The main objective of the course is to provide students with a core understanding of the role of control systems in industrial plants; in particular, what are the fundamental problems of control, what are the design methodologies that can be used to solve them, and what are the main trade-offs involved in the process. This will allow the students to interact successfully with control experts in their professional career.

The first part of the course covers the basics of modelling and control of simple dynamical systems. These basics are then applied to simple single-variable control applications, such as level and temperature controllers, frequency control in power systems, etc. Finally, a quick overview of the principles for the analysis and design of more complex industrial applications is given. Open-source simulation tools are thoroughly used during the course for a better understanding of the role of the presented theory in practical applications.

At the end of the course the student:

• Understands the concept of dynamical system in general, and of state-space and LTI dynamical systems in particular
• Understands the main control strategies, open-loop and closed-loop, and their strong and weak points
• Understands the concept of input-output stability
• Understands the concept of transfer function and block diagram and knows their properties
  
• Knows the structure and function of PID controllers
• Knows theorems and properties that allow to analyze the behaviour of SISO linear feedback control systems
• Is aware of the performance trade-offs in feedback control systems
• Is aware of some extensions to the basic SISO linear control theory: cascaded control, disturbance compensation, on-off control, anti-windup control, 2-d.o.f. controllers, Smith predictor, multivariable control and digital control

The student is able to:

• Derive the state-state representation of simple dynamical systems whose equations are known
• Analyze the stability of simple linear systems
• Analyze the time- and frequency-domain of simple linear systems described by their transfer functions
• Analyze the behaviour of linear systems described by block diagrams
• Analyze the behaviour of a given SISO linear feedback system
• Design PID controllers given the transfer function of the process
• Design disturbance compensators and cascaded control systems
• Use the open-source OMNotebook Modelica tool to help design and simulate simple control systems
  
• Cooperate with peers in solving non-trivial control design problems with the help of a simulation tool

1. Introduction. Basic principles of control. Open-loop and closed-loop control systems.

2. Dynamical Systems.  Analysis of linear and non-linear dynamical systems. Equilibria and their stability. Transfer function, step response, frequency response of linear systems. Block diagrams.

3. SISO controllers. Analysis and design of linear SISO systems in the frequency domain. PID controllers. On-off controllers. Applications in the field of energy systems.

4. Industrial control systems. Advanced control strategies: cascade control, Smith predictor, feed-forward compensation, two degrees-of-freedom controllers. ISA-PID controllers. Basic concepts in multivariable control systems and digital control. Applications in the field of energy systems.

Course organization

The course is organized with classroom lectures and hands-on simulation-based lab sessions.

Recommended bibliography

• K. J. Åström, R. Murray, Feedback Systems: An Introduction for Scientists and Engineers. Princeton University Press, also available online.

• P. Bolzern, R. Scattolini, N. Schiavoni, Fondamenti di Controlli Automatici, McGraw-Hill.

• Course syllabus.

Some basic understanding of ordinary differential equations is helpful. All other concepts (e.g. the transfer function) are introduced from the grounds up in the course. Basic skills in calculus are expected as in most courses at Politecnico.

The course can be successfully passed in two ways:

a)       by passing two written exams held during the course, one on parts 1-2, the other on parts 3-4, and by handing in a short simulation-based assignment after the end of the course, carried out in a small group

b)       by passing a written exam on the entire course programme during the regular examination sessions 

During the written exam, the student is asked to:

• Derive the state-state representation of simple dynamical systems whose equations are known
• Analyze the stability of simple linear systems
• Analyze the time- and frequency-domain of simple linear systems described by their transfer functions
• Analyze the behaviour of linear systems described by block diagrams
• Analyze the behaviour of a given SISO linear feedback system
• Design PID controllers given the transfer function of the process
• Design disturbance compensators and cascaded control systems

The assigment consists in the solution of a number of increasingly difficult control problems on a given system model, with the aid of a simulation tool to achieve the required system performance.