Faculty Publications

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Publications by NITK Faculty

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    Modelling operating speed and speed differential on intermediate lane rural roads
    (2012) Sowmya, N.J.; Ravi Shankar, A.U.; Anjaneyulu, M.V.L.R.
    Geometric design elements play an important role in defining the operational efficiency of any roadways. Considerable research has been undertaken worldwide to explore the design consistency concept including identifying potential consistency measures and developing models to estimate them. The main objective of this study is to investigate the design consistency of intermediate lane highways existing in Dakshina Kannada district of Karnataka state based on operating speed and speed differential models. The speed measurements are taken at the mid of tangent section and start of the curve during daylight, off-peak periods and under dry weather conditions. The multiple linear regression analysis technique in SPSS (Statistical Package for Social Sciences) software is used for model estimation. Both operating speed (85th percentile speed) and 85th percentile speed differential measures are used with geometric data to identify the design consistency of horizontal curves. A comparative study is performed to identify the variation between these two speed measures. Operating speed and speed differential models for intermediate lane rural roads are presented in this paper. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.
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    Modeling and design of field programmable gate array based real time robust controller for active control of vibrating smart system
    (Academic Press, 2015) Parameswaran, A.P.; Ananthakrishnan, B.; Gangadharan, K.V.
    The current paper focuses on accurate mathematical modeling of a vibrating piezoelectric laminate cantilever beam theoretically as well as experimentally so as to obtain the best replication of the system dynamics on the software platform for simulation studies. The developed models were tested for accuracy in time as well as frequency domain by employing the sweep sine test. The focus of the study is on the flexural modes of vibrations of the cantilever beam. Here, modeling is focused on the first vibratory mode as it has been observed that the effects of felt vibrations would be maximum in terms of system stability and its operational efficiency when the excitation frequency matches with the first natural frequency of the system (fn1). This was validated by appropriate non-parametric modeling of the smart system by subjecting it to the Impact Hammer test. Development of accurate system models play an important role in designing and testing various control algorithms for reliable active vibration control (AVC). In the final stage, a real time active vibration robust controller was designed using a proportional derivative sliding mode control (PDSMC) technique and deployed on a Field Programmable Gate Array (FPGA) platform. The efficiency of the developed real time controller was proved in time as well as frequency domains by subjecting the closed loop system to harmonic excitations at first natural frequency as well as sweep sine test focussing on the first vibratory mode with the conclusion that the developed controller will function satisfactorily at higher modes of vibrations. © 2015 Elsevier Ltd.
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    Design and development of a model free robust controller for active control of dominant flexural modes of vibrations in a smart system
    (Academic Press, 2015) Parameswaran, A.P.; Ananthakrishnan, B.; Gangadharan, K.V.
    Real physical vibrating smart systems exhibit a lot of nonlinearities in their dynamics. Undesirable vibrations, particularly in the regions of first as well as second resonance, play a very important role in deteriorating the stability of the system as well as its operational efficiency. The work presented in the paper focuses on an analytical technique of mathematical modeling of a vibrating piezoelectric laminate cantilever beam which is considered to be the smart system. The natural frequencies of the vibrating smart system are determined from the ANSYS simulation studies and experimentally, it is found that the vibrations induced voltage is maximum at the first followed by the second natural frequencies. Hence, the smart system is modeled analytically through finite element technique using the Euler-Bernoulli beam theory for the first two flexural modes of vibrations. To account for the possible nonlinearities, a suitable robust controller is designed based on sliding mode technique. Simulation studies on the developed analytical model indicated a high performance of the designed controller in controlling the vibrations at first and second resonance regions. Also, the designed controller was found to be effective in its operations when the excitation varied over a large range covering the first two natural frequencies. In the final stage, the designed robust controller was successfully prototyped on a Field Programmable Gate Array (FPGA) platform using LabVIEW coupled with Compact Reconfigurable Input Output (cRIO-9022) controller configured in its FPGA interface mode and the resulting robust FPGA controller successfully controlled the occurring system vibrations. © 2015 Elsevier Ltd.
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    Parametric modeling and FPGA based real time active vibration control of a piezoelectric laminate cantilever beam at resonance
    (SAGE Publications Inc., 2015) Parameswaran, A.P.; Gangadharan, K.V.
    The operational efficiency and life of mechanical systems/structures depends to a large extent on their vibration control. Continuously occurring vibrations on the systems can cause fatigue and the effects of these vibrations are particularly severe if they occur at a frequency matching with that of the concerned systems natural frequency - a stage called resonance. This paper focuses on achieving active vibration control of a smart cantilever beam at its first resonant frequency as it is at this stage that maximum damage to the system performance is expected. The smart system is modelled in the parametric domain using finite element modeling techniques and the obtained model is validated through experimental means. The active vibration control is achieved by employing two control algorithms namely - output feedback and error based control through general purpose operating system (LabVIEW on Windows 7) as well as in real time operating system (LabVIEW FPGA coupled with compact reconfigurable input output modules) and the performances are compared thereby justifying the importance of the deterministic and reliable real time control over the usual PC based control in experimental studies. © The Author(s) 2014.