Nobuhiro Inuzuka

The Gathering Problem for Two Oblivious Robots with Unreliable Compasses

Anonymous mobile robots are often classified into synchronous, semi-synchronous, and asynchronous robots when discussing the pattern formation problem. For semi-synchronous robots, all patterns formable with memory are also formable without memory, with the single exception of forming a point (i.e., the gathering) by two robots. (All patterns formable with memory are formable without memory for synchronous robots, and little is known for asynchronous robots.) However, the gathering problem for two semi-synchronous robots without memory (called oblivious robots in this paper) is trivially solvable when their local coordinate systems are consistent, and the impossibility proof essentially uses the inconsistencies in their coordinate systems. Motivated by this, this paper investigates the magnitude of consistency between the local coordinate systems necessary and sufficient to solve the gathering problem for two oblivious robots under semi-synchronous and asynchronous models. To discuss the magnitude of consistency, we assume that each robot is equipped with an unreliable compass, the bearings of which may deviate from an absolute reference direction, and that the local coordinate system of each robot is determined by its compass. We consider two families of unreliable compasses, namely, static compasses with (possibly incorrect) constant bearings and dynamic compasses the bearings of which can change arbitrarily (immediately before a new look-compute-move cycle starts and after the last cycle ends). For each of the combinations of robot and compass models, we establish the condition on deviation

Gathering autonomous mobile robots with dynamic compasses: an optimal result

\phi

An Induction Algorithm Based on Fuzzy Logic Programming

that allows an algorithm to solve the gathering problem, where the deviation is measured by the largest angle formed between the

Tow-down Induction of Logic Programs from Incomplete Samples

x

A Mining Algorithm Using Property Items Extracted from Sampled Examples

-axis of a compass and the reference direction of the global coordinate system:

Convergence of mobile robots with uniformly-inaccurate sensors

\phi < \pi/2

Inducing Shogi Heuristics Using Inductive Logic Programming

for semi-synchronous and asynchronous robots with static compasses,

A Genetic Method for Evolutionary Agents in a Competitive Environment

\phi < \pi/4

Gathering Problem of Two Asynchronous Mobile Robots with Semi-dynamic Compasses

for semi-synchronous robots with dynamic compasses, and

Induction of Logic Programs with More Than One Recursive Clause by Analyzing Saturations

\phi < \pi/6