Lecture 7 - Automation and Control PDF

Automation and Control ECOR 1044 – Mechatronics 1 Introduction › Automation: – Transformation of a mechanism, device, machine, facility or process to make it automatic. – Automation or automatic control, is the use of various control systems for operating e...

Automation and Control ECOR 1044 – Mechatronics 1 Introduction › Automation: – Transformation of a mechanism, device, machine, facility or process to make it automatic. – Automation or automatic control, is the use of various control systems for operating equipment such as machinery, processes in factories, boilers and heat treating ovens, switching in telephone networks, steering and stabilization of ships, aircraft and other applications with minimal or reduced human intervention. Some processes have been completely automated. 2 Wikipedia Programmable Logic Controller (PLC) › History: – Prior to the development of the PLC, relays were used to perform logic with a schematic drawing technique called ladder logic. – Later, the ladder logic schematic technique was used as a basis for developing programming languages for modern PLCs. – The development of the PLC is one of the greatest advancements in industrial automation and used in many industrial applications. – Programmable logic controllers have been available commercially since the late 1960’s. 3 Programmable Logic Controller (PLC) 4 Programmable Logic Controller (PLC) 5 Programmable Logic Controller (PLC) 6 Programmable Logic Controller (PLC) 7 Programmable Logic Controller (PLC) 8 Programmable Logic Controller (PLC) 9 10 Supervisory Control and Data Acquisition (SCADA) 11 SCADA 12 SCADA 13 SCADA 14 15 Programmable Logic Controller (PLC) › Objective: – To bring added value to a set of raw materials to produce products of higher value (finished or intermediate products) – Requires human intervention: Machine monitoring Loading, unloading and inspecting machines Participation in the production process Adjustment and maintenance 16 Programmable Logic Controller (PLC) › Gains with automation: - Reduced costs of labor and material savings - Removal of hazardous work and safety increase - Improved product quality and performance - High productivity and quality job creation 17  Programmable Logic Controller (PLC) 18 http://www.batchcontrol.com/ Programmable Logic Controller (PLC) 19 Programmable Logic Controller (PLC) 20 Programmable Logic Controller (PLC) IEC 61131-3 standard defines five programming languages ​for PLCs: Sequential Function Chart 21 Hardware vs. Software › Hardwired technology : Desired logic/operation is obtained through a connection (cabling) of difference hardware modules (relays, electronic boards, switches, and so on). › Pros: - Reliability (often used for safety functions). › Cons: - Not flexible for future changes. 22 Hardware vs. Software › Software technology : Desired logic/operation is obtained through programming. › Pros: - Flexible for future changes. › Cons: - Not used for important safety functions. 23 Type of Protections Single (proven technology): › Position switches or forced open contacts (principle of positive mechanical action); › Manually check for periodic safety functions. The system supplier should indicate the frequency with which such tests are carried out; › Oversizing of some components (eg. Relays, contactors). Single with supervision: › In addition to some techniques mentioned above, the security system must include a self-monitoring function; › Failure detecting circuits made with contactors and relays. 24 Type of Protections Redundant: › Redundancy or duplication of critical components/functions; › Use of different technologies in redundancy; › Combining the normally open and normally closed contact interlocks; › Combining different, electrical and non-electrical systems (for example mechanical, hydraulic, pneumatic). Redundant with supervision: › In addition of a combination of different technologies as described above, a continuous supervision function might be added. 25 Programmable Logic Controller (PLC) Ladder Logic: › Before PLCs, the ladder was used to describe automation technology made by using electromagnetic relays. › It is therefore appropriate to introduce briefly electromagnetic relays. 26 Electromagnetic Relay 27 Electromagnetic Relay › Joseph Henry made the first relay in 1836. › It is made from a metal plate which is attracted to a coil when the solenoid is energized and pushed by a coil spring when de-energized. › An electrical path through the normally closed contacts (NC) is created when non-energized a second path through the normally open (NO) is created when energized. 28 Ladder Logic (relays) What is the logic of the circuit? 29 Ladder Logic (relays) 30 Ladder Logic (relays) What is the logic of the circuit? 31 Ladder Logic (relays) 32 Example 33 Timers & Counters 34 Modern Control Objective: › Control the output › Achieve robustness › Change response characteristics › Etc. 35 Types of Systems › Static System: If a system does not change with time, it is called a static system. › Dynamic System: If a system changes with time, it is called a dynamic system. 36 Static Systems 𝑦 𝑡 = 𝒉(𝑢 𝑡 ) 𝑦 𝑡 = 𝒉(𝑢1 𝑡 , 𝑢2 𝑡 , … , 𝑢𝑚 𝑡 ) 37 Dynamic Systems › A model is a simplified representation or abstraction of reality. › Reality is generally too complex to copy exactly. › Much of the complexity is actually irrelevant in problem solving. 38 Black Box Model › Consider the example of a heat radiating system: 39 Black Box Model Heat Raadiating System 35 Room Temperature in Degree Celsius (y) Valve 30 Room Temperature Temperature Position quadratic Fit (oC) 25 0 0 20 y = 0.31*x 2 + 0.046*x + 0.64 2 3 15 4 6 6 12 10 8 20 5 10 33 0 0 2 4 6 8 10 Valve Position (x) 40 White Box Model › When input and output and internal dynamics of the system is known. › One should have a complete knowledge of the system to derive a white box model. dy(t ) du(t ) d 2 y(t ) u(t) =3 − y(t) dt dt dt 2 41  Example: Spring-mass-damper system › Differential equation of system: › Differential equation of system is a second-order linear constant- coefficient. › Dynamic response of system: 42  Example: RLC circuit › Integrodifferential equation: › Dynamic response of system: › From the dynamic response these two example can be found that velocity and voltage are equivalent variables, usually called analogous variables, the systems are analogous Typical voltage response for an RLC circuit systems. 43 Applications 44 Questions? 45