Process control architectures aim to maintain specified properties of process outputs at reference values. Open loop systems run without monitoring outputs, while closed loop systems automatically achieve and maintain desired outputs by comparing them to actual outputs via feedback loops. Feed forward loops anticipate future effects by measuring other variables.

1. ARCHITECTURAL STYLES - 3
Interpreters
Process Control
Other Architectures
Dr Reeja S R
Professor
CSE Dept
SJEC,Vamanjoor, Mangalore

2. INTERPRETERS
Suitable for applications in which the most appropriate
language or machine for executing the solution is not
directly available

3. Interpreter
 An interpreter takes a program written in one
language and interprets it to another language

4. Interpreter

5. Interpreter
 An interpreter has 4 Components:
 “Program” being executed and its data
 Interpretation engine and its state
 Connectors
 procedure calls and shared state.

6. Interpreter Examples
 Programming Language Compilers: Java, Smalltalk
 Rule Based Systems: Prolog, Coral
 Scripting Languages: Awk, Perl

7. PROCESS CONTROL
ARCHITECTURAL STYLE

8. Terminologies
 Process variable – measurable property in the process.
 Controlled variable – the process variable whose value, the
system has to control
 Set point – the desired value for controlled variable
 Manipulated variable - the process variable that in changed
in order to keep the controlled variable at the set point
In a water tank, if the level of water (controlled variable) is not up to
the mark (set point), then increase flow of water (manipulated
variable)

9. Process Control
The purpose of a process control system is to
maintain specified properties of outputs
(controlled variables) of the process at the
given reference values (set points)

10. Types of Process Control loops
1. Open Loop
2. Closed Loop / Feedback loop
3. Feed Forward loop

11. Open Loop Control - Process runs without
surveillance
An open-loop system is expected to faithfully follow its input
command or set point regardless of the final result

12. Open Loop Control
This is an open loop system because, system does not monitor or
measure the temperature of the output air to see if it is heated
to the desired temperature

13. Closed Loop Control
 Closed-loop systems are designed to automatically achieve and maintain
the desired output condition by comparing it with the actual condition.

14. Feedback Loop

15. Feed forward Loop
It anticipates future effects on the controlled variable by measuring other
process variables and adjusts the process based on these variables.

16. Feedback Vs Feedforward
Car's cruise-control system that maintains speed of the car even in varying
terrains
 If it has feedback control, when there is a slope and therefore a speed reduction, the
feedback controller would compensate by applying additional throttle to the engine.
 If it uses a feed-forward controller instead, the controller would calculate the slope
beforehand and throttle the engine before any speed reduction occurs. In this sense, the
controller predicts the incoming deviation and compensates for it.

17. Feed forward Loop
It anticipates future effects on the controlled variable by measuring other
process variables and adjusts the process based on these variables.

18. Other Familiar architectures
 Distributed processes

19. Other Familiar architectures
 Main Program/ Sub-routine
 Centralized control, sequential execution in some order

20. Other Familiar architectures
 Domain specific architectures
 Organizational structure tailored for a family of
applications such as avionics, command and control,
vehicle-management, etc

21. Other Familiar architectures
 State transition systems
 Applicable for Reactive systems