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Numerical Control Systems

 

 

       

V. Sosonkin, G. Martinov

 

Text book (in Russian)

 

ISBN 5-98704-012-4

CONTENTS

List of abbreviations............................................................................................... 10
Foreword................................................................................................................. 13
Introduction............................................................................................................ 14
Chapter 1.  Classification of NC systems................................................................. 17
    1.1. Current world level of NC architectural solutions ............................................... 17
    1.1.1. CNC and PCNC-1 systems............................................................................. 19
        1.1.2. PCNC-2 systems....................................................................................... 21
        1.1.3. PCNC-3 systems....................................................................................... 23
        1.1.4. PCNC-4 systems....................................................................................... 22
    1.2. Integration based on open control and OPC
    standard (OLE for Process Control) ........................................................................  32
        1.2.1. Notions about open control....................................................................... 32
        1.2.2. SCADA.................................................................................................... 36
        1.2.3. OPC standard........................................................................................... 38
    1.3. Integration based on STEP production
    standards   (Standard for the Exchange of Product model data)................................. 44
        1.3.1. Review of STEP production standards......................................................... 44
        1.3.2. STEP-NC.................................................................................................. 46
        1.3.3. Using EXPRESS and XML in NC interfaces................................................... 52
Chapter 2.  General principles of building NC systems........................................... 55
    2.1. Architecture of PCNC systems.......................................................................... 55
        2.1.1. New generation of NC systems.................................................................. 55
        2.1.2. Modular NC architecture at the application level.......................................... 57
        2.1.3. Open architecture of NC systems............................................................... 59
        2.1.4. Virtual model of the PC-subsystem inside NC............................................. 62
    2.2. Problem of real time in control systems............................................................ 63
        2.2.1. Way the problem is put............................................................................ 63
        2.2.2. Real time in control systems..................................................................... 64
        2.2.3. Basic notions of real-time operating systems.............................................. 64
        2.2.4. Using Windows NT in control systems........................................................ 65
        2.2.5. Strategy of dispatching based on RTX extension......................................... 66
        2.2.6. Principle of organizing and dispatching
        threads in NC software....................................................................................... 68
    2.3. Problems of cycle-logic control......................................................................... 71
        2.3.1. Classification of cycle-logic control systems................................................ 71
        2.3.2. System of notions used, when organizing
        cycle-logic control............................................................................................. 72
        2.3.3. Structure of the cycle logic control system (the client part)......................... 74
        2.3.4. Alternative structures of the project in its client part.................................. 76
        2.3.5. Work of the cycle-logic control system in its server part.............................. 78
        2.3.6. Object-oriented approach in cycle logic control........................................... 80
        2.3.7. Peculiarities of cycle-logic controlling NC machine-tools.............................. 83
    2.4. Building intra-modular communication medium................................................ 87
        2.4.1. Basic functions of communication medium................................................. 88
        2.4.2. Data requests and client-server transactions.............................................. 91
        2.4.3. Virtual structure of the object-oriented bus................................................ 95
        2.4.4. Communication medium built like open modular system............................. 97
    2.5. Principles of implementing remote NC terminals................................................ 99
        2.5.1. Remote terminal of the control system..................................................... 100
        2.5.2. Computer technologies used, when
        developing the remote terminal......................................................................... 100
        2.5.3. Java libraries used, when
        implementing applets....................................................................................... 102
        2.5.4. Software tools used, when developing the remote terminal........................ 105
        2.5.5. Specifics of NC system’s remote terminal................................................. 106
    2.6. Architectural peculiarities of  NC systems,
    supporting   ISO 14649 STEP-NC........................................................................... 107
        2.6.1. STEP-NC standard as opposed to traditional
        programming of NC machine tools..................................................................... 108
        2.6.2. EXPRESS language................................................................................. 111
        2.6.3. Processes and resources in STEP-NC........................................................ 113
        2.6.4. Mixed architecture.................................................................................. 118
Chapter 3. Control tasks....................................................................................... 121
    3.1. Geometric control task................................................................................... 121
        3.1.1. Interpreter of flow programs................................................................... 122
        3.1.2. Interpolator........................................................................................... 127
