- •Introduction to control Part I
- •Text 1. Control System
- •8. Make a list of terms from Text 1 referring to control and memorize them.
- •9. Read and translate Text 2 Text 2. Basic Feedback Loop
- •10. Make a list of terms from Text 2 referring to control and memorize them.
- •11. Read and give a short summary of Text 3 Text 3. An example
- •12. Make a list of terms from Text 3 referring to control and memorize them.
- •13. Translate Text 4 in written form: Text 4. Regulators and Servomechanisms
- •16. Supply synonyms for the following words:
- •17. Analyse the grammatical structure of the following sentences and translate them:
- •Text 5. Stability and performance
- •19. Make a list of terms from Text 5 referring to control and memorize them.
- •23. Supply synonyms for the following words: Meet, to take place, because of, as regards, breakdown, to consider
- •24. Analyse the grammatical structure of the following sentences and translate them:
- •25. Translate Text 6: Text 6. The uncertainties
- •25. Make a list of terms from Text 6 referring to control and memorize them.
- •26. Read and translate Text 7. Text 7
- •27. Make a list of terms from Text 7 referring to control and memorize them.
- •28. Read and translate Text 8 without a dictionary. Text 8. Representations of Uncertainty
- •30. Give derivatives of the following words and translate them into Russian:
- •32. Supply synonyms for the following words:
- •Text 9. Servomechanism
- •Text 10. Performance: Tracking and Disturbance Rejection
- •43. Make a list of terms from Text 10 and memorize them. Rart II
- •1. Read and translate Text 11.
- •Text 11. The Philosophy of Classical Control
- •Make a list of terms from Text 11 and memorize them.
- •Read and translate Text 12. Text 12. Classical control theory: the closed-loop controller
- •Make a list of terms from Text 12 and memorize them.
- •Read and translate Text 13. Text 13. Controllability and Observability
- •Make a list of terms from Text 13 and memorize them.
- •Read and translate Text 14. Text 14. Control Specifications
- •Make a list of terms from Text 14 and memorize them.
- •Read and translate Text 15. Text 15. Model Identification and Robustness
- •System identification
- •Analysis
- •Constraints
- •Make a list of terms from Text 15 and memorize them.
- •Read and translate Text 16 Text 16. Control Objectives
- •Make a list of terms from Text 16 and memorize them
- •Give a short summary of Text 17 Text 17. Control Objectives
- •(From Ch.Schmid. Course on Dynamics of multidisplicinary and controlled Systems )
- •Make a list of terms from Text 17 and memorize them
- •Give a short summary of Text 18 (in written form) Text 18. Main control strategies
- •Pid controllers
- •Optimal control
- •Adaptive control
- •Intelligent control
- •17. Make a list of scientific terms that are used in Text 18, give their Russian equivalents and memorize them.
- •18. Give a short summary of Text 19 (in written form) Text 19. Feedback
- •Application of feedback in mechanical engineering
- •Make a list of terms from Text 19 and memorize them.
- •Give a short summary of Text 20 Text 20. Pid controller
17. Make a list of scientific terms that are used in Text 18, give their Russian equivalents and memorize them.
18. Give a short summary of Text 19 (in written form) Text 19. Feedback
Feedback is both a mechanism, process and signal that is looped back to control a system within itself. This loop is called the feedback loop. A control system usually has input and output to the system; when the output of the system is fed back into the system as part of its input, it is called the "feedback."
Feedback and regulation are self related. The negative feedback helps to maintain stability in a system in spite of external changes. It is related to homeostasis. Positive feedback amplifies possibilities of divergences (evolution, change of goals); it is the condition to change, evolution, growth; it gives the system the ability to access new points of equilibrium.
For example, in an organism, most positive feedback provide for fast autoexcitation of elements of endocrine and nervous systems (in particular, in stress responses conditions) and play a key role in regulation of morphogenesis, growth, and development of organs, all processes which are in essence a rapid escape from the initial state. Homeostasis is especially visible in the nervous and endocrine systems when considered at organism level.
Types of feedback are:
negative feedback: which tends to reduce output (but in amplifiers, stabilizes and linearizes operation),
positive feedback: which tends to increase output, or
bipolar feedback: which can either increase or decrease output.
Systems which include feedback are prone to hunting, which is oscillation of output resulting from improperly tuned inputs of first positive then negative feedback. Audio feedback typifies this form of oscillation.
Bipolar feedback is present in many natural and human systems. Feedback is usually bipolar—that is, positive and negative—in natural environments, which, in their diversity, furnish synergic and antagonistic responses to the output of any system.
Application of feedback in electronic engineering.
The processing and control of feedback is engineered into many electronic devices and may also be embedded in other technologies.
The most common general-purpose controller is a proportional-integral-derivative (PID) controller. Each term of the PID controller copes with time. The proportional term handles the present state of the system, the integral term handles its past, and the derivative or slope term tries to predict and handle the future.
If the signal is inverted on its way round the control loop, the system is said to have negative feedback; otherwise, the feedback is said to be positive. Negative feedback is often deliberately introduced to increase the stability and accuracy of a system, as in the feedback amplifier invented by Harold Stephen Black. This scheme can fail if the input changes faster than the system can respond to it. When this happens, the negative feedback signal begins to act as positive feedback, causing the output to oscillate or hunt. Positive feedback is usually an unwanted consequence of system behaviour.
With mechanical devices, hunting can be severe enough to destroy the device.
Harry Nyquist was an electrical engineer who contributed the Nyquist plot for determining the stability of feedback systems.