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1

A comparative assessment of hysteresis and dead beat controllers for performances of three phase shunt active power filtering

Panigrahi R., Subudhi B., Panda P. C.

Journal of Power Technologies

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2014

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Vol. 94, nr 4

286--295

EN

This paper presents the performance evaluation of two control techniques, namely Dead Beat Control (DBC) and Hysteresis Band Control (HBC), in a three phase Shunt Active Power Filter (SAPF). The choice and implementation of the current controllers is vital for the achievement of a satisfactory filtering performance. Although these techniques have been applied previously to design SAPF for single phase distorted power system signals, in this paper we extend them to three phase distorted power system signals. In order to test the effectiveness of these two controllers, extensive simulations were conducted using MATLAB/simulink. The results obtained show the superiority of the hysteresis current controller over the dead beat controller in terms of exhibiting fast transient response and computational simplicity. These results are valid with real-time Opal-RT results.

2

Adaptive sliding mode formation control of multiple underwater robots

Das B., Subudhi B., Pati B. B.

Archives of Control Sciences

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2014

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Vol. 24, no. 4

515--543

EN

This paper proposes a new adaptive sliding mode control scheme for achieving coordinated motion control of a group of autonomous underwater vehicles with variable added mass. The control law considers the communication constraints in the acoustic medium. A common reference frame for velocity is assigned to a virtual leader dynamically. The performances of the proposed adaptive SMC were compared with that of a passivity based controller. To save the time and traveling distance for reaching the FRP by the follower AUVs, a sliding mode controller is proposed in this paper that drives the state trajectory of the AUV into a switching surface in the state space. It is observed from the obtained results that the proposed SMC provides improved performance in terms of accurately tracking the desired trajectory within less time compared to the passivity based controller. A communication consensus is designed ensuring the transfer of information among the AUVs so that they move collectively as a group. The stability of the overall closed-loop systems are analysed using Lyapunov theory and simulation results confirmed the robustness and efficiency of proposed controller.

3

Evolutionary computing approaches to optimum design of fuzzy logic controller for a flexible robot system

Subudhi B., Ranasingh S.

Archives of Control Sciences

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2013

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Vol. 23, no. 4

395--412

EN

This paper presents the design of a Fuzzy Logic Controller (FLC) whose parameters are optimized by using Genetic Algorithm (GA) and Bacteria Foraging Optimization (BFO) for tip position control of a single link flexible manipulator. The proposed FLC is designed by minimizing the fitness function, which is defined as a function of tip position error, through GA and BFO optimization algorithms achieving perfect tip position tracking of the single link flexible manipulator. Then the tip position responses obtained by using both the above controllers are compared to suggest the best controller for the tip position tracking.

4

Effects of sliding surface on the performances of adaptive sliding mode slip ratio controller for a HEV

Dash B. K., Subudhi B.

Archives of Control Sciences

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2013

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Vol. 23, no. 2

187--203

EN

Slip ratio control of a ground vehicle is an important concern for the development of antilock braking system (ABS) to avoid skidding when there is a transition of road surfaces. In the past, the slip ratio models of such vehicles were derived to implement ABS. It is found that the dynamics of the hybrid electric vehicle (HEV) is nonlinear, time varying and uncertain as the tire-road dynamics is a nonlinear function of road adhesion coefficient and wheel slip. Sliding mode control (SMC) is a robust control paradigm which has been extensively used successfully in the development of ABS of a HEV. But the SMC performance is influenced by the choice of sliding surface. This is due to the discontinuous switching of control force arising in the vicinity of the sliding surface that produces chattering. This paper presents a detailed study on the effects of different sliding surfaces on the performances of sliding mode based adaptive slip ratio control applied to a HEV.

5

Sliding mode approach to torque and pitch control for an wind energy system using FPGA

Subudhi B., Ogeti P. S.

Archives of Control Sciences

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2012

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Vol. 22, no. 3

285-302

EN

Wind energy, being a fluctuating resource, requires a tight control management to ensure stability when integrated with the grid system. This has triggered interest towards developing advanced controllers. Hence this paper presents the study of a variable speed wind energy conversion system that uses a Double Fed Induction Generator (DFIG). Above rated wind speed, pitch control has been applied and below the rated speed torque control has been adopted. Generator torque control is able to reduce the effects of the pitch actuator limitations. Sliding mode control is applied for torque and pitch control in WECS and it has been implemented in MATLAB SIMULINK and FPGA to achieve control of active and reactive power exchange between the stator of the DFIG and the grid. Performance parameters like pitch angle, active, reactive power, turbine speed, and DC voltage has been compared by using SMC, Hill Climbing (HC) Algorithm and Perturb and Observe (P&O) Algorithm and performance for these three methods has been simulated and implemented in FPGA. Total Harmonic Distortion for all the performance parameters has been reported. Hardware implementation of developed algorithm was accomplished with the help of Xilinx system generator and Xilinx Tool Kit.

6

Comparison of two controllers for directional control of a hybrid electric vehicle

Dash B. K., Subudhi B.

