Research On Global Optimization Of Fault Tolerant Trajectory For Space Manipulator

As a typical on-orbit operation tool,space manipulator can greatly assist or substitute the astronaut to complete heavy space tasks.The joint failure of space manipulator is likely to appear during its long-time service,considering the hostile space environment and the complexity of the joint structure.Once the joint of space manipulator fails,it is usually unable to be repaired in time and the maintenance cost is huge,which will lead to the delay of space tasks or even affect the implementation of the space program.Therefore,in order to guarantee the ability of space manipulator to complete the space tasks continuously the space tasks after locking the fault joint,it is meaningful to research on the theory of fault-tolerant motion control on the condition of locking the fault joint.Aiming at improving the fault tolerance performance of the space manipulator,the fault tolerant performance evaluation of the terminal trajectory,the solution of the joint space fault tolerant configuration,the global optimization of fault tolerant trajectory constrained by multi-constraints and multi-objectives are studied in this paper on the condition of single joint failure.The effectiveness of the research is verified by simulations.The detailed research content includes the following aspects:Firstly,the reliability fault tolerant workspace and the task directional degradation manipulability measure are established to describe the fault tolerant performances.The fault tolerant performance evaluation strategy of terminal trajectory for space manipulator is proposed based on the reliability fault tolerant workspace.The advantage and validity of the research above is verified by simulations.Secondly,the solution of joint configuration collection for the given terminal trajectory sequence points is discussed.By introducing the fault-tolerant performance evaluation criterion and its mathematical description,the solution of fault tolerant joint configuration group which is corresponding to terminal trajectory sequence points is proposed and the correctness is verified by simulations.Then,the problem of connecting the discrete fault tolerant configuration group is solved by using the joint trajectory planning based on polynomial interpolation.Considering the joint angle limitations,obstacle avoidance as the constraints and the task directional degradation manipulability,energy consumption as the optimization goals,the global optimization model of fault tolerant trajectory is established.By using the multi-objective particle swarm optimization algorithm,the global optimization of fault tolerant trajectory constrained by multi-constraints and multi-objectives is accomplished and Pareto optimal solution is achieved.Finally,an air float space manipulator ground experiment platform is used and a 3D simulation system that suits to the experiment platform is established.The experiment project according to the research content of this paper is designed and the effectiveness of the global fault tolerant trajectory optimization theory is verified by 3D simulations and the experiments.