Robotic Arm Velocity Control via End Effector Inertia

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Solution Overview

Problem

Current minimally invasive surgical instruments lack the flexibility and intuitive control of traditional open surgery, with endoscopic tools experiencing difficulty in approaching surgical sites and reduced tactile feedback due to their length, leading to challenges in precise movement coordination.

Innovation Solution

A robotic surgical system with a control system that monitors and adjusts the velocity of the robotic arm based on the configuration and properties of the end effector, such as articulation angle and moment of inertia, to enhance precision and safety by emulating natural motion and reducing tissue damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If traditional minimally invasive surgical instruments are used, then the surgical procedure can be performed with small incisions, but the surgeon loses flexibility of tool placement and intuitive control

Engineering Contradiction:
Improveflexibility of tool placementVSAvoidlength of endoscopic instrument
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The robotic surgical system divides the surgical instrument into multiple segments: a robotic arm for positioning, a shaft for insertion through the incision, and an end effector for surgical operations. This segmentation allows the long instrument to maintain flexibility and dexterity at the distal end while the proximal portion remains stable and controllable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The robotic arm and end effector are designed with dynamic control capabilities, allowing real-time adjustment of position, orientation, and movement velocity. The system adapts the end effector's movements based on its configuration (articulation angle, moment of inertia) to provide intuitive control that emulates natural surgical motions despite the instrument's length.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the end effector is articulated at large angles, then surgical dexterity is improved, but the velocity of the robotic arm must be reduced to prevent tissue damage

Engineering Contradiction:
Improvesurgical dexterityVSAvoidvelocity of robotic arm
Core Design Contradiction:
Ease of operationVSSpeed

Solution Approach 1:

The control system continuously monitors the end effector's articulation angle and moment of inertia, and provides real-time feedback control of the robotic arm's velocity. When the end effector is articulated at large angles, the system automatically reduces velocity to prevent tissue damage, while maintaining optimal speed when the end effector is in straight configurations for efficient positioning.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes the velocity parameter of the robotic arm based on the articulation angle and moment of inertia of the end effector. This parameter adaptation allows the system to optimize the trade-off between surgical dexterity and tissue safety, adjusting movement characteristics to match the current surgical configuration.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the robotic arm moves quickly to improve productivity, then surgical efficiency increases, but precision and safety are compromised

Engineering Contradiction:
Improvesurgical efficiencyVSAvoidmovement precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The robotic arm employs dynamic velocity control that adapts to the current surgical situation. The system allows high velocities during translational movements for efficient positioning, while automatically reducing velocity during rotational movements of the end effector to maintain precision and prevent tissue damage, thereby achieving both productivity and accuracy.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system dynamically adjusts movement parameters including velocity, acceleration, and jerk based on the robotic arm's configuration and the end effector's state. This parameter optimization enables high-speed positioning while maintaining precise control during critical surgical operations, balancing productivity with precision and safety.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3500206B1Control of the rate of actuation of tool mechanism based on inherent parameters
Publication Date: 2024.07.10 ETHICON INC
  • EP3500206B1 patent drawingFigure 1
  • EP3500206B1 patent drawingFigure 2~3
  • EP3500206B1 patent drawingFigure 4

AI summary

A robotic surgical system including a control system that controls the movement of a robotic arm coupled to a tool assembly having an end effector is described. The control system can also assist with controlling either the articulation or rotation of the end effector. Furthermore, the control system can detect and monitor one or more properties (e.g., articulation, rotation, etc.), which can be used by the control system to determine one or more appropriate movement parameters of either the robotic arm (e.g., velocity of movement) or the tool assembly coupled to the robotic arm (e.g., rotational speed of the end effector). The control system can detect any number of characteristics related to the end effector and use such information to control a variety of movement parameters associated with either the robotic arm or the tool assembly.