Trajectory Tracking Control Of Nonholonomic Mobile Robot

Wheeled mobile robots belong to nonholonomic control systems, namely systems with nonintegrable constraints, while they are also typical strong nonlinear systems. Wheeled mobile robots have been an active area of research and development over the past ten years.The nonholonomic nature of wheeled mobile robots is associated with the assumption of the rolling without slipping of the wheels. This assumption means that there exits a set of unintegrable first-order differentiate constraints in the configuration variables. Although these nonholonomic constraints reduce the instantaneous movement that wheeled mobile robots can perform, wheeled mobile robots are still globally controlled. This feature makes design of feedback controller for wheeled mobile robots a challenging task. In practice, the development of wheeled mobile robots research field is promoted by the myriad of practical applications that can be addressed by mobile robots. Therefore the investigation of wheeled mobile robots with noholonomic constraints has a sigificant theoretical and practical meaning.Based on the reading and summarizing a lot of literatures references, this thesis studies the control problems focusing on trajectory tracking, constructing trajectory tracking controller.Firstly, based on a nonlinear state feedback control , as for trajectory tracking control,this thesis establishes posture error model denoted by Cartesian coordinates in local coordinates and proposes a nonlinear state feedback control law, which causes closed-loop system state space equation to have an isolated equilibrium state at origin. By Lyapunov candidate function method, this thesis concludes that the closed-loop system is globally uniformly asymptotically stable at origin. Through simulation of tracking a circular trajectory and analyse of control parameter, the results showed its effectiveness.Secondly, based on fuzzy control, this thesis studies trajectory tracking control of a nonholonomic mobile robot. Aimed at the large initial error, an error model is proposed. Two fuzzy controllers based on human driving behavior are designed. Angular velocity controller command is orientated by distance error and angle error. Acceleration controller command is orientated by distance error. Angular velocity and acceleration are simultaneously controlled to implement trajectory tracking of wheeled mobile...