Normal forms of stiffness and compliance matrices

A generalized spring associates potential energy with each position and orientation of a rigid body. The stiffness of such a spring can be represented by a 6 × 6 symmetric matrix. This matrix can be brought to a normal form by a particular choice of the coordinate frame. Analogous but independent results hold for compliance matrices. These results, obtained by using a Lie group approach, also extend the concept of the remote center of stiffness to generic generalized springs.