BMC – control stratergy

Control stratergy
|—-> Continuous control —–>P,I,D Control
|–>composite control
|                 |—> PI, PD,PID
|–>Optimality –> MPC(model predictive control),  LQG (linear quadratic gaussian control)

The point which lie on the pareto optimal curve are the points which are most optimal.

CLTF(closed loop transfer function):- Gc*Gp/(1+Gc*Gp*H)

OLTF(open loop transfer function):- Gc*Gp*H

The roots of the eqn in the numerator of a transfer function are called the zeros.

The roots of the eqn in the denominator of a transfer function are called the poles.

Total no of poles in a system is known as the order of the system.

Total no of poles lying at the origin determines the type of system. For eg:- if 2 poles value turns out to be zero, then its called a type-2 system.

Poles on the left side of the complex line can only be removed while on the right cant be because it makes the system unstable.

If any zero lies on the right side of the S-plane it is called non-minimum phase system.

If any pole lies on the right side of the S-plane then it is called unstable system.

Stability:- bounded i/p –> bounded o/p –> stable

Bounded i/p –> unbounded o/p –> not stable

unbounded i/p –> SP –> cant say ( cant comment on stability)

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

basics of measurement and control superposition

The systems need to be controled because there are disturbances that are created which deviate the system from its set point or say set parameters.

Kind of disturbances:-

1) stoichistic

2) deterministic

Control systems:- The system consisting of various componenets that are connected logically is a control system.

optimality:- Minimum input + [error--->0] = optimality (optimal control)

Transfer function:- relation between input and output.

TF :- laplace(output)/laplace(input) |initial condition zero

Superposition:-

U1 + U2 —-> control system —-> Y

for U1=0 –> Y=Y1

for U2=0 –> Y=Y2

then for a linear system Y=Y1+Y2, this is superposition theorem.

Homogenity:- if input is 0 then output is zero is the priciple of homogenity.

then a simple example based on laplace transformation was solved in the class, to find the TF(transfer function)

basics of measurement and control systems

Nothing special was taught, only an overview of Measurement and Control was given. The two things that were explained were :-

1)open loop system:- in such kind of system there is no importance of the output quality , so there is no feedback mechanism to measure the variables and control them.

INPUT——–>OUTPUT(no quality requirement)

2)closed loop system:- in such a system the importance of output quality is high and hence there is a feedback mechanism made to control the system variables to maintain the system at the set point conditions. So there are sensors to measure the variables and controllers to control or say keep the system at required state  :D

INPUT——control—->output( required quality)                                                                                                                        |________feedback____|

that was the entire classs 1 of BMC

As per suggestion of kunal , the below section is added:-

Summing point is a point that gathers the information(process variable/value) given by sensors and the set parameters to find an error in the process output, so that an feedback can be generated to control the process and obtain an output as per set parameters.

Error= Set parameter(SP) – Process variable/value (VP)