High-Articulation Robotic Surgical Wrist for Deterministic Positioning
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Solution Overview
Problem
Existing robotic surgical instruments face challenges in providing increased articulation, torque transmission, and mechanical manipulation, especially in minimally invasive procedures, which affect the deterministic positioning of end effectors and are prone to non-deterministic movement under external loading.
Innovation Solution
The surgical instrument features a wrist assembly with a universal joint assembly and gears in rolling contact, coupled by links, allowing for high articulation (+/â70 degrees) while maintaining deterministic end effector positioning, and includes a cable drive system to facilitate multiple-axis articulation and mechanical functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a robotic surgical instrument uses a traditional cable-driven mechanism, then the instrument structure is simpler, but the articulation range is limited and positioning precision deteriorates under external loading
Solution Approach 1:
The wrist assembly is divided into multiple independent joints (first joint and second joint) that can articulate separately. Each joint has proximal and distal segments connected by couplers, allowing independent movement control. This segmentation enables the instrument to achieve complex articulation patterns while maintaining deterministic positioning through cable-driven actuation of each segment.
Solution Approach 2:
Universal joint assemblies are introduced as intermediary components between the cable-driven joints and the end effector. These universal joints transmit motion and force while accommodating misalignment between shafts, enabling high articulation ranges without compromising the deterministic positioning provided by the cable-driven mechanism.
2Adaptability or versatility
If the robotic instrument increases articulation capability with multiple joints, then the versatility improves, but the device complexity increases
Solution Approach 1:
The wrist assembly uses universal joint assemblies that can accommodate multiple axes of rotation and misalignment in a single component. These universal joints serve multiple functions: transmitting torque, accommodating angular misalignment, and enabling articulation in multiple directions. This multi-functionality reduces the number of separate components needed compared to using multiple specialized joints.
Solution Approach 2:
The instrument employs flexible cable-driven mechanisms that can bend and articulate through multiple joints while maintaining tension and control. The cables act as flexible transmission elements that can navigate the complex geometry of the wrist assembly, providing actuation force through articulated segments without requiring rigid mechanical linkages.
3Force
If the instrument uses gears in rolling contact for joint coupling, then the torque transmission improves, but the manufacturing precision requirements increase
Solution Approach 1:
The couplers connecting proximal and distal segments utilize spherical or curved gear interfaces that engage through rolling contact. This curved geometry allows for torque transmission while accommodating slight misalignments and reducing the sensitivity to manufacturing tolerances compared to flat gear interfaces. The rolling contact minimizes sliding friction and wear.
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 provides enhanced articulation and mechanical manipulation, resisting external loading and ensuring deterministic end effector positioning, thereby improving the precision and effectiveness of robotic surgical instruments in minimally invasive procedures.
Implementation Method 1
a universal joint assembly supported within the wrist assembly... The universal joint is rotatable to actuate a function of the end effector
Implementation Method 2
The cables are movable to manipulate the first and second joints to enable the universal joint assembly and the wrist assembly to articulate relative to the longitudinal axis
Implementation Method 3
The proximal and distal segments of the first joint may include couplers (e.g., gears) supported in rolling contact with one another. The proximal and distal segments of the second joint may include couplers (e.g., gears) supported in rolling contact with one another
Data Source
AI summary
A robotic electromechanical surgical instrument includes a housing, an elongated shaft that extends distally from the housing, a wrist assembly supported on the elongated shaft, an end effector coupled to the wrist assembly, a universal joint assembly supported within the wrist assembly, and cables coupled to the wrist assembly. The elongated shaft defines a longitudinal axis. The wrist assembly includes a first joint coupled to a second joint. The universal joint assembly is rotatable to actuate a function of the end effector. The plurality of cables is movable to manipulate the first and second joints to enable the universal joint assembly and the wrist assembly to articulate relative to the longitudinal axis.