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In this paper, we analyze the effects of power lines parameters' uncertainties on the efficiency of a PowerLine Communication (PLC) system. An estimate of the upper and lower bounds' system response due to the uncertainties is given. The analyzed system is schematized as a connection of multiport devices described by their scattering parameter matrices and an adjoint method for sensitivity calculations, based on the use of a wavelet expansion, is used to determine the bounds. The wavelet based sensitivity analysis allows a direct determination of the time domain sensitivity avoiding computationally expensive convolution integral calculations; in addition a fast and accurate bounds calculation is obtained avoiding statistical Monte Carlo simulations. The bounds determination allows the estimate of noteworthy quantities for the tuning of currently used modulation schemes for PLC such as orthogonal frequency-division modulation. Index Terms--Power lines communication, sensitivity analysis, uncertain parameters.

This paper presents a new logic of operation for time overcurrent relays. With the application of the proposed technique, the sensitivity of time overcurrent relays is increased. In order to obtain this, the relay operates with a dynamic pickup setting, such as load current. Additionally, fast operation of overcurrent relays is obtained. The functional structure is described and the logic of overcurrent relay is evaluated under different operative states. We describe the functional structure of the proposed relay and its implementation in laboratory tests. Index Terms--Overcurrent relay, pickup current, sensitivity.

This paper presents an application of an online self-organizing fuzzy logic controller to a boiler-turbine system of fossil power plant. The control rules and the membership functions of the proposed fuzzy logic controller are generated automatically without using a plant model. A boiler-turbine system is described as a multi-input multioutput (MIMO) nonlinear system in this paper. Then, three single-loop fuzzy logic controllers are designed independently. Simulation shows robust results for various kinds of electric load demand changes and parameter variations of boiler-turbine system. Index Terms--Boilers, fuzzy control, self-organizing control.

This paper presents a novel speed control scheme of an induction motor (IM) using fuzzy-logic control. The fuzzy-logic controller (FLC) is based on the indirect vector control. The fuzzy-logic speed controller is employed in the outer loop. The complete vector control scheme of the IM drive incorporating the FLC is experimentally implemented using a digital signal processor board DS-1102 for the laboratory 1-hp squirrel-cage IM. The performances of the proposed FLC-based IM drive are investigated and compared to those obtained from the conventional proportional-integral (PI) controller-based drive both theoretically and experimentally at different dynamic operating conditions such as sudden change in command speed, step change in load, etc. The comparative experimental results show that the FLC is more robust and, hence, found to be a suitable replacement of the conventional PI controller for the high-performance industrial drive applications. Index Terms--Digital signal processor, fuzzy-logic controller, induction motor, PI controller, real-time implementation, speed control.

The development of an automatic deceleration system for a winding machine in a siderurgy factory is presented in this paper. The proposed system controls the speed of a winding machine in order to obtain the optimum stop point in terms of security and fast production. The system is based on a microcontroller and an extremely simple hardware. The system has been tested for two years and results evince a very good mean time between failures. Index Terms--Automatic deceleration, control system, fast production, microcontroller, m.t.b.f. improvement.

The stability, steady-state error analysis, damping factor, and setting time of discrete data drives for computer numerical control (CNC) machine tools are analyzed to obtain the necessary information for the design of a practical system. The stability of the drive is reviewed using Jury's test and the Mitrovic criterion. The variation of damping factor and settling time with respect to system parameters are presented based on the Mitrovic criterion. Index Terms - Computer numerical control-drive control, Mitrovic's criterion.

A Unified Power Flow Controller (UPFC) is a typical FACTS device capable of instantaneous control of three system parameters. This paper presents a basic control system which enables the UPFC to follow the changes in reference values of the active and reactive power supplied from the outer system controller. The analysis is based on the transformation of the three-phase system to the rotating reference frame. As a step closer to a practical application of the UPFC a modified control structure with a predictive control loop and precontrol signal for a dc-voltage control was designed. The new control system offers better stability and transient performance in comparison with the classical decoupled strategy, especially considering the harmonic distortion of the current being controlled. The derived basic control of the UPFC was tested with the NETOMAC program system.

Material productivity, design preciseness, and time to market are becoming critical in motor manufacturing and can be improved by detailed system design analysis and simulation within manufacturing tolerance. Design by analysis and simulation of switched reluctance motor (SRM) systems and the development method of a new design software are the subjects of this paper, with a focus on the main difficulties. The modeling of geometric, electromagnetic, control, mechanical, and thermal concerns is presented. The electromagnetic approaches include lumped-parameter analysis, finite-element analysis, and boundary-element analysis. The aspects of the study include the following: magnetization curves; controller characterization; system simulation; performance prediction; control system dynamics; vibration modes and frequencies; radial magnetic forces, stresses, and vibrations; and dynamic heat distribution and transfer. Index Terms - Design simulation, finite-element analysis, motor design software, switched reluctance motor.

