Post by ZeroVash on May 5, 2013 17:42:25 GMT -5
So ... I am back again. Kinda got in the mood to write again, and i figured i might as well do some more work and share it here 
At this time i decided to cover a basic introduction to automatic control systems. (Attention: This won't in no way possible or imaginable replace your control lectures. This will just be a basic run over this particular topic which interests me. I'll be mainly supporting this threads with my own knowledge and Ogatas' book which i recommend for people who want to delve deeper into the subject)
Control theories are commonly used today in any engineering branch. Anything that involves controlling something like temperature, pressure, humidity, space shuttles, robotics systems, etc.. It is therefore important for each engineer to have a solid knowledge of this particular subject.
Basic Definitions:
-> Controlled Variable and Control Signal: The Controlled Variable is the 'thing' we want to control (Duh!) while the Control Signal (also called the manipulated variable) is the 'thing' we can change to affect the controlled variable. In other terms, Controlled Variable is our output, while the Control Signal is our input.
-> Plant: A plant can be part of an equipment, or just a set of components that work together with a purpose. For example any sort of object that can be controlled (like an oven, a chemical reactor, a space shuttle, etc..).
-> Process: A process is every operation that involves the control of something. For example chemical processes, biological processes, etc..
-> Systems: A system is basically a combination of components that act together to achieve a goal.
-> Disorders: A disorder is a signal that tends to oppose the general way the output of the system is supposed to be. If a disorder is created inside the system it will be called internal disorder, while the external disorder is created outside the system and acts like an input signal.
-> Control with Feedback: Feedback is an operation that in the presence of disorders tends to diminish the difference between the output of a system, and its input reference acting according to that difference.
Some quick examples:
-1) Speed Control: The basic principle of a Watt speed regulator for a motor is based on: "The fuel quantity supplied to the engine is adjusted by analyzing the difference between the expected speed and the engine effective speed .
-2) Temperature Control: By measuring the current temperature, the system can compare it to its reference value (set by a human operator) and let the system act according to that result.
Closed Loop vs Open Loop:
Any system that establishes a comparison between the output of the system and its reference input, using the difference as the key to its control (reducing the following error) its usually called a closed loop system or a feedback loop system.
The other side of the coin, the open loop systems, are the ones where the systems output does not exert any action in the system. That means that in that case the output is not measured or compared with the entrance reference. A practical example is for example: The Washing Machine. There are several steps to it and they're followed in order, but the system doesn't check for example if the clothes are well washed. In the presence of disorders, an open loop system wont perform as desired. All systems that work trough timed sequences are open loop systems.
So, one of the big closed loop systems advantage is that feedback makes the systems' response less vulnerable to disorders and internal parameters changes. However stability wise, closed loop systems require a great deal of tuning while open loops don't.
So this is it for today.. I figured a nice clean introduction on control would get you guys hyped. Am i right or am i right?
Leave your questions/feedback(ehehe pun?!) below If you actually made it this far share some thoughts ^_^ I'll gladly read and reply 
Till' next time.
At this time i decided to cover a basic introduction to automatic control systems. (Attention: This won't in no way possible or imaginable replace your control lectures. This will just be a basic run over this particular topic which interests me. I'll be mainly supporting this threads with my own knowledge and Ogatas' book which i recommend for people who want to delve deeper into the subject)
Control theories are commonly used today in any engineering branch. Anything that involves controlling something like temperature, pressure, humidity, space shuttles, robotics systems, etc.. It is therefore important for each engineer to have a solid knowledge of this particular subject.
Basic Definitions:
-> Controlled Variable and Control Signal: The Controlled Variable is the 'thing' we want to control (Duh!) while the Control Signal (also called the manipulated variable) is the 'thing' we can change to affect the controlled variable. In other terms, Controlled Variable is our output, while the Control Signal is our input.
-> Plant: A plant can be part of an equipment, or just a set of components that work together with a purpose. For example any sort of object that can be controlled (like an oven, a chemical reactor, a space shuttle, etc..).
-> Process: A process is every operation that involves the control of something. For example chemical processes, biological processes, etc..
-> Systems: A system is basically a combination of components that act together to achieve a goal.
-> Disorders: A disorder is a signal that tends to oppose the general way the output of the system is supposed to be. If a disorder is created inside the system it will be called internal disorder, while the external disorder is created outside the system and acts like an input signal.
-> Control with Feedback: Feedback is an operation that in the presence of disorders tends to diminish the difference between the output of a system, and its input reference acting according to that difference.
Some quick examples:
-1) Speed Control: The basic principle of a Watt speed regulator for a motor is based on: "The fuel quantity supplied to the engine is adjusted by analyzing the difference between the expected speed and the engine effective speed .
-2) Temperature Control: By measuring the current temperature, the system can compare it to its reference value (set by a human operator) and let the system act according to that result.
Closed Loop vs Open Loop:
Any system that establishes a comparison between the output of the system and its reference input, using the difference as the key to its control (reducing the following error) its usually called a closed loop system or a feedback loop system.
The other side of the coin, the open loop systems, are the ones where the systems output does not exert any action in the system. That means that in that case the output is not measured or compared with the entrance reference. A practical example is for example: The Washing Machine. There are several steps to it and they're followed in order, but the system doesn't check for example if the clothes are well washed. In the presence of disorders, an open loop system wont perform as desired. All systems that work trough timed sequences are open loop systems.
So, one of the big closed loop systems advantage is that feedback makes the systems' response less vulnerable to disorders and internal parameters changes. However stability wise, closed loop systems require a great deal of tuning while open loops don't.
So this is it for today.. I figured a nice clean introduction on control would get you guys hyped. Am i right or am i right?
Leave your questions/feedback(ehehe pun?!) below
If you actually made it this far share some thoughts ^_^ I'll gladly read and reply 
Till' next time.
But feel free to ask. Whatever my knowledge falls short on i'm sure Ogata has the answer 