A parallel elastic haptic thimble for wide bandwidth cutaneous feedback

Abstract

Design of wearable fingertip haptic devices is often a compromise between conflicting features: lightness and compactness, against rich and neat haptic feedback. On one side direct drive actuators (i.e. voice coils) provide a clean haptic feedback with high dynamics, with limited maximum output forces. On the other side mechanical transmissions with reduction can increase output force of micro sized motors, at the cost of slower and often noisy output signals. In this work we present a compact fingertip haptic device based on a parallel elastic mechanism: it merges the output of two differently designed actuators in a single, wide bandwidth haptic feedback. Each actuator is designed with a different role: one for rendering fast, high frequency force components, the other for rendering constant to low frequency components. In the work we present design and implementation of the device, followed by experimental characterization of its performance in terms of frequency response and rendering capabilities.