What are the 5 basic elements of a control system?

Control systems are necessary when operating automated machines in our technologically advancing world. Each control system has a design made for specific devices. However, when building one, an engineer must know what the basic elements of control systems are.

What Defines a Control System

A control system is a group of technological parts used to manipulate, manage, or control a machine or machine’s features. Control systems are in the vast majority of devices we use every day. Different items such as blenders, oscillating fans, or even a penlight use some form of a control system.

The parts that make a control system work can vary, but all of them do have essential elements that they share across the diverse array of devices.

General Defining Parts

While the science of creating and developing these core components has complicated structures that may only seem comprehensible to someone involved in control systems engineering services, their actual purpose is simple to understand. If you open up and dissect any piece of technology in your home, you will see that specific parts make that device work, from the wiring and plugs.

Controlled Process

With every action, there is a thought that puts the process into motion. All movement in a machine, whether the electric current or a gear moving, must have a plan of action and an intent. What a control system wishes to do will also determine what needs to be adjusted to fit this intent.

The control of a process monitors the state of production in the system to ensure that everything is consistent. Or, as stated above, if the production level needs to increase or decrease, the controlled process can adjust as needed.

Input

Every system involving the energy of flowing resources needs input to determine the output and allow entry into the system. The input is always the starting position for every system.

Every command, action, or adjustment goes into this point first. If you want a red light to blink in your system, it begins with the input; the request for the response.

Sensors

When a control system has a sudden shift in production due to physical parameters changing, a sensor is an object that detects the shift. A system can have multiple sensors to see slight changes in its mechanisms or have a variety of sensors to detect different possible changes. From this change observation, the sensor can send an alert to signal to other components or the person operating the control system that something has changed significantly.

Sensors are essential to understanding what is going on inside the system. For example, if water temperature is too high, we will need notification so it doesn’t become a problem down the line.

Output

The output of a control system is both different and connected to the input. As stated before, the input determines the output, and putting in particular values will create the same or different values from that input depending on the other variables that led up to that value. However, the input only allows for a request, whereas the output is the actual response and action.

An example of this would be turning a switch to the on position to power up a machine. The request to turn it on was input into the control system, and the output will turn it on. When you make a call to the machine to do something, the output meets with a response to the action it does.

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Controller of the System

Whether it be a switch, lever, or button, every technological device has a controller component to manipulate the system’s actions. The system controller can be as simple as an on/off switch or have multiple settings to change the machine’s output where it’s connected. Since handling control systems manually isn’t an option, you will need to use a controller to operate it and give it a directive.

Types

Control systems come in different forms with different purposes. The basic elements of control systems are still present, but their use is unique.

Open- and Closed-Loop

An open-loop system occurs in devices where the input doesn’t communicate with the output to create a result. The input makes a request that becomes active, and the output has no effect on the production.

A closed-loop system involves the input depending on the output. As explained in the “Output” section, the output can be different from the input, and in this system, the input is a dependent variable.

On-Off

This type of control system leans heavily o the use of sensors. When there is a change, the system activates and causes an opposite form.

An example would be a motion sensor connected to the lights in a room. The lights remain on as long as there is some activity within a set time. But after some time has passed and no movement is detected, the lights shut off to conserve energy.

The system remains on or inactive until a change is detected or has reached its threshold, which then causes a very sudden reaction to activate or deactivate a device.

Feedback Control

A feedback control system is also dependent on the sensors. By combining sensors and actuators, this system seeks to continuously remain at a specific variable by adjusting too low or high outputs.

The furnace in your home is a typical example, and it must constantly maintain the heat set on the meter. Natural elements such as the cold and heat in the air frequently change the temperature, which is why the furnace is on for long periods to regulate the house’s temperature.

Logic Control

A logic control system focuses on the varying parts of a system. By manipulating the different operations to cause specific reactions to occur, the processes of that system will change and create a new output. A mixture of sensors will utilize the reaction function of different parts of a machine to do this.

