| || || Mobile robots -- Automatic control|
| || || Path tracking and obstacle avoidance of a mobile robot using fuzzy logic based control |
Author: Vans, Edwin Raj
Institution: University of the South Pacific.
Award: M.Sc. Engineering
Subject: Mobile robots -- Automatic control, Fuzzy systems
Call No.: Pac TJ 211 .415 .V36 2015
Copyright:Over 80% of this thesis may be copied without the authors written permission
Abstract: In the area of mobile robot navigation, two common problems that exist are obstacle avoidance and path tracking. This thesis presents a proposed solution to these two problems by taking a fuzzy logic based approach. For the obstacle avoidance problem, a novel fuzzy controller structure is presented for the mobile robot with the application for exploration of a constrained environment with obstacles. The proposed fuzzy rule base contains redundancy in some of the fuzzy rules, that is several rule consequents could be used. At each discrete time step a random selection of one of these rule consequents is made. This is called Random Selection Fuzzy Rule Base (RS FRB). A modified version of the particle swarm optimization algorithm is used in order to tune the fuzzy controller parameters. A mobile robot simulator program was created to perform simulation experiments on different environments. Experiments were also performed on the hardware mobile robot platform. The results show the effectiveness of the proposed obstacle avoidance algorithm. For the path tracking problem, the proposed algorithm autonomously tracks straight and curved paths traced in the environment. In the proposed approach, a fuzzy steering controller, which controls the steering angle of the mobile robot for path tracking is combined with a fuzzy velocity controller, which controls the forward linear velocity of the mobile robot for safe path tracking. The fuzzy rule base is designed to emulate human driving behavior. The inputs to the fuzzy system are given by the vision system of the mobile robot. A camera is used to capture the images of the path ahead of the mobile robot and the vision system determines the lateral offset, the heading error and the curvature of the path. To experimentally test the path tracking algorithm, experiments were performed on straight and curved paths of different curvatures using the mobile robot hardware platform. The results obtained confirmed that the path tracking algorithm is effectual.