Microprocessor Implementation Research Articles

Improved direct digital control algorithm for microprocessor implementation

An improved optimal regulator control system synthesis method has been developed in order to obtain good steady-state characteristics for the designed control system in spite of variations of the parameters of the controlled object. This control system includes proportional action, averaged derivative action, and integral action. Several physical constraints, such as input variable constraints, state variable constraints, and input delay times, are treated simultaneously. To reveal the effectiveness of the method, the speed control system of a static Scherbius induction motor system was synthesized by this method and satisfactory experimental results were obtained using microprocessor system as the controller. In this experiment, the processing time in the microprocessor must be considered as an input delay time; and the input variable constraints due to the restricted range of the controlling angle of the cycloconverter must be taken into account.

Theoretical Developments in Discrete-Time Control

Significant theoretical developments in discrete-time control over the past 10-15 years are reviewed. Topics reviewed include optimal-control, Riccati equations, controllability, stability, robustness, deadbeat control, minimum-time systems, sampling, quantization, microprocessor implementation, and stochastic systems. Emphasis is placed on topics that are peculiar to discrete-time systems and do not generalize from continuous-time theory.

Design of Digital Filter Suitable for Microprocessor Implementation

A technique of designing a digital filter suitable for microprocessor implementation is presented in this paper. A transfer function is approximated from a given specification, whose coefficients are expressed as simple combinations of two's power. Then, the signal can be processed with high speed by using only addition and shift operators instead of multipliers.Two sets of pole and zero locations are first obtained by means of ordinary design methods, which correspond to upper and lower bounds of a given specification. Then, the desired transfer function is derived, whose poles and zeros locate near the center of these two sets obtained earlier. Some spectral transformations are introduced to shift the pole and zero locations to the suitable places.The design examples for Butterworth, Chebyshev, inverse Chebyshev, and elliptic approximations are included, and their processing times are compared with those using multipliers by using 8-bit and 16-bit microprocessors.

Optimal operation of integrated processing systems. Part I: Open‐loop on‐line optimizing control

AbstractA new algorithm for the continuous tracking of the optimal economic operating conditions of an integrated chemical plant has been developed. The method does not make use of fundamental models of the plant but is based on an on‐line search using experimental moves of the independent variables. The results of these moves provide the data for the identification of a dynamic process model. This model allows one to determine the gradient of the objective function and thus guides the next move of the independent variable eventually leading to the optimum. The advantages of the new technique over other methods are demonstrated in simulation examples: The speed of tracking is equally fast or faster than the relaxation speed of the system after a step change. The noise insensitivity allows safe tracking of the optimum despite significant measurement errors. As a key feature a decentralized form of the algorithm is developed making it suitable for distributed microprocessor implementation.

Parallel and cascade microprocessor implementations for digital signal processing

Microprocessors have achieved great popularity because they are inexpensive, convenient, and flexible. A microprocessor with an architecture chosen to efficiently perform digital signal processing algorithms would retain these advantages when used to implement digital signal processing. One such architecture is the Research Signal Processor (RSP), which was designed by A. Peled to gain these advantages. In order for such a microprocessor to be a cost effective signal processing solution, however, it is necessary that it be capable of implementing a wide range of digital signal processing applications, so that the cost of developing an economical LSI version can be borne by many applications. In addition to efficiently implementing single microprocessor applications, then, it is also important to have the capability of connecting into systems that can efficiently implement large applications. In this paper, it is demonstrated that many digital signal processing tasks can be decomposed into subtasks that permit simple parallel and cascade multiple microprocessor implementations. In some cases, several implementations of the same and competing algorithms will be presented and contrasted. The I/O functions required to support these structures are discussed, and the RSP I/O capability which was chosen to meet these requirements is described. The effect of the microprocessor I/O capability on the total system cost will also be discussed.

Microprocessor Controller for a Thyristor Converter with an Improved Power Factor

A microprocessor-based algorithm for steady-state and dynamic control of a modified six-pulse converter with two neutral-connected auxiliary thyristors is described. The algorithm which is applicable to the standard six-thyristor bridge is experimentally verified and is found to give a very fast, precise, and equidistant control of the thyristor triggerings. This paper describes the operation of the modified bridge, the control algorithm and the microprocessor implementation, and gives the bridge transfer function and dynamic response.

