Flexible Snake-Arm Robot Stiffness Control
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Solution Overview
Problem
Existing snake-arm robots lack sufficient load-carrying capacity to perform inspection and repair operations within gas turbine engines due to their small size, which restricts their ability to access and manipulate components effectively, especially in confined spaces.
Innovation Solution
A flexible snake-arm robot with a tubular backbone made of high-temperature-resistant silicone rubber, featuring radially extending projections and a cavity-filling medium that can change stiffness by heating and cooling, allowing for precise control of bending and rigidity, enabling the tool to fit through small access ports while supporting heavier loads and tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the snake-arm robot is made smaller to fit through borescope ports, then it can access confined spaces, but its load-carrying capacity decreases to a few grams
Solution Approach 1:
The patent applies dynamics by making the robot's backbone stiffness controllable through heating and cooling. The backbone material transitions between flexible and rigid states, allowing the robot to be inserted in a flexible state and then become rigid to support heavier loads for maintenance operations.
Solution Approach 2:
The patent changes the physical parameter of the backbone material's temperature to alter its mechanical properties. By heating the backbone above its glass transition temperature, it becomes flexible for insertion; by cooling it below this temperature, it becomes rigid to support loads exceeding 100 grams.
2Length of moving object
If the snake-arm robot is made longer to reach further components, then it can access distant areas, but its load-carrying capacity at the tip decreases
Solution Approach 1:
The patent uses dynamic stiffness control to overcome the length-load limitation. By making the entire backbone rigid through cooling after insertion, the robot maintains high load-carrying capacity throughout its length, enabling it to support heavy tools even at extended distances from the access port.
3Device complexity
If conventional robotic arms are used with discrete elbows, then they have simpler structure, but their flexibility is limited in confined spaces
Solution Approach 1:
The patent segments the backbone into many small elements along its length, each capable of independent bending control. This segmentation provides continuous flexibility without discrete joints, allowing the robot to navigate complex confined spaces while maintaining structural integrity and load-carrying capacity.
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 flexible tool can be steered through complex spaces to reach inaccessible areas, providing a significantly higher load-carrying capacity, enabling a wider range of operations, including grinding and deburring, without the need to remove the engine, thus enhancing the scope of in-situ maintenance and repair.
Implementation Method 1
a cavity-filling medium which is rigid at a normal operating temperature of the tool. In use, the spaces between the projections and ribs are filled with a cavity-filling medium 28. The skin 30 incorporates embedded heating elements 32. The heating elements 32 are controlled to heat the medium 28 above its glass transition temperature, so that it will melt or soften.
Implementation Method 2
the medium 28 is a thermoplastic which is rigid at the normal operating temperature of the tool... heat the medium 28 above its glass transition temperature, so that it will melt or soften
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A flexible tool (10) comprises stiffening means (28) switchable in use from a first state of relatively low stiffness to a second state of relatively high stiffness, and subsequently switchable from the second state back to the first state.