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Industrial Automation Spring 2019, EPFL

1 Automation Overview

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Automation (automation, Automation): 1) set of all measures aiming at replacing human work through machines


(e.g. automation is applied science)

2) the technology used for this purpose


(e.g. this company has an automation department)

Automation (automatisation, Automatisierung) 1) replacement of human work through machines


(e.g. the automatisation of the textile factory caused uproar of the workers)

2) replacement of conscious activity by reflexes


(e.g. drill of the sailors allows the automatisation of ship handling)

(Cf electricity and electrification)

Definition

Definition Overview

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Expectations

• Energy, material and time savings, quality improvement and stabilisation
• Reduction of waste, pollution control
• Compliance with regulations and laws, product tracking

• Increase availability, safety
• Fast response to market
• Connection to management and accounting
• Automation of engineering, commissioning and maintenance
• Software configuration, back-up and versioning

• Life-cycle control, maintenance support

Asset Optimisation (gestion des moyens de production)

• > Human-Machine-Interface (HMI)
• > Acquisition of large number of “process variables”, data mining

Personnel costs reduction Process Optimisation

• Simplify interfaces, assist decision

• Require data processing, displays, data base, expert systems
• > Engineering Tools

Expectations Overview

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Definition

plant: the object of automation
 F: site, usine, centrale (électricité) D: Prozess, Werk, Fabrik, Kraftwerk E: planta, fabrica, instalación All automation systems share a common structure They differ in

• the type of plant controlled,
• quantity of information,
• geographical distribution.

Industrial Automation Spring 2019, EPFL

Examples

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Cars I

critical new applications: 
 brake-by-wire, steer-by-wire (“X-by-wire”) increased safety ? extreme price squeezing ¼ of the cost is electronics, tendency increasing http://spectrum.ieee.org/green-tech/advanced-cars/this-car-runs-on-code today: 50..100 ECU (electronic control units)

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Cars II

▪ 90% of the functions of a car rely on software ▪ 40% of the costs stem from the electronics ▪ 70 computers ▪ 2000 measuring points ▪ 6 data networks ▪ 200 km wiring

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Airplanes

“avionics”:

• flight control (safe flight envelope, autopilot, “engineer”)
• flight management
• flight recording (black boxes, turbine supervision)
• diagnostics
• “fly-by-wire”

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Airbus A380 – Data network

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Manufacturing I

e.g., manufacturing motor parts for cars

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Manufacturing II


Robot extension limited to 2-3 m, frequent reprogramming for new tasks, tool changes. simple embedded computer, hierarchical control

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Flexible Automation

Numerous conveyors, robots, CNC machines, paint shops, logistics.
 Download from production management, connection to administration

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Pharmaceutical Industry

Inventory Recipe management Packaging Sampling Tracking & tracing Comply with government rules:

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Oil & Gas, petrochemicals

"upstream": from the earth to the refinery down-sea control "downstream": from the oil to derived products

special requirement: extreme, explosive environment

distribution

special requirement: high pressure, saltwater, inaccessibility explosive environment with gas. special requirement: environmental protection

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Building Automation

basics: fire, intrusion, climate, energy management HVAC = Heat, Ventilation and Cooling visitors, meeting rooms, catering,…. low price tag

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Ports

from ship planning to crane manipulation and stock control

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Water treatment

fresh and waste water treatment manage pumps, tanks, chemical composition, filters, movers, quality...
 auxiliaries: methane electricity generation

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Substations

protection (Lines, transformers, generators) very high speed response control (remote or local) to guarantee power flow, safe operation (interlocking) measurement (local and remote), electricity bill, power flow in grid

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Power plants

tasks: 
 fuel supply primary process control (steam, wind) personal, plant and neighbourhood safety monitoring environmental impact electricity generation (voltage/frequency) energy distribution (substation)
 24 / 365 availability Hydro


• river
• dams
• storage dams

Thermo

• coal
• gas
• atom

• solar

• waste

Alternative

• wind
• photo-voltaic

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Solar farms: 3000 mirrors or panels to control

Industrial Automation Spring 2019, EPFL

Automation Pyramid

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Automation as a hierarchy of services

Group control Unit control Field Sensors & actors A V Supervision Primary technology Workflow, order tracking, resources

SCADA = Supervisory Control And Data Acquisition

T Production planning, orders, purchase 1 2 3 4 Planning, Statistics, Finances 5 manufacturing execution enterprise administration

Hierarchy Overview

Control

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Details of control system hierarchy