Adaptive, high precision, satellite attitude control for microprocessor implementation

A control system is presented for three-axis, gas jet, satellite attitude control having application to any spacecraft where precise pointing is required within stringent mass and power limitations. Several novel features are incorporated as follows: parabolic switching boundaries are employed with parameters which adapt to a disturbing acceleration estimate in order to achieve a zero offset steady-state limit cycle of preset amplitude in the arcsecond region which minimizes both fuel consumption and thruster operation frequency. The disturbing acceleration estimate is obtained from a third-order state estimator, together with angle error and rate estimates using an angle error measurement from a rate integrating gyro and a jet drive input. Time optimal recovery from large initial angle errors and rapid response to step changes in disturbing acceleration are achieved. In addition, stable control is obtained with disturbing acceleration approaching the control jet acceleration. A slew control algorithm is incorporated which enables the same control law to be utilized for fuel optimal slewing through unlimited angles, one axis at a time. Simulation results are presented, including demonstration of stochastic performance with gyro and jet noise.

Application of improved optimal regulator technique to power electronics

AbstractA control system synthesis method for a multi‐input and multi‐output system with input dead time, input variable constraints, and state variable inequality constraints is described. A practical control algorithm which is suitable for microprocessor implementation is derived from the method and is applied to an induction motor control problem. Good simulation results are obtained, although the designed control system is suboptimal. The control system configuration designed by this method is explained clearly. It is proved that integral actions as well as proportional actions are introduced so as to guarantee good steady‐state characteristics in spite of parameter variations of the controlled object. Moreover, a kind of derivative action is introduced to compensate for input dead time effects.

Self-tuning optimum start control of heating plant

The problem of controlling the start-up of heating plant in industrial and domestic buildings is considered and the need for a self-tuning start control scheme is explained. Using a simple semi-empirically derived relationship between the time required to preheat the building before occupancy and the measured temperatures, a self-tuning start controller is developed based on an on-line adaptive predictor. The controller assumes no prior knowledge of the thermal characteristics of the heating plant and building, and is suitable for low-cost microprocessor implementation. Results obtained from a hybrid simulation of a heating plant, building and environment show that the self-tuning controller behaves well and has superior performance characteristics compared to conventional start controllers. The results of preliminary experimental tests, using a microprocessor-based controller, suggest that, in certain circumstances, further simplifications to the control algorithms can be made so that implementation on small single-chip microcomputer systems, which are suitable for the control of domestic heating equipment, is feasible.

Optimal design of PID regulators

Tuning of three-term controllers, a widely popular device for process control, has always been accomplished by semi-empirical rules. The aim of this paper is to establish a link between PID regulators and optimal feedback design for linear systems. After showing how the optimal control theory can be tailored to the design of optimal regulators, the results are extended to the discrete-time case and the feasibility of a microprocessor implementation is assessed with the aid of benchmark tests

Microprocessor implementation of the Kalman filter: M. Page Microelectron. J., 10, (3) 16 (1969)

Microprocessor implementation of the Kalman filter: M. Page Microelectron. J., 10, (3) 16 (1969)

Speed-optimised microprocessor implementation of a digital filter

A practical, efficient scheme is described for the implementation of a real-time programmable digital filter using a microprocessor. The use of distributed arithmetic is known to be able to provide increased speeds by avoiding time-consuming multiplications. To achieve maximum speeds, the working program in a microprocessor implementation should, as far as possible, contain only those instructions which perform the arithmetic functions. High component efficiency is also achieved if the inherent control capabilities of the microprocessor are fully utilised, in particular where support hardware elements are used. Simple techniques are proposed for meeting the above objectives, which are inexpensive to implement and are readily adaptable for most standard microprocessors. The low cost and enhanced speed of implementation makes it attractive as an economical alternative to hard-wired digital filters for working frequencies in the audio and telephony range of frequencies and as a building block for cascade realisation of larger length filters, particularly of the FIR type. Some results of an experimental model using the commercial standard 8080A micropressor are given and comparisons with implementations for other micropressors are made.

