Features Servo system comprises self-

contained units with mimicdiagrams of function blocks

Magnetic base on each unitprovides firm fixing to baseplateenabling pratical visualisationof system block configurations

Units may be investigated individ-ually before building a system

Easily extended to cover Digitalsystems

No mechanical skills required toconstruct a working system

Hands-on assembling of workingsystems

Variable factors such as gain,damping, friction and inertia areimmediately demonstrable by theireffect on performance

Demonstrations of stable andunstable modes by using switch-intime constant network

Speed or position configurationsmay be built

System protected against incorrectconnections and accidental short-circuits

DescriptionThe MS150 Modular Servo System is a unique equipment designedto study the theory and practice of automatic control systems.It has been designed for teaching the theory of open and closed-loop,speed and positional control systems using modular units, bothmechanical and electronic, that can be configured to demonstratethe various methods of control techniques.The MS150 comprises a baseplate and twenty units (see pages 7and 8) which can be supplied as:

z a complete system MS150-3z a dc system only MS150 (see page 2)z an ac system only MS150A (see page 3)z as a Digital system in a MATLAB environment 33-008 orz conversion sets to enable a change from one system

to another (see page 4)Each unit is fitted with a magnetic base which holds the unit to theplastic coated steel baseplate, irrespective of the angle at which thebaseplate is positioned. Individual units may be so arranged to createoperating block schematic systems and interconnections between theunits are made by jumper leads terminated in 4mm stackable plugs.The modular concept of the MS150 system permits the study ofindividual units and also, by combination, the investigation andperformance testing of complete systems.A series of instructional manuals (see page 6) is supplied to providecomprehensive coverage of servo system theory and assignments fora wide range of student abilities.

Modular Servo Instructional Servo System MS150

DC ModularServo SystemMS150The d.c system MS150 is the basicset from which all other systems arederived. It is used for demonstratingand teaching automatic controltechniques to students andtechnicians at all levels, e.g.Technical and Craft schoolsScience and Physics coursesIndustrial training coursesUniversities, Teachers TrainingColleges, Military Training Schools,etc.The MS150 comprises modularunits for individual study andconstruction of speed and positioncontrols using d.c error signals.The MS150 system is extendibleto cover:l AC servo systemsl Hybrid servo systemsl Digitally controlled servo systemsl Relay (on/off) servo systemsl Sampled data systemsl Three-term controlModules supplied are listed in thetable on page 8.Demonstrations andAssignmentsThe practical work is covered in theinstruction manuals by Books 1and 3. Book 1 (Basic) is largelyqualitative and covers the initialintroduction to control systems.Most work is non-mathematicaland in the few cases where someknowledge is required, the formulaeare of the elementary kind.Assignments include:l Operational amplifiersl Motor speed characteristicsl DC error channell Simple position controll Closed-loop position controll Simple speed controll Deadband and Step Responsel Velocity feedback

Book 3 (Advanced) assumes theability to understand simpledifferential equations and theoperator j.Investigations include:l Analysis of simple position control

- speed responsel Position responsel Closed-loop frequency responsel Measurement of motortime

constant

l Measurement of velocity errorconstant

l Frequency & transient responsel Measurement of following errorl Stability considerations & the use

of lead, lag & combined networksl Tacho-generator feedback and its

effects on system performanceincluding acceleration feedback

l Linearisation of system

Tender Specification for MS150Modular servo trainer to permit con-struction and study of d.c. position andspeed control systems of various types.To provide for external input, viscousand inertia loading and variation ofprincipal parameters. To include threeinstruction manuals with basic theoryand at least twenty practical activitieson component characteristics, open andclosed-loop behaviour & compensationtechniques.

Ancillary EquipmentTo cover the full range ofdemonstrations and experimentalwork a function generator and ameans to display the dynamicresponses are essential.

Feedback function generator FG601is suitable. We recommend that thedisplay oscilloscope has d.ccoupled X and Y channels and hasa simple storage facility.