Administration Finances, human resources, documentation, long-term planning Enterprise Set production goals, plan resources, coordinate sites, manage orders Manufacturing/Ex Manages execution, resources, workflow, quality supervision, 
 production scheduling, maintenance. Supervision Supervise production and site, execute operations, visualization,
 store process data, log operations, history (open loop control) Control Group (Area) Control: Responsible for well-defined part of plant
 (closed loop, except for intervention of an operator)


• Coordinate units

• Adjust set-points and parameters


Unit (Cell) Control: Regulation, monitoring and protection of group part
 (closed loop except for maintenance)


• Measure: Sampling, scaling, processing, calibration.

• Control: regulation, set-points and parameters

• Command: sequencing, protection and interlocking

Field data acquisition (sensors, actors), data transmission
 no processing except measurement correction and built-in protection. .

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Field level

the field level is in direct interaction with the plant's hardware (primary technology)

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Control

Group control coordinates activities


• f several unit controls

Typically hierarchical, can be peer-to-peer Note: "Distributed Control Systems" (DCS) commonly refers to a hardware and software infrastructure to perform Process Automation unit controllers

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Supervisory level: SCADA

• displays the current state of the process (visualization)

• display the alarms and events (alarm log, logbook)
• display the trends (historians) and analyse them
• display handbooks, data sheets, inventory, expert system (documentation)
• allows communication and data synchronization with other centres

(SCADA = Supervisory Control and Data Acquisition)

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Control Room From the 1950s

Coal-Fired Battersea Power Station – South London, UK – 1950s Photo: Fox Photos/Getty Images

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Control Room Example From the 1970s

Steam Generating Heavy Water Reactor – (Water Cooled Nuclear Reactor) - Dorset, UK - 1970s

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Control Room from the 90s

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Control Room From the 2010s

ISO New England Control Room

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Next?

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Data Acquisition

• Acquisition protocols depend on the system/domain

E.g. Power System Applications:

• DNP, IEC 60870-5-104, IEC 61850

E.g. Industrial Plants:

• OPC, S7, MODBUS, etc.

Many proprietary protocols that bring a specific characteristics

• E.g. robustness, real-time, security, etc.
• Acquisition can be

direct

• Usually when all equipment are on the same networks or local (e.g.

for serial communications). indirect

• Through data concentrators (e.g. Remote Terminal Unit in 


Power Substations)

• Typical when different networks are involved

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Automation as a computer network

DB, Historians, Optimizers, MES Plant Network Operator Workplaces Power Management Substation Automation LV Electrification Process
 Instrumentation Fieldbus Control Network Protection & Control Instruments IEC 61850 station bus Controller OPC Server Power generation Internet

Profinet Hart

Networks Overview

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Data quantity in plants

Data reduction and processing is necessary to operate plants information flow to the operators: ~ 5 kbit/s. human processing capacity: about 25 bit/s without computers, 200 engineers (today: 3) Electricity distribution network three times more points than in conventional power plants Nuclear Power Plant 10'000 points, comprising 8'000 binary and analog measurement points and 2'000 actuation point 1'000 micro-controllers and logic controllers Coal-fired power plant today 100 measurement and action variables (called "points") analog controllers, analog instruments

• ne central "process controller" for data monitoring and protocol.

Power Plant 30 years ago 100’000 - 10’000’000 points

Data Overview

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Response time and hierarchical level

Planning Level Execution Level Control Level Supervisory Level ms seconds hours days weeks month years ERP


(Enterprise Resource Planning)

DCS MES

(Manufacturing Execution System)

PLC

(Programmable Logic Controller) (Distributed Control System) (Supervisory Control and Data Acquisition)

SCADA

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Data Quantity & Quality and Hierarchical Level

• Closest to plan most demanding response time.
• Quantity of raw data very large.
• Processing is trivial (formerly realized in hardware)
• Under computer control, except in emergency situations, 


for maintenance or commissioning. Lower Levels Higher Levels SCADA level

• Presentation of complex data to operator
• Help to make decisions (expert system) and maintenance.
• Require knowledge database in addition to plant database
• Data reduction
• Summary information
• Complex processing and decisions (requires models)
• Timing requirements are slackened. Historical data are stored

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Complexity and Hierarchical level

MES Supervision Prozessleitung Conduite de processus Group Control Gruppenleitung Conduite de groupe Individual Control Conduite individuelle Field terrain Site usine Command level Führungsebene, étage de conduite

Complexity Reaction Speed

• Sys. d'exécution

Ausführungssystem ERP days months minutes seconds 0.1s 0.1s Einzelleitung, Feld, Anlage,

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Four distinct businesses

automation equipment (control & command) engineering & commissioning primary technology (mechanical, electrical) maintenance
 & disposal

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Assessment

Describe the levels of a hierarchical control system. What is the relationship between hierarchical level, the response time, 
 data quantity and complexity? What does SCADA stands for? What is a group control used for ? What is the role of a Manufacturing Execution System ?

