But operator opinions are important. We obtain their feedback regularly on what is working or not working."
Strobhar adds, "The users themselves don't know what they need," offers Strobhar. "This is not unique to process plants. Asking someone what they want or need will not be UCD. You will end up with a wall of monitors with very colorful graphics. Operators want colorful displays because they're more aesthetically pleasing."
Often what operators say they want and what they use can be completely different. Sometimes they ignore the colorful graphics and 3D animation and bring up a plain old trend or faceplate display instead. But you'll never know unless you watch them.
The operator's console recorder (Figure 2) from Longwatch (www.longwatch.com) records everything the operator sees on the HMI. Automation system designers can use the recordings to see what operators do during an event, what displays they actually watch, and for training purposes.
PDA Does UCD in SCADA
Process and Data Automation (PDA, www.processanddata.com) revamped the control system for the Erie Wastewater Treatment plant in Erie, Penn. It was a typical upgrade project. That is, the plant had been updated in piecemeal fashion for the past 20 years; new equipment was not always compatible with the older hardware; and its SCADA system needed a complete upgrade. "This project required control, data collection and operator interface knowledge," says Tim Andrews, PDA's product manager.
"We identified the common problems with the system and where there needed to be improvements," added treatment plant operations supervisor Rob Munro. "Sometimes the equipment was so old that its screens showed applications we no longer used or identified equipment we no longer had."
"The operators and maintenance staff at the plant helped identify specific capabilities of equipment in the plant that weren't exploited in the old system," adds Joseph Snyder, PDA's president. "From this they had custom screens created that helped them drill into specific areas for details and troubleshooting purposes."
"The arrangement was ideal because it kept costs down and familiarized our electricians and maintenance staff with the new controls," Munro said. "Our employees worked by PDA's side and received critical on-the-job training, giving them a working knowledge of the system."
"We find many advantages to executing a project in this manner," Snyder explains. "The most glaring improvements, particularly in the short term, are ease of deployment and training, along with a much higher degree of ownership among the direct users. Users can better visualize the operation and correct irregular performance issues."
MGC Advanced Polymers (www.mapnylon.com) had similar problems when it updated the control system for its plant in Colonial Heights, Va. According to Andrew Digrys, project engineer at MGC, "The batch automation at the plant used custom code without any use of common or uniform control modules. The lack of a uniform approach resulted in custom and unnecessarily complex code that was poorly documented."
Once again, operators got involved. "Plant personnel participated in every phase of the design effort," reports Digrys. "They provided insight into the design deficiencies of the original codes, ensuring that processes and procedures were streamlined and simplified."
Performix (www.performixinc.com), a software vendor in Houston, Texas, also developed HMI screens with the help of operators. Fred Ungerer, COO at Performix, explains that his company was asked by a silicon products manufacturer to use UCD to improve batch recipe authoring. "A number of focus groups were held with operators between the ages of 18 to 65," explains Ungerer.
The result, depicted in Figure 3, ensured the operators would be one click away from the information or work that needed to be accomplished. "During subsequent testing and training sessions, the operators only required two or three practice orders to feel comfortable with the new solution," he says.
Blueprint for UCD
Concept Systems (www.conceptsystemsinc.com) a systems integrator in Albany, Ore., has a procedure for UCD-based projects. Michael Gurney, vice president, explains: "To achieve UCD, we work with a single point of contact at the company, where they are the conduit to involve all the other departments. Our job is to ask the right questions and draw out the information we need to design a quality system."
"At the early stages of the design, we produce a functional design document. Based on the customer's design needs, the document outlines what the entire project will entail, including an overview of the system's setup, operation and statistics, and how the new automated system will function with it."
The preliminary design stage is completed ahead of the actual programming. The customer must approve the preliminary HMIs before the design process goes forward.