Preloaded Surgical Instrument Interface for Zero-Backlash Coupling
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Solution Overview
Problem
Surgical instruments with robotically controlled systems face challenges due to backlash, which affects the transmission of controlled torque and position, leading to unpredictable instrument motion during installation and potentially compromising precision in minimally invasive procedures.
Innovation Solution
A surgical instrument manipulator assembly with a low backlash coupler and drive output disk, featuring a central body with beams and preload springs, ensures zero backlash for torque levels used in surgical procedures by aligning and securely engaging the drive output disk with the surgical instrument, minimizing instrument tip motion during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional mechanical coupling is used between drive system and surgical instrument, then the structure is simple and easy to manufacture, but backlash occurs which compromises precision and causes unpredictable instrument motion
Solution Approach 1:
A sterile adapter assembly acts as an intermediary component between the drive output unit and the surgical instrument. This adapter includes a sterile barrier that maintains the sterile field while transmitting mechanical torque, and a mechanical interface with features like drive dogs and receptacles that eliminate backlash. The intermediary structure allows precise torque transmission without compromising sterility or requiring complex sterilization of the entire drive system.
Solution Approach 2:
The patent replaces traditional friction-based or clearance-based mechanical couplings with a positive engagement mechanism featuring drive dogs and receptacles. This substitution eliminates backlash by creating direct mechanical interlocking between components, ensuring precise torque transmission from the drive system to the surgical instrument without the precision losses associated with traditional mechanical couplings.
2Reliability
If drive motors are rotated back and forth during installation to ensure engagement, then secure engagement is achieved, but unpredictable instrument motion occurs which is unacceptable for certain applications
Solution Approach 1:
The mechanical interface features are designed to automatically engage in a predetermined sequence during instrument installation. The sterile adapter assembly includes alignment features and engagement geometries that guide the drive output disk and instrument shaft into proper alignment, ensuring that drive dogs engage with their corresponding receptacles without requiring random rotation or adjustment. This preliminary design of the engagement path eliminates unpredictable motion while ensuring reliable connection.
3Reliability
If sterile barrier is interposed between docking port and instrument backend, then sterility is maintained, but torque transmission efficiency is reduced
Solution Approach 1:
The sterile adapter assembly serves as a mechanical intermediary that transmits torque through the sterile barrier. The adapter includes a sterile barrier portion that maintains the sterile field and a mechanical interface portion with drive dogs and receptacles that efficiently transmit torque. This intermediary structure allows the sterile barrier to be present without significantly compromising torque transmission, as the mechanical features are designed to engage directly and transmit forces effectively.
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 solution effectively reduces backlash to less than 0.7 degrees, ensuring precise control and stable operation of surgical instruments by maintaining zero backlash for torque levels used in surgical procedures, enhancing the reliability and accuracy of minimally invasive surgical systems.
Implementation Method 1
a first preload spring configured to apply a first preload force on the drive output disk when the first preload spring is compressed; and a second preload spring configured to apply a second preload force on the drive output disk when the second preload spring is compressed
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A surgical system (200) includes a surgical instrument (260) that is sensitive to backlash that would adversely affect the transmission of controlled torque and position to the surgical instrument. The surgical instrument (260) is coupled to motors in a surgical instrument manipulator assembly (240) via a mechanical interface. The combination of the mechanical interface and surgical instrument manipulator assembly (240) have low backlash, e.g., less than 0.7 degrees. The backlash is controlled in the surgical instrument manipulator assembly (240). From the drive output disk (545) in the surgical instrument manipulator assembly to the driven disk (964) of the surgical instrument, the mechanical interface has zero backlash for torque levels used in surgical procedures.