The effect of cognitive workload on decision authority assignment in human–robot collaboration

Abstract

Human–robot collaboration in dynamic industrial environments warrants robot flexibility and shifting between tasks. Adaptive robot behavior unavoidably carries decision-making needs regarding task allocation and scheduling. Such decisions can be made either by the human team members or autonomously, by the robot’s controlling algorithm. Human authority may help preserve situational awareness but increases mental demands due to increased responsibilities. Conversely, granting authority to the robot can offload the operator, at the cost of reduced intervention readiness. This paper aims to investigate the question of decision authority assignment in a human–robot team, in terms of performance, perceived workload and subjective preference. We hypothesized that the answer is influenced by the cognitive workload imposed on the human operator by the work process. An experiment with 21 participants was conducted, in which decision authority and induced workload through a secondary task were varied between trials. Results confirmed that operators can support the robot better when decision authority is allocated according to their workload. However, operator decision authority (a) may cause inferior performance at any secondary tasks performed in parallel with robot supervision and (b) increases perceived workload. Subjective preference was found to be evenly divided between the two levels of decision authority, and unaffected by task difficulty. In brief, if human–robot team performance is a priority, humans should be granted decision authority when their overall workload allows it. In high-workload conditions, system decision-making algorithms should be developed. Nonetheless, process designers should be mindful of the interpersonal differences between operators who are destined to collaborate with robots.