Open Loop Control Systems
In an open loop control system, the output can not be compared with the reference input. Thus, for each input reference relates to specific operating conditions, as a result, the provisions of the system depends on the calibration. With interference, the open loop control system can not perform the task as expected. Open-loop control system can be used, only if the relationship between inputs and outputs are known and there is no internal or external interference.
Comparison between closed loop control system and open-loop described below. An excess of a closed loop control system is the use of feedback makes the system response tarhadap relatively less sensitive to external interference and internal changes in the system parameters. Thus, it may be able to use components that are relatively less scrupulous and cheap to get control of the plant carefully, this may not be obtained on the open loop system.
And in terms of stability, open-loop control system is more easily made because stability is not a major issue.
Conversely, the stability can be an issue in a closed loop control system because of an error can occur due to excessive correction which may cause oscillation at a constant amplitude or changed. It should be emphasized that for the system with input that has been previously unknown and there is no interference, it is advisable to use the open-loop control.
Closed loop control system has advantages only if there is a disturbance that can not be predicted and / or changes can not be predicted on the system components. Note that limits the output power will determine the cost, weight and size of a control system. The number of components used in a closed loop control system will be more when compared to the open loop control system.
Closed loop control system definitely needs an instrument to measure some or all outputs. Therefore, the closed loop control system is generally larger and more costly. To minimize the power required by the system, if possible, can use open loop control. A suitable combination between open and closed loop control is usually less expensive and will give the desired overall system performance.
The term adaptive control system are described as follows. The dynamic characteristics of most of the control system is not constant due to several reasons, such as the deterioration of the performance of components with overtime or change parameters and round (for example, changes in mass and atmospheric conditions at the spacecraft control system). Although the influence of slight changes in the dynamic characteristics muted on the control system baited and forth, if the change of system and peripheral large enough, then a good system should have the ability to visualize themselves (adaptation).
Adaptation means the ability to self-regulate or modify themselves according to changes in the surrounding kondisii or structures that can not be predicted. Control systems which have an ability to adapt in a free state called adaptive control system. In the adaptive control system, the dynamic characteristics must be identified at any time so that the controller parameters can be set to maintain optimum performance.
This concept attracted much attention because the control system designers adaptive control system, in addition to following the change round, will also adjust the errors or uncertainty proper engineering design and will compensate for the damage fraction system components, thus increasing overall system reliability. The term control system with the reasoning described as follows below.
Some open-loop control systems that are often encountered can be converted into a closed loop control system, if the human operator is seen as controller, comparing the input-output and then perform corrective action based on the difference or error is obtained. If we are trying to analyze a closed loop control system involving a human operator such, we will encounter a difficult issue in writing the equations that describe the behavior of humans.
One of several complex factors in this case is the reasoning abilities of a human operator. If the operator has a lot of experience, he will become a better controller, and this should be taken into account in the analysis of such systems. The control system which has the ability to reason is called the control system with reasoning (learning control system). This concept is still fairly new and became interesting study.
