, EHA's are required to be subjected to noise and vibration characterization, as part of assembly and manufacturing level testing. This method is intended at replacing the monotonous and time consuming traditional method of noise and vibration characterization of the electric actuators at assembly and manufacturing floor and to improve the reliability of the electric actuation components supplied to the aircraft manufacturers. The tests have been performed using a LabVIEW controlled virtual instrument measurement system that monitored the noise and vibration waveform with reference to the tacho signal. Â© 2014 IEEE.
Characterization of pneumatic muscle actuators and their implementation on an elbow exoskeleton with a novel hinge design
(Elsevier B.V., 2022) do Rosario Carvalho, A.D.D.R.; Karanth P, N.; Desai, V.
The exoskeleton plays an essential role in the field of physical rehabilitation. Several actuators are used for the exoskeleton application, but the pneumatic muscle actuator has proved to be the best due to its high power to weight ratio, compliance, and safe operation. The objective of this paper involves the fabrication and experimental characterization of a pneumatic muscle actuator to actuate an exoskeleton for the elbow joint. This paper presents the development and testing of twelve pneumatic muscles of varying materials and sizes, to find the best combination to suit the intended application. The characterization process involved several tests, which related force, deflection, and pressure at various loading conditions. A modular test rig was developed to conduct all the tests with minor adjustments to the test setup. The study also involved designing and developing an elbow exoskeleton to test the pneumatic muscle in the real-world scenario. The exoskeleton is designed with a novel hinge to compensate for the antagonistic nature of the pneumatic muscle actuator. The tests showed the muscles with higher tensile modules bladders having a lower hysteresis and better load handling capability, but these suffered from lower contraction and force characteristics. The styrene-based muscle with a 12mm bladder (S12LB) showed the best force and deflection characteristics at various pressures and loading conditions. The styrene bladder has a modulus closer to the skeletal muscle, therefore demonstrating higher compliance and making it a preferred choice for the exoskeleton application © 2022
Cutting Forces, Surface Roughness and Tool Wear Quality Assessment Using ANN and PSO Approach During Machining of MDN431 with TiN/AlN-Coated Cutting Tool
(Springer Verlag, 2019) V Badiger, P.V.; Desai, V.; Ramesh, M.R.; Prajwala, B.K.; Raveendra, K.
The aim of this study was to improve the life and performance of tungsten carbide turning tool inserts coated with TiN/AlN multilayer thin films using physical vapor deposition technique. Quality characteristics of the coating are evaluated using Calo and VDI 3198 tests. Thickness of the coating is found to be 3.651?m with adhesion quality of HF1. The performance of coated tool inserts is evaluated using cutting speed (59–118 m/min), feed rate (0.062–0.125 mm/rev) and depth of cut (0.2–0.4 mm) as process parameters in turning MDN431 steel. Experimental investigation has been carried out based on full factorial design, and regression analysis was used to analyze and build the mathematical models for cutting force and surface roughness. Multi-objective optimization of the process parameters has been done with the combination of desirability approach and MOPSO technique. Optimum machining condition for least cutting force and optimum surface roughness is found to be Vc=59m/min, f=0.063mm/rev and ap=0.2mm. Cutting force and surface roughness are reduced by 9% in TiN/AlN-coated tools compared with the uncoated tool. To improve the CoD and capability of predictive regression models, ANN modeling has been adopted. ANN trained model and mathematical regression models are used to predict the results and predict the responses, which follow the experimental data with minimum absolute error. The predicted results are validated using ANN and regression analysis found with minimum error, and developed models are adequate for further usage. Tool wear was reduced by 105% in TiN/AlN-coated tools compared with the uncoated tool. © 2019, King Fahd University of Petroleum & Minerals.
Design and characterization of a pneumatic muscle actuator with novel end-fittings for medical assistive applications
(Elsevier B.V., 2021) do Rosario Carvalho, A.D.; Karanth P, N.; Desai, V.
