Low Backlash Coupler for Robotic Surgical Instrument
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Solution Overview
Problem
Surgical instruments with robotically controlled systems face challenges in minimizing backlash, which affects the transmission of controlled torque and position, especially during the installation process due to unpredictable motion caused by misalignment of drive motors and instruments.
Innovation Solution
A surgical system with a low backlash mechanical interface that includes a drive unit and a drive output assembly featuring a low backlash coupler, preload springs, and alignment elements to ensure precise alignment and zero backlash for torque levels used in surgical procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical interface is used to couple drive motors to surgical instruments, then torque and position can be transmitted, but backlash occurs that adversely affects transmission precision
Solution Approach 1:
The mechanical interface dynamically transitions from an unengaged state during installation to an engaged state during operation. The drive output disk features a beveled edge that automatically engages with the driven disk upon insertion, eliminating backlash dynamically when torque is applied during surgical procedures
Solution Approach 2:
The drive output disk is pre-configured with a beveled edge that prepares the mechanical interface for engagement. This preliminary geometric configuration ensures that when the driven disk is inserted, the beveled edge automatically guides and engages the mating features, establishing zero-backlash contact before torque transmission begins
2Reliability
If drive motors are rotated back and forth during installation to ensure engagement, then complementary features can mesh securely, but unpredictable instrument motion occurs
Solution Approach 1:
The mechanical interface is pre-configured with complementary features (drive dogs, drive dog receptacles, beveled edges) that are geometrically designed to self-align and engage automatically. This preliminary configuration eliminates the need for rotational adjustment during installation, preventing unpredictable instrument motion
Solution Approach 2:
The beveled edge on the drive output disk acts as an intermediary element that mediates the engagement process. It guides the driven disk into proper alignment and establishes mechanical contact without requiring rotational movement, thereby preventing unpredictable motion during installation
3Measurement precision
If alignment elements are added to ensure precise orientation of drive output disk, then mating accuracy improves, but device complexity increases
Solution Approach 1:
The beveled edge on the drive output disk serves multiple functions simultaneously: it acts as an alignment guide, a mechanical engagement feature, and a torque transmission element. This multi-functionality achieves precise orientation without adding separate alignment elements, thereby avoiding increased device complexity
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 system achieves minimal backlash, ensuring precise and predictable motion of surgical instruments, reducing the risk of unpredictable movements during installation and enhancing the accuracy and reliability of surgical procedures.
Implementation Method 1
a preload spring that applies a preload force to the drive output disk
Data Source
AI summary
A surgical system includes a surgical instrument that is sensitive to backlash that would adversely affect the transmission of controlled torque and position to the surgical instrument. The surgical instrument is coupled to motors in a surgical instrument manipulator assembly via a mechanical interface. The combination of the mechanical interface and surgical instrument manipulator assembly have low backlash, e.g., less than 0.7 degrees. The backlash is controlled in the surgical instrument manipulator assembly. From the drive output disk in the surgical instrument manipulator assembly to the driven disk of the surgical instrument, the mechanical interface has zero backlash for torque levels used in surgical procedures.