Although electrical muscle stimulation (EMS) has been used in various haptic interfaces, haptic sense induced by EMS does not satisfactorily provide the full spectrum of haptic events. It is difficult to convey certain haptic sensations accurately through EMS. In this study, we aim to create the haptic sensation of the stiffness of an object by using muscle contraction induced by EMS. To simulate varying degrees of stiffness or elasticity of different objects, we must vary the displayed force depending on the displacement. To generate a haptic sensation corresponding to the force applied on the hand, we measure the generated force at the hand when electric stimulation is applied to a particular muscle. Once we have a model of the relationship between the applied electric stimulation and the generated force, we can determine the intensity of the electric stimulation required to simulate the target stiffness. In this study, we develop a haptic force display system that renders different levels of stiffness using EMS. We analyze the performance of our system by measuring the perceived stiffness in human experiments. The experimental results show a positive correlation between the target stiffness and perceived stiffness.
['Yuichi Kurita', 'Takaaki Ishikawa', 'Toshio Tsuji']
Stiffness Display by Muscle Contraction Via Electric Muscle Stimulation