Design Of The Reducible Translational Parallel Mechanisms

Coupling, which exists in almost every system, is the essential reason of conflict.For the parallel mechanisms, the coupling of various motions, every performance indicesmakes the type synthesis, dimensional design, performance increasing and control systemdesign very complicated. This thesis aiming at the coupling problems of parallelmechanisms, the type design methods of parallel mechanisms whose motions aredecoupled will be proposed. The main content includes:(1) The research and applications of parallel mechanisms are reviewed. The existedtype synthesis and design methods of parallel mechanisms are summarize and theproblems in them are also presented. The significances and main work of the research onreducible parallel mechanisms are proposed.(2) The definition of general reducible system is presented. The conception of thereducible parallel mechanisms is presented. The reducible character of the motion andstatic functions of parallel mechanism are classified.(3) The determinate condition for 3-DOF reducible translational parallelmechanisms are defined and proved. A new coordinate is given and the type synthesismethod of 3-DOF reducible translational parallel mechanisms is presented. Some parallelmechanisms are synthesized by the method. The relationship between the reducibility ofthe mechanism and the configuration of the limbs is discussed.(4) The reducible mechanisms are grouped into two classes according to theirdriving methods. The motion performances are discussed. The excellences anddisadvantages of the mechanisms are discussed.(5) The static indexes of the two groups of reducible mechanisms are discussedrespectively. The stiffness model of each mechanism is set up.(6) An optimum design is carried through based on the workspace. The parametricrelationship between the dimensions of components and the driving parameters are set upby investigating the structural, motional and interference of the parameters. Theparametric optimum design reduces the numbers of the design parameters.(7) The optimum design is carried through based on the stiffness. The methods toincrease the stiffness are also proposed.