Browsing by Author "Narendra Nath, S."

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    Active Decoupling Control for a Planetary Coaxial Helicopter Using Force Feedback
    (IEEE Computer Society help@computer.org, 2018) Balakrishnan, B.; Shamrao; Aditya, R.; Narendra Nath, S.; Narayana, S.; Prasad, R.V.
    Drones developed for interplanetary space missions require full autonomy of operations including safe landing and hovering due to the delay in communication. For operation in low atmospheric densities, coaxial helicopters are best suited and they are capable of handling manoeuvres due to their small footprints and ease of operation. However, the dynamics of the helicopter is coupled in lateral axes which need to be compensated for precise control. The present solutions include vision-based tracking in order to decouple the dynamics, which needs additional hardware. In this paper, a decoupling controller is presented that employs an accelerometer-based force feedback system for measuring the undesired forces in off-axis which does not need any additional hardware. The simulation results indicate that the force feedback methodology is very effective in controlling the off-axis drift of the coaxial helicopter. © 2018 IEEE.
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    Experimental investigation on variation of output responses of as cast TiNiCu shape memory alloys using wire EDM
    (ModTech Publishing House office@hotelfloramamaia.ro, 2017) Roy, A.; Narendra Nath, S.; Nedelcu, D.
    The present research study is emphasized on investigation of machining characteristics of TiNiCu shape memory alloys using Wire EDM and analyzes the effect of input process parameters on the quality of the machined surfaces. Complications associated with the machining process results in degradation of surface quality which notably is not avoidable. But proper optimization of the process parameters may help to achieve the desired or near-perfect quality of these machined products. Experiments were conducted as per Taguchi’s L16 orthogonal array considering four input parameters at four levels of operation for Ti50Ni40Cu10, Ti45Ni45Cu10 and Ti40Ni50Cu10 shape memory alloys. Zinc coated brass wire is used as the wire electrode in this study. Material removal rate (MRR) and surface roughness (SR) of the machined samples are considered as the output responses of these alloys. Optimum MRR and SR achieved while machining these alloys are 6.9431 mm3/min and 1.060 µm respectively for Ti50Ni40Cu10. Keeping in mind the productivity of the machining process, formation of recast layer of these alloys are also studied for optimum material removal rate, which led us to the conclusion that Ti45Ni45Cu10 alloy exhibits a surprising aversion towards formation of recast layer as compared to its counterparts. Also, Ti45Ni45Cu10 displayed least average recast layer thickness (RLT) of 9.16 µm compared to 23.93 µm and 21.65 µm for Ti50Ni40Cu10 and Ti40Ni50Cu10 respectively. Pulse on time (120 µs) and wire feed (10 m/min) are found as the most influential Wire EDM process parameters against pulse off time and wire feed for an optimum material removal rate and for a better surface finish, pulse on time (100 µs) and pulse off time (30 µs) against servo voltage and wire feed respectively. © 2017, ModTech Publishing House. All rights reserved.