User perceptions of soft robot arms and fingers for healthcare

Safety and acceptability are critical issues when people are interacting with robots in healthcare. Traditional robot arms are hard and inflexible, and may cause harm to users on impact. Soft robotic arms may be safer and more acceptable in these situations. Similarly robot fingers made of soft materials may be more acceptable and safer than fingers made of hard materials. Robot designers need to know how best to design arms for healthcare scenarios. There is limited research on the acceptability of soft robotic arms and fingers to date. This study aimed to investigate people's reactions to the touch of soft robotic arms and fingers, compared to more traditional hard forms, and to human arms and fingers. A second aim was to investigate people's perceptions of the usefulness of the arms and fingers for healthcare tasks. Thirty five community participants were blindfolded and participated in touching tasks for: 3 arms (soft robot, hard robot, and human) and four fingers (soft robot, medium robot, hard robot, and human) in a randomised order. The soft arm was rated significantly more human-like but also more fragile and less reliable than the hard arm. Participants perceived the soft arm as good for intimate tasks like washing the body, but the hard arm was perceived as better for weight-bearing tasks. The soft finger was rated significantly more creepy, fragile and unreliable than the other fingers. The medium robot finger was rated the most human-like of the robot fingers and was the favourite robot finger. These findings suggest people perceive soft robots to be more fragile than hard robots and as more appropriate for personal tasks. Overly soft fingers may be too creepy to be acceptable.