Introduction to Industrial Automation

Automation is a technique that can be used to reduce costs or improve the quality of products being manufactured. Automation can increase manufacturing speed while at the same time reduce the cost. Automation can also produce products with the same consistent good quality.

Note that Automation is not a straightforward solution to a financial problem however it is a valuable tool that can be used to improve product quality. With improved product quality, you will have lower costs. Producing inexpensive, high quality products is a good policy for any company.

Automation Control/Process Control

Automated processes can be controlled by humans operators, by computers or by a combination of the two. If a human operator is available to monitor and control a manufacturing process, then open loop control system may be acceptable. If a manufacturing process is automated, then it requires a closed loop control.

Fig 1

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Fig 1 and 2 above shows examples of open loop and closed loop control. One major difference is the presence of the sensor in the closed loop control system. The motor speed controller uses the feedback it receives from this sensor to verify that the speed is correct, and drives the actuator harder or softer until the correct speed is achieved. In the open loop control system, the operator uses his/her built-in sensors (eyes, ears etc.) and adjusts the actuator (via dials, switches etc.) until the output is correct. Since the operator provides the sensors and the intelligent control functions, these elements do not need to be built into an open loop manufacturing system.

Human operators are more inconsistent than properly programmed computers. Computerized controls, however can also make mistakes, when programmed to do so. Programming a computer to control a complex process is very difficulty. The recent development of affordable digital computers has made automation control possible.

Process control usually implies that the product is produced in a continuous stream. Automation control usually implies a sequence of mechanical steps. A camshaft is an automation controller because it mechanically sequences the steps in the operation of an internal combustion engine. Manufacturing processes are often sequenced by special digital computers known as programmable logic controllers (PLCs), which can detect and can switch electrical signals on and off. Digital computers are ideally suited for automation control type tasks because they consists of circuits each of which can only be either on or off.

Process control is now accomplished using digital computers. Digital controllers may be built into cases with dials and displays making them look like analogue ones. PLCs can also be programmed to operate as analog process controllers. They offer features which allow them to measure and change analog values. Robots and NC equipment use digital computers and a mixture of analog and digital circuit components to control “continuous” variables such as position and speed.
Digital computer control gives us soft automation meaning that they can be reprogrammed easily. Digital computers are also cheap, powerful, fast and compact. They offer many advantages to the automation user. A single digital controller can control several manufacturing processes. The designer only needs to ensure the computer can monitor and control all processes quickly enough and has some excess capacity for future changes.

You can also read: Introduction to Industrial Instrumentation

Soft automation systems can be programmed to detect and to adapt to changes in the work environment or to changes in demand. For example an NC lathe can modify its own speed if it detects a sudden change in the hardness of a raw material being cut. It may also change its own programming in response to a signal from another automated machine requesting a modification in a machined dimension.

Bottom line
Industrial automation is continuously improving, the developments in computers especially with regard to speed has led to more efficient automation systems. As we move into the future, we will see more and better automation systems that have greater performances than current ones.

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