Department of Mechanical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

This work presents, a robust position tracking control of a 3-degrees of freedom 2PRP-PPR (P: Active Prismatic joint, P: Passive prismatic joint, R; Revolute joint) parallel motion mechanism. For controlling the motion of the defined platform, a simple method to develop a fuzzy logic controller called as robust single input fuzzy logic control (RSIFLC) algorithm is presented and used for the complex workspace trajectory tracking control problem with the existence of outside disturbances, variable uncertainties, and inner noises. The suggested control method comprises two sections: The first section considers a feed-forward expression to increase control action and a disturbance estimator to account for anonymous factors like outer disturbances and un-modeled dynamics. The second section employs single input fuzzy logic control as a feedback component to improve the system’s overall closed-loop stability. The experimental results demonstrate the superiority of the suggested control algorithm over traditional control schemes. © IMechE 2022.

World University root node

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science

A simplified approach to develop fuzzy logic controller with disturbance estimator for control of a planar parallel (2PRP-PPR) motion platform

Patients with muscle atrophy undergo rehabilitation exercises by applying resistive force and obstructing foot movement to strengthen their muscles and engage with their neuromuscular system. This can be successfully accomplished without the intervention of a physiotherapist through the use of passive wearable ankle-foot exoskeleton. The existing devices in the market cannot offer bidirectional and variable resistance rehabilitation. This paper proposes the design and development of a passive ankle rehabilitation exoskeleton for bidirectional resistance training with variable stiffness element for ankle torque variation. The conceptual design of the exoskeleton with a variable stiffness element made of Grade 5 Titanium alloy (Ti6Al4V) has been presented along with its kinematic and static analysis. The fabricated prototype of the device was validated using surface electromyogram (sEMG), and the observation clearly depicted improvement in the signal energy during plantar flexion and dorsiflexion. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Mechanisms and Machine Science

Development of a Passive Ankle-Foot Exoskeleton for Variable Force Resistance Training

This paper presents a graphical user interface system for a lower limb rehabilitation robot. The mechanism considered for this application is a stationary trainer based on Cartesian parallel manipulator. The trainer is configured with three legs of PRRR (prismatic-revolute-revolute-revolute) configuration connected to the end-effector. The end-effector of the mechanism is a footplate to which the subject’s foot can be attached for therapeutic procedures. The interactive simulator is designed primarily for carrying out the therapeutic procedures of PROM (passive range of motion) of the lower limb. Specifically, the application developed can demonstrate the mechanism motion for hip abduction–adduction, hip flexion–extension, knee flexion–extension and gait training. In addition to these options, the simulator also enables the user to vary the subject parameters like thigh and crus lengths. The proposed interactive simulator design is demonstrated and verified using computer-based numerical simulations. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

A Graphical User Interface (GUI) System for a Stationary Trainer Used in Lower Limb Rehabilitation

In the present work, we investigate the accuracy and robustness of our in-house OpenMP parallelized direct-forcing immersed boundary–lattice Boltzmann (DF-IB-LB) solver by undertaking studies on accuracy, discrete conservation, Galilean invariance and quantification of spurious force oscillations (SFO). Our study reveals that DF-IB-LB exhibits first and second-order spatial accuracy for velocity and pressure errors, respectively, for generic moving boundary problems. The method is found to be Galilean invariant, while errors in discrete conservation and SFO decay linearly and superlinearly, respectively, with grid refinement. The numerical simulations with the proposed solver on a vast number of complex moving boundary problems involving imposed and induced motion highlight its efficacy as a fast, robust and accurate framework for single-phase flows with and without fluid–particle interactions. © 2022, The Author(s) under exclusive licence to OWZ.

Computational Particle Mechanics

Computational assessment of immersed boundary–lattice Boltzmann method for complex moving boundary problems

A velocity-coefficient independent pressure correction equation is proposed based on a modified SIMPLE algorithm for the solution of incompressible Navier-Stokes equations. In the conventional approach of SIMPLE, the central velocity coefficient of linearized momentum equation updates with every non-linear iteration within a time step. Since the pressure correction equation is coupled to the velocity coefficient term the pressure matrix coefficients obtained from the discretized pressure Poisson’s equation also get updated. As a consequence, the preconditioning step used to accelerate the convergence of pressure linear system becomes computationally expensive as the preconditioner is computed at every SIMPLE iteration. In the proposed approach this difficulty is circumvented wherein the velocity coefficient term in the pressure correction equation is repositioned with the velocity term such that the pressure matrix coefficients no longer depend on the same. Hence the preconditioner is computed only once at the first non-linear iteration that is stored and re-used for the subsequent iterations thereby reducing the overall CPU time of simulation. © 2023 Taylor & Francis Group, LLC.

