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Electrical Engineers - Part IIA: Automatic Regulators and Servo Mechanisms, Journal of the Institution of

Issue 2 • Date May 1947

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Displaying Results 1 - 17 of 17
  • Elements of position control

    Publication Year: 1947 , Page(s): 161 - 176
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2529 KB)  

    The paper offers a general descriptive survey of position control, including the characteristics of the usual input signal and load and their effects on performance. The basic principles of automatic control are applied to unmonitored and monitored position-control systems. Displacement-displacement servo systems are dealt with in some detail, the emphasis being on electric-non-thermionic amplifiers, and electric servo motors. The performance of these systems is discussed without any analysis, but the results of analysis are used for the recommended performance. View full abstract»

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  • The use of servos in the Army during the past war

    Publication Year: 1947 , Page(s): 177 - 189
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    The paper reviews the principal applications of servo mechanisms to Army weapons during the past war, giving in each case a general description of the particular system employed, and outlining the main historical and design factors governing its adoption. Features of design of special interest are noted. It is not claimed that the number of examples given is exhaustive, but it is representative of the field covered in relation to Army weapons. View full abstract»

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  • The nature of the operator's response in manual control, and its implications for controller design

    Publication Year: 1947 , Page(s): 190 - 206
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1827 KB)  

    This paper gives a brief account of a series of measurements of the movement of the controller handle and of the error of aim under conditions simulating the laying of a gun on a moving target by manually-controlled power operation. The results are analysed with the object of obtaining the ¿ operator's response, ¿ i.e. the relationship between the movement made by the operator's hand and the error and its variations as seen by the eye. It is found that the response relationship is non-linear, but the relationship may to a useful extent be approximated by a ¿ nearest linear law, ¿ namely that the speed of handle movement is dependent upon both the error and the rate of change of error, subject to a time delay which corresponds to that known to be involved in nerve transmission. The actual movement is found to differ from this relationship, both in being intermittent or jerky and also in being subject to apparently haphazard variations. A project for further investigation is outlined by which the difficulties in more detailed analysis may be overcome. On the basis of the results so far obtained it is shown that an explanation is provided for some of the outstanding phenomena observed in the laying of guns and in other cases of manual control of power-driven apparatus, and it is shown that there is an upper limit to the accuracy of control obtainable. Finally, the paper shows how the error incurred in tracking a target is fundamentally related to and depends upon the time delay which occurs between the stimulus received by the eye and the resulting muscular response, and gives comparative values for the theoretical limit of accuracy obtainable with controllers having various types of response characteristics, as a function of this delay time, for an otherwise ideal operation. The lines along which an improvement of performance may be sought are discussed in the light of these limits and the other phenomena observed. View full abstract»

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  • Discussion on ¿Applications in the military sphere¿ at the Convention on Automatic Regulators and Servo Mechanisms, 20th May, 1947

    Publication Year: 1947 , Page(s): 203 - 206
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  • The authors' replies to the discussion on ¿Applications in the military sphere¿

    Publication Year: 1947 , Page(s): 206 - 207
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  • Some servo mechanisms used by the Royal Navy

    Publication Year: 1947 , Page(s): 208 - 221
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    In naval gunnery, especially in anti-aircraft systems, it is necessary 1br the gun to be kept continuously laid upon the target, regardless of the ships movements, with a high degree of accuracy. The paper discusses the implications of this requirement in terms of the angular movements to be imparted to a normal 2-axis gun, and shows the necessity for complete automatic power operation of the gun from the calculating position. It also shows that automatic operation is likewise necessary in every link of the complex system that constitutes a modern fire-control arrangement. From this introduction the paper describes the history of early efforts at automatic control, leading up to methods used in H.M. Ships during the war. The relative merits of electricity and hydraulics for these large position-control servos are discussed, and the difficulties of adapting the earlier designs of mountings for automatic control are presented. The paper ends with a summary of the somewhat stringent requirements which naval servos must satisfy. View full abstract»

