Modeling of the interaction force between the instrument and the trocar in minimally invasive surgery

Trocars used in Minimally Invasive Surgery (MIS) are equipped with a sealing mechanism. During the motion of an instrument through a trocar, the sealing mechanism deforms itself. None of the friction models presented in the literature capture the macroscopical deformation of the seal mechanism. Therefore a specific hybrid model is developed to describe the movement of an instrument through a trocar. The only geometrical assumption of this model is the axial symmetry of the two bodies. It can thus be applied to all problems with the same symmetry. Two operating modes are distinguished, corresponding to the deformation of the sealing mechanism on the one hand, and to the sliding phase through the trocar on the other hand. The model is identified and validated using experimental data recorded on a dedicated test setup.