A human factors study of population stereotypes concerning hand- held teach pendants

Abstract

This study was conducted to determined the population stereotypes of a group of novice robot users . The study focused on the stereotypes concerning the design of teach pendants for horizontally articulated robots. Expectancies from a written survey showed most of the naive users preferred to use human-like terms (e.g. elbow, wrist, arm) to identify the parts of a robot. Familiar motion terms (e.g. left, right, up, down) were preferred to describe the motions of the robot. The application of the names to a motion were dependent on the users orientation to the robot. While answering the survey, most users preferred to either be in front of or behind the robot model. Responses for control-motion expectancies in the horizontal plane were dependent on the users orientation to the robot. Controlmotion expectancies for vertical and rotational motions were independent of orientation. The study also compared the usability of pendant designs on two common industrial robots. One pendant (Pendant A) was designed with technical labeling (e.g. Y+/-, X+/-) and allowed for continuous control of the robot's speed. The other pendant (Pendant B) was designed with simple labeling (e.g. Left, Right, Forward, Back) and had three discrete speed settings. The required number of trials to reach an asymptote and the time to complete the last trial were not significantly different. When operating the robots, the users preferred to position themselves in front of the robot. Those who had positioned themselves behind the robot model while answering the survey shifted to the front of the real robot due to the robot obscuring their view. Users of Pendant A committed significantly fewer over control errors due to the continuous speed-control ability. Users of Pendant B tried to perform all the moves in the high-speed setting, rather than toggle to a slower speed. The users of Pendant B committed significantly more Left/Right (Y+/Y-) errors. Users commented that they were confused by whether the Left/Right control labels meant their left/right or the robot's left/right. The expectancies exhibited by the users were used to develop guidelines for the design of teach pendants. A four-button layout (top, bottom, left, right buttons causing forward, backward, left, right robot motion respectively), with a continuous speed control ability, was found to fit most users' control-movement expectancies.