Showing papers by "Hiroshi Ishida published in 2020"
TL;DR: The utilization of the downwashes of multicopters for gas-sensing applications is described, and two connected quadcopters hovering over an ethanol gas source was able to detect the gas even with a moderate cross-flow.
Abstract: This paper describes the utilization of the downwashes of multicopters for gas-sensing applications. Multirotor drones are an attractive platform for sensing applications. Their high maneuverability enables swift scanning of a target area with onboard sensors. When equipped with a gas sensor and used for gas-sensing applications, however, the strong downwash produced by the rotors poses a problem. When a multicopter is hovering at a low altitude, gas puffs leaked from a gas source on the ground are all blown away. Here, we propose to use two multicopters connected by a rod or a string and place a gas sensor at the midpoint of the rod/string. The downwash generated by each multicopter spreads radially after it impinges on the ground. When two multicopters are connected, the airflows spreading radially along the ground from the two multicopters impinge at the center and are deflected in the upward direction. Gas puffs wafting near the ground surface between the two multicopters are carried by this upward airflow to the gas sensor. Experimental results are presented to show the soundness of the proposed method. The connected quadcopters hovering over an ethanol gas source was able to detect the gas even with a moderate cross-flow.
7 citations
TL;DR: Simulation results are obtained in which the angular ranges of the chemical sample collection in real experiments is well reproduced, and although there are still some discrepancies between the simulation and experimental results, such simulations will facilitate the process of designing such devices.
Abstract: Here, we report on computational fluid dynamics (CFD) simulations conducted to develop a chemical sample collection device inspired by crayfish. The sensitivity of chemical sensors can be improved when used with a sniffing device. By collecting fluid samples from the surroundings, all solute species are also collected for the sensor. Crayfish generate jet-like water currents for this purpose. Compared to simply sucking water, food smells dissolved in the surrounding water can be more efficiently collected using the inflow induced by the jet discharge because of the smaller decay of the inflow velocity with the distance. Moreover, the angular range of water sample collection can be adjusted by changing the directions of the jet discharge. In our previous work, a chemical sample collection device that mimics the jet discharge of crayfish has been proposed. Here, we report CFD simulations of the flow fields generated by the device. By carefully configuring the simulation setups, we have obtained simulation results in which the angular ranges of the chemical sample collection in real experiments is well reproduced. Although there are still some discrepancies between the simulation and experimental results, such simulations will facilitate the process of designing such devices.
1 citations
25 Oct 2020
TL;DR: A mobile robot is reported that can effectively follow a chemical trail laid on the floor using three metal-oxide gas sensors, and four fans that serve as air curtains to prevent the gas sensors from responding to chemical vapor straying off to the side from the trail.
Abstract: We report a mobile robot that can effectively follow a chemical trail laid on the floor. Three metal-oxide gas sensors are mounted on the robot to detect its position with respect to the chemical trail, and four fans are aligned around each gas sensor. The effects of the airflows generated by the fans are two-fold. First, the airflows that impinge on the ground help bring the chemical vapor from a chemical trail to the gas sensors. Second, they serve as air curtains and prevent the gas sensors from responding to chemical vapor straying off to the side from the trail.
1 citations