1、raising standards worldwide NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW BSI Standards Publication BS ISO 8625-4:2011 Aerospace Fluid systems Vocabulary Part 4: General terms and definitions relating to control/actuation systemsBS ISO 8625-4:2011 BRITISH STANDARD National f
2、oreword This British Standard is the UK implementation of ISO 8625-4:2011. The UK participation in its preparation was entrusted to Technical Committee ACE/69, Aerospace hydraulic systems, fluids and components. A list of organizations represented on this committee can be obtained on request to its
3、secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 69625 1 ICS 01.040.49; 49.080 Compliance with a British Standard cannot confer immunity from legal obligations. This British
4、Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2011. Amendments issued since publication Date Text affectedBS ISO 8625-4:2011Reference number ISO 8625-4:2011(E) ISO 2011INTERNATIONAL STANDARD ISO 8625-4 First edition 2011-10-15 Aerospace Fluid
5、 systems Vocabulary Part 4: General terms and definitions relating to control/actuation systems Aronautique et espace Systmes de fluides Vocabulaire Partie 4: Termes et dfinitions gnraux relatifs aux systmes de commande/dactionnement BS ISO 8625-4:2011 ISO 8625-4:2011(E) COPYRIGHT PROTECTED DOCUMENT
6、 ISO 2011 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in
7、the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedBS ISO 8625-4:2011 ISO 8625-4:2011(E) ISO 2011 All rights reserved iiiCont
8、ents Page Foreword iv Introduction . v Scope . 1 Terms and definitions 1 4.1 Control system classification 1 4.2 Control system technology (control engineering) . 3 4.3 Control system performance (servomechanism) 9 BS ISO 8625-4:2011 ISO 8625-4:2011(E) iv ISO 2011 All rights reservedForeword ISO (th
9、e International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committ
10、ee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechn
11、ical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member
12、bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying
13、any or all such patent rights. ISO 8625-4 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 10, Aerospace fluid systems and components. ISO 8625 consists of the following parts, under the general title Aerospace Fluid systems Vocabulary: Part 1: General term
14、s and definitions relating to pressure Part 2: General terms and definitions relating to flow Part 3: General terms and definitions relating to temperature Part 4: General terms and definitions relating to control/actuation systems BS ISO 8625-4:2011 ISO 8625-4:2011(E) ISO 2011 All rights reserved v
15、Introduction ISO 8625 contains only those terms which can be applied to general equipment and systems. Terms which are only used for specific applications and specific components are to be incorporated into the relevant product specifications and product standards. Terms and definitions for componen
16、ts and systems which are associated with other systems (such as electromechanical actuation systems or electronic control units) are incorporated only on a very general basis, provided they have direct interfaces with fluid systems. BS ISO 8625-4:2011BS ISO 8625-4:2011 INTERNATIONAL STANDARD ISO 862
17、5-4:2011(E) ISO 2011 All rights reserved 1Aerospace Fluid systems Vocabulary Part 4: General terms and definitions relating to control/actuation systems Scope This part of ISO 8625 defines general terms relating to control/actuation systems in the field of aerospace fluid systems and components. Ter
18、ms and definitions For the purposes of ISO 8625, terms have been given a two-element number: the first element refers to the number of the part of ISO 8625 in which the term is defined and the second element refers to the reference number of the term within that part. EXAMPLE 4.3.38 velocity vs. for
19、ce/torque characteristics the term “velocity vs. force/torque characteristics” is defined in ISO 8625-4 Terms are presented according to the alphabetical order of terms in English. 4.1 Control system classification 4.1.1 adaptive control system control system which improves system performance by cha
20、nging system parameters in response to varying operational conditions 4.1.2 AFCS automatic flight control systems systems consisting of electrical, mechanical and hydraulic components that generate and transmit automatic control commands, which provide pilot assistance through automatic or semiautom
21、atic flight path control or which automatically control airframe response to disturbances NOTE 1 This classification includes automatic pilots, stick or wheel steering, autothrottles, structural mode control and similar mechanizations. NOTE 2 AFCS functions include, but are not limited to, airspeed
22、hold, automatic navigation, all weather landing, automatic terrain following, altitude hold, heading hold, altitude select, heading select, attitude hold (pitch and roll), lateral acceleration and sideslip limiting, automatic instrument, low approach mach hold, automatic carrier landing, automatic v
23、ectoring modes. BS ISO 8625-4:2011 ISO 8625-4:2011(E) 2 ISO 2011 All rights reserved4.1.3 autobrake automatic/electronic control of braking of a specific energy level 4.1.4 autoland automatic/electronic control that takes the aircraft all the way to a full land 4.1.5 autothrottle control means which
24、 sets a given position to maintain thrust for a given attitude/speed combination 4.1.6 bistable control system control system in which the control output is fully on in either polarity NOTE When the time is modulated by the input, the system is called pulse width modulated (PWM). The terms “ON-OFF c
25、ontrol” and “bang-bang control” are sometimes used. These types of controls pertain to digital controls. 4.1.7 closed-loop control system control system in which measurement of the output parameter is used to make system corrections so as to maintain a desired output based on input commands 4.1.8 CA
26、S control augmentation system vehicle flight control system wherein the control system responds to the error between commanded vehicle motion and the actual vehicle motion as well as to surface position command inputs 4.1.9 control and stability augmentation system combination of CAS (4.1.8) and SAS
27、 (4.1.20) 4.1.10 control authority total amount of control surface or force effector deflection available to a flight control system NOTE The prefixes “pilot”, “CAS” or “SAS” are often used to define that part of the total available to the pilot, the CAS or the SAS, respectively. 4.1.11 control syst
28、em system in which deliberate guidance or manipulation is used to achieve a prescribed value of a variable NOTE A control system has at least one input and one output. 4.1.12 digital control system control system which uses digital signals and wherein the control information is digital 4.1.13 flight
29、 control systems systems that enable the controlled flight of aircraft, helicopters and missiles NOTE “Manual flight control systems” transmit pilot commands through mechanical components, though they often incorporate electrical components to augment the pilot commands. The term is also sometimes u
30、sed for those systems which transmit pilot commands to the surfaces mechanically, without power or force assistance. BS ISO 8625-4:2011 ISO 8625-4:2011(E) ISO 2011 All rights reserved 34.1.14 fly by wire (FBW) system control by wire (CBW) system control system wherein control information and signals
31、 are transmitted completely by electrical means 4.1.15 fly by light (FBL) system control by light (CBL) system control system wherein control information is transmitted by light through a fibre optic cable NOTE A true FBL system does not have FBW or mechanical backup, nor FBW or mechanical override.