Pneumatic muscle actuators (PMA) are a class of soft actuators known for their high power to weight ratio and inherent compliance. The pneumatic muscle's inherent properties make them very favorable for assistive applications (e.g., medical exoskeletons). This study presents a novel end-fitting design that makes the developed pneumatic muscle actuator lightweight, cost-effective, and modular, thus simplifying the process of assembly and maintenance. The pneumatic muscle actuator assembled using the novel end fittings achieves a shorter overall length without compromising its contraction. The pneumatic muscle actuator has been assembled using a commercial bladder and a braided sleeve alongside a pair of 3D printed novel end-fittings. The paper also details the developed actuator's characterization for force and deflection parameters at various operating pressures. A total of four muscle actuators of varying diameters with constant actuation length (100 mm) were developed and tested to showcase the effect of size on the muscle actuator's behavior. The study presented here also involved comparing three mathematical models developed for pneumatic muscles in order to find a model which closely resembles the developed muscle actuator. Finally, the developed pneumatic muscle actuator's behavior is compared with a commercially available muscle to determine the efficacy of the developed muscle's design. The tests showed that the muscle using a bladder of smaller volume but higher tensile modulus had a higher accuracy and stable performance. As the muscle is intended for medical applications, it was also put through an endurance test with realistic loading and pressure conditions, which revealed very promising results. © 2021 Elsevier B.V.
Design and Fabrication of a Test Rig for Performance Analysis of a Pneumatic Muscle Actuator
(Springer Science and Business Media Deutschland GmbH, 2021) Yashas, M.; do Rosario Carvalho, A.D.; Karanth P, K.P.; Desai, V.
Artificial pneumatic muscle actuator (PMA) is used to convert pneumatic power to mechanical force. These actuators are like biological muscles, hence its name. PMAs have a wide range of applications ranging from robotics, industrial to the medical applications, as a result of its high power-to-weight ratio, nonhazardous, and compliant nature. The PMA, like any other actuator, has to be tested and validated before using it in any real-world application. An experimental procedure is set up to allow the designer to predict, analyze, and optimize PMA performance before its use in sensitive applications. To achieve this, a rigid experimental test rig needs to be designed to test properties of PMA such as displacement, force, and load capacity. Result of the experiment conducted on the standard PMA by using developed test rig has 5% variation with the values of the manufacturerâ€™s datasheet. Â© 2021, Springer Nature Singapore Pte Ltd.
Development and Characterization of Ti/TiC/TiN Coatings by Cathodic Arc Evaporation Technique
(Springer India sanjiv.goswami@springer.co.in, 2017) V Badiger, P.V.; Desai, V.; Ramesh, M.R.
Metallic nitride and metallic carbide coatings in general have good resistance to wear. In particular they are coated on the metal surfaces subjected to wear/abrasion under chemically aggressive environments. In the present work, Titanium based multilayered hard coatings are developed on the highly-alloyed steel MDN121 by cathodic arc evaporation technique. The microstructure and mechanical properties of titanium based multilayer coatings are investigated to analyze the latent of these protective coatings. Coating morphology and elemental composition, surface topography, crystal phase and presence of Diamond like carbon are investigated using techniques of field emission scanning electron microscopy equipped with EDS, scanning tunneling microscopy, glancing angle XRD, and Raman spectroscopy. The results indicate that the coatings developed are defect free, dense, homogeneous, and a coating thickness in the range of 1–2 µm is achieved. Hardness and elastic modulus of the coatings have been measured using nano indentation technique and are found to be 5.60 and 297.60 GPa respectively. The adhesions of the coatings have been measured using the nano scratch test and critical load is found to be at 47.70 mN. © 2017, The Indian Institute of Metals - IIM.
Development of an automated handwriting analysis system
(2011) Kamath, V.; Ramaswamy, N.; Navin, P.; Desai, V.; Kulkarni, S.M.
