Active touch perception produced by airborne ultrasonic haptic hologram

A method to present volumetric haptic objects in the air using spatial modulation of ultrasound is proposed. Previous methods of airborne ultrasonic tactile display were based on vibrotactile radiation pressure and sensor feedback systems, which result in low spatial receptive resolution. The proposed approach produces a spatially standing haptic image using stationary ultrasonic waves that enable users to touch 3D images without depending on vibrotactile stimulation and sensor feedback. The omnidirectional spatial modulated haptic images are generated by a phased array surrounding a workspace, which enables enough power to feel shapes without vibrotactile technique. Compared with previous methods, the proposed method can create a completely silent image without temporal ultrasonic modulation noise that is free of the problems caused by feedback delay and errors. To investigate the active touch profiles of an ultrasonic image, this paper discusses a method to synthesize a haptic holographic image, the evaluation of our algorithm, and the results of pressure measurement and subjective experiments.