Master-Slave Orientation Compensation for Misaligned Surgical Tools
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Solution Overview
Problem
Current surgical systems require precise alignment between the master tool grip and the slave surgical instrument tip, leading to delays and frustration due to repeated alignment processes and unexpected motion when orientation misalignment is large, especially during teleoperation.
Innovation Solution
The system relaxes the alignment error criterion, allowing a larger acceptable orientation misalignment between the master tool grip and the slave surgical instrument tip, using a controller to generate a desired orientation for the slave tip that preserves perceived rotation, enabling intuitive motion following despite initial misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system requires precise orientation alignment between master tool grip and slave surgical instrument tip, then the motion correspondence is accurate, but the alignment process time increases and user frustration increases
Solution Approach 1:
The system changes the parameter of acceptable orientation misalignment from a strict small angle to a relaxed larger angle (up to 90 degrees). This parameter change allows the system to enter following mode without requiring precise alignment, thereby reducing alignment iteration time while maintaining intuitive motion correspondence through the perceived rotation preservation algorithm.
2Loss of time
If the system allows large orientation misalignment, then the alignment process is faster, but the slave surgical instrument tip motion becomes unexpected and non-intuitive
Solution Approach 1:
The system changes the parameter of acceptable misalignment from small to large angles while preserving motion intuitiveness through a specific mathematical transformation. The perceived rotation algorithm ensures that when the master tool is rotated, the slave instrument rotates in the same perceived direction regardless of initial misalignment, maintaining ease of operation.
Solution Approach 2:
The system introduces an intermediary computational layer (the perceived rotation preservation algorithm) that translates master tool motions to slave instrument motions. This intermediary transformation ensures that even with large initial misalignment, the motion correspondence remains intuitive by preserving the perceived rotation direction.
3Measurement precision
If the system requires repeated alignment iterations to achieve small orientation misalignment, then the alignment precision is high, but the surgical productivity decreases
Solution Approach 1:
The system changes the precision parameter from requiring small angle misalignment to accepting large angle misalignment (up to 90 degrees). This parameter change eliminates the need for repeated alignment iterations, thereby improving surgical productivity without compromising the quality of motion correspondence through the perceived rotation preservation algorithm.
4Reliability
If the system uses strict orientation alignment criteria, then the motion correspondence is accurate, but the ease of operation decreases due to alignment difficulties
Solution Approach 1:
The system changes the alignment criterion parameter from strict small angle requirement to relaxed large angle acceptance. This makes alignment easier to achieve while maintaining motion correspondence reliability through the perceived rotation preservation algorithm that ensures intuitive motion behavior regardless of initial misalignment.
Data Source
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AI summary
A controller stores the orientations of a master tool grip and a slave surgical instrument tip upon completion of a master-slave alignment process, and enters following. During following each commanded movement of the slave surgical instrument tip from the master tool grip is processed by the controller to compensate for any alignment error between the master tool grip and the slave surgical instrument tip before following was entered. The result of this processing is that the motion of the slave surgical instrument tip intuitively corresponds to the motion of the master tool grip despite the initial swooping orientation misalignment between the master tool grip and the slave surgical instrument tip.