In the present study a method has been proposed for the behavioral prediction of a person through automated handwriting analysis. The present work identifies the psychological traits in the writing namely size, slant and pressure, baseline, number of breaks, margins, speed of writing and spacing between the words. The handwriting is analyzed through Image Processing in MATLAB. The behavioral pattern of the person is predicted from the above traits of the handwriting. The developed system identifies handwriting closely which may not be possible for a graphologist. It is real time and involves less image preprocessing. The proposed system is calibrated with manual analysis. The results obtained through the system are in good agreement to more than 80 percent of the cases with ideal manual analysis. © 2006-2011 Asian Research Publishing Network (ARPN).
Development of Guided Autonomous Navigation for Indoor Material Handling Applications
(Springer, 2018) Geetha Jayaprakash, A.; Bairampalli, S.; Desai, V.; Bhat, R.
In recent past emphasis on material handling requirements in industry has gone up considerably and in particular several researchers have attempted to improve the indoor material handling. In this paper an autonomous navigation system is implemented on a trolley for applications intending to move the trolley along a predefined path without human operator assistance. The trolley operates in two modes: Learning mode and Autonomous mode. In the learning mode the operator has to manually move the trolley along a path, it has to follow autonomously when the autonomous mode is activated. © Springer International Publishing AG 2018.
Dynamic analysis and optimization of SiC reinforced Al6082 and Al7075 MMCs
(Institute of Physics Publishing helen.craven@iop.org, 2019) Allien, V.J.; Kumar, H.; Desai, V.
Composites play a vital role in engineering applications. The main aim of this study was to analyse how addition of SiC will improve the damping properties of metal matrix composites (MMCs). The strengthening of composites depends on physical, mechanical and dynamic factors. In the present study, Al6082 and Al7075 aluminum alloy reinforced with (0, 1, 2, 3, 4, 5, 7.5, 10, 15 and 20) different weight percentages of silicon carbide particles (SiCp) MMCs have been fabricated through stir casting method. The microstructure, density, hardness, tensile strength, impact strength, natural frequencies and damping ratio of the MMCs were determined. The mechanical tests and free vibration analysis results revealed that the addition of SiCp reinforcement enhanced the strength and stiffness of the aluminum alloy MMCs. Multi-attribute decision making (MADM) techniques like analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS) methods were applied for determining the best fabricated MMCs. Based on MADM techniques, 15% SiC/Al7075 composite was selected as the best material and using response surface methodology (RSM) 13.66% SiC/Al7075 composite was found as the optimal composite material. © 2019 IOP Publishing Ltd.
Effect of combined grain refinement and modification on microstructure and mechanical properties of hypoeutectic, eutectic and hypereutectic Al-Si alloys
(Inderscience Publishers, 2015) Shivaprasad, C.G.; Kiran Aithal, K.; Narendranath, S.; Desai, V.; Mukunda, P.G.
The effect of melt treatment owing to the combined addition of grain refiner and modifier on the microstructure and mechanical properties of Al-Si alloys having 7% (hypoeutectic), 12% (eutectic) and 15% silicon (hypereutectic) is studied. 1 wt. % of Al-1Ti-3B Master alloy was used as grain refiner. For modification of eutectic Si, 0.2 wt. % of Al-10Sr Master alloy was added to hypoeutectic alloy and 0.4 wt. % is added to eutectic alloy as well as hypereutectic alloy. Furthermore, refinement of primary Si in hypereutectic alloy was achieved by addition of 0.04 wt. % of phosphorus. The goal of this investigation is to determine the influence of combined addition of grain refiner and modifier on mechanical properties and qualitatively correlate with the microstructural changes. © 2015 Inderscience Enterprises Ltd.
Effect of cutting parameters on tool wear, cutting force and surface roughness in machining of MDN431 alloy using Al and Fe coated tools
(Institute of Physics Publishing helen.craven@iop.org, 2019) V Badiger, P.V.; Desai, V.; Ramesh, M.R.; Prajwala, B.K.; Raveendra, K.
