Machine Design


To err is human. Anyone may be careless, inattentive, forgetful, reckless, or exhibit behavior beyond the limits of what is expected, desirable, or acceptable.

George A. Peters

Machine designers are painfully aware of the many ways users of their products can get into trouble, be it from abuse, misuse, improper care, miscommunication, or from a failure to read the operating instructions. People who use machines are often quickly blamed for accidents, malfunctions, and even poor equipment performance.

Unfortunately, merely identifying blameworthy people, punishable acts, or warning of the consequences of errors, usually does not prevent future mishaps. Quite often, mistakes are justified as part of the normal learning process, excused by the fact that people are not perfect, or tolerated because so little can be done to prevent human error. Such beliefs may promote the status quo, when the focus should be on realistic corrective and preventive actions.

Assurance of error minimization or elimination has taken on added urgency in the burgeoning global economy. Factors cited as responsible for the trend include increasingly widespread massproduced goods distributed to numerous cultures, worldwide competitive design and manufacture of components and products, the severe consequences of failures of certain high-tech equipment, litigation stemming from myriad new standards and government regulations, and sometimes unrealistic expectations regarding product performance.

Simple, common sense approaches may not help in identifying probable, predictable, or foreseeable human error. Many engineers simply do not have the training needed to ferret out the causes of errors, let alone come up with workable countermeasures or remedies. What analytic methods and test procedures should be used? What behavioral vectors are at play?

Fortunately, there are numerous books on the subject of human error, some entertaining, a few quite informative, and one that actually focuses on causes and correction (prevention). Goof proofing is a viable design goal. Properly implemented, the approach could help decide where to properly place blame; on a careless end user, or on the designer of a faulty product.

Dr. George A. Peters is a licensed professional engineer, attorney, and psychologist. He recently coauthored a book on human error that was published by CRC Press. Got a question about safety? You can reach Dr. Peters at [email protected]

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