30,439 research outputs found
Switched Integral Suboptimal Second-Order Sliding Mode Control
This paper presents a switched formulation of the suboptimal second-order integral sliding mode control law that has recently appeared in the literature. The integral approach maintains the good properties of the Suboptimal Second Order Sliding Mode (SSOSM) algorithm in terms of chattering alleviation, but, in addition avoids the reaching phase and keeps the controlled system trajectory on the sliding manifold since the initial time instant. Besides these features, the switched formulation adapts the control gains in different regions of the state space, providing the flexibility needed to accommodate different design objectives when moving towards the desired equilibrium. The paper discusses the properties of the proposed algorithm on a realistic example, that is the lateral dynamics control of a ground vehicle in which the yaw-rate tracking is typically made difficult by parametric uncertainties and nonlinear effects arising with large steering angles
Discrete-time exponentially stabilizing fuzzy sliding mode control via lyapunov's method
The exponentially stabilizing state feedback control algorithm is developed by Lyapunov's second method leading to the variable structure system with chattering free sliding modes. Linear time-invariant discrete-time second order plant is considered and the control law is obtained by using a simple fuzzy controller. The analytical structure of the proposed controller is derived and used to prove exponential stability of sliding subspace. Essentially, the control algorithm drives the system from an arbitrary initial state to a prescribed so-called sliding subspace S, in finite time and with prescribed velocity estimate. Inside the sliding subspace S, the system is switched to the sliding mode regime and stays in it forever. The proposed algorithm is tested on the real system in practice, DC servo motor, and simulation and experimental results are given
Discrete-Time Exponentially Stabilizing Fuzzy Sliding Mode Control via Lyapunov’s Method
The exponentially stabilizing state feedback control algorithm is developed by Lyapunov’s second method leading to the variable structure system with chattering free sliding modes. Linear time-invariant discrete-time second order plant is considered and the control law is obtained by using a simple fuzzy controller. The analytical structure of the proposed controller is derived and used to prove exponential stability of sliding subspace. Essentially, the control algorithm drives the system from an arbitrary initial state to a prescribed so-called sliding subspace S, in finite time and with prescribed velocity estimate. Inside the sliding subspace S, the system is switched to the sliding mode regime and stays in it forever. The proposed algorithm is tested on the real system in practice, DC servo motor, and simulation and experimental results are given
Sliding-Mode-Observer-Based Position Estimation for Sensorless Control of the Planar Switched Reluctance Motor
This paper proposes a position estimation method for a planar switched reluctance motor (PSRM). In the method, a second-order sliding mode observer (SMO) is used to achieve sensorless control of a PSRM for the first time. A sensorless closed-loop control strategy based on the SMO without a position sensor for the PSRM is constructed. The SMO mainly consists of a flux linkage estimation, an adaptive current estimation, an observing error calculation, and a position estimation section. An adaptive current observer is applied in the current estimation section to minimize the error between the measured and estimated currents and to increase the accuracy of the position estimation. The flux linkage is estimated by the voltage equation of the PSRM, and the estimated flux linkage is then used to estimate the phase current in the adaptive current observer. To calculate the observing error of the SMO using the measured and estimated phase currents, the observing error of the thrust force is introduced to replace the immeasurable state error of the position and speed of the mover. The sliding surface is designed based on the error of the thrust force, and stability analysis is given. Once the sliding surface is reached, the mover position is then estimated accurately. Finally, the effectiveness of the proposed method for the PSRM is verified experimentally
Two-leg three-phase inverter control for STATCOM and SSSC applications
Flexible ac transmission systems (FACTS) devices are attracting an increasing interest both in power system academic research and in electric utilities for their capabilities to improve steady-state performance as well as system stability. Several converter topologies for FACTS applications have been proposed in the recent literature, even if those based upon voltage source inverters (VSI) seem to be more attractive due to their intrinsic capability to rapidly respond to network changes such as perturbations subsequent to a fault and their property of being immune to resonance problem. In this paper, a new topology for inverter-based FACTS is proposed. This configuration, employing a two-leg three-phase inverter is employed for both series and parallel-connected reactive power compensators. The converter utilizes a modular topology for allowing a satisfaction of electronic components rating. A control strategy based on variable structure control technique with sliding mode is employed to track appropriate reference quantities. Design and control, as well as good tracking performances, are also verified through numerical simulations
New advances in H∞ control and filtering for nonlinear systems
The main objective of this special issue is to
summarise recent advances in H∞ control and filtering
for nonlinear systems, including time-delay, hybrid and
stochastic systems. The published papers provide new
ideas and approaches, clearly indicating the advances
made in problem statements, methodologies or applications
with respect to the existing results. The special
issue also includes papers focusing on advanced and
non-traditional methods and presenting considerable
novelties in theoretical background or experimental
setup. Some papers present applications to newly
emerging fields, such as network-based control and
estimation
One-cycle control of switching converters
A new large-signal nonlinear control technique is proposed to control the duty-ratio d of a switch such that in each cycle the average value of a switched variable of the switching converter is exactly equal to or proportional to the control reference in the steady-state or in a transient. One-cycle control rejects power source perturbations in one switching cycle; the average value of the switched variable follows the dynamic reference in one switching cycle; and the controller corrects switching errors in one switching cycle. There is no steady-state error nor dynamic error between the control reference and the average value of the switched variable. Experiments with a constant frequency buck converter have demonstrated the robustness of the control method and verified the theoretical predictions. This new control method is very general and applicable to all types of pulse-width-modulated, resonant-based, or soft-switched switching converters for either voltage or current control in continuous or discontinuous conduction mode. Furthermore, it can be used to control any physical variable or abstract signal that is in the form of a switched variable or can be converted to the form of a switched variable
H ∞ sliding mode observer design for a class of nonlinear discrete time-delay systems: A delay-fractioning approach
Copyright @ 2012 John Wiley & SonsIn this paper, the H ∞ sliding mode observer (SMO) design problem is investigated for a class of nonlinear discrete time-delay systems. The nonlinear descriptions quantify the maximum possible derivations from a linear model, and the system states are allowed to be immeasurable. Attention is focused on the design of a discrete-time SMO such that the asymptotic stability as well as the H ∞ performance requirement of the error dynamics can be guaranteed in the presence of nonlinearities, time delay and external disturbances. Firstly, a discrete-time discontinuous switched term is proposed to make sure that the reaching condition holds. Then, by constructing a new Lyapunov–Krasovskii functional based on the idea of ‘delay fractioning’ and by introducing some appropriate free-weighting matrices, a sufficient condition is established to guarantee the desired performance of the error dynamics in the specified sliding mode surface by solving a minimization problem. Finally, an illustrative example is given to show the effectiveness of the designed SMO design scheme
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