If you scan the Internet for the term Cyber-Physical Systems (or CPS) you will find many contributions discussing topics from mobile phones to time-aware software. CPS are objects that bring the physical (i.e., hardware) together with the computational world. In that sense, a modern car is an application of a CPS.
More and more, these systems not only use computational components but are an active participant of the cyber world. With this in mind, modern smart phones are actually excellent examples of a mobile CPS, since they have the ability to constantly receive updates from cyber space while at the same time provide data for the cyber world. Ever wondered how some Internet-based services are able to estimate traffic flow and project that information onto a map on your cell phone? In principle, the method is quite simple.
Ever since the invention of the mobile phone, telephone companies needed to know their customers' locations. This information was necessary to properly determine the cost of a phone call and allow incoming calls to be routed successfully. In 2011, the FCC required mobile phones to come with a GPS receiver.
Closing the loop between "knowing where a phone is" and the ability to transmit this data turned customers into human "flow meters." If traffic is moving along smoothly, customers are moving smoothly along the roads. There are, of course, a number of exceptions that must be filtered out by software analyzing the raw data. A delivery driver will stop frequently and someone commuting by bicycle or on foot generates the potential illusion of slowly moving traffic. While useful, this example has certainly nothing to do with automation, but the ability of an automation system to interact with its environment can have similarly useful side effects.
Today, most control systems are using a top-down approach. This means a PLC is responsible for anything and everything that happens along a production line. It reads sensors, makes decisions, and instructs other machine parts to perform machining or assembly operations. In well-designed automation systems, PLCs also monitor the health of all involved components. In most cases, through the implementation of RFID or 'direct part marking' solutions, the PLC knows which item is being processed where. With minor modifications, this has been the approach taken when designing automation systems— simple or complex—for the last 30 years. With the introduction of Ethernet-based automation systems, things finally started to change a bit, and engineers had the ability to reconsider this top-down approach.
In a sense, control engineers started implementing CPS before we even coined the term. For instance, with the introduction of Pepperl+Fuchs' IDENTControl RFID platform, engineers had the ability to design "self-aware" diagnostics methods. While the PLC still receives detailed status information concerning the operational status of the system, this information, for the first time, was also available via e-mail updates. In hindsight, this does not sound all that unusual. Today it is quite common to receive all sorts of e-mail indicating that some aspect of our digital existence has changed.
Modify your bank's online password, receive an e-mail. Pay a bill through PayPal, get another e-mail. Your next flight is delayed, yes, the airline will send you an e-mail. But when IDENTControl was released, applying this method to an automation device showed a lot of forward thinking. Granted, while it may not make a lot of sense to send an e-mail every time an RFID tag is read, sending such an e-mail when the read/write head gets disconnected or failed to communicate with the controller for any other reason is exceedingly useful.
Forget for a second the exact method by which IDENTControl was able to transmit such status information, but, rather, realize that relaying this data actually made IDENTControl a cyber-physical component capable of interacting with the environment—without the PLC having to get involved. While IDENTControl was well ahead of its time, we now know that using e-mails to accomplish this level of diagnostics is not the best method. And while very few users took advantage of letting the system send those e-mails, it should be clear that the concept is sound.
All we need is a better way of communicating status information and a better way for those people who need this information to receive that data. Once those topics have been addressed, CPS will allow automation systems to reduce the complexity (for the user) of automation, increase diagnostics and availability, and be part of a new industrial revolution.
Perhaps the PLC will remain indispensable for many years to come, perhaps not. But the proliferation of the smart phone and tablet has, at least for the time being, answered the question as to how people will get access to the information generated by automation hardware like the IDENTControl of the future.