Pneumatic tubular body fixture for wearable assistive device — Analysis and design of active cuff to hold upper limb —

This paper proposes a pneumatic tubular body fixture for a wearable assistive device in order to hold a user body in simple wearing actions and with comfort. The pneumatic body fixture, called active cuff, is composed of multiple sets of a pneumatic actuator module which are actively transformed by compressed air. This transformed module wraps and holds a part of a user´s body so that a wearable assistive device can be mounted on the user´s body with less effort in a short time. The elastic material of the pneumatic actuator module also contributes a tactile and pressure sensation of a contact with the environment as if we could feel those sensations through our clothes. The pneumatic actuator is modeled by a beam structure and then deformation of the pneumatic actuator is simulated by finite element method for an active cuff design. The maximum holding force of the developed active cuff is about 6 kilograms, which is enough to hold an upper limb. The active cuff changes the holding points to keep blood flow of the holding area iteratively and alternatively using three couples of pneumatic actuator modules of the active cuff. Through some experiments, we confirmed that the active cuff enhanced the convenience and comfort of the wearable robot from the viewpoints of easiness to wear and the contact pressure distribution.