Research On The Motion Planning System Of Space Manipulator For The Full Cabin Care Of Space Station

The operational life of the space station in orbit will exceed ten years,and maintenance work outside the cabin is inevitable.Due to the complex and harsh space environment,the care and maintenance work of the space robotic arm execution module is more safe and cost-effective.The distribution of extravehicular care points throughout the entire cabin of the space station requires the robotic arm to switch adapters multiple times for large-scale crawling transfer during task execution.The generation of its motion trajectory is a key issue in task planning.At present,the generation method of robotic arm crawling transfer trajectory is for ground operators to select adapter switching sequences and subtask trajectories based on experience.This process is difficult to operate,requires high technical requirements,and incurs high labor costs,resulting in a lack of scientific motion trajectory generation.Therefore,it is of great practical significance and engineering value for the long-term and reliable operation of the space station in China to carry out research on the autonomous generation method of the motion trajectory of the manipulator for the whole cabin care task of the space station,and to develop a space manipulator motion planning system for the whole cabin care task of the space station.This article conducts research on the optimization strategy for the care configuration of space robotic arms,the optimization strategy for multi adapter switching sequences,and the task planning method between adjacent adapters.The specific research content is as follows.Firstly,the analysis and design of the space manipulator motion planning system for the whole cabin care of the space station are carried out.Analyze the motion process of the robotic arm performing cabin care tasks and abstract it into two stages,namely the optimization of the robotic arm care configuration and the optimization of the robotic arm multi adapter switching path;Analyze the functional requirements and performance requirements of the space manipulator motion planning system,and determine the positioning,functions and objectives of the system;Based on the above analysis and design,the overall architecture of the system and the architecture of each functional module provide a design basis for the subsequent development of the space manipulator motion planning system for the whole cabin care of the space station.Secondly,to address the issue of the non uniqueness of the robotic arm care configuration and adapter when the care point pose is fixed,a strategy for optimizing the care configuration of a space robotic arm is studied.Based on the analysis of cabin care task types,establish performance evaluation indicators for optimizing the configuration of robotic arm care;Aiming at the constraint conditions of fixed posture of care points,the optimization problem of care configuration is transformed into a zero space configuration optimization problem of robotic arms,and an optimization model is established;Based on the NSGA-Ⅱ algorithm,a configuration optimization strategy for space robotic arms is designed to solve the problem of unknown mechanical arm adapters and reference configurations,and the algorithm is prone to falling into local optima,achieving optimal care configuration optimization and adapter optimization for space robotic arms.Thirdly,in order to achieve autonomous generation of the motion trajectory of the robotic arm from the initial configuration to the care configuration through multiple adapters,a multi adapter switching path optimization strategy for space robotic arms is studied.The strategy is divided into two stages,namely,optimizing the switching sequence of multiple adapters and planning the task of robotic arms between adjacent adapters;To address the optimization problem of multi adapter switching sequences,a space station adapter network topology diagram is established,and the selection of multi adapter switching sequences is achieved based on breadth first search algorithm;The task planning problem of robotic arms between adjacent adapters is divided into task overall planning and obstacle avoidance strategy planning;The overall task planning is based on the state space planning method to decompose complex tasks into subtasks;Obstacle avoidance strategy planning is based on the improved D*algorithm to decompose subtasks into robotic arm motion trajectories.The experiment shows that the improved D*algorithm accelerates the running time by 30.44 times and the multi adapter path optimization algorithm can achieve autonomous generation of robotic arm motion trajectories.Finally,based on the analysis and design work of the space manipulator motion planning system and the above algorithm,the space manipulator motion planning system for the whole cabin care of the space station is developed,and the overall system experiment is designed and carried out to verify the engineering value of the system in supporting the good operation of the space station on orbit and generating the movement track of the whole cabin care of the manipulator independently.