Plant Categories

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Plant types

• Diverse applications, but principles are always the same.
• A few basic types of plants
• Control system hardware and software shared by most applications.
• Distinction depends on point of view, domain-specific vocabulary


and marketing.

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Control Tasks

Leiten - die Gesamtheit aller Massnahmen, die einen im Sinne festgelegter Ziele erwünschten Ablauf eines Prozesse bewirken (DIN 19222) control: el conjunto de medidas que permiten influenciar el estado de un proceso para un propósito dado Conduite: l'ensemble des mesures qui permettent d'influencer l'état d'un processus dans un but fixé. messen - steuern - regeln - leiten mesure - commande - régulation - conduite measure - command - control

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Open loop and closed loop

1 2 3 4 5

temperature temperature is imprecise, depends on ambient temperature and cooking quantity but time of heating can be modulated.

120 140 180 200 220

temperature closely controlled, requires measurement of the

• utput variable (temperature)

+

• higher/

lower temperature sensor

• pen loop:

closed loop:

• n

/off

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Open loop and closed loop

• utput

controller +

• plant

state display control variable
 (analog) set-point (solicited)
 valeur de consigne Sollwert,
 plant measurement plant state sequencer plant display

closed-loop control / regulation (régulation, Regelung) keywords: feedback, analog variables, continuous processes, "process control"

• pen-loop control / command

(commande / pilotage, Steuerung, ) keywords: sequential / combinatorial, binary variables, discrete processes,
 "batch control", "manufacturing"

• utput

error (deviation) binary process value
 (valeur mesurée,
 Istwert) measurement clock

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Traditional allocation of function of computers in control systems

• pen-loop functions

Data acquisition and pre-processing Sequential control Data transfer between plant and operator Display the plant state Logging and history recording Simulation and training closed-loop functions Protection and interlocking* Regulation Process-driven sequential control Process optimization algorithms

Interlocking*: prevent dangerous actions, such as all lights on green at a crossing (interbloquage, Verriegelung, enclavamiento)

the control system acts directly and autonomously on the plant

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Discrete and continuous plants

discrete control (binary) continuous control (analogue)

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Continuous plants

Examples: drives, ovens, chemical reactors

F(p) y x

States described by continuous (analog) variables 
 (temperature, voltage, speed,...) Input/output relation: transfer function, described by differential equations Conditions necessary for control:

• Reversible: can be brought back to previous value
• Monotone: increasing input causes output to react monotonically

Principal control task: regulation
 (maintain the state on a determined level or trajectory)

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Discrete plants

e c + ¬d 1 2 3 6 5 4 7 a b c + d e init

Examples: lifts, robots, …

Well-defined non-overlapping states, abrupt transitions caused by events Mainly reversible, but not monotone: 
 removal of stimulus does not imply previous state
 Described by Finite State Machines, Petri Nets, Flow Charts.

Principal control task: command 
 (control state transitions)

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Mixed plants

Most processes have some continuous and some discrete behavior
 Description depends on point of view. Most plants consist of discrete and of continuous processes. Example 1: Motor control of a cable-car with speed control and stop at stations All parts must de described individually. Processes can be described as continuous within a discrete state or as non-linear, continuous process. Example: Time-triggered set-point temperature for an oven Example 2: A bottle-filling line is in principle a continuous process, but each step consists of a sequence of operations

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Depends on industrial process

Automotive Manufacturing Electronics Machinery Textiles Pharmaceuticals Fine Chemical Food & Beverage Metals & Mining Water & Waste Pulp & Paper Vehicles Petrochemicals Oil & Gas Electrical Power

discrete continuous

source: ARC

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Continuous and batch processes

Continuous process (processus continus, kontinuierliche Prozesse) continuous flow of material or energy e.g. motor control, cement, glass, paper production,
 rolling mill for wires, plate or profiles,
 newspaper printing: 23 m/s, steel wire 90 m/s Main task: regulation Batch process (processus de charge (par lots), Stückgutprozesse) discrete processes with handling of individual elements e.g. Numerical Controlled machine, packing machines,
 Bottle-filling, manufacturing, pharmaceutical and chemical processes. Main task: command

