Author: John Mulindi
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The Goals of Robust Control Techniques
Robust control is normally used to handle systems with uncertainties & disturbances and with high performances. The objective of robust control is to be able to design controllers that achieve a desired level of performance and also, be able to handle a collection of uncertainty structures specified by the designer. A typical approach is to…
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Basic Elements of an Electronic Instrument
An electronic instrument is made up of the following key elements: Transducer This is the first sensing element and is needed only when measuring a non-electrical quantity such as pressure or temperature. Its task is to convert the non-electrical physical quantity into an electrical signal. An example of a transducer is a thermocouple for sensing…
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Key Causes of Uncertainty in Control Systems
One of the objectives of a control system is to achieve good plant performance in the face of uncertainty. The major sources of uncertainty in control are: Unmeasurable Perturbations Unmeasurable perturbations produce output deviations. With a controller in place, the achieved deviations must be below a user-defined bound. Modelling Errors Modelling errors can be classified…
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How Synchros are used as Position Transducers
Let’s consider the transformer in Figure 1.0 whose secondary winding can be rotated with the respect to the primary winding. At an angle ϴ, the output voltage will be given by: Vo = KVicosϴ where K is a constant The output amplitude is dependent on the angle, and the signal can be in phase or…
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Centralised vs. Decentralised Control Systems
Centralised control is usually carried out via computer software, having as inputs all the available sensors and producing signals for all the available actuators in the system. This control strategy is the most powerful, at least in theory, capable of extracting “optimal” performance. However, in practice, it requires non-standard apparatus (industrial computer data acquisition cards,…
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Actuators as Automation Components
An actuator is normally controlled by the controller. The actuator, in turn, changes the output of an automated process. The actuator in an automated process may in actual fact be several actuators, each of which provides an output that drives another in the series of actuators. Let’s consider the hydraulic actuator that controls the position…
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Open Systems Interconnection Communication (OSI) Model
Developed by the ISO (International Organization for Standards) in 1983, the Open Systems Interconnection (OSI) reference model divides communication functions into seven-layer standard protocol system. The OSI model is a framework for developing a coordinated system of standards. The seven layers are described as follows: 1 Physical Layer This layer describes the means for bit…
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Adaptive Control System
Adaptive control system adjusts to changes and modifies its parameters to fit the prevailing circumstances. The adaptive control system is based on the use of a microprocessor as the controller. Such a device enables the control mode and the control parameters employed to be adapted to fit the prevailing circumstances, modifying them as the circumstances…
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Control Modes in Automation Systems
The mode of control is the way in which a control system makes corrections relative to an error that exists between the setpoint of a controlled variable and its actual value. We have a number of ways (i.e. control modes) by which a control unit can react to an error signal and supply an output…
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The Importance of Power Line Communication in Smart Grid Operation
Power line communication (PLC) (i.e. the sending of data over the existing power cables) plays an important role in smart grid operation; Power line communication networks can access smart meters that are connected to feeders, the smart meter receives a signal coming from the transformer which is electrically connected to it. This helps to identify…