Quasi-Omnidirectional Fuzzy Control of a Climbing Robot for Inspection Tasks

Abstract

This work presents a novel method to quasi-omnidirectional control of an intelligent inspection robot designed to work inside and outside spherical storage tanks. The main objective is to promote a stable and smooth navigation during inspection tasks, ensuring the safety motion under adhesion and kinematic constraints. The robot is designed with four independent steerable magnetic wheels and a mechanical topology that allows the correct adjustment of adhesion system. A scheduled Fuzzy control is developed to achieve an optimal behavior and maximize the robot’s maneuverability, considering the magnetic restrictions of adhesion system and kinematic constraints of the inspection robot. The high adaptability of its mechanical topology (i.e., wheel misalignment, magnetic adhesion system, wheel camber and flexibilities in mechanical structure) and gravitational disturbance introduce many nonlinear characteristics in dynamic behavior that cannot be neglected, making the determination of its dynamic model a complex task. The Fuzzy approach allows to project a control system without a depth knowledge of its dynamic properties, to minimize the dynamic disturbances found in robot structure. Thus, the proposed motion control works according to the robot specific characteristics to ensure the quasi-omnidirectional motion over a reliable adhesion to tank surface and to minimize the effects of wheels kinematic constraints.