Department of Engineering Design

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

This study uses a low-density solid-state flash lidar for estimating the trajectories of road vehicles in vehicle collision avoidance applications. Low-density flash lidars are inexpensive compared to the commonly used radars and point-cloud lidars, and have attracted the attention of vehicle manufacturers recently. However, tracking road vehicles using the sparse data provided by such sensors is challenging due to the few reflected measurement points obtained. In this paper, such challenges in the use of low-density flash lidars are identified and estimation algorithms to handle the same are presented. A method to use the amplitude information provided by the sensor for better localization of targets is evaluated using both physics-based simulations and experiments. A two-step hierarchical clustering algorithm is then employed to group multiple detections from a single object into one measurement, which is then associated with the corresponding object using a Joint Integrated Probabilistic Data Association (JIPDA) algorithm. A Kalman filter is used to estimate the longitudinal and lateral motion variables and the results are presented, which show that good tracking, especially in the lateral direction, can be achieved using the proposed algorithm despite the sparse measurements provided by the sensor. © 2021 EDP Sciences. All rights reserved.

World University root node

Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME

On Using a Low-Density Flash Lidar for Road Vehicle Tracking

In vehicles, wheel locking and associated instability issues can be prevented by regulating wheel brake torque during braking. In contrast with conventional vehicles, electrified vehicles have both friction and regenerative braking. Typically, pneumatic friction braking is used for Wheel Slip Regulation (WSR) in Heavy Commercial Road Vehicles (HCRVs). However, the pneumatic brake system has a lower bandwidth compared to a regenerative brake system, thereby affecting the braking performance of the HCRV during WSR application. This article proposes an Integral Sliding Mode Control (ISMC) based WSR to exploit the responsiveness of regenerative brakes during braking. The proposed control strategy was evaluated in a hardware-in-loop experimental setup. For different operating conditions, the experimental results conveyed that the proposed braking strategy incorporating regenerative braking reduced the slip ratio tracking root mean square error and stopping distance in the range of 12.13% to 72% and 2.43% to 4% respectively compared to conventional frictional braking (without regenerative braking). © 1967-2012 IEEE.

IEEE Transactions on Vehicular Technology

Electrified Vehicle Wheel Slip Control Using Responsiveness of Regenerative Braking

A robust and a compact fiber optic spectral domain low coherence interferometry system for sensing biological analytes in the biological media such as aqueous humor and gingiva, for non-invasive clinical applications has been proposed in this work. A dual wavelength approach employing two SLED sources with centre wavelengths at 1310 nm in the second overtone and 1589 nm in the first overtone region based on vibrational infrared spectroscopy for selective detection of the analyte is presented. Spectral domain low coherence interferometry provides rapid depth scanning by eliminating interference from neighbouring structures, thereby making it suitable for real time analysis. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Department of Applied Mechanics

Springer Proceedings in Physics

Optical Fiber Based Dual Wavelength Spectral Domain Low Coherence Interferometry for Biomedical Applications

The need for vehicle electrification is growing across the world. However, increased cost and packaging volume considerations arising out of electrification, pose a major barrier to the adoption of electrified vehicles. One of the ways to alleviate cost and packaging volume concerns is through appropriate rating and sizing of the electric powertrain, which is influenced by several factors including power flow magnitude, energy storage capability, thermal limits, voltage and current limits, and packaging requirements. This paper presents practical powerflow considerations in the electric powertrain, associated challenges and potential directions towards reducing the cost and packaging volume of the e-drive system. The target vehicle segment considered for electrification in this study are twowheeled and three-wheeled road vehicles, which are dominant segments of India's vehicle population. Electrification of this segment is expected to result in significant benefits, both for market penetration as well as the environment. The vehicle considered in the study consists of an e-drive system using a 48 V battery pack, connected to a three-phase power electronic inverter supplying a single electric machine for traction. Limits on e-drive system efficiency under these practical conditions for a range of torque-speed operating points are also discussed. © 2021 IEEE.

2021 International Conference on COMmunication Systems and NETworkS, COMSNETS 2021

Power-Flow in Two and Three-Wheeled Road Electric Vehicles: Challenges and Opportunities

Model Predictive Control (MPC) has been used in the automotive domain to control powertrain, suspension, and brakes. Active Vehicle Safety Systems (AVSSs), where the brake system plays a significant role, have gained much impetus since they can potentially reduce road fatalities. Wheel Slip Regulation (WSR) is a popular methodology used in developing AVSSs such as Antilock Brake System and Direct Yaw Control using brake control. This work proposes an MPC based algorithm for WSR utilizing linear longitudinal vehicle and wheel dynamics. The MPC problem is developed as a convex optimization formulation, ensuring that the control problem has a unique solution. The problem is formulated as a Quadratic Program with linear inequality constraints, and an efficient custom MPC solver is developed. The custom MPC solver reduces the number of computations by classifying the matrix operations into three categories, namely, constant matrices, reference-dependent matrices, and feedback-dependent matrices. The proposed MPC is evaluated using IPG TruckMaker®, a vehicle dynamics simulation software, interfaced with MATLAB Simulink®. The braking distance improvement with MPC is in the range of 10% to 40%, and the custom solver decreases the computational time of one iteration by 20 times compared to CVX, a MATLAB tool for convex programming. © 2021 IEEE.

