Physical properties of the liver for needle insertion control

Medical procedures such as RFA and cryosurgery require inserting a needle into the target location inside the body. Needle insertion is difficult because it is easy for organs to be deformed and displaced. Modeling the target object is essential in analyzing and developing a control system. Thus, a precise model is required to develop an intelligent robot that is able to insert the needle into the target area. This research uses a robot model and a liver for the target object. Four experiments were conducted to show the physical properties of the liver for robot control. A dynamic viscoelastic test was carried out to show the dynamic properties of the liver as a differential equation. The nonlinearity of the liver was supported by the creep test. In addition, the liver model was validated using a constant strain rate test. A needle insertion test was also carried out to validate the model.