EndoForce: An Axial Force Sensing Device Inspired by Clinical Insertion Motion for Endoscopic Robotic Systems

Robotic endoscopic systems offer intuitive remote manipulation and reduce radiation exposure; however, the lack of axial force sensing remains an important limitation for monitoring interactions during insertion. To address this issue, we developed EndoForce, an external axial force sensing device for endoscopic robotic systems. The system integrates a load-cell-based sensing mechanism with a mechanical force transmission structure, a detachable gripper, an overload limiter, and a linear transport unit. A quasi-static model was established to describe the relationship between the externally applied axial force and the load-cell response. Benchtop experiments were conducted using a commercial ureteroscope along straight and curved insertion pathways under two insertion-speed conditions. The experimental results showed RMSE values below 0.5 N between the force measured by EndoForce and the reference force obtained from the testbed. These results demonstrate the feasibility of the proposed system for external axial force measurement during ureteroscope insertion under the tested benchtop conditions.