Lecture – Basic Control Systems 1.1 Brief History 1.2 Steps to study a control system 1.2 Steps to study a control system 1.3 Classification of Systems 1 4 System classification 1.4 System classification 1.5 System response
Modern control systems
1
Brief history of automatic control (I) • • • • • • • • • • •
1868 First article of control ‘on governor’s’ –by Maxwell 1877 Routh stability criterien 1892 Liapunov stability condition 1895 Hurwitz stability condition 1932 Nyquist 1945 Bode 1947 Nichols 1947 Nichols 1948 Root locus 1949 Wiener optimal control research 1949 Wiener optimal control research 1955 Kalman filter and controlbility observability analysis 1956 Artificial Intelligence Modern control systems
2
Brief history of automatic control (II) Brief history of automatic control (II) 1957 Bellman optimal and adaptive control 1962 Pontryagin optimal control 1965 Fuzzy set 1972 Vidyasagar multi‐variable optimal control and 9 2 id li i bl i l l d Robust control 1981 Doyle Robust control theory • 1981 Doyle Robust control theory • 1990 Neuro‐Fuzzy • • • •
Modern control systems
3
Three eras of control Three eras of control • Classical control : 1950 before – Transfer function based methods • Time‐domain design & analysis • Frequency Frequency‐domain domain design & analysis design & analysis
• Modern control : 1950~1960 – State‐space‐based methods p • Optimal control • Adaptive control
• Post modern control : 1980 after P d l 1980 f – H∞ control – Robust control (uncertain system) Robust control (uncertain system) Modern control systems
4
Control system analysis and design y y g • Step1: Modeling – By physical laws – By identification methods
• Step2: Analysis – Stability, controllability and observability
• Step3: Control law design – Classical, modern and post‐modern control Classical modern and post modern control
Signal Classification Signal Classification •• Continuous signal Continuous signal
• Discrete signal
Modern control systems
7
System classification y • Finite‐dimensional system (lumped‐parameters system described by differential equations)
– Linear systems and nonlinear systems – Continuous time and discrete time systems – Time‐invariant and time varying systems
• Infinite‐dimensional system (distributed parameters system described by partial differential equations) t d ib d b ti l diff ti l ti )
– Power transmission line – Antennas – Heat conduction – Optical fiber etc…. Optical fiber etc…. Modern control systems
8
Some examples of linear system p y • Electrical circuits with constant values of circuit passive elements passive elements • Linear OPA circuits • Mechanical system with constant values of k,m,b M h i l t ith t t l fk b etc • Heartbeat dynamic Heartbeat dynamic • Eye movement • Commercial aircraft C i l i ft
Modern control systems
9
Linear system y A system is said to be linear in terms of the system input x(t) and the system output y(t) if it satisfies the following two properties of superposition and homogeneity. homogeneity
Superposition:
y1 (t )
x1 (t )
x1 (t ) + x2 (t )
y2 (t )
x2 (t ) y1 (t ) + y2 (t )
Homogeneity:
x1 (t )
y1 (t ) Modern control systems
ax1 (t )
ay1 ((tt ) 10
Example
x((t )
let
y (t ) = x(t ) x(t − 1)
y (t )
x(t ) = x1 (t )
y1 (t ) = x1 (t ) x1 (t − 1) let
x(t ) = ax1 (t )
y (t ) = ax1 (t )ax1 (t − 1) = a 2 x1 (t ) x1 (t − 1) = a 2 y1 (t )
y (t ) ≠ ay1 (t )
Non linear system
Modern control systems
11
example The system y is g governed by y a linear ordinary y differential equation q ((ODE))
y ′′(t ) + 2 y ′(t ) + y (t ) = x′(t ) + 3 x (t ) x(t )
Time invariance A system is said to be time invariant if a time delay or time advance of the input signal leads to an identical time shift in the output signal.
LTI System y representations p Continuous-time LTI system 1. O 1 Order-N d NO Ordinary di Diff Differential ti l equation ti 2. Transfer function (Laplace transform) 3. State equation (Finite order-1 differential equations) )
Discrete-time LTI system 1. Ordinary Difference equation 2. Transfer function (Z transform) 3. State equation (Finite order-1 difference equations)
Modern control systems
16
Continuous-time LTI system
d 2 y (t ) dy (t ) LC + RC + y (t ) = u (t ) 2 dt dt Order-2 ordinary differential equation constants
LCs 2Y ( s ) + RCsY ( s ) + Y ( s ) = U ( s ) Y (s) 1 = U ( s ) LCs 2 + RCs + 1
U (s )
Linear system y Æ initial rest
Transfer function
1 LCs 2 + RCs + 1
Modern control systems
Y (s )
17
let
x1 (t ) = y (t ) dy (t ) x2 (t ) = dt
x1 (t ) = x2 (t ) R 1 x2 (t ) = − x2 (t ) − x1 (t ) + u (t ) L LC
No. of Printed Pages : 8 BAS-020. B.TECH. IN AEROSPACE ... (i) lag compensator. (ii) lead compensator ... Displaying Basic Control Theory.pdf. Page 1 of 8.
o Newton's Method using Jacobians for two equations. o Newton-Raphson Method without Jacobians for two equations. o Generalized Newton's Method from ...
Page 3 of 4. Control Systems Lab.pdf. Control Systems Lab.pdf. Open. Extract. Open with. Sign In. Main menu. Displaying Control Systems Lab.pdf. Page 1 of 4.
Lecture 4-Principles of Environmental Control and Micro-climate .pdf. Lecture 4-Principles of Environmental Control and Micro-climate .pdf. Open. Extract.