Minimum-time grid coverage trajectory planning algorithm for mobile robots with battery voltage constraints

Grid coverage trajectory planning is the trajectory determination that a robot must follow in order to pass over all the grid points in a given environment. Applications include de-mining, inspection, exploration, reconnaissance, etc. In this paper, a minimum-time grid coverage trajectory planning (GCTP) algorithm is proposed for two-wheeled mobile robots (TMRs) satisfying (i) initial and final postures and velocities as well as (ii) battery voltage constraints. First, we list various candidates of turning path and performed an analysis on the time consumption of candidates, which are generated by combinations of standard paths such as translational path (T), rotational path (composed of arcs and clothoids). We considered five turning path candidates: T, R, C-R-C, R-T-R, and C-R-T-R-C (R means rotational curve path to rotate clockwise, C means rotational curve path to rotate counter-clockwise), and suggested a minimum time turning trajectory planning algorithm with efficient iterative binary search algorithm. We performed various computer simulations to find the minimum-time grid coverage trajectory. Simulation results show that the C-R-T-R-C path is the most efficient planning algorithm, which enables wheeled mobile robot to reduce the grid coverage time up to 16%.