Research On Localization And Motion Control For Outdoor Mobile Robot

In the research about mobile robots, autonomous navigation is the key issue of mobile robots. It reflects the autonomy and intelligent level of mobile robots. And in order to complete the navigation task, it must solve the following four questions: motion control, world modeling, path planning and localization. This paper mainly studies the localization and the motion control about outdoor mobile robots.Location is an important part in the mobile robots’ navigation control. As a fundamental part of the robot navigation, robots first need to identify their own posture in the two-dimension or three-dimension working space on the global coordinates, and then can carry on the follow-up action of navigation. The mobile robot in this paper will navigate autonomously in the environment surrounding with buildings and trees. According to the characteristics of its working environment, the combination of Real Time Kinematic GPS(RTK-GPS) and Odometer is used in the navigation localization. The signal of RTK-GPS is very easy to be influenced by external environment. The odometer using the method of dead reckoning with high positioning accuracy in a relatively short time, but with the increase of time, the cumulative error will gradually increase. The two kinds of location methods have their own advantages and disadvantages. So in this paper, for improving positioning accuracy, it uses the Extended Kalman Filtering method to fuse the data of Odometer and GPS. In the method of EKF, the model of system state error and the model of observation error model has a great influence on the final data fusion. In order to obtain a better fusion effect, this paper analyzes the error model of odometer and GPS, and design method to determine the quality of GPS positioning data. Experiments have been carried out to verify the data fusion algorithm. The results verify the effectiveness of the localization algorithm.Wheeled mobile robot is a kind of typical non-holonomic constrained nonlinear system. It’s not easy to complete its motion control. In this paper, the trajectory tracking problem of mobile robot motion control is studied. According to the dynamics model of mobile robots, global trajectory tracking controller is designed. By using the method of Backstepping, the continuous time variable trajectory tracking controller is designed by selecting the appropriate Lyapunov function, and it is proved that the closed-loop system is globally uniformly asymptotically stable. Then, the simulation analysis of the influence of controller parameters on the tracking performance. he simulation results show that the designed controller has good tracking performance. Through experiments in the real environment, the validity of the controller is verified in the actual work.