    3.2. Cycle-logic control task................................................................................. 134
        3.2.1. Formal description of logic cycles............................................................ 135
        3.2.2. Software tools, supporting visual
        programming of logic cycles............................................................................. 140
        3.2.3. Software tool, generating   ++
        codes of cycle-logic executable modules............................................................. 140
    3.3. SoftPLC used for cycle-logic control of NC machine-tools................................... 142
        3.3.1. Object-oriented approach in SoftPLC software............................................ 142
        3.3.2. SoftPLC architecture................................................................................ 143
        3.3.3. SoftPLC software..................................................................................... 147
        3.3.4. CANbus-interface.................................................................................... 151
    3.4. Terminal (HMI) control task............................................................................ 155
        3.4.1. Interpreter of operator dialog in Windows-interface................................... 155
        3.4.2. Specifics of building ISO-7 bit
        editor (inside the terminal task)....................................................................... 161
        3.4.3. High level flow-programs’ editor-debugger
        (inside the terminal task)................................................................................ 165
    3.5. Realization of the diagnostic control task........................................................ 168
        3.5.1. Notions about the diagnostic process...................................................... 168
        3.5.2. Structure of the diagnostic sub-system................................................... 169
        3.5.3. Realization of the logic analyzer ............................................................. 172
        3.5.4. Realization of oscilloscope...................................................................... 174
Chapter 4. Technologies of control-systems’
software implementation.................................................................................... 178
    4.1. Technology of object-oriented programming................................................... 178
        4.1.1. Comparison of programming technologies............................................... 179
        4.1.2. Basic notions of object-oriented approach............................................... 180
        4.1.3. Methods of choosing objects in control systems....................................... 184
        4.1.4. Structure of control-systems’ software.................................................... 185
        4.1.5. Software-tools’ support of object-oriented
        programming and G. Booch’es formal methods................................................. 186
    4.2. Specifics of object-oriented programming...................................................... 188
        4.2.1. Elements of PCNC abstract model........................................................... 189
        4.2.2. Object-oriented model of PCNC systems’ modules................................... 191
        4.2.3. Object-oriented model of imaging data................................................... 193
    4.3. Methodical aspects of building open NC systems............................................ 197
        4.3.1. Notions about open NC systems............................................................. 199
        4.3.2. PCNC as open control system................................................................. 200
        4.3.3. Building NC systems like open language processor................................... 201
        4.3.4. Standard facilities of open-architecture support....................................... 204
        4.3.5. Standard software tools supporting open architecture.............................. 208
        4.3.6. Original software tools supporting open
        architecture of NC systems............................................................................. 213
        4.3.7.   Environment of developments............................................................. 215
    4.4. Technology of component software............................................................... 217
        4.4.1. Basic notions....................................................................................... 218
        4.4.2. Servo drive controller illustrating component approach............................ 221
        4.4.3. Classification of COM-interfaces and COM-servers................................... 223
        4.4.4. Area of COM applications...................................................................... 226
        4.4.5. Software tools supporting component development................................ 227
        4.4.6. Example of   ATL COM-server................................................................ 229
Chapter 5.  NC user documents.......................................................................... 231
    5.1. Structure of programming guide.................................................................. 231
        5.1.1. Phase space of technological machine................................................... 232
        5.1.2. Raise of flow-programs’ level................................................................ 236
        5.1.3. Control system functionality reflected
        in flow program version................................................................................. 238
    5.2. NC system configuration............................................................................. 246
        5.2.1. Representation of configuration parameters in NC system....................... 246
    5.3. Methods of programming NC machine tools.................................................. 252
        5.3.1. Basic notions....................................................................................... 252
        5.3.2. Coordinate axes and coordinate systems............................................... 254
        5.3.3. Trajectories of movements (types of interpolation)................................. 263
        5.3.4. Grouping coordinate axes (G581, G580)................................................ 270
        5.3.5. Spindle control.................................................................................... 273
    5.4. Methods of implementing NC flow programs
    in accordance with the standard,   ISO 14649 STEP-NC........................................ 274
        5.4.1. XML Spy software tool.......................................................................... 275
        5.4.2. Schemas of flow programs according to
         the  STEP-NC standard................................................................................. 276
Literature........................................................................................................... 287