Infinity Control Theory Research Articles

PI based indirect-type iterative learning control for batch processes with time-varying uncertainties: A 2D FM model based approach

A robust PI based indirect-type iterative learning control (ILC) is proposed in this paper for industrial batch processes with time-varying uncertainties, based on a two-dimensional (2D) Fornasini-Marchesini (FM) model description of the batch process dynamics. An important merit is that the proposed ILC design is independent of the PI tuning in the closed-loop system, owing to that the ILC updating law is only implemented through tuning the set-point of the closed-loop system. By introducing a specified pole location of the closed-loop system, a robust PI controller design is firstly given with the H infinity performance index to maintain the closed-loop robust stability. Then by developing a 2D FM description of the batch operation with the designed PI controller, the control objective of minimizing the tracking error along both the time and batch directions is formulated based on the 2D robust H infinity control theory, such that a robust ILC updating law is determined by solving the linear matrix inequality (LMI) conditions established for holding the 2D system stability. Moreover, the batch-direction convergence rate can be separately tuned via the performance index in the above LMI conditions. An illustrative application to batch injection molding is given to demonstrate the effectiveness and merit of the proposed method.

Modeling of Active Vibration Control in Smart Structures

The paper presents active control of smart structures within a focused frame of piezoelectric applications in active vibration and noise attenuation with potential applications in mechanical and civil engineering. Smart structure has become an increasingly common term describing a structure embedded or bonded with a large number of lightweight active electro-mechanical sensors and actuators. In this paper, we consider the modelling and control issues related to smart structures bonded with piezoelectric sensors and actuators with emphasis on robust control design taking into account structural uncertainties using the H Infinity control theory. The results show that the vibrations can be significantly suppressed by H Infinity controller.

A novel control strategy for four-leg DC-AC converters based on H∞ theory and repetitive control

In this paper, a cascaded voltage-current control strategy for a four-leg DC-AC converter is proposed. The main objective of the proposed controller is to control the DC voltage while tracking the reference output current. The control scheme includes an outer voltage loop and an inner current loop. The voltage loop can provide the maximum power point tracking function used in green power, such as wind and photovoltaic power generation. The inner loop current controller consists of an internal model and a stabilising compensator, which is designed using the H infinity control theory. The internal model contains a delay line and a low-pass filter. To formulate the H infinity problem, two additional parameters are introduced. The stabilising compensator of the internal model is obtained by solving the H infinity problem. The tracking error of the proposed current controller is very small, and the robustness of the controller is very excellent. Experiments are carried out to compare the proposed controller with traditional proportional-resonant and proportional-integral controllers. The results show that the proposed controller has a smaller tracking error with better robustness.

Research of Electrified Railway Harmonic Suppression Based on H-infinity Control

Because of using the nonlinear high-power, single-phase, multi-step full wave or bridge rectifier electric locomotive in electrified railway, the electrified railway traction power supply system has serious power quality problems, which affect safe operation of the electrified railway and impact the local power grid adversely. Aiming at the electrified railway power quality problems, a homogenization model of the inverter is established, and the robustness of active power filter is analyzed based on the H- infinity control theory. Simulation results show that the harmonic control effect of electrified railway is good based on H-infinity control. Under various parameters perturbation, THD is changed relatively small, the system can well follow load changed and has strong robustness. So based on H-infinity control of active power filter in electrified railway harmonic suppression has wide application prospects.

A Robust Reinforcement Learning Control Design Method for Nonlinear System with Partially Unknown Structure

We propose a robust control system which has robustness for disturbance and can deal with a nonlinear system with partially unknown structure by fusing reinforcement learning and robust control theory. First, we solved an optimal control problem without using unknown part of functions of the system, using neural network and the repetition learning of reinforcement learning algorithm. Second, we built the robust reinforcement learning control system which permits uncertainty and has robustness for disturbance by fusing the idea of H infinity control theory with above system.

Robust Output Feedback Guaranteed Cost Control of Nonlinear Stochastic Uncertain Systems Via an IQC Approach

This technical note presents a new approach to constructive output feedback robust nonlinear controller design based on the use of IQCs and minimax LQG control. The approach involves a class of controllers which include copies of the nonlinearities in the controller. The linear part of the controller is synthesized using minimax LQG control theory which is closely related to H infin control theory.

電子制御式可変容量形ポンプへのＨ∞制御理論の適用に関する研究

H infinity control theory was applied to control of a variable displacement piston pump. Angle of the pump's swash plate was detected by means of a position sensor attached on a control piston. The position signal was fed back to a controller and a control input signal was added to a proportional flow control valve so that the control piston position follows the demanded signal. A control system for pump displacement was designed by applying H infinity control theory considering changes in pump speed and load pressure. The control system was examined experimentally on a test bench. Results demonstrated that the system shows stable and quick responses under different pump operating conditions.

An Application of Gain Scheduling Theory to Multi-Machine Stabilization Control

An application of gain scheduling theory to multi machine stabilization control is proposed in this paper. And, a design method of a generator control system based on the gain scheduling theory for multi-machine power systems is proposed. Subsequently a decentralized control is carried out which considers interaction between the generators directly, that is to say, we regard the non-diagonal blocks of the whole system matrix as a disturbance matrix. Moreover, we confirm that the multi input generator control system is effective in using the control system based on the H infinity control theory.

A Method of Designing a Robust Force Controller of a Water-Hydraulic Servo System

The system treated in this paper is a model of a moulding press for a fabrication process of LSI packages. Performance of force control is important to obtain sufficient quality of the moulding. Considering uncertainty caused by flow characteristics of a servo valve and mechanical stiffness of a frame of the press machine, a method of designing a robust force controller by applying H infinity control theory is proposed. Performance of the robust controller is examined using an experimental setup of a water-hydraulic servo system

A solvability condition of an extended control problem using Riccati inequalities

In this paper, we consider an H infinity problem using unstable weighting functions. Such weights are used to achieve asymptoticaly disturbance at enuation and/or asymptotically reference tracking, and they cannot be handled by the standard H infinity control theory. For this problem, we present a necessary and sufficient condition to exist a solution using Riccati inequalities. This condition is derived under no unnecessary assumption to enlarge the applicability to various control problems. Moreover, introducing the assumption that the image of the zero vectors of G12 and G21 are unique, we obtain a LMI condition in order to check the solvability numerically. A numerical example is presented to demonstrate how to calculate a controller.