Inherent error correction in analogue CCD adaptive filters

There are many sources of imperfection in an analogue charge-coupled device CCD programmable transversal filter (PTF) which cause problems; namely, varying signal and reference channel gains, charge-transfer inefficiency in the CCD and multiplier errors. This paper shows how these error sources may be automatically compensated for in an adaptive filter based on a CCD programmable filter. The adaptive filter is based on a form of the Widrow LMS algorithm, which is both simple and well suited to microprocessor implementation, particularly where that is the means of implementing the PTF reference waveform.

Self-tuning charge control scheme for domestic stored-energy heating systems

The paper examines the problem of controlling domestic electric stored-energy heating systems and describes the development of a self-tuning control scheme which can adjust the off-peak charging of the store to minimise electrical energy consumption. The charging time is controlled by a store temperature-regulator which is designed by application of the well known self-tuning minimum-variance control technique. The regulator uses a statistical estimator, based on a lumped-parameter model of the thermal behaviour of the building and heating system, to predict the next day's heating energy demand before the start of the off-peak charging period. The control scheme assumes no prior knowledge of the thermal characteristics of the building or heating plant and is suitable for low-cost microprocessor implementation. The long-term performance of the self-tuning charge controller is assessed by digital simulation of a building heated by one of two widely different types of commercial storage heating systems (a fan-assisted block storage heater and a water-storage central heating system). Results are presented which show that the control scheme behaves well and achieves substantial energy savings without the need for manual commissioning. Modification of the basic self-tuning control scheme to compensate for the peculiarities observed in the operation of high-leakage or low-capacity stores is also investigated.

A signal processing compiler for the simulation of digital networks

The time-domain analysis of an arbitrary digital network can be efficiently achieved by the generation of a simulation code describing the calculations involved in the network and by interpreting this code for successive time indexes. The simulation code is also a useful tool for the microprocessor implementation of the network.

Design of recursive digital filters for microprocessor implementation, using fixed-point arithmetic

A digital filter structure which is suitable for program execution and fixed-point arithmetic is presented. Implementation of digital filters based on Laplace domain design using the bilinear transform is discussed; then some alternative techniques for designing the coefficient values are proposed.

Microprocessor implementation for bandwidth compression of continuous tone facsimile picture and a proposal of differential plane coding

AbstractThe research on applying the flexibility of a microprocessor into facsimile has been progressing. In general, it has been considered difficult to realize encoding and decoding processes by a general‐purpose one‐chip microprocessor due to the limitation of its processing capability. However, it is desirable to use flexible software processing for efficient encoding of a tone image or a mixed image between a tone image and characters. In this paper, we show a qualitative limit of an image decoding process by software using a one‐chip microprocessor based on experimental investigation. In addition, we propose differential Plane Coding which is an implementable coding system within this limitation. Especially, it has been proved that an efficient encoding of a mixed image is possible by changing the encoding system in the first differential plane depending on the nature of the image.

The canonical signed digit code structure for FIR filters

This correspondence introduces a new computational structure for FIR filters that combines the advantages of canonical signed digit code (CSC) with the efficiency of the partial sum organization. An example shows how microcode for a microprocessor implementation may be developed directly from the filter coefficients.

Fatigue damage monitoring

The instrument described is a battery operated fatigue damage indicator, designed for continuous field use, attached permanently to the structure being monitored. It is unique in its use of a CMOS microprocessor and continuous LCD display and uses a new algorithm which is a reformulation of an existing fatigue analysis technique so as to render it more suitable for microprocessor implementation. It is anticipated that the instrument could find wide application in the construction, maintenance and aviation fields and the oil industry.

Microprocessor Control of Position or Speed of an SCR DC Motor Drive

In silicon-controlled rectifier (SCR) dc motor drive control, it is desirable for a microprocessor to perform both the control law computations and the logical functions of SCR firing. However, because of their limited real-time capabilities, present-day microprocessors cannot accommodate excessively lengthy control algorithms. This paper presents a method, suitable for microprocessor implementation, of controlling the position or speed of an SCR dc motor drive which uses a half-wave single-phase supply. The state-space equations of the system are first obtained. The derivation of a simple control law is given next, followed by the stability and error analysis of the controller. Finally, it is shown from simulation experiments that the scheme is effective in controlling a 3-hp dc motor.