Flexible tip-steerable needle control with tissue uncertainty

Accurate needle insertion into soft, inhomogeneous tissue is a critical aspect of many medical problems, such as the percutaneous diagnosis and therapies. In such procedures, the flexible tip-steerable needle with bevel tips can deflect during insertion and reach the target we set beforehand. In 2D motion planning, it´s crucial to maintain the needle in a desired plane. However, the inhomogeneous and a sudden change of tissue during insertion, as well as the unmeasurable state variables, gives us a big problem to keep the needle tip in the desire plane accurately. In this paper, in order to reduce deflection of the needle from its path and to increase the accuracy of the needle tip placement, we use a feedback linearization scheme to realize the plane control based on a robust state observer, which can estimate the states of needle tip with tissue uncertainty. Simulation results are presented to illustrate the practicability of the scheme.