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DESIGNERS' HANDBOOK FOR ELECTROHYDRAULIC

SERVO AND PROPORTIONAL SYSTEMS

 

Preface to the Fourth Edition

 

This is the Fourth Edition of this book, which was originally published under the title of Introduction to Design of Electrohydraulic Circuits Using Servo and Proportional Technology. Enough was added in Third Edition that the change in title was felt to be justified, but the title will remain for this edition.

 

This book supplements a lecture series on the design of electrohydraulic circuits and systems. In this context, systems design consists of the selection, matching and interconnection of a variety of components from a variety of technologies in order that the system performs to a given set of specifications. Normally, a reasonably complete treatment of the subject requires about two semesters of college level effort, however, an overview can be gained in two or three full days, if diligence is the rule of the day. It is hoped that the student and/or the reader will realize that this work represents only an introduction to a subject that many of us have spent a career trying to master, and at times, when attempting to get a particularly troublesome system up and running, we have all wondered if we have gotten very far.

 

This book IS NOT heavy on theory. Quite the contrary. It is intended to be a concise summary of the technology, and derivations for the most part and theory have been replaced by a number of completely solved example problems that are scattered throughout the book. About half the theory, should the student be encouraged to pursue it, will be found in the book: Design of Electrohydraulic Systems for Industrial Motion Control Systems, 2nd Edition, 1995. The other half of the theoretical background is contained in scores of file folders of unpublished chapters in my office.

 

There have been several attempts to offer a way of looking at hydraulic circuits which somewhat parallels my own electrical engineering education. The first is that constant pressure systems and valve control cannot be approached from the point of view of the conventional hydraulic circuit that uses positive displacement pump control. Prior exposure to conventional hydraulic circuit design can be both helpful and a hindrance. All too often, we fall into the trap of thinking that positive displacement pump control is a first principle from which all other principles flow. Quite the contrary. We learn, for example, that in constant pressure, valve control, that single rod end cylinders extend faster than they retract, a reality in the classroom that is at once frustrating, but at times, entertaining. Secondly, the analytical schematic has been introduced, because the industrial symbol set, which we are taught, if not heaven-sent, then Geneva will have to do, is all that is needed in order convey concepts. This simply not the case. The symbols must be used in different, unconventional ways, and I find, it is necessary to create, for example, orifices which convey the difference between turbulent and laminar flow regimes. Thirdly, it is essential to distinguish between ideal components, especially in pumps and motors, and practical components. The concept of an ideal component is a great teaching tool, because it forms a clear idea of what we would like to achieve with our components, the ideal, and then we proceed from there to explain with more complex models, how real components behave. But, by using symbology that distinguishes the difference, the reader should be very certain of the nature of the model that is at hand. Clearly, we all use both real and ideal models, but methods for distinguishing the two have never been adopted. For clarity, I feel that it is essential that readers know the kind of device that is being dealt with at the point of discussion. The distinctions between real and ideal are clear. Therefore, the concept of ideal and practical components is introduced.

 

Next, there is significant emphasis placed on the pressure metering characteristics of valves. Conventional hydraulic training does not usually take up the issue, and yet, it is impossible to understand servo and proportional valves without understanding the way that the pressure metering characteristics interact with the actuator and load. When pressure metering concepts are mastered, it is a short step to understand why there are errors in servo mechanisms, how they can be contained, and why we design systems around the error containment process. The statement, "the load stops because the force on the actuator comes into balance, therefore the flow stops, not the other way around" makes sense, and, of course is true.

 

And then, once the errors are understood, one of the most profound realities is, that it is possible to relate them to the frequency response, or, bandwidth of the system and the components. It then leads to another major gremlin lurking in every feedback control system, that of instability, or sustained oscillations. It is necessary that the system designer contain the errors in order to achieve the necessary performance, however, the system cannot be allowed to go unstable. If the student cum reader will master pressure metering of proportional and servo valves, then all the rest flows naturally from it.

