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The eyes are said to be the windows to the soul. If that’s true, then the human-machine interface (HMI) is the window into soul of the manufacturing process. While HMIs used to be mostly computer screens, keyboards and pushbuttons, recent technology advances are morphing that definition into new forms and functions—all in an ongoing effort to push engineers and operators’ vision ever further into their processes.
They used to be known as man-machine interfaces or MMIs, however, this definition was replaced by the more politically correct HMI in recent years, and that name has been overtaken by human-computer interface or HCI in Europe.
HMI expert Ian Nimmo reports that from the 1950s to the 1970s, operators viewed trends on HMIs mounted in steel panels in control rooms. However, with the advent of digital electronics in the 1980s, HMIs moved onto 12-inch and lately 17-inch computer screens that began to proliferate in industrial settings, and gave users a better keyhole view into applications.
In fact, Nimmo adds that users came to rely on these HMIs and associated alarms for what they couldn’t see, and sometimes became too dependent on them. Consequently, one of the main recent HMI trends is an effort by developers to get back to the big picture and help users to be more proactive, As a result, HMIs have expanded to include larger and larger overview screens and even huge video walls.
However, at the same time HMI graphics are being updated to bring back the look and feel of many of the old panel indicators and readouts they replaced. Basically, the old hardware-based constraints have gone away, and users can now interact with giant virtual panels that are more flexible and task-oriented for the simple reason that they are virtual.
Another HMI trend with roots in the past is data-sharing. In the past, there often were different consoles for different operator roles and responsibilities, so users had their own keyhole, but they didn’t share data with one another. Nimmo says this situation has just started to change in the past couple of years, and that some of the digital walls are adopting the capability of much older panels to show data from several process areas at the same time. This push to bring the big picture back to HMIs also is changing their subject awareness, so alarms, trends and graphics that used to be treated separately are now being treated together under one situation-awareness umbrella.
Similarly, developers are going beyond flat HMIs that basically copy P&ID drawings and are creating more hierarchical displays that go from overviews to unit views to detailed views and, finally, to detailed diagnostic views. They’re also seeking to make graphics more task-related by bringing together pieces that relate to one operator’s job, instead of having HMIs that just reflect the application’s or plant’s physical layout.
In the future, many HMIs also will add depth perception and perspective when they recognize predefined situations. For example, when a high-level or high-pressure event occurs, the on-screen representation of the equipment will be shown in perspective—perhaps moving from a square to a cube—which will allow it to show added depth, data and insight.
Because hardware is no longer a limiting factor, and because HMIs can be placed almost anywhere, users will likely move beyond simple message boards to the increased use of video conferencing, image capture and recognition, and field operators who can send back video-based data from the field.
It’s possible that process-control HMIs and handheld displays may one day show up on eyeglasses for field operators and maybe even neural interfaces. However, for the near future, operators will continue to need a standardized, better-prioritized, big-picture display of what’s actually happening in their applications, and HMI developers will remain focused on the best way to deliver it to them.
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