Port-Hamiltonian formulation and analysis of the LuGre friction model

A port-Hamiltonian formulation of the LuGre friction model is presented that can be used as a building block in the physical modeling of systems with friction. Based on the dissipation structure matrix of this port-Hamiltonian LuGre model, an alternative proof can be given for the passivity conditions that are known in the literature. As a specific example, the interconnection of a mass with the port-Hamiltonian LuGre model is presented. It is shown that the lossless interconnection structure and dissipation structure of the port-Hamiltonian LuGre model are consistent with those of the interconnection. Additionally, to render the friction model continuously differentiable, a smooth re-parametrization of the friction curve is proposed that extends and simplifies the existing results.