Designing the Operator Interface for Effective Alarm Management
Jamie Errington, Human Centered Solutions, LLP
Goal: enhance the effectiveness of people
Basic human capabilities are fixed
People rely on innate perceptual and cognitive capacities that evolved centuries ago
People read at the same speed today as 100 years ago
Many 1980s concepts are still applied today: user interfaces, control room design, roles and responsibilities
The paradox of automation: (not by technology alone"¦)
Better automation leads to more sophisticated processes
More sophisticated processes leads to more opportunities for error
We "fix" the increasing errors with still more automation
Consequently, when things go wrong, people lhave difficulty intervening to correct the problem.
When we look at an alarm management approach, there is an impact on operator effectiveness.
We need to tie whatever we do to improve it.
Alarm configuration rationalization
Alarm selection appropriate to unique operator actions
Alarm prioritization scheme (informative to focus attention
Alarm limits enable timely response
We need to address the operator interface because alarm configuration rationalization and alarm performance monitoring practices can improve operator effectiveness to a point; however these are necessary steps to improve alarm system impacts on operator performance. Best practices will not completely eliminate the occurrence of alarm floods
Operator interface design completes the loop.
Response Ã Activity Ã Interface challenges
OrientingÃ locating the problemÃ navigating to correct location while maintaining the "big picture" view
EvaluatingÃ Determining the problem Ã How do we get the right level of detail, accurate data, no distractions, easy access to information
ActingÃ Taking corrective actions Ã prevent inappropriate actions
AssessmentÃ Making sure we did the right things.
We need to design for perceptual processing. Operator interface design determines the extent that specific human information processing capabilities are used to perform work tasks. Designing for perceptual rather than cognitive processing imroves the efficiency and effectiveness of human performance.
Here's how sensing works: we have a sensory buffer (iconic memory) tha holds fixed detailed image of the world trhoughall the senses. It is extremely brief"”10 msec, but its capacity is unlimited.
Perception: images from sensor buffers recoded in perceptual centers of the brain. Selective attention can influence what we percieve out of the sensory buffer. Recoding is based on inate primitives and learned patterns"”actual patterns we respond to often unavailable to conscious awareness.
Preattentive vs. Selective Attention: a limited set of visual properties are detected very rapidly and accurately by the low level perceptual system and draw selective attention; these properties are called preattentive since their detection seems to precede selective attention. Typically, tasks that can be performed on large multi-element displays in less than 200 to 250 msec are considered preattentive. Preattentive properties include high intensity, movement, and emotive. Bright, loud, smelly, moving, emotional are examples.
Categories of visual coding that influence processing at the preattentive level are color position, form, and motion. Effective use of those attributes enables quick processing of some visual elements relative to others: salience.
Color, flicker, movement, flash, are all attributes of preattentive signals.
Key design techniques, then, include the use of distinctive exclusive color coding to draw attention to alarms and off normal conditions. Use a redundant visual codings cheme to address color perception deficiencies (10% of males are color blind and about 2% of females).
Use of motion to draw attention to unacknowledged alarms, not to be cool.
Provide on-screen navigation links associated with specific process equipment areas to focus constant attention on the alarm issues.
ASM and Novachem Operator Interface Case Study.
What's the difference between an ASM design and the traditional design. Hypothesis: the human-centerd style of operator interface improves operator performance for incident comparison.
Side by side comparison was made with single screen systems-- we didn't compare a dog with an elephant.
Case study involved a two part test for two groups of operators, with a pre-test and scenario testing to establish bias levels. 21 opeators participated, 10 with the traditional and 11 with the ASM design.
With the same number of years as a console operator, operator and operator at this plant and at this company, the ASM design showed about the same or a little better percentages of "panel rounds" correctly identified. However, in "time to solve" the problems the ASM design showed a 41% improvement.
On the average, opeators using the ASM version deteted an event before the alarm 48%
of the time"”
The longer it takes to solve an abnormal situation, the more the problem grows and propagates. Opeators using the tradtional interface could be distracted away by incoming alarms; once they left the region of the disturnbance to chase alarms, they did not solve the problem. They were never able to get back.
Need new alarm tone design: provide tones that localize the source. Provide tones that emphasize the urgency/nature of the alarm and reduce stress on the operator.
We need new alarm visualizations to address alarm flooding, with alternatives to imrpove use of alarm lists, and investigate alternatives to alarm lists.