A Variational Principle for Quasistatic Mechanics.

Abstract : Quasistatic mechanical systems are those in which mass or acceleration are sufficiently small that the inertial term ma in F = ma is negligible compared to dissipative forces. In robotics quasistatic mechanics may be used for systems with friction when motions are sufficiently slow. Here consider a general quasistatic system with constraints and both dissipative and conservative forces. Under some conditions it is possible to replace Newton's law with the simple and intuitive variational principle that the system moves within the space of unconstrained motions, in such a way as to minimize power. For quasistatic systems this 'principle of minimum power' is correct if all the 'velocity dependent' forces are parallel to the velocity and have a magnitude independent of velocity, i.e., are essentially equivalent to Coulomb friction. No restriction need be imposed on velocity independent forces or forces of constraint.