Path Planning And Path Following For Mobile Robot In Unknown Environment

In this paper,the path planning and path following of mobile robot in unknown environment through the actual mobile robot platform are studied.The specific research contents are as follows:Firstly,in order to provide a reliable experimental platform for the research problems,the system platform of wheeled mobile robot is set up,and the overall scheme is designed on the platform,including the construction of the framework of the hardware and software of the robot,the selection and configuration of the required sensors,and the design of the underlying motion control system.Secondly,in order to realize the path planning of mobile robot in unknown environment,a path planning algorithm which combines the rapidly exploring random trees(RRT)algorithm with the rolling window in the field of vision is proposed.The method extracts local environment information in rolling window in real time,and adjusts the horizon of rolling window adaptively according to the change of environment.Through the analysis of the information obtained by the sensor in the rolling window,the feasible path is screened out with the proposed algorithm to control the mobile robot to reach the target point.In this process,the planned path is dynamically monitored to ensure that the path is reasonable,and the above process is repeated until the target area is reached.The experimental analysis shows the feasibility of the method.Thirdly,for the wheeled mobile robot is a differential system,it needs a smooth and stable trajectory.Three times Bezier curves are used to smooth the results after path planning.According to the path obtained by the path planner,in order to make the smooth curve path safe and feasible,a series of restrictive conditions of the experimental platform are obtained through several experiments,and then a series of two programming(SQP)method is used to solve the optimization problem,and the Bezier curve path equation is obtained.Experimental analysis shows that the curve path is smooth and stable.At last,a following path is parameterized to make the mobile robot track the expected path which does not take time as reference.The initial coordinate system is established at the initial position of the mobile robot.The path coordinate system is set up with the expected point that the robot needs to be tracked on the desired path,and the error between the actual position and the expected position is calculated in this coordinate system.Then the updating law of the parameterized path and thecontrol law of the path following are derived.In order to make the tracking error converge,the selection of control parameters is given.Considering the situation of mobile robot's non-stop motion,the strategy of early control is adopted to reduce the error of the robot near the sub target point.Experimental analysis shows the feasibility of the method adopted.