Robust and Efficient Covering of Unknown Continuous Domains with Simple, Ant-Like A(ge)nts

Abstract

Abstract-We propose a new "Mark-Ant-Walk" algorithm for robust and efficient covering of continuous domains by antlike robots with very limited capabilities. The robots can mark places visited with pheromone marks and sense the level of the pheromone in their local neighborhood. In case of multiple robots these pheromone marks can be sensed by all robots and provide the only way of (indirect) communication between the robots. The robots are assumed to be memoryless, and to have no information besides that mentioned above. Despite the robots' simplicity, we show that they are able, by running a very simple rule of behavior, to ensure efficient covering of arbitrary connected domains, including non-planar and multidimensional ones. The novelty of our algorithm lies in the fact that, unlike previously proposed methods, our algorithm works on continuous domains without relying on some "induced" underlying graph, that effectively reduces the problem to a discrete case of graph covering. In addition we demonstrate various benefits of our successive visits of the robot at the same location, that makes it suitable for patrolling.Finally we provide a new theoretical bound on covering time of a wide family of such mark and walk algorithms.

A review of swarm robotics tasks

“…Stigmergic communication has been implemented in past works using simulated pheromone traces [128,129,130,131,132]: the presence and intensity of pheromone at a given location is used as an indication that the location has been visited before. In some studies, pheromone is assumed to evaporate over time, analogously to what happens in nature with chemical traces, and this property is used to optimize repeated coverage of the same area [128], or to dynamically assign non-overlapping patrolling areas to different robots [132].…”

“…Wagner et al [128] devised some algorithms where robots drop evaporating pheromone along their path, and when choosing their walking path give precedence to areas with the lowest pheromone level. The techniques described in [128] rely on partitioning the environment in a discrete set of tiles, and modeling the partitioned arena as a graph where vertices represent the tiles; in [130], an analogous algorithm is proposed, which operates on continuous domains as opposed to graphs. In [129], experiments with real robots are reported, where the pheromone is represented by ink trails drawn by robots along their path with a pen.…”

On redundancy, efficiency, and robustness in coverage for multiple robots

“…A similar check is done for the opposite direction (lines 9-12). However, if the solution calls for moving bi-directionally, than the algorithm first checks which direction involves less movement, CCW (lines [13][14][15][16][17] or CW (18)(19)(20)(21)(22). In either case, the direction involving less movement is taken first, since it will be backtracked-over in the counter direction.…”

“…al. [16] propose a family of robust multi-robot ant-based algorithms which use approximate cellular decomposition. The algorithms involve little or no direct communications, and rely on no map memory, instead using simulated pheromones for communications.…”

The giving tree: constructing trees for efficient offline and online multi-robot coverage

“…al. [18] offer a robust coverage algorithm for ants in continuous domains. Sven-nebring and Koenig [22] offer a feasibility study for ant coverage.…”