Department of Mechanical Engineering

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IIT Jodhpur

World University root node

Use of Kinect Sensor for Building an Interactive Device

End milling of the curved surfaces is characterized by significant amount of engagement variation along the tool path which results in deflection-induced surface error on the machined components. Feed rate regulation cannot be used in this case to minimize the surface errors as it necessitates continuous change in feed rate along the tool path which deteriorates surface finish and lowers productivity. Another approach in the form of tool path modification scheme was also proposed in the literature to minimize engagement variation at corners of a pocket. This approach has been effective in reducing fluctuations of engagement at corners and cannot be applied directly in machining of curved geometries where engagement variation is continuous along the entire tool path. Keeping these limitations in focus, a new methodology is proposed in this article to minimize surface error variation that modifies machining strategy for the curved components. The strategy proposes machining of the curved components into two different stages: first, generating the modified semi-finishing geometry using algorithm proposed in this article and then producing the desired geometry using conventional contour parallel tool path. The methodology generates the modified semi-finishing geometry such that the engagement offered is constant when a finishing pass is made. The effectiveness of the proposed methodology has been verified by performing computational studies and machining experiments on typical curved geometries. It is observed that the proposed methodology is quite effective in minimizing the variation in the surface error on the machined components. © IMechE 2015.

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

Machining of curved geometries with constant engagement tool paths

The thin-film structures of DC/FR magnetron-sputtered ZrOx/ZrC–ZrN/Zr tandem solar-selective coatings are investigated using X-ray diffraction and room-temperature Raman spectroscopic measurements. These studies suggest that the major contribution is coming from h-ZrN0.28, c-ZrC, h-Zr3C2 crystallographic phases in ZrN–ZrC absorber layer, in conjunction with mixed ZrOx crystallographic phases. The change in structure for thermally annealed samples has been examined and observed that cubic and hexagonal ZrOx phase converted partially into tetragonal and monoclinic ZrOx phases, whereas hexagonal and cubic ZrN phases, from absorber layer, have not been observed for these thermally treated samples in air. These studies suggest that thermal treatment may lead to the loss of ZrN phase in absorber, degrading the thermal response for the desired wavelength range in open ambient conditions in contrast to vacuum conditions. © 2016, Springer-Verlag Berlin Heidelberg.

Department of Mathematics

Department of Physics

Applied Physics A: Materials Science and Processing

Investigation of ZrOx/ZrC–ZrN/Zr thin-film structural evolution and their degradation using X-ray diffraction and Raman spectrometry

This is the first of a series of papers devoted to the study of h-p spectral element methods for solving three dimensional elliptic boundary value problems on non-smooth domains using parallel computers. In three dimensions there are three different types of singularities namely; the vertex, the edge and the vertex-edge singularities. In addition, the solution is anisotropic in the neighbourhoods of the edges and vertex-edges. To overcome the singularities which arise in the neighbourhoods of vertices, vertex-edges and edges, we use local systems of coordinates. These local coordinates are modified versions of spherical and cylindrical coordinate systems in their respective neighbourhoods. Away from these neighbourhoods standard Cartesian coordinates are used. In each of these neighbourhoods we use a geometrical mesh which becomes finer near the corners and edges. The geometrical mesh becomes a quasi-uniform mesh in the new system of coordinates. We then derive differentiability estimates in these new set of variables and state our main stability estimate theorem using a non-conforming h-p spectral element method whose proof is given in a separate paper. © Indian Academy of Sciences.

Proceedings of the Indian Academy of Sciences: Mathematical Sciences

h-p Spectral element methods for three dimensional elliptic problems on non-smooth domains, part-I: Regularity estimates and stability theorem

Rotary unmanned aerial vehicles are gaining popularity owing to their unique capabilities and flexibility. Multiple experiments and tests are being carried out to make them robust and versatile. This paper elaborates one such attempt of height control and automatic takeoff tests performed on a conventional mini helicopter. A brief description of the vehicle and experiments carried out is included. The simulations for the PID height control implemented on the helicopter using the developed equation for heave dynamics as a plant model have been performed and compared with experimental data and analyzed. The comparison of experimental and simulation is done to correlate theory and what occurs in practice, which would thereby help in improving experimental control. © 2015 by the Asian/Australian Rotorcraft Forum. All rights reserved.

ARF 2015 - 4th Asian-Australian Rotorcraft Forum

Altitude control and automatic takeoff of a conventional mini helicopter

This paper addresses the inverse dynamics of three degrees of freedom (DOF) U-shaped planar parallel manipulator having three legs consisting of prismatic-prismatic-revolute (PPR) joint arrangement in which each leg has one active prismatic joint. This paper also proposes a proportional-derivative (PD) like adaptive sliding mode control combined with a disturbance observer for the motion control of the proposed manipulator. Using this control scheme, the controlled robotic manipulator is transformed into decoupled dynamics, and thus the motion performance is very convenient to quantify. Based on Lyapunov like argument the global asymptotic stability of the proposed closed loop system is proved. Real time experiments performed on the in-house fabricated prototype of the proposed manipulator are provided to substantiate the effectiveness and the improved performance of the proposed controller. The proposed controller performances are also compared with traditional controllers such as proportional integral derivative (PID) controller, sliding mode controller (SMC) and computed torque controller (CTC) © 2015 Elsevier Ltd.