Speed Control

Position Control

AC ModularServo SystemMS150AThe ac system MS150A is used inmore specialised and advancedcontrol engineering courses wheresome detailed knowledge of accarrier systems is required. It has thesame basic form as the dc systemand in fact uses some commoncomponents. As ac systems arefundamentally more complex than dcsystems the theoretical work possiblewith the MS150A is to a higher levelthan that for the MS150 dc system.The MS150A will have particularrelevance to control engineering forMilitary and Aviation schools and foruniversities and colleges catering forthe aerospace and advancedelectronic industries.Demonstrations & AssignmentsThe Instruction Manuals containprogressive exercises with fulltheoretical explanations at eachstage, commencing with a simpleintroduction in Book 1 and leading tomore advanced work in Book 3.l Motor characteristicsl AC tacho-generatorl Motor speed controll AC pre-amplifiersl Position control systeml The importance of correct phasing

on performancel Compensation using the

adjustable notch filterl Notch filter design exercisesl Frequency selective

characteristics for the eliminationof noise and harmonics

l Detailed analysis of carriersystem

l Frequency transformation forcompensator techniques

l Principles and measurement ofcompensation unit characteristics

l Measurement of systemcharacteristics

l Instabilityl Reduction in steady following error

Ancillary EquipmentSimilar ancillary equipment to thatdescribed for the dc modular servosystem MS150 is required (seepage 2). AC systems are howevermore complex than d.c systems soit is strongly

Tender Specification for MS150AModular servo trainer to permit construction and study of carrier typeposition and speed control systems of various kinds. To provide forexternal input, viscous and inertia loading and variation of principalparameters. To include three instruction manuals with at least eightpractical activities and a theoretical discussion of dynamics, phasingand compensation by notch networks.

recommended that a variable-phase function generator e.g.Feedback VPG608 and a dual-beam oscilloscope be used formaximum benefit.

AC Position Servo System

Modular Servo Conversion SetsThe dc system MS150 and ac system MS150A described on pages 2 and 3 are completely self-contained.They do however contain common components and thus it is possible to convert from one system to theother at minimal cost, providing in one package both ac and dc systems. Conversion sets providing thisfacility are described below; these extend the work beyond individual dc and ac systems.

Conversion from ac to dc systemsCustomers in possession of the acModular Servo System MS150A whowish to extend their practical workto include dc systems will need topurchase the three units 150F,150H and 150C.Tender Specification for 150CFHSet of units to convert a carrier-typeservo system to a dc system.To provide reference potentiometer, dcmotor and dc pre-amplifier.

150RST consists of three unitswhich enable the basic d.c MS150to be converted to an a.c/d.c hybridservo typical of many found inindustrial processes.Range of AssignmentsWhen used in conjunction with theMS150 the 150RST produces a

continuous rotation position controlsystem with ac error channel usingtwo synchros and a demodulator.These three units enable mainlyqualitative assignm ents (Book 3) tobe carried out; they cover exploratorywork on synchros for datatransmission and on associated

equipments.l The synchro linkl The demodulatorl Error channel sensitivityl Closed-loop systeml Steady state following velocity

feedback effectl Improved steady state following

with acceleration feedbackl Use of synchro link with defined

time constant system.Tender Specification for 150RSTSet of units to provide a dc servosystem with an ac error channel basedon synchro components. To providesynchro transmitter and receivertogether with demodulator to convertac error to dc. To include teaching textwith at least six practical activities andtheoretical discussion of dynamiccharacteristics of synchro link servos.

Range of AssignmentsThe assignments demonstrate thegeneral characteristics of acsystems in a qualitative manner.They include:l Characteristics of a two-phase

motorl General behaviour of a closed-

loop systeml Effects of gain and damping on

stability

l The importance of correctphasing on torque and speedcontrol

l Compensation using theadjustable notch filter

l Notch filter design exercisesl Frequency selective charac-

teristics for elimination of noiseand harmonics.

Tender Specification for 150UVWSet of units to convert a hybrid (acerror link) servo system to full acoperation. To provide an ac motor, acpre-amplifier and an ac compensationfacility. To include teaching text with atleast eight practical activities togetherwith a theoretical discussion of thedynamics of carrier servos, of phasingand of compensation by notchnetworks.

AC/DC Hybrid System using Conversion Units 150RST

AC System using Conversion Units 150UVW

These three units when used inaddition to the 150RST units andthe dc MS150, fully convert the ac/dchybrid system into a suppressedcarrier ac system. The system usesa two-phase motor (150U), an acpre-amplifier (150V) and a compen-sator unit (150W). The equipment issupplied with full theoretical explan-ations and suggested courses ofpractical work (Book 3).

Demonstrations & AssignmentsPractical work which can be carriedout with the SR150G in conjunction

1. Deadband with variable slope.2. Backlash with fixed unity slope.3. Two-step and three-step without

hysteresis (overlap).4. Two-step and three-step with

hysteresis (overlap).

Tender Specification for SR150GAdd-on unit to adapt linear servo systemto teach non-linear behaviour. To providedeadband, hysteresis, backlash, 2-step& 3-step characteristics, all with variableparameters. To include teaching textwith at least six practical activities andintroduction to phase-plane analysis.