 

I have found through the years of teaching this subject that if the theory is to be covered, then it must be done so in detail, and a book that is heavy with theory will tend to bury the reader in analytical chaff, when interest may consist only of an overview. For this reason, the theory has been reduced, and the end results presented, with examples. That is, the book uses the principle that the student learns by doing. There are scores of fully worked example problems. These should be studied in detail and will help in understanding the concepts, plus, it will help in defining the various elements of a given equation or formula and it will help to focus attention on the most important part of learning, where do you look for the information you need to solve the problem? The number of worked example problems has more than tripled from the second edition to this.

 

Several chapters were added in the Third Edition. Two of them are devoted to the pressure compensated pump, which is a vital part of the electrohydraulic motion control servo system. Constant pressure is a necessity, and the P-Comp pump is the means to that end, along with the flow-augmenting accumulator. The first of the two chapter deals with modelling and applying the pressure compensated pump. The second added chapter is a summary of the results of simulating the dynamic response of the pump and various sized accumulators. The objective is to come away with a sensible procedure for estimating the size of the accumulator in order to achieve a specified dynamic pressure regulation target.

 

The Third Edition also added a chpater on Block Diagrams and Transfer Functions. Although the theory behind transfer functions, generally is beyond the scope of the technical level of this book, I felt it was needed in order to be a complete reference for both engineers and technicians who are forced to deal with feedback control systems. The chapter can be safely ignored by those who wish to do so, but it is there should the reader be interested.

 

Eighteen new, fully worked example problems were added to the chapter on Cylinders. Anyone interested in understanding how valves control the motion of cylinders is urged to master these problems before proceeding. The chapter on Valve Control of Cylinder Motion will be easier to deal with.

 

And lastly, the Third Edition discussions of electricity and electronics has been expanded. A few more items of interest o mobile equipment users have been included, such as joysticks. In the aim of decreasing dependence on the standard temperature-viscosity charts, a chart of Walther coefficients for more than 500 commercial hydraulic fluids has been added. Viscosity can be calculated directly from a knowledge of the fluid and temperature.

 

The Fourth Edition is the result of your continuing requests for a more complete handbook. Toward that end, the first chapter is completely new and provides a more fundamental approach to the Physics of Hydraulics, and of course, is replete with fully worked example problems. There was a call for more insight into analysis of loads that are encountered in the application of hydraulic fluid power. The call was answered by adding three chapters devoted to that subject, but the approach is one of meeting the needs of motion control, more than an exhaustive dissertation on Statics, Dynamics and Kinematics. Again, there are several worked problems in each chapter.

 

And there was a call for more explanations regarding the ever-present and ever-expanding electronic gadgets that motivate and control all the wonderful electrohydraulic machines. The electronic subjects have more than doubled, and even includes a section devoted to special topics about electronics for mobile hydraulics.

 

I want to thank Tom Wanke, Director of the Fluid Power Institute, Milwaukee School of Engineering, who reviewed parts of the manuscript and offered valuable insights and corrections to the subject of filtration and contamination control And I must thank my wife and love of my life, Louise, as well as the rest of my family, who endured inattention, if not an outright alienation, while I sat at the desk or keyboard for long hours, that ran into days and months. It was Louise who did the initial typing and layout and equation setting in the first three editions. The other family members also deserve a toast of gratitude for the help and inspiration that they gave through those long months. Especially helpful has been my youngest son, Brian Johnson, to whom was delegated all the work on the Walther coefficients, including their calculation and keyboard entry. Brian also was responsible for working all the example problems and documenting the processes. My Granddaughter, Rebecca Barr, to whom befell so much of the keying, dutifully set all the type in her little computer for this Fourth Edition.

 

Yes, electrohydraulic system design using servo and proportional valve technology is an analytical and, at times, a challenging process, however, successful implementation is rewarding and satisfying all by itself. The future will see more of this stuff put to good use, not less. There is a future for anyone who sets out to master the technology. So, review the contents with the idea that you are embarking an exciting technological adventure. It is not an end, only a beginning. Good luck!

