Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item A novel pre-processing procedure for enhanced feature extraction and characterization of electromyogram signals(Elsevier Ltd, 2018) Powar, O.S.; Chemmangat, K.; Figarado, S.In the analysis of electromyogram signals, the challenge lies in the suppression of noise associated with the measurement and signal conditioning. The main aim of this paper is to present a novel pre-processing step, namely Minimum Entropy Deconvolution Adjusted (MEDA), to enhance the signal for feature extraction resulting in better characterization of different upper limb motions. MEDA method is based on finding the set of filter coefficients that recover the output signal with maximum value of kurtosis while minimizing the low kurtosis noise components. The proposed method has been validated on surface electromyogram dataset collected from seven subjects performing eight classes of hand movements (wrist flexion, wrist radial deviation, hand close, tripod, wrist extension, wrist ulnar deviation, cylindrical and key grip) with only two pairs of electrodes recorded from flexor carpi radialis and extensor carpi radialis on the forearm. The performance of the MEDA has been compared across four classifiers namely J-48, k-nearest neighbours (KNN), Naives Bayes and Linear Discriminant Analysis (LDA) attaining the classification accuracy of 85.3 ± 4%, 85.67 ± 5%, 76 ± 6% and 91.2 ± 2% respectively. Practical results demonstrate the feasibility of the approach with mean percentage increase in classification accuracy of 20.5%, without significant increase in computational time across seven subjects demonstrating the significance of MEDA in classification. © 2018 Elsevier LtdItem Design and performance comparison of interconnection and damping assignment passivity-based control for vibration suppression in active suspension systems(SAGE Publications Inc., 2021) Sistla, P.; Figarado, S.; Chemmangat, K.; Manjarekar, N.S.; Kallu Valappil, G.This study presents the design of interconnection and damping assignment passivity-based control for active suspension systems. It is well known that interconnection and damping assignment passivity-based control’s design methodology is based on the physical properties of the system where the kinetic and potential energy profiles are shaped, and asymptotic stability is achieved by damping injection. Based on the choice of control variables, special cases of the control law are derived, and tuning of the control law with the physical meaning of the variables is demonstrated along with their simulation results. The proposed control law is experimentally validated on a scaled model of a quarter-car active suspension system with different road profiles, varying load conditions, and noise and delay in the sensor measurements and actuator respectively. The results are compared with that of an uncontrolled system with linear quadratic regulator and sliding mode control. © The Author(s) 2020.Item Selective Lower Order Harmonic Elimination in DC-AC Converter Using Space Vector Approach(Institute of Electrical and Electronics Engineers Inc., 2021) Arumalla, R.T.; Figarado, S.; Panuganti, K.; Nagendrappa, N.A novel space vector-based approach is introduced in this brief to selectively eliminate the lower order harmonics from the DC-AC converter output waveform by making use of double switching clamping sequences. This technique uses a volt-second balance for control of fundamental voltage while using the dwell time rearrangement of the active vector in a sub-cycle to obtain the elimination of fifth or seventh harmonics. Further, the closed-form expression of the dwell time-division coefficient (DTDC) for the active vector dwell time division rearrangement is expressed. The proposed PWM technique is compared with other space vector-based PWM techniques in terms of voltage weighted total harmonic distortion, switching power loss, and lower order harmonic magnitudes. Further, the experimental results are presented to show the effectiveness of the proposed PWM techniques in terms of harmonic elimination. © 2004-2012 IEEE.Item Design and implementation of passivity-based controller for active suspension system using port-Hamiltonian observer(SAGE Publications Ltd, 2023) Sistla, P.; Chemmangat, K.; Figarado, S.The objective of this study is to design and implement an observer for quarter-car active suspension system in Port-Hamiltonian form. A novel state observer is designed for active suspension system modelled in port-Hamiltonian form to estimate the states in presence of road disturbances. The observer is designed considering suspension deflection alone as the output, which is an easily measurable output. Performance of the proposed observer is evaluated experimentally with road disturbance input mimicking a sudden bump and a continuously varying road input, and proven to be effective in minimising the error dynamics in presence of bounded unmodelled disturbances. To prove the effectiveness of the state-estimator, an Interconnection and Damping Assignment Passivity Based Control (IDA-PBC) designed using the desired physical properties of the closed-loop system is implemented using the observer states. Experimental results of the controller implemented using the designed state observer show good improvement in the ride comfort, ride stability and suspension stroke of the active suspension system, which proves the effectiveness of the proposed port-Hamiltonian observer in terms of minimising the error dynamics. © IMechE 2023.