Structual Design And Optimization Of Compact High Torque Robot Joint

On-orbit service is a key field of space technology development.On-orbit service includes rendezvous and docking,on-orbit assembly,on-orbit maintenance and so on.With its good task adaptability,the space manipulator has been a great application on on-orbit service.In this paper,a task of on-orbit assembly and a scheme of using 9-DOF manipulator is proposed.And based on this task,a compact high-torque modular robot joint for space manipulator was designed.First of all,the on-orbit assembly task is analyzed.According to the task analysis result,the design index related the 9-DOF manipulator is decided.Then the parameters and functional requirements are also decided based on the former design index.Second,according to the design parameters of joints,through the calculation and access to product manuals,the selection of joint parts are completed.After the selection of the joint parts,the detailed design of the compact high-torque modular joints is done based on the joint parts.Third,according to the two typical stress states of the manipulator,the finite element analysis of the joint model is carried out on the joint model and the weakness of the joint model is found out.The analysis results show that the stiffness of the harmonic output shaft is insufficient and the stress concentration exists in the alignment hole in the joint model.The stiffness of the upper and lower extension plates is also insufficient.Then,according to the results of the analysis,the harmonic output shaft and the joint shell are optimized.The finite element analysis of the modified joint model shows that the maximum stress of the harmonic output shaft is decreased by 40%,the stiffness is increased by 28.8% and the deformation of the joint plate is decreased by 28.9%.The above results show that the effect of our improvement measures is significant.Finally,we designed an output torque of 150N·m cycloid gear reducer.In order to reduce the volume,the cantilever rollers are changed into rollers in the semicircular grooves.According to the new structure,a cycloidal reducer is designed.Then,the objective function and the boundary condition of the new cycloidal pinwheel planetary reducer are deduced according to several important parameters of the cycloidal reducer and the structural characteristics.Then the reducer is optimized through the objective functions and the boundary conditions by using the genetic algorithm tool of MATLAB Box.And finally,the finite element analysis is to verify whether the structural strength to meet the requirements.