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Articles by T. Nagarajan
Total Records ( 10 ) for T. Nagarajan
  Victor Amirtham , T. Nagarajan , S. Krishnan and Fakhruldin Mohd Hashim
  The research addresses alternate method of actuating a pseudo wrist motion intending to replicate a human supination/pronation motion. The actuation implemented was using a Shape Memory Alloy (SMA) wire as mimicry for a muscular action located within the boundary of the human forearm. Replacing the bone and other muscular structure which act as torsional resilience is the rigid Polyvinyl Chloride (PVC) Split-Tube Flexures. The design of the actuation method was experimented and simulated under laboratory conditions. A fixed size SMA wire was used throughout the experiment. The results gave an insight working of the split-tube flexures under linear angled forces and the behavior of SMA wires under different strain conditions. The study concluded that with use of SMA linear actuation, an angular motion could be achieved. Furthermore the research concludes that split tube flexures can be used as torsional resilience as to be able to return to the initial position, thus removing complex mechanisms.
  T.V.V.L.N. Rao , A.M.A. Rani , T. Nagarajan and F.M. Hashim
  This study presents an analysis of journal bearing lubricated with couple stress fluids considering the effects of a layer adhered to bearing surface. The modified classical Reynold’s equation is derived considering the effects of surface layer and couple stress fluids. In the present study, the effects of couple stresses on the steady state journal bearing performance characteristics are analyzed based on Stokes micro-continuum theory. The Reynold’s boundary conditions are used in the analysis. Results of non-dimensional load capacity and coefficient of friction are presented.
  T. Nagarajan , S. Krishnan , Victor Amirtham , Ahmad Majdi Abdul-Raniand and T.V.V.L.N. Rao
  Pneumatic Artificial Muscle (PAM) as an actuator to create pulling force and bulges mimicking a human muscle contraction. Currently, the method used to manufacture the PAMs is by braiding with artificial fibers. Natural fiber braided PAMs are rarely available for the usage in prosthesis. The novel contribution of this project is to design and develop a desirable low cost and lightweight Pneumatic Artificial Muscle (PAM) actuator using different materials. In this study, the studies are conducted to find the effect of various braided materials such as nylon and Natural Fiber (Silk). The analysis is carried out on actuators of having constant longitudinal length of 140 mm varying the diameter namely 20 and 30 mm. The experiment was set up to collect the length and force variation data of the artificial muscle with various compressed air pressures. The force generated by PAM purely depends on the rate of pressure added and removal from the actuator and is contractile in nature upon inflation. PAM actuator find wide applications in various facets of robotic equipments and industrial automation.
  R. Devarajan , S. Mahendran , Z.A.A. Karim and T. Nagarajan
  The need for cooling in advance thermal systems is ever in demand. The administration of such cooling will need miniaturization of the current pumping system for small-scale use. A valve less pump is one of the methods to create a small microscale flowrate pump. It has intake and outlet on the same side. Advances in fluid mechanics are able to capture the working principles of such pumps and give a close approximation of the pump characteristics. The fundamental aspect that a micropump will endure is analyzed from fluid mechanics analysis, is a key in the development of the model. The sizing and criteria of the pump is set based on fluid equations of mass, momentum and energy. A design is laid out by using computer-aided design (CAD) based on the voltage frequency that will be applied to the piezomaterial. The movement of the material due to current will cause the fluid to move, as the material will act as a diaphragm. The design is then analyzed using computational fluid dynamics (CFD) from the frequency inputs and a steady flow design is simulated. The reading of the small flowrate is analyzed and a proper method of designing the valve less pump is gathered.
  S. Krishna , T. Nagarajan and A.M.A. Rani
  The purpose of this study is to review the current application areas of Pneumatics Artificial Muscle (PAM) actuator. This article analyses the result of the ongoing theoretical and experimental research on the operational behavior of pneumatic muscle such as muscle structure, as well as data on the generated forces. The speed of response of PAM actuator mostly depends upon its shape and size, pressure inputs and outputs. All these factors have impact on the overall force which is generated by the PAMs. The force generated by PAM purely depends on the rate of pressure added and removal from the actuator and is contractile in nature upon inflation. PAM actuators find wide applications in various facets of robotic equipments and industrial automation. They are easy to manufacture, low cost and can be integrated with human operations without any large scale safety requirements.
