Towards FBG-based End-Effector Force Estimation for a Steerable Continuum Robot

Minimally invasive procedures can benefit greatly from the development of flexible and steerable devices such as robotic guidewires and catheters as well as robotic endoscopic tools. Such devices could provide clinicians with increased dexterity and offer measurements of contact forces through their ability to perform intrinsic force sensing. In this paper, we evaluate the force sensing capabilities at the tip of a 2 degree-of-freedom, meso-scale continuum robot with an outer diameter of 1.93 mm. An external tendon setup is designed and used to estimate the robot joint stiffness. Fiber Bragg grating sensors embedded within the notched nickel titanium tubes are then used to provide joint deflection feedback. This, in tandem with a derived planar kinematic model, is used to investigate the robot's external force estimation capabilities with average errors of 7.8 mN and 30 mN in the x and y components of estimated forces respectively. We further envision the proposed approach to be applicable in designing similar force sensing capabilities in micro-scale robotic guidewires.