Control System Engineering- Overview Antenna Positioning Control System Control System Engineering- Overview Need for understanding physical significance of every word we learn in engineering nothing should be accepted blindly! Physical significance of simple terms like voltage & current, time domain & frequency domain, Introduction to the field Control System Engineering High-level Systems Definition Overview of Open Loop and Closed Loop Systems Design Approach High-level introduction to Matlab Control System Engineering- Overview Antenna Positioning Control System Physical Significance - Reviewed Why Voltmeter should have high impedance &Ammeters should have low impedance Why a voltage amplifier should high i/p & low o/p impedances What is the difference between analog & digital signals? Historical Background The important milestones in the field of control theory 1788 : James Watt - Flyball governor for speed control of prime movers 1800 : Laplace - Laplace transforms 1868 : Maxwell - Flyball stability 1877 : Routh - Stability 1890 : Liapunov - Non-linear stability 1932 : Nyquist - Nyquist stability criterion Classical Control 1938 : Bode - Frequency response methods 1948 : Evans - Root-locus 1960 : Kalman - Optimal estimation state-space methods the beginning of modern control concepts Late 1970s - Beginning of Robust control Control System Engineering - Overview Systems Finally Control System Engineering - Overview Become a Control Engineer Control Engineer Even a student can be considered as a system Control System Engineering - Overview Control System Engineering Overview Inputs Outputs So, what is the message ? Processing Tasks (achieved by any means could be by mechanical, electrical Electronics, meta-physical means) A System Has Essentially, we could think of system to be anything - no limits! Could be Social System Financial System Education System Or Planetary System Space System Or Mechanical System Electrical System Electronic System Or .. Could be Social System Financial System Education System Or Planetary System Space System Or Mechanical System Electrical System Electronic System Or .. Control System Engineering - Overview However as a control engineer you will be more focusing on mechatronics systems So, lets take an example of a mechatronics system. Inputs ? Outputs? Can process commands Acceleration Command Direction Command Speed Direction Control System Engineering - Overview How do you see a car as a system? So, a car is an interconnected system of sub-systems of sub-sub systems of sub-sub-sub till we end up into smallest indivisible sub-systems (say piston) That can perform a desired task! Inputs ? Outputs? Engine System Steering System Entertainment systems Comfort systems Safety systems Etc . CAR System Control System Engineering - Overview SO HOW ARE SYSTEMS CLASSIFIED ? SYSTEMS OPEN LOOP CLOSED LOOP Control System Engineering - Overview What are the Open-loop systems ? Can they meet the desired objectives of an intended system? Are they reliable or dependable ? Are the all practical open-loop systems stable ? Are there any practical open-loop systems ? Open-loop Systems Discussion Any good examples ? Control System Engineering - Overview So, Are there any Open-loop Systems Unstable? How are they made stable? So, Are there any Open-loop Systems Unstable? How are they made stable? Control System Engineering - Overview Bicycle man in the loop Motorbike man in the loop Fighter plane - autopilot Top angular momentum Open-loop Unstable Systems how they are made stable Man in the loop? Control System Engineering - Overview So essentially Open-loop Systems could be stable or unstable? Some times the design requires that open-loop systems have to be unstable Between stable & unstable states is there any intermediate state of a system? So essentially Open-loop Systems could be stable or unstable? Some times the design requires that open-loop systems have to be unstable Between stable & unstable states is there any intermediate state of a system? Control System Engineering - Overview Open-loop Systems could be marginally stable Open-loop Systems could be marginally stable Hey it is stable!! But any small wind can Kick this out of balance! Control System Engineering - Overview Nothing is perfect on this earth! But nothing is impossible also Same with any open-loop systems They may meet your expectation today but fail tomorrow So, the summary is They may be stable today, unstable tomorrow They could be safe today, unsafe tomorrow This is the engineering challenge. An engineer is always challenged by reliable & cost effective solutions! Control System Engineering Overview It is possible to overcome the limitations of open-loop systems with the application of Feedback Technology which brought close-loop systems into existence The closed-loop systems can be designed to achieve cost effective solutions with near perfection! Hey Guys! Dont you worry if u r not perfect! No more open- loop Apply feedback technology in your practical life To achieve perfection and pass out with flying colors! Control