Trust is important for collaboration.In hybrid teams of humans and robots, trust enables smooth collaboration and reduces risks.Just as collaboration between humans and robots differs from interpersonal collaboration, so does the nature of trust in human-robot interaction (HRI).Therefore, further investigations on trust formation and dissolution in HRI, factors affecting it, and means for keeping trust on an appropriate level are needed.However, our knowledge of interpersonal trust and trust in autonomous agents cannot be transferred directly to HRI.In this paper, we present a study with 32 participants on trust formation and dissolution as well as forecasting to influence trust in an industry robot.Results show differences in dynamics and factors of trust formation and dissolution.Additionally, we find that the effect of forecasting on trust depends on task success.These findings support the design of trustful human-robot interaction and corresponding robotic team members.

Robots are gradually being freed from their safety fences due to the advances in safety features integrated with most new robots. These robots enable a new form of human-robot interaction in which contact is possible. There are two robot-related factors that play a decisive role in the interaction dynamics and human perception in such a case – the motion speed and distance the robot keeps away from the human. Literature indicates that these factors influence whether humans perceive trust, safety, and comfort, which are essential components in the acceptance of robots by their end users. However, although speed and distance were intensively investigated in isolation, little is known about their combined effect. To this end, we conducted an experiment investigating the impact of the industrial robot arm’s approaching speed and stopping distance on the users’ trust, safety, and comfort while they were performing a collaborative task. Our results provide interesting insights into the implications of speed and trust. While we were able to replicate former studies in terms of implications of speed and distance, our data does not show any interaction effect between the two variables. However, our participants’ observations indicated that distance impacts the dependent variables more severely than speed.

In this work, we propose a computational robot trust model based on the predictability of the human partner as the main factor that impacts robot trust. Using this model and based on the robot’s knowledge about the task, the robot switches its behavior between conservative and normal, and adjusts the implemented safety mechanism as a function of the current robot trust level. We illustrate the proposed model impact on the outcome of the collaboration using a simple scenario. The results show a significant improvement in safety conditions of the human in collaboration with a robot at the cost of justifiable team performance reduction.