Robustness of closed loop systems, subjected to unmodeled dynamics, using the Generalized Predictive Controller (GPC) is analysed. A stability bound equation for the GPC controller is derived using the small gain theorem and, from the analysis of this equation, guidelines for selecting the order of the observer polynomial T in the GPC are developed. The choice of the polynomial T order is based on the stability bound equation tendency in high frequencies and is a function of the GPC tuning knobs. Different strategies for choosing the polynomial T roots are also included. The aim is to improve robustness. Key words: GPC, robustness, unmodeled dynamics, closed loop stability.

In the cement industry, many optimization systems have been developed and are currently in operation to reduce total production and delivery costs or to optimize the efficiency of equipment investments. This paper deals with some of these optimization systems, which were designed with mathematical programming. Some effective usage of sensitivity analysis and a systems integration approach are also introduced.

The new coupled pickle line and cold mill (CPCM) has been processing steel since December 1991 at Dofasco Inc. in Hamilton, Ontario, Canada. This mill rolls both sheet and tin plate. The work rolls for the last stand are often textured by grit blasting to roll 'matte' finished strip. A new computer-targeted control system was developed for the roll speeds and gaps, specifically for matte rolling. The new set-up system uses Stone's model, which is more appropriate for the limited reductions evident with the rougher rolls. Conventional automatic gauge control (AGC) systems using thickness measurements after the last stand are limited in performance by the effect of long transport delays. These limitations are particularly critical during mill acceleration and deceleration. The use of a thickness gauge before the stand with matte rolls allows the development of AGC systems using shorter control loops for final gauge control. The AGC system uses a Smith predictor for transport lag, (phase shift), compensation. The combination of the shorter AGC loop and the Smith predictor allows higher gains to be used in the control system. This set-up and control system has contributed to Dofasco's position as a market leader in thickness performance.

DART is the high speed, Unix based data acquisition system being developed by Fermilab in collaboration with seven High Energy Physics Experiments [1 - 6!. This paper describes DART run control, which has been developed over the past year and is a flexible, distributed, extensible system for the control and monitoring of the data acquisition systems. We discuss the unique and interesting concepts of the run control and some of our experiences in developing it. We also give a brief update and status of the whole DART system.

In this paper, an integral criterion is developed for overall analysis and appraisal of the performance, reliability and economy of a computer-based control system. A concept of performability is discussed, and the economic optimality is based on the overall benefits from the manufacturer to the user. A case study for a hydroturbine governing system is given. A comparison between different system configurations shows that it is helpful and beneficial to select a system possessing high indices and excellent quality. Keywords: Performance; Function; Reliability; Performability; Economic optimality; Computer-based control system

Currently, neural networks are being used to solve problems related to control. One way to determine the reliability of the neuro-control technique is to test it on a variety of realistic problems. Another way is to compare it directly with existing traditional control techniques, to see whether it works well and where it needs further refinement. In this article, we compare the neuro-control algorithm to three other control algorithms; fuzzy logic control, generalized predictive control, and proportional-plus-integral control. Each of these four algorithms is implemented on a water bath temperature control system. The four systems are compared through experimental studies under identical conditions with respect to set-point regulation, the effect of unknown load disturbances, large parameter variation, and variable deadtime in the system. It is found that the neuro-control system compares well with the other three control systems and offers encouraging advantages. From the results of the experimental studies, however, the best characteristics of each of these different classes of control systems may be combined for realizing a more efficient and intelligent control scheme.

A Superconducting Cyclotron is now under development at LNS-Catania as a part of a heavy ion-facility. The features of the distributed control system of this accelerator and the experiences gained during its functioning Will be reported together with its future improvements.

Temporary faults in database and process control systems are recovered by the use of rollback-recovery technique, which is a backward error-recovery technique. Deadlines generally restrict the rollback-recovery in process-control systems. Hence, the rollback points must be dynamically inserted. The performance of rollback-recovery strategies is studied using the semi-Markov process. When the rollback recovery is implemented, the model determines the mean program completion time for database and process control systems.

A new approach for wide-range optimal reactor temperature control using diagonal recurrent neural networks (DRNN) with adaptive learning rate scheme is presented. The drawback of the usual feedforward neural network (FNN) is that it is a static mapping and requires a large number of neurons and takes a long training time. The usual fixed learning rate based on empirical trial and error scheme is slow and does not guarantee convergence. The DRNN is for dynamic mapping and requires much fewer number of neurons and weights, and thus converges faster than FNN. A dynamic backpropagation algorithm coupled with adaptive learning rate guarantees even faster convergence. The DRNN controller described here includes both a neurocontroller and a neuroidentifier. A reference model which incorporates an optimal control law with improved reactor temperature response is used for training of the neurocontroller and neuroidentifier. Rapid convergence of this DRNN-based control system is demonstrated when applied to improve reactor temperature performance.

