Research On Characteristics For3-RPR Three Degree Of Freedom Parallel Mechanisms

The parallel mechanism is a kind of robot structure which enjoys the advantages ofrigidity, speed, high accuracy, and large load carrying capability. Six degree of freedom robotshave been studied adequately and been used in many engineering domains. Nowadays, lowmobility parallel robots have drawn a lot of interest in the area of robot because of its low cost,simple structure and suitablility for many situation that requiring low mobility parallel robots.In this dissertation, Taking3-RPR parallel robots as the object of study, such items are studied:position analysis, singularity analysis, workspace analysis and stiffness analysis.According to the position analysis of3-RPR planar parallel mechanism, kinematicequations, inverse kinematics and the forward solution of position are derived. Thedisplacement, velocity and acceleration curve are obtained by use the UG software for motionsimulating. According to the kinematic equations, the Jacobi matrix is derived and theworkspaces of the mechanism are obtained.The Three kinds of singularity of the mechanismcan be obtained by the Jacobi matrix and Gosselin defined three kinds of singularity ofmechanism. Then analysis how the pose angle, the moving plateform and the fixed plateformaffect the workspace of the machnism.The dissertation deduces the analytical stiffness equations of the3-RPR planar parallelmechanism and new conservation stiffness matrix. The MATLAB software are used instiffness mapping, combine the stiffness character and the workspace of the parallelmanipulator is analysis in detail. The final results show that the stiffness of the3-RPR planarparallel mechanism is configuration dependent, and proportional to the actuating forces andjoint stiffness. The stiffness of the mechanism not only relates to the size of the actuatingforces, but also their direction. The stiffness has some certain symmetrical relationship for the symmetrical mechanism.