Visual and Haptic Cues for Human-Robot Handover*

The adoption of robots outside their cages in conventional industrial scenarios requires not only safe human-robot interaction but also intuitive human-robot interactive communication. In human-robot collaborative tasks, the objective is to help humans in performing their job with less physical and cognitive effort. A collaborative task can involve the exchange of objects between the robot and the operator. However, the handover operation should be sufficiently intuitive, fluid, and natural for being accepted by the involved humans. Naturalness strongly depends on the speed of the object exchange and the way of communication. For the latter aspect, this paper proposes a multi-modal communication based on visual and haptic cues. Concerning the handover speed requirement, the paper proposes a high-performance visual servoing based on an Extended Kalman Filter (EKF) estimating object speed during the handover and a homography-based object tracking. The object safety is ensured by proper control of the robot grasp force based on a model-based approach exploiting tactile measurements. The same perception modality is also used as a source of haptic cues that make the handover intuitive and natural. Experiments of human-robot handovers through haptic and visual cues communication demonstrate the effectiveness of the proposed approach.