2D thermal wind sensor for mobile robot anemotaxis: Design and validation

Abstract

Locating odour sources with mobile robots is a difficult task with important applications. The most relevant environmental variables necessary to carry-out this task are the odour concentration and the wind velocity. This paper addresses the design and development of 2D thermal anemometers for very low wind speeds, such as the ones found indoors, and validate their performance with a mobile robot moving in a large wind tunnel. These anemometers use the wind disturbance around a prismatic shape to estimate the orientation of the airflow. Common shapes, such as cylinders and other regular prisms, were studied with a computational fluid dynamics (CFD) tool and with experimental prototypes. The prototypes were instrumented with a set of small self-heated thermistors, placed around the prism, in the measuring points of interest. This work employed Random Forests to process the output of the thermal elements and classify the airflow orientation in 36 intervals, producing anemometers with 10° resolution. Although all of the studied shapes could be employed to reconstruct the wind velocity vector, the one with best performance in terms of smoothness of response and robustness to turbulent data is a cylinder, which suggests that this method can be latter adapted to common cylindrical robots, exploiting their body as the structure of a similar anemometer.