Sterile Adapter Drive Interface With Zero-Backlash Torque Coupling
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Solution Overview
Problem
Surgical instruments with robotically controlled systems face issues of backlash, leading to unpredictable motion during instrument installation, which can affect the precision and reliability of torque transmission and position control, especially in minimally invasive medical procedures.
Innovation Solution
A surgical system with a low backlash mechanical interface and drive assembly that includes a drive output disk with alignment elements, preload springs, and a cam follower assembly to ensure precise alignment and zero backlash for torque levels used in surgical procedures, minimizing instrument tip motion during installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical interface with gears or disks is used to transmit torque to surgical instruments, then the system can provide controlled motion, but backlash causes unpredictable instrument tip motion during installation
Solution Approach 1:
The patent applies preliminary action by pre-loading the mechanical interface with springs before instrument installation. The preload force ensures that the drive dogs are already engaged with the driven dogs in a predetermined orientation, eliminating backlash before the instrument begins to move. This preliminary engagement prevents unpredictable motion during the critical installation phase.
Solution Approach 2:
The patent changes the physical state of the mechanical interface by introducing elastic deformation through spring preloading. The springs apply a continuous force that maintains contact between mating surfaces, dynamically adjusting the interface parameters to eliminate clearance and prevent backlash-induced motion errors.
2Ease of operation
If drive motors are rotated back and forth during installation to ensure engagement, then secure meshing of features is achieved, but instrument tip motion becomes unpredictable
Solution Approach 1:
The patent reverses the conventional approach by applying preliminary action in the opposite direction. Instead of rotating motors to achieve engagement, the preload springs are configured to automatically engage the drive dogs with driven dogs in the correct orientation before any motor rotation occurs. This eliminates the need for post-engagement motor rotations that cause unpredictable tip motion.
3Adaptability or versatility
If clear space is provided around the instrument to accommodate random movements, then unpredictable motion during installation is tolerated, but surgical precision is compromised
Solution Approach 1:
The patent converts the potential harm of backlash into a benefit by using the elastic properties of springs to create a controlled preload force. The same elastic deformation that could cause movement is instead used to maintain continuous contact and eliminate clearance, transforming the harmful backlash effect into a beneficial preload that ensures precise positioning without requiring excessive clearance.
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 and reliable transmission of controlled torque and position, enhancing the precision and reliability of surgical instrument operation.
Implementation Method 1
a first preload spring coupled to the drive output disk. The first preload spring is compressed when the drive output disk is coupled to the intermediate disk. When the preload force is applied to the drive output disk, the coupling between the intermediate disk and the drive output disk has zero backlash for torque levels used to bring the two disks into alignment.
Data Source
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.