Research On Control Of Multimodal Cable Driven Astronaut Training Robot

The Earth is the cradle of mankind,but we will never live in the cradle forever.Major countries have paid much attention to the manned space flight as it plays an important role in extending the activity space for human beings and promoting comprehensive capability.Besides,aerospace projects are of great importance in developing human civilization,promoting social progress,and strengthening the soft powers such as national cohesion and scientific culture.However,the manned space flight is limited by adverse elements including the outer space environment,aircraft,additional elements caused by high speed,and the complex exoplanet environment,etc.Amongst those negative factors,micro gravity has the most effect on the health and work of the astronauts,it even endangers their lives for its long time and lasting impact.By simulating the load characteristics of the gravity environment through parallel cables robot and load the force on human body,the multimodal astronaut training robot(MAT)can realize multiple physical exercises including running,bench press and deep squat,which can help the astronauts to alleviate the adverse impact caused by the space adaptation syndrome(SAS).Therefore,MAT is meaningful to the manned spacecraft development.This dissertation is supported by the National Natural Science Foundation of China under grant No.61175128(Research on Astronaut-Rehabilitation-Training Robot under Space Micro Gravity Environment).The current training devices for astronauts have problems such as singular function and unsatisfactory training effect.With the aim to solve these problems,this dissertation tries to help astronauts perform multiple training exercises in microgravity environment by the parallel cable robot,and conducts theoretical and experimental research in details within aspects including robot configuration,mathematical model of the cable driven unit,control strategy,and human-machine system control strategy.Firstly,both the trend and obstacles of the manned space flight's development will be analyzed.Precautions for the SAS will be outlined as well.In discussing the causes of the SAS,training patterns and training mechanisms of running,bench press and deep squat are to be confirmed,and the design requirements of the robot will also be put forward.According to design requirements,a modularized and reconfigurable robot structure and a cable driven unit structure are to be brought forward.The controllable work space and safe work space of the robot will be confirmed after the configuration optimization,and the overall control scheme is designed in accordance with the structure and operating requirements of the robot.Secondly,with the modularized cable driven unit being the research object and takes the motion impact of the carrying object into consideration,this dissertation constructs a complete mathematical model for the passive force servo system of the cable driven unit.A nominal parameter model of the system in line with the mathematical model is put forward.The analyzing of uncertain factors in the system and the influence of each factor provide the basis for system improving.Models of cable,forward channel and surplus force will be identified by experiments,and the experiments will also demonstrate the veracity of the system model.Thirdly,for solving the control problem in designing MAT,an active hybrid control strategy and a nominal model of the cable driven unit are designed based on the passive force servo system control characteristics of cable driven unit.The simulation and experiments show that the system after the hybrid correction has acceptable stability,high steady state accuracy,and good dynamic quality,and it can satisfy the double ten index.A passive load control strategy of the cable driven unit is to be designed based on the theoretical analysis and experimental research on the generation mechanism of the surplus force.The simulation and experiments are used to test the cable driven unit's effects in reducing the surplus force,and to test the quality robustness of the system.Fourthly,dual closed loop control strategy of MAT will be designed with the man-machine system of MAT being the research object.The loading precision of each cable driven unit is improved by the inner loop passive hybrid force controller,and the overall loading precision is improved by the outer loop loading force controller.By building up mathematical models of cable traction for running exercise,bench press and deep squat respectively,the mathematical relationship between the tension,length and expected load force of each cable is confirmed.The dynamic models in the microgravity environment of running exercise,bench press and deep squat are built based on the lagrangian method.Thereafter,a man-machine simulation model will be constructed by the MATLAB toolbox.The simulation results will testify the accuracy of the cable traction model of the robot,and assess the effectiveness of the dual closed loop force control strategy as well.At last,based on the dSPACE semi physical simulation platform and the modularized prototype of the cable driven unit,the experimental prototypes with different configuration will be combined,and experiments will be performed to assess single cable driven unit performance,planar dual cable driven unit performance,triple cable driven unit performance,and man-machine research.The results will verify whether the configuration of MAT designed by this dissertation is reasonable,whether the cable traction model is accurate,whether the control strategy is effective,and to verify that the MAT can assist the physical training of astronauts who live and work in the microgravity environment.