Near minimum-time direct voltage control algorithms for wheeled mobile robots with current and voltage constraints

Abstract

Near minimum-time direct voltage control (DVC) algorithms synthesizing path-planning and path-following are proposed for wheeled mobile robots (WMRs) satisfying (i) initial and final postures and velocities as well as (ii) voltage and current constraints. To overcome nonholonomic and nonlinear properties of WMRs, we divide our control algorithm for cornering motion into three sections: TSD (Translational Section of Deceleration), RS (Rotational Section), and TSA (Translational Section of Acceleration). We developed off-line DVC algorithms using the quadratic problem with the object function minimizing the total time, where voltages to the motors are controlled directly without velocity/torque-servo modules. while satisfying the current constraints. Two methods of searching for the two control parameters (number of steps for RS M-R and velocity constraint in RS beta) were considered: The one is composed of one simple 1-dimensional search for beta, and the other is composed of two 1-dimensional searches for M-R and beta which has better performance. Performances of the proposed control algorithms are validated via various simulations.