Surgical Stapler Shaft Bias Control for Articulation Backlash
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Solution Overview
Problem
Mechanical backlash within the shaft of surgical staplers leads to unpredictable and unwanted movement of the articulation joint during tissue clamping and firing, compromising precision in robotic surgical systems.
Innovation Solution
Incorporation of hard-stop mechanisms at specific points along the shaft to control and mitigate mechanical backlash, ensuring precise positioning of the articulation joint by limiting proximal retraction of the knife and firing rod through contact with dedicated walls and slots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the shaft components are allowed to move freely during articulation, then the ease of operation is improved, but mechanical backlash causes unpredictable movement and reduces precision
Solution Approach 1:
The hard-stop mechanisms are pre-positioned at specific locations along the shaft to limit proximal retraction of the knife and firing rod. This preliminary positioning of mechanical constraints ensures that when articulation forces are applied, the components cannot move beyond predetermined boundaries, thereby eliminating backlash-induced positioning errors while maintaining full articulation range of motion.
Solution Approach 2:
The hard-stop mechanisms act as intermediary elements between the movable shaft components (knife, firing rod) and the shaft itself. These intermediaries provide controlled mechanical contact points that prevent excessive proximal movement while allowing distal movement, thereby mediating the conflict between operational freedom and positioning precision during articulation.
2Manufacturing precision
If hard-stop mechanisms are added to control backlash, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The shaft is segmented into distinct functional zones with hard-stop mechanisms positioned at specific locations. Rather than implementing a continuous complex constraint system, the shaft is divided into segments where controlled movement is permitted in some regions while proximal retraction is prevented in others, simplifying the overall design while achieving precision control.
Solution Approach 2:
The hard-stop mechanisms provide localized constraints at specific positions along the shaft rather than applying uniform constraints throughout. This local quality approach allows the shaft to maintain flexibility and articulation capability in regions where movement is desired, while providing precise positioning control only at critical locations where backlash elimination is most important.
Data Source
AI summary
A surgical instrument includes a base and a shaft extending distally from the base along a longitudinal axis. The shaft is configured to rotate relative to the base about the longitudinal axis. The surgical instrument also includes an end effector operatively coupled with the shaft. The end effector is configured to articulate relative to the shaft about an articulation joint. The end effector includes a first jaw and a second jaw configured to cooperate with the first jaw to clamp tissue. The second jaw is configured to support a stapling assembly. The surgical instrument further includes a firing assembly configured to be distally advanced through the shaft for driving distal translation of a staple actuator of the stapling assembly. The firing assembly is configured to be proximally retracted against at least one of the second jaw or the shaft to thereby apply a compression bias to the shaft.