Snake Effect: A Novel Haptic Illusion.

We present a novel, movement-based haptic illusion called the "snake effect." Unlike apparent motion or sensory saltation, the snake effect feels wavy and creepy as though the belly of a slithering snake is making and breaking contact with the skin. This illusion is achieved by modulating the amplitudes of vibrotactile pulses sent successively to an array of tactors. Pilot testing established the following signal parameters for creating the snake effect: a minimal pulse duration of 1.69 s, carrier frequency in the range of 200-300 Hz, amplitude modulation of the carrier with a sine, sine-squared or Gaussian waveform (shown to be more effective than a linear up-and-down ramp), and a peak amplitude of 30 dB above detection threshold. The main experiment examined the most effective signal onset asynchrony (SOA) ranges by estimating the upper and lower SOA thresholds using a one-up one-down adaptive procedure with interleaved ascending and descending series. The results indicate an optimal SOA range from 271.5 ms to 798 ms with a midpoint of 535 ms. The snake effect is a vivid illusion that can be used as a distinctive signal for encoding information and to enhance immersion and engagement in gaming and entertainment.

Preliminary study on force feedback of acupuncture in virtual reality based on the visible human / 中国医疗器械杂志

This paper discusses the application of virtual reality technology in the 3-D visible human body and acupuncture research. Based on the 3-D visible human fused with the localization information and hierarchy of acupoints, the paper analyzes the force against the needle and haptic rendering during the needle manipulation according to the physical properties of different tissues. A haptic model is constructed to demonstrate the force behaviors during acupuncture, and the force will be produced and passed to the manipulator by a force feedback device. It enriches the contents of 3-D visible human project, provides a dynamic simulation instrument for acupuncture teaching, and supplies a platform for acupuncture research.