Mobile robot motion control in partially unknown environments using a sliding-mode fuzzy-logic controller

This paper studies the problem of motion and control law design for a mobile robot that moves inside a partially unknown environment with stationary obstacles and moving objects, under the assumption of parametric uncertainty in the model that describes the motion of the robot. A new variable structure system, that combines the basic principles of sliding-mode control with fuzzy logic, is presented which allows the robot to execute the desired motion. The proposed controller, named reduced complexity sliding-mode fuzzy-logic controller (RC-SMFLC), is characterised by its robustness and simplicity. The controller implements via fuzzy reasoning the following two rules: "IF sgn(e(t)(e) over dot(t)) < 0 THEN do not change the control action" and "IF sgn(e(t)(e) over dot(t)) > 0 THEN change the control action", where control action can be either an increase or a decrease of the control signal. The stability of the method is verified and illustrative numerical simulation examples are included. (C) 2000 Elsevier Science B.V. All rights reserved.