Satnesh Singh

Bio: Satnesh Singh is an academic researcher from Indian Institute of Technology Delhi. The author has contributed to research in topics: Sliding mode control & Discrete time and continuous time. The author has an hindex of 9, co-authored 30 publications receiving 192 citations. Previous affiliations of Satnesh Singh include Kyungpook National University & National Institute of Technology, Hamirpur.

Fuzzy logic controlled shunt active power filter for reactive power compensation and harmonic elimination

Abstract: Active filters are widely used in electrical distribution system for reactive power compensation and voltage / current harmonic elimination. In this paper, a fuzzy logic controlled, three-phase shunt active filter to improve power quality by compensating reactive power and current harmonics required by a nonlinear load is presented. PI regulator is replaced by fuzzy logic controller to improve the dynamic performance of shunt active filter under varying load conditions. The advantage of fuzzy control is that it is based on defined linguistic rules and does not require any mathematical model of the system unlike the other traditional controller. The compensation process is based on source current sensing only, an approach different from conventional methods. The performance of fuzzy logic controller is compared with PI controller under dynamic load conditions. Simulated studies show that fuzzy controller is found suitable for steady state and transient conditions of load.

Sliding mode control-based linear functional observers for discrete-time stochastic systems

Abstract: Sliding mode control (SMC) is one of the most popular techniques to stabilise linear discrete-time stochastic systems. However, application of SMC becomes difficult when the system states are not available for feedback. This paper presents a new approach to design a SMC-based functional observer for discrete-time stochastic systems. The functional observer is based on the Kronecker product approach. Existence conditions and stability analysis of the proposed observer are given. The control input is estimated by a novel linear functional observer. This approach leads to a non-switching type of control, thereby eliminating the fundamental cause of chatter. Furthermore, the functional observer is designed in such a way that the effect of process and measurement noise is minimised. Simulation example is given to illustrate and validate the proposed design method.

Sliding Mode Control Based Anti-Synchronization Scheme for Hyperchaotic Lu Systems

Abstract: In this paper, design of SMC based controller is proposed for anti synchronization of hyper chaotic 4D Lu systems. To achieve this goal, using the sliding mode control scheme and Lyapunov stability theory, a proportional integral (PI) switching surface is proposed to ensure the stability of the closed-loop error system in sliding motion. Having established the PI switching surface, a sliding mode controller is designed. This controller is effective and guarantees the occurrence of sliding motion and achieves anti-synchronization of master slave hyper chaotic Lu system. Finally, numerical simulations are performed to demonstrate the effectiveness of the proposed control strategy.

Single input sliding mode control for hyperchaotic Lu system with parameter uncertainty

Abstract: In this paper, design of sliding mode controller (SMC) is presented to investigate the stabilization, complete synchronization and adaptive synchronization of four dimensional hyperchaotic Lu systems with parameter uncertainty. To achieve this goal, sliding mode control scheme along with Lyapunov stability theory is utilized. A proportional integral switching surface is proposed to ensure the stability of the closed-loop system in sliding motion. The SMC has been proposed to guarantee the occurrence of the sliding motion. It has also been shown that by proper choice of the adaptation laws for parameters, systems can be synchronized in conventional manner in master-slave configuration, in uncertain environment. The proposed adaptation laws also ensure the convergence of uncertain parameters to their true value in all the cases. Finally, numerical simulations are performed to demonstrate the effectiveness of the proposed approach.

Stochastic variable structure control of discrete time LTI systems with bounded disturbances

Abstract: In this paper, the problem of stochastic variable structure control (SVSC) systems with bounded disturbances is considered and the corresponding SVSC strategies with complete and incomplete state information in presence of bounded disturbances is established. By using the Kalman filter, we are estimating the incomplete state information. Also, stability analysis of bounded disturbances is established. A simulation example is provided to demonstrate the usefulness of the proposed design method.

Modeling and Robust Discrete-Time Sliding Mode Control Design for a Fluid Power Electrohydraulic Actuator (EHA) System

Abstract: This paper studies the design of a robust discrete-time sliding mode control (DT-SMC) for a high precision electro-hydraulic actuator (EHA) system with nonlinear actuator friction. Nonlinear friction in the hydraulic actuator can greatly influence the performance and accuracy of the hydraulic actuators; however, it is difficult to accurately model nonlinear friction characteristics. In this paper, it is proposed to characterize frictions as an uncertainty in the system matrices. Indeed, the effects of variations of the nonlinear friction coefficients are considered as norm bounded uncertainties that span a bounded region to cover a wide range of real actuator friction. For such a discrete-time dynamic model for the EHA system with system matrices uncertainties and a nonlinear term, a sufficient condition for the existence of stable sliding surfaces is proposed by using the linear matrix inequality (LMI) approach. Based on this existence condition, a discrete-time sliding mode controller is developed such that the reaching motion satisfies the discrete-time sliding mode reaching condition for uncertain systems. Simulation and comparison studies on the EHA system model illustrate the effectiveness of the proposed method. The study is simulation based only as it is important to establish the feasibility and stability of the controller before attempting to apply the controller to a physical system.Copyright © 2009 by ASME

Overcoming the Underestimation and Overestimation Problems in Adaptive Sliding Mode Control

Abstract: Underestimation and overestimation problems are commonly observed in conventional adaptive sliding mode control (ASMC). These problems refer to the fact that the adaptive controller gain unnecessarily increases when the states are approaching the sliding surface (overestimation) or improperly decreases when the states are getting far from it (underestimation). In this paper, we propose a novel ASMC strategy that overcomes such issues. In contrast to the state of the art, the proposed strategy is effective even when an a priori constant bound on the uncertainty cannot be imposed. Comparative results using a two-link manipulator demonstrate improved performance as compared to the conventional ASMC. Experimental results on a biped robot confirm the effectiveness and robustness of the proposed method under various practical uncertainties.

Adaptive fuzzy global sliding mode control for trajectory tracking of quadrotor UAVs

Abstract: In this paper, an adaptive fuzzy-based global sliding mode control strategy is proposed for quadrotor unmanned aerial vehicles (UAVs) in robust trajectory tracking against parameter uncertainties and external disturbances. Compared with the conventional sliding mode control, the reaching phase and the control chattering are eliminated in the control scheme, and requirements of the upper bound of the uncertainties are removed. More specifically, in order to counteract the disturbances, the fuzzy system with multiple-input variables and continuous membership functions is adopted rather than the switching term, which softens the control signals greatly. Besides, the use of specific singletons membership functions for the multiple-output fuzzy sets simplifies the defuzzification and reduces the computation burden significantly. Additionally, an adaptive tuner is employed, and the optimal control efforts can be achieved. Finally, comparative flight performances under different controllers for the quadrotor UAVs are demonstrated to verify the effectiveness and superiority of the proposed control approach.

Generalization of Gao's Reaching Law for Higher Relative Degree Sliding Variables

Abstract: In this paper, a generalized discrete time reaching law for sliding variables with arbitrary relative degree is proposed. The reaching law is based on Gao's strategy and ensures higher order switching-type sliding motion, which is a novel concept in the field of discrete time plants. The controller synthesis process is simplified by performing a specific system state transformation. It is demonstrated that the width of the layer to which the representative point of the system is driven decreases as the relative degree of the sliding variable gets bigger. It has further been proven that achieving a narrower quasi-sliding mode band width is reflected in reduced state error. Finally, the reaching phase elimination for variables with arbitrary relative degree is considered. This is obtained by implementing a time-varying sliding surface in a finite number of initial time instants. Uniform ultimate boundedness of all state variables is guaranteed.