Model of reflective force of needle insertion for training simulation of needle intervention

Abstract

Patients have less physical damage and pain after the percutaneous procedure than other general procedure which cut the skin of patients to check and remove a lesion. However, this minimally invasive surgical procedure is more difficult for operators because visual information is less. Skilled operators perform this procedure accurately by using the haptic feedback delivered to their hand in spite of the little visual condition. Hence, training simulation that user can perform the needle intervention in a virtual environment and feel the haptic sensation at the same time is needed. Realistic haptic rendering is important to enhance the effect of the training simulation so that reflective force model defining the relationship between position, velocity of the needle and reflective force is necessary. Previous force models cannot describe the reflective force of needle insertion into multi-layer tissue about the motion used at the real needle insertion procedure properly. Although the 3-DOF motions containing 1-DOF insertion motion and 2-DOF bending motion are used at the real needle insertion procedure, all of force models of previous researches are only about 1-DOF axial force. Hence, 3-DOF reflective force models for multi-layer tissue were proposed by basing on the result of measurement using real soft tissue. A system that can measure 2-DOF reflective forces containing axial and bending moments was constructed. A Needle with 6-axis force/torque sensor was attached to a 6-DOF articulated robot, and the needle was inserted by the robot controlled as 3-link planar motion. The axial force was modeled as sum of three component forces (friction force, layer force, and cutting force), and the bending moment was modeled as a function of bending angle and insertion depth by basing on the measurement result. The friction force was modeled by modifying the Dahl friction model to contain an additional viscous friction term and be applied different parameters according ...