This paper extends the kinematic manipulability concept commonly used for serial manipulators to general constrained rigid multibody systems. Examples of such systems include multiple cooperating manipulators, multiple fingers holding a payload, multi-leg walking robots, and variable geometry trusses. Explicit formulas for velocity and force manipulability ellipsoids are derived and their duality explained. The concept of unstable grasp and manipulable grasp are also extended and illustrated with examples. It is then show that manipulability can be significantly modified through bracing with another arm. Finally, several methods for comparing manipulability ellipsoids are developed which can be used in turn to optimize the brace design.
in Complex Robotic Systems, Ed. by P. Chiacchio & S. Chiaverini, Springer-Verlag, London, U.K., 1998. pp.33–78.