Early machines were simple machines that substituted one form of effort with a more humanly manageable effort, as lifting a large weight with a system of pulleys. Later machines were also able to substitute natural forms of energy, such as wind, tides, or flowing water, for human energy. Still later, early forms of automation were driven by clock type mechanisms or similar devices using some form of artificial power source - a wound-up spring, channelled flowing water, or steam - to produce some simple, repetitive action, such as moving figures, making music, or playing games. Such early moving devices, featuring human-like figures, were known as automatons and date from perhaps 300 BC. In 1801, the patent was issued for the automated loom using punched cards. This invention by Joseph Marie Jacquard revolutionized the textile industry.
The most visible part of modern automation can be said to be industrial robotics. Some advantages are repeatability, tighter quality control, higher efficiency, integration with business systems, increased productivity and reduction of labor. Some disadvantages are high capital requirements, severely decreased flexibility, and increased dependence on maintenance and repair. For example, Japan had to scrap many of its industrial robots when they were found to be incapable of adaptation to substantially changed production requirements and so not necessarily able to justify their high initial costs.
By the middle of the 20th century, automation had existed for many years on a small scale, using simple mechanical devices to automate simple manufacturing tasks. However the concept only became truly practical with the addition (and evolution) of the digital computer, whose flexibility allowed it to drive almost any sort of task. Digital computers with the required combination of speed, computing power, price, and size first started to appear in the 1960s. Before that time, industrial computers were almost exclusively analog computers and hybrid computers. Since then digital computers have taken over control of the vast majority of simple, repetitive tasks, and ever more semi-skilled and skilled tasks, with some food production and inspection being a notable exception. As anonymous so famously remarked, "for very many rapidly changing tasks, it is difficult to replace human beings, who are so easily retrainable within a wide range of tasks and, moreover, so inexpensively produced by unskilled labor."
There are still many jobs which are in no immediate danger of automation. No device has been invented which can match the human eye for accuracy and precision in many tasks; nor the human ear. Even the admittedly handicapped human is able to identify and distinguish among far more scents than any automated device. Human pattern recognition, language recognition, and language production ability is well beyond anything currently envisioned by automation engineers.
Specialised computers, referred to as programmable logic controllers (PLCs), are frequently used to synchronize the flow of inputs from (physical) sensors and events with the flow of outputs to actuators and events. This leads to precisely controlled actions that permit a tight control of almost any industrial process.
Human-machine interfaces (HMI) or computer human interfaces (CHI), formerly known as man-machine interfaces, are usually employed to communicate with PLCs and other computers, such as entering and monitoring temperatures or pressures for further automated control or emergency response. Service personnel who monitor and control these interfaces are often referred to as stationary engineers.
Another form of automation involving computers is test automation, where computer-controlled automated test equipment is programmed to simulate human testers in manually testing. This is often accomplished by using test automation tools to generate special scripts that direct the automated test equipment in exactly what to do in order to accomplish the tests..
Automation raises several important social issues. Among them is automation's impact on employment. Indeed, the Luddites were a social movement of English textile workers in the early 1800s who protested against Jacquard's automated weaving looms - often by destroying such textile machines - that they felt threatened their jobs. Since then, the term luddite has come to be applied freely to anyone who is against any advance of technology.
Some argue automation leads to higher employment. One author made the following case. When automation was first introduced, it caused widespread fear. It was thought that the displacement of human workers by computerized systems would lead to severe unemployment. In fact, the opposite has often been true, e.g., the freeing up of the labor force allowed more people to enter higher skilled jobs, which are typically higher paying. One odd side effect of this shift is that "unskilled labor" now benefits in many "First-world" nations, because fewer people are available to fill such jobs.
Some, such as technocrats, argue the reverse, at least in the long term. They argue that automation has only just begun and short-term conditions might partially obscure its long-term impact.
It appears that automation does devalue labor through its replacement with less-expensive machines; however, the overall effect of this on the workforce as a whole remains unclear. Today automation of the workforce is quite advanced, and continues to advance increasingly more rapidly throughout the world and is encroaching on ever more skilled jobs, yet during the same period the general well-being of most people in the world (where political factors have not muddied the picture) has increased dramatically. What role automation has played in these changes has not been well studied.
Millions of human telephone operators and answerers, throughout the world, have been replaced wholly (or almost wholly) by automated telephone switchboards and answering machines (not Indians or Chinese). Thousands of medical personnel have been replaced in many medical tasks from 'primary' screeners in electrocardiography or radiography, to laboratory analyses of human genes, sera, cells, and tissues by automated systems. Even physicians have been partly replaced by remote, automated robots and by highly sophisticated surgical robots that allow them to perform remotely and at levels of accuracy and precision otherwise not normally possible for the average physician.
Currently, for manufacturing companies, the purpose of automation has shifted from increasing productivity and reducing costs, to broader issues, such as increasing quality and flexibility in the manufacturing process.
The old focus on using automation simply to increase productivity and reduce costs was seen to be short-sighted, because it is also necessary to provide a skilled workforce who can make repairs and manage the machinery. Moreover, the initial costs of automation were high and often could not be recovered by the time entirely new manufacturing processes replaced the old.
Automation is now often applied primarily to increase quality in the manufacturing process, where automation can increase quality substantially. For example, automobile and truck pistons used to be installed into engines manually. This is rapidly being transitioned to automated machine installation, because the error rate for manual installment was around 1-1.5%, but has been reduced to 0.00001% with automation. Hazardous operations, such as oil refining, the manufacturing of industrial chemicals, and all forms of metal working, were always early contenders for automation.
Another major shift in automation is the increased emphasis on flexibility and convertibility in the manufacturing process. Manufacturers are increasingly demanding the ability to easily switch from manufacturing Product A to manufacturing Product B without having to completely rebuild the production lines.
One safety issue with automation is that while it is often viewed as a way to minimize human error in a system, increasing the degree and levels of automation also increases the consequences of error. For example, The Three Mile Island nuclear event was largely due to over-reliance on "automated safety" systems. Unfortunately, in the event, the designers had never anticipated the actual failure mode which occurred, so both the "automated safety" systems and their human overseers were innundated with vast amounts of largely irrelevant information. With automation we have machines designed by people with high levels of expertise, which operate at speeds well beyond human ability to react, being operated by people with relatively more limited education (as in the Bhopal disaster or Chernobyl disaster ). Ultimately, with increasing levels of automation over ever larger domains of activities, when something goes wrong the consequences rapidly approach.