 

Jack L Johnson, BSEE, PE

East Troy WI

 

  DESIGNERS' HANDBOOK FOR ELECTROHYDRAULIC SERVO AND
PROPORTIONAL SYSTEMS

TABLE OF CONTENTS

(1) PHYSICS OF HYDRAULIC FLUID POWER

UNITS OF MEASURE

ARBITRARY UNITS AND SYSTEMS OF MEASURE

Time

Length

Mass and Force

DERIVED UNITS OF MEASURE FOR HYDRAULICS

Area

Volume

Velocity

Acceleration

Flow

Pressure

Angle

Angular velocity

Angular acceleration

Torque

Mass Moment of Inertia

Work

Energy

Power

FLUID PROPERTIES

Density

Specific weight

Specific gravity

Viscosity

Absolute viscosity

Kinematic viscosity

SAYBOLT UNIVERSAL SECONDS

The affect of temperature on viscosity

Bulk Modulus

Fluid statics

Pressure exerted by a column of fluid

Atmospheric pressure and absolute pressure

Vacuum pressure

Vapor pressure

Cavitation

HYDRAULIC CYLINDER PERFORMANCE CALCULATIONS

Output force

Cylinder Area Notation

Speed and Flow

Hydraulic cylinder Work and Power

FLUID DYNAMICS

Flow through an orifice

Accounting for energy losses using dimensionless coefficients

Expressing orifice resistance in terms of Kv "Holes"

Flow and pressure loss through a tube

General steady-state, steady-flow energy equation

Conservation of mass

D'Arcy pressure drop equation

THE MOODY DIAGRAM

Solving for pressure drop through pipe, tubing, and hose

Hagen-Poiselle law for laminar flow

Colebrook Equation (for turbulent flow)

CIRCUIT FLOW AND PRESSURE DROP

Flow through orifices in series

Flow through orifices in parallel

Flow through 90 and 45 degree elbows

PRESSURE LOSS COEFFICIENT FOR PIPE ELBOWS

Flow through reductions and expansions

Sudden contraction in flow path

Flow path expansion

Laminar flow through paths in Series

Turbulent flow through paths in series

Generalized flow through paths in series

Flow Q, is known, calculate DP

Pressure loss observations

Introduction to Power Sources

Introduction to 4-way spool valves


(2) PHYSICS OF MECHANICAL LOADS

FIVE DESIGN TIME DECISIONS

NEWTON'S LAWS

ONE DIMENSIONAL MOTION

FOUR COMPONENTS OF FORCE

Forces That Oppose Acceleration

Forces That Oppose Velocity

Friction

Forces That Oppose Position

Pendulous Effects

Spring Force

Energy Storage in a Spring

Constant Load Forces

COMBINING FORCES ON A FREE BODY

FORCE WAVESHAPES

LINEARIZED VISCOUS COEFFICIENT

ROTATIONAL MOTION VIS--VIS LINEAR

            (TRANSLATIONAL) MOTION

TABLE I COMPARISON OF LINEAR AND ROTATIONAL MOTION PARAMETERS AND VARIABLES

 

(3) MECHANICAL TRANSFORMATION DEVICES

REFLECTING LOADS THROUGH THE TRANSFORMER

OTHER MECHANICAL TRANSFORMING DEVICES

Power and Performance Considerations in the Conveyor-Elevator

Inertia at the Shaft of the Conveyor

Non-Accumulating Conveyors

Belts and Pulleys


(4) NON-LINEAR TRIANGULAR LOAD TRANSFORMATION

EQUIVALENT MASS

MASS POLAR MOMENT OF INERTIA

PARALLEL AXIS THEOREM

SPRING-INERTIA RESONANCE METHOD OF DETERMINING INERTIA EMPIRICALLY

PENDULOUS RESONANCE METHOD OF DETERMINING INERTIA EMPIRICALLY

IN-POSITION LOAD HOLDING FORCE

LOAD RESONANCE

 


(5) HYDRAULIC CIRCUIT ANALYSIS FUNDAMENTALS

            INCH-POUND-SECOND SYSTEM - AN EDITORIAL COMMENTARY

CONSISTENT UNITS EMI

UNITS PREFIXES EMG

TEMPERATURE AND TEMPERATURE SCALES

PRESSURE AND FLOW

FLUID COMPRESSIBILITY

KIRCHOFF'S LAWS APPLY TO HYDRAULIC CIRCUITS

PRESSURE-FLOW CHARACTERISTICS OF ORIFICES

Laminar Fluid Flow

Figure 2 - Laminar Pressure-flow relationships for common geometric passages, based upon the Hagen-Poiseuille Law.

