Showing papers in "IEEE Transactions on Industrial Electronics in 1994"
TL;DR: The fundamental concepts of Petri nets are introduced to researchers and practitioners, both from academia and industry, who are involved in the work in the areas of modelling and analysis of industrial types of systems, as well as those who may potentially be involved in these areas.
Abstract: Petri nets, as a graphical and mathematical tool, provide a uniform environment for modelling, formal analysis, and design of discrete event systems. The main objective of this paper is to introduce the fundamental concepts of Petri nets to researchers and practitioners, both from academia and industry, who are involved in the work in the areas of modelling and analysis of industrial types of systems, as well as those who may potentially be involved in these areas. The paper begins with an overview of applications of Petri nets, mostly industrial ones. Then, it proceeds with a description of Petri nets, properties, and analysis methods. The discussion of properties is put in the context of industrial applications. The analysis methods are illustrated using an example of a simple robotic assembly system. The performance analysis, using Petri nets, is discussed for deterministic and stochastic Petri nets. The presented techniques are illustrated by examples representing simple production systems. In addition, the paper introduces high-level Petri nets, fuzzy Petri nets, and temporal Petri nets. This is done in the context of application prospects. The paper also briefly discusses some of the reasons restricting the use of Petri nets, mostly, to academic institutions. >
615 citations
TL;DR: The proposed control algorithm is applied to the experimental PM motor drive system, in which one digital signal processor is employed to execute the control algorithms, and several drive tests are carried out.
Abstract: This paper aims to improve efficiency in permanent magnet synchronous (PM) motor drives. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current vector. The control algorithm of the current vector minimizing the electrical loss is proposed and the optimal current vector can be decided according to the operating speed and the load conditions. The proposed control algorithm is applied to the experimental PM motor drive system, in which one digital signal processor is employed to execute the control algorithms, and several drive tests are carried out. The operating characteristics controlled by the loss minimization control algorithm are examined in detail by computer simulations and experimental results. >
391 citations
TL;DR: This work explores the relationships between motor current and back EMF, and identifies minimum torque ripple, maximum efficiency current excitations that can be implemented with finite bandwidth power electronics (current controlled VSI).
Abstract: Permanent magnet motors are usually driven in one of two ways. Sinusoidal currents are applied when the motor has a sinusoidal back EMF, and rectangular currents are applied when the back EMF has a trapezoidal shape. If implemented perfectly, each of these drive schemes is capable of producing ripple-free torque, which is desirable in many applications. However, in reality, permanent magnet motors never exhibit perfectly sinusoidal or trapezoidal back EMFs. Moreover, the power electronics used to drive the motor often has limitations that keep it from producing the required current waveform, especially as speed or load torque increases. In addition to these limitations, a permanent magnet motor often exhibits parasitic cogging torque that directly contributes to torque ripple. This work explores the relationships between motor current and back EMF, and identifies minimum torque ripple, maximum efficiency current excitations that can be implemented with finite bandwidth power electronics (current controlled VSI). >
240 citations
TL;DR: A new type of switching-mode power supply containing no inductors or transformers makes possible the realization of power converters of small size, low weight and high power density, able to be manufactured in IC technology.
Abstract: A new type of switching-mode power supply containing no inductors or transformers is proposed. The controlled transfer of energy from a unregulated DC source to a regulated output voltage is realized through a switched-capacitor (SC) circuit. A duty-cycle control is used; the driving signals of the transistors in the SC circuit are determined by the feedback circuit. The absence of magnetic devices makes possible the realization of power converters of small size, low weight and high power density, able to be manufactured in IC technology. High efficiency, small output voltage ripple and good regulation for large changes in the input voltage and/or load values are other positive features of the new type of DC-to-DC power converter. The input-to-output voltage conversion ratio is flexible; the same converter structure can provide a large range of constant desired values of the output voltage for a given input voltage, by predetermining the steady-state conversion ratio. The frequency response shows good stability of the designed converter. The experimental results obtained by using a prototype of a step-down SC-based DC-to-DC converter confirmed the theoretical expectations and the computer simulation results. >
202 citations
TL;DR: A new approach is proposed that minimizes the total copper and iron losses in a variable speed and/or torque IM drive, while keeping a good dynamic response.
