Biomimetic design of an ultra-compact and light-weight soft muscle glove

Wearable robotic hand devices can support people doing hand-intensive tasks by reducing the physical stress and strain on the human hand. For the safety and comfort of the user, such a device should be compatible and inconspicuous. Based on these two requirements, this paper presents a biomimetic design of a wearable robotic hand device called soft muscle glove, aiming to restore the salient features and functionalities of the human hand. Inspired by the hand musculature, the soft structure of the glove contains strings, bands and shape memory alloy (SMA) spring actuators to replicate the functionalities of tendons, pulleys and muscles in the human hand. The low-mass and small-size SMA spring actuator allows an ultra-compact and light-weight design of the glove with high dexterity. The glove weighs in total 85.03 g inclusive of the actuators and microcontroller. The performance of the muscle glove was experimentally investigated through hand function tests. The experimental results suggest that the glove can achieve functional range of motion of the human hand and can perform a wide range of grasp types defined in grasp taxonomy. Moreover, the grasping performance of the muscle glove with coupled and uncoupled flexion of the finger joints was compared. The uncoupled control shows a better matching between the grasp posture and the objects form, contributing to more efficient force transmission. This confirms the benefits of the proposed highly biomimetic design.