Linear-Drive Virtual Fulcrum for Compact Surgical Robots
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Solution Overview
Problem
Existing medical kinematic systems face challenges in achieving a compact design while maintaining a secure and precise virtual fulcrum for guiding surgical instruments, particularly in limited operational spaces, often requiring multiple linkage mechanisms and guide cams.
Innovation Solution
A medical kinematic system with a first and second linear drive, where one drive has a fixed point and guide track with a guide cam, and the other has a variable transmission ratio, allowing the instantaneous fulcrum to move in a circular path about a virtual fulcrum, eliminating the need for additional guide cams and ensuring precise, secure positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple linkage mechanisms and guide cams are used to generate a virtual fulcrum, then the virtual fulcrum can be secured and the instrument can be guided, but the device complexity increases and the space requirement increases
Solution Approach 1:
The patent combines multiple functions into a single integrated mechanism. The parallelogram linkage structure integrates the movement guidance and virtual fulcrum generation functions that were previously separated into multiple linkage mechanisms and guide cams. This merging reduces device complexity while maintaining the virtual fulcrum stability through the geometric constraints of the parallelogram configuration.
Solution Approach 2:
The instrument holder is designed to perform multiple functions simultaneously: it holds the surgical instrument, guides its movement, and generates the virtual fulcrum effect. The parallelogram linkage mechanism serves both to maintain the instrument holder's orientation and to define the virtual fulcrum position, making the system more universal and less complex.
2Reliability
If multiple linkage mechanisms and guide cams are used to generate a virtual fulcrum, then the virtual fulcrum can be secured, but the device occupies more space which is problematic in confined operational spaces
Solution Approach 1:
By merging the virtual fulcrum generation function into the instrument holder assembly itself through the parallelogram linkage, the patent eliminates the need for separate, space-consuming linkage mechanisms and guide cams. The compact integration reduces the volume occupied by the kinematic system while maintaining virtual fulcrum stability through the inherent geometric properties of the parallelogram configuration.
3Volume of moving object
If a compact design is pursued with fewer components, then the space requirement is reduced, but achieving precise virtual fulcrum positioning becomes more difficult
Solution Approach 1:
The patent employs curved guide surfaces and cam profiles with specific geometric characteristics that inherently define the virtual fulcrum position. The curved geometry of the guide surfaces in the parallelogram linkage creates precise rotational centers through geometric constraints, ensuring accurate virtual fulcrum positioning without requiring additional precision mechanisms or components.
Data Source
AI summary
The invention relates to a medical kinematic system having a virtual fulcrum (RCM) for a medical robot for guiding a surgical instrument arranged on an instrument holder within a working zone, having a main body, a first linear drive, and a second linear drive for movably arranging an instantaneous fulcrum of the instrument holder within the working zone and simultaneously pivoting the instrument holder about the instantaneous fulcrum. The invention also relates to a medical robot having such a kinematic system and to a method for operating a medical kinematic system or a medical robot.