Generalized center of compliance and stiffness

The elastic characteristics of many robot systems can be modeled by a 6*6 stiffness or compliance matrix. Three results are presented via screw theory. First, stationary values of compliance and stiffness are determined. Second, linear and rotational properties are characterized by dual ellipsoids in three-dimensional space. Third, a generalized center-of-elasticity (compliance and stiffness) is proposed. If a compliant axis exists, it is shown to pass through the center. These elements simplify the understanding of complex elastic properties.<>