THE "KNIFE-EDGED" ORIFICE AND TURBULENT FLOW

COMBINING ORIFICES

PRESSURE DROP

HYDRAULIC AND MECHANICAL POWER

CONVERSION OF FLOW UNITS

 

(6) FLUIDS AND CONDITIONING SUBSYSTEMS

FILTERS

Beta Ratio

RESERVOIRS

HEAT EXCHANGERS

FLUIDS

Viscosity

Bulk Modulus

Hydraulic Capacitance

ACCUMULATORS

Adiabatic Case

Adiabatic Hydraulic Capacitance

Iso-Thermal Case

Accumulator Placement in the Circuit

MATERIAL PROPERTIES

PLUMBING

Table I - PROPERTIES OF MATERIALS

Table 2 - SERVO VALVE FOOTPRINT CHART

            Figure 4 - Summary Chart for Viscosity

Table 3 - WALTHER FORMULA COEFFICIENTS


 

(7) HYDRAULIC PUMPS AND MOTORS

MATH MODELS OF IDEAL ENERGY CONVERTERS

            SYMBOLS, IDEAL MACHINES AND PRACTICAL MACHINES

POSITIVE FLOW AND PRESSURE SOURCES

FIXED DISPLACEMENT MOTOR CHARACTERISTICS

Table 1 - PUMP AND MOTOR NOMENCLATURE

Table 2 - PUMP AND MOTOR NOMENCLATURE - SUBSCRIPTS

A LOOK INSIDE A HYDRAULIC MOTOR

SIMPLIFIED LINEARIZED HYDRAULIC PUMP

TWO PORT MODELS

INTRODUCTION TO PRIME MOVER MODELING

MORE ABOUT CASE DRAIN FLOW AND PRESSURE

LIMITATIONS IN THE LINEAR MODELS

LOW SPEED COGGING EFFECTS


(8) APPLICATION METHODS FOR PRESSURE COMPENSATED PUMPS

ABOUT PRESSURE COMPENSATED PUMPS AND

CONSTANT PRESSURE SOURCE

PRESSURE COMPENSATED PUMP AND MOTOR DATA

ABOUT CONSTANT PRESSURE AND

ALMOST CONSTANT PRESSURE SOURCES

AN ADJUSTABLE CONSTANT PRESSURE SOURCE

BLACK BOX MODEL FOR CALCULATING INPUT,

OUTPUT AND INTERNAL PERFORMANCE

SOME APPLICATION CONSIDERATIONS

RELIEF VALVE AS PRESSURE REGULATOR

PRESSURE COMPENSATED MOTORS OVERVIEW

SPEED-TORQUE CHARACTERISTICS


(9) SERVO AND PROPORTIONAL VALVE CONSTRUCTION

INTRODUCTION

BASICS OF VALVE SYMBOLOGY

Pressure Control Valves

Flow Control Valves

CONSTRUCTION DETAILS OF SOME SERVO/PROPORTIONAL VALVES


(10) VALVE TESTING AND CHARACTERISTICS

ZERO-LAPPED PROPORTIONAL VALVE

NULLING THE VALVE

ANALYZING TEST RESULTS

Flow Gain

Linearity

Pressure Gain, Port

                        Pressure Gain

Servo Valve Null Characteristics

Null Sensitivity Tests

Valve Coefficient


(11) CYLINDERS

CYLINDER CLASSIFICATIONS

POWERED AND RETURN END AREAS AND CYLINDER RATIO

MECHANICAL OUTPUT POWER

            STALL FORCE

CYLINDER DYNAMIC CONSIDERATIONS

Hydraulic Capacitance of the Double Acting Cylinder

Hydraulic Cylinder Circuits with Valve Losses

EXAMPLE PROBLEMS

CYLINDER DIMENSIONAL DATA - INCH BASED

CYLINDER DIMENSIONAL DATA - mm BASED


(12) CYLINDER LOAD HOLDING AND FORCE BALANCE


(13) VALVE CONTROL OF CYLINDER MOTION

FORCE-VELOCITY OPERATING ENVELOPE

PROPER SIZING OF THE HYDRAULIC SERVO SYSTEM

Cylinder Ratio Conundrum

SCENARIO #1 -Two Points on the Operating Envelope

