Improvement of passive elements for wearable haptic displays

In this paper, three fundamental techniques to improve laminated passive elements are proposed for wearable haptic displays. First, a new shape of sheet surfaces in laminated passive elements is introduced. Sliding motion between laminated sheets causes unexpected bad effect to static stiffness. An effective triangle shape for sheet surfaces, which prevents from sliding, has been analyzed. This technique improves the stiffness of laminated elements. Next, a binary stiffness control method is proposed. It realizes arbitrary stiffness in a certain resolution only by on/off air valves. A parameter designing strategy for linear stiffness change is also described. Last, a technique to realize controllable multi-dof constraints is introduced. It realizes a multi-dof module of laminated elements, so it is an essential technique for multi-dof haptic devices. The validity of all the proposed techniques has been verified by some preliminary experiments.