Controller robustness is always a major concern. A controller that meets certain performance design objectives cannot be satisfactory unless it can preserve such quality in the presence of expected uncertainties. For nuclear reactors, a controller that preserves stability and performance for a wide range of operating conditions and disturbances is especially desirable. This paper presents the design of a robust controller using the linear quadratic gaussian with loop transfer recovery (LQG/LTR) for nuclear reactors with the objective of keeping a desirable performance for reactor fuel temperature and temperature of the coolant leaving the reactor for a wide range of reactor power. The obtained results are compared to an observer-based state feedback optimal reactor temperature controller. Sensitivity analysis of the dominant closed-loop eigenvalues and nonlinear simulation are used to demonstrate and compare the performance and robustness of the two controllers. The LQG/LTR approach is systematic, methodical, easy to design, and can give improved temperature performance over a wide range of reactor operation.

This paper describes the computer control system of a large hydroelectric powerplant and the reliability improvements made to the. automatic generation control (AGC) and automatic voltage control (AVC) programs. Hardware and software modifications were required to improve the interface between the powerplant and the regional load dispatch office. These modifications, and their impact on the AGC and AVC reliability, are also discussed. The changes that have been implemented are recommended for inclusion in new powerplant computer control systems, and as an upgrade feature for existing control systems.

This paper describes what automatic generation control (AGC) might be expected to do, ;md what may not be possible or expedient for it to do. Tbe purposes and objectives of AGC are limited by physical elements involved in the process and, hence, the relevant characteristics of these elements are described. For reasons given in this paper, it is desired that AGC act slowly and deliberately over tens of seconds or a few minutes. From a perspective of utility operations, there is no particular economic or control purpose served by speeding up tbe AGC action. By this Task Force paper, the System Control Subcommittee is providing a resource to the power engineering community to help guide research into topics related to AGC.

Modern dc converter firing control systems utilize phase locked loop techniques to synchronize valve firing-pulses with the ac voltage. Moreover, these systems are becoming digitally based with computers used to control the process. An EPRI research project has provided insight to the behavior of these important control functions. This paper describes a digitally based firing-pulse synchronizing control system, examines some basic dynamic performance issues, and describes a model suitable for small-signal stability analysis of this discrete-time process.

This paper presents a step-by-step analysis of the performance and stability characteristics of a digitally based dc firing-pulse synchronizing control. The performance of the loop is dependent upon parameters of the ac system, dc system, and the primary dc regulators. The synchronizing loop at the inverter tends to destabilize low frequency modes of the overall system. Control loop filtering is an effective means of stabilizing this interaction.

The VISTA project and its main achievements so far along with the most important objectives that will be reached in 2005 are discussed. Based on the behavior-programming approach for robotic vehicles, the VISTA vehicles' control system comprises a set of hierarchically organized agent programs.

A self-tuning controller for switched reluctance motors is presented. A torque ripple minimizing controller is implemented with online system identification and adaptation technique. The controller uses a nonlinear model of the machine that is updated online using recursive identification algorithm. The real-time approach improves the overall robustness of the system. Experimental results are presented to validate the self-tuning algorithm. Index Terms--Self-timing controller, switched reluctance motor drive, torque-ripple minimization.

The National Spherical Toms Experiment (NSTX) has as one of its primary goals the demonstration of the attractiveness of the spherical toms concept as a fusion power plant. Central to this goal is the achievement of high plasma [Beta](=2[[Mu].sub.0] [is less than] p [is greater than]/[B/sup.2] a measure of the efficiency of a magnetic plasma confinement system). It has been demonstrated both theoretically and experimentally that the maximum achievable [Beta] is a strong function of both local and global plasma parameters. It is therefore important to optimize control of the plasma. To this end a phased development plan for digital plasma control on NSTX is presented. The relative level of sophistication of the control system software and hardware will be increased according to the demands of the experimental program in a three phase plan. During Day 0 (first plasma), a simple coil current control algorithm will initiate plasma operations. During the second phase (Day 1) of plasma operations the control system will continue to use the preprogrammed algorithm to initiate plasma breakdown but will then change over to a rudimentary plasma control scheme based on linear combinations of measured plasma fields and fluxes. The third phase of NSTX plasma control system development will utilize the rtEFIT code, first used on DIII-D, to determine, in real-time, the full plasma equilibrium by inverting the Grad-Shafranov equation. The details of the development plan, including a description of the proposed hardware will be presented.

