Morphology for planar hexagonal modular self-reconfigurable robotic systems

This paper addresses the construction of a reconfiguration path planner for a planar hexagonal modular self-reconfigurable robotic system (MSRRS). A reconfiguration path planner is developed to determine the required sequence of individual module movements that transforms the shape of the system from an arbitrary initial configuration to a desired goal configuration in an optimal manner while enforcing several constraints and taking into account the kinematic model of the system. In this work, the path planner is designed to minimize the number of module movements during the reconfiguration while enforcing collision avoidance and connectivity constraints. The algorithmic design is based on a hierarchical multilayer approach, where upper layers decompose the problem into sub-problems solvable by lower layers. Each layer is dedicated to perform a specific task; therefore, the complete algorithm provides openness, flexibility and ease of modification or adaptation for other platforms. The core of the algorithm relies on a heuristic function and a Markov decision process (MDP) optimization to generate a near-optimal reconfiguration path planner and a control algorithm for HexBot shown in Figure 1, a lattice, homogenous, rigid, planar hexagonal MSRRS (Sadjadi et al., 2009).