Name:stu Date:2013-01-14 16:48:33 |
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Title: | some basic questions |
Content: | What is a digital control system? What are the characteristics of a digital control system? what are the differences between a digital control system and a normal control system? |
Reply: | In most modern engineering systems, there is a need to control the evolution with time of one or more of the system variables. Controllers are required to ensure satisfactory transient and steady-state behavior for these engineering systems. To guarantee satisfactory performance in the presence of disturbances and model uncertainty, most controllers in use today employ some form of negative feedback. A sensor is needed to measure the controlled variable and compare its behavior to a reference signal. Control action is based on an error signal defined as the difference between the reference and the actual values. The controller that manipulates the error signal to determine the desired control action has classically been an analog system, which includes electrical, fluid, pneu-matic, or mechanical components. These systems all have analog inputs and outputs (i.e., their input and output signals are defined over a continuous time interval and have values that are defined over a continuous range of amplitudes). In the past few decades, analog controllers have often been replaced by digital controllers whose inputs and outputs are defined at discrete time instances. The digital controllers are in the form of digital circuits, digital computers, or microprocessors. |
Date:2013-01-16 14:16:51 |
Name:stu Date:2013-01-14 16:45:11 |
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Title: |
A question in chapter 3 |
Content: |
How to model a digital control system? |
Reply: |
As in the case of analog control, mathematical models are needed for the analysis |
Date:2013-01-14 16:45:34 |