Robotic Surgery Tendon Conditioning for Length Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In robotic surgery systems, the elongation of actuation tendons during use leads to uncontrollability and precision issues, particularly in miniaturized instruments, due to the inherent properties of polymeric fibers, which are not adequately addressed by existing preloading methods.
Innovation Solution
A method involving a conditioning process that applies alternating low and high tensile forces to the tendons before teleoperation, stabilizing their length and preventing undesirable elongation, thereby ensuring precise control and minimizing lost motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high initial load is applied to remove residual plasticity of tendons, then manufacturing precision of tendon length is improved, but the tendon may experience permanent elongation deformation or breakage
Solution Approach 1:
The patent applies preliminary conditioning cycles with controlled tensile loads to the tendons before final assembly. This preliminary action removes residual plasticity and stabilizes tendon length through controlled elastic deformation, preventing permanent elongation during subsequent surgical use while avoiding excessive loads that could cause breakage
Solution Approach 2:
The patent implements periodic conditioning cycles with alternating tensile and relaxed states. These periodic load applications allow the tendon fibers to gradually settle into a stable configuration, eliminating residual plasticity through repeated elastic deformation cycles without causing permanent damage
2Ease of operation
If polymeric fibers are used in miniaturized surgical instruments, then ease of operation is improved, but tendon elongation under load increases leading to loss of control precision
Solution Approach 1:
The patent applies preliminary conditioning cycles with controlled tensile loads to the tendons before final assembly. This preliminary action removes residual plasticity and stabilizes tendon length through controlled elastic deformation, preventing permanent elongation during subsequent surgical use while avoiding excessive loads that could cause breakage
Solution Approach 2:
The patent changes the physical parameters of the polymeric fibers through thermal treatment and moisture conditioning. By controlling temperature and humidity during the conditioning process, the patent optimizes the elastic properties of the polymeric fibers, reducing their elongation under load while maintaining flexibility and ease of operation
3Speed
If tendons are pre-loaded before assembly, then rapid actuation response is improved, but recoverable deformation increases causing loss of motion
Solution Approach 1:
The patent applies preliminary conditioning cycles with controlled tensile loads to the tendons before final assembly. This preliminary action removes residual plasticity and stabilizes tendon length through controlled elastic deformation, preventing permanent elongation during subsequent surgical use while avoiding excessive loads that could cause breakage
Solution Approach 2:
The patent maintains continuous tensile load on the tendons through the conditioning process and into final assembly. This continuous loading prevents the tendon from returning to a relaxed state with residual deformation, ensuring that the tendon remains in a stable, pre-conditioned configuration that provides both rapid response and minimal recoverable deformation
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
This method effectively stabilizes tendon behavior, improves control accuracy, and reduces the risk of tendon breakage by gradually increasing the load to prevent plastic recovery, ensuring reliable and precise teleoperation of surgical instruments.
Implementation Method 1
all the cords are subject to elongation when subjected to loads. New cords of the braided type typically have a high elongation of plastic-elastic nature when under load
Implementation Method 2
recoverable deformation, i.e., a relatively small deformation which is gradually recovered over a certain period of time and is often a function of the nature of the intertwinement
Implementation Method 3
non-recoverable permanent elongation deformation. The permanent elongation deformation, as described above, can be achieved by a cord breaking-in procedure, performed prior to assembly on the instrument, which can comprise loading and unloading cycles and involve a plastic elongation deformation of the fibers themselves
Implementation Method 4
Viscous creep deformation under tensile load is a time-dependent effect which affects some types of intertwined cords when subject to fatigue and can be recoverable or non-recoverable typically depending on the intensity of the applied load
Data Source
AI summary
A method conditions a surgical instrument of a robotic surgery system prior to use. An articulated end-effector has degree(s) of freedom, and a tendon, operatively connects with a motorized actuator of the robotic surgery system. The tendon mounts to the surgical instrument to connect to both a respective motorized actuator, among transmission elements, and degree(s) of freedom of the end-effector. The degree(s) of freedom are activated by respective motorized actuator action by the connected tendon. The method includes locking a degree(s) of freedom of the end-effector; tensile-stressing the respective tendon, operatively connecting the locked degree of freedom, by applying force, according to a time cycle, to the tendon. The time cycle includes a low-load period, in which a low conditioning force Flow is applied, which results in a low tensile load on the tendon; and a high-load period, in which force is applied, which results in high tensile load.