Systems and methods for reducing measurement error in optical fiber shape sensors

Abstract

A shape sensing apparatus comprises an instrument including an elongated shaft with a neutral axis. The shape sensor also includes a first shape sensor with an elongated optical fiber extending within the elongated shaft at a first radial distance from the neutral axis. The apparatus also includes a shape sensor compensation device extending within the elongated shaft and including a temperature sensor. The apparatus also comprises a tracking system for receiving shape data from the first shape sensor and compensating data from the shape sensor compensation device for use in calculating a bend measurement for the instrument.

1 - 26 . (canceled) 
     
     
         27 . A shape sensing apparatus comprising:
 an instrument including an elongated shaft with a neutral axis;   a first shape sensor including an elongated optical fiber extending within the elongated shaft at a first radial distance from the neutral axis;   a shape sensor compensation device extending within the elongated shaft, the shape sensor compensation device including a temperature sensor; and   a tracking system adapted to receive shape data from the first shape sensor and compensating data from the shape sensor compensation device for calculating a bend measurement for the instrument.   
     
     
         28 . The apparatus of  claim 27 , wherein the shape sensor compensation device is located at a second radial distance from the neutral axis. 
     
     
         29 . The apparatus of  claim 27 , wherein the shape sensor compensation device is located between the neutral axis and the first radial distance. 
     
     
         30 . The apparatus of  claim 27 , wherein the temperature sensor and the first shape sensor are enclosed in insulation. 
     
     
         31 . The apparatus of  claim 27 , wherein the shape sensor compensation device includes a plurality of shape sensors that together with the first shape sensor, are arranged at angular intervals about the neutral axis at the first radial distance. 
     
     
         32 . The apparatus of  claim 27 , wherein the first shape sensor includes a plurality of optical cores, each of which includes a fiber Bragg grating. 
     
     
         33 . A method of operating a shape sensing apparatus comprising:
 providing an instrument including an elongated shaft defining a neutral axis;   receiving shape data from a first shape sensor, the first shape sensor including an elongated optical fiber extending within the elongated shaft at a first radial distance from the neutral axis;   receiving compensation data from a shape sensor compensation device extending within the elongated shaft, wherein the shape sensor compensation device includes a temperature sensor; and   generating an instrument bend measurement based upon the received shape data and the compensation data.   
     
     
         34 . The method of  claim 33 , wherein the temperature sensor includes a fiber optic temperature sensor. 
     
     
         35 . The method of  claim 33 , wherein receiving compensation data includes receiving temperature data from the temperature sensor. 
     
     
         36 . The method of  claim 35 , wherein generating the instrument bend measurement comprises adjusting the shape data based on the temperature data and a set of predetermined temperature characterization data for the first shape sensor. 
     
     
         37 . The method of  claim 33 , wherein the shape sensor compensation device is located at a second radial distance from the neutral axis. 
     
     
         38 . The method of  claim 33 , wherein the shape sensor compensation device is located between the neutral axis and the first radial distance. 
     
     
         39 . The method of  claim 33 , wherein the step of receiving compensation data includes receiving axial load data from a second shape sensor which includes a second elongated optical fiber extending within the elongated shaft at a second radial distance from the neutral axis and wherein a displacement angle between the first and second shape sensor about the neutral axis is approximately 180° and the first and second radial distances are approximately equal. 
     
     
         40 . The method of  claim 33 , wherein the shape sensor compensation device includes a plurality of shape sensors that together with the first shape sensor, form a ring about the neutral axis at the first radial distance and wherein receiving compensation data further includes receiving the compensation data from one of the plurality of shape sensors located on a common bending plane with the first shape sensor. 
     
     
         41 . A medical instrument system comprising:
 an instrument including an elongated shaft with a neutral axis;   a first shape sensor including an elongated optical fiber extending within the elongated shaft at a first radial distance from the neutral axis; and   a shape sensor compensation device extending within the elongated shaft, wherein the shape sensor compensation device includes a temperature sensor;   a tracking system adapted to receive shape data from the first shape sensor and compensating data from the shape sensor compensation device for calculating a bend measurement for the instrument; and   a display system adapted to display a virtual image of the instrument using the bend measurement.   
     
     
         42 . The medical instrument system of  claim 41 , wherein the instrument includes an end effector for manipulating tissue in response to a teleoperation command. 
     
     
         43 . The medical instrument system of  claim 41 , wherein the temperature sensor includes an optical fiber. 
     
     
         44 . The medical instrument system of  claim 41 , wherein the shape sensor compensation device is located at a second radial distance from the neutral axis. 
     
     
         45 . The medical instrument system of  claim 41 , wherein the shape sensor compensation device is located between the neutral axis and the first radial distance. 
     
     
         46 . The medical instrument system of  claim 41 , wherein the shape sensor compensation device includes a plurality of shape sensors that together with the first shape sensor, are arranged at angular intervals about the neutral axis at the first radial distance.