Optical Fibre Shape Sensing for Flexible Robot Arms
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Solution Overview
Problem
Flexible arm robots, such as continuum arm robots and borescopes, face challenges in accurate positional control due to their flexibility, which makes it difficult to determine the exact shape and length of the robotic arm within a workspace, limiting their usability and potential for damage.
Innovation Solution
A fibre system is introduced, comprising coated optical fibres with periodic Bragg gratings, housed within flexible tubes made of shape memory alloys or superelastic materials, and coated with low-friction materials. This system is integrated into flexible arm robots to determine their shape and position with improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible tubes are used to enable robot flexibility, then adaptability is improved, but measurement precision deteriorates
Solution Approach 1:
A coating layer is introduced as an intermediary between the flexible tube and the optical fibre. This coating minimizes the twist effect transmitted from the flexible tube to the fibre, allowing the fibre to accurately measure curvature without being distorted by the tube's twisting motion, thus resolving the contradiction between flexibility and measurement precision
Solution Approach 2:
The harmful twist effect is extracted and isolated from the measurement system. The coating layer separates the twist motion of the flexible tube from the optical fibre, preventing the twist from affecting the fibre's ability to accurately measure curvature and position
2Measurement precision
If complex sensing systems are added to determine robot shape, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The mechanical sensing approach is replaced with an optical sensing system using Bragg gratings in optical fibres. This substitution provides accurate shape and position measurement through optical wavelength changes rather than mechanical sensors, improving measurement precision while maintaining relatively simple system integration
Solution Approach 2:
The optical fibre with Bragg gratings serves multiple functions simultaneously: it acts as both the structural element (running through the flexible tube) and the sensing element (measuring curvature and position). This multi-functionality reduces device complexity by eliminating the need for separate sensing components
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The fibre system enhances the positional accuracy of flexible arm robots by minimizing the effect of twist on the fibre, allowing for more precise determination of the robotic arm's shape and length, thereby increasing its usability and safety within complex workspaces.
Implementation Method 1
the at least one optical fibre having at least one portion comprising a periodic Bragg grating within the fibre
Implementation Method 2
the first flexible tube further has a first coating positioned around it... The first coating may be made from at least one of: PTFE, graphene, thin carbon material, low-friction gel, low-friction fluid or a bearing system
Implementation Method 3
The first flexible tube may be made from a shape memory alloy or a superelastic material
Implementation Method 4
The first flexible tube may be made from a shape memory alloy or a superelastic material
Data Source
AI summary
A fibre system for determining the shape of a flexible object, the system having at least one coated optical fibre, the coated optical fibre having at least one optical fibre having at least one portion including a periodic distributed Bragg reflector within the fibre, the at least one optical fibre being placed in and with a first flexible tube positioned around, and wherein the first flexible tube further has a first coating positioned around it.