Design Of Harmonic Reducer Used In Joints For Space Manipulator

As the successful docking of TianGong1with the series of the shenzhouspacecraft and the rapid development of the space technology, the spacemanipulator which plays an important role in the space station becomes veryimportant to people gradually. The joints is an important part of manipulator. Theperformance joint will impact the quality of job by space manipulator directly. Sothe joint demands the special requirement for the mechanical drive. Since thestructure is complex in joints, puting the wire through the axis hole of the joint willprotect the wire itself and save the space.As the axis hole in general harmonicreducer is very small, this subject aims to develop a harmonic reducer with a certainsize, large aperture of axis, big drive ratio, good transmission precision, largestiffness, and long fatigue life used in manipulator joints.First of all, the right tooth profile and drive ratio were choosed according to theresearching condition. Then the meshing parameters such as modificationcoefficient and modification for height of tooth were calculated. Then the conditionof normal transmission without interference was verified. After the basictransmission size such as reference circle was designed, the size of flexible gearpreliminary and test wear of tooth surface, fatigue strength, the bottom stabilityof flexible gear were designed too.Then the size of flexible gear was optimized. Flexible gear is short in life ofharmonic reducer. Reducing the alternating stress in flexible gear during working isthe main goal of the optimization. The influence in the flexible gear by structureparameters such as the corner and wall thickness of flexible gear were analysisedwith the finite element tool ANSYS. Then the size of flexible gear was optimizedbasis on the stress.The circular spline and wave generator were designed after the size of flexiblegear were designed. The overall and aperture size meet the design requirements well.Then the stiffness analysis model was established and simplified, so that thestiffness curve was got. The stiffness by simulation was compareed with theexperimental results to analyses the reasons of difference. The fatigue life wasanalysised by ANSYS, then the influence in fatigue life of the flexible gear under the action of different torque was got.Finally, the performance of harmonic reducer was tested. After cleaning andchecking the harmonic reducer, the no-load and load running experiments werecompleted. Then the returning difference, and transmission accuracy of harmonicreducer by the theory of optical measured. At last he stiffness experiment by loadingwas completed,so the mechanical hysteresis curve and the stiffness of harmonicreducer was got.