Development of a Variable-Softness Robot by Using Thermoresponsive Hydrogels for Haptic Interaction with Humans

摘要

It is important for social robots to be capable of changing its behavior or other capacity to sustain interaction with the user. In this paper, we discuss changing the softness of the body of a robot. The robot is supposed to be used in haptic interaction contexts such as therapy. To sustain the interest of the user, the robot changes the softness of its body elements and provide the user with variable tactile sensations depending on the haptic interaction history. In this paper, we report the design process of our creating robot prototypes by using a thermoresponsive gel that changes in viscoelasticity with temperature variations. The gel is soft in an inactive state, whereas it becomes hard when it is activated by heat. After identifying a chemical composition that was suitable for building the variable-softness robot, we created octopus-like prototypes having tentacles whose softness could be changed based on tactile sensing. User tests were conducted to check if participants could recognize such softness changes and to discuss the feasibility and prospects of this approach.