TASTI Follows Chemical Trails with its Robot Tongue

This paper describes initial progress of a project to build a mobile robot that can detect and respond to non-volatile chemicals. Most people would be aware that sniffer dogs and insects such as ants are capable of following chemical trails that release volatile components into the air. However, chemicals with a molecular weight greater than 300 have very low volatility and do not produce a detectable concentration in air. A number of creatures sense deposits of low volatility chemicals by dissolving them before applying the solution to taste-sensory nerve endings. Snakes and many species of flies taste the ground when searching for food items. In this project a mobile robot called TASTI has been equipped with a robotic tongue that dissolves ionic compounds in distilled water and then measures the resulting ion concentration using a conductivity sensor. This paper describes the tongue sensor and a robot control algorithm that has been developed to use the tongue sensory data to follow trails of low-volatility chemicals deposited on the ground. Results of practical trail following experiments are also provided.