Explicit vs. Implicit - Communicating the Navigational Intent of Industrial Autonomous Mobile Robots

The coexistence of humans and Autonomous Mobile Robots (AMRs) in intralogistics is a growing reality. To enhance the usability of their interactions, AMRs can communicate their future trajectory to humans. This communication can be either implicit through their driving behavior, or explicit through additional signaling. We conducted a real-world participant study with 32 participants and a robot to compare two different communication tools: a floor projection as an explicit tool and a specific driving behavior as an implicit tool. We tested them in three scenarios: intersection, crossing, and bottleneck. We measured the interaction’s efficiency, legibility, and trust using quantitative data and questionnaires. We also asked participants to draw the expected trajectories of the AMR at the time of interaction. Our results showed no significant difference in the interaction time between the two communication tools. However, explicit communication increased the trust in the AMR and was perceived more easily by humans. On the other hand, explicit communication is more prone to misinterpretation by humans. Therefore, the design of explicit communication is crucial. The implemented implicit communication does not seem suitable for narrow corridor-like environments.