  R.M. Kuppan Chetty , M. Singaperumal and T. Nagarajan
  This study describes the development of a distributed planning and control strategy for guiding multiple mobile robots in a leader-follower formation framework, which combines together formation planning, navigation and active obstacle avoidance in industrial manufacturing environments. A layered formation control architecture consisting of functional behaviors based on the relative motion states of the robots, classified into two levels is developed. The supervisor level in the framework handles the higher-level missions such as formation and inter-robot communication and the lower level deals with the dynamic control of robots during navigation. Dynamic role switching mechanism through the exchange of leadership is incorporated in this work to tackle the problem of obstacle avoidance in the follower path. The proposed approach is validated through state based laboratory experiments using commercially available robot research platforms and the results obtained are discussed.
  G. Satheesh Kumar and T. Nagarajan
  Cutting with machine tools is an expensive activity, in which even little progress achieved in technology can produce great results. The problem of low stiffness to weight ratio of the rectangular-box-like machine tools has been partially solved with the introduction of Stewart platform. Having six degrees of freedom it executes the positioning of the end-effector in space. The objective of this study is to analyze stiffness of 3-3 Stewart platform using the mathematical model developed based on inverse kinematics for Spiral contours. The set of positions and orientations to be followed by the tool for different contours in terms of the moving platform for maximum stiffness are synthesized. Two planar contours are taken for the purpose of the analysis. The results obtained would serve as a tool in the hands of a design engineer to model the often ignored parameters. This method provides us with set of positions and orientations of the moving platform that should be executed throughout the machining process for a given contour in order to have maximum stiffness of the Stewart platform. The results obtained are to be validated for singularity-free path planning and attempt has to be made to estimate the computational efficiency of the algorithm.
  Abdul Malik Bin Surdi Roslan , Victor Amirtham , T. Nagarajan and Fakhruldin Mohd Hashim
  This research is a study of using a Shape Memory Alloy (SMA) as an actuator in a robotic application for a 6 Degrees of Freedom (DOF) Stewart Platform. Conventional actuators such as hydraulics, pneumatics and mechanical will be replaced by a new breed of technological advancement of SMA wires. The focused area of study is on a mini sized Stewart Platform which eliminates bulky conventional actuators. Hence, SMA will have the distinctive advantages over the other types of actuators. The mini Stewart Platform consists of a fixed base and a platform connected with specially designed SMA actuators along with a counter force spring. The support post for the platform uses a counter force spring material viz. sponges. Further study includes the design of a Pulse Width Modulation (PWM) technique power supply circuit for the controlling the current to increase the temperature of the heat sensitive wires. For the SMA wires, the cooling system serves as an important role to ensure the wires return back to its original length without any damage after they had been stretched out. Kinematic studies have been carried out to achieve required displacements of the platform.
  R.M. Kuppan Chetty , T. Nagarajan , Noh Bin Karsiti and M. Singaperumal
  Modeling and simulation is an important activity in the development of complex control systems such as the multi-robot formation control. This study addresses the use of state based approach to model the complex systems that are employed to perform tightly coupled tasks in an unknown environment. The proposed state based model represents the entire behavior of the complex system by a global state machine or Augmented Finite state machines, which describes the complete intra-object behavior of the system. The methods to model and implement the state machines in the MATLAB-simulink/Stateflow environment are also addressed in this paper. Further, performance of the modeling approach is investigated through simulation studies by considering the multi-robot formation combined with navigation and role switching and are addressed in this study. The simulation result suggests that the state based model and simulation based on Stateflow could be a viable method to model mutli-domain systems such as the highly complex robotic systems with visualization, performance and formalism.
  T.V.V.L.N. Rao , A.M.A. Rani , T. Nagarajan and F.M. Hashim
  The present study evaluates the effects of two-layered long porous journal bearing configuration on improvement in load capacity and reduction in coefficient of friction. The Brinkman model is utilized to model the flow in the porous region. A modified form of Reynolds equation is derived considering two-layered porous region adjacent to the bearing surface. The non-dimensional pressure and shear stress expressions are obtained using the Reynolds boundary conditions. Results of non-dimensional load capacity and coefficient of friction are presented as a function of permeability and thickness of porous layers. Based on the results presented in the study, a low permeability porous layer that adheres to high permeability porous layer on bearing surface could significantly enhance load capacity and reduce coefficient of friction.
 
 
 
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