Robotic End Effector Articulation Using Antagonistic Force Control

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Robotic surgical systems face challenges in precisely controlling articulation forces in robotic surgical arms, which affects the accuracy and reliability of surgical procedures, particularly in applying counteracting forces to the end effector.

Innovation Solution

A system that includes an articulation pivot positioned off the center axis of the robotic surgical arm, with counteracting forces applied by first and second motors to the articulation arms, allowing the end effector to articulate based on the ratio of these forces, and a control circuit that instructs the motors to apply these forces via hinges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If counteracting forces are applied by first and second motors to articulation arms, then articulation control precision is improved, but system complexity increases due to multiple motors and force coordination requirements

Engineering Contradiction:
Improvearticulation control precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies counteracting forces through first and second motors on articulation arms to achieve precise articulation control. The counteracting forces balance each other to enable accurate positioning of the end effector while managing the complexity through coordinated force application.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

2Manufacturing precision

If articulation pivot is positioned off center axis, then articulation accuracy is improved, but mechanical stress increases on articulation components

Engineering Contradiction:
Improvearticulation accuracyVSAvoidmechanical stress
Core Design Contradiction:
Manufacturing precisionVSStress or pressure

Solution Approach 1:

The articulation pivot is deliberately positioned off the center axis of the robotic surgical arm. This asymmetric positioning enables more accurate articulation control by creating optimal leverage and force distribution, while the counteracting forces from the motors compensate for the increased mechanical stress on the articulation components.

Inventive Principle:
Principle #4Asymmetry

3Ease of operation

If multiple motors control individual components with interrelationship, then articulation control is improved, but force coordination difficulty increases

Engineering Contradiction:
Improvearticulation controlVSAvoidforce coordination difficulty
Core Design Contradiction:
Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system employs multiple motors to control individual articulation components with interrelationships. The counteracting forces applied by the motors are coordinated through control systems that monitor and adjust force distribution, enabling smooth articulation control while managing the complexity of force coordination between interconnected components.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3421002B1System for controlling articulation forces
Publication Date: 2023.01.04 ETHICON INC
  • EP3421002B1 patent drawingFigure 1
  • EP3421002B1 patent drawingFigure 2
  • EP3421002B1 patent drawingFigure 3

AI summary

In some aspects, a control algorithm is provided for manipulating a pair of articulation arms configured to control an articulation angle of an end effector of a robotic surgical instrument. Other aspects of the present disclosure focus on the robotic arm system, including the pair of articulation arms coupled to the end effector and guided by independent motors controlled by a control circuit. Each of the articulation arms are designed to exert antagonistic forces competing against each other that are apportioned according to a ratio specified in the control algorithm. The ratio of the antagonistic forces may be used to determine the articulation angle of the head or end effector of the robotic surgical arm.