Master-Slave Orientation Mapping for Swooping Misalignment

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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, especially when there are swooping orientation misalignments, which result in unexpected motion of the slave surgical instrument tip during teleoperation.

Innovation Solution

A controller system that relaxes the alignment criteria, allowing for a larger permitted orientation misalignment between the master tool grip and the slave surgical instrument tip, enabling intuitive motion following without unexpected rotations by generating a desired orientation for the slave tip based on the master tool grip's orientation and stored base orientations, using a relative rotation matrix to compensate for misalignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the system requires precise alignment between master tool grip and slave surgical instrument tip, then the motion accuracy and intuitive control are improved, but the alignment process time and system complexity increase due to repeated alignment iterations

Engineering Contradiction:

Improveorientation alignment precisionVSAvoidalignment process time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system changes the parameter of orientation alignment tolerance, allowing larger misalignments (e.g., 30-45 degrees) instead of requiring precise alignment. This is achieved by modifying the control algorithm to compensate for misalignment through coordinate transformations and orientation mapping, thereby reducing alignment iteration time while maintaining motion accuracy

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical alignment process (physically adjusting components to achieve precise orientation matching) with a computational approach using coordinate transformations and orientation mapping algorithms. This substitution eliminates the need for repeated mechanical adjustments while preserving motion accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the system allows larger orientation misalignment, then the ease of operation and entry into following mode are improved, but the motion accuracy and intuitive control deteriorate due to unexpected slave instrument tip motion

Engineering Contradiction:

Improveease of entering following modeVSAvoidmotion accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The system introduces an intermediary coordinate transformation layer that maps orientations between the master tool grip and slave surgical instrument tip. This intermediary transformation compensates for large misalignments by calculating the appropriate orientation mapping, ensuring that slave instrument motion remains intuitive and accurate even when initial alignment is poor

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback from the actual orientation relationship between master and slave tools to dynamically adjust the orientation mapping. By continuously monitoring the misalignment and compensating through coordinate transformations, the system maintains motion accuracy and intuitive control despite allowing larger initial misalignments

Inventive Principle:

Principle #23Feedback

3Measurement precision

If the system performs repeated master-slave alignment processes, then the orientation alignment precision is improved, but the productivity and surgical efficiency decrease due to delays in entering following mode

Engineering Contradiction:

Improveorientation alignment precisionVSAvoidsurgical efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system performs preliminary orientation mapping and coordinate transformation setup before entering following mode, rather than requiring repeated alignment adjustments during operation. This preliminary configuration allows the system to accept larger initial misalignments while maintaining accuracy, thereby reducing delays and improving surgical efficiency

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3307198B1Master-to-slave orientation mapping when misaligned

Publication Date: 2022.11.16 INTUITIVE SURGICAL OPERATIONS INC

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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.