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Automation in Manufacturing
Published in Edward Y. Uechi, Business Automation and Its Effect on the Labor Force, 2023
As early as the 1930s, industrial control systems were used to manage operations of power plants, oil refineries, chemical processing plants, and electricity transmission stations. Various names went by SCADA (Supervisory Control and Data Acquisition), DCS (Distributed Control System), and PCS (Process Control System). The industrial control system would have either a closed-loop feedback control or an open-loop feedback control. In an open-loop feedback control, the system would indicate a change in operation, and the human operator would react appropriately to the change as indicated. For example, a human operator would see an error light turn on and would then press a switch or turn a valve. In a closed-loop feedback control, a sensor detects a change and sends the change to a controller. The controller in turn makes an adjustment according to a computer software program written to handle the detected change. A human operator is not involved in the closed-loop feedback control. Earlier analog systems used relays, valves, and pneumatic gauges. Later digital systems used a computer and electronics.
Classical Vibration Control
Published in Chunling Du, Lihua Xie, Modeling and Control of Vibration in Mechanical Systems, 2018
When the system response is not acceptable, the value of the response is used to generate additional forces according to rules or laws such that the modified response behaves according to the design and within certain bounds. This results in a closed-loop system that incorporates feedback control, where the response is evaluated by a sensor and is fed back to an actuator that generates a force or motion. The purpose of designing a system with feedback force is to minimize unwanted behaviors and eliminate the effect of vibration on system performance in a desired manner. Feedback control provides a mechanism for tailoring system behavior to specific standards and needs. The block diagram depicting feedback control is in Figure 4.14. One can see that the signal from a block goes concurrently to other blocks or a summing point. The summing point indicates that the input and output signals are compared. The difference is an error that generates a control action. The disturbance or forcing is also shown being input directly to the plant or being injected to the output of the plant.
Energy Management Control Systems
Published in Moncef Krarti, Energy Audit of Building Systems, 2020
Generally, two categories of control systems can be distinguished: closed-loop systems and open-loop systems. In a closed-loop system (also known as a feedback control system), the sensors are directly affected by (and thus sense) the actions of the actuators. A typical control of a heating coil is an example of a closed-loop system. However, in an open-loop system (also called a feedforward control system), the sensors do not directly sense the actions of the controllers. The use of a timer to set the temperature of the heating coils would be an example of an open-loop system inasmuch as the time may not have a direct connection with the thermal load on the heating coils.
Stealth identification strategy for closed loop system structure
Published in International Journal of Systems Science, 2020
Hong Wang-jian, Ricardo A. Ramirez-Mendoza
Now many practical systems operate under feedback control situation due to the required safety of operation or to unstable behaviour of the plant, as occurs in many industrial processes, such as paper production, glass production, separation process like crystallization, etc. As there does not exist any feedback in open loop structure, so the output corresponding to the plant affects the input less. In closed loop system structure, a feedback controller is added to return the collected output back to the excited input. Then one error signal between the excited input and feedback output can be imposed on the plant to generate one correction action, which makes the output converge to its given value. The essences of closed loop system are to decrease the error by using the negative feedback controller, and to correct the deviation from the given value automatically. As the closed loop system can suppress the errors coming from the internal or external disturbances and achieve the specified control goal, so the closed loop system is most needed in all engineering fields.
Controller design for the closed loop system with non-interaction condition
Published in Systems Science & Control Engineering, 2020
Wang Jianhong, Ricardo A. Ramirez-Mendoza
Today many systems operate under feedback control situation, due to the required safety of operation or unstable behaviour of the plant, as occurs in many industrial processes, such as paper production, glass production, separation process like crystallization, etc. As there is any feedback effect in open loop structure, the plant output affects the input less. In the closed loop structure, a feedback controller is added to return the collected output back to the excited input. Then one error signal between the excited input and feedback output can be imposed on the plant to generate one correction action, which makes the plant output converge to a given value. The essences of closed loop system are to decrease the error using the negative feedback controller, and to correct the deviation from the given value automatically. As the closed loop system can suppress the errors coming from the internal or external disturbances and achieve the specified control goal, the closed loop system is most needed in all engineering fields.
Effect of movable insulation on performance of the Building integrated Semi-transparent Photovoltaic Thermal (BiSPVT) system for harsh cold climatic conditions: a case study
Published in International Journal of Ambient Energy, 2022
Neha Gupta, Pooja Rani, G. N. Tiwari
For automated blinds, a few of the algorithms used are time controlled for orientation and season or are based on a single solar radiation threshold value. This means such blinds are adjusted automatically depending on the amount of direct solar radiation that penetrates inside the room (Inoue and Itoh 1989; Leslie et al. 2005). Newsham (1994) suggested a blind control operation model based on the thermal comfort model assumption which means if the solar radiation with intensity greater than 233 fell on the occupants, the blinds will close. Similarly, Oscar Faber Associates (Foster and Oreszczyn 2001) chose the value of solar intensity to be 300 to represent threshold that occupants would start using the blinds. Recently automated systems may be used in buildings for energy savings and improving the thermal environment of the space. These systems facilitate effective utilisation of solar radiation and natural light. Control strategies for blinds and curtains are mainly divided into open loop and closed loop systems. Closed loop system receives the feedback, whereas open loop system does not. To explain this further, in an open loop system, the photo-sensor is placed only to detect the natural light and therefore is insensitive to the artificial light that it controls (no feedback). Today, there are automated window blinds available that are equipped with photometers either in an open loop or a closed loop control system. An example of a closed loop system can be explained as a series of indoor photosensors integrated with dimmers to maintain illuminance levels (Jain and Garg 2018).