Yan Bai

Novel delay-partitioning stabilization approach for networked control system via Wirtinger-based inequalities

This paper studies the problems of stability analysis and state feedback stabilization for networked control system. By developing a novel delay-partitioning approach, the information on both the range of network-induced delay and the maximum number of consecutive data packet dropouts can be taken into full consideration. Various augmented Lyapunov-Krasovskii functionals (LKFs) with triple-integral terms are constructed for the two delay subintervals. Moreover, the Wirtinger-based inequalities in combination with an improved reciprocal convexity are utilized to estimate the derivatives of LKFs more accurately. The proposed approaches have improved the stability conditions without increasing much computational complexity. Based on the obtained stability criterion, a stabilization controller design approach is also given. Finally, four numerical examples are presented to illustrate the effectiveness and outperformance of the proposed approaches.

Improved stability and stabilization design for networked control systems using new quadruple-integral functionals

This paper investigates stability analysis and stabilization for networked control systems. By a refined delay decomposition approach, slightly different Lyapunov-Krasovskii functionals (LKFs) with quadruple-integral terms and augmented vectors containing triple-integral forms of state are constructed. New integral inequalities are proposed to estimate the cross terms from derivatives of the LKFs, which can be proved to offer tighter bounds than what the Jensen one produces theoretically. Moreover, the non-strictly proper rational functions in deriving process are fully handled via reciprocally convex approach. A state feedback controller design approach is also developed. Numerical examples and applications to practical power and oscillator systems demonstrate the superiority of the proposed criteria in conservatism reduction compared to some existing ones.

Further results on stabilization for interval time-delay systems via new integral inequality approach

This paper investigates the stability and stabilization problems for interval time-delay systems. By introducing a new delay partitioning approach, various Lyapunov-Krasovskii functionals with triple-integral terms are established to make full use of system information. In order to reduce the conservatism, improved integral inequalities are developed for estimation of double integrals, which show remarkable outperformance over the Jensen and Wirtinger ones. Particularly, the relationship between the time-delay and each subinterval is taken into consideration. The resulting stability criteria are less conservative than some recent methods. Based on the derived condition, the state-feedback controller design approach is also given. Finally, the numerical examples and the application to inverted pendulum system are provided to illustrate the effectiveness of the proposed approaches.

A generalized double integral inequalities approach to stability analysis for time-delay systems

Abstract In this paper, the stability analysis for time-delay systems is investigated. Firstly, further improved double integral inequalities in the forms of infinite series are developed for estimation of the derivatives of triple integral terms. Comparing with the recently introduced Wirtinger-based, refined Jensen and auxiliary function-based double integral inequalities, the estimation gaps of the proposed ones are ever-shrinking with increase of the intermediate terms without requiring any free-weighting matrix. Then, by constructing a triple integral type of Lyapunov–Krasovskii functional (LKF), some stability conditions for time-delay systems are established. By virtue of the new inequalities, the derived criteria are less conservative and more computationally attractive than some existing works. Finally, the improvement and effectiveness of the proposed approaches are demonstrated via the numerical examples.

New H∞ control approaches for interval time-delay systems with disturbances and their applications.

In this paper, the H∞ performance and control problems for linear systems with interval state or input delays and disturbances are investigated. In order to exploit more information on the delay range, the quadruple -integral terms and quadratic forms of triple integrals are introduced into the Lyapunov-Krasovskii functional (LKF). Particularly, an improved integral inequality is developed for estimation of the cross terms in triple-integral type, which displays significant improvement over the Wirtinger inequality. As a result, a less conservative H∞ performance criterion is derived without requiring many slack variables. Based on the criterion, the H∞ controller design approaches are obtained. Besides the numerical examples, the applications to the practical systems are also provided to illustrate the effectiveness of the proposed approaches.

Improved Stability Analysis for Delayed Neural Networks

In this brief, by constructing an augmented Lyapunov–Krasovskii functional in a triple integral form, the stability analysis of delayed neural networks is investigated. In order to exploit more accurate bounds for the derivatives of triple integrals, new double integral inequalities are developed, which include some recently introduced estimation techniques as special cases. The information on the activation function is taken into full consideration. Taking advantages of the proposed inequalities, the stability criteria with less conservatism are derived. The improvement of the obtained approaches is verified by numerical examples.

On an LAS-integrated soft PLC system based on WorldFIP fieldbus

Communication efficiency is lowered and real-time performance is not good enough in discrete control based on traditional WorldFIP field intelligent nodes in case that the scale of control in field is large. A soft PLC system based on WorldFIP fieldbus was designed and implemented. Link Activity Scheduler (LAS) was integrated into the system and field intelligent I/O modules acted as networked basic nodes. Discrete control logic was implemented with the LAS-integrated soft PLC system. The proposed system was composed of configuration and supervisory sub-systems and running sub-systems. The configuration and supervisory sub-system was implemented with a personal computer or an industrial personal computer; running subsystems were designed and implemented based on embedded hardware and software systems. Communication and schedule in the running subsystem was implemented with an embedded sub-module; discrete control and system self-diagnosis were implemented with another embedded sub-module. Structure of the proposed system was presented. Methodology for the design of the sub-systems was expounded. Experiments were carried out to evaluate the performance of the proposed system both in discrete and process control by investigating the effect of network data transmission delay induced by the soft PLC in WorldFIP network and CPU workload on resulting control performances. The experimental observations indicated that the proposed system is practically applicable.

