Evolution of process control in manufacturing

STRANGE as it may seem, automation, as a concept, owes its origins to a 10th century Byzantine emperor whose throne was surrounded by artificial chirping birds and growling lions with wagging tails. The throne could move vertically at the emperor’s command, allowing him to gaze down upon his lowly subjects. Some believe the throne was powered by a primitive pressure control system. Perhaps.

From being used as a symbol of power and amusement in a bygone era, automation is today at the very core of modern manufacturing. The evolution of process control has been rapid and it is now the life-blood of any modern production facility.

Pneumatic systems developed in the early 1900s drove proportional control valves that allowed operators to modulate process valves remotely. This principle was used widely in automated bending, welding and injection welding machines that reduced manual intervention on the shop floor. But quality was still a major problem.

Many believe modern automated manufacturing really started in the early 1950s when the Massachusetts Institute of Technology produced the first numerical controlled (NC) machine. Punched cards or magnetic tapes controlled the work steps with shopfloor workers freed from routine measurement and control tasks.

In some ways, adding the ‘C’ or ‘computer’ to NC machines put the manufacturing process on steroids. CNC systems enabled highly-automated manufacturing and produced parts that closely matched the original CAD design with minimal human intervention.

In the early days, all control was done via pressure pipes that delivered a 3-15 psi signal. The rise of electronics pushed pressure pipes into oblivion, much to the joy of plant managers. Pipes gave way to 4-20 mA electrical signals and the industry was then ready to capitalise on the next big thing – the launch of microprocessors in the 1970s.

With process control instruments getting more intelligent, the next step was to allow them to communicate with each other. The plant manager in the 1990s was faced with a confusing number of communication network protocols, each one promising to make instruments on the shop floor communicate with others on that proprietary standard but not with others. 

Once manufacturers settled on one of the many fieldbus protocols and got their automation systems talking to each other, productivity, reporting and control rose significantly. 

A few years back, several makers banded together and offered a solution – go wireless. For a while, there was even one standard – WirelessHART which was approved in 2007. Manufacturers could pick from wireless versions of many instruments cutting down implementation costs and complexity for selected applications.

But the automation industry seeks devious ways to make the plant manager’s job as challenging as possible. Just when wireless seemed to be the panacea for kilometres of cables running through the plant, a couple of vendors came together to offer ISA100.11a to rival WirelessHART. 

From bobbing an emperor’s throne though to intelligent wireless sensors, the industry has come a long way. What’s on the horizon for the manufacturer who has to unscramble protocols, keep up to date with standards, boost productivity and untangle wires? In a throwback to a song that hit the airwaves in Australia a few years back, the cry is "What about me?"

And, manufacturers, the process control industry is listening.

The next big revolution is Human Centred Design where intelligent instruments won’t merely monitor processes and spit out reams of data but deliver information that is quickly useable. ABB, Invensys, Rockwell and Emerson are actively pursuing this course with the latter a very vocal proponent of this transformation. Instrument functionality will be developed with the user at its core as equipment vendors increasingly realise they’re serving the person not the machine or the process.

For automation, the best is yet to come.

So, was it some primitive, partly-automated pressure mechanism that gave our 10th century emperor his highs? Since the air pump was invented only in the 1600s and the hydraulic pump over a century later, it is likely a bunch of minions, hidden from sight, tugged furiously at a rope each time the emperor snapped his fingers.

Kevin Gomez is editor of Manufacturers’ Monthly sister publication, PACE.

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