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  • Data-transmission systems

    Publication Year: 1947 , Page(s): 222 - 235
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    The paper deals with the methods employed for the transmission of data which have been used in the Fighting Services up to the present day. An historical review is made of the main types of instruments used over the last 40 years, particularly for Naval purposes. The development of the present types of data transmission¿in particular the magslip¿is dealt with more fully, and references are made to parallel developments in this and other countries. Various applications are described, giving the methods of application and limitations of use of the various types of element. A number of photographs showing typical magslip elements are included, and an abbreviated list of types of magslips and some performance figures are given in an Appendix. View full abstract»

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  • Naval applications of electrical remote-positional controllers

    Publication Year: 1947 , Page(s): 236 - 254
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    A survey is made in this paper of some of the applications in the Royal Navy of all-electric servo mechanisms for armament control purposes. The need for the greatest possible measure of automatic operation in fire-control prediction, and in the pointing of the guns in accordance with this prediction, in order to combat high-speed aircraft and to make the fullest possible use of the continuously up-to-date location of the target by radar, led to the introduction of the servo and remote power-control systems described. By far the greater part of the systems referred to in the paper are therefore the results of development and application to specific projects over the past ten years. Brief reference is, however, made in the first part of the paper to some earlier forms of servo mechanisms of the contact-operated type used in the Navy, since this is of interest as a background to the later and more modern types of continuously operating servos, which have largely superseded them. This is followed by a description of some applications of highperformance servos of small or medium powers. These are mostly of the type using a split-field d.c. motor in which the armature of the motor is supplied direct from the d.c. supply through a series resistance (to limit the current at standstill) and the motor fields from a thermionic amplifier under the control of the servo transmission. Finally a description is given of remote power-control applications of large power in which the initial amplification is by thermionic amplifier, but in which further power amplification is obtained from rotating machines (Metadyne and Ward-Leonard) feeding the armatures of separately excited d.c. motors which drive the load. A general reference only has been made to the M-type and magslip electrical data-transmission systems used for the servos and remote power-control schemes described, since information concerning them is given in the paper on ?Data-Transmission Systems? by Mr. J. Bell. View full abstract»

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  • Discussion on ¿Some naval applications¿ at the Convention on Automatic Regulators and Servo Mechanisms, 20th May, 1947

    Publication Year: 1947 , Page(s): 251 - 254
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  • The authors' replies to the discussion on ¿Some naval applications¿

    Publication Year: 1947 , Page(s): 254 - 255
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  • The use of servo mechanisms in aircraft

    Publication Year: 1947 , Page(s): 256 - 265
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1763 KB)  

    In each field in which servo mechanisms have been applied in aircraft, different designers have used different mechanisms to achieve the same result, and each particular type of mechanism has been used for different applications. Therefore, this survey can show no more than a few cross-sections. Section 1 gives a brief account of the conditions which a servo system will encounter in the air; Section 2 is an account of typical applications to which servo systems are put in the air; and Section 3 is an account of some trends in development, as illustrated by a few designs which have been used. View full abstract»

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  • Discussion on ¿The aeronautical aspect¿ at the Convention on Automatic Regulators and Servo Mechanisms, 21st May, 1947

    Publication Year: 1947 , Page(s): 266 - 268
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  • The author's reply to the discussion on ¿The aeronautical aspect¿

    Publication Year: 1947 , Page(s): 268 - 269
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  • Hydraulic remote position-controllers

    Publication Year: 1947 , Page(s): 270 - 282
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1622 KB)  

    Brief descriptions arc given of the significant characteristics of the more important hydraulic devices used in remote position-controllers. Such devices include valves, dashpots, pumps, approximately constantpressure sources and hydraulic motors. Combinations of these primary devices are then described which, for analytical purposes, may be regarded as single ¿elements¿ in the control sequence of any servo-mechanism of which they form a part. Amongst these combinations are pump- and valve-controlled power drives, various types of hydraulic relays and passive mechanical networks incorporating dashpots. The practical applications of these hydraulic servoelements are then illustrated by means of mathematical analyses in which are deduced the conditions for stability and performance to be expected of typical hydraulic remote position-control systems. View full abstract»

