Research On Location And Path Planning Alorithms For Outdoor Mobile Robots

Realize the accurate positioning,fast and accurate navigation of the outdoor mobile skid-steering robot has always been hot research area.This paper takes the outdoor skid-steering robot as the research object,aiming at the problems that the current equipment and algorithms are difficult to achieve smooth global positioning,can not plan a smooth global path with kinematic constraints,and the speed and accuracy of trajectory tracking are not high,the global positioning,global path planning,local path planning and trajectory tracking algorithm of outdoor skid-steering robot.This paper focuses on the global positioning algorithm adapted to the kinematic characteristics of the skid-steering robot,the graph search global path planning algorithm based on motion primitives and the improved dynamic arc fitting trajectory tracking algorithm.The main work is as follows1:Research on global localization algorithm of outdoor mobile robot.In this algorithm,Kalman filter is used to optimize the attitude of the robot.The state prediction of Kalman filter is realized by using uniform motion model and uniform acceleration motion model respectively,and then the filtering processing of robot positioning is realized.By comparing the positioning effect of the two methods,the final positioning scheme is determined.2:Research on global path planning algorithm based on motion primitives.The algorithm uses graph search algorithm based on motion primitives to make the planned path conform to the kinematic constraints of the skid-steering robot.The algorithm uses the reverse incremental search algorithm to realize the fast replanning.The dubins curve close to the target is added to realize the path stitching.In order to speed up the search speed,the methods of enlarging heuristic coefficient and limiting the search scope are adopted.3:The dynamic obstacle theory and the global path graph search algorithm based on motion primitives are combined to realize the multi robot path planning which conforms to the kinematic constraints of the skid-steering robot.4:Research on trajectory tracking algorithm based on improved dynamic arc fitting.In order to improve the tracking speed and accuracy of skid-steering robot,an improved dynamic arc fitting trajectory tracking algorithm is proposed to solve the problem of poor global path fitting.The algorithm formulated a dynamic forward detection distance model,which can dynamically cut off the path at the points which the heading angle change drastically.In addition,the obstacle potential field model with the trajectory collision detection equation is considered to ensure the safety of the fitted trajectory.The average arc radius model,uniform change of arc radius model and hard constraints of attitude adjustment range are formed to improve the moving speed and stability of the robot.Furthermore,a prediction and compensation model of slip error are modeled to reduce the trajectory tracking error.5:Experimental study.The platform of skid-steering robot is built,and the software of positioning and path planning is written.The effectiveness of the algorithm is simulated and tested.