An energy ramping control system was developed for the PLS storage ring. Basically the ramping process is to increase currents of magnet power supplies. But the real process is never easy because of two requirements; fast ramping and keeping the storage ring optics unchanged. To satisfy these requirements, the energy ramping system took full advantage of the three-layered PLS control system. Twelve machine interface units (MIUs) at the bottom layer synchronously control the magnet power supplies. One subsystem control computer (SCC) at the middle layer generates the synchronization signals and sends them to the MIUs for the synchronous control of the magnet power supplies. Operator computer at the top layer does nothing but simply sending ramping start command to the SCC and MIUs. The broadcasting protocol of MIL-1553B is used for the transmission of the synchronization signals from the SCC to the MIUs. Now we can increase 2.0 GeV beam energy to 2.5 GeV in a few minutes with the ramping control system. This paper describes system structure, synchronization scheme, and control software of the PLS energy ramping control system.

A commercial two-DSP-based board is the basic unit of the on-line computational and control system under development for the multidetector array CHIMERA. The system design includes a small scale parallel and distributed architecture of PCs and DSP boards. The PCs are used both as host computer and interface between user and network. Each PC can host up to three DSP boards. The system is able to accomplish the on-beam control of CHIMERA, by means of the on-line computation of special algorithms, instead of using the usual techniques of special pulses to be sent off-beam. The physical data, collected and organized in UDP packets by the data acquisition system, are read through a 10 Mbit/s Ethernet network. The PC software, running under Windows NT 4.0, is based on threads and assures the communication and program managing as well as the result presentation. The DSP-software is written in C++ and takes care of the communication with the PC and of the computation of algorithms. The preliminary on beam results for the first three wheels (about 100 telescopes), obtained by employing two biprocessor boards located in the PCI bus of a Pentium MMX PC, are also presented.

In this paper, a mechanical sensorless control system is reported for salient-pole brushless dc motor drives or permanent magnetic synchronous motor drives. Here, two new methods are proposed for obtaining the position angle, the accuracy of which affects the operation of the switching devices of the inverter that drives the motor. First, the method for estimating the position angle is proposed. Secondly, the correcting method for reducing the errors involved in the estimation of position angle is given. The experimental results show that the estimated position angles are calibrated automatically, and then the proposed sensorless control system can control the speed and the position angles of the motor precisely. Index Terms--Position estimation, salient-pole brushless dc motor, sensorless control.

It is well known that robotic manipulators are highly nonlinear coupling dynamic systems. It is difficult to establish an appropriate mathematical model for the design of a model-based controller. Although fuzzy logic control has a model-free feature, it still needs time-consuming work for the rules bank and fuzzy parameters adjustment. In this paper, a stable self-organizing fuzzy controller (SOFC) is proposed to manipulate the motion trajectory of a 5-degrees-of-freedom robot. This approach has a learning ability for responding to the time-varying characteristic of a robot. Its control rules bank can be established and modified continuously by online learning with zero initial fuzzy rules. In addition, this control strategy has effectively improved the stability problem of a previous SOFC. The experimental results show that this intelligent controller has a stable learning ability and good motion control capability. Index Terms--Fuzzy control, robotic motion, self-organizing.

The original impedance function is known to lack robustness due to unknown robot dynamic model and the environment. In order to improve that result, a new impedance function is derived which specifies a desired force directly. This results in a new robust robot force tracking impedance control scheme, which employs a neural network as a compensator to cancel out all uncertainties. The proposed neural force control scheme is capable of making the robot track a specified desired force as well as of compensating for uncertainties in environment location and stiffness, and in robot dynamics. Separate training signals for free-space motion and contact-space motion control are developed to train the neural compensator online. The design of the training signals is justified. Simulation studies with a three-link rotary robot manipulator are carried out and the results show excellent force tracking performance. Index Terms--Force control, neural network, robot manipulator.

A manipulator control method using a disturbance observer with no inverse dynamics has been proposed. The order of the disturbance observer affects the performance of control system, because nominalization of plant is dependent on the control object and the order of the disturbance observer. This paper proposes a unique choice of disturbance observers of different order in joint and task space to improve system performance of hybrid position/force control of redundant manipulators. Also, it has been shown that a proper selection of a coefficient of the disturbance observer is capable to improve robust stability, while not influencing basic performance. The proposed strategy can realize acceleration control and second derivative of force control in task space, which realizes robust and precise control of manipulators. Experimental results using a redundant manipulator show the effectiveness of the proposed strategy. Index Terms--Acceleration control, force control, observers, redundant systems, robot dynamics, stability.

Index Terms-- CAD, control systems, root locus design. I. SUMMARY Root locus design is an inherently iterative process by which the poles and zeros of a system are selected to provide a desirable time response. However, trial and error can be greatly reduced using graphical design recipes. With the advent of computer-aided design (CAD) tools, most of the graphical recipes lost their appeal. We provide procedures for the computer implementation of graphical s-domain design recipes. The procedures can be implemented using any computer-aided design package. We discuss lead, lag, lag-lead, proportional integral, proportional derivative, and proportional integral derivative control. Examples are provided.