                                    Situation #1 - Supply pressure is specified

Situation #2 - Cylinder area is specified

Situation #3 - Valve coefficient is specified

SCENARIO #2 - One Point on the Operating Envelope

Situation #1 - Cylinder and valve are specified

Situation #2 - Cylinder and pressure are specified

Situation #3 - Pressure and valve are specified

SCENARIO #3 - All Hydraulic Parameters are specified

Situation #1 - Solve for force

Situation #2 - Solve for velocity

OPTIMAL SIZING OF THE HYDRAULIC SYSTEM

Situation #1 - Supply pressure is specified

Situation #2 - Cylinder area is specified

Situation #3 - Valve coefficient is specified

VALVE SHOPPING

DESIGNING FOR RETRACTING CONDITIONS

MAXIMUM OVER-RUNNING LOAD WITHOUT CAVITATION

MAXIMUM PRESSURE ON THE DECELERATING END

ISSUES INVOLVING MAXIMUM ACCEL AND DECEL

            NON-SYMMETRICAL VALVES

            TABLE 1 - OPTIMAL AND SUB-OPTIMAL DESIGNS COMPARED

            UNDER IDEAL AND PRACTICAL SCENARIOS

            TEST METHOD A - EQUAL FLOWS

            TEST METHOD B - EQUAL PRESSURE DROPS

            FORWARD-TO-REVERSE SYMMETRY


(14) HYDRAULIC POWER UNIT FOR MOTION CONTROL

RETURN LINE TRANSIENT TEST

PUMP RESPONSE TEST DATA

THE PULSE WIDTH MODULATION METHOD OF PRESSURE CONTROL

ACCUMULATOR SIZE



(15) DYNAMIC SIMULATION OF A PRESSURE COMPENSATED PUMP

MODELING PUMP DYNAMIC CHARACTERISTICS

            PRELIMINARY CALCULATIONS FOR THE PUMP DYNAMIC MODEL

STATE EQUATIONS FOR THE SYSTEM

Pump Response to a Flow Step

            PUMP STEADY-STATE CHARACTERISTICS

SET UP CONDITIONS FOR THE FLYING CUT OFF SIMULATION

            CAVEAT REGARDING THE LINEAR SIMULATION

Load Flow Profile

DEMAND FLOW PROFILE SYNTHESIS

Line-By-Line Explanation of the Corner Point Profile Chart

FLOW PROFILES FOR THE SIMULATION

RESULTS OF THE DYNAMIC SIMULATION

0.045 Second Pump Simulation Data

Evaluation of Simulation Results - 0.045 Second Pump

0.225 Second Pump Simulation Data

Evaluation of Simulation Results - 0.225 Second Pump

STATISTICAL SUMMARY OF THE SIMULATION

CONCLUSIONS

ACCUMULATOR SIZING TO ACHIEVE A PRESSURE VARIATION GOAL

            INTEGRATED DEMAND FLOW

            A NOTE OF CLARIFICATION

LINEAR SIMULATION TO VERIFY THE ACCUMULATOR SIZE


(16) PHYSICS OF MOTION CONTROL AND FLOW PROFILES

THE MOTION CONTROL SYSTEM

MOTION CONTROL DEFINED

THE MATHEMATICAL APPROACH

Acceleration, velocity and position are not independent

THE GEOMETRIC APPROACH

Scenario 1 - Cycle Time, Distance and ΔT Intervals are Specified

Scenario 2 - Only Total Time and Distance Are Specified

Scenario 3 - Cycle Time and ΔX Intervals are Specified

Scenario 4 - Cycle Time, Distance and Accelerations are Specified

