A Numerical Modeling Study of the Effects of Various Joint Boundary Conditions on Stiffness Behavior of 6DOF Platform's Top Plate

Simulation driven designs are used for the efficient development of high precision devices such as parallel manipulators/platforms. Accurate prediction of these simulations depends upon the fact that how closely actual conditions are incorporated in the analysis. Stiffness is a key property for parallel platforms as it dictates the positional accuracy of the system. Overall stiffness of the platforms is not only driven by the stiffness of the links but also by contact stiffness of joints. Heavily loaded platforms present a special case as these are more prone to system failure if not designed properly. In this work, the stiffness behavior of 6-DOF platform's top plate subjected to various boundary conditions at joints have been analyzed. Different boundary conditions i.e. volume at joints, surface at joints and line at joints, has been used to depict real joint behavior. The stiffness of platform is analyzed for each of these cases independently and comparison of simulation results for every condition is presented both for static as well as dynamic conditions. This comparison presents a useful outcome for better prediction of static stiffness behavior and dynamic response thus aiding in more accurate design of such applications.