The hBracelet: a wearable haptic device for the distributed mechanotactile stimulation of the upper limb

Haptic interfaces are mechatronic devices designed to render tactile sensations; although they are typically based on robotic manipulators external to the human body, recently, interesting wearable solutions have been presented. Towards a more realistic feeling of virtual and remote environment interactions, we propose a novel wearable skin stretch device for the upper limb called "hBracelet." It consists of two main parts coupled with a linear actuator. Each part contains two servo actuators that move a belt. The device is capable of providing distributed mechanotactile stimulation on the arm by controlling the tension and the distance of the two belts in contact with the skin. When the motors spin in opposite directions, the belt presses into the user's arm, while when they spin in the same direction, the belt applies a shear force to the skin. Moreover, the linear actuator exerts longitudinal cues on the arm by moving the two parts of the device. In this work we illustrate the mechanical structure, working principle, and control strategies of the proposed wearable haptic display. We also present a qualitative experiment in a teleoperation scenario as a case study to demonstrate the effectiveness of the proposed haptic interface and to show how a human can take advantage of multiple haptic stimuli provided at the same time and on the same body area. The results show that the device is capable of successfully providing information about forces acting at the remote site, thus improving telepresence.