Archives of Control Sciences

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2012

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Vol. 22, no. 2

191-215

EN

Directional response of a vehicle implies changing its direction when sustaining lateral acceleration while moving on the road. From this response, the vehicle's explicit capabilities as well as its contribution to the system performance of the driver/vehicle combination are obtained. In vehicle control literature, handling is often used interchangeably with cornering, turning, or directional response. This paper focuses one aspect of the handling i.e. directional response. Two different controllers, namely a PID controller and a Fuzzy Logic Controller (FLC) for a hybrid electric vehicle (HEV) are designed in this paper to control the vehicle's steering in a smooth lane change maneuver. The performances of the aforesaid two controllers have been studied extensively in this paper. For achieving an improved path tracking and directional response, parameters of both the PID and FLC have been tuned and their performances have been compared. Further, the effect of changing the scale factors in the fuzzy logic approach to obtaining directional response is presented. To validate the above two control performances, a nonlinear simulation model of a HEV is developed and is used in simulation studies. Both the controllers track the desired directional signal efficiently. Both PID and Fuzzy controllers provide competitive performances. Although with the assumption of all parameters of the vehicle available PID controller exhibits slightly better dynamic performance but in the real-world scenario the fuzzy controller is preferred due to its robustness i.e. it does not depend on the parameters of the vehicle.

7

Evolutionary computation approaches to tip position controller design for a two-link flexible manipulator

Subudhi B., Ranasingh S., Swain A. K.

Archives of Control Sciences

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2011

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Vol. 21, no. 3

269-285

EN

Controlling multi-link flexible robots is very difficult compared rigid ones due to inter-link coupling, nonlinear dynamics, distributed link flexure and under-actuation. Hence, while designing controllers for such systems the controllers should be equipped with optimal gain parameters. Evolutionary Computing (EC) approaches such as Genetic Algorithm (GA), Bacteria Foraging Optimization (BFO) are popular in achieving global parameter optimizations. In this paper we exploit these EC techniques in achieving optimal PD controller for controlling the tip position of a two-link flexible robot. Performance analysis of the EC tuned PD controllers applied to a two-link flexible robot system has been discussed with number of simulation results.

8

Stator inter-turn fault detection of an induction motor using neuro-fuzzy techniques

Dash R. N., Subudhi B.

Archives of Control Sciences

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2010

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Vol. 20, no. 3

363-376

EN

Motivated by the superior performances of neural networks and neuro-fuzzy approaches to fault detection of a single phase induction motor, this paper studies the applicability these two approaches for detection of stator inter-turn faults in a three phase induction motor. Firstly, the paper develops an adaptive neural fuzzy inference system (ANFIS) detection strategy and then compares its performance with that of using a multi layer perceptron neural network (MLP NN) applied to stator inter-turn fault detection of a three phase induction motor. The fault location process is based on the monitoring the three phase shifts between the line current and the phase voltage of the induction machine.

9

Differential evolution applied to parameter estimation of induction motor

Subudhi B., Jena D.

Archives of Control Sciences

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2009

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Vol. 19, no. 1

59-80

EN

Control of induction motor drive system requires an exact knowledge of its parameters. Efficient parameter estimation techniques are essential to obtain the parameters such as stator and rotor resistances, leakage and magnetizing inductances, because any mismatch between the actual and computed parameter values may lead to deterioration of control performance of the induction motor drive. In this paper, the differential evolution (DE) strategy - a global optimizer has been exploited for estimation of the above parameters of the induction motor. The main focus of the paper is on the application of the DE strategies to parameter estimation of an induction machine drive system based on the information of its input and output data, where input data comprises the stator voltages and the output data comprises the stator currents. Five different DE strategies were employed for implementing the induction motor parameter estimation schemes. Comparison of the results obtained through an extensive simulation studies on parameter estimations provide an idea how to choose an efficient estimator and to use them for efficiently control the drive.

10

Design of a path following controller for an underactuated AUV

Subudhi B., Atta D.

Archives of Control Sciences

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2009

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Vol. 19, no. 4

437-450

EN

This paper describes a tracking control strategy for an underactuated autonomous underwater vehicle (AUV) on a two dimensional plane (ℜ²). Based on a smooth, inertial, 2D reference trajectory curve, the proposed algorithm uses vehicle dynamics to generate the reference orientation and body-fixed velocities. Following these, required error dynamics are developed. Error dynamics are then stabilized using inverse dynamics control strategy, forcing the tracking error to an arbitrarily small neighborhood of zero. Circular path, as a constant velocity reference trajectory, has been chosen for simulation studies. Simulation results are included to demonstrate the tracking performance of the controller.

11

A comparative study on estimation techniques with applications to power signal frequency

Subudhi B., Ray P. K., Mohanty S. R., Panda A. M.

Archives of Control Sciences

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2008

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Vol. 18, no. 1

89-97

EN

An extended least square (ELS) technique has been proposed in this paper for power system frequency estimation. The validation of the above technique has been made by comparing its performance with the existing techniques such as Kalman filter (KF) and least mean square (LMS) technique etc. It has been observed through a series of simulation studies on frequency estimation that the ELS technique exhibits better performance in comparison to both the LMS and KF methods of power system frequency estimation. In Kalman filter, the determination of covariance matrix is very crucial leading to delay in convergence. LMS algorithm becomes complicated with the incorporation of correlation matrix, which may affect the convergence. On the contrary extended least square algorithm seems to be very simple and attractive without the implementation of covariance and correlation matrix. The feasibility of the ELS algorithm for frequency estimation has been tested with a signal buried with noise. The above estimation technique can be applied in real-time implementation, which will be immensely helpful for the power system protection. A comparative study on performance of the KF, LMS and ELS techniques for power system estimation has been made and included in the paper.