  The paper presents advancement of the matrix structural analysis technique
(MSA) for stiffness modeling of robotic manipulators. In contrast to the
classical MSA, it can be applied to both parallel and serial manipulators
composed of flexible and rigid links connected by rigid, passive or elastic
joints with multiple external loadings. The manipulator stiffness model is
presented as a set of basic equations describing the link elasticities that are
supplemented by a set of constraints describing connections between links.
These equations are aggregated straightforwardly in a common linear system
without traditional merging of the matrix rows and columns, which allows
avoiding conventional manual transformations at the expense of numerical
inversion of the sparse matrix of higher dimension.