A further add-on unit is the PID150Ythree-term control unit which can beused also with other d.c controlsystems. It provides a practicalprogramme covering proportional,integral and derivative functions.Each path in the unit can be isolatedfrom the others and is accessiblevia a monitoring socket. The threepaths are combined in a summingamplifier with low-pass filtering

Proportional, Integral & Derivative unitPID150Y

with the MS150 DC Modular ServoSystem is given in Book 4:l Relay characteristics-deadband -

hysteresisl Relay-operated control systeml Following characteristics of relay

systeml Effect of backlash on system

stabilityl Relay-operated speed-control

systeml Phase-plane analysisl Motor characteristics - trajectoriesl Trajectory for a sequence of

switchingsl Phase-plane analysis of relay-

operated systemsl Rotation of switching lines by

velocity feedback

characteristics, and an inverter isused to give 0 and 180 outputs.Variable time constants are pro-vided in the integral and derivativefunctions to allow investigation ofcontrol loop characteristics.The instruction manual covers:l Speed control of an MS150 servol Position controll Following errorl Temperature control using the

Feedback Process Trainer PT326l and Appendices on PID control.

Tender Specification for PID150YAdd-on unit to provide full three-termcontrol facilities for dc servos and othercontrol system tutors. To provide prop-ortional, integral & derivative error com-ponents all with variable parameters.To include teaching text with at least fourpractical activities and suggestions forfurther work and a theoretical intro-duction to three-term control techniques.

Simulated Relay Unit SR150G

Hybrid System

AC System

Additional Units

The SR150G is an additional unitwhich greatly increases the scopeof the dc MS150 by converting it intoa relay (bang-bang or on-off) typecontrol system with 2-step & 3-stepcontrol characteristics; it provides awide range of electronically genera-ted non-linear characteristics. TheSR150G may also be used on itsown to demonstrate the character-istics detailed below. The unit isprovided with selector switches andcontrols that allow the generation ofthe following characteristics: Inputdrive voltage 10V triangle wave-forms at 5Hz nominal frequency.

Sample and Hold Unit SH150M

Instruction ManualsBook 1 - dc, Synchro, and ac Basic

AssignmentsBook 2 - Circuit Notes and

MaintenanceBook 3 - dc, Synchro and ac

Advanced Experiments

Book 4 - Simulated Relay SystemSR150G

Book 5 - Sample and Hold unitSH150M

Book 6 - Three-term control unitPID150Y

The addition of this unit to theMS150 dc Modular Servo Systemdemonstrates the application of theprinciples of sampling theory tocontrol systems. The unit consistsof a zero order hold circuit andcompatible pulse generator. Thegenerator has an operating rangeof 0.1 to 100Hz in three decades.The unit has the standard MS150module case with magnetic baseand mimic diagram of the basiccircuit. Assignments that form partof the accompanying manual(Book 5) include:l Waveform samplingl Sampled data servo control systeml Simulated sampled data control

system

l Sampled data process controlsystem with Appendices onTransfer functions of HoldCircuits, and the SamplingTheorem.

As the SH150M is fully compatiblewith most of the Feedback controlsystems, this means that there is awide range of possible uses for theunit including demonstration of theapplication of Z-transforms.Tender Specification for SH150MAdd-on unit to adapt linear servosystems for zero-order hold sampled-data studies. To provide variablesampling rate and full trigger facilities.To include teaching text with at leastfive practical activities and introductionto sampled data theory.

Differential Synchro DS150JThe DS150J is a differential synchrounit for use with the MS150A acModular Servo System. It is used inconjunction with the ST150Tsynchro transmitter and ST150Rsynchro transformer fordemonstrating synchro operation.The DS150J is similar inappearance to the ST150R but it isfitted with a differential synchro inplace of the synchro transformerand has a knob to set thedifferential angle. It can be insertedin the normal link between theST150R and ST150T to illustrate thepositioning of a transformer to anangle equal to the difference

between the angles set on thetransmitter and differentialsynchros.As there is an internal torquegenerated which tends to align therotor and stator to zero differential,the dial is fitted with a braking pad.Six connections, three rotor andthree stator, are brought out to thetop panel.Tender Specification for DS150JAdd-on unit for hybrid and ac servosystems to illustrate the use of adifferential synchro with other synchrocomponents. To include operatinginstructions and suggestions forpractical work.