Abstract: The induction motor (IM) is a high-efficiency machine when working close to its rated operating point. However, at torques and/or speeds far from the rated values the efficiency is greatly reduced. In this work a new approach is proposed that minimizes the total copper and iron losses in a variable speed and/or torque IM drive, while keeping a good dynamic response. This method is based on a simple IM model that includes iron losses. The model, which only requires the knowledge of conventional IM parameters, is referred to a field-oriented frame. Using this model, the IM losses are quantified and an algorithm, based on a field-oriented scheme, is deduced. Simulation and experimental results are presented to validate the proposed method. >
181 citations
TL;DR: The three basic types of resonant inverters, the series- loaded, parallel-loaded, and theseries-parallel-loading, are compared using fundamental approximation techniques for their applicability in electronic ballasts operating from a low voltage source.
Abstract: Electronic ballasts must provide enough open circuit voltage to start the fluorescent lamp and current limiting while the lamp is running. Resonant inverters may be utilized in electronic ballasts because of their load-dependent characteristics. The three basic types of resonant inverters, the series-loaded, parallel-loaded, and the series-parallel-loaded, are compared using fundamental approximation techniques for their applicability in electronic ballasts operating from a low voltage source. A parallel-loaded resonant inverter operating slightly above its resonant frequency is selected because of the high voltage gains possible. Operation above the resonant frequency allows zero-voltage turn on of the semiconductor devices. Zero-voltage turn off can be achieved with the addition of lossless snubber capacitors. Experimental results from a lab prototype are used to verify the design procedure. >
168 citations
TL;DR: It is shown that by placing the parallel inductor on the secondary-side, the parasitics of the high-frequency transformer can be used profitably and the converter has load short circuit capability.
Abstract: A series resonant converter modified by adding an inductor in parallel with the transformer primary (or secondary) is presented. This configuration is referred to as an "LCL-type series resonant converter". A simplified steady-state analysis using complex AC circuit analysis is presented. Based on the analysis, a simple design procedure is given. Detailed experimental results obtained from a MOSFET-based 640 W converter are presented to verify the analysis. A narrow variation in switching frequency is required to regulate the output voltage for a very wide change in load, and the converter has load short-circuit capability. It is shown that by placing the parallel inductor on the secondary side, the parasitics of the high-frequency transformer can be used profitably. >
160 citations
TL;DR: A self-organizing fuzzy controller to augment a sliding-mode control (SOFSMC) scheme for a class of nonlinear systems and the results show that both alleviation of chatter and robust performance are achieved.
Abstract: A self-organizing fuzzy controller to augment a sliding-mode control (SOFSMC) scheme for a class of nonlinear systems is proposed. The motivation behind this scheme is to combine the best features of self-organizing fuzzy control and sliding-mode control to achieve rapid and accurate tracking control of a class of nonlinear systems. The chatter encountered by most sliding-mode control schemes is greatly alleviated without sacrificing invariant properties. A stability analysis is presented; the design guidelines and the class of applicable systems are clearly identified. To verify the scheme, the authors performed experiments on its implementation in a magnetic levitation system. The results show that both alleviation of chatter and robust performance are achieved; the advantages of the scheme are indicated in comparison with the conventional sliding-mode design. >
156 citations
TL;DR: A real-time predictive current controller for PWM inverter feeding PM synchronous motor is presented in which the accuracy and the robustness of the control are improved by integral compensation.
Abstract: A real-time current controller for PWM inverter-fed permanent-magnet synchronous motor drives is presented and analyzed. The proposed current control scheme is based on predictive control with a parallel integral loop added to compensate for the inaccuracy of the motor model and for the variations of motor parameters and DC voltage source. The proposed current control scheme is analyzed and its performance is evaluated by computer simulation. An EPROM-based implementation is presented in which calculations and pulsewidth modulation are executed by lookup tables resulting in high-speed operation. The controller performance is evaluated using a prototype l kW PM synchronous servo drive. Experimental results are given and discussed. >
143 citations
TL;DR: This paper surveys three intelligent vehicles developed in Japan, and in particular the configurations, the machine vision systems, and the driving control systems.
Abstract: This paper surveys three intelligent vehicles developed in Japan, and in particular the configurations, the machine vision systems, and the driving control systems. The first one is the Intelligent Vehicle, developed since the mid 1970's, which has a machine vision system for obstacle detection and a dead reckoning system for autonomous navigation on a compact car. The machine vision system with stereo TV cameras is featured by real time processing using hard-wired logic. The dead reckoning function and a new lateral control algorithm enable the vehicle to drive from a starting point to a goal. It drove autonomously at about 10 km/h while avoiding an obstacle. The second one is the Personal Vehicle System (PVS), developed in the late 1980's, which is a comprehensive test system for a vision-based vehicle. The machine vision system captures lane markings at both road edges along which the vehicle is guided. The PVS has another machine vision system for obstacle detection with stereo cameras. The PVS drove at 10-30 km/h along lanes with turnings and crossings. The third one is the Automated Highway Vehicle System (AHVS) with a single TV camera for lane-keeping by PD control. The machine vision system uses an edge extraction algorithm to detect lane markings. The AHVS drove at 50 km/h along a lane with a large curvature. >
141 citations
TL;DR: A novel two-layered fuzzy logic controller for controlling systems with deadzones that exhibits superior transient and steady-state performance compared to usual fuzzy PD controllers and is robust to variations in deadzone nonlinearities.
Abstract: Existing fuzzy control methods do not perform well when applied to systems containing nonlinearities arising from unknown deadzones. In particular, we show that a usual "fuzzy PD" controller applied to a system with a deadzone suffers from poor transient performance and a large steady-state error. In this paper, we propose a novel two-layered fuzzy logic controller for controlling systems with deadzones. The two-layered control structure consists of a fuzzy logic-based precompensator followed by a usual fuzzy PD controller. Our proposed controller exhibits superior transient and steady-state performance compared to usual fuzzy PD controllers. In addition, the controller is robust to variations in deadzone nonlinearities. We illustrate the effectiveness of our scheme using computer simulation examples. >
TL;DR: Criteria to compare LLDs and Petri nets in designing sequence controllers and responding to the changing control requirements are identified and the results reported will help establish Petri net based techniques for discrete-event control of industrial automated systems.
Abstract: Design methods for sequence controllers play a very important role in advancing industrial automation. The increasing complexity and varying needs of modern discrete manufacturing systems have challenged the traditional design methods such as the use of ladder logic diagrams (LLDs) for programmable logic controllers. The methodologies based on research results in computer science have recently received growing attention by academic researchers and industrial engineers in order to design flexible, reusable, and maintainable control software. Particularly, Petri nets are emerging as a very important tool to provide an integrated solution for modeling, analysis, simulation, and control of industrial automated systems. This paper identifies certain criteria to compare LLDs and Petri nets in designing sequence controllers and responding to the changing control requirements. The comparison is performed through a practical system after introducing "real-time Petri nets" for discrete-event control purposes. The results reported in this paper will help: (a) further establish Petri net based techniques for discrete-event control of industrial automated systems; and (b) effectively convince industrial practitioners and researchers that it is worthy and timely to consider and promote the applications of Petri nets to their particular discrete-event control problems. >
TL;DR: A hardware implementation of a fully digital multilayer perceptron artificial neural network using Xilinx Field Programmable Gate Arrays (FPGAs) and a 1 K/spl times/8 EPROM is presented.
Abstract: In this paper, the authors present a hardware implementation of a fully digital multilayer perceptron artificial neural network using Xilinx Field Programmable Gate Arrays (FPGAs). Each node is implemented with two XC3042 FPGAs and a 1 K/spl times/8 EPROM. Training is done offline on a PC. The authors have tested successfully the performance of the network. >
TL;DR: An approach is presented to the speed control of permanent magnet synchronous motors without mechanical transducers through the instantaneous stator flux position and an estimated value of the load angle through a closed-loop state observer.
Abstract: In the present paper an approach is presented to the speed control of permanent magnet synchronous motors without mechanical transducers. The rotor position, which is an essential component of any vector control scheme, is calculated through the instantaneous stator flux position and an estimated value of the load angle. A closed-loop state observer is implemented to compute the speed feedback signal. Experimental results on a laboratory tested motor drive are presented to validate the proposed procedure. >
TL;DR: Real time detection methods of moving vehicles and pedestrians for navigation of the mobile robot are proposed, based on a locomotion strategy, viz. signature-based stereotype motion, which is independent from clothes the pedestrian puts on.
Abstract: Real time detection methods of moving vehicles and pedestrians for navigation of the mobile robot are proposed. The method is based on a locomotion strategy, viz. signature-based stereotype motion. Signature of the moving vehicle is the shadow underneath the vehicle which is darker than any other parts of the asphalt paved road. Signature of the pedestrian is rhythm of walking. Rhythm of walking is unique to the pedestrian, and not influenced by time, weather, sunlight, shadow, and distance. Moreover, it is independent from clothes the pedestrian puts on. The result of experiments verify the validity of the methods. >
TL;DR: The paper presents the implementation of a DSP-based controller for three-phase, space-vector modulated converters that features very high data processing speed, and provides high-quality, low-distortion power converter input currents and output voltages.
Abstract: The paper presents the implementation of a DSP-based controller for three-phase, space-vector modulated converters. The implementation is illustrated for the control of a 2 kW, ZVS matrix power converter-based three-phase PWM rectifier. The controller features very high data processing speed (converter switching frequency of 100 kHz), and provides high-quality, low-distortion power converter input currents and output voltages. The controller can be implemented using only a few standard integrated circuits, providing high reliability and low cost. >
TL;DR: Variable frequency variable voltage operation of a three-phase induction motor in single-phase mode for two common faults of aThree-phase inverter, i.e., open base drive and device short-circuit is considered.
Abstract: Improved reliability and fault tolerant operation of power converter systems are extremely important for industrial AC drives. The paper considers variable frequency variable voltage operation of a three-phase induction motor in single-phase mode for two common faults of a three-phase inverter, i.e., open base drive and device short-circuit. The motor performance has been extensively analyzed in single-phase mode and remedial strategies have been developed to neutralize large second and other lower order harmonic pulsating torques. In a single-phase open loop volts/Hz control made of a faulty three-phase inverter, it has been demonstrated that odd harmonic voltages at appropriate phase angles can be injected to neutralize the low frequency pulsating torques so as to permit smooth drive operation. It has been shown that the pulsating torque can be further reduced by load dependent flux programming rather than operating with constant rated flux. >
TL;DR: A timed-place Petri net model for flexible manufacturing systems (FMSs) is constructed, which contains two major submodels: the stationary transportation model; and the variable process flow model, and an effective schedule of the part processing can be obtained by using an A/sup based search algorithm.
Abstract: In this paper, a timed-place Petri net (TPPN) model for flexible manufacturing systems (FMSs) is constructed, which contains two major submodels: the stationary transportation model; and the variable process flow model. For multiple automated guided vehicle (AGV) systems, the authors embed a simple rule and introduce a push-AGV strategy in a TPPN model to solve the collision and traffic jam problems of such vehicles. Since a firing sequence of the TPPN from the initial marking to the final marking can be seen as a schedule of the modeled FMS, by using an A/sup */ based search algorithm, namely, the limited-expansion A algorithm, an effective schedule of the part processing can be obtained. To show the promising potential of the proposed work, a prototype FMS is used as a target system for implementation. The experiment results assert that the job-shop scheduling problem can always be satisfactorily solved. >
TL;DR: A speed controller considering the effects of parameter variations and external disturbance for indirect field-oriented induction motor drives is proposed in this paper and an integral plus proportional (IP) controller is quantitatively designed to match the prescribed speed tracking specifications.
Abstract: A speed controller considering the effects of parameter variations and external disturbance for indirect field-oriented induction motor drives is proposed in this paper. First a microprocessor-based indirect field-oriented induction motor drive is implemented and its dynamic model at nominal case is estimated. Based on the estimated model, an integral plus proportional (IP) controller is quantitatively designed to match the prescribed speed tracking specifications. Then a dead-time compensator and a simple robust controller are designed and augmented to reduce the effects of parameter variations and external disturbances. The desired speed tracking control performance of the drive can be preserved under wide operating range, and good speed load regulating performance can also be obtained. Theoretic basis and implementation of the proposed controller are detailedly described. Some simulated and experimental results are provided to demonstrate the effectiveness of the proposed controller. >
TL;DR: Centralized and distributed automated guided vehicle system (AGVS) models for materials handling, and the model for part processing are integrated into a single coherent model that can be used to collectively schedule and control the entire flexible manufacturing system (FMS).
Abstract: Centralized and distributed automated guided vehicle system (AGVS) models for materials handling, and the model for part processing are integrated into a single coherent model. This formulation can be used to collectively schedule and control the entire flexible manufacturing system (FMS) as opposed to the traditional separate scheduling of part processing and material handling. The two AGVS models are based on Petri nets and can be directly used in the scheduling method that uses Petri nets for formulation and heuristic search for solution. This method employs a global search to seek the optimal operation of an entire FMS. Scheduling examples are presented and the method compares favorably with the results simulated using heuristic dispatch rules. >
TL;DR: Two levels of an innovative adaptive switching pattern (ASP) for use in the control of induction machines are described, based on a tolerance band control strategy resulting in nearly sinusoidal stator currents that significantly increases the switching time and reduces the number of double commutations.
Abstract: Two levels of an innovative adaptive switching pattern (ASP) for use in the control of induction machines are described. The ASP is based on a tolerance band control strategy resulting in nearly sinusoidal stator currents. The first level (ASP1) significantly increases the switching time thereby eliminating the very fast switching sometimes experienced. The second level (ASP2) reduces the number of double commutations by one or two orders of magnitude. The price for applying ASP is only a small, irregular, consequential increase in the current error. A rotating reference frame fixed to the rotor flux is applied. This makes ASP especially suitable for application in the field-oriented control of current controlled voltage source inverter (CC-VSI) fed induction motor drives. The theoretical background supported by conclusive simulation results illustrates clearly the significant benefits of ASP over the regular switching pattern often used. To complete the picture a short survey of the various techniques used in the speed control of induction machines is presented in the introduction. >
TL;DR: The state of the art in the control of robotic manipulators in constrained motion tasks is presented, and some early ideas and their later improvements, as well as trends in this field are covered.
Abstract: This paper presents the state of the art in the control of robotic manipulators in constrained motion tasks. Contact control concepts are classified using different criteria, and their main characteristics are analyzed. For each of the presented contact control concepts, the essential characteristics are stated. The paper covers some early ideas and their later improvements, as well as trends in this field. The advantages and drawbacks of the various control schemes are outlined, and they are compared from the standpoint of their implementation issues. In the paper, all characteristic results in the stability analysis of robotic manipulators in the constrained motion tasks are briefly reported. A new approach to the correct solution of contact tasks control is mentioned as well. >
TL;DR: An active power filter for compensating voltage sags that occur on a weak AC power system is described, and a design procedure based on IEEE/ANSI voltage withstand tolerance (IEEE standard 446-1987) is proposed.
Abstract: An active power filter for compensating voltage sags that occur on a weak AC power system is described. The proposed active power filter is especially suitable in situations where sensitive data processing and other critical loads are to be operated on a weak AC system. The proposed filter is fast acting and simple in design. A design procedure based on IEEE/ANSI voltage withstand tolerance (IEEE standard 446-1987) is proposed. Laboratory tests on a prototype filter show fast response and linear correction characteristics. >
TL;DR: The analysis and design of a direct six-switch three-phase PWM rectifier, capable of correcting input unbalance, is presented and results are verified from a 1 kVA breadboard set-up.
Abstract: The analysis and design of a direct six-switch three-phase PWM rectifier, capable of correcting input unbalance, is presented. Based on the input source positive and negative sequence components, an unbalanced transfer matrix in terms of input phase voltages is derived. An online method is used to implement the transfer matrix function and generate the switch gating signals. As compared to other unbalance correction methods, the proposed approach is very simple to implement. It uses only a few discrete analog and digital components. The algorithm of the proposed approach is described in this paper, and results are verified from a 1 kVA breadboard set-up. >
TL;DR: It is suggested that the proposed CS-PPRI is a viable alternative for realizing electronic ballasts for low and high-intensity discharge lamps by having a load independent output current and zero voltage switching (ZVS).