Optimized combustion system in coal-fired boiler: using optimization control and fieldbus

This paper presented a comprehensive design and implementation of control and optimization for the combustion system in heat-supplying boilers based on a fieldbus, mainly including the air-to-fuel ratio optimization algorithm based on a PID controller and soft measurement methodology for airflow based on the orifice nature of the air pre-heater. After process description and general control schemes were presented, measurement and control principles for the system were given. After an optimization algorithm for air-to-fuel ratio with constant step was introduced briefly, an adaptive optimization algorithm based on a PID controller was proposed, and then detailed design was presented. Advantages of the proposed adaptive optimization algorithm can be seen after comparison with a former algorithm. Approaches for the soft measurement of airflow in a boiler system based on differential air pressure between the inlet and outlet of the air pre-heater and that of fuel were presented. The complete control strategie...This paper presented a comprehensive design and implementation of control and optimization for the combustion system in heat-supplying boilers based on a fieldbus, mainly including the air-to-fuel ratio optimization algorithm based on a PID controller and soft measurement methodology for airflow based on the orifice nature of the air pre-heater. After process description and general control schemes were presented, measurement and control principles for the system were given. After an optimization algorithm for air-to-fuel ratio with constant step was introduced briefly, an adaptive optimization algorithm based on a PID controller was proposed, and then detailed design was presented. Advantages of the proposed adaptive optimization algorithm can be seen after comparison with a former algorithm. Approaches for the soft measurement of airflow in a boiler system based on differential air pressure between the inlet and outlet of the air pre-heater and that of fuel were presented. The complete control strategies for the designed system were given. Implementation of the whole system by a Foundation Fieldbus, including structure design for the control system and soft configurations design for the proposed optimization algorithm, were presented at length. Control effects of the designed system were given, demonstrating tat the design of the whole system was a success by running it reliably for a long time. Some important conclusions on the proposed methodologies and designs in measurement and control using the fieldbus in combustion control were presented at the end of the paper.

A Boiler Combustion Control System with Combustion Ratio Optimisation and Soft Measurements

The level of automation in boilers is relatively low and conventional control systems based on analogue instruments with dashboards are still widely used today. Investigation has shown that heat supply boilers without any automatic measurement and control account for nearly 50% of the total number; and that by means of conventional dashboard-based solution accounts for 75-80% around the world. Some serious problems in the control of medium and small capacity boilers are: 1. Mostly, combustion in boilers is manually controlled. 2. Manual operations in the running of combustion system are notoriously complex, often causing systems breakdown. 3. Some semi-automatic control systems based on analogue instruments and devices often lead to degradation in control effect and low reliability. 4. Self-diagnosis and test information from fields are unavailable with analogue communication applied in field, making the system monitoring and maintenance a heavy workload. 5. Data transmission based on point-to-point topology in field within control systems makes wiring and installation of systems a costly, time-and-labour consuming task. The advent and development of fieldbus technology provide ideal solutions to the renovation of factory automation with its field-based digital communication, distributed control and information acquisition. In this paper, we present a comprehensive design and implementation of a system for combustion control based on Foundation Fieldbus (FF). Designs of algorithms, implementations in terms of system architecture and configurations are included. We propose a scheme for optimising air-to-fuel ratio and implement a number of function blocks in field intelligent devices. We also propose an approach on soft measurement of airflow based on the orifice nature of air pre-heater. This paper is organized as follows. The measurement and control principles for the combustion system and the design and analysis of the proposed soft measurement of airflow are presented in Section 2. Implementation of control with Foundation Fieldbus in aspect of system architecture and soft configuration are covered in Section 3. Control effects are described in Section 4.Conclusions and recommendations are given in Section 5.

An Improved Model for OD and Object Description in Fieldbus Intelligent Instruments Based on Object-Oriented Design

At present, objects dictionary (OD) and object descriptions used in fieldbus intelligent instruments are based on variable-sized storage and constant property values, which constrains the flexibility and portability in data access and modularization and encapsulation in system design. In this paper, a kind of universal data structure for object description in OD was presented. Universal management of object description with different types could be realized with the proposed structure. Based on principle and methodology of Object-Oriented Design (OOD), an improved model for object description was proposed. In the improved model, constant value used in object code field of object description is replaced by function pointer pointing to object instance handler for data process of object instances belonging to the same class. Universal function structure is used for all class object instance handlers for different classes but instances belonging to different classes are manipulated differently with their own handlers. The improved model for OD and object description was proven effective and efficient by the practice of development and design of intelligent instruments in distributed control network.