Tan Lam Chung

Wall-Following Control of a Two-Wheeled Mobile Robot

Wall-following control problem for a mobile robot is to move it along a wall at a constant speed and keep a specified distance to the wall.This paper proposes wall-following controllers based on Lyapunov function candidate for a two-wheeled mobile robot (MR) to follow an unknown wall. The mobile robot is considered in terms of kinematic model in Cartesian coordinate system. Two wall-following feedback controllers are designed: full state feedback controller and observer-based controller. To design the former controller, the errors of distance and orientation of the mobile robot to the wall are defined, and the feedback controller based on Lyapunov function candidate is designed to guarantee that the errors converge to zero asymptotically. The latter controller is designed based on Busawon’s observer as only the distance error is measured. Additionally, the simulation and experimental results are included to illustrate the effectiveness of the proposed controllers.

Decentralized Control Design for Welding Mobile Manipulator

This paper presents a decentralized motion control method of welding mobile manipulators which use for welding in many industrial fields Major requirements of welding robots are accuracy, robust, and reliability so that they can substitute for the welders in hazardous and worse environment To do this, the manipulator has to take the torch tracking along a welding trajectory with a constant velocity and a constant heading angle, and the mobile-platform has to move to avoid the singularities of the manipulator In this paper, we develop a kinematic model of the mobile-platform and the manipulator as two separate subsystems With the idea that the manipulator can avoid the singularities by keeping its initial configuration in the welding process, the redundancy problem of system is solved by introducing the platform mobility to realize this idea Two controllers for the mobile-platform and the manipulator were designed, respectively, and the relationships between two controllers are the velocities of two subsystems Control laws are obtained based on the Lyapunov function to ensure the asymptotical stability of the system The simulation and experimental results show the effectiveness of the proposed controllers