System Engineering Overview Closed-loop systems work on feedback technology Can meet the desired objectives of an intended system Very reliable or dependable can accommodate system uncertainties to some extent! All closed-loop systems are designed to be stable & safe All most every mechatronics system exists today work in closed loop Closed-loop Systems It is closed-loop systems that offer cost effective solutions Control System Engineering Overview Closed-loop Systems depend on Feedback sensors Provides the excitation for the plant Controls the overall system behavior, the design objective of a control engineer A system/plant to be controlled (Problem at hand) Tacho & Road Markings Tacho & Road Markings Sensor depends on the Output variable Controller Plant Sensor Control System Engineering - Overview 1. The Controller implements control laws 2. It could be a simple gain using an opamp or 3. Dedicated computer implementing complex control laws 4. The development of control laws involves plant modeling, simulation & analysis Sensor So the greater challenge lies in the controller design Why modeling? Plant is there na! The design challenges Availability of suitable sensors Modeling Expertise Stability issues Non-linearity issues Sensor Feedback Role Reduce error Enhance robustness Disturbance rejection or elimination Improve dynamic performance Control System Engineering - Overview 1. Selection of suitable sensors 2. Design control laws Sensor So what is your task as a control engineer? Selection of sensor depends on the output variable to be controlled & underlying Technology of the sensors which may call for additional software processing Selection of sensor depends on the output variable to be controlled & underlying Technology of the sensors which may call for additional software processing Control System Engineering - Overview Summary Open Vs. Closed Loop Systems OPEN LOOP Simple Design Accuracy dependant on calibration Unlikely to become unstable Closed Loop More accurate Less sensitive to changes in environment Smooth response Can become unstable (needs adequate safety margins) Controllers Case Study 1. The Control law depends on the problem at hand 2. If the plant needs a minor improvement a simple gain can provide a solution! 3. If the plant is complex and requires a very high performance then the control laws could be very complex as well. 4. The most famous control law that finds place in process control industry is a PID control. 5. The PID controller provides required improvement in the system performance Sensor How am I going to decide a control law? PID? I thought this guy is going to make things simpler but Making complicated by Bringing new terms! Control System Engineering - Overview What is a PID Controller ? Sensor PID PID Controllers Error input Mr. Proportional (Kp) Mr. Differentiator(Kd) Mr. Integral (Ki) Plant drive Control System Engineering - Overview What these guys Kp, Ki, Kd can do? Mr. Proportional can reduce the rise time but never can eliminate the steady-state error. Mr. Integral can eliminate the steady-state error but makes the transient response worse. Mr. Derivative can increase the stability of the system, reduce the overshoot, and improve the transient response. Control System Engineering - Overview WoW! Teamwork Plays! Each has their own strengths & weaknesses but as a team they have only the strength! Summary of Kp, Kd, and Ki influence on a closed-loop system. CL Response Rise TimeOvershootSettling Time Steady State Error KpDecreaseIncreaseSmall ChangeDecrease KiDecreaseIncrease Eliminate Kd Small Change Decrease Small Change Summary of Kp, Kd, and Ki Capabilities Control System Engineering - Overview Simply Great! Lets Put the things together! The e represents the tracking error R-Y The e will be sent to the PID controller which computes both the derivative and the integral of e The u as per control law generated. The u will be sent to the plant, and the new output Y obtained This new output Y sent back to the sensor again to find the new e The controller takes this new error signal and computes its derivative and integral again. This process goes on and on and on Sensor PID This is how PID works Control System Design by Example Problem statement Plant F x Standard problem - simple mass, spring, and damper problem. Math model (equation) : Laplace Transfer : Transfer Function : The design goal Fast rise time Minimum overshoot No steady-state error Use PID controller The design goal Fast rise time Minimum overshoot No steady-state error Use PID controller Let M = 1kg b = 10 N.s/m k = 20 N/m F(s) = 1 Putting some numbers Step 1 : Open-loop Response Analysis What is the step response? What is the SS gain? Oops! What the hell! Response is too slow! Too high steady state error! What did we observe? The DC gain is 1/20, so 0.05 is the final value of the output to an unit step input. This corresponds to the steady-state error of 0.95, quite large indeed. The rise time is about one second and the settling time is about 1.5 seconds. What have we to do? Step 1 : Open-loop