Control systems are essential for technology and will continue to advance until they become the primary form of every kind of machinery. But like anything in the world, the basic elements are just as crucial as any evolutionary traits. With the knowledge of the inner workings of the basic parts of control systems, using them will be easier as technology moves forward.

The controller section of the AC drive is the brain if the system. It typically consists of a microprocessor based CPU and memory that is used to process data once it is collected and stored. This controller section of the AC drive will process information received from the inputs of the drive and also from the feedback signals that will usually be a representation of the position or speed of the actuator. The controller will then issue commands to the amplifier section based on this information.

The amplifier section of the drive receives the commands from the control section. The amplifier then generates the power signal necessary for the actuator to drive the load with the correct speed and direction. The amplifier section of the AC drive is usually able to be further broken down into three sections of its own. The rectifier circuit, DC circuit, and inverter circuit. Most of the Allen Bradley AC drive repairs that we perform use a rectifier or SCR pre-charge circuit to reduce the instantaneous incoming current at power up, and supply continuous current while in operation. The DC circuit will contain both current and voltage filter components including a choke and parallel bus capacitors and may have some type of regenerative discharge circuitry. The inverter section of the AC drive will typically be comprised of insulated gate bipolar transistors or IGBTs. The switching control for the inverter circuit is provided by the control section of the AC drive. Using the switching control, the DC voltage supplied by the DC circuit, is changed in the inverter circuit to a pulse width modulated output that feeds the actuator of the motion control system.

The actuator portion of the system will most often be an induction AC motor or permanent magnet AC motor with windings and insulation that are specially designed to handle the heat and stress generated by a pulse width modulated output.

The feedback element of the motion control system may be handled by the system in a number of ways depending on the information needed. Encoders or resolvers can be used to provide feedback signals from the actuator in a closed loop control or hall effect sensors can provide feedback from the output of the AC drive in an open loop control. These feedback signals as previously mentioned will be a representation of the speed or position of the actuator and are used by the control section of the drive to determine what commands to provide to the other sections of the drive.

There are four basic elements of a typical motion control system. These are the controller, amplifier, actuator, and feedback. The complexity of each of these elements will vary depending on the types of applications for which they are designed and built. Rockwell Automation manufacturers a wide variety of these products under the Allen Bradley brand name.The controller section of the AC drive is the brain if the system. It typically consists of a microprocessor based CPU and memory that is used to process data once it is collected and stored. This controller section of the AC drive will process information received from the inputs of the drive and also from the feedback signals that will usually be a representation of the position or speed of the actuator. The controller will then issue commands to the amplifier section based on this information.The amplifier section of the drive receives the commands from the control section. The amplifier then generates the power signal necessary for the actuator to drive the load with the correct speed and direction. The amplifier section of the AC drive is usually able to be further broken down into three sections of its own. The rectifier circuit, DC circuit, and inverter circuit. Most of the Allen Bradley AC drive repairs that we perform use a rectifier or SCR pre-charge circuit to reduce the instantaneous incoming current at power up, and supply continuous current while in operation. The DC circuit will contain both current and voltage filter components including a choke and parallel bus capacitors and may have some type of regenerative discharge circuitry. The inverter section of the AC drive will typically be comprised of insulated gate bipolar transistors or IGBTs. The switching control for the inverter circuit is provided by the control section of the AC drive. Using the switching control, the DC voltage supplied by the DC circuit, is changed in the inverter circuit to a pulse width modulated output that feeds the actuator of the motion control system.The actuator portion of the system will most often be an induction AC motor or permanent magnet AC motor with windings and insulation that are specially designed to handle the heat and stress generated by a pulse width modulated output.The feedback element of the motion control system may be handled by the system in a number of ways depending on the information needed. Encoders or resolvers can be used to provide feedback signals from the actuator in a closed loop control or hall effect sensors can provide feedback from the output of the AC drive in an open loop control. These feedback signals as previously mentioned will be a representation of the speed or position of the actuator and are used by the control section of the drive to determine what commands to provide to the other sections of the drive.