Improved steerable needle: Design, control, and validation

Actively steerable needles have received increasing attention owing to their ability to reduce puncture deviations and enhance precision in minimally invasive procedures. However, the existing needle designs are confronted by challenges in achieving flexible deformation and controlled shape retention in complex anatomical environments. In this study, an improved actively steerable needle robot featuring a multilayer nested flexible structure is proposed. The system integrates a tendon-driven mechanism to realize segmented curvature control, thus enabling the needle to deform actively and maintain its shape during puncture. A basic kinematic model is established to describe the needle motion, and a model-free shape controller is developed to achieve precise regulation of the needle’s trajectory. The needle comprises multiple concentrically arranged flexible layers, which allows for controllable shape variation and a stable configuration through the differential actuation of tendon-like elements. A dedicated experimental platform is constructed to evaluate the performance of the proposed system. Shape-monitoring experiments without tissue constraints confirm the capability of the system to achieve accurate and stable shape control. The experimental results indicate that the needle robot can traverse complex curves with high precision, thereby validating the feasibility of the design and control approach. A novel steerable needle design that combines a multilayer structure and model-free control to achieve precise shape regulation is introduced in this study. It offers better performance than existing steerable needle systems by enhancing deformation flexibility, controllability, and adaptability, as well as provides a foundation for the further development of intelligent puncture tools in image-guided minimally invasive surgery.