Response Analysis What is the step response? What is the SS gain? Oops! What the hell! Response is too slow! Too high steady state error! What did we observe? The DC gain is 1/20, so 0.05 is the final value of the output to an unit step input. This corresponds to the steady-state error of 0.95, quite large indeed. The rise time is about one second and the settling time is about 1.5 seconds. Design a controller that will reduce the rise time the settling time and eliminates the steady-state error. A PID could be tried Step 2 : Lets take help of Mr. Proportional What Kp can do? If Kp = 300 What is the SS gain? Transfer Function with Kp : Watch the step response now! Step 2 : Lets take help of Mr. Proportional What Kp can do? Hey! Kp reduced rise time and the steady-state error. Oops! Increased the overshoot, and decreased the settling time! Chalega! It is not so worse, very small. Step 3 : Lets take help of Mr. Derivative now! What Kd can do? If Kp = 300 What is the SS gain? Transfer Function with Kp and Kd : Watch the step response now if Kd = 10! Fantastic Yaar!! Overshoot below 1.2! & settling time amazing !!! Great Kp & Kd ! Looks v r done! No No! rise time & steady state error thoda teak karma hein! We will select PID controller for this problem 2. The transfer function of the PID controller 1. The PID control law Sensor PID Tracking Enemy Target Tracking Element Line-of-Sight Tracking Line Error Programmable Logic Controller - Overview Historical Background 1969 : Dick Morley 1973 : Michael Greenberg - First commercial successful PLC Programmable Logic Controller - Overview What is PLC ? PLC Block Diagram PLC is an industrial computer control system that continuously monitors the state of input devices and makes decisions based upon a custom program, to control the state of devices connected as outputs. Programmable Logic Controller - Overview Inside PLC The CPU contains an Executive program that tells the PLC how to Execute the control Instruction - Users Program Communicate with other devices - Other PLCs, Programming devices, I/O devices, etc. Perform Housekeeping activities - Diagnostics, etc. This program is stored in non-volatile memory Meaning that the program will not be lost if power is removed What are the Inputs? Switches and Push buttons Sensing Devices - Limit Switches - Photoelectric Sensors - Proximity Sensors Condition Sensors - Pressure Switches - Level Switches - Temperature Switches - Vacuum Switches - Float Switches Encoders Programmable Logic Controller - Overview What are the Outputs? Valves Motor Starters Solenoids Actuators Control Relays Horns & Alarms Stack Lights Fans Counter/Totalizer Pumps Printers Programmable Logic Controller - Overview PLC Operating Cycle Four Steps in the PLC Operations Input Scan Scan the state of the Inputs Program Scan Processes the program logic Output Scan Energize/de-energize the outputs Housekeeping This step includes communications, Internal Diagnostics, etc. The steps are continually repeated - processed in a loop Programmable Logic Controller - Overview Programming the PLC Ladder Logic (LL) IEC Format Function Block Diagram (FBD) Structured Text (ST) Instruction List (IL) Ladder Diagram (LD) Sequential Function Chart (SFC) - also known as Grafcet Programmable Logic Controller - Overview Anatomy of a Ladder Program Programmable Logic Controller - Overview Ladder Logic - Logical AND Programmable Logic Controller - Overview Ladder Logic - Logical OR Communications Protocols A set of rules for data exchange (format and timing of data) in a communications system Stack / profile = selected set of protocols for a communication application Communication Relationships Master / Slave - request / response & response only Peer-to-Peer - client / server, publisher / subscriber Communication Architectures Star (point-to-point) Bus, Ring, LAN (multidrop) Programmable Logic Controller - Overview Communication Protocols Ethernet Modbus Plus Modbus S908 LonWorks Interbus Profi-bus DeviceNet Uni-Telway Programmable Logic Controller - Overview CAN-Open ASi Seriplex FIPIO/FIPway RIO HART DIO ControlNet ASCII PLC Advantages: Flexibility Implementing Changes and Correcting Errors Low Cost Piolt Running Visual Observation Reliability and Maintainability PLC Disadvantages: Fixed Program Applications Fail-Safe Operation Programmable Logic Controller - Overview PLC Applications: Automotive Manufacturing Industry Hospitals Food Industry Aerospace Travel Industry Printing Industry Plastic Industry Agriculture Film Industry Textile Industry PLC Vendors Siemens Allen- Bradley Mitsubishi Omron Schneider Programmable Logic Controller - Overview EVOLUTION Distributed Control System - Overview Manual Control DCS Distributed Control system Pneumatic Control (local) Pneumatic Regulation (centralised) Analog Electronics DAS Data Acquisition System Distributed Control System - Overview What is DCS? DCS is a computerized control system used to control the production line in the industry. Why DCS System is required? More efficient operation Greater process reliability Better control