Virtual Space with Scents Realized by Using Miniaturized OlfactoryDisplay and Computational Fluid Dynamics

我们开发了一种小型化的嗅觉显示器，实现了带有气味的虚拟空间。它由电渗透泵和表面声学装置组成。它比信用卡还小，可以在使用者的鼻子前混合多达8种气味成分。即使在低挥发性气味出现时，它也几乎没有气味持久性。然后，我们研究了一组气味成分，以涵盖广泛的气味。利用质谱数据和非负矩阵分解（NMF）方法提取基向量。我们用精油进行了气味近似实验。当我们使用30种气味成分时，近似识别出橙子、薄荷和黑胡椒的概率为90%。此外，我们还研究了NMF方法的距离度量。我们发现，当我们使用IS （Itakura-Saito）散度而不是欧氏距离和KL散度时，在大强度范围内获得了良好的近似能力。在此基础上，提出了基于CFD （Computational Fluid Dynamics）方法计算障碍物环境下任意位置气味强度的方法。用激光扫描仪测量室内几何形状，用热成像仪测量壁面温度分布，利用CFD方法得到了室内气味浓度的分布。此外，我们制作了同时呈现气味和气流的系统，从而增加了风的印象。用户感受到从液晶显示器传来的风和气味。可以控制虚拟气味源的位置。然后，在引入加热器后，我们在会议上展示了温暖的食物和饮料的气味。

We developed a miniaturized olfactory display and realize virtual space with scents. It consisted of electroosmotic pumps and a surface acoustic device. It is smaller than a credit card and can blend up to 8 odor components just in front of a user’s nose. It has little smell persistence even when a low-volatile scent is presented. Then, we studied a set of odor components to cover wide range of smells. The basis vectorswere extracted using mass-spectrum data and NMF (Nonnegative Matrix Factorization) method. We performed the experiment on odor approximation using essential oils. Approximated orange, mint and black pepper were identified with 90% probability when we used 30 odor components. Moreover, we studied the distance metric for NMF method. We found that good approximation capability over wide range of intensity was obtained when we used IS (Itakura-Saito)-divergence rather than the Euclidean distance and KL divergence.Then, we developed the method to calculate odor intensity at arbitrary position under the environment with obstacles using CFD (Computational Fluid Dynamics) method. The distribution of odor concentration was obtained using CFD method when the room geometry was measured by a laser scanner and wall-temperature distribution was measured by thermography. Furthermore, we fabricated the system to present odor and airflow simultaneously so that the impression of wind can be added. A user feels wind and odorcoming from the LCD monitor. The location of a virtual odor source can be controlled. Then, we presented odors from warm food and beverage at the conference after the introduction of a heater.