Search Beville.com

This website does not use cookies. Read Privacy Policy here.
.
Beville Logo - human factors engineering consultants

CAN A CONTROL SYSTEM BE OPERATED CORRECTLY IF THE USER HAS AN INCORRECT CONCEPTUAL MODEL?

NEWSLETTER ARTICLE

Good conceptual models are what allow us to predict the effects of our actions. Conceptual models allow the user to predict the machine's output in response to controller inputs (for all of you control systems people out there, this could also be called a transfer function). There is no need to completely understand the physics or chemistry of how a machine works in order to properly use it. All we need to understand is the relationship between our controller inputs and the outputs of the machine. Conceptual models are what allow a person to visualize and mentally simulate the machine's operation. The goal of every control system designer is to develop a controller display which conveys precise information that allows the user to develop a good conceptual model.

Conversely, incorrect or incomplete conceptual models are often what cause us to operate machines incorrectly. A poorly or incorrectly designed controller display will cause the user to develop an incorrect conceptual model and cause that person to incorrectly visualize and mentally simulate the machine's operation. Unfortunately, examples of poor controller display design are all too common in every day life, and the user often blames himself as in, "Geez, I must be stupid." Poorly designed control displays account for a large number of the infamous "operator error" accidents.

A good example of poor display design which led to a poor conceptual model can be found in Donald Norman's, The Design of Everyday Things, (Doubleday Publishing Group Inc., New York, New York, 1990, page 14). Norman uses the example of the temperature controls of a refrigerator. The author wanted to make the freezer warmer and keep the fresh food compartment a constant temperature.

The poor design of the controls led the author to construct an incorrect conceptual model of the refrigerator's inner workings and system setup. This, in turn, made it difficult for him to correctly increase the temperature in the freezer compartment while maintaining constant temperature in the fresh food compartment.

It is interesting to note that the refrigerator designer used a good deal of labeling on their controller display. Unfortunately though, the labeling made operation of the refrigerator incomprehensible for situations which were not defined by the labeling. No amount of labeling will fully compensate for a poorly designed display.

Violation of information processing principles and display design principles while designing displays will lead to poor conceptual model development, and result in design-induced error. Humans are exceedingly flexible and can adapt and learn to use poorly designed control display systems. However, the poor designs increase the likelihood that the operator will make errors when operating the controls. If the operation of a controller is not intuitively obvious, the display is probably poorly designed.

Copyright 1993 Beville Operator Performance Specialists, Inc., All Rights Reserved

For further information, visit the links below.

| Alarm & Display System Analysis Overview | Alarm Management | Display Design | Alarm & Display Design Seminar | Beville Shape Calculator -Excel download | Alarm Distribution Estimator - Excel download |


RELATED EXTERNAL MEDIA

Link Published By
Operator Interfaces Expand Human Factors Automation World
How to Build a Better Operator - ABB Automation & Power World Control Design
Operators Get More Help Chemical Processing
Simple, Strong and Easy-to-Use Control Global
DCS Console Operator Issues in Related Industries TAPPI
Operator Interfaces: Moving from Comfortable to Most Effective Automation World
BEVILLE NEWS

The 2024 Spring Meeting of the Center for Operator Performance will take place on April 16-18, 2024, in Pine Bend, MN/Hybrid. For more information on this and future meetings, please contact Lisa Via. Guests are always welcome!

Our most recent newsletter is now available. Click here!


David Strobhar's book, "Human Factors in Process Plant Operation," is now available in both hardcover and Kindle e-book.

Copyright 1996-2024 Beville Operator Performance Specialists, Inc. All rights reserved. (937)434-1093. Beville@Beville.com