Towards FBG-Based Shape Sensing and Sensor Drift for a Steerable Needle

Continuum manipulators contribute to promising improvements of minimally invasive surgical procedures due to their compliance, small size, and ability to navigate anatomical pathways. Feedback of the shape of such robots within the body is currently being researched through the use of fiber Bragg grating (FBG) sensors. As the size of the robot is reduced, placement of the sensors becomes increasingly challenging, often relying on glues and epoxies. In this article, a triplet of FBG fibers is used for shape sensing of a tendon driven continuum joint. Tests are performed to show the accuracy of reconstruction using this sensor both alone and incorporated in a tendon-driven continuum joint. A repeatable sensor drift was observed during prolonged deflection which caused an increase in error of up to 0.218 mm over a 10-min period. Results showed the effect of the repeated and sustained deflection on shape reconstruction under various deflection conditions and temperatures.