Robotics and Computer-Integrated Manufacturing

Inverse dynamics and control of a 3-DOF planar parallel (U-shaped 3-PPR) manipulator

A thermodynamically consistent phase-field model is formulated for binary-alloy, particularly applicable to the systems which have a significant difference in mobilities of the solute and solvent atoms, e.g., interstitial solutes. The model is based on the mixed-mode of growth which is considered to be the general mode of transformation. As an illustration, the model has been used to simulate austenite to ferrite transformation in one-dimension. The model is made ‘quantitative’ using a different diffusivity-interpolation function without using anti-trapping flux term. The simulation-result is compared with the experimental results, and good agreement with the mixed-mode of growth in the initial stage of the transformation (when the individual nuclei are far apart) has been observed. © 2014, The Minerals, Metals & Materials Society and ASM International.

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

Phase-Field Model for Mixed-Mode of Growth Applied to Austenite to Ferrite Transformation

A helicopter rotor is probably the most complex aeroelastic system. The aeroelastic response problem of a complete rotor involves the blade degrees of freedom and unsteady aerodynamics with three-dimensional effects. The aeroelastic response problem that manifests itself as blade loads, hub loads, or fuselage vibrations has a critical role for rotary-wing vehicles. Aeroelastic response analysis of helicopter rotor requires the development of multidisciplinary comprehensive analysis program which combines structure, aerodynamic and inertial operators. In this study, one such comprehensive analysis model is described. The model includes elastic flap-lag-torsion and axial blade deformations, modified ONERA dynamic stall theory for airloads calculation, and Peters-He dynamic wake theory for inflow computation. In the present study the number of state variables representing the inflow is varied from 3 states to 45 states by increasing the number of harmonics and radial functions, and their effects on helicopter trim, rotor loads and control response are analyzed. Results indicate that there is a clear redistribution of inflow with the increase in number of inflow states. In general there is an increase in the inflow from forward to the aft of the rotor disk with the increase in number of states. It is important to note that there is no significant change in the trim variables with the increase in number of inflow states. However with the inclusion of higher harmonic inflow states, the harmonic contents increase in sectional loads and blade root loads. Higher inflow states are seen to affect helicopter control response to longitudinal input at high speeds. © 2015 by the Asian-Australian Rotorcraft Forum. All rights reserved.

Aeroelastic response of helicopter rotor blade with dynamic wake modeling

The article elaborates the development of gravity-based water filtration systems capable of removing fluoride using natural organic material. In this study, the precipitation and dissolution reaction occurring in suspension of hydroxyapatite (HAP) as addition of fluoride were investigated under well-defined condition. This process is set to occur in a quasi-static gravity-based water filter system. This system is a (pond sand, organic material (gaur seed powder, neem, sesame sawdust, and Ayurvedic waste), water, and HAP mixture) composite ceramic. This article illustrates these ceramic material systems manufactured using distinct permutations of pond sand and organic materials. HAP is introduced into the composite mix of pond sand and organic materials to manufacture some of the sintered ceramic filtration material systems tested here. The fluoride removal efficiency of these variant systems is discussed. The energy dispersive X-ray spectroscopy studies of the ceramics provided the mineral content within the system variants. At high temperatures beyond 600°C, the sintered hydroxyapatite is observed to have a microstructural transformation from amorphous to crystalline. The surface properties of these sintered as well as raw materials used in the production of the ceramic composite are also investigated. A mathematical multivariate regression model is derived providing a relationship between the effectiveness of the water filtration systems as a function of the raw material composition and properties. The Ayurvedic waste material was found to be a good substitute for HAP for fluoride removal. The proposed treatment system is appropriate and suitable approach for fluoride removal in rural areas, because of its simplicity and easy operation and handling. Since Ayurvedic and organic waste materials are easily available at low cost, the proposed method is very suitable for the people living in low-income rural areas of developing countries like India. © 2014 Balaban Desalination Publications. All rights reserved.

Desalination and Water Treatment

Local material composite sintered systems for fluoride removal

Today, Information and Communication Technology (ICT) is ubiquitous. It has touched almost all spheres concerning human survival, growth and development. Agriculture is no exception to it. This paper presents the research initiatives towards improving irrigation efficiency through affordable ICT solutions. It presents experimental results of studies related to improving irrigation efficiency in Semi arid zones in India, using commercially available ICT solutions. It compares between simple microirrigation and microirrigation with ICT (irrigation on demand) and establishes that by using ICT in agriculture, we can increase the irrigation efficiencies by a considerable amount. The paper also presents the development of indigenous wireless sensor node and gateway made from open source hardware and software components. The efforts in this regard show, while maintaining comparable performance, a significant reduction in the cost of wireless sensor devices, when compared to commercially available wireless sensor devices, is achieved. © 2015 IEEE.