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  • Electrical remote position-indicating systems as applied to aircraft

    Publication Year: 1947 , Page(s): 283 - 291
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    Electrical remote position-indicating systems are usefully and extensively applied to modern aircraft. To meet rigorous aircraft requirements, existing systems, as applied to other branches of engineering, have been developed and new systems devised. Existing literature on the subject as a whole is dispersed; the paper therefore serves to collate the existing information. The principles of operation, characteristics and applications of the various systems used on British. American and German aircraft are described, and an endeavour is made to illustrate their advantages and limitations for different applications. View full abstract»

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  • Methods of testing small servo mechanisms and data-transmission systems

    Publication Year: 1947 , Page(s): 292 - 297
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    The testing of small servo mechanisms and data-transmission systems requires the design of equipment for applying input signals of varying types and for measuring the resulting response at the output shaft. The mechanisms to be tested were all of a type in which a relatively small power was available, and the testing equipment described was specially designed to ensure observations of great accuracy, i.e. within about 2 min of arc, and to require a negligible amount of power to operate it. Direct methods of measuring response by a pen or pointer on a revolving drum were impracticable, and the basis of the equipment was the use of mirrors and light beams. Equipments are described for applying step-function signals (which represent sudden movements of the input shaft over various angles) both to servo mechanisms and data-transmission apparatus, and also for the accurate measurement of the response. A description is given of a harmonic generator which can be used to apply signals of accurate sine-wave shape, varying in amplitude from 1° to 80° and with frequencies from 0.15 to 20 c/s Methods of determining the maximum amplitude of the harmonic response and the phase lag are described. The results of tests on (a) a range-conversion servo mechanism, (b) a 2-in Magslip receiver driven by a 3-in Magslip transmitter, (c) a 3-in synchro repeater driven by a Magslip transmitter, and (d) a German 500-c/s data-transmission system are given. A special brake, designed to enable the operation of a small servo mechanism under load to be studied, is described. Methods of observing the error in response with continuous rotation of the transmitter shaft owing to irregularities of construction are given, and also methods of estimating the average error in response owing to steps of different type and amplitude. View full abstract»

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  • Some characteristics of a human operator

    Publication Year: 1947 , Page(s): 298 - 304
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1198 KB)  

    The paper discusses experimental findings which aid an understanding of the basic limitations of a human operator as an element in a servo system. It is shown how experiments on threshold effects can guide the choice of both display magnification and gear ratio. At least 2 sec appears to be required to develop the maximum perceptual acuity, but a time greater than this is usually needed in accurately setting a control for full confidence in accuracy to develop. The mechanisms of muscular movements are discussed. Reciprocatingrnovements can be performed at higher rates than circular movements, although the latter are less fatiguing. Measurements of the mechanical efficiency of man may be worth applying under conditions of heavy work. The conditions of tracking are shown to resemble multiple-choice reaction-time experiments, with a lag between stimulus and response that is strictly indeterminable, but which is generally of the order of 0.3 sec. Discontinuity in the operator is demonstrated by the inability to halt a reacting movement within 0.2 sec of its start. In practical design, the advantages are stressed of incorporating the maximum possible display magnification; of abolishing any striction in the control, possibly by using two hands; of using high rates of turning; and of introducing as much inertia as the operator can manage. The paper concludes with a note on the acquisition of skill in tracking, particularly stressing the need for simple training aids which isolate the individual stimulus-response elements, and which allow accurate scoring and control of difficulty in the task facing the operator. View full abstract»

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Aims & Scope

The Journal of the Institution of Electrical Engineers - Part IIA: Automatic Regulators and Servo Mechanisms was published by the IET in 1947.

Full Aims & Scope