Model Predictive Control of Wheel Slip towards Antilock Brake System Using Convex optimization

The intervehicular distances between the constituent vehicles are highly significant in deciding the fuel economy of vehicular platoon formations. This paper studies the effect of time-headway, which characterizes the intervehicular distance, on the fuel economy of Heavy Commercial Road Vehicle (HCRV) platoons. The study has been conducted using a complete vehicle dynamics model, making it a realistic approach that could be adopted for planning HCRV platoon formations. A relationship between time-headway and fuel cost has been obtained for HCRV platoons operating at various longitudinal speeds. In addition, the aspect of string stability of the platoon to various speed perturbation signals has also been investigated for various timeheadway magnitudes, considering different road conditions. It has been observed that there lies a minimum magnitude of timeheadway to guarantee string stability, depending upon the speed perturbation and road conditions. This study can hence be viewed as a systematic approach for the selection of time-headway for fuel economic and string stable platoon formations under various operating conditions. © 2021 IEEE.

Fuel Economy and String Stability: A Dynamics Based Study on Heavy Road Vehicle Platoons

The classical JMAK model of recrystallization kinetics has been widely used to describe the growth of randomly distributed nuclei under constant driving force. These conditions are not satisfied in many systems. The driving force for growth generally varies with time, and the nuclei are usually not uniformly distributed. In this paper, we present a physically motivated alternative model of recrystallization kinetics, which accounts for the variation of driving force due to recovery and the effect of clustering of the nuclei. The model is based on the growth kinetics of initially circular, strain free nuclei in a deformed matrix. The effect of recovery on the recrystallization kinetics is studied in terms of the parameters governing initial stored energy and the decay rate. The model predicts cessation of recrystallization when the stored energy decreases below a certain critical limit. This cessation depends on both the initial stored energy value as well as the recovery time constant. The effect of clustering of nuclei on recrystallization kinetics is analyzed by considering representative volume elements with different nuclei distributions. It is shown that recrystallization kinetics becomes slower with increased clustering. The results of this mean field model are compared to phase field simulations. Graphical abstract: [Figure not available: see fulltext.]. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.

Department of Metallurgical and Materials Engineering

Fulltext

Journal of Materials Science

A physically based model of the effect of recovery and clustering on recrystallization kinetics

The compression after high-velocity impact (CAI) behavior of pseudo-elastic shape memory alloy (PE-SMA) embedded glass/epoxy composite laminates manufactured via vacuum-assisted resin infusion (VARI) technique was investigated experimentally. High-velocity impact tests were performed on the glass/epoxy composites using an in-house build gas-gun set-up at four different velocities (70, 85, 95, and 105 m/s). To elucidate, the series of damage events undergone on the composites under the high-velocity impact, a high-speed camera was used. Quasi-static compression-after-impact (CAI) tests were performed to evaluate the damage tolerance of different composites subjected to high-velocity impact. Real-time damage progression during the CAI as well as the extent of damage was characterized by using a 2D Digital Image Correlation (DIC) technique. Three different types of embedment configurations of PE-SMA wire, namely, with length variation (35, 70, and 150 mm) and also with and without anchors, were used. The impact test results show that the ballistic limit of anchored PE-SMA composites with an embedment length of 35 mm is 72.72% higher than that of the homogeneous glass/epoxy composites. CAI results indicate that the PE-SMA based composites have better damage tolerance with respect to the homogeneous ones at 70 m/s. In contrast, at higher velocities, the delamination area decreases in the homogenous glass/epoxy composites due to more localized damage and present a higher compressive strength. © 2020 Elsevier Ltd

Composite Structures

Compression after high-velocity impact behavior of pseudo-elastic shape memory alloy embedded glass/epoxy composite laminates

Nanotechnology offers a significant advantage in science, engineering, medicine, medical surgery, foods, packing, clothes, robotics, and computing from the beginning of the twenty-first century. As the potential scientific discovery always contains some good and bad effects on human civilization and the environment, nanotechnology is not an exception. The major drawbacks include economic disruption along with imposing threats to security, privacy, health, and environment. The introduction of the chapter discusses the historical background of nanotechnology. Later it also discusses the advancement of nanotechnology to date with its benefits. Major drawbacks of nanotechnology arise in human health due to the enormous involvement in medicine, food, agriculture, etc. This chapter also deals with environmental nano pollution and its effect on society, highlighting the social-economic disruption due to the rapid use of nanotechnology. Nano pollution affects not only human beings but also other living beings like microorganisms, animals and plants, which are briefly reviewed. This chapter also demonstrates the safety and security of nanotechnological developments, current policy and regulation status, challenges, and future trends. Finally, it is concluded, while nanotechnology offers more efficient power sources, faster and modern computers and technologies, life-saving medical treatments, but due to some negative impacts, it bounds us to think twice before any further advanced technological applications. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.

Springer Series in Biomaterials Science and Engineering

Nanomaterials: An introduction

In the present study, LIBS spectra of biomolecules have been analyzed. The basic biomolecules considered for the analysis were Carbohydrates, Protein and Nucleic acids. It was possible to detect the characteristic emission lines of C, H, N, O, S etc. in the above biomolecules. The samples were prepared for laser ablation as biofilms on glass slides. Interference from substrate was observed in the LIBS spectra of samples. Raman spectra would also be acquired in future studies to obtain molecular information for the biomolecules. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.