Novel approach for modeling separation forces between deformable bodies.

Many minimally invasive surgeries (MISs) involve removing whole organs or tumors that are connected to other organs. Development of haptic simulators that reproduce separation forces between organs can help surgeons learn MIS procedures. Powerful computational approaches such as finite-element methods generally cannot simulate separation in real time. This paper presents a novel approach for real-time computation of separation forces between deformable bodies. Separation occurs either due to fracture when a tool applies extensive forces to the bodies or due to evaporation when a laser beam burns the connection between the bodies. The separation forces are generated online from precalculated force-displacement functions that depend on the local adhesion/separation states between bodies. The precalculated functions are accurately synthesized from a large number of force responses obtained through either offline simulation, measurement, or analytical approximation during the preprocessing step. The approach does not require online computation of force versus global deformation to obtain separation forces. Only online interpolation of precalculated responses is required. The state of adhesion/separation during fracture and evaporation are updated by computationally simple models, which are derived based on the law of conservation of energy. An implementation of the approach for the haptic simulation of the removal of a diseased organ is presented, showing the fidelity of the simulation.