Search

Two types of odor tracking systems that can be used for detecting the origin of fires, toxic chemical hazards, narcotics and pollutants are described. These equipment can also be used in locating people buried under a collapsed structure. The first system employs an autonomous robot that searches for an odor plume while the second uses a tool called an odor compass, in determining the source of the odor. The former has a distance resolution equal to the size of the robot but is more flexible and cheaper.

A three-dimensional (3-D) odor compass is proposed to develop a navigation tool used in searching for an odor source. The compass, which continuously points to the source, is equipped with four semiconductor gas sensors and a small fan to draw air to the sensors. The direction of the source is obtained by rotating the compass head to obtain the direction where the responses of the sensors along the horizontal and vertical directions are balanced. The following algorithmic improvements have been made to reduce the measurement time after the previous report on the two-dimensional (2-D) compass. First, the transient sensor response model is introduced to compensate the response delay of the gas sensors. Secondly, the head of the compass is made to rotate continuously and three-dimensionally during the directional estimation to gather plenty of data over a short time period. As a result, the measurement time at a practical level (20 s) has been achieved. The experimental results demonstrate the effectiveness of the compass in practical environments where the wind blows three-dimensionally and/or where the odor distribution is modified by an obstacle. Index Terms - Gas/odor source localization, semiconductor gas sensor, state equation.

A new circuit developed on the basis of a motional admittance method enables the correct measurement of the real resonant frequency shift and Q changes in a quartz crystal microbalance. The frequency values from the new circuit correspond to those from an impedance analyzer but not with those from Colpitt's oscillator at low Q variation values. Application of the new measurement circuit to a polyethylene glycol 2M-coated quartz resonator and quartz resonator gas sensor helps validate its efficiency.

The dynamic behavior of a chemical sensor both in spatial and temporal domains is examined. Frequency analysis is used for studying the sensor dynamics such as time constant and also for odor-source location.

HIROSHI ISHIDA [*,1] TAKAMICHI NAKAMOTO [2] TOYOSAKA MORIIZUMI [2] TIMO KIKAS [1] JIRI JANATA [1] Abstract. Many animals have the ability to search for odor sources by tracking their plumes. [...]