Abstract
Fore arm of articulated arm type haptic device is usually driven by a parallel link or a chain or a cogged belt. The parallel link is used most because of less play and simple structure. But there is a non-homogeneous stiffness characteristic. We adapt a duplicated parallel link mechanism for pseudo-mechanism haptic device in order to obtain the homogenized stiffness to explain a little nuance of reaction. The stiffness of parallel link mechanism changes according to the link angle. The link angle of a parallel link is 90 deg. advance to another one. Therefore, arm stiffness is homogeneous.