Other Scenarios

FLOW PROFILES

SELECTION OF ACCELERATION & DECELERATION TIME


(17) CLOSED LOOP BANDWIDTH NEEDED FOR SPECIFIED ACCURACY

MOVING NULL DIAGRAM

Consequences of the Overlapped Valve

Dead Band Compensation

Closed Loop Gain

STEAD STATE POSITIONING ERROR

TOTAL DISTURBANCE CURRENT

                        Disturbance Current Contributors Explained

Simplifying Rule of Thumb for Disturbance Current

FOLLOWING ERROR AT STEADY STATE SPEED

            FREQUENCY RESPONSE CONSIDERATIONS

HYDROMECHANICAL RESONANT FREQUENCY

HYDROMECHANICAL DAMPING RATIO

Valve Leakage Resistance

FREQUENCY SEPARATION RATIO

            Outline for Using Separation Ratio in the Servo Loop Design Process

SEPARATION RATIO GRAPH

SECOND ORDER RESPONSES

DESIGNERS' AIDS REGARDING RESONANCE AND DAMPING

ESTIMATING DAMPING RATIO, ζm, FROM FRICTION FEATURES

Table 1 - CANONICAL QUADRATIC FORMS

            FOR SECOND ORDER SYSTEMS


(18) LINEAR MODEL OF THE HYDROMECHANICAL VALVE-CONTROLLED CYLINDER SYSTEM

DISCUSSION ON LINEAR VERSUS NON-LINEAR SYSTEMS

            GENERAL COMMENTARY ON LINEARITIES AND NON-LINEARITIES

            DEVELOPING THE LINEARIZED MODEL

                        Modeling the Valve

                        Simplified servovalve Model

DERIVATION OF A TWO-SOURCE, ASYMMETRICAL LINEAR VALVE MODEL

                        Valve Leakage Resistance

                        Summary of the Linear Model

                        Symmetrical Load Valve Model

            DYNAMIC MODEL OF THE HYDROMECHANICAL SYSTEM

                        Making a Block Diagram of the Hydromechanical System

                        Sketching the State Variable Diagram

                        When There is Leakage Across The Piston


(19) COMBINING THE VALVE DYNAMIC MODEL WITH THE HYDROMECHANICAL DYNAMIC MODEL

Background

                        Valve Time Delay

            DEVELOPING A VALVE DYNAMIC MODEL

                        Simplified Approximation for Finding Valve Transfer Function

                        Rigorous Method for Finding Valve Transfer Function

                        The Transfer Function

                        Commentary on the Frequency Response For Model Synthesis

                        Scaling the Transfer Function

                        Obtain A Block Diagram from A Transfer Function

                        Combining the Valve, Amplifier And Hydromechanical Circuits

Summary of the Valve-Controlled Cylinder Electrohydraulic State Variable Diagram

                        Inputs to the Valve-Controlled Cylinder System

                        A-Matrix Elements (The algebraic quantities were defined earlier)


