Instrument Shaft Relief Features for Bending Flexibility and Axial Stiffness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing instrument shafts face challenges in achieving high compliance in bending while maintaining high axial and rotational stiffness, leading to undesirable behavior such as increased axial compliance and rotational backlash.
Innovation Solution
Incorporating a relief feature along the shaft's wall that defines flexural members on opposing sides, allowing them to engage on tension and compression sides when bent within a predetermined angle range, minimizing rotational backlash and maintaining axial stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the shaft is made from flexible materials to enable bending, then flexibility is improved, but axial compliance increases beyond desirable levels
Solution Approach 1:
The shaft is segmented into discrete flexural members separated by relief features, allowing controlled bending flexibility while maintaining axial stiffness through the interlocking engagement of members
Solution Approach 2:
The shaft combines rigid shaft material with flexible relief feature geometry to create a composite structure that exhibits different mechanical properties in different directions - flexible in bending, stiff in axial loading
2Adaptability or versatility
If the shaft is made from flexible materials to enable bending, then flexibility is improved, but rotational backlash increases
Solution Approach 1:
The shaft is segmented into discrete flexural members separated by relief features, allowing controlled bending flexibility while maintaining axial stiffness through the interlocking engagement of members
Solution Approach 2:
The interlocking engagement features are designed to prevent rotational backlash by creating mechanical constraints that oppose and eliminate backplay between flexural members during rotation
3Adaptability or versatility
If relief features are added to the shaft wall to define flexural members, then bending flexibility is improved, but device complexity increases
Solution Approach 1:
The shaft is segmented into discrete flexural members separated by relief features, allowing controlled bending flexibility while maintaining axial stiffness through the interlocking engagement of members
Solution Approach 2:
The relief features create thin-walled flexural members that are flexible in bending but maintain structural integrity through their geometry and interlocking engagement
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 solution provides a shaft with enhanced flexibility for close positioning of distal ends while maintaining high axial and rotational stiffness, reducing deflection and backlash, suitable for use in manipulator systems and other applications.
Implementation Method 1
The flexural members move relative to one another in response to bending the shaft
Data Source
AI summary
An instrument includes a tubular shaft, an end effector coupled to a distal end portion of the tubular shaft, and a relief feature extending circumferentially along a wall of the shaft and along at least a portion of a length of the shaft. The relief feature defines flexural members on opposing sides of the relief feature. The flexural members can move relative to one another in response to bending the shaft. The flexural members can engage one another on one or both of tension and compression sides of the shaft on the condition the shaft is bent to an angle within a predetermined range of bend angles. Systems and methods relate to instruments including such shafts.