Large Deflection Shape Sensing of a Continuum Manipulator for Minimally-Invasive Surgery

Abstract

Shape sensing techniques utilizing Fiber Bragg grating (FBG) arrays can enable real-time tracking and control of dexterous continuum manipulators (DCM) used in minimally invasive surgeries. For many surgical applications, the DCM may need to operate with much larger curvatures than what current shape sensing methods can detect. This paper proposes a novel shape sensor, which can detect a radius of curvature of 15 mm for a 35 mm long DCM. For this purpose, we used FBG sensors along with nitinol wires as the supporting substrates to form a triangular cross section. For verification, we assembled the sensor inside the wall of the DCM. Experimental results indicate that the proposed sensor can detect the DCM's curvature with an average error of 3.14%.

Fig. 1

MIS treatment of osteolysis [7].

Fig. 2

Sensor configuration for larger curvature detection.

Fig. 3

Strategy to reduce the range of wavelength shift by increasing the center distance between nitinol wires (L1>L2) a) reduced wavelength shift and b) larger wavelength shift.

Fig. 4

Shape sensing for osteolysis dexterous manipulator.

Fig. 5

The (a) Parallel nitinol wires and (b) whole assembly under microscope.

Fig. 6

Calibration board for 2D Shape Sensor Array.

Fig. 7. Calibration results for an array of 3 FBG sensors

Fig. 8. Arrangement of the FBG sensors for Shape reconstruction

Fig. 9

Shape sensing with constant curvature bending.

Fig. 10

Wavelength shift for different curvatures, calibration (blue) and verification (red).