Contact modes and complementary cones

In this paper, we use a linear complementarity problem (LCP) formulation of rigid body dynamics with unilateral contacts to obtain definitions for contact modes. We show how the complementary cones of the LCP correspond to each of the intuitive contact modes: slide right, slide left, roll and separate. These complementary cones allow us to make rigorous definitions for contact modes in three-dimensional systems, where our intuitive understanding fails.