Description of MS150 UnitsOperational Amplifier Unit OA150AA general-purpose amplifier with fac-ilities for multiple inputs and variousfeedback arrangements. Uses includesummation to produce operating error forclosed-loop systems, addition of extratime constants to demonstrate instability.Attenuator Unit AU150BTwin calibrated potentiometers mountedin one case, available for gain and tacho-feedback control.Pre-Amplifier Unit PA150CHas two input channels and a push-pulloutput for direct drive of the servoamplifier. Gain approx 25. Includes aswitched defined time constant network.Servo Amplifier SA150DOperates the motor to which it may beconnected via a 12-way socket.A protective circuit limits the motorcurrent under overload conditions.Power Supply PS150ESupply input tappings are 100V, 110V,120V, 200V, 220V 240V, 50/60Hz, 40VA.Output 24V dc, 2A unregulated, con-nects directly to the servo amplifier viaa 12-way socket. Stabilised dc at 15V,150mA on 4mm sockets to operatesmaller amplifier units and to providereference voltages. 9V-0-9V rms atsupply frequency on 4mm sockets tooperate an ac error channel. 18V rmsat supply frequency provide referencephase.dc Motor Unit DCM150FThis is a permanent magnet motor.The motor shaft is extended for directmounting of the magnetic brake andinertia discs. Complete with the followingaccessories:1 Inertia disk (thick).1 Hexagonal spacer with hubs & collars.1 Shaft 30mm long.Simulated Relay Unlt SR150GConverts the dc MS150 into a relay(banging or on-off) type control systemwith 2-step and 3-step controlcharacteristics; it provides a wide rangeof electronically generated non-linearcharacteristics.Input & Output PotentiometersIP150H & OP150KSemi-precision, servo-typepotentiometers, mounted and fitted withcalibrated position indicating dials.The output unit carries a rear extensionshaft for coupling directly to theReduction Gear Tacho Unit.Differential Synchro DS150JA size eleven synchro of standardmechanical dimensions for use inconjunction with the ST150R andSR150T units.

Loading Unit LU150LComplete with Brake disc (thin). A fittingfor the shaft mounts the aluminium discwhich runs between the poles of aseparately mounted permanent magnet.The pole/disc interference area may beadjusted against an arbitrary scale toprovide a variable viscous load for themotor.

Sample and Hold Unit SM150MConsists of zero order hold circuit andcompatible pulse generator withoperating range of 0.1 to 100Hz inthree decades.Synchro Transformer Unit ST150RA size 11 synchro of standard mech-anical dimensions and fitted with calib-rated position-indicating dial including astroboscopic disc; it is coupled directlyto the motor low-speed output shaft bythe Feedback coupler provided.Modulator/Demodulator MD150SThe demodulator section is a phase-sensitive rectifier & filter unit for use on50 or 60Hz carriers. It has an adjustablephase-shift network covering 0 tonearly 180 to correct the referenceinput. In the demodulate condition thebandwidth is about 5Hz with the filterconnected; with the filter off,experimental filters may be connected.The modulator section, with a bandwidthof about 60Hz, may be switched in toreplace the demodulator, and is used inconjunction with the operational amplifierunit OA150A for injection of suppressedcarrier test signals into the system.Synchro Transmitter Unit ST150TA size 11 synchro of standardmechanical dimensions. Also containsan auxiliary drive motor, the armature ofwhich is energised by an emitterfollower, the speed being controlled bya potentiometer. The maximum speed isabout 80 rev/min and the stroboscopictrack on the calibrated dial permitsaccurate adjustment down to 1 rev/sec.ac Motor ACM150UA two-phase ac induction motor whichconnects via a 12-way plug to theservo-amplifier. Reference and controlphases are also connected to socketson the front panel so that the motorwaveforms can be monitored. A resistorin series with the reference phase limitsthe current during normal use.The modulator circuit transforms a dctachogenerator signal (direction = dcvoltage polarity and speed = dc voltagemagnitude) into an ac tacho signal(direction = signal phase with respect tomotor ref. phase ie. in phase or anti-phase and speed = magnitude).The phase adjust control allows fineadjustment when the complete systemis set up.The motor shaft is extended for directmounting of the magnetic brake andinertia discs. Complete with thefollowing accessories:1 Inertia disc (thick).1 Hexagon spacer with hubs & collars.1 Shaft 30mm long.2 Spanners DE OJ, 18 x 19mm.ac Pre-Amplifier PA150VThis unit precedes the servo amplifier150D (see diagram - page 4). It hasfacilities for summing the signals fromtwo channels, one of which has aphase-adjusting control coveringapproximately 0 - 180. An active filternetwork is available for use in thecompensation experiments. This givesan analogue of a phase advancenetwork when applied to the ac system.

ac Compensator Unit CU150WThis unit provides transfers of thegeneral form:

representing a pair of complex poles inthe denominator and a pair of complexzeros in the numerator, as indicated inthe s-plane plot. The zeros can bemoved from the left-half on to theimaginary axis (to give carrier rejection)and into the right-half plane to illustratenon-minimum phase characteristics.The poles can be set to the imaginaryaxis to give a sharp notch or resonancecharacteristic (bandwidth 1Hz). Thecentre frequency can be tuned to50 or 60Hz carrier.

