Effective physical human-robot interaction
(pHRI) depends on how humans can communicate their
intentions for movement with others. While it is speculated that
small interaction forces contain significant information to
convey the specific movement intention of physical humanhuman
interaction (pHHI), the underlying mechanism for
humans to infer intention from such small forces is largely
unknown. The hypothesis in this work is that the sensitivity to a
small interaction force applied at the hand is affected by the
movement of the arm that is affected by the arm stiffness. For
this, a haptic robot was used to provide the endpoint interaction
forces to the arm of seated human participants. They were asked
to determine one of the four directions of the applied robot
interaction force without visual feedback. Variations of levels of
interaction force as well as arm muscle contraction were applied.
The results imply that human’s ability to identify and respond
to the correct direction of small interaction forces was lower
when the alignment of human arm movement with respect to the
force direction was higher. In addition, the sensitivity to the
direction of the small interaction force was high when the arm
stiffness was low. It is also speculated that humans lower their
arm stiffness to be more sensitive to smaller interaction forces.
These results will help develop human-like pHRI systems for
various applications.
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Wrapped Haptic Display for Communicating Physical Robot Learning
Physical interaction between humans and robots can help robots learn to perform complex tasks. The robot arm gains information by observing how the human kinesthetically guides it throughout the task. While prior works focus on how the robot learns, it is equally important that this learning is transparent to the human teacher. Visual displays that show the robot’s uncertainty can potentially communicate this information; however, we hypothesize that visual feedback mechanisms miss out on the physical connection between the human and robot. In this work we present a soft haptic display that wraps around and conforms to the surface of a robot arm, adding a haptic signal at an existing point of contact without significantly affecting the interaction. We demonstrate how soft actuation creates a salient haptic signal while still allowing flexibility in device mounting. Using a psychophysics experiment, we show that users can accurately distinguish inflation levels of the wrapped display with an average Weber fraction of 11.4%. When we place the wrapped display around the arm of a robotic manipulator, users are able to interpret and leverage the haptic
signal in sample robot learning tasks, improving identification of areas where the robot needs more training and enabling the user to provide better demonstrations. See videos of our device and user studies here: https://youtu.be/tX-2Tqeb9Nw
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- NSF-PAR ID:
- 10340739
- Date Published:
- Journal Name:
- 2022 IEEE 5th International Conference on Soft Robotics (RoboSoft)
- Page Range / eLocation ID:
- 823 to 830
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/ROBOSOFT54090.2022.9762210
