Rajiv Kumar Mishra

Smooth sliding mode controller design for robotic arm

This paper seeks to develop simple yet efficient modelling and control scheme for robotic manipulators in joint space wherein a control law is developed based on sliding mode that provides robustness against uncertainties and perturbations and a stability analysis guarantees the asymptotic stability of origin. Given the bounds of disturbance and a switching manifold that enforces trajectory tracking, a control algorithm is presented to drive the states on the switching surface quickly and maintain them thereafter. Further, the system is analyzed for stability and performances and efforts are made to design a controller with smooth characteristics.

Control of a nonlinear continuous stirred tank reactor via event triggered sliding modes

Abstract Continuous Stirred Tank Reactors (CSTR) are the most important and central equipment in many chemical and biochemical industries, that exhibit second order complex nonlinear dynamics. The nonlinear dynamics of CSTR poses many design and control challenges. The proposed controller guarantees a stable closed loop behavior over multiple operating points even in the presence of perturbations and parametric anomalies. An event driven sliding mode control is presented in this work to regulate the temperature and concentration states very close to the equilibrium points of a CSTR. The control is executed only when a predefined condition gets violated and hence, the controller is relaxed when the system is operating under tolerable limits of closed loop performance. A novel dynamic event triggering rule is presented to maintain desired performance with minimum computational cost. The inter event execution time is shown to be lower bounded by a finite positive quantity to exclude Zeno behavior. Sliding mode control (SMC) combined with event triggering scheme retains the inherent robustness of traditional SMC and aids in reducing computational load on the controller involved. Simulation results validate the efficiency of the proposed controller.

Robust nonlinear congestion controller for cognitive radio based wireless network

Under the constraints of limited bandwidth and exponentially rising user demand, there is a dire need to maximize throughput. Maintaining Quality of Service (QoS) in a communication network demands congestion control with high accuracy. This paper focuses on this challenging task that incorporates design of effective congestion controller to reduce packet loss in cognitive radio networks. Limited buffer capacity and bandwidth impose restriction on the performance when number of requests increase. The controller is designed on the notions of sliding mode which is a variable structure control technique known for its robustness and disturbance rejection capabilities. An optimal design strategy is used in development of the controller. The efficiency of the controller is confirmed by numerical simulations.

Sliding mode controller design for high performance of permanent magnet stepper motor

This paper seeks to achieve simple, yet efficient modelling and control scheme for a permanent magnet stepper motor wherein a control law is developed based on sliding mode that provides robustness against uncertainties, parameter variations and perturbations for accurate trajectory tracking of motor position and current. The stability analysis guarantees the asymptotic stability of the origin in finite time. Under bounded disturbance and a switching manifold that enforces trajectory tracking, a control algorithm is presented to drive the states quickly on the stable sliding mode manifold and to constrain them thereafter. Further, efforts have been made to achieve the characteristics of a smooth controller by making the continuous approximation of the discontinuous law.

Robust altitude tracking of a miniature helicopter UAV based on sliding mode

This paper focuses on simple heave dynamics of helicopter UAV for autonomous operations to achieve efficient control scheme based on sliding mode methodology for accurate altitude tracking under both matched and unmatched disturbances. Under fast changing dynamics of the UAV, a control law is developed that provides robustness against uncertainties, parameter variations and perturbations for accurate hovering conditions. The controller guarantees the asymptotic stability of the origin in finite time and the stability of the law has been proved mathematically. Further, efforts are made to smoothen the control signal by making continuous approximation of the discontinuous function in the control law using hyperbolic tangent function.

Consensus in first order nonlinear heterogeneous multi-agent systems with event-based sliding mode control

ABSTRACT This article is aimed at solving leader-following consensus problem with an event-based sliding mode controller. The proposed control technique is partitioned into two parts – a finite time consensus problem and an event-based control mechanism. Leader-following heterogeneous multi-agents of first order having inherent nonlinear dynamics have been analysed to demonstrate efficacy and robustness of the proposed controller. In the first part, states of the follower agents have been attempted to be kept in consistence with those of the virtual leader using sliding mode control. In the second part, an event-based implementation of the control law has been incorporated to minimise the computational load on, and energy expenditure of the computational device equipped with the agents, while ensuring that the desired closed-loop performance of the system is not compromised. The advantage of using such a scheme, i.e. an event-based sliding mode controller, lies in the robustness capabilities of sliding mode controller and reduced computational expense of event-based mechanism. Numerical simulations and mathematical foundations ascertain the effectuality of the controller proposed herein.

Event-triggered sliding mode based consensus tracking in second order heterogeneous nonlinear multi-agent systems

Abstract This work targets the problem of leader following consensus in heterogeneous multi-agent systems described by second order nonlinear dynamics. The controller proposed in the study is an event-based sliding mode controller. Synthesis of the controller has been partitioned into two parts– a finite time consensus problem and an event-based control mechanism. In the first part, the leader following heterogeneous multi-agents of second order having inherent nonlinear dynamics have been addressed and a novel sliding mode reaching law based on inverse sine hyperbolic function has been designed to drive the agents towards consensus. In the second part, an event-based implementation of the control law has been incorporated to minimize computational load on the computational device equipped with the agents and reduce energy expenditure. The triggering rule proposed in this work is dynamic and taking samples respecting this rule ascertains that the desired closed-loop performance of the system is not compromised while exhibiting robustness and high efficacy. The advantage of using such a scheme, i.e., an event-based sliding mode controller is rooted in the robustness capabilities of sliding mode controller and reducing computational expenses via event-based mechanisms. Numerical simulations and mathematical foundations confirm the effectuality of the controller proposed in this study.

Robust and Smooth Nonlinear Control of an Industrial Robot for Automated Pick and Place

This paper seeks to achieve an efficient control scheme that can be applied to industrial pick and place robotic manipulators. The mathematical model of this industrial pick and place system is based on the concept of an inverted pendulum on a moving cart whose movement is restricted in horizontal direction. Inverted pendulum systems are often used to model robotic systems. A sliding mode control has been proposed when the model has been dealt based on this idea. This controller is smooth, robust and rejects the model uncertainties and perturbations. Controls have been formulated independently and efficiency of the robotic system has been proved by numerical simulations.

Robust nonlinear congestion controller for time delayed and uncertain cognitive radio based wireless network

Under the constraints of limited bandwidth and exponentially rising user demand, there is a dire need to maximize throughput. Maintaining Quality of Service (QoS) in a communication network demands congestion control with high accuracy. This paper focuses on this challenging task that incorporates design of effective congestion controller to reduce packet loss in cognitive radio networks. Limited buffer capacity and bandwidth impose restriction on the performance when number of requests increase. The controller is designed on the notions of sliding mode which is a variable structure control technique known for its robustness and disturbance rejection capabilities. An optimal design strategy is used in development of the controller. Physical situations of latency and perturbations are also considered. The efficiency of the controller is confirmed by numerical simulations.