Reserch On Multi-joint Repairing Manipulator's Obstacle Avoidance Path Planning

Avoidance obstacle path planning problem is able to be stated as follows:in obstacles environment,based on a certain evaluation criterion(such as the shortest length of path,the shortest time of moving,the minimal consuming of energy,and so on),from start point to destination point,plans a optimal(or sub-optimal)collision free(obstacle avoidance)path.Kinematics of manipulator is the foundation of path planning to avoid obstacle, firstly, kinematics model was established in the paper, inverse kinematic problem-solving is relatively complicated, because in essence it is a settling nonlinearity equation problem, there is no universal method yet. According to the low redundancy, limited working environment of the manipulator, a simple and easy to apply method of a kind of geometry diagram method which is simple and easy to apply is given, and the simulation of the kinematics of the manipulator is verified in VC++ simulation platform.When the manipulator is repairing, how to judge and avoid collision is the prime of automatic operating. A method named network bounding based on bounding box and equivalent cylinder is proposed, and the areas that might collision has been systematic analysised, by decomposing spatial local field effectively,simple and effective geometry equivalent,we transformed the manipulator's collision detecting to the solution of space analytic geometry, greatly simplifies the problem.Robot collion-free path planning has not be well resolved until now, especially for the robot collion-free path planning in 3D space is more difficult. For probabilistic roadmap method has the characteristic that is easy to realize, has good generality, especially the effectiveness in solving multi-degree of freedom robot path planning,it causes researchers' attention in recent years. This paper adopts normal probabilistic roadmap method to get a roadmap which expresses structure information in configuration space,tests connective relation between each milestone in advnce to get a connected roadmap.When in actual path planning ,at first to find out the nearest two milestones to the starting point and the target point, and then by the use of heuristic searching method to search the connected roadmap to find out a path connected the two milestones,that is the wanted path.Based on comprehensive analysis of path planning , to improve the real-time performance,we adopt bi-directional search based on greedy collion detecting to plan the manipulator's motion in real time .This method has the following characteristics:do not need to compute the roadmap in advance,thus saved a lot of precomputation time; bi-directional sampling, to establish the roadmap by gradually increases the two landmark trees which root are the input query configurations, the two trees alternate sampling can keep the two tree balance;greedy collision detecting,delay the collision detection until definitely needed,which can save the planning time.Finally , we carryed out simulated operation separately aiming at the concrete path planning problem,the result show that the method we used can well resolve the running stability and controlling real-time quality when the manipulator works.