Showing papers by "Hiroshi Ishida published in 2009"

Design and implementation of spherical ultrasonic motor

Abstract: We present a mechanical design and implementation of spherical ultrasonic motor (SUSM) that is an actuator with multiple rotational degrees of freedom (multi-DOF). The motor is constructed of 3 annular stators and a spherical rotor and is much smaller and simpler than conventional multi-DOF mechanisms such as gimbals using servomotors. We designed a novel SUSM using experimental data from a single annular stator and a finite element method. The SUSM using a spherical rotor of diameter 20 mm without any reduction gear has demonstrated advantages of high responsiveness, good accuracy, and high torque at low speed. The dynamic implementation of SUSM was consistent with the driving model of SUSM based on a friction drive.

Blimp Robot for Three‐Dimensional Gas Distribution Mapping in Indoor Environment

Abstract: Mobile robots equipped with gas sensors can be used for automated measurement tasks including odor trail following, gas source localization, and gas distribution mapping. This article reports on the development of a blimp robot for mapping three‐dimensional gas distribution in indoor environments. The blimp robot is programmed to fly randomly so that its trajectory covers everywhere in the given indoor environment. The blimp is equipped with gas sensors to measure gas concentrations and an ultrasonic sonar to measure the height from the floor. The measured data are transmitted to an external PC via a wireless communication module. At the same time, a camera placed on the floor takes a picture of the blimp, and its location is recorded with the gas sensor responses. The experimental results indicate that the blimp robot is effective in mapping three‐dimensional gas concentration distribution in indoor environments.

Estimating gas-source location in outdoor environment using mobile robot equipped with gas sensors and anemometer

Abstract: This paper investigates the applicability of a gas-source localization method in outdoor environment. In the proposed method, a mobile robot is used to scan the area under consideration and to collect data on gas concentration and airflow velocity at various locations. The location of the gas source is estimated by applying a turbulent diffusion model of a gas plume to the data obtained by partial observation of the gas distribution in the given area. Discussion is made on the adjustment of the turbulent diffusion coefficient in the plume model to achieve successful estimation under various airflow conditions.

Odor Presentation with a Vivid Sense of Reality: Incorporating Fluid Dynamics Simulation into Olfactory Display

Abstract: The results of our current multidisciplinary research efforts on the development of an olfactory display system are demonstrated. To present odors with a vivid sense of reality, we propose to use computational fluid dynamics (CFD) simulation in conjunction with the olfactory display system. In this demonstration, an odor is released with a movie clip using the olfactory display. A CFD solver is employed to calculate the turbulent airflow field in the given environment and diffusion/advection of odor molecules from their source. The olfactory display system generates an odor with the concentration determined by the calculated odor distribution. The user is assumed to be a small animal slowly walking through a virtual room, and experiences the spread of the odor in the room.

Interactive Odor Playback Based on Fluid Dynamics Simulation

Abstract: This article describes the experiments on an interactive application of an olfactory display system into which computational fluid dynamics (CFD) simulation is incorporated. In the proposed system, the olfactory display is used to add special effects to movies and virtual reality systems by releasing odors relevant to the scenes shown on the computer screen. To provide high-presence olfactory stimuli to the users, a model of the environment shown in the scene is provided to a CFD solver. The airflow field in the environment and the dispersal of odor molecules from their source are then calculated. An odor blender is used to generate the odor with the concentration determined based on the calculated odor distribution. In the experiments, a virtual room was presented on a PC monitor, and the panel were asked to stroll in the room to find an odor source. The results showed the effectiveness of the CFD simulation in reproducing the spatial distribution of the odor in the virtual space.

Olfactory display: fluid dynamic considerations for realistic odor presentation

Abstract: This paper describes some fluid dynamic considerations for attaining realistic odor presentation using an olfactory display. Molecular diffusion is an extremely slow process and, therefore, odor molecules released from their source are spread by being carried off by airflow. Since the flow we encounter is almost always turbulent, the intensities of the odors delivered from their sources to our noses fluctuate randomly over time. Experimental results are presented to show the random fluctuations of odor intensity alleviate olfactory adaptation. When the odor vapor generation from an olfactory display device is randomly modulated, the odor is felt more persistently over time than in the case of the constant release of the odor vapor. The results of computational fluid dynamics simulations are also presented to show that our body temperature affects reception of odor vapors at our noses. Convective air currents in the upward direction are generated by our body temperature. They bring the odor vapor drifting along the floor up to our noses. Without the body temperature, such odor might not be detected. The detailed fluid dynamic considerations thus enable reproduction of realistic odor stimuli that we encounter in real-life scenarios.