Directly or on detours? How should industrial robots approximate humans?

Growing interest in industrial human-robot interaction (HRI) applications makes it necessary to look deeper into the design of systems, where humans collaborate, interact, or at least coexist with industrial robots. This study investigates the influence of the trajectory of an industrial robot´s Tool Center Point (TCP) on user well-being as well as human performance in the cooperative scenario HRI. Therefore, a study with a total of 19 participants was conducted. The subjects had to perform several tasks (visually interacting with the robot and performing an audio n-back task), while the robot made different motions in their vicinity. Results show that variable, i.e. non predictable, robot motions lead to reduced human well-being and performance. Consequently, non-predictable motions are not suited for use in HRI. Well-being and performance can be enhanced if the robot moves directly on a straight line from start to finish.