Most human-robot handovers focus on how to approach human receivers and notify the readiness, few have investigated the effects of difference release behaviors of objects.
The whole handover process consists of three phases: the approach phase, the signal phase, and the transfer phase. Failures during the transfer phase have serious consequences:
- Early releases lead to dropped and broken objects,
- Not releasing while human receivers desired to takes the object breaks handover fluency and makes human receivers have bad handover experience.
To increase handover fluency and improve handover experience, we developed different manners for robots to release objects during a human-robot handover and plan to conduct a user study to investigate the effects of different types of release behaviors:
- Rigid release policy: The robot first fully extends its arm and, only when reached, detect pull and release the object in hand.
- Passive release policy: The robot attempts to extend its arm fully and detect pull along the way, and release the object accordingly. A pull is detected if the exerted force is over a pre-defined threshold during a certain time interval.
- Proactive release policy: The robot attempts to extend its arm fully and actively detect a force change pattern corresponding to human grasp effort along the way, and release the object early.