Thin solid films are used in cutting tools in order to improve its performance, reduce tool wear and improve tool life. Cathodic arc evaporation is the state of art PVD technique widely accepted in industries for the development of thin solid films. The turning cutting tool inserts are coated with AlCN/AlC and FeCrN monolayer thin solid films using cathodic arc evaporation technique. Quality characteristics of thin films are estimated using Calo and VDI3198 tests. Thickness of the coatings are found to be 1.430 and 1.475 ?m for AlCN/AlC and FeCrN coatings respectively and adhesion quality of HF1 is attained. Performance of the thin solid films are evaluated in machining MDN431 steel with range of cutting speed (59-118 m min-1), feed rate (0.062-0.125 mm/rev) and depth of cut (0.2-0.4 mm). Experiments are performed based on full factorial design and regression analysis. Optimization of the process parameters is carried out using combined techniques of desirability and Particle swarm optimisation (PSO). The objective of the study is to establish correlation between machining parameters with cutting force, tool wear and surface roughness. Optimal process parameter for least cutting force and surface roughness are obtained for coatings. ANN has been adopted to improve the coefficient of determination (CoD) and capability of predictive regression models. ANN trained model and mathematical regression models are adequate to predicted the responses, which follows the experimental data with minimum absolute error. The AlCN/AlC coatings exhibited lower cutting forces and surface roughness than FeCrN coated tools. Tool wear was reduced by 3.62 times in AlCN/AlC and 1.63 times in FeCrN coated tools compared to uncoated tool which is due to increased hardness and elastic modulus of the coating. © 2018 IOP Publishing Ltd.
Effect of L/D ratio on Al-Si functionally graded material cast through centrifuge technique
(2011) Aithal, K.; Narendranath; Desai, V.; Mukunda, P.G.
Functionally Graded Material (FGM) is a class of material wherein the properties and structure are varied intentionally from one side to the other side of the specimen. This paper describes the effect of L/D (Length to Diameter) ratio of the cast on cast Al-Si FGM. The present study uses Al-17%wt Si to cast FGM's. The cast is evaluated for Microstructure and Hardness all along the length of the specimen. Three L/D ratios: 0.5, 1.0, 1.5 were cast using the Centrifuge Technique. The microstructures showed that enrichment of primary Si was largest in 1.5 ratio compared to other two. Hardness value of the cast at the upper and lower region were examined and found that gradient of hardness was more in 1.5 case. High volume percentage of primary Si was nearly 26% in the upper region and a hypoeutectic structure in the lower region. � (2011) Trans Tech Publications.
Effect of L/D ratio on Al-Si functionally graded material cast through centrifuge technique
(2011) Kiran Aithal, A.S.; Narendranath; Desai, V.; Mukunda, P.G.
Functionally Graded Material (FGM) is a class of material wherein the properties and structure are varied intentionally from one side to the other side of the specimen. This paper describes the effect of L/D (Length to Diameter) ratio of the cast on cast Al-Si FGM. The present study uses Al-17%wt Si to cast FGM's. The cast is evaluated for Microstructure and Hardness all along the length of the specimen. Three L/D ratios: 0.5, 1.0, 1.5 were cast using the Centrifuge Technique. The microstructures showed that enrichment of primary Si was largest in 1.5 ratio compared to other two. Hardness value of the cast at the upper and lower region were examined and found that gradient of hardness was more in 1.5 case. High volume percentage of primary Si was nearly 26% in the upper region and a hypoeutectic structure in the lower region. Â© (2011) Trans Tech Publications.
Effect of process parameters on centrifugally cast Al-Si FGM
(2016) Kiran, A.S.; Desai, V.; Narendranath, S.; Mukunda, P.G.
Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation. � The Minerals, Metals & Materials Society 2016.
Effect of process parameters on centrifugally cast Al-Si FGM
(2013) Aithal, S, K.; Desai, V.; Narendranath, S.; Mukunda, P.G.
Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation.