Digital Microcomputer Research Articles

Digital Computer Simulation of Induction Machines.(Dept.E)

A digital simulation of an induction machine is described. The simulation is suitable for analyzing the operation for either a motor or generator with different speeds. The induction generator load is represented in the simulation by symmetrical or unsymmetrical R, L circuits. The computer program described in this paper calculates both the transient and steady-state performance of the machine from its equivalent circuit parameters. The effect of the magnitude and direction of the generator shaft speed on its stability is dis cussed. The method of simulation is relatively easy to program and can be solved with a personal digital computer. The example given was applied to study and illustrates the performance of the induction generator under different operating conditions.

Kalman Filtering Solution Converges on a Personal Computer

Instantaneous observability is used to watch a system output with very fast signals as well as it is a system property that enables to estimate system internal states. This property depends on the pair of discrete matrices [Formula: see text] and it considers that the system state equations are known. The problem is that the system states are inside and they are not always accessible directly. A process, which is a time-varying running program in four parts composes the system under investigation here. It is shown it is possible to apply Kalman filtering on a digital personal computer’s system with particularly the four parts like the ones under investigation. A computing process is performed during a period of time called latency. The calculation of latency considers it as a random variable with Gaussian distribution. The potential application of the results attained is the forecasting of data traffic-jam on a digital personal computer, which has very fast signals inside. In a broader perspective, this method to calculate latency can be applied on other digital personal computer processes such as processes on random access memory. It is also possible to apply this method on local area networks and mainframes.

Anti-Jamming Modification of Exciting System in 600MW Generating Unit

In order to reduce excitation system swing and resultant reactive power swing, namely, reduce external electromagnetic interference to stable operation of 600MW generating unit, the paper analyses unit excitation control mode and designs hardware and software of excitation system. First, digital microcomputer control system organization was designed based on nonlinear control theory, which had an increase of control mode such as PID control mode, nonlinear optimum electronic control (NOEC) mode besides original voltage difference and current control mode. Second, full duplex collocation configuration mode of excitation system was designed, namely two controllers were master-slave concurrent, and each controller could meet excitation requirement of various operation condition including constrained excitation. Finally, in electric network disturbance test, measured excitation system parameters recovered stably in 1020 ms such as stator voltage Ut, rotor voltage Uf, comprehensive amplified control voltage Uc, active power P and reactive power Q. It is verified that transient stability and unit operating condition are improved.

A remote terminal unit multimedia.

One of the problems of remote terminal unit multimedia (RTUM) for the acquisition and data control in real time is the time it takes a process in carrying out calculations for one or more critical variables inside a supervision and control system. The system response to any change in these variables depends on this time delay. An RTUM is a computer system connected to a net thought to supervise and to control, in an automatic way, some of the electronic devices that exist in a multimedia recording studio. In order to reduce the inherent latency in the data capture, we have designed an RTUM with ASIC FPGA digital devices, whose functions written in VHDL are of specific purpose. Each device contains in its hardware a specialized function which is carried out in a parallel way inside a single clock cycle. In this paper we presented the description of the design of a remote terminal unit based in a digital microcomputer whose peripheral are ASIC FPGA standard devices, which are controlled by means of a general purpose microprocessor. The result is a control and acquisition multimedia data RTUM system with a smaller response time due to the parallel processing.

Hierarchical digital systems modeling utilizing hardware description languages for computer engineering education

This paper describes a hierarchical modeling approach and teaching methodology for digital microcomputer system modeling including abstract event modeling, mixed-mode event and timing-based, and gate level modeling. A structured instructional approach to fundamentals of computer design and simulation is given based on the Verilog hardware description language (HDL). Example models are given for common digital system components which illustrate the hierarchical learning model presented. Example simulation methods, various simulation hierarchies, and graphical simulation output are presented for the Verilog models discussed. Aspects of the simulation hierarchy are given with respect to system complexity, and simulation complexity for implementation and testing. Finally, educational aspects and merits, with emphasis on student perception and evaluation, of this language as a design tool are presented.

On-line particle-image velocimeter: an integrated approach

We describe an on-line particle-image velocimeter (PIV) and its implementation for the measurement of the velocity field in steady and unsteady flows. The instrument uses up-to-date solid-state sensors, dedicated electronic boards, and digital microcomputers to combine the image-acquisition and processing steps into a single, fully integrated unit. A calibration experiment evaluates the accuracy of the velocity measurement instrument. The experiment consists of the measurement of the velocity distribution of a laminar wall jet and shows that the velocity, as well as the vorticity profiles, obtained by using the on-line PIV compare well with those obtained by means of a conventional photographic PIV and a numerical prediction.

Automated site characterization for robotic sample acquisition systems

A mobile, semiautonomous vehicle with multiple sensors and on-board intelligence is proposed for performing preliminary scientific investigations on extraterrestrial bodies prior to human exploration. Two technologies, a hybrid optical-digital computer system based on optical correlator technology and an image and instrument data analysis system, provide complementary capabilities that might be part of an instrument package for an intelligent robotic vehicle. The hybrid digital-optical vision system could perform real-time image classification tasks using an optical correlator with programmable matched filters under control of a digital microcomputer. The data analysis system would analyze visible and multiband imagery to extract mineral composition and textural information for geologic characterization. Together these technologies would support the site characterization needs of a robotic vehicle for both navigational and scientific purposes.