of critical phases of process Better visibility of process information Graphic representation of data Electronic acquisition of data Self and detailed diagnostic function of the control systems DCS ARCHITECTURE Distributed Control System - Overview Instrumentation / Valves Contol Level Supervisiory Level Management Informations Process Production Instrumentation Equipment LIMITS OF OLD DCS Technologies in perpetual evolution Proprietary control network Field Instrument isolated from the control Control systems are mainly limited to control process INTELLIGENCE OF THE FIELD Distributed Control System - Overview PV Site Control Room This information remain on the field unexploited in our units. Informations Distributed Control System - Overview MODERN CONTROL SYSTEMS & ARCHITECTURE Integration Exploitation of capacities Field-based architecture Open architecture & industry standards International standard Manage process, devices Scalable BENEFITS Reduced maintenance costs and implementation of predictive maintenance strategies. Better informend about the status and condition of plant instrumentation Automated documentation. Separate information relevant to the operator from that relevant to the maintenance personnel. Improves daily instrumentation maintenance activities. Better use of maintenance ressources. Distributed Control System - Overview DCS Applications Electrical power grids and electrical generation plants Environmental control systems Radio signals Water management systems Oil refining plants Metallurgical process plant Chemical plants Sensor networks Pharmaceutical manufacturing Distributed Control System - Overview DCS Vendors Yokogawa CS 3000 Moore APACS Honeywell GUS ABB Freelance 2000 Fox boro I/A series Fisher Rosemant RS3 Siemens Emerson Baily Invensys Distributed Control System - Overview What is SCADA? Supervisory Operator/s, engineer/s, supervisor/s, etc Control Monitoring Limited Telemetry Remote/Local Data Acquisition Access and acquire information or data from the equipment Sends it to different sites through telemetry Analog / Digital Supervisory Control and Data Acquisition - Overview Why SCADA? Saves Time and Money Less traveling for workers Reduces man-power needs Increases production efficiency of a company Cost effective for power systems Saves energy Reliable Supervisory control over a particular system Supervisory Control and Data Acquisition - Overview SCADA Architectures SCADA systems have evolved through 3 generations Basic SCADA One machine process One RTU and MTU Distributed SCADA Multiple RTUs DCS Networked SCADA Multiple SCADA Supervisory Control and Data Acquisition - Overview Basic SCADA Supervisory Control and Data Acquisition - Overview Car manufacturing robot Room temperature control Distributed SCADA Supervisory Control and Data Acquisition - Overview Water systems Subway systems Security systems Network SCADA Supervisory Control and Data Acquisition - Overview Power systems Communication systems Supervisory Control and Data Acquisition - Overview Elements of a SCADA system Sensors and actuators RTUs/PLCs Communication MTU Front End Processor SCADA server Historical/Redundant/Safety Server HMI computer HMI software Supervisory Control and Data Acquisition - Overview Gas control system Supervisory Control and Data Acquisition - Overview Water control system Supervisory Control and Data Acquisition - Overview Power system SCADA Benefits Standard frame for application Rich functionality ( p-yrs investment) Reliability and Robustness (very large installed base, mission critical processes) Limited specific development Technical support and maintenance .. Etc Supervisory Control and Data Acquisition - Overview SCADA Applications Water and Waste water Power systems Oil and Gas Research facilities Transportation Security systems Siren systems Irrigation Communication control Supervisory Control and Data Acquisition - Overview SCADA Vendors SCADA system manufacturers Modular SCADA, UK MOSCAD, Motorola Rockwell Automation ABCO ABB Lantronix SCADA Hardware manufacturers Rockwell Allen Bradley General Electric (GE) Emerson Schneider Electric Supervisory Control and Data Acquisition - Overview SCADA Software manufacturers Intellution (Fix 32) Iconics (Genesis32 v7.0) Wonderware (InTouch) Citect (CitectSCADA 5.42) National Instruments (Lookout SCADA) SCADA security issues Is there have been any hacks into SCADA system? Data can be hacked from PC's and Networks Data can be hacked from RTU's or Remote sites Supervisory Control and Data Acquisition - Overview LAN, WAN, Modem, Internet/ RTUs at Sites Network: Visibility outside of your secured area Control Room PCs General Recommendations beyond those in the Cyber Security Review Configure/maintain/update all security features - e.g. passwords Use authentication wherever available. Use encryption wherever available (FIPS is recommended) e.g. Ethernet, especially wireless nets. Use Virtual Private Networks (VPNs) rather than, Internet, dial- up for remote communication. Supervisory Control and Data Acquisition - Overview Questions?