Control system design for mechanical systems using contractiontheory

Contraction theory is a control system tool based on an exact differential analysis of convergence. After establishing new combination properties of contracting systems, the paper derives new controller and observer designs for mechanical systems such as aircraft and underwater vehicles. The classical nonlinear strap down algorithm is also shown to be marginally contracting. The relative simplicity of the approach stems from its effective exploitation of the systems' structural specificities     

The design of robust control systems for plants with recycle

A combination of Zakian's design criteria for vague infinite-dimensional plants and the author's previous work, which specifies a recycle compensator for plants with recycle, is exploited to design a controller for a plant with recycle when the parameters of the process in the recycle path are subject to variations. The method gives a closed-loop system with guaranteed performance for large variations in process parameters.     

Control design for integrator hybrid systems

The authors define controllability for hybrid systems as the existence of correct control laws that transfer the hybrid plant between predefined subsets of the hybrid state space. A methodology for analyzing controllability and synthesizing control laws for a class of hybrid systems, applicable especially in batch control, is proposed. They use a framework consisting of a hybrid plant and a hybrid controller that interact in a feedback fashion     

Control system design for parametric uncertainty

This paper introduces some recently developed frequency-domain design techniques that are effective in the design of control systems that are required to be robust under parametric uncertainty. We have extended the well-known classical control tools (i.e., Nyquist plot, Bode plot, and Nichols chart) developed for a fixed plant to the domain of families of plants where the uncertain parameter varies in intervals. Using this new family of plots, classical control design techniques can be used to design robust control systems. The technique is illustrated by examples.     

Information system design for real-time multiprocessing systems

Most research on multiprocessing has concentrated on synchronization methods through special language statements and/or operating system capabilities. In contrast, this paper is concerned with identifying and developing system design principles for information systems in a real-time multiprocessing environment. We do not assume that the processes of the system are independent. We identify how interference can occur and show what is necessary to prevent it. Theorems are proven that show how to determine which processes cannot be multiprocessed. These theorems create the basis for determining what portions of a program need to be placed in a critical region. We show that even some disjoint processes may not be multiprocessed. We then identify system design principles that will yield a better system with respect to total throughput time and multiprocessor utilization. Our results do not depend upon any specific synchronization method.     

Control design for chained-form systems with bounded inputs

Discontinuous, time-invariant controllers have been recently proposed in the literature as an alternative method to stabilize nonholonomic systems. These control laws are not continuous at the origin and although they provide exponential rates of convergence, they may use significant amount of control effort, especially if the initial conditions are close to an equilibrium manifold. We seek to remedy this situation by constructing bounded controllers (with exponential convergence rates) for nonholonomic systems in chained form.     

Identification of delay dominant recycle systems

A new identification method for single-input–single-output delay dominant recycle systems is presented in this paper. Identification of recycle systems is similar to that of closed loop systems. However, identification of recycle systems poses certain challenges in that the input-equivalent signal in the closed loop identification is not available for recycle systems. Therefore, special identification routines are required to ensure consistency of recycle and forward models. It is shown that consistent estimates of delay dominant recycle systems can be obtained by treating a delayed output as one of the inputs. Asymptotic variance expressions for the estimates of forward and recycle models are provided. These are then used in designing an optimal excitation signal for recycle systems. The results are illustrated through an industrial example.     

Control design approaches for nonlinear systems using multiple models

It is difficult to realize control for some complex nonlinear systems operated in different operating regions. Based on developing local models for different operating regions of the process, a novel algorithm using multiple models is proposed. It utilizes dynamic model bank to establish multiple local models, and their membership functions are defined according to respective regions. Then the nonlinear system is approximated to a weighted combination of the local models. The stability of the nonlinear system is proven. Finally, simulations are given to demonstrate the validity of the proposed method.     

Control design for a class of nonlinear continuous-time systems

This paper addresses the control design problem for a certain class of continuous-time nonlinear systems subject to actuator saturations. The system under consideration consists of a system with two nested nonlinearities of different type: saturation nonlinearity and cone-bounded nonlinearity. The control law investigated for stabilization purposes depends on both the state and the cone-bounded nonlinearity. Constructive conditions based on LMIs are then provided to ensure the regional or global stability of the system. Different points, like other approaches issued from the literature, are quickly discussed. An illustrative example allows to show the interest of the approach proposed.     

A system design for surveillance systems protecting critical infrastructures

Critical infrastructures are attractive targets for attacks by intruders with different hostile aims. Modern information and sensor technology provides abilities to detect such attacks. The objective of this work is to outline a system design for surveillance systems aimed at protection of critical infrastructures, with the focus on early threat detection at the perimeter of critical infrastructures. The outline of the system design is based on an assessment of stakeholder needs. The needs were identified from interviews with domain experts and system operators. The system design of the surveillance system and the user requirements in terms of capabilities were then determined. The result consists of the system design for surveillance systems, comprising the systems capabilities, the systems structure, and the systems process. The outcome of the work will have an impact on the implementation of the surveillance systems with respect to the sensors utilized, the sensor data algorithms and the fusion techniques.     

