Showing papers by "Hiroshi Ishida published in 2004"

Mobile robot navigation using vision and olfaction to search for a gas/odor source

Abstract: This paper presents a new approach to search for a gas/odor source using an autonomous mobile robot. The robot is equipped with a CMOS camera, gas sensors, and airflow sensors. When no gas is present, the robot looks for a salient object in the camera image. The robot approaches any object found in the field of view, and checks it with the gas sensors to see if the object is releasing gas. On the other hand, if the robot detects the presence of gas while wandering around the area, it turns toward the direction of the wind that carries the gas. The robot then looks for any visible object in that direction. These navigation strategies are implemented into the robot under the framework of the behavior-based subsumption architecture. Experimental results on the search for a leaking bottle in an indoor environment are presented to demonstrate the validity of the navigation strategies.

Dynamic gas sensor network for air pollution monitoring and its auto-calibration

Abstract: The use of a dynamic gas sensor network is proposed for air pollution monitoring, and its auto-calibration is discussed to achieve the maintenance-free operation. Although the gas sensor outputs generally show drift over time, frequent recalibration of a number of sensors in the network is a laborious task. To solve this problem, instead of the static network proposed in the related works, we propose to realize a dynamic gas sensor network by, e.g., placing sensors on vehicles running on the streets or placing some of them at fixed points and the others on vehicles. Since each sensor in the dynamic network often meets other sensors, calibration of that specific sensor can be performed by comparing the sensor outputs in such occasions. The sensors in the whole network can thus be calibrated eventually. The simulation results are presented to show that adjusting the sensor outputs to the average values of the sensors sharing the same site improves the measurement accuracy of the sensor network.

Liquid crystal display device having flexible substrates

Abstract: The LCD device includes a liquid crystal panel, a backlight unit, a circuit board disposed at rear side of the backlight unit, and a number of flexible substrates each mounting thereon a driver chip and connecting the terminals of the liquid crystal panel and the circuit board. The flexible substrate has a cut-out at each side edge thereof. A protrusion formed on the backlight unit or inner housing passes the cut-out to protrude toward the housing of the LCD device.

Three-dimensional gas-plume tracking using gas sensors and ultrasonic anemometer

Abstract: A new sensing system for gas-source localization is proposed. Gas molecules released from their source are carried by airflow and form an aerial trail called a plume. The authors' group has been developing smart sensing systems and robots that can track gas flows and find their sources for, e.g., fire alarming and detection of flammable or hazardous gas leakage. The present report demonstrates the first sensing system that has accomplished sensitive detection and reliable tracking of gas plumes in real-life indoor environments. An ultrasonic anemometer is used to accurately measure the 3D vector of the airflow direction. Six tin-oxide semiconductor gas sensors are placed around the anemometer to estimate the 3D direction of the gas concentration gradient. The direction to follow is obtained by combining those two vectors. The experimental results show that the proposed system can track a gas plume formed in a field of airflow as low as 3 cm/s.

Machine Olfaction for Mobile Robots

Abstract: Olfaction often plays an important role in orienting behaviors of animals. Famous examples are ants following pheromone trails marked on the ground and moths tracking aerial pheromone plumes. Inspired by these olfactory-guided behaviors, robotic systems that perform chemical trail following and plume tracking have been developed. In this chapter, the achievements so far are reviewed to demonstrate the current status of this new application of chemical sensor technologies.