S. Janardhanan

Multirate-Output-Feedback-Based LQ-Optimal Discrete-Time Sliding Mode Control

The traditional approach for sliding mode control design has been the design of a controller to achieve a predesigned sliding objective. However, not much research has been carried out on the design of the sliding surface. This note presents a technique for designing a sliding surface such that when confined to the surface, the closed-loop system has optimality in the linear quadratic sense. The paper also proposes a multirate-output-feedback-based controller that leads the system to the aforementioned optimal sliding mode.

Multirate Output Feedback Based Robust Quasi-Sliding Mode Control of Discrete-Time Systems

Over the last few years, the research on discrete-time sliding mode control has received a considerable attention. Unlike its continuous-time counterpart, discrete-time sliding mode control is not invariant in general. In this note, an algorithm is presented for robust discrete-time sliding mode control using the concept of multirate output feedback

Output Feedback Sliding-Mode Control for Uncertain Systems Using Fast Output Sampling Technique

This paper presents a method for achieving quasi-sliding mode for uncertain systems using a fast output sampling control strategy that avoids switching of control and, hence, avoids chattering. This method does not need the system states for feedback as it makes use of only the output samples for designing the controller. Thus, this methodology is more practical and easy to implement. The design technique is illustrated through two numerical examples

On Discretization of Continuous-Time Terminal Sliding Mode

In terminal sliding-mode control, the system states are brought to the origin in finite time using the concept of sliding-mode control. Though the theory of terminal sliding mode is well studied for continuous time systems, a discrete-time terminal sliding mode concept has not been investigated. This note analyses the applicability of terminal sliding-mode control in the discrete-time framework and discusses the problems involved in the discretization of continuous-time terminal sliding mode. The note also suggests a method to approach the discrete-time terminal sliding-mode control problem

Discrete sliding mode control of systems with unmatched uncertainty using multirate output feedback

Systems with uncertainties and disturbances are common in practice. In some cases, these disturbances are unmatched. Moreover, in most cases the entire state information is also not available for control purpose. This note proposes a control algorithm for achieving quasi-sliding mode in discrete-time linear time-invariant (LTI) systems with bounded unmatched uncertainties. A multirate output feedback based strategy is used for this purpose. The proposed algorithm is illustrated through an example.

Advances in Sliding Mode Control

Comprehensive Approach to Sliding Mode Design and Analysis in Linear Systems.- Adaptive Sliding Mode Control.- Decentralised Variable Structure Control for Time Delay Interconnected Systems.- On the Second Order Sliding Mode Approach to Distributed and Boundary Control of Uncertain Parabolic PDEs.- Practical relative degree approach in sliding- mode control.- Higher Order Sliding Mode Based Accurate Tracking of Unmatched Perturbed Outputs.- On the Second Order Sliding Mode Approach to Distributed and Boundary Control of Uncertain Parabolic PDEs.- Practical relative degree approach in sliding- mode control.- Higher Order Sliding Mode Based Accurate Tracking of Unmatched Perturbed Outputs.

A finite-time convergent continuous time sliding mode controller for spacecraft attitude control

In this work a finite time convergent, continuous time sliding mode robust controller is proposed for attitude control of rigid spacecraft. The controller is designed with a new proposed fast terminal sliding mode (FTSM). Finite time reachability to the small neighborhood of sliding surface and faster finite time convergent of system states to equilibrium point is shown using a Lyapunov-type theorem. Simulation results show better convergent performance of the FTSM over terminal sliding mode controller (TSM).

Relay-free Second Order Sliding Mode Control

The paper presents an approach for achieving second order sliding mode in continuous-time systems. The existing methods of second order sliding mode control are based on relay control in the derivative of the input. Such a control, though continuous, is not smooth in close proximity of the sliding surface. The proposed control algorithm achieves second order sliding mode by using a smooth control signal which avoids the use of a relay in the control.

Discrete-time output feedback sliding mode control for time-delay systems with uncertainty

The paper presents an algorithm for the discrete-time output feedback sliding mode control of time delayed systems with uncertainty. The proposed algorithm is capable of handling systems with both state and input delay. The major advantage of the algorithm is that it is based on system output and hence more practical. Moreover, it reduces chattering by avoiding the usage of a switching input.

An efficient control of rigid robotic manipulator with uncertainties using higher order sliding mode control

A robotic manipulator is a highly non-linear system with uncertainties. Sliding mode control provides a method for reliable tracking for such uncertain non-linear systems. In this work, we present an algorithm based on higher order sliding mode concept for tracking and finite time error convergence for articulated robotic manipulators.