Parametric probabilistic transition systems for system design and analysis

We develop a model of parametric probabilistic transition Systems (PPTSs), where probabilities associated with transitions may be parameters. We show how to find instances of the parameters that satisfy a given property and instances that either maximize or minimize the probability of reaching a certain state. As an application, we model a probabilistic non-repudiation protocol with a PPTS. The theory we develop allows us to find instances that maximize the probability that the protocol ends in a fair state (no participant has an advantage over the others). A preliminary version of this paper was presented at SEFM’04 [LMT04]. 05 April 2006     

Control design for a class of nonlinear parameter varying systems

Stabilisation for a class of one-sided Lipschitz nonlinear parameter varying systems is dealt with in this paper. First, the nonlinear parameter varying system is represented as a subsystem of a differential inclusion. Sufficient conditions for exponential stabilisation for the differential inclusion are given by solving linear matrix inequalities. Then a continuous control law is designed to stabilise the differential inclusion. It leads to stabilising the nonlinear parameter varying system. Finally, a simulation example is presented to show the validity and advantages of the proposed method.     

Control design for time-delay systems based on quasi-direct pole placement

A novel method for the determination of controller parameters in a broad class of linear control systems affected by time-delays is presented. This method is based on an appropriate shaping of the spectrum of the closed-loop system. Its application follows two steps. First, a number of rightmost poles, smaller than the number of controller parameters, are directly assigned. This leads to constraints on the controller parameters. By using algebraic techniques a complete parametrization of all controllers satisfying these constraints is obtained. In the second step, the remaining degrees of freedom in the parameter space are used to shift the remaining part of the system spectrum as far to the left as possible. This corresponds to an optimization problem involving a nonsmooth, non-convex objective function. An extensive real-plant example is presented to demonstrate the effectiveness and applicability of the procedure.     

Fuzzy expert system design for operating room air-condition control systems

In this study, a controlled fuzzy expert system (FES) was designed to provide the conditions necessary for operating rooms. For this purpose, existing operating rooms have been studied to see if there are more useful, reliable and comfortable ones. How an operating room can be controlled with FES and its advantages and disadvantages have also been researched. For a theoretically visible FES to show system’s advantage a prototype operating room was built and a suitable configuration was designed. In this system, heat, humidity, oxygen and particles were used as input parameters, and a fresh air entrance and fan circulation were chosen as output parameters. With the help of an expert, appropriate linguistic expressions and the membership function of these expressions were defined. The sensors were classified and sensor information was transferred to computer by means of an interface designed. In order to transfer the data to the system simultaneously, an interface was written in C#. Whether it provides the most suitable control for the system prototype was determined by simulating the operation with varying numbers of patients and operation personnel. In these trials, input, output and other necessary parameters were collected in the computer.In the study, we obtained excellent results in prototype operating room control with FES. The analyses of the results carried out indicated that the controls performed with FES provide more economical, comfortable, reliable and consistent controls and that they are feasible in a real operating room.     

A computer-aided design system for microelectromechanical systems(MEMCAD)

The authors describe the MIT microelectromechanical computer-aided design system (MEMCAD), in which selected commercial software packages are linked with specialized database and numerical programs to allow designers to quickly perform both mechanical and electrical analyses of structures either described directly, or derived from the design specification (mask data plus process flow). The system architecture, the various modules, and their present status are described, and present system performance is demonstrated with several examples     

Heterogeneous system level co-simulation for the design of telecommunication systems

The advanced complexity and heterogeneity of modern telecommunication systems mostly lead to the incorporation of heterogeneous implementation technologies and design styles. Consequently, the design representation of such systems often requires the mixed use of distinct model of computations at different abstraction layers. Therefore, heterogeneous co-simulation is needed in order to enable the effective communication and interaction among the involved models of computation. This paper resolves this issue by proposing the heterogeneous co-modelling of telecom systems based on the combination of SDL semantics with C language running on an instruction set simulator, coupling in that way the specification and the first refinement steps of the co-design flow. The missing test link between the corresponding tools that support the SDL-C co-model is addressed by proposing a heterogeneous co-simulation scheme through the development of a mediator. Finally, the proposed methodology and the efficiency of the built environment are evaluated through a case study associated with the design of the MAC layer of the DECT telecom system.^1,2     

Inverse system design for LPV systems using parameter-dependent Lyapunov functions

This paper addresses the design problem of gain-scheduled inverse systems (GSISs) for linear parameter-varying (LPV) systems, whose state-space matrices are represented as parametrically affine matrices, using parameter-dependent Lyapunov functions (PDLFs), and proposes a method for them via parametrically affine linear matrix inequalities (LMIs). Our method includes robust inverse system (RIS) design as a special case. For RIS design, our method theoretically encompasses the method using constant Lyapunov functions. A design example is included to illustrate our conclusions.     

An expert system for design of spacecraft attitude control systems

In the aspect of further development of investigations in automatic theorem proving, complicated systems modeling and analysis of their control systems and making such systems more intelligent, we consider problems of elaboration of a hybrid expert system (ES) for design of gyromoment system of attitude control for spacecraft.     

An expert system for aided design of ship systems automation

The paper presents a structure and functions of an expert system for aided design of ship systems automation. The system was developed on basis of a detailed analysis of the design process of ship systems automation. The system includes: knowledge bases regarding methods and procedures of ship systems automation design, databases of automated objects, control devices and elements, requirements of classification societies, and a subsystem for simulation investigations co-operating with the Matlab Simulink package and a knowledge base. In the creation of the system the shell expert system Exsys Developer was used. This system is characterised by a rule-oriented representation of knowledge, backward and forward chaining inference methods, various confidence modes to handle uncertain reasoning including fuzzy logic, and possibility of co-operation with other software and databases. The databases were made using the MS Access software.