Time‐Delay Compensation in Active Damping of Stuctures

With the higher modes being considered in structural vibration control, practical problems such as the effect of the time delay between sensing the structural motion and applying the control force become more pronounced. Instability due to time delay is observed experimentally using a carefully calibrated model of a typical single‐span bridge modeled as a continuous system. The control action is applied using an accelerometer, analog integrator, cable, post, and hydraulic actuator in conjunction with an on‐line digital microcomputer. A practical scheme for time‐delay compensation based on response sampling, curve fitting, and extrapolation is employed. The purposed scheme has the advantage of eliminating the observation spillover that may cause instability in the control system on one hand, and may serve as an almost perfect state estimator on the other hand. The correlation between the analytical and experimental results is presented.

A microprocessor-regulated constant voltage, current, wattage, and temperature electrophoresis power supply

The analog control circuitry typically found in commercial electrophoresis power supplies was replaced by a digital microcomputer. Analog to digital converters were used to monitor the voltage applied to and current passed through an electrophoresis cell. Microcomputer programming was employed to compare converter input values with preselected operating parameters and then calculate a required output voltage. Timing sequences were generated through programming utilizing clocks located on the interface boards. A digital to analog converter was employed to apply a control voltage to a constant voltage power supply. This process was completed at least 20 times each second. BASIC programming subroutines were written to maintain constant voltage, current, power (wattage), and temperature. To these operating procedures, other techniques such as automated endpoint detection of isoelectric focusing and pulsed waveform outputs were easily added. This power supply containing a microcomputer system as the feedback element was shown to have a greater stability and versatility than conventional supplies.

Forecasting compensatory control (FCC) of machining flatness

Forecasting Compensatory Control (FCC) was implemented to improve the flatness of three dimensional prismatic workpieces in an end-milling operation. The basic logic of the strategy is based on inprocess error measurement, stochastic modelling, and prediction and compensation of the cutting errors. The proposed FCC system consisted of a newly developed laser-based in-process flatness error measurement system, a hydraulic positioning servo system, and a digital microcomputer control system. Through the application of the FCC system to on-line cutting experiments, the workpiece flatness error was reduced by up to 80% during machining.

In-Process Control of Cylindricity in Boring Operations

This paper presents a new on-line control scheme utilizing the Forecasting Compensatory Control (FCC) method for improving cylindricity in boring operations. The proposed control method was implemented through the development of a laser-based in-process cylindricity measurement, a digital microcomputer, and a piezoelectric actuator system. Through on-line cutting experiments, the improvement in cylindricity accuracy was found to be in excess of 60 percent.

Microcomputers In The Forensic Engineering Office

Microcomputers, or personal computers, were virtually unknown a decade ago. Today they are relatively inexpensive and widely found in schools, banks, offices, industries and homes. This paper deals with the application of general purpose digital microcomputers in the forensic engineering office. The objective of the presentation is to share some ideas about ways in which the author is using microcomputers in his forensic engineering practice. In doing so, there is no intent to promote any particular brand of microcomputer or microcomputer software but is solely for the purpose of sharing ideas that may help other forensic engineers become more efficient and productive in their work. Microcomputer systems possess certain characteristics that make them highly desirable tools. They are extremely fast, accurate, capable of remembering thousands of items of information at a time, versatile, flexible, and ideal at performing repetitive types of operations. The author has been using co

Digital's personal computers

Digital Equipment Corporation's three series of personal computers have been designed to meet different types of application needs of business and technical users. Common ergonomic concepts were applied in designing two sizes of system units, the keyboard, and CRT monitors used with all three series. The hard-ware architecture of each series was established to attain its specific operating and performance goals at acceptable cost and unit size. Making use of the computers' inherent expandability, there have been major hardware upgrades--in memory, mass storage, and graphics capability in particular--since their introduction. Software upgrades have included implementation of additional industry-standard operating systems with modifications for optimum performance.

Digital time-constant regulator for micromachines

Abstract A digital microcomputer based method of changing the time constants of the field and damper windings of a micromachine is described. The need for shadow windings to generate the necessary feedback signals, as used in earlier analogue methods, is eliminated.

Dielectric spectroscopy at sub-audio frequencies—two techniques in comparison

Two dielectric spectrometers for use at sub-audio frequencies have been designed around a digital microcomputer and data acquisition system. In one technique the driving signal and the current response are harmonic. In the other technique a current transient results from a voltage step. Comparison of the two techniques on real materials reveals good agreement between complex relative permittivity spectra. Moisture and electrode polarization aspects of specimen preparation are addressed.

Automotive Electronics: Computerized Engine Control

The advantages of using electronics to control the engine combustion, are discussed, the electronic spark timing control is described, the efforts by Chrysler, General Motors and Ford and reviewed, and the closed loop feedback control system is described. An electronic spark timing control which is part of Chrysler's Lean Burn system, senses 8 variables before computing the time for spark firing. The variables sensed include amibent air temperature, engine coolant temperature, manifold vacuum, engine speed, throttle position, and rate of change of the throttle position. Speculation has, however, centered on the progressively increasing sophistication of the microprocessor which offers the flexibility of being able to rapidly alter the control system to respond to additional variables or to control additional functions simply by changing the program. A digital microcomputer (MISAR) which controls spark timing is described; it comprises a microprocessor and table of 350 data points. Test runs indicate that MISAR achieves a 9% improvement in fuel economy. Efforts to produce an electronically controlled carburator for closed loop fuel metering, and efforts to demonstrate that electronic engine controls can help meet fuel and emission standards in low-volume applications are briefly discussed.

A Nuclear Reactor DDC Using a Microcomputer

This paper describes the implementation objectives, methods, results and problems behind an experiment to control a one megawatt pool reactor with a digital microcomputer. The Direct Digital Controller (DDC) was built to investigate the uses and advantages of microcomputer systems in process control applications. New features include: operator oriented displays, dynamic feedforward control for improved transient performance, system safety checks, online self-diagnostics and maintenance aids.