College of Engineering, Pune

About: College of Engineering, Pune is a based out in . It is known for research contribution in the topics: Computer science & Sliding mode control. The organization has 4264 authors who have published 3492 publications receiving 19371 citations. The organization is also known as: COEP.

Surface Integrity of C-40 Steel Processed with WC-Cu Powder Metallurgy Green Compact Tools in EDM

Abstract: Electric discharge machining (EDM) is an electrothermal process where recast layer on the machined surface and heat-affected (HAZ) zone just below the machined surface are common phenomena. Thus, the assessment of surface integrity in EDM is a very important task. In this study, an attempt was made to modify the surface integrity of C-40 steel in EDM. WC-Cu powder metallurgy (P/M) green compact tools were used so that the tool material could be transferred to the work surface and thereby the surface characteristics could be altered. WC was used as tool material because of its ability to produce a hard layer over the work surface. A detailed experimental study was performed. The effect of various process parameters on the surface characteristics were presented with the support of analyses such as material transfer rate (MTR), tool wear rate (TWR), surface roughness, optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), microhardness testing, etc. It...

Robust Roll Autopilot Design for Tactical Missiles

Abstract: In this paper, a robust roll autopilot based on the extended state observer technique is proposed. The autopilot is robust to uncertainties, external disturbances, the airframe flexibility, and fast unmodeled sensor lags. The external disturbances and the parametric uncertainties in the roll loop are treated as a composite disturbance and the extended state observer is used to estimate the composite disturbance and the states of the system in an integrated manner. The estimated disturbance and the estimated states are used to robustify linear quadratic regulator autopilots designed for nominal systems. The closed-loop stability of the observer-controller combination is proved. Simulation results are presented to demonstrate the efficacy of the extended state observer in estimation of the uncertainties and the states, and in meeting the objectives of the design. Lastly, the proposed design is compared with some well-known designs reported in the literature.

Disturbance-Observer-Based Sensorless Control of PMSM Using Integral State Feedback Controller

Abstract: The objective of this article is to design robust speed control of a permanent magnet synchronous motor (PMSM). The mathematical model of the PMSM is highly nonlinear with uncertainties and disturbances. The most obvious method is to estimate these disturbances and design a robust controller to attenuate the effect of disturbances from the output. In this article, the load torque, which typically occurs as disturbance in the servo system, is estimated using a disturbance observer (DO). A nonlinear model of the PMSM is linearized using the Jacobian linearization around an operating point, and a state feedback controller with an integral term is designed at this operating point. Novelty of the proposed method lies in the way the DO is used to update this operating point, which is similar to the gain scheduling approach. To extend this method for a sensorless operation, a sliding-mode observer is used with the DO in cascade. The proposed scheme is validated using simulations on MATLAB/Simulink and an experimental setup using TMS320F28027. The results show improved performance as compared to traditional methods over a wide range of speed.