Including olfactory cues in virtual reality (VR) would enhance user immersion in the virtual environment, and precise control of smell would facilitate a more realistic experience for users. In this paper, we present aBio, an active bi-olfactory display system that delivers scents precisely to specific locations rather than diffusing scented air into the atmosphere. aBio provides users with a natural olfactory experience in free air by colliding two vortex rings launched from dual speaker-based vortex generators, which also has the effect of cushioning the force of air impact. According to the various requests of different applications, the collision point of the vortex rings can be positioned anywhere in front of the user's nose. To verify the effectiveness of our device and understand user sensations when using different parameters in our system, we conduct a series of experiments and user studies. The results show that the proposed system is effective in the sense that users perceive smell without sensible haptic disturbance while the system consumes only a very small amount of fragrant essential oil. We believe that aBio has great potential for increasing the level of presence in VR by delivering smells with high efficiency.

Tai Chi Chuan (TCC) is a famous Chinese martial art. In addition to reading instruction books and watching demonstration videos, the traditional way of learning TCC for most people is to observe and mimic the movements of the coach. However, it is not easy for a novice to determine the weight distribution of the coach, and it is also difficult for a novice to strike a pose with the correct weight distribution. To help people to learn correct weight distribution when practicing TCC, we proposed a TCC augmented reality (AR)/mixed reality (MR) learning system that consists of a mixed reality head-mounted display (MR-HMD) and a pair of pressure sensing insoles. We have designed three kinds of visual hints to help people strike poses with correct weight distributions. Two user studies have shown that our TCC learning system is helpful for people to learn the weight distribution correctly and helpful for people to improve their proprioceptive sensitivity on weight distribution.