(20) OPTIMAL SIZING AND SPEED CONTROL OF HYDRAULIC MOTORS

            OPTIMAL SIZING

            EXAMPLE OPTIMAL DESIGN PROBLEM

            FOR MOTOR SPEED CONTROL

            CLOSED LOOP SPEED CONTROL

            SPEED GAIN OF THE ELECTROHYDRAULIC SYSTEM


(21) ELECTRICITY AND ELECTRICAL MEASUREMENTS

MOVING CHARGES AND ELECTRICAL CURRENT

VOLTAGE

Absolute zero pressure and absolute zero voltage

OHM'S LAW AND RESISTANCE

Table 1 - Standard and Preferred Resistances for

                        Carbon Based Resistors

                        Table 2 - Standard and Preferred Resistances for Carbon

                        Based Resistors - Megohm ranges

Table 3 - Resistor Color Codes for Carbon-Based resistors

Table 4 - Typical resistance values for equipment that is

                        encountered daily

            RESISTOR TYPES

            FIVE AND SIX BAND RESISTORS

            OTHER RESISTOR MARKINGS

BASIC CURRENT AND VOLTAGE RELATIONSHIPS

            AC VOLTAGE

Voltage measurement

Intrusiveness

DC current measurement

            USING THE OHMMETER

            KIRCHOFF'S LAW

            CAPACITANCE AND CAPACITORS

            CAPACITOR TYPES

            SELF-HEALING

            CAPACITOR SPECIFICATIONS

            CAPACITOR MARKINGS

            CHARGE AND ENERGY STORAGE

            ELECTRIC FIELD

            USING CAPACITORS

            INDUCTANCE

            SUMMARY OF INDUCTANCE

            TRANSFORMERS

DIODES AND RECTIFIERS



(22) COMMON ELECTRONIC DEVICES FOR ELECTROHYDRAULICS

            DIODES, RECTIFIERS, AND POWER SUPPLIES

            CONVERSION FUNCTION

            HEATING VALVES

            Reducing Supply Voltage for Electronics GU4

            VOLTAGE REGULATOR CHARACTERISTICS

CIRCUIT COMMON, GROUND AND MOTHER EARTH

AMPLIFIERS

                        A "Hydraulic Transistor" Circuit

                        Integrated Circuits and Operational Amplifiers

            PRACTICAL OPERATIONAL AMPLIFIER CIRCUITS

                        Basic Inverting Amplifier

                        Basic Non-Inverting Amplifier

                        Inverting Summing Amplifier

            ZERO, OFFSET AND BIAS

            ADJUSTABLE GAIN OP-AMP CIRCUITS

                        Variable Input Resistance

                        Variable Feedback Resistance

                        Output Potentiometer

            MAKING CONNECTIONS TO THE SERVO/PROPORTIONAL

            AMPLIFIER

ANALOG INTEGRATION AND DIFFERENTIATION

SERVO AMPLIFIER

PULSE WIDTH MODULATION

POTENTIOMETER

DEAD BAND ELIMINATOR

LIMIT ADJUSTMENTS

ASYMMETRICAL GAIN ADJUSTMENT

RAMP CONTROLS

PHASE SENSITIVE DEMODULATOR

PROPORTIONAL VALVE AMPLIFIER

4-TO-20 MILLIAMP CURRENT LOOP

IMPEDANCE MATCHING AND LOADING ERRORS

Thevenin Impedance, Output Impedance, Source Impedance

Norton's Theorem

            LOADING ERRORS

ZEROING, SCALING AND PHASING THE POSITIONAL SERVO LOOP

CHARGE AMPLIFIERS

ELECTRONIC COUNTER

NOISE CONTROL

            GENERAL RULES FOR CONTROLLING NOISE

            PARASITIC CAPACITANCE AND ELECTROSTATIC INTERFERENCE

            ELECTROSTATIC SHIELDING

            GROUND LOOPS - CAUSE AND CONTROL

            DIFFERENTIAL SIGNAL TRANSMISSION

            OPTO-ISOLATION