Reduction Gear Tacho Unit GT150XThis contains a 30/1 ratio speedreduction gearbox and a dc tacho-generator driven from the high speedinput shaft. A top panel display can beswitched to indicate speed in r/min or tomonitor an external dc voltage. Completewith the following accessories:2 Hexagonal coupling, each completewith four o rings.PID Unit PID150YThis is a proportional plus integral plusderivative control unit for use withMS150 or other Feedback controlsystems using dc electrical signals.Ancillary Items MS150ZComprises:1 Plastic coated steel baseplate.8 Leads 4mm plug, 165mm, yellow.4 Leads 4mm plug, 165mm, grey.4 Leads 4mm plug, 270mm, red.6 Leads 4mm plug, 270mm, orange.2 Leads 4mm plug, 270mm, green.6 Leads 4mm plug, 270mm, grey.7 Leads 4mm plug, 570mm, yellow.2 Leads 4mm plug, 570mm, green.4 Leads 4mm plug, 570mm, grey.6 Leads 4mm plug, 3 core.2 Spanners DE OJ 1/4 x 3/16" BS.

;

Power Supply requirements PS150E Power supply - tappings at 100V, 110V, 120V, 200V, 220V, 240V50/60Hz. All other modules require power of 15V, 18V and 9-0-9V ac,50/60Hz supplied from the PS150E.

Connections All connections via 4mm sockets. Power supply connections in three-leadflexible loom.

Mounting By magnetic bases onto plastic-coated steel baseplate, 720 x 520mm.Table 1 Ordering Information

Modular Servo Systems Units supplied with each equipmentMS150 dc system A B C D E F G H J K L M R S T U V W X Y ZMS150A ac system A B C D E F G H J K L M R S T U V W X Y ZMS150-2 ac/dc system A B C D E F G H J K L M R S T U V W X Y ZMS150-3 Complete Modular Servo A B C D E F G H J K L M R S T U V W X Y ZFor customers who would like to upgrade their existing MS150 system to be used with MATLAB software (33-008), there is anUpgrade Pack 33-310-PCI available. It is not possible to upgrade very old versions of the MS150, so please contactFeedback Instruments or your local representative for advice on the best upgrade path if required.

Conversion sets150CFH from ac to complete ac/dc A B C D E F G H J K L M R S T U V W X Y Z150RST from dc to ac/dc hybrid A B C D E F G H J K L M R S T U V W X Y Z150UVW from hybrid to fully ac A B C D E F G H J K L M R S T U V W X Y Z150RST/UVW from dc to fully ac A B C D E F G H J K L M R S T U V W X Y ZAdditional unitsSR150G Simulated Relay A B C D E F G H J K L M R S T U V W X Y ZDS150J Differential Synchro A B C D E F G H J K L M R S T U V W X Y ZSH150M Sample and Hold A B C D E F G H J K L M R S T U V W X Y ZPID150Y PID Control A B C D E F G H J K L M R S T U V W X Y ZMS150Z Base unit and accessories A B C D E F G H J K L M R S T U V W X Y ZOther combinations of sub-units can be supplied, quotations available on request.

Approximate Dimensions (mm) and Weight (kg)Equipment Unit pack Equipment Unit pack

Width Depth Height Weight Width Depth Height WeightMS150-3 720 520 203 24.4 150UVW 267 204 153 3.9MS150-2 720 520 203 22.9 SR150G 107 107 67 0.33MS150 720 520 203 17.5 DS150J 100 104 133 0.42MS150A 720 520 203 20.0 SH150M 107 107 67 0.34150RST 267 204 153 1.5 PID150Y 107 107 67 0.36Quantities packed for shipment are not necessarily multiples of figures given for each unit packs as packing varies with number of units ordered.

Tender Specifications MS150-3 - An instructional ac, dc or hybrid servo system in modular kitform, to teach the theory and operation of control system engineering.To include five instructional manuals.MS150-2 - An instructional ac or dc servo system in modular kit form, toteach the theory and operation of control system engineering.To include two instructional manuals.MS150 - An instructional dc system in modular kit form, to teach the theoryand operation of control system engineering. To include two instructionmanuals providing at least 10 assignments.Tender specifications for the Conversion sets and additional units areincluded within the leaflet.

Ordering Information Complete Modular Servo System MS150-3 or any combination of units fromtable 1 above.