Numerical Heat Transfer, Part B: Fundamentals

A velocity-coefficient independent pressure correction equation for accelerated convergence of linear systems in incompressible flows

For any electronic equipment to function properly heat generated in it must be dissipated so that temperature does not rise above the threshold operating limit. In outer space applications, usually the electronic equipment is mounted on to the satellite structure using bolted joints. Thermal contact conductance (TCC) between the base plate of the electronic component and the satellite structure/heat sink plays a critical role in determining the heat transfer rate between them and hence the equilibrium temperature attained by the electronic component. In this work, TCC is compared for an interface formed by an electronic package base plate mounted using a single bolt on to the structure/heat sink plate both made of AA 6061 (an aluminium alloy). The TCC for this configuration under three conditions is compared viz. (a) in vacuum (b) in atmospheric conditions and (c) with thermal interface material (TIM). The vacuum condition represents the actual outer space conditions where there is no convection. Experiments are performed for a fixed bolt torque for all the three conditions. Steady state temperature measurements are obtained at predetermined sensor locations on the top plate using the heat transfer experiments. Higher temperature on the top plate means lower TCC at the interface. © 2023 Begell House Inc.. All rights reserved.

International Heat Transfer Conference

Thermal contact conductance of bolted joint

In this work, the performance of machining Inconel 625 under different sustainable machining conditions was investigated. Dry, minimum quantity lubrication (MQL), nanoMQL and cryogenic cooling techniques were chosen as sustainable cooling methods for this study and the turning experimental runs were performed by varying the cutting speed, feed and depth of cut at different levels to analyze the influence of each parameter along with the cooling environment on the machinability. The performance comparison was performed on the basis of surface roughness, tool flank wear and cutting force. The variation of the responses with respect to process parameters under different cooling environments was compared. The hardness of the workpieces machined under the selected cooling environments was also studied to analyze the influence of the cutting temperature. Cryogenic cooling outperformed the other sustainable cooling methods owing to the high rate of heat dissipation from the machining zone. Adhesion and abrasion were identified as the tool wear mechanisms under all cooling conditions with the help of SEM micrographs and EDS analysis of cutting tool inserts. Chips produced under each environment are also studied to understand the machinability. © 2022 The Society of Manufacturing Engineers

Journal of Manufacturing Processes

Machining performance comparison of Inconel 625 superalloy under sustainable machining environments

This paper describes a simulation-based study in MATLAB/Simulink to select an appropriate controller for the 3-PRRR (P – Prismatic, R – Revolute) Cartesian Parallel Manipulator (CPM) suitable for lower limb rehabilitation therapies. The dynamic performance of the CPM is incorporated into the simulation model through the derived inverse kinematic equations and assigning the dynamic parameters of the CPM through SimMechanics in MATLAB. This study compares the performance accuracy of the Proportional Integral Derivative (PID) controller, Sliding Mode Control (SMC), and Model Predictive Controller (MPC) to enable real-time tracking of the end effector. It is intended to implement the controller with the least error to the 3-PRRR hardware for superior tracking efficiency of the desired trajectory. Finally, the effectiveness of the 3-PRRR CPM for lower limb rehabilitation with the proposed motion controller is simulated and analyzed in Simulink. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Simulation-Based Comparative Study and Selection of Real-Time Controller for 3-PRRR Cartesian Parallel Manipulator

Aluminium matrix composites are being used in high power applications and electronic packaging, so the study of thermal behaviour of them becomes critical. In this work, the thermal conductivity of aluminium–silicon carbide composites with different volume fractions were estimated using finite element model designed by Digimat—a multi-scale material modelling software. The thermal conductivity estimated by FE model was compared with the experimental data given in the literature, and theoretical models are found to be in good agreement. This validation of the FE model ascertains its use in further analysis. It was also concluded that the volume fraction, size and shape of the reinforcement particles and interfacial thermal resistance play a major role in the resultant thermal conductivity of the composites. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Numerical Simulation of Thermal Conductivity of Aluminium–Silicon Carbide Composites

The least squares and Green-Gauss gradient schemes have been traditionally studied as two distinct techniques for gradient computation on unstructured meshes in the literature. In this Letter, we show that the Green-Gauss gradient method can be interpreted as a weighted least squares gradient scheme and that methods of the Green-Gauss family may therefore be encompassed in the larger set of least squares-based gradient schemes. © 2023 Author(s).