A Novel FBG Shape Sensor Based on Mechanical Model for Continuum Manipulator

Fiber Bragg Gratings (FBG) are used widely for that it is small and sensitive. It is suitable to insert a sensor based on FBGs to some narrow cavities. At the same time, a slender continuum structure requires tiny sensors inside it. A multi-node differential curvature measurement sensor of FBG fiber is designed in this paper to realize temperature compensation. Considering the friction among FBG, driving wires, and niti tube and external forces applied on the end, a mechanical model about the FBG sensor and the continuum manipulator is proposed. At last, a linear interpolation method is used in the curvature estimation. Under the condition that there is no end resistance and only the bending moment and friction along the outer surface of the continuum generated by the steel wire driven by the motor the absolute measurement error of the position of the end of the continuum is 1.9mm.