basics of measurement and control key points

Some key  points about open loop system:

1) Very simple and easy to understand.

2) No safety guarantee.

3) No accuracy guarantee.

Some key points about closed loop system:

1) Closed loop systems are always automatic system.

2) Most of the  closed loop system is divided in two parts,first is Measurement which measure and analyses the         data of system and other is Controller which control the system it may be automatic or  self control.

some of the important terms:

 Multi-input system:       More than one input

 Multi-output system:    More than one output

  In a plant there’s a control system consisting of control component which give the response.

i/p(Excitation) -> Control component -> o/p (response/behavior)

 Unit step i/p:  in which the value of input is 1.

Key points about Transfer function:

 It gives the characteristics of the system.

 Time varying behavior can be known using laplace transformation.

 Frequency response behavior can be known using fourier system.

 EXAMPLE

U(t) (excitation) -> Control component -> y(t) (response)

For this the transfer function is

= α y(t) / α u(t)    at t=0 and y(t)=0(initial condition) (alpha=laplace of that function)

=   y(s) / u(s)

 Transfer function only defined for a linear system.

 Linear system can be defined or measured by superposition theorem, Homogeni