Development of a Wearable Four-Degrees-of-Freedom Force Feedback Device with a Clutch Mechanism Using Artificial Muscle Contraction

In a virtual reality (VR) space, wearing a headmounted display can help with the visualization of objects although users cannot experience realistic tactile sensations. Recently, several force feedback devices have been developed, including wearable devices that use straight-fiber-type pneumatic muscles and magnetorheological fluids. This allows the devices to render elastic, frictional, and viscous forces during spatially unrestricted movement. However, during friction and viscosity rendering, the elasticity of the artificial muscle is influenced by the elastic element of the muscle, preventing proper presentation of the force. Therefore, this study proposed a clutch mechanism to switch the force presentation of elastic elements by the contraction of artificial muscles. The mechanism was incorporated into a wearable four-degrees-of-freedom force feedback device, and its elastic, frictional, and viscous force feedback performances were quantitatively assessed via fundamental property experiments. Furthermore, a VR space was constructed to present the operator with force perceptions of virtual elastic, frictional, and viscous objects within that space, and the system's performance was qualitatively assessed. The results confirmed a reduction in the effect of elastic elements and an improvement in the presentation performance. Additionally, the use of this device in the VR space was confirmed to improve the realism of virtual objects in terms of friction and viscosity.