32、 4.1.16 hydraulic boost use of hydraulic power actuation to reduce the pilot effort needed for control of a vehicle wherein the actuator output force or torque is in direct proportion to the manual, mechanically applied, input force or torque 4.1.17 integral control system control system, which uses
33、 an integrator in the control loop elements to provide an output response to the error signal, and for which the control effort is proportional to the integral of the error 4.1.18 open-loop control control system in which an output is produced in direct response to a command, without feedback from t
34、he output being used to affect the system response 4.1.19 proportional control system control system which uses proportional control elements in its forward or feedback control paths, or both, to provide an output in response to the error signal 4.1.20 SAS stability augmentation system portion of a
35、flight control system that improves the handling characteristics by modifying the aerodynamic response of the vehicle NOTE The SAS generally has limited authority. SAS signals are normally introduced by a series servo, the operation of which does not have an impact on the pilots command signal. 4.1.
36、21 tristable control system control system in which the power to control the load is fully on in one polarity, off, or fully on in the other polarity (tristable) NOTE When the time is modulated by the input, the system is called pulse width modulated (PWM). The terms “ON-OFF control” and “bang-bang
37、control” are sometimes used. These types of controls pertain to digital controls. 4.2 Control system technology (control engineering) 4.2.1 backlash uncontrolled load motion due to clearance in actuation elements, including the load attach point, usually expressed in terms of absolute load motion BS
38、 ISO 8625-4:2011 ISO 8625-4:2011(E) 4 ISO 2011 All rights reserved4.2.2 bandwidth frequency range over which the actuation system has acceptable dynamic response NOTE This spectrum extends from a base frequency up to a specified frequency, which is usually the frequency where the open-loop amplitude
39、 ratio has unity gain (0 dB) in other than single order systems. For a first order system, this is the frequency where the closed-loop response is down 3 dB and the phase lag is 45 see also decibel (4.2.6). 4.2.3 closed-loop frequency response frequency response between command input and control sys
40、tem output with the feedback signal summed algebraically with command NOTE Actuation system response for a closed-loop system is usually specified as closed-loop frequency response. 4.2.4 command input which represents the desired output of the control system 4.2.5 control passband frequency range o
41、ver which the control responds without attenuation 4.2.6 decibel dB unit of measure used to express amplitude ratio of output to control input NOTE Decibels = 20 log 10(amplitude out/amplitude in). 4.2.7 dynamic impedance impedance, a complex quantity, associated with the output deflections of an ac
42、tive, closed-loop actuation system caused by externally applied dynamic forces, usually sinusoidal, over a specific frequency range NOTE Dynamic impedance at the surface includes the effects of the surface attachment spring, its load mass and its viscous friction. The impedance at the actuator will
43、not include these factors. 4.2.8 error signal algebraic difference between the command input and the output feedback 4.2.9 feedback element component in a closed-loop system that provides the feedback signal of the output quantity, or a function of the output that can be compared with the reference
44、input 4.2.10 forward loop control elements elements situated between the error signal and the controlled variable 4.2.11 frequency response complex ratio of the actuation system output to the command input while the input is cycled sinusoidal at a constant amplitude and the frequency is varied NOTE
45、Frequency response is usually presented as a log frequency plot of normalized amplitude ratio, expressed in dB, and input to output phase angle degrees versus frequency. BS ISO 8625-4:2011 ISO 8625-4:2011(E) ISO 2011 All rights reserved 54.2.12 gain crossover point of the plot of the open-loop trans
46、fer function at which the magnitude is unity (LmG (j ) = 0 dB) NOTE The frequency at gain crossover is called the phase margin frequency, . 4.2.13 gain margin measure of system stability defined as the gain required to raise the open-loop amplitude ratio to 0 dB (unit gain) at the frequency correspo
47、nding to 180 of phase lag 4.2.14 hysteresis difference in actuation system output for the same input command level during a complete cycle of input command when cycled throughout the full range of travel NOTE It is necessary that the cycling rate be significantly below the control bandpass so that v
48、elocity error signals are not included in this parameter. 4.2.15 input independent variable supplied to the control system 4.2.16 linearity degree to which the normal output curve conforms to a straight line under specified load conditions, usually expressed as a percentage of full range, or sometim
49、es of rated output, which is typically half full range 4.2.17 load natural frequency undamped resonant frequency of the load mass, coupled with the frequency-independent dynamic stiffness 4.2.18 loop signal path in a closed-loop control system beginning with the error signal after a summing point and ending with the resultant feedback signal returning to the same summing point 4.2.19 normal output curve locus of the mid-points of a complete input/output curve NOTE This locus is the zero hysteresis