            ELECTROMAGNETIC INTERFERENCE

            RADIO-FREQUENCY INTERFERENCE

            ELECTROMAGNETIC COMPATIBILITY


(23)SPECIAL TOPICS ON MOBILE ELECTRICAL SYSTEMS

VEHICLE ELECTRICAL SYSTEMS

BATTERIES

CHECKING BATTERY CHARGE

BATTERY CHEMISTRY

THERMAL EFFECTS

ELECTRICAL TESTS

BATTERY DETERIORATION AND AGING

DRY-CHARGED BATTERIES

BATTERY SERVICE

MAINTENANCE-FREE BATTERIES

BATTERY SAFETY

VEHICLE GROUND CIRCUITS

ALTERNATOR AND CHARGING SYSTEMS

JOYSTICKS


(24) OVERVIEW OF ELECTROHYDRAULIC MOTION CONTROL

INTRODUCTION

ELEMENTS OF MOTION CONTROL TECHNOLOGY

BACKGROUND

CONSTANT PRESSURE SUPPLY

CONVENTIONAL HYDRAULIC CIRCUITS

EFFECTIVE MOTION CONTROL

MOTION CONTROL DEFINED

PROFILES

ACHIEVING TRUE MOTION CONTROL

MOTION CONTROLLERS

OPERATING ENVELOPE

POSITIONAL SERVOMECHANISM -- THE ULTIMATE SOLUTION

MOTION CONTROL SYSTEM DESIGN

SUMMARY CONCEPTS IN MOTION CONTROL

USING TEST DATA

DESIGN METHODOLOGY

ADVANTAGES OF MOTION CONTROL TECHNOLOGY



(25) BLOCK DIAGRAMS AND TRANSFER FUNCTIONS

BLOCK DIAGRAMS

BLOCK DIAGRAM MANIPULATION

TRANSFER FUNCTIONS

SOURCES OF TRANSFER FUNCTIONS

NATURAL FREQUENCY AND DAMPING RATIO

SOME FEATURES OF TRANSFER FUNCTIONS

HIGHER ORDER SYSTEMS USING IDAS

FREQUENCY RESPONSE GRAPH CALCULATED

FROM THE TRANSFER FUNCTION

GRAPHICAL DATA PRESENTATION

STEP RESPONSE OF SYSTEM

TRANSFER FUNCTIONS AND FREQUENCY RESPONSE

SECOND ORDER SYSTEMS

SUMMARY OF FEATURES OF TRANSFER FUNCTIONS

Table 1: Selected Laplace Transform Pairs

 

(26) INTEGRAL CONTROL AND THE POSITIONAL SERVOMECHANISM

CHARACTERISTICS OF INTEGRATORS

CHARACTERISTICS OF DIFFERENTIATORS

PROPORTIONAL, INTEGRAL AND DERIVATIVE CONTROL

FEEDFORWARD

AN EXPANSION OF THE FEEDFORWARD PROCESS

INTEGRAL CONTROL -- THE CONCEPT APPLIED

TO ELECTROHYDRAULIC SERVO SYSTEMS

INTEGRAL CONTROL AS A CONCEPT

INTEGRAL CONTROL AS A REALITY

TUNING THE PID CONTROLLER

SOME PRACTICAL ASPECTS OF INTEGRAL CONTROL

INTEGRAL CONTROL IN THE DIGITAL MOTION CONTROLLER

            SUMMARY OF INTEGRAL CONTROL


(27) DYNAMIC TESTING OF A MOTION CONTROL SYSTEM

INTRODUCTION AND PURPOSE

DESCRIPTION OF THE TESTED SYSTEM

PROFILE CONSTRUCTION

SERVO LOOP TUNING BEFORE TESTING

SYSTEM OPERATION

TEST RESULTS

TEST 1 -- SUPPLY PRESSURE VARIATIONS

TEST 1 -- ERROR

TEST 1 -- EXTENSION VS RETRACTION ERROR

MORE ABOUT THE FOLLOWING ERROR

TEST 1 -- CYLINDER PRESSURES

VELOCITY ERROR

TEST 2 RESULTS

TEST 2 -- ERROR RESPONSE

TEST 2 -- SUPPLY PRESSURE AND SPEED

TEST 2 -- CYLINDER PRESSURES

CONCLUSIONS AND RECOMMENDATIONS

EQUIPMENT LIST


(28) TORQUE CELL PROFILE TESTS

            HYDROMECHANICAL RESONANCE TEST DATA

 

DESIGN METHODOLOGY - ELECTROHYDRAULIC MOTION CONTROL


ADDITIONAL RELATED READING AND REFERENCES


NOTE: This book is very light on derivations and theory. Instead, it presents hundreds of applicable
formulas that relate to the successful application of servo and proportional valves. Theoretical
discussions are supplanted with scores of completely worked example problems in order to illustrate
how the formulas are to be used. It is a necessary reference handbook for any engineer or technician
who intends to successfully use servo and proportional valve technology. Useful as a classroom text
for applied technology.