  This paper presents a novel approach to numerically describe the interactions
between rigid bodies, with a special focus on robotic grasping. Some of the
more common approaches used to address such issues rely on satisfaction of a
set of strict constraints, descriptive of the expected physical reality of such
interactions in practice. However, application of constraint-based methods in a
numerical setting may lead to problematic configurations in which, for
instance, volumes occupied by distinct bodies may overlap. Such situations
lying beyond the range of admissible configurations for constraint-based
methods, their occurrence typically results in non-meaningful simulation
outcomes. We propose a method which acknowledges the possibility of such
occurrences while demoting their occurrence. This is pursued through the use of
a penalty-based approach, and draws on notions of mechanical impedance to infer
apposite reaction forces. Results of numerical simulations illustrate efficacy
of the proposed approach.
