Haptic displays implemented by controllable passive elements

Conventional robot systems consist of hard mechanical elements and actuators for exerting a force to objects efficiently. These systems are taking remarkable activities in industrial field but not in daily life of human. Main disadvantage of these robot systems is the fatal risk to human body when they lose control in the case of breakdown. On the contrary, we focus on flexible robot systems that work passively without actuators. These systems are intrinsically safe to human body since they never exert any excessive forces. In this paper, we present a novel passive element that varies its stiffness to internal vacuum pressure. This passive element is a soft vinyl tube embedded with Styrofoam beads, and is therefore soft and light contrary to conventional passive elements. Using the flexibility and the controllable stiffness, we developed a wearable haptic display that provides a sensation of elasticity and viscosity. The design of this new passive element and the applications to haptic displays are discussed.