Entry Guide Controller Velocity Limiting for Medical Robots

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Solution Overview

Problem

Medical robotic systems face challenges in controlling the linear velocity of articulatable instruments extending out of an entry guide to ensure safe and precise movement during minimally invasive surgical procedures, particularly when using a single entry aperture.

Innovation Solution

A method and system that includes an entry guide manipulator controlled by an operator's input devices, processing image commands to limit the linear velocity of instrument tips, ensuring they do not exceed a maximum allowable velocity, by determining desired mechanical states and commanding joint actuators to maintain safe movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the entry guide manipulator is commanded to move quickly to reach the work site, then productivity is improved, but the linear velocity of instrument tips may exceed safe limits causing harm to the patient

Engineering Contradiction:

Improvespeed of reaching work siteVSAvoidexcessive instrument tip velocity

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The controller acts as an intermediary between the operator's commands and the entry guide manipulator. It receives desired position commands, calculates the resulting instrument tip velocity, and compares it against safety thresholds. If the velocity would exceed safe limits, the controller adjusts the manipulator's movement to maintain safety while still progressing toward the work site.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements feedback by continuously monitoring the relationship between entry guide position, instrument length, and resulting tip velocity. The controller uses this feedback to dynamically adjust manipulator commands, ensuring that instrument tip velocity remains within safe boundaries while maintaining productivity.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If the operator has direct control over the entry guide manipulator for precise positioning, then ease of operation is improved, but control complexity increases due to velocity limiting requirements

Engineering Contradiction:

Improveoperator control over positioningVSAvoidcontroller complexity for velocity limiting

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The controller performs self-service by automatically calculating instrument tip velocity based on manipulator position commands and instrument length. It autonomously determines whether velocity limits would be exceeded and adjusts commands accordingly, reducing the operator's burden while maintaining precise control capability.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The controller serves as an intelligent intermediary that transparently handles velocity limiting calculations. It processes operator commands, applies safety constraints, and outputs adjusted commands without requiring the operator to understand the complex velocity limiting logic, thus maintaining ease of operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8961399B2Medical robotic system having entry guide controller with instrument tip velocity limiting

Publication Date: 2015.02.24 INTUITIVE SURGICAL OPERATIONS INC

AI summary

A medical robotic system includes an entry guide with articulatable instruments extending out of its distal end, an entry guide manipulator providing controllable four degrees-of-freedom movement of the entry guide, and a controller configured to limit joint velocities in the entry guide manipulator so as to prevent movement of tips of the articulatable instruments from exceeding a maximum allowable linear velocity when the entry guide manipulator is being used to move the entry guide.