摘要：Parallel manipulators have many advantages over serial manipulators in termsof high load/weight ratio, velocity, stiffness and precision. A dimensional design theory andmethodology of six degrees of freedom scissor parallel manipulator (SPM) is investigated. The SPMkinematics inverse equation is given. Based on the formulation of the local dexterity and thedefinition about the indexes of workspace incircle radius, the effects of the design parameters onthe dexterity and workspace are discussed. Moreover the incircle radius change ratio about workspaceare defined and used as the evaluated indicator to analyze the effects of the design parameters onthe performances. A dimensional design theory that could satisfy the requirement of dexterity andworkspace is proposed. The dimensional design theory and methodology can be of help in the design,trajectory planning and control of parallel manipulator.

摘要：The design theories of the ballastless track in the world are reviewed in comparison with the innovative research achievements of high-speed railway ballastless track in *** calculation methods and parameters concerning train load,thermal effect,and foundation deformation of high-speed railway ballastless track,together with the structural design methods are ***,some suggestions on the future work are provided.