3D knit pneumatic actuators for wearable haptic displays

Abstract

Weft knit textiles are growing in popularity as materials for soft robotic applications due to their scalability and near infinite mechanical tunability. We leverage the benefits of 3D weft knitting to develop a novel method of manufacturing small scale (5-8 mm) pneumatic actuators that can be embedded across a distributed textile surface. Weft knitting (i.e., intarsia) enables seamless transitions between contrasting yarns and textile structures, which increases manufacturing resolution for small-scale actuators. Additionally, weft knitting enables mechanical property tunability beyond what is available off the shelf, enabling customizable actuation behavior. We demonstrate that 3D knit textile actuation properties, such as blocking force, free displacement, and bending stiffness, can be tuned by manipulating actuator design parameters, including (1) yarn tensile stiffness, (2) textile structural strain, (3) local textile geometry, and (4) input pressure. To demonstrate the manufacturability and scalability within a 3D wearable form factor, we build a haptic glove prototype with surface embedded actuation to mimic the sensation of touching and grasping virtual objects.