Mobile Robot is one of the most important parts of Robotics. It is very significant to do the research on mobile robots’ environment modeling, motion control, obstacle avoiding, and robot navigation. Focusing on the sensing system and control system for wheeled mobile robot working in an unknown environment, the research of environment modeling, motion control, obstacle avoidance and robot navigation are presented in this thesis. Firstly, the research on the history, trend, navigation and motion control for mobile robots are reviewed, and the background, main research contents, and the research significance of this thesis are introduced in this part. Secondly, focuses on the trajectory tracking control problem for wheeled mobile robots, a discrete sliding mode control laws based on the dynamical model have been addressed. The experimental results show that the proposed approach can be used to realize trajectory tracking with a well precision despite dynamical disturbances and it has robust property compared with a classical inverse kinematic controller. Thirdly, the characteristic, property and limitation of ultrasonic sensors are analyzed, and a DSP based information acquisition and processing system of ultrasonic sensors array is presented. The experimental results show that the proposed system is satisfactory for mobile robot environment sensing and obstacle avoiding applications. Fourthly, a novel approach to mobile robot environment modeling based on principal component analysis of ultrasonic sensors array data is presented. A principal components space, which has the less dimensionality than the raw data space, is constructed from the principal components of a large number of ultrasonic sensors data sets. Subsequent ultrasonic data sets from the environment project as a point in this principal components space. By application of BP neural network and SVM (support vector machine) method respectively, these projections are classified into typical local structures of the environment in order for the robot to discriminate them. Fifthly, this dissertation describes a behavior-based reactive navigation architecture for mobile robot working in unknown environment. The navigation control architecture for the mobile robot is reactive architecture that composes of several behavior-based modules such as move_to_goal， follow_wall，avoid_obstacle and emergency_brake. Each behavior module can decide its own output according to the sensors’ inputs and the restrain to lower behavior layer by upper behavior. The simulation and experiment results are provided to demonstrate that the proposed method provides an efficient way for mobile robot navigation in unknown environment. Finally, the obtained research results are summarized and future work is addressed.
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