Ing Ind - Inf (Mag.)(ord. 270) - BV (483) MECHANICAL ENGINEERING - INGEGNERIA MECCANICA
095837 - CONTROL AND ACTUATING DEVICES FOR MECHANICAL SYSTEMS
The great majority of mechanical systems is nowadays fitted with active control aimed at improving performance, efficiency and stability. Main objective of the course is to provide the basic elements and methods for the modelling and the analysis of mechanical systems equipped with actuators and active control. In order to reach this objective, the main issues dealt with in the course are:
modelling a mechanical system coupled with dynamic model of actuator and control logic
assessment of the stability of a uncontrolled and controlled mechanical system in time domain
classic control techniques for evaluating stability, static and dynamic performance of a controlled mechanical system
introduction to the basis of modern control
Risultati di apprendimento attesi
Knowledge and understanding.
After the exam the student:
has the knowledge on the interaction between a mechanical system and its control
knows how to represent in mathematical terms a controlled mechanical system including actuator’s dynamics, through Laplace transform, transfer function and state matrix
has the knowledge on the basic principles and methods of classic control for time domain and frequency domain approach, including standard PD and PI control, through Bode Nyquist and root locus representation, combining these three approaches.
knows the basis for the practical tuning of a PID control
understand how to model an actuator on the basis of the relevant physical laws
knows the models of the most common actuators’ types (hydraulic, electrical, pneumatic)
has the basis of modern control
Applying knowledge and understanding
After the exam the student:
can build a dynamic model of an actuator coupled with a mechanical system
is able to design a PD and PI control system, selecting the best choice and comparing the performance of the controlled system
can make the practical tuning of a PID controller
can select the most suitable actuator for a control application
is able to recognise the nature of instability problems in an uncontrolled and a controlled mechanical system
is able to describe and communicate the results of performance analysis and the control design also in graphical term
Introduction to the control of mechanical systems. Basic concepts of a dynamic system, input and output variables. Control variable and observed variables. Control of a mechanical system: feed-back and feed-forward. Effects of the control action on dynamic performance and disturbance rejection.
Stability of mechanical systems. State dependent force fields: conservative and non-conservative. Mechanical systems under the influence of force fields: general description, equations of motion and linearization, solution of the equations of motion, discussion of stability, position and velocity force fields. Fluid forces on a rigid body including aerodynamic instability (single d.o.f and flutter instability of a profile).
Classic control. Simulation models. State variables. Harmonic transfer function. Laplace and Fourier transform. Frequency response function. Block diagram representation. Root Locus. Bode and Nyquist diagram. Nyquist criterion. Requirements of a controlled dynamic LTI (linear time invariant) SISO (single input single output) system: synthesis of the control logic, definition of performance and robustness indexes.
PD and PI controller. Application to 1 dof and 2 dofs vibrating systems. Performance assessment of the controlled system in time domain and frequency domain. Input and output disturbance rejection.
Electric actuators: basic components, performances, characteristic curves. DC drives: control s. AC drives: control and power electronics, models for synchronous brushless motors. Control of electric drives: basic principles, criteria for torque and speed control, performances.
Pneumatic actuators: basic components (cylinders, valves, …), model of a controlled air spring.
PID control: practical tuning rules.
Modern approach to the synthesis of a controller. Controllability and observability of a system, Pole placement method.
Kinematics, dynamics and vibration of mechanical systems composed of rigid bodies with one and 2-n degrees of freedom.
Matrix algebra, eigenvalues eigenvector calculation, systems of ordinary linear differential equations.
Knowledge on meaning of FFT transform and frequency domain treatment of mechanical systems.
Modalità di valutazione
The exam is divided into a written test and an oral exam. A positive evaluation in the written test is mandatory for accessing the oral exam.
In the written test it is requested to model and analyse the equations of a controlled mechancial systems with actuator, at three different levels, single d.o.f mechanical system with a) simplified actuator model and b) full dynamic actuator model, c) 2 d.o.fs mechanical system. Aim of the written test is to verify the applied knowlegde and understanding of contolled mechanical system fwith regard to modelling, stability and performance anlysis, with all the tools in Laplace, frequency and time domain.
The oral exam is organised through open questions to be answered to in a written format, including comments, equations and graphical representations, about all the topics of the knowledge and understanding, as well as the capability of comunicating knowledge and results in a technical, concise and proper way.
Some PC laboratory activities will be proposed during the course on stability analysis and control with hydraulic actuators. Students can optionally write a short descriptive report, whose discussion can be part of the oral exam, on students' free request. This activity focuses on their ability in technical reporting and communicating results, as well as critical analysis of the obtained results.
mechanical systems controlBeep on lineK. Ogata, Modern Control Engineering, Editore: Prentice Hall Ed
L. Meirovitch, Dynamics and control of structures, Editore: John Wiley & Sons Ed
G. Diana, F. Cheli, Advanced dynamics of mechancial systems, Editore: Springer, Anno edizione: 2015
Merrit, Hydraulic control systems, Editore: John Wiley & Sons
A. Hughes, Electric Motors and Drives-Fundamentals, Types and Applications, Elsevier, Editore: Elsevier
Tipo Forma Didattica
Ore di attività svolte in aula
Ore di studio autonome
Laboratorio Di Progetto
Informazioni in lingua inglese a supporto dell'internazionalizzazione
Insegnamento erogato in lingua
Disponibilità di materiale didattico/slides in lingua inglese
Disponibilità di libri di testo/bibliografia in lingua inglese
Possibilità di sostenere l'esame in lingua inglese
Disponibilità di supporto didattico in lingua inglese