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Applications

Categories "process control": continuous processes, associated with fluxes, 
 e.g. sewage water treatment, petrochemical process, cement… "batch control": semi-continuous processes, associated with individual products, e.g. fine chemicals, pharmaceutical, brewery… "manufacturing": also called “factory automation”
 discrete processes, associated with transformation of parts, e.g. automobile industry, bottle-filling, packaging

Terms used vary between industries and are not defined

• consistently. Expect to hear different terms in different contexts.

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Assessment: which answers are correct ?

• 1. open loop control is only used


when the plant can produce indefinitely
 when the plant is operated in on/off mode
 when the operator can supervise the plant

• 2. closed loop control is needed when


the plant is insufficiently known
 the plant is subject to perturbations
 the plant cannot be described by differential equations

• 3. the main task of a controller in a continuous process is:


to keep the output always at the same value
 to keep the output within a certain range
 to bring the output to a specific value in a function of time

• 4. the main task of a controller in a discrete process is:


to issue commands depending on the state
 to maintain constant speed of production
 to measure the state and present it to the operator

• 5. which of the following is a consistent plant categorization:

• pen loop – continuous – closed loop


discrete – closed loop- hybrid
 process - manufacturing- batch

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Assessment: which answers are correct ?

• 1. open loop control is only used


when the plant can produce indefinitely
 when the plant is operated in on/off mode
 when the operator can supervise the plant

• 2. closed loop control is needed when


the plant is insufficiently known
 the plant is subject to perturbations
 the plant cannot be described by differential equations

• 3. the main task of a controller in a continuous process is:


to keep the output always at the same value
 to keep the output within a certain range
 to bring the output to a specific value in a function of time

• 4. the main task of a controller in a discrete process is:


to issue commands depending on the state
 to maintain constant speed of production
 to measure the state and present it to the operator

• 5. which of the following is a consistent plant categorization:

• pen loop – continuous – closed loop


discrete – closed loop - hybrid
 process - manufacturing- batch

Automation System Architecture

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Principles

A control system is a communication system of controllers and links. Structure of control system should reflect structure of plant Ideally, each unit of the plant has its own controller, interacting with controllers of related units, mirroring physical interaction. Example: Airbus: a wing is delivered with its own computers.

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System Architecture

Conceptual model presenting

• Structure
• Relationships
• Behavior

Including

• Description of most important elements of system
• Mapping of functionality onto hardware and software components
• Description of top-level human interaction with components

Purpose:

• Support reasoning about elements, structure and behavior
• Guide for implementation

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Example: Power plant control - 1980 (!)

Control systems still look similar

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Buses and processors in industrial plants

PLC nodes (multi-processors) fieldbus (30m..2 km) Operator panel Mimic board plant (Werk, usine) P disk processor pool transducers control stations plant network (500m .. 3 km) – includes control network valve thermo-couple motor Process pictures Process Data Base Logging position backplane bus node bus workstation bus instrument bus (mimic board) sensor bus directly coupled input/

• utput
• pen network, WAN

station P P C I/O MEM I/O P P C P MEM BC station M sensor bus (0,5.. 30 m)

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Example: Production management system

transportation
 cell control manufacturing
 cell control scheduling maintenance quality control

plant network floor network

production
 planning

robot
 controller

enterprise network

milling
 machine rail-guided
 vehicle

cell

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Centralized (Hierarchical) Control Architecture

Sensors, Actors PLCs Group Control Group Control Group Control Central Computer (Mainframe)

Classical, hierarchical, centralized architecture. The central computer only monitors and forwards commands to the PLCs

plant

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plant

Decentralized Control System

engineering workstation

• perator

workstation data logger controller controller controller controller

field bus plant bus

All controllers can communicate as peers (without going through a central master), restricted only by throughput and modularity considerations.

hierarchical (vertical communication) peer-to-peer (horizontal communication)

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Assessment

1. Give a high-level description of the architecture of a washing machine 2. What is a bus and why do we have more than one kind of them in a plant? 3. Name the parts of a typical hierarchical control system, its busses and controllers 4. How does the network hierarchy relate to the plant control hierarchy? 5. What is the difference between a centralized and a decentralized control system ?
 What are the (dis)advantages of the two approaches?