Fiber optic shape sensor
First Claim
1. A shape sensing method comprising:
- defining a lengthwise first segment in an optical fiber;
defining a first three-dimensional reference frame at a start location of the first segment, wherein the first reference frame is a Cartesian frame, and wherein the first reference frame comprises a first axis that is normal to the fiber and a second axis that is tangent to the fiber;
defining a Cartesian base frame at an origin location in the fiber, wherein the base frame comprises a first axis that is normal to the fiber and a second axis that is tangent to the fiber, and wherein the first axis of the first reference frame and the first axis of the base frame intersect a common core in the fiber;
interrogating the optical fiber for data associated with strain in the fiber;
outputting first bend information associated with the first segment, wherein the first bend information comprises a Cartesian position at an end location of the first segment with respect to the first reference frame; and
determining a shape of the fiber with respect to the base frame by using the first bend information, wherein determining the shape of the fiber further comprises using kinematic chain characteristics for a portion of the fiber in which no shape sensing segment is defined.
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Abstract
A shape sensing system to determine the position and orientation of one link with respect to another link in a kinematic chain. An optical fiber is coupled to two or more links in a kinematic chain. A shape sensing segment is defined to start at a proximal link and to end at a distal link, crossing one or more joints. A reference frame is defined at the start of the shape sensing segment. As the joints move, an interrogator senses strain in the shape sensing segment. The sensed strain is used to output a Cartesian position and orientation of the end of the shape sensing segment with respect to the reference frame defined at the start of the shape sensing segment. The pose of the kinematic chain is determined from the Cartesian positions and orientations of one or more shape sensing segments defined for the kinematic chain and from an a priori model and constraints of the kinematic chain.
180 Citations
16 Claims
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1. A shape sensing method comprising:
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defining a lengthwise first segment in an optical fiber; defining a first three-dimensional reference frame at a start location of the first segment, wherein the first reference frame is a Cartesian frame, and wherein the first reference frame comprises a first axis that is normal to the fiber and a second axis that is tangent to the fiber; defining a Cartesian base frame at an origin location in the fiber, wherein the base frame comprises a first axis that is normal to the fiber and a second axis that is tangent to the fiber, and wherein the first axis of the first reference frame and the first axis of the base frame intersect a common core in the fiber; interrogating the optical fiber for data associated with strain in the fiber; outputting first bend information associated with the first segment, wherein the first bend information comprises a Cartesian position at an end location of the first segment with respect to the first reference frame; and determining a shape of the fiber with respect to the base frame by using the first bend information, wherein determining the shape of the fiber further comprises using kinematic chain characteristics for a portion of the fiber in which no shape sensing segment is defined.
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2. A shape sensing method comprising:
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defining a lengthwise first segment in an optical fiber, wherein the first segment is associated with a movable mechanical constraint between two links of a kinematic chain; defining a first three-dimensional reference frame at a start location of the first segment; interrogating the optical fiber for data associated with strain in the fiber; and
,outputting first bend information associated with the first segment, wherein the first bend information comprises a Cartesian position at an end location of the first segment with respect to the first reference frame. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. A method comprising:
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interrogating a segment of an optical fiber associated with a kinematic chain to acquire information associated with bending strain in the segment; acquiring information associated with a kinematic model of the kinematic chain from an electronic memory; and outputting information associated with the kinematic configuration of the kinematic chain, wherein the information associated with the kinematic configuration is based on the acquired bending strain information and the acquired kinematic model information. - View Dependent Claims (10)
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11. An apparatus comprising:
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a kinematic chain comprising a proximal link, a distal link, and a joint coupled between the proximal and distal links; a shape sensing optical fiber associated with the kinematic chain, wherein a shape sensing segment in the optical fiber is defined in the fiber between the proximal link and the distal link, and wherein a three-dimensional reference frame is defined at a start location of the shape sensing segment; an interrogator that outputs strain information associated with shape sensing segment; and an electronic data processor that receives the strain information and outputs a Cartesian position of an end point of shape sensing segment with respect to the reference frame. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification