Fundamentals of Control Systems (First module)
Ingegneria Informatica e dell'Automazione (A-K) A.A. 2017/2018
Course Outline
First Part
- Basic concepts: an introduction to feedback control. Definitions of system, signals, inputs and outputs. Control system goals. Inputs and disturbances. The reference signal. The error signal. Control and regulation. Introduction to basic control techniques: open-loop and closed-loop control. Examples. The basic components of a feedback control system: input filter, controller, actuator, sensor and plant. Examples.
- Modelling of dynamic systems: Mathematical models taxonomy. Static systems, dynamic systems. Causality. Linear and non-linear systems. Time-variant and time-invariant systems. Mathematical models of basic systems: mechanic systems (mass-spring damper model, quarter car), electrical systems, water tank systems, thermal systems. Linearization of a non-linear system around the equilibrium (water tank system example). Linear time invariant systems (LTI): linear differential equations with constant coefficients. Solution of linear differential equations with constant coefficients: free evolution and forced response. The initial conditions problem.
- Laplace Transform: Test signals: step, ramp, parabolic ramp, Dirac delta (impulse), finite duration impulse, sinusoid. Laplace transform, properties and theorems. Convolution integral. Anti-transformation techniques. L-transform to find the complete response of an LTI system.
- Basic block diagrams reduction techniques: Basic block interconnections: series, parallel, feedback. Moving summing junctions. Moving branch points. Examples.
- Examples of LTI systems modelling. Electrical networks: integrator, derivative, lead, lag, lead-lag. Speed control of DC electric motor.
- Analysis in the complex variable domain. Free evolution and the initial value problem. The forced response and the transfer function. The pole-zero map and the impulse response time evolution. First-order and second-order systems: forced response to impulse, step and ramp. Influence of a zero on the step response of a first order and second order system. Transient response specifications: delay time, rise time, settling-time, peak time, maximum overshoot.
Second Part
- Stability analysis. Lyapunov definition of equilibrium stability. Definitions and fundamental theorems of stability for LTI systems. BIBO stability. Routh Lemma (necessary condition) and Routh-Hurwitz criterion. Special cases in the construction of the Routh table. Examples.
- Properties of closed-loop systems. Steady state error in unitary-feedback control systems. Error coefficients (position, velocity, acceleration). The generalization to the non-unitary feedback control systems. Disturbance rejection in open-loop and closed-loop systems. Feed-forward compensation. Sensitivity to parametric variations in the transfer function of the forward branch and feedback branch. The sensitivity function.
- Root locus. Root locus and complementary root locus. General rules to construct the root loci. Root locus for control system design (basic concepts). Examples.
Suggested Books
- P. Bolzern, R. Scattolini, N. Schiavone, "Fondamenti di Controlli Automatici", McGraw Hill, Seconda Edizione, 2004
- G.F. Franklin, J. D. Powell, A. E. Naeini, "Feedback Control of Dynamic Systems", ISBN 978-0131499300, Fifth Edition, Prentice Hall, 2005