FOUNDATIONS OF SWARM ROBOTIC CHEMICAL PLUME TRACING FROM A FLUID DYNAMICS PERSPECTIVE

Purpose - In light of the current international concerns with security and terrorism, interest is in- creasing on the topic of using robot swarms to locate the source of chemical hazards. This paper places this task, called chemical plume tracing (CPT), in the context of fluid dynamics. Design/Methodology/Approach - This paper provides a foundation for CPT based on the physics of fluid dynamics. The theoretical approach is founded upon source localization using the Divergence Theorem of vector calculus, and the fundamental underlying notion of the divergence of the chemical mass flux. A CPT algorithm called fluxotaxis is presented that follows the gradient of this mass flux to locate a chemical source emitter. Findings - Theoretical results are presented confirming that fluxotaxis will guide a robot swarm to- ward chemical sources, and away from misleading chemical sinks. Complementary empirical results demonstrate that in simulation a swarm of fluxotaxis-guided mobile robots rapidly converges on a source emitter despite obstacles, realistic vehicle constraints, and flow regimes ranging from lami- nar to turbulent. Fluxotaxis outperforms the two leading competitors, and the theoretical results are confirmed experimentally. Furthermore, initial experiments on real robots show promise for CPT in relatively uncontrolled indoor environments. Practical implications - A physics-based approach is shown to be a viable alternative to existing mainly biomimetic approaches to CPT. It has the advantage of being analyzable using standard physics analysis methods. Originality/value - The fluxotaxis algorithm for CPT is shown to be "correct" in the sense that it is