49 巻 (2011) 1 号 p. 54-61
As handheld tool navigation including surgical navigation, presenting tactile information is required in addition to the visual information. Especially, to present virtual tactile distribution at the holding parts of the fingers according to the contact condition between the tool and the important object such as organs enables users to minimize injuring them. However, spatially transparent stimulation which can superpose the tactile distribution at the holding parts without mediating the device has not been achieved. This study proposed a spatially transparent electrotactile display by using sensory shift which is caused by transcutaneous electrical nerve stimulus (TENS). We achieved tactile superposition by using the nerve anatomy and TENS. For developing the tactile Augmented Reality (AR) navigation system, tactile representation of the force vector which acts on the tool was proposed. The control of pulse rates at two electrodes enabled users to perceive the direction of the force vector. The subjective experiment letting a subject manipulate a tool without invading it into virtual obstacles was carried out. The result of the experiment showed that users could avoid invading virtual obstacles with less than 3mm depth.