Path following control of mobile robots with model uncertaintybased on hierarchical fuzzy systems

Geometric path following control of mobile robots with nonholonomic constraints and model uncertainty is investigated.Based on hierarchical fuzzy systems,a robust indirect adaptive control scheme was developed to follow the desired geometric path,which removed the possible controller singularity and ensured the desired direction of the path.Having applied hierarchical fuzzy systems in the control architecture,the number of rules in a (standard) fuzzy controller was reduced greatly.A robust control term was used to compensate the approximation error of fuzzy systems,which could reduce the effect on tracking accuracy caused by the error.It was proved that the tracking error converged to the small neighbourhood of zero,and the tracking error could be decreased by enlarging properly design parameters in the robust control term.The test results verified the efficiency of the hierarchical adaptive fuzzy controller.