Path Planning Of Mobile Robot In Unknown Environment

Mobile robot is the system which includes the environment sensation, the localization and the control method. It mainly involves many disciplines, such as the machinery, the electron, the computer and the automatic control. It becomes one of the hottest topics in the present research. Now, mobile robot is being widely used in many aspects, such as the military survey, the path examination, the warehouse transporting, the intelligence living and the entertainment.The sensation of the system is mainly composed of the ultrasonic sensor and the electronic compass. It provides the distance of the obstacle around and the direction information. Because the ultrasonic wave has strong echoing characteristic, the system adopts time-transition method to measure the distance. The direction of the robot is estimated by the electronic compass based on the the second harmonic component. Disposing the ultrasonic sensor and the electronic compass reasonably in the different position of the mobile robot, the system measures the environment constantly. As the ultrasonic wave has bad directive property, the information needs to be fused. And according to the fusion result, the system divides the environment into two types:the obstacle mode and the non-obstacle mode.At present, one of the most driving mechanism is the differential two-wheeled mobile robot. It has the simple structure and the fast response, and it is easy to be controlled. This article analyses this organization's kinematics model and the localization algorithm——dead reckoning. It is benefit for the robot to travel in unknown environment.As it dosen't need to establish the mathematical model and it has strong adaptiveness and robustness, the fuzzy control is often used in mobile robot control based on the behavior. The PID algorithm is simple, but it is difficult to achieve higher precision and smaller overshoot for the nonlinear and the time-varing system. The fuzzy adaptive PID control can change the PID parameters online for the environment, and it has strong adaptiveness and robustness. This article theoretically analyses the fuzzy control and the fuzzy adaptive PID control algorithm, and proposes that the fuzzy control is used for the obstacle mode and the fuzzy adaptive PID control is used for the non-obstacle mode.However, as a result of control algorithm's limitation, the mobile robot will be unable to realize the behavior successful when it meets the extreme environment. This article discusses the "U" trap and the target nearby the obstacle's question. These question can be sovled by the method of "virtual target point" and " enlarge distance "Finally, this article elaborates the architecture of the system, and analyses the principle of the simulation platform based on the MATLAB GUI. This passage simulates the control method of the mobile robot and explains the simulation result reasonably. The simulation results indicate that the system has quick response speed and strong robustness, and can realize the safe track from the beginning to the static target point under the non-structural unknown environment.