Abstract: A novel topology, current-sourcing push-pull parallel-resonance inverter (CS-PPRI) was investigated theoretically and experimentally. The proposed power stage is built around a current fed push-pull inverter. The main features of the proposed inverter are: a load independent output current and zero voltage switching (ZVS). It is suggested that the proposed CS-PPRI is a viable alternative for realizing electronic ballasts for low and high-intensity discharge lamps. >
TL;DR: Results from an experimental study with a 1 kW hardware laboratory model of the PWM rectifier shows that the dynamic response can be significantly improved even when the DC link capacitor is substantially reduced.
Abstract: The voltage-regulated pulsewidth-modulated (PWM) rectifier is prone to instability. The system can be stabilized by proportional-plus-integral feedback control, but its transient response is slow. This paper describes results of a study of digital control to improve the system dynamic response by pole placement through state feedback. The control algorithm is implemented for real-time operation by using a custom designed system of three high-speed microprocessors. Results from an experimental study with a 1 kW hardware laboratory model of the PWM rectifier shows that the dynamic response can be significantly improved even when the DC link capacitor is substantially reduced. >
TL;DR: An electric motor double-buffered speed measurement method for PC/AT computer application is based on 14.31818 MHz reference clock and covers DC motor speed reversal and an induction motor acceleration.
Abstract: An electric motor double-buffered speed measurement method for PC/AT computer application is based on 14.31818 MHz reference clock. The extremely wide frequency range of 4/spl middot/10/sup 9/ (1.67 mHz to 7 MHz) is independent of sampling time, which can be chosen from 100 /spl mu/s to 4.6 ms. Appropriate software provides real-time graphics presentation of measured speed versus time and storage for further analysis. The enclosed test diagrams cover DC motor speed reversal and an induction motor acceleration. >
TL;DR: A novel means of trajectory planning which incorporates the system's ability to both monitor and control the process is given, and experimental results not only demonstrate highly successful insertion along the desired trajectory, but also demonstrate the ability to detect, recognize, and recover from errors and unwanted situations.
Abstract: A new approach to process modelling, task synthesis, motion control and trajectory planning for robotic assembly is presented. Assembly is modelled as a discrete event dynamic system using Petri nets, incorporating both discrete and continuous aspects of the process. A process monitor based on recognizing contact state transitions is presented. A discrete event controller is developed. The controller issues velocity commands that direct the system toward the next desired contact state, while maintaining currently desired contacts and avoiding unwanted transitions. A novel means of trajectory planning which incorporates the system's ability to both monitor and control the process is given. Experimental results are given for a dual peg-in-the-hole example. The experimental results not only demonstrate highly successful insertion along the desired trajectory, but also demonstrate the ability to detect, recognize, and recover from errors and unwanted situations. >
TL;DR: This paper describes in detail the vision module used by the navigation system and how it is able to monitor continuously its position and to integrate these estimates with the measures provided by the vehicle odometers.
Abstract: This paper is concerned with the problem of determining the position of a mobile vehicle during navigation. In order to achieve this objective a multisensor navigation system for self location of the robot has been developed. By tracking a few known landmarks with a vision module, the system is able to monitor continuously its position and to integrate these estimates with the measures provided by the vehicle odometers. This paper describes in detail the vision module used by the navigation system. >
TL;DR: It is shown how very simple velocity-tracking robust controllers for permanent magnet motors driving nonlinear loads can be designed based on variable structure systems techniques.
Abstract: It is shown how very simple velocity-tracking robust controllers for permanent magnet motors driving nonlinear loads can be designed based on variable structure systems techniques. Very fast dynamics, accurate and robust velocity-tracking are achieved with very simple hardware components without resorting to powerful digital signal processors and related interface hardware. A cascade control structure is used to ensure maximum flexibility. The controller for a DC motor is considered in great detail. Extension to AC synchronous PM motors is also presented. At the different control levels robustness is addressed with specific algorithms and the simplest solution is always selected. The controller architecture for both DC and AC synchronous motor are presented and discussed in the paper. Experimental results related to the control of a DC motor driving a nonlinear load are also shown. They demonstrate feasibility and excellent performances of the proposed approach. >