Research On Space Station Manipulator Aided Safe Path Planning For Astronauts

When the space station mechanical arm assists the astronauts to complete various tasks,it needs to assist the astronauts to move and ensure the safety of the astronauts,that is,there can be no collision in the process of movement.The space robotic arm assists the astronauts to plan the safe path,which is the main research content of this topic.The space station manipulator is a seven-degree-of-freedom redundant manipulator.With a redundant degree of freedom,the space manipulator is more flexible and can achieve more functions such as obstacle avoidance.In this paper,the following research works have been done for the space manipulator.Auxiliary astronaut safety space manipulator path planning the first step to determine whether target points and path within the manipulator workspace,judgment methods directly on the terminal position inverse solution,the inverse solution existence means that if the terminal position at work within a work space,otherwise,illustrates that point are not within the working space of manipulator.Based on the kinematics model of the 7-DOF manipulator,the position level inverse solution of the space manipulator is studied.In order to more quickly to find the terminal position after corresponding to each joint Angle and studied the mechanical arm space manipulator inverse velocity stage,the first to use the simplest pseudo-inverse method,but the pseudo-inverse method of inverse solution is too large,there will be a joint speed in turn introduce damping coefficient improvement of damped least square method,but after the introduction of damping end tracking accuracy is reduced,So the negative feedback thought is introduced and the damped least square method after the negative feedback thought is introduced shows a better effect.Collision detection is the most important part of the safe path planning assisted by space manipulator.This topic adopts the collision detection based on the bounding box.Because the arm of space manipulator,all parts of the space station and astronauts are cylindrical or similar cylindrical,in order to facilitate and fast collision detection,For space manipulator arm,and each part on the crew capsule body collision model,collision detection when only the capsule to check whether the intersection,you can determine whether the parts collision,this paper studies the space of two capsules fast accurate intersecting detection algorithm,through the enumeration space of the relative position of two capsules,Find the calculation method of the minimum distance between two capsules so as to judge whether the two capsules collide.Path planning method based on the collision free path planning algorithm of RRT algorithm,and some of the problems of RRT algorithm,based on RRT algorithm is improved,and joined the probability to select target respectively sampling and regression filter mechanism for RRT algorithm based on target and the introduction of filtering mechanism of regression RRT algorithm is better than the standard RRT algorithm,The improved RRT algorithm can search the collision-free path faster and more efficiently.Finally,a semi-physical model simulation experiment was designed,and several groups of experiments were compared to verify the effectiveness of the proposed safe path planning method.