Control System Definition
Figure 1.1 Simplified description of a control system
Input and Output
A control system provides an output or response for a given input or stimulus. The input represents a desired response while the output is the actual response.
Two Control System configurations
1. Open-Loop Systems
2. Closed-Loop Systems
Open-Loop Systems
It Starts with a subsystem called an input transducer, which converts the form of the input to that used by the controller. The controller drives a process or a plant. The input is sometimes called the reference, while the output can be called the controlled variable. Other signals, such as disturbances are shown added to the controller and process outputs via summing junctions, which yield the algebraic sum of their input signals using associated signs.
The distinguishing characteristic of an open-loop system is that it cannot compensate for any disturbances that add to the controller's driving signal. The output of an open-loop system is corrupted not only by signals that add to the controller's commands but also by disturbances at the output (Disturbance 2 in Figure 1.2). The system cannot correct for these disturbances, either.
Examples of open-loop systems are:
1. Toaster
2. Mechanical systems consisting of mass, spring and damper with a constant force positioning the mass.
3. Operator Filling a tank with water
4. etc
Disadvantage of Open Loop System
The disadvantages of open-loop systems are sensitive to disturbances and inability to correct for these disturbances.
A control system consists of subsystems and processes (or plants) aassembled for the purpose of controlling the outputs of the processes. For example, a furnace produces heat as a result of the flow of fuel. In this process, subsystems called fuel valves and fuel-valve actuators are used to regulate the temperature of a room by controlling the heatoutput from the furnace. Other subsystems, such as thermostats, which act as sensors, measure the room temperature. In its simplest form, a control system provides an output or response for a given input or stimulus, as shown in Figure 1.1
Input and Output
A control system provides an output or response for a given input or stimulus. The input represents a desired response while the output is the actual response.
Two Control System configurations
1. Open-Loop Systems
2. Closed-Loop Systems
Open-Loop Systems
It Starts with a subsystem called an input transducer, which converts the form of the input to that used by the controller. The controller drives a process or a plant. The input is sometimes called the reference, while the output can be called the controlled variable. Other signals, such as disturbances are shown added to the controller and process outputs via summing junctions, which yield the algebraic sum of their input signals using associated signs.
The distinguishing characteristic of an open-loop system is that it cannot compensate for any disturbances that add to the controller's driving signal. The output of an open-loop system is corrupted not only by signals that add to the controller's commands but also by disturbances at the output (Disturbance 2 in Figure 1.2). The system cannot correct for these disturbances, either.
Figure 1.2: Open-loop system block diagram.
Examples of open-loop systems are:
1. Toaster
2. Mechanical systems consisting of mass, spring and damper with a constant force positioning the mass.
3. Operator Filling a tank with water
4. etc
Disadvantage of Open Loop System
The disadvantages of open-loop systems are sensitive to disturbances and inability to correct for these disturbances.
