A comparison of stiffness analysis methods for robotic systems

A robotic structure consists of a kinematic chain composed by links that can be rigid or flexible, interconnected by joints. One of the outstanding problems in robotic design and operation is to estimate a robot behaviour under the action of external loads. In particular, it is needed a standard procedure to obtain the stiffness performance through the whole robot workspace. This paper presents a review about the main available methods to calculate the robotic systems stiffness performance in terms of a local Cartesian stiffness matrix. Specific attention is addressed to methods based on lumped parameters both by using the kinematic and dynamic forces distributions and by using Jacobian matrices. This paper also describes methods based on matric structural analysis (MSA) and finite element analysis (FEA). Two cases of study have been reported to analyse and compare the above mentioned methodologies for providing a suitable mean to choose the most appropriate method for a given application.