Design and perception of wearable multi-contact haptic devices for social communication
Keywords: Bioengineering.

During social interactions, people use auditory, visual, and haptic (touch) cues to convey their thoughts, emotions, and intentions. Current technology allows humans to convey high-quality visual and auditory information but has limited ability to convey haptic expressions remotely. As people interact more through digital means rather than in person, it becomes important to have a way to be able to effectively communicate emotions remotely through touch as well. Systems that convey haptic signals could allow for improved distant socializing and empathetic remote human-human interaction. Due to hardware constraints and limitations in our knowledge regarding human haptic perception, it is difficult to create haptic devices that completely capture the complexity of human touch. This dissertation presents novel methods for the design and control of wearable multi-contact haptic devices, explores human haptic perception with these devices, and highlights how these devices can be used for various forms of social communication. First, we present the design, modeling, and control of two devices that use actuation of discrete contact points to create the illusion of a continuous and pleasant stroking sensation on the arm similar to what is felt during calming and comforting touch between humans. User studies validated that control parameters creating apparent motion with speeds that stimulate the specific touch receptors embedded in the skin which selectively respond to stroking create the most continuous and pleasant tactile stroking sensations. We also present two user studies: one which confirms the realism of the sensation applied and its similarity to human-human social touch and another that explores the effect of spacing between discrete contact points on the illusion of a continuous, pleasant stroking sensation. Second, we explore human haptic perception of touch cues on the forearm. We present a user study in which we directly compare the continuity and pleasantness of the stroking sensation generated via the devices described in the previous chapter and investigate how many contact points are necessary to create the illusion of tactile stroking. We find that you can create the illusion of a continuous and pleasant stroking sensation with as few as four discrete contact points. We also introduce a data-driven method for generating haptic signals that can communicate emotions. We present a user study in which we collected human-human touch data from couples and close friends communicating emotions through touch to the forearm in order to create a naturalistic social touch dataset. We use the touch data to produce haptic signals and validate that the signals can successfully communicate emotions with a multi-contact wearable haptic device. Last, we present the design and control of novel haptic devices that display normal skin deformation to the human back (dorsum) using arrays of soft pneumatic actuators. We targeted our haptic feedback to the back as it is a contact location during hugging interactions that is socially acceptable to test. We introduce the concept of macro-mini pneumatic actuation and how it can be used in wearable devices to help conform the device to the user's body and provide more salient haptic stimuli. A user study validated that participants have lower detection thresholds and can better localize the provided stimuli from macro-mini pouch actuators compared to a more traditional single pneumatic actuator. We discuss how the soft haptic vest containing the array of macro-mini actuators and the results from the user study can be used to replicate human-human hugging interactions. This dissertation presents new designs and control schemes for wearable multi-contact haptic devices for social communication and key insights regarding human haptic perception. The findings and technologies presented in this thesis could serve a variety of applications including social haptic devices for touch therapy, mediated social touch, and teleoperated social-physical human-robot interaction