Research On The Workspace And Trace Planning Of A New3-PCR Parallel Robot

Parallel robots possess many advantages such as high stiffness, high precise, compactconstructure,fast respond of dynamic and so on. German senior engineer Steward designed aplatform called ‘Steward Platform’ in1965.Since then,parallel robot derived from ‘Steward’attached a wide range of research.But parallel robots with6DOF have disadvantages,such asstrong coupling,small workspace and so on,and this limited the application of parallel robot.On many occasions, limited DOF parallel robots possess some advantages comparing with6DOF parallel robots,including greater workspace,weaker coupling,less drivers than the oneswith6DOF,and are attaching a wider arrange of research and application.The research on the3-PCR parallel robot is introduced in this thesis after referring to therelated documents and materials both at home and abroad.This paper invests the workspaceand trace planning of3-PCR parallel robot.Based on the3-PCR parallel robot kinematics equations, according to the correspondingconstraint equations, its workspace was abtained via geometrical method,and the workspaceabtained was verified by solving its workspace via searching method in Matlab.Then thevelocity jacobin matrix of the robot was analyzed and its workspace singularity wasdisscussed.Given3-PCR parallel robot joints geometric parameter,through changing one ofparameters, the law of parameters’ influence on workspace was concluded by observing thechange of workspace.Analyzing the3-PCR parallel robot’s the expression of inverse solution, the reason ofowning sevral solutions was discovered.In the simulation of model in ADAMS, the singlesolution of a3-PCR was abtained in workspace.By using geometrical method,given drivers’displacement, it is learned that3-PCR parallel robot in certain conditions have servralsolutions.When adding constraint equations,it possesses single solution.Through searchingforward solution of3-PCR parallel robots in workspace via iteration searching method,forward solutions were abtained, and that verified the3-PCR parallel robots possess singlesolution under given constraints.In the workspace obtained and the forward,inverse solutions, the research on traceplanning of3-PCR parallel robots was discussed based on the expression of inversesolution.Through analyzing the lines of drivers’ displacement,velocity,acceleration, it’slearned that the lines were smooth without bumps.Based on forward solutions of3-PCRparallel robot, the trace of the moving platform was abtained, the changing of drivers’displacement was equal and no bumps.Through the comparison of the two methods of planning trace,it’s learned that: the traceof a3-PCR parallel robot planning based on inverse solution could make moving platformstrictly according to the given trace;that based on forward solution couldn’t,but could makethe moving platform movement more efficient.