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A Model of Human Reaction Time to Dangerous Robot Arm Movements.

Helander MG; Karwan MH; Etherton J

Proceedings of the Human Factors Society 31st Annual Meeting, Rising to New Heights with Technology, October 19-23, 1987, New York City. Santa Monica, CA: Human Factors Society, 1987 Sep; 1:191-195

https://doi.org/10.1177/154193128703100212

00175988

A mathematical model was developed relating robot speed and human reaction time to risk of injury by the robot. The model was conceptually similar to a Model Human Processor developed by other investigators. The time for human information processing was divided into three components: perceptual time, decision making time, and motor response time. Perceptual time, estimated by a multiple regression technique, varied inversely with stimulus intensity and was typically in the range of 50 to 200 milliseconds. Decision making time was modeled, using the theory of signal detection, as a choice between the alternatives of hitting or not hitting the stop button. The probabilities of two correct and two incorrect outcomes were considered: hitting the stop button in response to a real threat, no response to a safe movement, failure to detect an unsafe movement, and incorrect perception that a movement is unsafe. Motor processor time was estimated using Fitts' law, as a logarithmic function of the distance to the stop button and the reciprocal of the stop button size. In a pilot experiment with nine male subjects, a linear relationship was found between robot arm speed and the distance the robot moved before it was stopped by an emergency button. The authors conclude that the safety interpretation of these results is difficult, and that more research is needed for a better understanding of the theoretical framework outlined.

Humans; Mathematical-models; Industrial-equipment; Safety-engineering; Machine-operation; Workplace-studies; Psychological-factors; Motion-perception; Industrial-safety