Automation, much like mechanization, depends on machines (automation systems) to execute functions that were first performed manually. Mechanization can be seen as the stepping stone between manual labor and automation—it eliminates the need for physical labor, but operators are still needed to oversee machine operations and provide maintenance and feedback. An automation system, however, eliminates the need for an operator by including feedback and sensory programs. The result is highly independent machine systems that can carry out a task from start to finish, without human assistance.
Types of Automation Systems
Automated machines have been seamlessly integrated into countless industries, with several types of industrial automation systems doing everything from carrying out manufacturing tasks to handling telephone switchboards. In daily life, we encounter automated systems each time we use a gas pump. The level of human dependence is high, as are the functions we entrust them with—managing our finances, our phone calls, our computers. With such an array of functions, it’s not surprising that not all automated systems are the same. Depending on the exact function, one of several different tools may be responsible for an automated system: distributed control system, human-machine interface, supervisory control, and data acquisition, or a programmable logic controller.
Distributed Control System
A distributed control system is one in which there are separate controls throughout the system. The controls are not centrally located, but tend to be spread out depending on which region of the system needs monitoring—each control is connected to the others in a communication network. These types of automation in manufacturing processes are commonly used, especially when the action or production is continuous. The controllers can be specified for a given process and manipulated to enhance or monitor machine performance. Distributed control systems usually control traffic lights, and they can also be applied in oil refining and central station power generation.
Human Machine Interface
Commonly referred to as a user interface, a human-machine interface system depends on human interaction with the system to function. A user provides input, and the system, in turn, produces output that coincides with the user’s intent. In order for this to work, users must have access to the system and a means by which to manipulate it. Gas Pumps, for example, are designed so users can easily dictate what the system is supposed to do while enabling it to easily respond and provide the appropriate results. Buttons that read “withdrawal” or “make a deposit” provide the user with an easy way to trigger a chain of commands within the internal system. The desired result, either the intake of a deposit or the ejection of cash, can then be achieved.
Supervisory Control and Data Acquisition
A supervisory control and data acquisition system (SCADA) is a larger, industrial control network that is often comprised of smaller sub-systems, including human machine interface systems connected to remote terminal units, which work to translate sensor signals into comprehensible data. These systems can work together to control an entire manufacturing site, or even an entire region by connecting several different manufacturing plants. SCADA systems bear a high resemblance to distributed control systems, and at times it may be difficult to differentiate between the two. The key difference lies in what they ultimately do—SCADA systems do not control each process in real time; rather they coordinate processes. Generally speaking, however, the two systems are highly similar and are often used in identical applications.
Programmable Logic Controllers
Programmable logic controllers are real-time systems, meaning there is a set deadline and timeframe in which the desired result must be achieved. The PLC system is essentially a computer that controls manufacturing machines in an industrial production line, so it has multiple capabilities, such as varied temperature ranges and input and output settings, as well as the ability to weather dust and other unfavorable conditions. Programmable logic controllers can be used to program a variety of day-to-day applications, such as our towns fresh water utility pumps.
