Pedro Acosta

Robust integral sliding mode regulator for linear systems with time delay in control input

The paper presents a robustification algorithm for the obtained optimal regulator based on integral sliding mode compensation of disturbances. The general principles of the integral sliding mode compensator design, which yield the basic algorithm applied then to robustify the optimal regulator, are outlined. As a result, the sliding mode compensating control leading to suppression of the disturbances for a finite time is designed. This control algorithm also guarantees finite-time convergence of the disturbed state to the optimally controlled one. The obtained robust control algorithm is verified by simulations in the illustrative example.

Integral Sliding-mode Active Filter Control for Harmonic Distortion Compensation

Abstract An integral sliding-mode control strategy applied to an active power filter is presented. An efficient and simple sliding-mode control is proposed using the d-q reference frame theory, and the integral sliding mode is used to get a practical control action. The proposed approach simplifies the control of a three-phase voltage source inverter employed as the active filter in a three-phase three-wire non-linear load configuration. The active power filter is connected in a shunt configuration in order to compensate for reactive power and mitigate undesired harmonic currents. Simulation and experimental results show the feasibility of the approach.

Natural surface design for sliding mode control with multiple discontinuous inputs

Abstract It is well known that sliding mode control is based on the definition of an invariant manifold, where the system dynamics are forced to in a finite time. Such a manifold is somewhat arbitrarily defined, as long as the system dynamics are stable on it. Computational and control effort may vary depending on selected manifold. Obviously, if a system has naturally acceptable stable dynamics around a desired equilibrium point, no control is needed unless uncertainties or disturbances are present. It would be desirable that if such a system had uncertainties or disturbances, the control effort be designed only to overcome the effect of such factors. For a system with first order dynamics and affine control input, designing a sliding mode control overcoming only such uncertainties or disturbances is a trivial task. When a higher order dynamics system is involved, unit control may be used, where the input control signals are not discontinuous, but when only discontinuous control inputs are available, a design approach is not readily available. In this paper, taking advantage of the natural stable dynamics of a system, a sliding mode control approach is introduced for designing multiple discontinuous control inputs, where the control effort overcomes only uncertainties, disturbances or unstable dynamics. Two illustrative examples are given in order to show the feasibility of the method.

Integral Sliding Mode Controller Design for Stochastic Time-Delay Systems

This paper presents a robustification algorithm for the optimal controller for unobserved linear system states with input delay, linear observations with delay confused with white Gaussian noises, and a quadratic criterion, which is based on integral sliding mode compensation of disturbances. The general principles of the integral sliding mode compensator design are modified to yield the basic control algorithm oriented to time-delay systems, which is then applied to robustify the optimal controller. As a result, the sliding mode compensating control leading to suppression of the disturbances from the initial time moment is designed. The obtained robust control algorithm is verified by simulations in the illustrative example.

Robust integral sliding mode regulator for linear systems with multiple time delays in control input

This paper presents a robustification algorithm for the optimal regulator for linear systems with multiple time delays in control input, based on integral sliding mode compensation of disturbances. The general principles of the integral sliding mode compensator design, which yield the basic algorithm applied then to robustify the optimal regulator, are outlined. As a result, the sliding mode compensating control leading to suppression of the disturbances from the initial time moment is designed. This control algorithm ensures all-time coincidence of the disturbed system state with the optimally controlled one. The designed robust control algorithm is verified by simulations in the illustrative example.

Amplitude estimation of oscillations in delayed relay systems

Time delay does not allow realizing ideal sliding mode, but implies oscillations in the state variable space. An estimation technique is developed for the upper bound of oscillation amplitudes induced by bounded uncertain time delay presence.

Stability Analysis of a Class of Second Order Sliding Mode Control Including Delay in Input

This paper deals with a class of second order sliding mode systems. Based on the derivative of the sliding surface, sufficient conditions are given for stability. However, the discontinuous control signal depend neither on the derivative of sliding surface nor on its estimate. Time delay in control input is also an important issue in sliding mode control for engineering applications. Therefore, also sufficient conditions are given for the time delay size on the discontinuous input signal, so that this class of second order sliding mode systems might have amplitude bounded oscillations. Moreover, amplitude of such oscillations may be estimated. Some numerical examples are given to validate the results. At the end, some conclusions are given on the possibilities of the results as well as their limitations.